Sample records for activated carbon particle

  1. Bacteria associated with granular activated carbon particles in drinking water.

    PubMed Central

    Camper, A K; LeChevallier, M W; Broadaway, S C; McFeters, G A

    1986-01-01

    A sampling protocol was developed to examine particles released from granular activated carbon filter beds. A gauze filter/Swinnex procedure was used to collect carbon fines from 201 granular activated carbon-treated drinking water samples over 12 months. Application of a homogenization procedure (developed previously) indicated that 41.4% of the water samples had heterotrophic plate count bacteria attached to carbon particles. With the enumeration procedures described, heterotrophic plate count bacteria were recovered at an average rate of 8.6 times higher than by conventional analyses. Over 17% of the samples contained carbon particles colonized with coliform bacteria as enumerated with modified most-probable-number and membrane filter techniques. In some instances coliform recoveries were 122 to 1,194 times higher than by standard procedures. Nearly 28% of the coliforms attached to these particles in drinking water exhibited the fecal biotype. Scanning electron micrographs of carbon fines from treated drinking water showed microcolonies of bacteria on particle surfaces. These data indicate that bacteria attached to carbon fines may be an important mechanism by which microorganisms penetrate treatment barriers and enter potable water supplies. PMID:3767356

  2. Particle emissions from laboratory activities involving carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Lo, Li-Ming; Tsai, Candace S.-J.; Heitbrink, William A.; Dunn, Kevin H.; Topmiller, Jennifer; Ellenbecker, Michael

    2017-08-01

    This site study was conducted in a chemical laboratory to evaluate nanomaterial emissions from 20-30-nm-diameter bundles of single-walled carbon nanotubes (CNTs) during product development activities. Direct-reading instruments were used to monitor the tasks in real time, and airborne particles were collected using various methods to characterize released nanomaterials using electron microscopy and elemental carbon (EC) analyses. CNT clusters and a few high-aspect-ratio particles were identified as being released from some activities. The EC concentration (0.87 μg/m3) at the source of probe sonication was found to be higher than other activities including weighing, mixing, centrifugation, coating, and cutting. Various sampling methods all indicated different levels of CNTs from the activities; however, the sonication process was found to release the highest amounts of CNTs. It can be cautiously concluded that the task of probe sonication possibly released nanomaterials into the laboratory and posed a risk of surface contamination. Based on these results, the sonication of CNT suspension should be covered or conducted inside a ventilated enclosure with proper filtration or a glovebox to minimize the potential of exposure.

  3. [Study on influence between activated carbon property and immobilized biological activated carbon purification effect].

    PubMed

    Wang, Guang-zhi; Li, Wei-guang; He, Wen-jie; Han, Hong-da; Ding, Chi; Ma, Xiao-na; Qu, Yan-ming

    2006-10-01

    By means of immobilizing five kinds of activated carbon, we studied the influence between the chief activated carbon property items and immobilized bioactivated carbon (IBAC) purification effect with the correlation analysis. The result shows that the activated carbon property items which the correlation coefficient is up 0.7 include molasses, abrasion number, hardness, tannin, uniform coefficient, mean particle diameter and effective particle diameter; the activated carbon property items which the correlation coefficient is up 0.5 include pH, iodine, butane and tetrachloride. In succession, the partial correlation analysis shows that activated carbon property items mostly influencing on IBAC purification effect include molasses, hardness, abrasion number, uniform coefficient, mean particle diameter and effective particle diameter. The causation of these property items bringing influence on IBAC purification is that the activated carbon holes distribution (representative activated carbon property item is molasses) provides inhabitable location and adjust food for the dominance bacteria; the mechanical resist-crash property of activated carbon (representative activated carbon property items: abrasion number and hardness) have influence on the stability of biofilm; and the particle diameter size and distribution of activated carbon (representative activated carbon property items: uniform coefficient, mean particle diameter and effective particle diameter) can directly affect the force of water in IBAC filter bed, which brings influence on the dominance bacteria immobilizing on activated carbon.

  4. Identifying, counting, and characterizing superfine activated-carbon particles remaining after coagulation, sedimentation, and sand filtration.

    PubMed

    Nakazawa, Yoshifumi; Matsui, Yoshihiko; Hanamura, Yusuke; Shinno, Koki; Shirasaki, Nobutaka; Matsushita, Taku

    2018-07-01

    Superfine powdered activated carbon (SPAC; particle diameter ∼1 μm) has greater adsorptivity for organic molecules than conventionally sized powdered activated carbon (PAC). Although SPAC is currently used in the pretreatment to membrane filtration at drinking water purification plants, it is not used in conventional water treatment consisting of coagulation-flocculation, sedimentation, and rapid sand filtration (CSF), because it is unclear whether CSF can adequately remove SPAC from the water. In this study, we therefore investigated the residual SPAC particles in water after CSF treatment. First, we developed a method to detect and quantify trace concentration of carbon particles in the sand filtrate. This method consisted of 1) sampling particles with a membrane filter and then 2) using image analysis software to manipulate a photomicrograph of the filter so that black spots with a diameter >0.2 μm (considered to be carbon particles) could be visualized. Use of this method revealed that CSF removed a very high percentage of SPAC: approximately 5-log in terms of particle number concentrations and approximately 6-log in terms of particle volume concentrations. When waters containing 7.5-mg/L SPAC and 30-mg/L PAC, concentrations that achieved the same adsorption performance, were treated, the removal rate of SPAC was somewhat superior to that of PAC, and the residual particle number concentrations for SPAC and PAC were at the same low level (100-200 particles/mL). Together, these results suggest that SPAC can be used in place of PAC in CSF treatment without compromising the quality of the filtered water in terms of particulate matter contamination. However, it should be noted that the activated carbon particles after sand filtration were smaller in terms of particle size and were charge-neutralized to a lesser extent than the activated carbon particles before sand filtration. Therefore, the tendency of small particles to escape in the filtrate would appear

  5. Influence of adhesion to activated carbon particles on the viability of waterborne pathogenic bacteria under flow.

    PubMed

    van der Mei, Henny C; Atema-Smit, Jelly; Jager, Debbie; Langworthy, Don E; Collias, Dimitris I; Mitchell, Michael D; Busscher, Henk J

    2008-07-01

    In rural areas around the world, people often rely on water filtration plants using activated carbon particles for safe water supply. Depending on the carbon surface, adhering microorganisms die or grow to form a biofilm. Assays to assess the efficacy of activated carbons in bacterial removal do not allow direct observation of bacterial adhesion and the determination of viability. Here we propose to use a parallel plate flow chamber with carbon particles attached to the bottom plate to study bacterial adhesion to individual carbon particles and determine the viability of adhering bacteria. Observation and enumeration is done after live/dead staining in a confocal laser scanning microscope. Escherichiae coli adhered in higher numbers than Raoultella terrigena, except to a coconut-based carbon, which showed low bacterial adhesion compared to other wood-based carbon types. After adhesion, 83-96% of the bacteria adhering to an acidic carbon were dead, while on a basic carbon 54-56% were dead. A positively charged, basic carbon yielded 76-78% bacteria dead, while on a negatively charged coconut-based carbon only 32-37% were killed upon adhesion. The possibility to determine both adhesion as well as the viability of adhering bacteria upon adhesion to carbon particles is most relevant, because if bacteria adhere but remain viable, this still puts the water treatment system at risk, as live bacteria can grow and form a biofilm that can then be shedded to cause contamination. (c) 2008 Wiley Periodicals, Inc.

  6. Particle Size Effects on Fenton Regeneration of MTBE-spent Activated Carbon

    EPA Science Inventory

    Fenton-driven regeneration of spent granular activated carbon (GAC) is a developing technology that may reduce water treatment costs. In this study, the effect of GAC particle size on Fenton-driven oxidation of methyl tert-butyl ether (MTBE)-spent GAC was evaluated. The GAC was...

  7. Carbon particles

    DOEpatents

    Hunt, Arlon J.

    1984-01-01

    A method and apparatus whereby small carbon particles are made by pyrolysis of a mixture of acetylene carried in argon. The mixture is injected through a nozzle into a heated tube. A small amount of air is added to the mixture. In order to prevent carbon build-up at the nozzle, the nozzle tip is externally cooled. The tube is also elongated sufficiently to assure efficient pyrolysis at the desired flow rates. A key feature of the method is that the acetylene and argon, for example, are premixed in a dilute ratio, and such mixture is injected while cool to minimize the agglomeration of the particles, which produces carbon particles with desired optical properties for use as a solar radiant heat absorber.

  8. Carbon-rich particles in Comet Halley

    NASA Technical Reports Server (NTRS)

    Clark, Benton C.

    1990-01-01

    The majority of particles detected in the coma of Comet Halley contain carbon atoms; many of these grains appear to consist preponderately or only of light elements. These light-element particles may be composed of organic compounds. Of the possible combinations of the elements hydrogen, carbon, nitrogen, and oxygen, numerous examples are found of particles containing the combinations (H,C,O,N), (H,C,N), (H,C,O), and (H,C). These results may bear on the recent detection of polyoxymethylene fragments, the observation of cyanojets (CN patterns consistent with release from solid particles), the possible presence of cyanopolyacetylenes or HCN polymer and the make-up of the CHON particles. If cometary matter could reach the surface of the earth without complete disruption, these diverse organic and mixed particles could create unique microenvironments, possibly with significant or even pivotal prebiotic chemical activity. Here a speculative insight into possible relationships between carbon in comets and carbon in life is given, as well as a brief overview of on-going analysis of data from the highly successful Particle Impact Analyzer (PIA) experiment flown on the Giotto spacecraft for the flyby of Comet Halley (development and implementation of PIA was under the direction of J. Kissel of the Max Planck Institute for Kernphysik, Heidelberg). PIA is a time-of-flight analyzer which obtains mass spectra of ions from individual particles impacting on a Pt-Ag foil target within the instrument.

  9. Carbon-particle generator

    DOEpatents

    Hunt, A.J.

    1982-09-29

    A method and apparatus whereby small carbon particles are made by pyrolysis of a mixture of acetylene carried in argon. The mixture is injected through a nozzle into a heated tube. A small amount of air is added to the mixture. In order to prevent carbon build-up at the nozzle, the nozzle tip is externally cooled. The tube is also elongated sufficiently to assure efficient pyrolysis at the desired flow rates. A key feature of the method is that the acetylene and argon, for example, are premixed in a dilute ratio, and such mixture is injected while cool to minimize the agglomeration of the particles, which produces carbon particles with desired optical properties for use as a solar radiant heat absorber.

  10. Activated carbon material

    DOEpatents

    Evans, A. Gary

    1978-01-01

    Activated carbon particles for use as iodine trapping material are impregnated with a mixture of selected iodine and potassium compounds to improve the iodine retention properties of the carbon. The I/K ratio is maintained at less than about 1 and the pH is maintained at above about 8.0. The iodine retention of activated carbon previously treated with or coimpregnated with triethylenediamine can also be improved by this technique. Suitable flame retardants can be added to raise the ignition temperature of the carbon to acceptable standards.

  11. Stable carbonous catalyst particles and method for making and utilizing same

    DOEpatents

    Ganguli, Partha S.; Comolli, Alfred G.

    2005-06-14

    Stable carbonous catalyst particles composed of an inorganic catalytic metal/metal oxide powder and a carbonaceous binder material are formed having a basic inner substantially uniform-porous carbon coating of the catalytic powder, and may include an outer porous carbon coating layer. Suitable inorganic catalytic powders include zinc-chromite (ZnO/Cr.sub.2 03) and suitable carbonaceous liquid binders having molecular weight of 200-700 include partially polymerized furfuryl alcohol, which are mixed together, shaped and carbonized and partially oxidized at elevated temperature. Such stable carbonous catalyst particles such as 0.020-0.100 inch (0.51-2.54 mm) diameter extrudates, have total carbon content of 2-25 wt. % and improved crush strength of 1.0-5 1b/mn, 50-300 m.sup.2 /g surface area, and can be advantageously utilized in fixed bed or ebullated/fluidized bed reactor operations. This invention also includes method steps for making the stable carbonous catalyst particles having improved particle strength and catalytic activity, and processes for utilizing the active stable carbonous carbon-coated catalysts such as for syn-gas reactions in ebullated/fluidized bed reactors for producing alcohol products and Fischer-Tropsch synthesis liquid products.

  12. Carbon fuel particles used in direct carbon conversion fuel cells

    DOEpatents

    Cooper, John F.; Cherepy, Nerine

    2012-10-09

    A system for preparing particulate carbon fuel and using the particulate carbon fuel in a fuel cell. Carbon particles are finely divided. The finely dividing carbon particles are introduced into the fuel cell. A gas containing oxygen is introduced into the fuel cell. The finely divided carbon particles are exposed to carbonate salts, or to molten NaOH or KOH or LiOH or mixtures of NaOH or KOH or LiOH, or to mixed hydroxides, or to alkali and alkaline earth nitrates.

  13. Carbon Fuel Particles Used in Direct Carbon Conversion Fuel Cells

    DOEpatents

    Cooper, John F.; Cherepy, Nerine

    2008-10-21

    A system for preparing particulate carbon fuel and using the particulate carbon fuel in a fuel cell. Carbon particles are finely divided. The finely dividing carbon particles are introduced into the fuel cell. A gas containing oxygen is introduced into the fuel cell. The finely divided carbon particles are exposed to carbonate salts, or to molten NaOH or KOH or LiOH or mixtures of NaOH or KOH or LiOH, or to mixed hydroxides, or to alkali and alkaline earth nitrates.

  14. Carbon fuel particles used in direct carbon conversion fuel cells

    DOEpatents

    Cooper, John F [Oakland, CA; Cherepy, Nerine [Oakland, CA

    2011-08-16

    A system for preparing particulate carbon fuel and using the particulate carbon fuel in a fuel cell. Carbon particles are finely divided. The finely dividing carbon particles are introduced into the fuel cell. A gas containing oxygen is introduced into the fuel cell. The finely divided carbon particles are exposed to carbonate salts, or to molten NaOH or KOH or LiOH or mixtures of NaOH or KOH or LiOH, or to mixed hydroxides, or to alkali and alkaline earth nitrates.

  15. Carbon fuel particles used in direct carbon conversion fuel cells

    DOEpatents

    Cooper, John F [Oakland, CA; Cherepy, Nerine [Oakland, CA

    2012-01-24

    A system for preparing particulate carbon fuel and using the particulate carbon fuel in a fuel cell. Carbon particles are finely divided. The finely dividing carbon particles are introduced into the fuel cell. A gas containing oxygen is introduced into the fuel cell. The finely divided carbon particles are exposed to carbonate salts, or to molten NaOH or KOH or LiOH or mixtures of NaOH or KOH or LiOH, or to mixed hydroxides, or to alkali and alkaline earth nitrates.

  16. Factors affecting the behavior of unburned carbon upon steam activation

    NASA Astrophysics Data System (ADS)

    Lu, Zhe

    The main objective of this study is to investigate the factors that could affect the behavior of unburned carbon samples upon steam activation. Through this work, the relationships among the factors that could influence the carbon-steam reaction with the surface area of the produced activated carbon were explored. Statistical analysis was used to relate the chemical and physical properties of the unburned carbon to the surface area of the activated carbon. Six unburned carbons were selected as feedstocks for activated carbon, and marked as UCA through UCF. The unburned carbons were activated using steam at 850°C for 90 minutes, and the surface areas of their activated counterparts were measured using N2 adsorption isotherms at 77K. The activated carbons produced from different unburned carbon precursors presented different surface areas at similar carbon burn-off levels. Moreover, in different carbon burn-off regions, the sequences for surface area of activated carbons from different unburned carbon samples were different. The factors that may affect the carbon-steam gasification reactions, including the concentration of carbon active sites, the crystallite size of the carbon, the intrinsic porous structure of carbon, and the inorganic impurities, were investigated. All unburned carbons investigated in this study were similar in that they showed the very broad (002) and (10 ) carbon peaks, which are characteristic of highly disordered carbonaceous materials. In this study, the unburned carbon samples contained about 17--48% of inorganic impurities. Compared to coals, the unburned carbon samples contain a larger amount of inorganic impurities as a result of the burn-off, or at lease part, of the carbon during the combustion process. These inorganic particles were divided into two groups in terms of the way they are associated with carbon particles: free single particles, and particles combined with carbon particles. As indicated from the present work, unburned

  17. Filling carbon nanotubes with particles.

    PubMed

    Kim, Byong M; Qian, Shizhi; Bau, Haim H

    2005-05-01

    The filling of carbon nanotubes (CNTs) with fluorescent particles was studied experimentally and theoretically. The fluorescent signals emitted by the particles were visible through the walls of the nanotubes, and the particles inside the tubes were observable with an electron microscope. Taking advantage of the template-grown carbon nanotubes' transparency to fluorescent light, we measured the filling rate of the tubes with particles at room conditions. Liquids such as ethylene glycol, water, and ethylene glycol/water mixtures, laden with 50 nm diameter fluorescent particles, were brought into contact with 500 nm diameter CNTs. The liquid and the particles' transport were observed, respectively, with optical and fluorescence microscopy. The CNTs were filled controllably with particles by the complementary action of capillary forces and the evaporation of the liquid. The experimental results were compared and favorably agreed with theoretical predictions. This is the first report on fluorescence studies of particle transport in carbon nanotubes.

  18. Comparing activated carbon of different particle sizes on enhancing methane generation in upflow anaerobic digester.

    PubMed

    Xu, Suyun; He, Chuanqiu; Luo, Liwen; Lü, Fan; He, Pinjing; Cui, Lifeng

    2015-11-01

    Two sizes of conductive particles, i.e. 10-20 mesh granulated activated carbon (GAC) and 80-100 mesh powdered activated carbon (PAC) were added into lab-scale upflow anaerobic sludge blanket reactors, respectively, to testify their enhancement on the syntrophic metabolism of alcohols and volatile fatty acids (VFAs) in 95days operation. When OLR increased to more than 5.8gCOD/L/d, the differences between GAC/PAC supplemented reactors and the control reactor became more significant. The introduction of activated carbon could facilitate the enrichment of methanogens and accelerate the startup of methanogenesis, as indicated by enhanced methane yield and substrate degradation. High-throughput pyrosequencing analysis showed that syntrophic bacteria and Methanosarcina sp. with versatile metabolic capability increased in the tightly absorbed fraction on the PAC surface, leading to the promoted syntrophic associations. Thus PAC prevails over than GAC for methanogenic reactor with heavy load. Copyright © 2015 Elsevier Ltd. All rights reserved.

  19. Characterization and observation of water-based nanofluids quench medium with carbon particle content variation

    NASA Astrophysics Data System (ADS)

    Yahya, S. S.; Harjanto, S.; Putra, W. N.; Ramahdita, G.; Kresnodrianto, Mahiswara, E. P.

    2018-05-01

    Recently, nanofluids have been widely used in heat treatment industries as quench medium with better quenching performance. The thermal conductivity of nanofluids is higher compared to conventional quench medium such as polymer, water, brine, and petroleum-based oil. This characteristic can be achieved by mixing high thermal conductivity particles in nanometer scale with a fluid as base. In this research, carbon powder and distilled water were used as nanoparticles and base respectively. The carbon source used in this research was laboratory grade carbon powder, and activated carbon as a cheaper alternative source. By adjusting the percentage of dispersed carbon particles, thermal conductivity of nanofluids could be controlled as needed. To obtain nanoscale carbon particles, planetary ball mill was used to grind laboratory-grade carbon and active carbon powder to further decrease its particle size. This milling method will provide nanoparticles with lower production cost. Milling speed and duration were set at 500 rpm and 15 hours. Scanning electron microscope (SEM) and Energy Dispersive X-Ray (EDX) were carried out respectively to determine the particle size, material identification, particle morphology. The carbon nanoparticle content in nanofluids quench mediums for this research were varied at 0.1, 0.3, and 0.5 % vol. Furthermore, these mediums were used to quench AISI 1045 carbon steel samples which had been annealed at 1000 °C. Hardness testing and metallography observation were then conducted to check the effect of different quench medium in steel samples. Preliminary characterizations showed that the carbon particle dimension after milling was hundreds of nanometers, or still in sub-micron range. Therefore, the milling process parameters are need to be optimized further. EDX observation in laboratory-grade carbon powder showed that the powder was pure carbon as expected for, but in activated carbon has some impurities. The nanofluid itself, however, was

  20. Fenton-driven regeneration of MTBE-spent granular activated carbon - Effects of particle size and Iron Amendment Procedures

    EPA Science Inventory

    Fenton-driven regeneration of spent granular activated carbon (GAC) is a technology being developed to regenerate organic contaminant-spent GAC. Here, the effect of GAC particle size (>2 mm to <0.35 mm) on Fenton-driven oxidation of methyl tert-butyl ether (MTBE)-spent GAC was ev...

  1. Ultrafine carbon particles promote rotenone-induced dopamine neuronal loss through activating microglial NADPH oxidase

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wang, Yinxi; Liu, Dan; Zhang, Huifeng

    Background: Atmospheric ultrafine particles (UFPs) and pesticide rotenone were considered as potential environmental risk factors for Parkinson's disease (PD). However, whether and how UFPs alone and in combination with rotenone affect the pathogenesis of PD remains largely unknown. Methods: Ultrafine carbon black (ufCB, a surrogate of UFPs) and rotenone were used individually or in combination to determine their roles in chronic dopaminergic (DA) loss in neuron-glia, and neuron-enriched, mix-glia cultures. Immunochemistry using antibody against tyrosine hydroxylase was performed to detect DA neuronal loss. Measurement of extracellular superoxide and intracellular reactive oxygen species (ROS) were performed to examine activation of NADPHmore » oxidase. Genetic deletion and pharmacological inhibition of NADPH oxidase and MAC-1 receptor in microglia were employed to examine their role in DA neuronal loss triggered by ufCB and rotenone. Results: In rodent midbrain neuron-glia cultures, ufCB and rotenone alone caused neuronal death in a dose-dependent manner. In particularly, ufCB at doses of 50 and 100 μg/cm{sup 2} induced significant loss of DA neurons. More importantly, nontoxic doses of ufCB (10 μg/cm{sup 2}) and rotenone (2 nM) induced synergistic toxicity to DA neurons. Microglial activation was essential in this process. Furthermore, superoxide production from microglial NADPH oxidase was critical in ufCB/rotenone-induced neurotoxicity. Studies in mix-glia cultures showed that ufCB treatment activated microglial NADPH oxidase to induce superoxide production. Firstly, ufCB enhanced the expression of NADPH oxidase subunits (gp91{sup phox}, p47{sup phox} and p40{sup phox}); secondly, ufCB was recognized by microglial surface MAC-1 receptor and consequently promoted rotenone-induced p47{sup phox} and p67{sup phox} translocation assembling active NADPH oxidase. Conclusion: ufCB and rotenone worked in synergy to activate NADPH oxidase in microglia, leading to

  2. Low-Temperature Synthesis of Hierarchical Amorphous Basic Nickel Carbonate Particles for Water Oxidation Catalysis.

    PubMed

    Yang, Yisu; Liang, Fengli; Li, Mengran; Rufford, Thomas E; Zhou, Wei; Zhu, Zhonghua

    2015-07-08

    Amorphous nickel carbonate particles are catalysts for the oxygen evolution reaction (OER), which plays a critical role in the electrochemical splitting of water. The amorphous nickel carbonate particles can be prepared at a temperature as low as 60 °C by an evaporation-induced precipitation (EIP) method. The products feature hierarchical pore structures. The mass-normalized activity of the catalysts, measured at an overpotential of 0.35 V, was 55.1 A g(-1) , with a Tafel slope of only 60 mV dec(-1) . This catalytic activity is superior to the performance of crystalline NiOx particles and β-Ni(OH)2 particles, and compares favorably to state-of-the-art RuO2 catalysts. The activity of the amorphous nickel carbonate is remarkably stable during a 10 000 s chronoamperometry test. Further optimization of synthesis parameters reveals that the amorphous structure can be tuned by adjusting the H2 O/Ni ratio in the precursor mixture. These results suggest the potential application of easily prepared hierarchical basic nickel carbonate particles as cheap and robust OER catalysts with high activity. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. ENHANCED TOXICITY OF CHARGED CARBON NANOTUBES AND ULTRAFINE CARBON BLACK PARTICLES

    EPA Science Inventory

    Man-made carbonaceous nano-particles such as single and multi-walled carbon nano-tubes (CNT) and ultra-fine carbon black (UFCB) particles are finding increasing applications in industry, but their potential toxic effects is of concern. In aqueous media, these particles cluster in...

  4. Disinfection of bacteria attached to granular activated carbon.

    PubMed Central

    LeChevallier, M W; Hassenauer, T S; Camper, A K; McFeters, G A

    1984-01-01

    Heterotrophic plate count bacteria, coliform organisms, and pathogenic microorganisms attached to granular activated carbon particles were examined for their susceptibility to chlorine disinfection. When these bacteria were grown on carbon particles and then disinfected with 2.0 mg of chlorine per liter (1.4 to 1.6 mg of free chlorine residual per liter after 1 h) for 1 h, no significant decrease in viable counts was observed. Washed cells attached to the surface of granular activated carbon particles showed similar resistance to chlorine, but a progressive increase in sublethal injury was found. Observations made by scanning electron microscope indicated that granular activated carbon was colonized by bacteria which grow in cracks and crevices and are coated by an extracellular slime layer. These data suggest a possible mechanism by which treatment and disinfection barriers can be penetrated and pathogenic bacteria may enter drinking water supplies. Images PMID:6508306

  5. An efficient visible-light photocatalyst prepared by modifying AgBr particles with a small amount of activated carbon

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wang, Desong, E-mail: dswang06@126.com; Zhao, Mangmang; Luo, Qingzhi

    2016-04-15

    Highlights: • An efficient visible-light photocatalyst was prepared by modifying AgBr particles. • A small amount of activated carbon was used to modify AgBr particles. • The modified AgBr exhibited improved visible-light photocatalytic performances. - Abstract: An efficient visible-light photocatalyst was successfully prepared by modifying AgBr particles with a small amount of activated carbon (AC) via a simple chemical precipitation approach. The AC/AgBr composite was characterized by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, UV–vis diffuse reflection spectroscopy, photoluminescence spectroscopy, electrochemical impedance spectroscopy. The photocatalytic performances of the AC/AgBr composite were investigated by evaluating photodegradation of methyl orange (MO)more » and phenol under visible light irradiation, and the effects of the AC content in the composite, concentrations of AC/AgBr composite and MO, carrier scavengers on MO photodegradation rate were systematically investigated. The results indicated that the modification of AC can hardly change the crystalline and crystal size of AgBr particles, while significantly improve their specific surface areas, visible-light absorption and separation efficiency of photogenerated electron–hole pairs. Compared with pure AgBr, the AC/AgBr composite exhibited drastically enhanced visible-light photocatalytic activity and stability. The photogenerated electrons and holes, hydroxyl radicals are responsible to the photodegradation of organic pollutants, and the photogenerated holes are the main active species. On the basis of the results and the properties of AC and AgBr, the visible-light photocatalytic mechanism of the AC/AgBr composite was discussed.« less

  6. Activated coconut shell charcoal carbon using chemical-physical activation

    NASA Astrophysics Data System (ADS)

    Budi, Esmar; Umiatin, Nasbey, Hadi; Bintoro, Ridho Akbar; Wulandari, Futri; Erlina

    2016-02-01

    The use of activated carbon from natural material such as coconut shell charcoal as metal absorbance of the wastewater is a new trend. The activation of coconut shell charcoal carbon by using chemical-physical activation has been investigated. Coconut shell was pyrolized in kiln at temperature about 75 - 150 °C for about 6 hours in producing charcoal. The charcoal as the sample was shieved into milimeter sized granule particle and chemically activated by immersing in various concentration of HCl, H3PO4, KOH and NaOH solutions. The samples then was physically activated using horizontal furnace at 400°C for 1 hours in argon gas environment with flow rate of 200 kg/m3. The surface morphology and carbon content of activated carbon were characterized by using SEM/EDS. The result shows that the pores of activated carbon are openned wider as the chemical activator concentration is increased due to an excessive chemical attack. However, the pores tend to be closed as further increasing in chemical activator concentration due to carbon collapsing.

  7. Protection of porous carbon fuel particles from boudouard corrosion

    DOEpatents

    Cooper, John F.

    2015-05-26

    A system for producing energy that includes infusing porous carbon particles produced by pyrolysis of carbon-containing materials with an off-eutectic salt composition thus producing pore-free carbon particles, and reacting the carbon particles with oxygen in a fuel cell according to the reaction C+O.sub.2=CO.sub.2 to produce electrical energy.

  8. Dose-dependent regulation of microbial activity on sinking particles by polyunsaturated aldehydes: Implications for the carbon cycle

    NASA Astrophysics Data System (ADS)

    Edwards, Bethanie R.; Bidle, Kay D.; Van Mooy, Benjamin A. S.

    2015-05-01

    Diatoms and other phytoplankton play a crucial role in the global carbon cycle, fixing CO2 into organic carbon, which may then be exported to depth via sinking particles. The molecular diversity of this organic carbon is vast and many highly bioactive molecules have been identified. Polyunsaturated aldehydes (PUAs) are bioactive on various levels of the marine food web, and yet the potential for these molecules to affect the fate of organic carbon produced by diatoms remains an open question. In this study, the effects of PUAs on the natural microbial assemblages associated with sinking particles were investigated. Sinking particles were collected from 150 m in the water column and exposed to varying concentrations of PUAs in dark incubations over 24 h. PUA doses ranging from 1 to 10 µM stimulated respiration, organic matter hydrolysis, and cell growth by bacteria associated with sinking particles. PUA dosages near 100 µM appeared to be toxic, resulting in decreased bacterial cell abundance and metabolism, as well as pronounced shifts in bacterial community composition. Sinking particles were hot spots for PUA production that contained concentrations within the stimulatory micromolar range in contrast to previously reported picomolar concentrations of these compounds in bulk seawater. This suggests PUAs produced in situ stimulate the remineralization of phytoplankton-derived sinking organic matter, decreasing carbon export efficiency, and shoaling the average depths of nutrient regeneration. Our results are consistent with a "bioactivity hypothesis" for explaining variations in carbon export efficiency in the oceans.

  9. Dose-dependent regulation of microbial activity on sinking particles by polyunsaturated aldehydes: Implications for the carbon cycle.

    PubMed

    Edwards, Bethanie R; Bidle, Kay D; Van Mooy, Benjamin A S

    2015-05-12

    Diatoms and other phytoplankton play a crucial role in the global carbon cycle, fixing CO2 into organic carbon, which may then be exported to depth via sinking particles. The molecular diversity of this organic carbon is vast and many highly bioactive molecules have been identified. Polyunsaturated aldehydes (PUAs) are bioactive on various levels of the marine food web, and yet the potential for these molecules to affect the fate of organic carbon produced by diatoms remains an open question. In this study, the effects of PUAs on the natural microbial assemblages associated with sinking particles were investigated. Sinking particles were collected from 150 m in the water column and exposed to varying concentrations of PUAs in dark incubations over 24 h. PUA doses ranging from 1 to 10 µM stimulated respiration, organic matter hydrolysis, and cell growth by bacteria associated with sinking particles. PUA dosages near 100 µM appeared to be toxic, resulting in decreased bacterial cell abundance and metabolism, as well as pronounced shifts in bacterial community composition. Sinking particles were hot spots for PUA production that contained concentrations within the stimulatory micromolar range in contrast to previously reported picomolar concentrations of these compounds in bulk seawater. This suggests PUAs produced in situ stimulate the remineralization of phytoplankton-derived sinking organic matter, decreasing carbon export efficiency, and shoaling the average depths of nutrient regeneration. Our results are consistent with a "bioactivity hypothesis" for explaining variations in carbon export efficiency in the oceans.

  10. Intra-particle migration of mercury in granular polysulfide-rubber-coated activated carbon (PSR-AC)

    PubMed Central

    Kim, Eun-Ah; Masue-Slowey, Yoko; Fendorf, Scott; Luthy, Richard G.

    2011-01-01

    The depth profile of mercuric ion after the reaction with polysulfide-rubber-coated activated carbon (PSR-AC) was investigated using micro-x-ray fluorescence (μ-XRF) imaging techniques and mathematical modeling. The μ-XRF results revealed that mercury was concentrated at 0~100 μm from the exterior of the particle after three months of treatment with PSR-AC in 10 ppm HgCl2 aqueous solution. The μ-X-ray absorption near edge spectroscopic (μ-XANES) analyses indicated HgS as a major mercury species, and suggested that the intra-particle mercury transport involved a chemical reaction with PSR polymer. An intra-particle mass transfer model was developed based on either a Langmuir sorption isotherm with liquid phase diffusion (Langmuir model) or a kinetic sorption with surface diffusion (kinetic sorption model). The Langmuir model predicted the general trend of mercury diffusion, although at a slower rate than observed from the μ-XRF map. A kinetic sorption model suggested faster mercury transport, which overestimated the movement of mercuric ions through an exchange reaction between the fast and slow reaction sites. Both μ-XRF and mathematical modeling results suggest mercury removal occurs not only at the outer surface of the PSR-AC particle but also at some interior regions due to a large PSR surface area within an AC particle. PMID:22133913

  11. Method of producing carbon coated nano- and micron-scale particles

    DOEpatents

    Perry, W. Lee; Weigle, John C; Phillips, Jonathan

    2013-12-17

    A method of making carbon-coated nano- or micron-scale particles comprising entraining particles in an aerosol gas, providing a carbon-containing gas, providing a plasma gas, mixing the aerosol gas, the carbon-containing gas, and the plasma gas proximate a torch, bombarding the mixed gases with microwaves, and collecting resulting carbon-coated nano- or micron-scale particles.

  12. Temporal succession in carbon incorporation from macromolecules by particle-attached bacteria in marine microcosms: Particle-attached bacteria incorporating organic carbon

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Mayali, Xavier; Stewart, Benjamin; Mabery, Shalini

    Here, we investigated bacterial carbon assimilation from stable isotope-labelled macromolecular substrates (proteins; lipids; and two types of polysaccharides, starch and cellobiose) while attached to killed diatom detrital particles during laboratory microcosms incubated for 17 days. Using Chip-SIP (secondary ion mass spectrometry analysis of RNA microarrays), we identified generalist operational taxonomic units (OTUs) from the Gammaproteobacteria, belonging to the genera Colwellia, Glaciecola, Pseudoalteromonas and Rheinheimera, and from the Bacteroidetes, genera Owenweeksia and Maribacter, that incorporated the four tested substrates throughout the incubation period. Many of these OTUs exhibited the highest isotope incorporation relative to the others, indicating that they were likelymore » the most active. Additional OTUs from the Gammaproteobacteria, Bacteroidetes and Alphaproteobacteria exhibited generally (but not always) lower activity and did not incorporate all tested substrates at all times, showing species succession in organic carbon incorporation. We also found evidence to suggest that both generalist and specialist OTUs changed their relative substrate incorporation over time, presumably in response to changing substrate availability as the particles aged. This pattern was demonstrated by temporal succession from relatively higher starch incorporation early in the incubations, eventually switching to higher cellobiose incorporation after 2 weeks.« less

  13. Ignition of a Combustible Atmosphere by Incandescent Carbon Wear Particles

    NASA Technical Reports Server (NTRS)

    Buckley, Donald H.; Swikert, Max A.; Johnson, Robert L.

    1960-01-01

    A study was made to determine whether carbon wear particles from carbon elements in sliding contact with a metal surface were sufficiently hot to cause ignition of a combustible atmosphere. In some machinery, electric potential differences and currents may appear at the carbon-metal interface. For this reason the effect of these voltages and currents on the ability of carbon wear particles to cause ignition was evaluated. The test specimens used in the investigation were carbon vanes taken from a fuel pump and flat 21-inch-diameter 2 metal disks (440-C stainless steel) representing the pump housing. During each experiment a vane was loaded against a disk with a 0.5-pound force, and the disk was rotated to give a surface speed of 3140 feet per minute. The chamber of the apparatus that housed the vane and the disk was filled with a combustible mixture of air and propane. Various voltages and amperages were applied across the vane-disk interface. Experiments were conducted at temperatures of 75, 350, 400, and 450 F. Fires were produced by incandescent carbon wear particles obtained at conditions of electric potential as low as 106 volts and 0.3 ampere at 400 F. Ignitions were obtained only with carbon wear particles produced with an electric potential across the carbon-vane-disk interface. No ignitions were obtained with carbon wear particles produced in the absence of this potential; also, the potential difference produced no ignitions in the absence of carbon wear particles. A film supplement showing ignition by incandescent wear particles is available.

  14. Effect of the relationship between particle size, inter-particle distance, and metal loading of carbon supported fuel cell catalysts on their catalytic activity

    NASA Astrophysics Data System (ADS)

    Corradini, Patricia Gon; Pires, Felipe I.; Paganin, Valdecir A.; Perez, Joelma; Antolini, Ermete

    2012-09-01

    The effect of the relationship between particle size ( d), inter-particle distance ( x i ), and metal loading ( y) of carbon supported fuel cell Pt or PtRu catalysts on their catalytic activity, based on the optimum d (2.5-3 nm) and x i / d (>5) values, was evaluated. It was found that for y < 30 wt%, the optimum values of both d and x i / d can be always obtained. For y ≥ 30 wt%, instead, the positive effect of a thinner catalyst layer of the fuel cell electrode than that using catalysts with y < 30 wt% is concomitant to a decrease of the effective catalyst surface area due to an increase of d and/or a decrease of x i / d compared to their optimum values, with in turns gives rise to a decrease in the catalytic activity. The effect of the x i / d ratio has been successfully verified by experimental results on ethanol oxidation on PtRu/C catalysts with same particle size and same degree of alloying but different metal loading. Tests in direct ethanol fuel cells showed that, compared to 20 wt% PtRu/C, the negative effect of the lower x i / d on the catalytic activity of 30 and 40 wt% PtRu/C catalysts was superior to the positive effect of the thinner catalyst layer.

  15. Platinum particle size and support effects in NO(x) mediated carbon oxidation over platinum catalysts.

    PubMed

    Villani, Kenneth; Vermandel, Walter; Smets, Koen; Liang, Duoduo; van Tendeloo, Gustaaf; Martens, Johan A

    2006-04-15

    Platinum metal was dispersed on microporous, mesoporous, and nonporous support materials including the zeolites Na-Y, Ba-Y, Ferrierite, ZSM-22, ETS-10, and AIPO-11, alumina, and titania. The oxidation of carbon black loosely mixed with catalyst powder was monitored gravimetrically in a gas stream containing nitric oxide, oxygen, and water. The carbon oxidation activity of the catalysts was found to be uniquely related to the Pt dispersion and little influenced by support type. The optimum dispersion is around 3-4% corresponding to relatively large Pt particle sizes of 20-40 nm. The carbon oxidation activity reflects the NO oxidation activity of the platinum catalyst, which reaches an optimum in the 20-40 nm Pt particle size range. The lowest carbon oxidation temperatures were achieved with platinum loaded ZSM-22 and AIPO-11 zeolite crystallites bearing platinum of optimum dispersion on their external surfaces.

  16. Trivalent chromium removal from wastewater using low cost activated carbon derived from agricultural waste material and activated carbon fabric cloth.

    PubMed

    Mohan, Dinesh; Singh, Kunwar P; Singh, Vinod K

    2006-07-31

    An efficient adsorption process is developed for the decontamination of trivalent chromium from tannery effluents. A low cost activated carbon (ATFAC) was prepared from coconut shell fibers (an agricultural waste), characterized and utilized for Cr(III) removal from water/wastewater. A commercially available activated carbon fabric cloth (ACF) was also studied for comparative evaluation. All the equilibrium and kinetic studies were conducted at different temperatures, particle size, pHs, and adsorbent doses in batch mode. The Langmuir and Freundlich isotherm models were applied. The Langmuir model best fit the equilibrium isotherm data. The maximum adsorption capacities of ATFAC and ACF at 25 degrees C are 12.2 and 39.56 mg/g, respectively. Cr(III) adsorption increased with an increase in temperature (10 degrees C: ATFAC--10.97 mg/g, ACF--36.05 mg/g; 40 degrees C: ATFAC--16.10 mg/g, ACF--40.29 mg/g). The kinetic studies were conducted to delineate the effect of temperature, initial adsorbate concentration, particle size of the adsorbent, and solid to liquid ratio. The adsorption of Cr(III) follows the pseudo-second-order rate kinetics. From kinetic studies various rate and thermodynamic parameters such as effective diffusion coefficient, activation energy and entropy of activation were evaluated. The sorption capacity of activated carbon (ATFAC) and activated carbon fabric cloth is comparable to many other adsorbents/carbons/biosorbents utilized for the removal of trivalent chromium from water/wastewater.

  17. Structure and properties of carbon black particles

    NASA Astrophysics Data System (ADS)

    Xu, Wei

    Structure and properties of carbon black particles were investigated using atomic force microscopy, gas adsorption, Raman spectroscopy, and X-ray diffraction. Supplementary information was obtained using TEM and neutron scattering. The AFM imaging of carbon black aggregates provided qualitative visual information on their morphology, complementary to that obtained by 3-D modeling based on TEM images. Our studies showed that carbon black aggregates were relatively flat. The surface of all untreated carbon black particles was found to be rough and its fractal dimension was 2.2. Heating reduced the roughness and fractal dimension for all samples heat treated at above 1300 K to 2.0. Once the samples were heat treated rapid cooling did not affect the surface roughness. However, rapid cooling reduced crystallite sizes, and different Raman spectra were obtained for carbon blacks of various history of heat treatment. By analyzing the Raman spectra we determined the crystallite sizes and identified amorphous carbon. The concentration of amorphous carbon depends on hydrogen content. Once hydrogen was liberated at increased temperature, the concentration of amorphous carbon was reduced and crystallites started to grow. Properties of carbon blacks at high pressure were also studied. Hydrostatic pressure did not affect the size of the crystallites in carbon black particles. The pressure induced shift in Raman frequency of the graphitic component was a result of increased intermolecular forces and not smaller crystallites. Two methods of determining the fractal dimension, the FHH model and the yardstick technique based on the BET theory were used in the literature. Our study proved that the FHH model is sensitive to numerous assumptions and leads to wrong conclusions. On the other hand the yardstick method gave correct results, which agreed with the AFM results.

  18. Preparation of steam activated carbon from rubberwood sawdust (Hevea brasiliensis) and its adsorption kinetics.

    PubMed

    Prakash Kumar, B G; Shivakamy, K; Miranda, Lima Rose; Velan, M

    2006-08-25

    Activated carbon was produced from a biowaste product, rubberwood sawdust (RWSD) using steam in a high temperature fluidized bed reactor. Experiments were carried out to investigate the influence of various process parameters such as activation time, activation temperature, particle size and fluidising velocity on the quality of the activated carbon. The activated carbon was characterized based on its iodine number, methylene blue number, Brauner Emmet Teller (BET) surface area and surface area obtained using the ethylene glycol mono ethyl ether (EGME) retention method. The best quality activated carbon was obtained at an activation time and temperature of 1h and 750 degrees C for an average particle size of 0.46 mm. The adsorption kinetics shows that pseudo-second-order rate fitted the adsorption kinetics better than pseudo-first-order rate equation. The adsorption capacity of carbon produced from RWSD was found to be 1250 mg g(-1) for the Bismark Brown dye. The rate constant and diffusion coefficient for intraparticle transport were determined for steam activated carbon. The characteristic of the prepared activated carbon was found comparable to the commercial activated carbon.

  19. Quantitative high-resolution mapping of phenanthrene sorption to black carbon particles.

    PubMed

    Obst, Martin; Grathwohl, Peter; Kappler, Andreas; Eibl, Oliver; Peranio, Nicola; Gocht, Tilman

    2011-09-01

    Sorption of hydrophobic organic contaminants such as polycyclic aromatic hydrocarbons (PAHs) to black carbon (BC) particles has been the focus of numerous studies. Conclusions on sorption mechanisms of PAH on BC were mostly derived from studies of sorption isotherms and sorption kinetics, which are based on batch experiments. However, mechanistic modeling approaches consider processes at the subparticle scale, some including transport within the pore-space or different spatial pore-domains. Direct evidence based on analytical techniques operating at the submicrometer scale for the location of sorption sites and the adsorbed species is lacking. In this work, we identified, quantified, and mapped the sorption of PAHs on different BC particles (activated carbon, charcoal and diesel soot) on a 25-100 nm scale using scanning transmission X-ray microscopy (STXM). In addition, we visualized the pore structure of the particles by transmission electron microscopy (TEM) on the 1-10 nm-scale. The combination of the chemical information from STXM with the physical information from TEM revealed that phenanthrene accumulates in the interconnected pore-system along primary "cracks" in the particles, confirming an adsorption mechanism.

  20. Physicochemical characteristics and toxic effects of ozone-oxidized black carbon particles

    NASA Astrophysics Data System (ADS)

    Li, Qian; Shang, Jing; Zhu, Tong

    2013-12-01

    Black carbon (BC) or soot particles formed by combustion are ubiquitous in the atmosphere and have a significant effect on climate and human health. Oxidation can change the physicochemical characteristics of BC, thereby increasing its toxicity. The physicochemical properties of BC and ozone-oxidized BC are investigated in this study through transmission electron microscopy, X-ray photoelectron spectroscopy, diffuse reflectance infrared Fourier transform spectroscopy, ultraviolet-visible spectrophotometry, and electron paramagnetic resonance. The contents of oxygen-containing functional groups, hydrophilicity, water-soluble organic compounds, and free radicals increased after ozone treatment. The redox capacity and cytotoxicity of BC particles were enhanced by ozone oxidation as detected by dithiothreitol (DTT) and 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide assays. The redox activities of different BC particles are compared. Particle phase contributed significantly to total redox activity as detected by the DTT assay. Results indicate that BC particles that have undergone aging in the atmosphere may be more toxic and harmful to human health.

  1. Characterization of diesel particles: effects of fuel reformulation, exhaust aftertreatment, and engine operation on particle carbon composition and volatility.

    PubMed

    Alander, Timo J A; Leskinen, Ari P; Raunemaa, Taisto M; Rantanen, Leena

    2004-05-01

    Diesel exhaust particles are the major constituent of urban carbonaceous aerosol being linked to a large range of adverse environmental and health effects. In this work, the effects of fuel reformulation, oxidation catalyst, engine type, and engine operation parameters on diesel particle emission characteristics were investigated. Particle emissions from an indirect injection (IDI) and a direct injection (DI) engine car operating under steady-state conditions with a reformulated low-sulfur, low-aromatic fuel and a standard-grade fuel were analyzed. Organic (OC) and elemental (EC) carbon fractions of the particles were quantified by a thermal-optical transmission analysis method and particle size distributions measured with a scanning mobility particle sizer (SMPS). The particle volatility characteristics were studied with a configuration that consisted of a thermal desorption unit and an SMPS. In addition, the volatility of size-selected particles was determined with a tandem differential mobility analyzer technique. The reformulated fuel was found to produce 10-40% less particulate carbon mass compared to the standard fuel. On the basis of the carbon analysis, the organic carbon contributed 27-61% to the carbon mass of the IDI engine particle emissions, depending on the fuel and engine operation parameters. The fuel reformulation reduced the particulate organic carbon emissions by 10-55%. In the particles of the DI engine, the organic carbon contributed 14-26% to the total carbon emissions, the advanced engine technology, and the oxidation catalyst, thus reducing the OC/EC ratio of particles considerably. A relatively good consistency between the particulate organic fraction quantified with the thermal optical method and the volatile fraction measured with the thermal desorption unit and SMPS was found.

  2. Synthesis and electrochemical performances of amorphous carbon-coated Sn Sb particles as anode material for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Wang, Zhong; Tian, Wenhuai; Liu, Xiaohe; Yang, Rong; Li, Xingguo

    2007-12-01

    The amorphous carbon coating on the Sn-Sb particles was prepared from aqueous glucose solutions using a hydrothermal method. Because the outer layer carbon of composite materials is loose cotton-like and porous-like, it can accommodate the expansion and contraction of active materials to maintain the stability of the structure, and hinder effectively the aggregation of nano-sized alloy particles. The as-prepared composite materials show much improved electrochemical performances as anode materials for lithium-ion batteries compared with Sn-Sb alloy and carbon alone. This amorphous carbon-coated Sn-Sb particle is extremely promising anode materials for lithium secondary batteries and has a high potentiality in the future use.

  3. The Diversity of Carbon in Cometary Refractory Dust Particles

    NASA Technical Reports Server (NTRS)

    Wooden, D. H.

    2018-01-01

    When comparing the dark icy surfaces of outer solar system small bodies and the composition of carbonaceous chondrites derived from dark asteroids we find a significant discrepancy in the assessed amounts of elemental carbon: up to 80% amorphous carbon is used to model the dark surfaces of Kuiper Belt Objects and Centaurs whereas at most 5% of elemental carbon is found in carbonaceous chondrites. If we presume that regimes of comet nuclei formation are analogous to disk regimes where other outer solar system ice-rich bodies formed then we can turn to comet dust to gain insights into the diversity in the concentration and forms of carbon available in the outer disk. Comet dust offers important insights into the diversity in the amounts and forms of carbon that were incorporated into aggregate dust particles in the colder parts of the protoplanetary disk out of which comet nuclei accreted. Comet nuclei are amongst the most primitive bodies because they have remained cold and unequilibrated. Comet dust particles reveal the presence of forms of elemental carbon and of soluble and insoluble organic matter, and in a great diversity of concentrations from very little, e.g., Stardust samples of comet 81P/Wild 2, to 80% by volume for Ultra Carbonaceous Antarctic Micro Meteorites (UCAMMs). Cometary outbursts and/or jet activity also demonstrate variations in the concentration of carbon in the grains at different grain sizes within a single comet. We review the diversity of carbon-bearing dust grains in cometary samples, flyby measurements and deduced from remote-sensing to enrich the discussion about the diversity of carbonaceous matter available in the outer ice-rich disk at the time of comet nuclei formation.

  4. Preparation and characterization of carbonic anhydrase-conjugated liposomes for catalytic synthesis of calcium carbonate particles.

    PubMed

    Maeshima, Keisuke; Yoshimoto, Makoto

    2017-10-01

    The biomimetic approach using immobilized enzymes is useful for the synthesis of structurally defined inorganic materials. In this work, carbonic anhydrase (CA) from bovine erythrocytes was covalently conjugated at 25°C to the liposomes composed of 15mol% 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine-N-(glutaryl) (NG-POPE), and the zwitterionic and anionic phospholipids with the same acyl chains as NG-POPE. For the conjugation, the carboxyl groups of liposomal NG-POPE were activated with 11mM 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) and 4.6mM N-hydroxysulfosuccinimide (sulfo-NHS). The carbonic anhydrase-conjugated liposomes (CALs) with the mean hydrodynamic diameter of 149nm showed the esterase activity corresponding to on average 5.5×10 2 free CA molecules per liposome. On the other hand, the intrinsic fluorescence and absorbance measurements consistently revealed that on average 1.4×10 3 CA molecules were conjugated to a liposome, suggesting that the molecular orientation of enzyme affected its activity. The formation of calcium carbonate particles was significantly accelerated by the CALs ([lipid]=50μ M) in the 0.3M Tris solution at 10-40°C with dissolved CO 2 (≈17mM) and CaCl 2 (46mM). The anionic CALs were adsorbed with calcium as revealed with the ζ-potential measurements. The CAL system offered the calcium-rich colloidal interface where the bicarbonate ions were catalytically produced by the liposome-conjugated CA molecules. The CALs also functioned in the external loop airlift bubble column operated with a model flue gas (10vol/vo% CO 2 ), yielding partly agglomerated calcium carbonate particles as observed with the scanning electron microscopy (SEM). Copyright © 2017 Elsevier Inc. All rights reserved.

  5. Filterable redox cycling activity: a comparison between diesel exhaust particles and secondary organic aerosol constituents.

    PubMed

    McWhinney, Robert D; Badali, Kaitlin; Liggio, John; Li, Shao-Meng; Abbatt, Jonathan P D

    2013-04-02

    The redox activity of diesel exhaust particles (DEP) collected from a light-duty diesel passenger car engine was examined using the dithiothreitol (DTT) assay. DEP was highly redox-active, causing DTT to decay at a rate of 23-61 pmol min(-1) μg(-1) of particle used in the assay, which was an order of magnitude higher than ambient coarse and fine particulate matter (PM) collected from downtown Toronto. Only 2-11% of the redox activity was in the water-soluble portion, while the remainder occurred at the black carbon surface. This is in contrast to redox-active secondary organic aerosol constituents, in which upward of 90% of the activity occurs in the water-soluble fraction. The redox activity of DEP is not extractable by moderately polar (methanol) and nonpolar (dichloromethane) organic solvents, and is hypothesized to arise from redox-active moieties contiguous with the black carbon portion of the particles. These measurements illustrate that "Filterable Redox Cycling Activity" may therefore be useful to distinguish black carbon-based oxidative capacity from water-soluble organic-based activity. The difference in chemical environment leading to redox activity highlights the need to further examine the relationship between activity in the DTT assay and toxicology measurements across particles of different origins and composition.

  6. Quality of poultry litter-derived granular activated carbon.

    PubMed

    Qiu, Guannan; Guo, Mingxin

    2010-01-01

    Utilization of poultry litter as a source material for generating activated carbon is a value-added and environmentally beneficial approach to recycling organic waste. In this study, the overall quality of poultry litter-derived granular activated carbon was systematically evaluated based on its various physical and chemical properties. Granular activated carbon generated from pelletized poultry litter following a typical steam-activation procedure possessed numerous micropores in the matrix. The product exhibited a mean particle diameter of 2.59 mm, an apparent density of 0.45 g cm(-3), a ball-pan hardness of 91.0, an iodine number of 454 mg g(-1), and a BET surface area of 403 m(2) g(-1). It contained high ash, nitrogen, phosphorus contents and the trace elements Cu, Zn, and As. Most of the nutrients and toxic elements were solidified and solution-unextractable. In general, poultry litter-based activated carbon demonstrated overall quality comparable to that of low-grade commercial activated carbon derived from coconut shell and bituminous coal. It is promising to use poultry litter as a feedstock to manufacture activated carbon for wastewater treatment.

  7. Application of Biofilm Covered Activated Carbon Particles as a Microbial Inoculum Delivery System for Enhanced Bioaugmentation of PCBs in Contaminated Sediment

    DTIC Science & Technology

    2013-09-01

    after anaerobic digestion at thermophilic conditions (60- 70C). Application of biofilm covered activated carbon particles as a microbial inoculum...Sludge Thickener; Sludge = Sludge after anaerobic digestion at thermophilic conditions (60- 70C). C3. Microscopic evaluation of dechlorinating...associated enzymes are capable of opening the biphenyl ring structure and transform the molecule into a linear structure, this changed structure was not

  8. [Worker exposure to ultrafine particles during carbon black treatment].

    PubMed

    Mikołajczyk, Urszula; Bujak-Pietrek, Stella; Szadkowska-Stańczyk, Irena

    2015-01-01

    The aim of the project was to assess the exposure of workers to ultrafine particles released during handling and packing of carbon black. The assessment included the results of the measurements performed in a carbon black handling plant before, during, and after work shift. The number concentration of particles within the dimension range 10-1000 nm and 10-100 nm was assayed by a condensation particle counter (CPC). The mass concentration of particles was determined by a DustTrak II DRX aerosol concentration monitor. The surface area concentration of the particles potentially deposited in the alveolar (A) and tracheo-bronchial (TB) regions was estimated by an AeroTrak 9000 nanoparticle monitor. An average mass concentration of particles during the process was 6-fold higher than that before its start, while a 3-fold increase in the average number concentration of particles within the dimension range 10-1000 nm and 10-100 nm was observed during the process. At the same time a 4-fold increase was found in the surface area concentration of the particles potentially deposited in the A and TB regions. During the process of carbon black handling and packing a significantly higher values of each of the analysed parameters, characterizing the exposure to ultrafine particles, were noted. This work is available in Open Access model and licensed under a CC BY-NC 3.0 PL license.

  9. Investigation of refractory black carbon-containing particle morphologies using the single-particle soot photometer (SP2)

    DOE PAGES

    Sedlacek, III, Arthur J.; Lewis, Ernie R.; Onasch, Timothy B.; ...

    2015-07-24

    An important source of uncertainty in radiative forcing by absorbing aerosol particles is the uncertainty in their morphologies (i.e., the location of the absorbing substance on/in the particles). To examine the effects of particle morphology on the response of an individual black carbon-containing particle in a Single-Particle Soot Photometer (SP2), a series of experiments was conducted to investigate black carbon-containing particles of known morphology using Regal black (RB), a proxy for collapsed soot, as the light-absorbing substance. Particles were formed by coagulation of RB with either a solid substance (sodium chloride or ammonium sulfate) or a liquid substance (dioctyl sebacate),more » and by condensation with dioctyl sebacate, the latter experiment forming particles in a core-shell configuration. Each particle type experienced fragmentation (observed as negative lagtimes), and each yielded similar lagtime responses in some instances, confounding attempts to differentiate particle morphology using current SP2 lagtime analysis. SP2 operating conditions, specifically laser power and sample flow rate, which in turn affect the particle heating and dissipation rates, play an important role in the behavior of particles in the SP2, including probability of fragmentation. This behavior also depended on the morphology of the particles and on the thermo-chemical properties of the non-RB substance. Although these influences cannot currently be unambiguously separated, the SP2 analysis may still provide useful information on particle mixing states and black carbon particle sources.« less

  10. Removal of benzocaine from water by filtration with activated carbon

    USGS Publications Warehouse

    Howe, G.E.; Bills, T.D.; Marking, L.L.

    1990-01-01

    Benzocaine is a promising candidate for registration with the U.S. Food and Drug Administration for use as an anesthetic in fish culture, management, and research. A method for the removal of benzocaine from hatchery effluents could speed registration of this drug by eliminating requirements for data on its residues, tolerances, detoxification, and environmental hazards. Carbon filtration effectively removes many organic compounds from water. This study tested the effectiveness of three types of activated carbon for removing benzocaine from water by column filtration under controlled laboratory conditions. An adsorptive capacity was calculated for each type of activated carbon. Filtrasorb 400 (12 x 40 mesh; U.S. standard sieve series) showed the greatest capacity for benzocaine adsorption (76.12 mg benzocaine/g carbon); Filtrasorb 300 (8 x 30 mesh) ranked next (31.93 mg/g); and Filtrasorb 816 (8 x 16 mesh) absorbed the least (1.0 mg/g). Increased adsorptive capacity was associated with smaller carbon particle size; however, smaller particle size also impeded column flow. Carbon filtration is a practical means for removing benzocaine from treated water.

  11. Functional Carbon Nanofibers with Semi-Embedded Titanium Oxide Particles via Electrospinning.

    PubMed

    Chang, Guoqing; Ullah, Wajid; Hu, Yunfeng; Lin, Liwei; Wang, Xu; Li, Chang-Zhi

    2018-05-22

    The formulation of optoelectronic components into 1D nanostructures allows the promotion of new materials with multifunctionalities. In this work, it is demonstrated that new synthesis of photocatalytic carbon nanofiber decorated with semi-embedded titanium oxide (TiO 2 ), namely, TiO 2 @carbon fiber, is conveniently accessed through the electrospinning of polyacrylonitrile polymer and TiO 2 particle comixture, and then followed by photon-activated self-erosion to expose the embedded TiO 2 and carbonization. The hybrid nanofibers are characterized by field emission scanning electron microscopy, transmission electron microscopy, and X-ray diffraction analysis. Furthermore, the photocatalytic activities of the resultant fibers are tested with photodegradation of Rhodamine B in aqueous solution, which reveals that the carbon nanofiber with semi-embedded TiO 2 drastically improved catalytic efficiency and recyclability, comparing to those fibers without or with embedded TiO 2 . © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Method for applying pyrolytic carbon coatings to small particles

    DOEpatents

    Beatty, Ronald L.; Kiplinger, Dale V.; Chilcoat, Bill R.

    1977-01-01

    A method for coating small diameter, low density particles with pyrolytic carbon is provided by fluidizing a bed of particles wherein at least 50 per cent of the particles have a density and diameter of at least two times the remainder of the particles and thereafter recovering the small diameter and coated particles.

  13. Catalytic Growth of Macroscopic Carbon Nanofibers Bodies with Activated Carbon

    NASA Astrophysics Data System (ADS)

    Abdullah, N.; Rinaldi, A.; Muhammad, I. S.; Hamid, S. B. Abd.; Su, D. S.; Schlogl, R.

    2009-06-01

    Carbon-carbon composite of activated carbon and carbon nanofibers have been synthesized by growing Carbon nanofiber (CNF) on Palm shell-based Activated carbon (AC) with Ni catalyst. The composites are in an agglomerated shape due to the entanglement of the defective CNF between the AC particles forming a macroscopic body. The macroscopic size will allow the composite to be used as a stabile catalyst support and liquid adsorbent. The preparation of CNT/AC nanocarbon was initiated by pre-treating the activated carbon with nitric acid, followed by impregnation of 1 wt% loading of nickel (II) nitrate solutions in acetone. The catalyst precursor was calcined and reduced at 300° C for an hour in each step. The catalytic growth of nanocarbon in C2H4/H2 was carried out at temperature of 550° C for 2 hrs with different rotating angle in the fluidization system. SEM and N2 isotherms show the level of agglomeration which is a function of growth density and fluidization of the system. The effect of fluidization by rotating the reactor during growth with different speed give a significant impact on the agglomeration of the final CNF/AC composite and thus the amount of CNFs produced. The macrostructure body produced in this work of CNF/AC composite will have advantages in the adsorbent and catalyst support application, due to the mechanical and chemical properties of the material.

  14. Particles of spilled oil-absorbing carbon in contact with water

    DOEpatents

    Muradov, Nazim [Melbourne, FL

    2011-03-29

    Hydrogen generator coupled to or integrated with a fuel cell for portable power applications. Hydrogen is produced via thermocatalytic decomposition (cracking, pyrolysis) of hydrocarbon fuels in oxidant-free environment. The apparatus can utilize a variety of hydrocarbon fuels, including natural gas, propane, gasoline, kerosene, diesel fuel, crude oil (including sulfurous fuels). The hydrogen-rich gas produced is free of carbon oxides or other reactive impurities, so it could be directly fed to any type of a fuel cell. The catalysts for hydrogen production in the apparatus are carbon-based or metal-based materials and doped, if necessary, with a sulfur-capturing agent. Additionally disclosed are two novel processes for the production of two types of carbon filaments, and a novel filamentous carbon product. Carbon particles with surface filaments having a hydrophobic property of oil film absorption, compositions of matter containing those particles, and a system for using the carbon particles for cleaning oil spills.

  15. Adsorption of aqueous Cd(II) and Pb(II) on activated carbon nanopores prepared by chemical activation of doum palm shell.

    PubMed

    Gaya, Umar Ibrahim; Otene, Emmanuel; Abdullah, Abdul Halim

    2015-01-01

    Non-uniformly sized activated carbons were derived from doum palm shell, a new precursor, by carbonization in air and activation using KOH, NaOH and ZnCl2. The activated carbon fibres were characterised by X-ray diffraction, N2 adsorption-desorption, scanning electron microscopy, particle size analysis and evaluated for Cd(II) and Pb(II) removal. The 40-50 nm size, less graphitic, mesoporous NaOH activated carbon yielded high adsorption efficiency, pointing largely to the influence surface area. The performance of the KOH based activated carbon was arguably explained for the first time in terms of crystallinity. The efficiencies of the mesoporous ZnCl2-formulated activated carbon diminished due to the presence of larger particles. Batch adsorption of divalent metals revealed dependence on adsorbent dose, agitation time, pH and adsorbate concentrations with high adsorption efficiencies at optimum operating parameters. The equilibrium profiles fitted Langmuir and Freundlich isotherms, and kinetics favoured pseudo-second order model. The study demonstrated the practicability of the removal of alarming levels of cadmium and lead ions from industrial effluents.

  16. Effects of decreasing activated carbon particle diameter from 30 μm to 140 nm on equilibrium adsorption capacity.

    PubMed

    Pan, Long; Nishimura, Yuki; Takaesu, Hideki; Matsui, Yoshihiko; Matsushita, Taku; Shirasaki, Nobutaka

    2017-11-01

    The capacity of activated carbon particles with median diameters (D50s) of >∼1 μm for adsorption of hydrophobic micropollutants such as 2-methylisolborneol (MIB) increases with decreasing particle size because the pollutants are adsorbed mostly on the exterior (shell) of the particles owing to the limited diffusion penetration depth. However, particles with D50s of <1 μm have not been thoroughly investigated. Here, we prepared particles with D50s of ∼30 μm-∼140 nm and evaluated their adsorption capacities for MIB and several other environmentally relevant adsorbates. The adsorption capacities for low-molecular-weight adsorbates, including MIB, deceased with decreasing particle size for D50s of less than a few micrometers, whereas adsorption capacities increased with decreasing particle size for larger particles. The oxygen content of the particles increased substantially with decreasing particle size for D50s of less than a few micrometers, and oxygen content was negatively correlated with adsorption capacity. The decrease in adsorption capacity with decreasing particle size for the smaller particles was due to particle oxidation during the micromilling procedure used to decrease D50 to ∼140 nm. When oxidation was partially inhibited, the MIB adsorption capacity decrease was attenuated. For high-molecular-weight adsorbates, adsorption capacity increased with decreasing particle size over the entire range of tested particle sizes, even though particle oxygen content increased with decreasing particle size. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Particle size analysis on density, surface morphology and specific capacitance of carbon electrode from rubber wood sawdust

    NASA Astrophysics Data System (ADS)

    Taer, E.; Kurniasih, B.; Sari, F. P.; Zulkifli, Taslim, R.; Sugianto, Purnama, A.; Apriwandi, Susanti, Y.

    2018-02-01

    The particle size analysis for supercapacitor carbon electrodes from rubber wood sawdust (SGKK) has been done successfully. The electrode particle size was reviewed against the properties such as density, degree of crystallinity, surface morphology and specific capacitance. The variations in particle size were made by different treatment on the grinding and sieving process. The sample particle size was distinguished as 53-100 µm for 20 h (SA), 38-53 µm for 20 h (SB) and < 38 µm with variations of grinding time for 40 h (SC) and 80 h (SD) respectively. All of the samples were activated by 0.4 M KOH solution. Carbon electrodes were carbonized at temperature of 600oC in N2 gas environment and then followed by CO2 gas activation at a temperature of 900oC for 2 h. The densities for each variation in the particle size were 1.034 g cm-3, 0.849 g cm-3, 0.892 g cm-3 and 0.982 g cm-3 respectively. The morphological study identified the distance between the particles more closely at 38-53 µm (SB) particle size. The electrochemical properties of supercapacitor cells have been investigated using electrochemical methods such as impedance spectroscopy and charge-discharge at constant current using Solatron 1280 tools. Electrochemical properties testing results have shown SB samples with a particle size of 38-53 µm produce supercapacitor cells with optimum capacitive performance.

  18. Biological uptake of polychlorinated biphenyls by Macoma balthica from sediment amended with activated carbon

    USGS Publications Warehouse

    McLeod, Pamela B.; van den Heuvel-Greve, Martine J.; Luoma, S.N.; Luthy, R.G.

    2007-01-01

    This work characterizes the efficacy of activated carbon amendment in reducing polychlorinated biphenyl (PCB) bioavailability to clams (Macoma balthica) from field-contaminated sediment (Hunters Point Naval Shipyard, San Francisco Bay, CA, USA) Test methods were developed for the use of clams to investigate the effects of sediment amendment on biological uptake. Sediment was mixed with activated carbon for one month. Bioaccumulation tests (28 d) were employed to assess the relationships between carbon dose and carbon particle size on observed reductions in clam biological uptake of PCBs. Extraction and cleanup protocols were developed for the clam tissue. Efficacy of activated carbon treatment was found to increase with both increasing carbon dose and decreasing carbon particle size. Average reductions in bioaccumulation of 22, 64, and 84% relative to untreated Hunters Point sediment were observed for carbon amendments of 0.34, 1.7, and 3.4%, respectively. Average bioaccumulation reductions of 41, 73, and 89% were observed for amendments (dose = 1.7% dry wt) with carbon particles of 180 to 250, 75 to 180, and 25 to 75 ??m, respectively, in diameter, indicating kinetic phenomena in these tests. Additionally, a biodynamic model quantifying clam PCB uptake from water and sediment as well as loss through elimination provided a good fit of experimental data. Model predictions suggest that the sediment ingestion route contributed 80 to 95% of the PCB burdens in the clams. ?? 2007 SETAC.

  19. Process for producing an activated carbon adsorbent with integral heat transfer apparatus

    NASA Technical Reports Server (NTRS)

    Jones, Jack A. (Inventor); Yavrouian, Andre H. (Inventor)

    1996-01-01

    A process for producing an integral adsorbent-heat exchanger apparatus useful in ammonia refrigerant heat pump systems. In one embodiment, the process wets an activated carbon particles-solvent mixture with a binder-solvent mixture, presses the binder wetted activated carbon mixture on a metal tube surface and thereafter pyrolyzes the mixture to form a bonded activated carbon matrix adjoined to the tube surface. The integral apparatus can be easily and inexpensively produced by the process in large quantities.

  20. Morphology and Optical Properties of Black-Carbon Particles Relevant to Engine Emissions

    NASA Astrophysics Data System (ADS)

    Michelsen, H. A.; Bambha, R.; Dansson, M. A.; Schrader, P. E.

    2013-12-01

    Black-carbon particles are believed to have a large influence on climate through direct radiative forcing, reduction of surface albedo of snow and ice in the cryosphere, and interaction with clouds. The optical properties and morphology of atmospheric particles containing black carbon are uncertain, and characterization of black carbon resulting from engines emissions is needed. Refractory black-carbon particles found in the atmosphere are often coated with unburned fuel, sulfuric acid, water, ash, and other combustion by-products and atmospheric constituents. Coatings can alter the optical and physical properties of the particles and therefore change their optical properties and cloud interactions. Details of particle morphology and coating state can also have important effects on the interpretation of optical diagnostics. A more complete understanding of how coatings affect extinction, absorption, and incandescence measurements is needed before these techniques can be applied reliably to a wide range of particles. We have investigated the effects of coatings on the optical and physical properties of combustion-generated black-carbon particles using a range of standard particle diagnostics, extinction, and time-resolved laser-induced incandescence (LII) measurements. Particles were generated in a co-flow diffusion flame, extracted, cooled, and coated with oleic acid. The diffusion flame produces highly dendritic soot aggregates with similar properties to those produced in diesel engines, diffusion flames, and most natural combustion processes. A thermodenuder was used to remove the coating. A scanning mobility particle sizer (SMPS) was used to monitor aggregate sizes; a centrifugal particle mass analyzer (CPMA) was used to measure coating mass fractions, and transmission electron microscopy (TEM) was used to characterize particle morphologies. The results demonstrate important differences in optical measurements between coated and uncoated particles.

  1. Composite electrodes of activated carbon derived from cassava peel and carbon nanotubes for supercapacitor applications

    NASA Astrophysics Data System (ADS)

    Taer, E.; Iwantono, Yulita, M.; Taslim, R.; Subagio, A.; Salomo, Deraman, M.

    2013-09-01

    In this paper, a composite electrode was prepared from a mixture of activated carbon derived from precarbonization of cassava peel (CP) and carbon nanotubes (CNTs). The activated carbon was produced by pyrolysis process using ZnCl2 as an activation agent. A N2 adsorption-desorption analysis for the sample indicated that the BET surface area of the activated carbon was 1336 m2 g-1. Difference percentage of CNTs of 0, 5, 10, 15 and 20% with 5% of PVDF binder were added into CP based activated carbon in order to fabricate the composite electrodes. The morphology and structure of the composite electrodes were investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. The SEM image observed that the distribution of CNTs was homogeneous between carbon particles and the XRD pattern shown the amorphous structure of the sample. The electrodes were fabricated for supercapacitor cells with 316L stainless steel as current collector and 1 M sulfuric acid as electrolyte. An electrochemical characterization was performed by using an electrochemical impedance spectroscopy (EIS) method using a Solatron 1286 instrument and the addition of CNTs revealed to improve the resistant and capacitive properties of supercapacitor cell.

  2. Morphology and mixing of black carbon particles collected in central California during the CARES field study

    DOE PAGES

    Moffet, Ryan C.; O'Brien, Rachel E.; Alpert, Peter A.; ...

    2016-11-23

    Aerosol absorption is strongly dependent on the internal heterogeneity (mixing state) and morphology of individual particles containing black carbon (BC) and other non-absorbing species. Here, we examine an extensive microscopic data set collected in the California Central Valley during the CARES 2010 field campaign. During a period of high photochemical activity and pollution buildup, the particle mixing state and morphology were characterized using scanning transmission X-ray microscopy (STXM) at the carbon K-edge. Observations of compacted BC core morphologies and thick organic coatings at both urban and rural sites provide evidence of the aged nature of particles, highlighting the importance ofmore » highly aged particles at urban sites during periods of high photochemical activity. Based on the observation of thick coatings and more convex BC inclusion morphology, either the aging was rapid or the contribution of fresh BC emissions at the urban site was relatively small compared to background concentrations. Most particles were observed to have the BC inclusion close to the center of the host. However, host particles containing inorganic rich inclusions had the BC inclusion closer to the edge of the particle. Furthermore, these measurements of BC morphology and mixing state provide important constraints for the morphological effects on BC optical properties expected in aged urban plumes.« less

  3. Morphology and mixing of black carbon particles collected in central California during the CARES field study

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Moffet, Ryan C.; O'Brien, Rachel E.; Alpert, Peter A.

    Aerosol absorption is strongly dependent on the internal heterogeneity (mixing state) and morphology of individual particles containing black carbon (BC) and other non-absorbing species. Here, we examine an extensive microscopic data set collected in the California Central Valley during the CARES 2010 field campaign. During a period of high photochemical activity and pollution buildup, the particle mixing state and morphology were characterized using scanning transmission X-ray microscopy (STXM) at the carbon K-edge. Observations of compacted BC core morphologies and thick organic coatings at both urban and rural sites provide evidence of the aged nature of particles, highlighting the importance ofmore » highly aged particles at urban sites during periods of high photochemical activity. Based on the observation of thick coatings and more convex BC inclusion morphology, either the aging was rapid or the contribution of fresh BC emissions at the urban site was relatively small compared to background concentrations. Most particles were observed to have the BC inclusion close to the center of the host. However, host particles containing inorganic rich inclusions had the BC inclusion closer to the edge of the particle. Furthermore, these measurements of BC morphology and mixing state provide important constraints for the morphological effects on BC optical properties expected in aged urban plumes.« less

  4. Ultraviolet Spectroscopy of Matrix-isolated Amorphous Carbon Particles

    NASA Astrophysics Data System (ADS)

    Schnaiter, M.; Mutschke, H.; Henning, Th.; Lindackers, D.; Strecker, M.; Roth, P.

    1996-06-01

    In view of the interstellar 217.5 nm and the circumstellar 230--250 nm extinction features, the UV extinction behavior of small matrix-isolated amorphous carbon grains is investigated experimentally. The particles were produced in a flame by burning acetylene with oxygen at low pressure. To prevent coagulation, the condensing primary soot grains (average diameter ~6 nm) were extracted by a molecular beam technique into a high-vacuum chamber. There they were deposited into a layer of solid argon, isolated from each other. The particle mass and size were controlled using a particle mass spectrometer. The measured UV extinction of the matrix-isolated particles is compared with measurements on samples produced in the conventional way by collecting carbon smoke on substrate as well as with scattering calculations for small spheres and ellipsoides. The laboratory data give a good representation of the circumstellar extinction feature observed in the spectrum of V348 Sgr.

  5. Entrapment of carbon dioxide with chitosan-based core-shell particles containing changeable cores.

    PubMed

    Dong, Yanrui; Fu, Yinghao; Lin, Xia; Xiao, Congming

    2016-08-01

    Water-soluble chitosan-based core-shell particles that contained changeable cores were successfully applied to anchor carbon dioxide. The entrapment capacity of the particles for carbon dioxide (EC) depended on the cores. It was found that EC of the particles contained aqueous cores was higher than that of the beads with water-soluble chitosan gel cores, which was confirmed with thermogravimetric analysis. In addition, calcium ions and sodium hydroxide were introduced within the particles to examine their effect on the entrapment. EC of the particles was enhanced with sodium hydroxide when the cores were WSC gel. The incorporation of calcium ions was helpful for stabilizing carbon dioxide through the formation of calcium carbonate, which was verified with Fourier transform infrared spectra and scanning electron microscopy/energy-dispersive spectrometry. This phenomenon meant the role of calcium ions for fixating carbon dioxide was significant. Copyright © 2016 Elsevier B.V. All rights reserved.

  6. Erosion of carbon/carbon by solar wind charged particle radiation during a solar probe mission

    NASA Technical Reports Server (NTRS)

    Sokolowski, Witold; O'Donnell, Tim; Millard, Jerry

    1991-01-01

    The possible erosion of a carbon/carbon thermal shield by solar wind-charged particle radiation is reviewed. The present knowledge of erosion data for carbon and/or graphite is surveyed, and an explanation of erosion mechanisms under different charged particle environments is discussed. The highest erosion is expected at four solar radii. Erosion rates are analytically estimated under several conservative assumptions for a normal quiet and worst case solar wind storm conditions. Mass loss analyses and comparison studies surprisingly indicate that the predicted erosion rate by solar wind could be greater than by nominal free sublimation during solar wind storm conditions at four solar radii. The predicted overall mass loss of a carbon/carbon shield material during the critical four solar radii flyby can still meet the mass loss mission requirement of less than 0.0025 g/sec.

  7. Spherical Macroporous Carbon Nanotube Particles with Ultrahigh Sulfur Loading for Lithium-Sulfur Battery Cathodes.

    PubMed

    Gueon, Donghee; Hwang, Jeong Tae; Yang, Seung Bo; Cho, Eunkyung; Sohn, Kwonnam; Yang, Doo-Kyung; Moon, Jun Hyuk

    2018-01-23

    A carbon host capable of effective and uniform sulfur loading is the key for lithium-sulfur batteries (LSBs). Despite the application of porous carbon materials of various morphologies, the carbon hosts capable of uniformly impregnating highly active sulfur is still challenging. To address this issue, we demonstrate a hierarchical pore-structured CNT particle host containing spherical macropores of several hundred nanometers. The macropore CNT particles (M-CNTPs) are prepared by drying the aerosol droplets in which CNTs and polymer particles are dispersed. The spherical macropore greatly improves the penetration of sulfur into the carbon host in the melt diffusion of sulfur. In addition, the formation of macropores greatly develops the volume of the micropore between CNT strands. As a result, we uniformly impregnate 70 wt % sulfur without sulfur residue. The S-M-CNTP cathode shows a highly reversible capacity of 1343 mA h g -1 at a current density of 0.2 C even at a high sulfur content of 70 wt %. Upon a 10-fold current density increase, a high capacity retention of 74% is observed. These cathodes have a higher sulfur content than those of conventional CNT hosts but nevertheless exhibit excellent performance. Our CNTPs and pore control technology will advance the commercialization of CNT hosts for LSBs.

  8. Evaluation on simultaneous removal of particles and off-flavors using population balance for application of powdered activated carbon in dissolved air flotation process.

    PubMed

    Kwak, D H; Yoo, S J; Lee, E J; Lee, J W

    2010-01-01

    Most of the water treatment plants applying the DAF process are faced with off-flavors control problems. For simultaneous control of particles of impurities and dissolved organics that cause pungent taste and odor in water, an effective method would be the simple application of powdered activated carbon (PAC) in the DAF process. A series of experiments were carried out to explore the feasibility for simultaneous removal of kaolin particles and organic compounds that produce off-flavors (2-MIB and geosmin). In addition, the flotation efficiency of kaolin and PAC particles adsorbing organics in the DAF process was evaluated by employing the population balance theory. The removal efficiency of 2-MIB and geosmin under the treatment condition with kaolin particles for simultaneous treatment was lower than that of the individual treatment. The decrease in the removal efficiency was probably caused by 2-MIB and geosmin remaining in the PAC particle in the treated water of DAF after bubble flotation. Simulation results obtained by the population balance model indicate, that the initial collision-attachment efficiency of PAC particles was lower than that of kaolin particles.

  9. Does carbonation of steel slag particles reduce their toxicity? An in vitro approach.

    PubMed

    Ibouraadaten, Saloua; van den Brule, Sybille; Lison, Dominique

    2015-06-01

    Mineral carbonation can stabilize industrial residues and, in the steel industry, may contribute to simultaneously valorize CO2 emissions and slag. We hypothesized that, by restricting the leaching of metals of toxicological concern such as Cr and V, carbonation can suppress the toxicity of these materials. The cytotoxic activity (WST1 assay) of slag dusts collected from a stainless and a Linz-Donawitz (LD) steel plant, before and after carbonation, was examined in J774 macrophages. The release of Cr, V, Fe, Mn and Ni was measured after incubation in artificial lung fluids mimicking the extracellular and phagolysosomal milieu to which particles are confronted after inhalation. LD slag had the higher Fe, Mn and V content, and was more cytotoxic than stainless steel slag. The cytotoxic activity of LD but not of stainless dusts was reduced after carbonation. The cytotoxic activity of the dusts toward J774 macrophages necessitated a direct contact with the cells and was reduced in the presence of inhibitors of phagocytosis (cytochalasin D) or phagolysosome acidification (bafilomycin), pointing to a key role of metallic constituents released in phagolysosomes. This in vitro study supports a limited reduction of the cytotoxic activity of LD, but not of stainless, steel dusts upon carbonation. Copyright © 2015 Elsevier Ltd. All rights reserved.

  10. Flowable Conducting Particle Networks in Redox-Active Electrolytes for Grid Energy Storage

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hatzell, K. B.; Boota, M.; Kumbur, E. C.

    2015-01-01

    This study reports a new hybrid approach toward achieving high volumetric energy and power densities in an electrochemical flow capacitor for grid energy storage. The electrochemical flow capacitor suffers from high self-discharge and low energy density because charge storage is limited to the available surface area (electric double layer charge storage). Here, we examine two carbon materials as conducting particles in a flow battery electrolyte containing the VO2+/VO2+ redox couple. Highly porous activated carbon spheres (CSs) and multi-walled carbon nanotubes (MWCNTs) are investigated as conducting particle networks that facilitate both faradaic and electric double layer charge storage. Charge storage contributionsmore » (electric double layer and faradaic) are distinguished for flow-electrodes composed of MWCNTs and activated CSs. A MWCNT flow-electrode based in a redox-active electrolyte containing the VO2+/VO2+ redox couple demonstrates 18% less self-discharge, 10 X more energy density, and 20 X greater power densities (at 20 mV s-1) than one based on a non-redox active electrolyte. Furthermore, a MWCNT redox-active flow electrode demonstrates 80% capacitance retention, and >95% coulombic efficiency over 100 cycles, indicating the feasibility of utilizing conducting networks with redox chemistries for grid energy storage.« less

  11. Flowable conducting particle networks in redox-active electrolytes for grid energy storage

    DOE PAGES

    Hatzell, K. B.; Boota, M.; Kumbur, E. C.; ...

    2015-01-09

    This paper reports a new hybrid approach toward achieving high volumetric energy and power densities in an electrochemical flow capacitor for grid energy storage. The electrochemical flow capacitor suffers from high self-discharge and low energy density because charge storage is limited to the available surface area (electric double layer charge storage). Here, we examine two carbon materials as conducting particles in a flow battery electrolyte containing the VO 2+/VO 2 + redox couple. Highly porous activated carbon spheres (CSs) and multi-walled carbon nanotubes (MWCNTs) are investigated as conducting particle networks that facilitate both faradaic and electric double layer charge storage.more » Charge storage contributions (electric double layer and faradaic) are distinguished for flow-electrodes composed of MWCNTs and activated CSs. A MWCNT flow-electrode based in a redox-active electrolyte containing the VO 2+/VO 2 + redox couple demonstrates 18% less self-discharge, 10 X more energy density, and 20 X greater power densities (at 20 mV s -1) than one based on a non-redox active electrolyte. Additionally, a MWCNT redox-active flow electrode demonstrates 80% capacitance retention, and >95% coulombic efficiency over 100 cycles, indicating the feasibility of utilizing conducting networks with redox chemistries for grid energy storage.« less

  12. Direct /TEM/ observation of the catalytic oxidation of amorphous carbon by Pd particles

    NASA Technical Reports Server (NTRS)

    Moorhead, R. D.; Poppa, H.; Heinemann, K.

    1980-01-01

    The catalytic oxidation of amorphous carbon substrates by Pd particles is observed by in situ transmission electron microscopy. Various modes of selective attack of the carbon substrate in the immediate neighborhood of Pd particles are observed, which can be correlated with different degrees of particle mobility. Using amorphous substrates we have been able to demonstrate that the particle-substrate interaction is influenced by the structure of the particle. This has not previously been noted.

  13. Source characterization of urban particles from meat smoking activities in Chongqing, China using single particle aerosol mass spectrometry.

    PubMed

    Chen, Yang; Wenger, John C; Yang, Fumo; Cao, Junji; Huang, Rujin; Shi, Guangming; Zhang, Shumin; Tian, Mi; Wang, Huanbo

    2017-09-01

    A Single Particle Aerosol Mass Spectrometer (SPAMS) was deployed in the urban area of Chongqing to characterize the particles present during a severe particulate pollution event that occurred in winter 2014-2015. The measurements were made at a time when residents engaged in traditional outdoor meat smoking activities to preserve meat before the Chinese Spring Festival. The measurement period was predominantly characterized by stagnant weather conditions, highly elevated levels of PM 2.5 , and low visibility. Eleven major single particle types were identified, with over 92.5% of the particles attributed to biomass burning emissions. Most of the particle types showed appreciable signs of aging in the stagnant air conditions. To simulate the meat smoking activities, a series of controlled smoldering experiments was conducted using freshly cut pine and cypress branches, both with and without wood logs. SPAMS data obtained from these experiments revealed a number of biomass burning particle types, including an elemental and organic carbon (ECOC) type that proved to be the most suitable marker for meat smoking activities. The traditional activity of making preserved meat in southwestern China is shown here to be a major source of particulate pollution. Improved measures to reduce emissions from the smoking of meat should be introduced to improve air quality in regions where smoking meat activity prevails. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Superparamagnetism in carbon-coated Co particles produced by the Kratschmer carbon arc process

    NASA Astrophysics Data System (ADS)

    McHenry, M. E.; Majetich, S. A.; Artman, J. O.; Degraef, M.; Staley, S. W.

    1994-04-01

    A process based on the Kratschmer-Huffman carbon arc method of preparing fullerenes has been used to generate carbon-coated cobalt and cobalt carbide nanocrystallites. Magnetic nanocrystallites are extracted from the soot with a gradient field technique. For Co/C composites, structural characterization by x-ray diffraction and high-resolution transmission electron microscopy reveals the presence of a fcc Co phase, graphite, and a minority Co2C phase. The majority of Co nanocrystals exists as nominally spherical particles, 0.5-5 nm in radius. Hysteretic and temperature-dependent magnetic response, in randomly and magnetically aligned powder samples frozen in epoxy reveals fine-particle magnetism associated with monodomain Co particles. The magnetization exhibits a unique functional dependence on H/T, and hysteresis below a blocking temperature, TB~=160 K. Below TB, the temperature dependence of the coercivity is given by Hc=Hci[1-(T/TB)1/2], with Hci~=450 Oe.

  15. UV/TiO2 photocatalytic disinfection of carbon-bacteria complexes in activated carbon-filtered water: Laboratory and pilot-scale investigation.

    PubMed

    Zhao, Jin Hui; Chen, Wei; Zhao, Yaqian; Liu, Cuiyun; Liu, Ranbin

    2015-01-01

    The occurrence of carbon-bacteria complexes in activated carbon filtered water has posed a public health problem regarding the biological safety of drinking water. The application of combined process of ultraviolet radiation and nanostructure titanium dioxide (UV/TiO2) photocatalysis for the disinfection of carbon-bacteria complexes were assessed in this study. Results showed that a 1.07 Lg disinfection rate can be achieved using a UV dose of 20 mJ cm(-2), while the optimal UV intensity was 0.01 mW cm(-2). Particle sizes ≥8 μm decreased the disinfection efficiency, whereas variation in particle number in activated carbon-filtered water did not significantly affect the disinfection efficiency. Photoreactivation ratio was reduced from 12.07% to 1.69% when the UV dose was increased from 5 mJ cm(-2) to 20 mJ cm(-2). Laboratory and on-site pilot-scale experiments have demonstrated that UV/TiO2 photocatalytic disinfection technology is capable of controlling the risk posed by carbon-bacteria complexes and securing drinking water safety.

  16. Estimates of increased black carbon emissions from electrostatic precipitators during powdered activated carbon injection for mercury emissions control.

    PubMed

    Clack, Herek L

    2012-07-03

    The behavior of mercury sorbents within electrostatic precipitators (ESPs) is not well-understood, despite a decade or more of full-scale testing. Recent laboratory results suggest that powdered activated carbon exhibits somewhat different collection behavior than fly ash in an ESP and particulate filters located at the outlet of ESPs have shown evidence of powdered activated carbon penetration during full-scale tests of sorbent injection for mercury emissions control. The present analysis considers a range of assumed differential ESP collection efficiencies for powdered activated carbon as compared to fly ash. Estimated emission rates of submicrometer powdered activated carbon are compared to estimated emission rates of particulate carbon on submicrometer fly ash, each corresponding to its respective collection efficiency. To the extent that any emitted powdered activated carbon exhibits size and optical characteristics similar to black carbon, such emissions could effectively constitute an increase in black carbon emissions from coal-based stationary power generation. The results reveal that even for the low injection rates associated with chemically impregnated carbons, submicrometer particulate carbon emissions can easily double if the submicrometer fraction of the native fly ash has a low carbon content. Increasing sorbent injection rates, larger collection efficiency differentials as compared to fly ash, and decreasing sorbent particle size all lead to increases in the estimated submicrometer particulate carbon emissions.

  17. Chemical compositions of black carbon particle cores and coatings via soot particle aerosol mass spectrometry with photoionization and electron ionization.

    PubMed

    Canagaratna, Manjula R; Massoli, Paola; Browne, Eleanor C; Franklin, Jonathan P; Wilson, Kevin R; Onasch, Timothy B; Kirchstetter, Thomas W; Fortner, Edward C; Kolb, Charles E; Jayne, John T; Kroll, Jesse H; Worsnop, Douglas R

    2015-05-14

    Black carbon is an important constituent of atmospheric aerosol particle matter (PM) with significant effects on the global radiation budget and on human health. The soot particle aerosol mass spectrometer (SP-AMS) has been developed and deployed for real-time ambient measurements of refractory carbon particles. In the SP-AMS, black carbon or metallic particles are vaporized through absorption of 1064 nm light from a CW Nd:YAG laser. This scheme allows for continuous "soft" vaporization of both core and coating materials. The main focus of this work is to characterize the extent to which this vaporization scheme provides enhanced chemical composition information about aerosol particles. This information is difficult to extract from standard SP-AMS mass spectra because they are complicated by extensive fragmentation from the harsh 70 eV EI ionization scheme that is typically used in these instruments. Thus, in this work synchotron-generated vacuum ultraviolet (VUV) light in the 8-14 eV range is used to measure VUV-SP-AMS spectra with minimal fragmentation. VUV-SP-AMS spectra of commercially available carbon black, fullerene black, and laboratory generated flame soots were obtained. Small carbon cluster cations (C(+)-C5(+)) were found to dominate the VUV-SP-AMS spectra of all the samples, indicating that the corresponding neutral clusters are key products of the SP vaporization process. Intercomparisons of carbon cluster ratios observed in VUV-SP-AMS and SP-AMS spectra are used to confirm spectral features that could be used to distinguish between different types of refractory carbon particles. VUV-SP-AMS spectra of oxidized organic species adsorbed on absorbing cores are also examined and found to display less thermally induced decomposition and fragmentation than spectra obtained with thermal vaporization at 200 °C (the minimum temperature needed to quantitatively vaporize ambient oxidized organic aerosol with a continuously heated surface). The particle cores

  18. Protein encapsulation and release from PEO-b-polyphosphoester templated calcium carbonate particles.

    PubMed

    Ergul Yilmaz, Zeynep; Cordonnier, Thomas; Debuigne, Antoine; Calvignac, Brice; Jerome, Christine; Boury, Frank

    2016-11-20

    Calcium carbonate particles are promising candidates as proteins carriers for their controlled delivery in the body. The present paper aims at investigating the protein encapsulation by in situ precipitation of calcium carbonate particles prepared by a process based on supercritical CO 2 and using a new type of degradable well-defined double hydrophilic block copolymers composed of poly(ethylene oxide) and polyphosphoester blocks acting as templating agent for the calcium carbonate. For this study, lysozyme was chosen as a model for therapeutic protein for its availability and ease of detection. It was found that by this green process, loading into the CaCO 3 microparticles with a diameter about 2μm can be obtained as determined by scanning electron microscopy. A protein loading up to 6.5% active lysozyme was measured by a specific bioassay (Micrococcus lysodeikticus). By encapsulating fluorescent-labelled lysozyme (lysozyme-FITC), the confocal microscopy images confirmed its encapsulation and suggested a core-shell distribution of lysozyme into CaCO 3 , leading to a release profile reaching a steady state at 59% of release after 90min. Copyright © 2016. Published by Elsevier B.V.

  19. Stable Carbon Fractionation In Size Segregated Aerosol Particles Produced By Controlled Biomass Burning

    NASA Astrophysics Data System (ADS)

    Masalaite, Agne; Garbaras, Andrius; Garbariene, Inga; Ceburnis, Darius; Martuzevicius, Dainius; Puida, Egidijus; Kvietkus, Kestutis; Remeikis, Vidmantas

    2014-05-01

    Biomass burning is the largest source of primary fine fraction carbonaceous particles and the second largest source of trace gases in the global atmosphere with a strong effect not only on the regional scale but also in areas distant from the source . Many studies have often assumed no significant carbon isotope fractionation occurring between black carbon and the original vegetation during combustion. However, other studies suggested that stable carbon isotope ratios of char or BC may not reliably reflect carbon isotopic signatures of the source vegetation. Overall, the apparently conflicting results throughout the literature regarding the observed fractionation suggest that combustion conditions may be responsible for the observed effects. The purpose of the present study was to gather more quantitative information on carbonaceous aerosols produced in controlled biomass burning, thereby having a potential impact on interpreting ambient atmospheric observations. Seven different biomass fuel types were burned under controlled conditions to determine the effect of the biomass type on the emitted particulate matter mass and stable carbon isotope composition of bulk and size segregated particles. Size segregated aerosol particles were collected using the total suspended particle (TSP) sampler and a micro-orifice uniform deposit impactor (MOUDI). The results demonstrated that particle emissions were dominated by the submicron particles in all biomass types. However, significant differences in emissions of submicron particles and their dominant sizes were found between different biomass fuels. The largest negative fractionation was obtained for the wood pellet fuel type while the largest positive isotopic fractionation was observed during the buckwheat shells combustion. The carbon isotope composition of MOUDI samples compared very well with isotope composition of TSP samples indicating consistency of the results. The measurements of the stable carbon isotope ratio in

  20. ¹¹¹Indium-labeled ultrafine carbon particles; a novel aerosol for pulmonary deposition and retention studies.

    PubMed

    Sanchez-Crespo, Alejandro; Klepczynska-Nyström, Anna; Lundin, Anders; Larsson, Britt Marie; Svartengren, Magnus

    2011-02-01

    Continuous environmental or occupational exposure to airborne particulate pollution is believed to be a major hazard for human health. A technique to characterize their deposition and clearance from the lungs is fundamental to understand the underlying mechanisms behind their negative health effects. In this work, we describe a method for production and follow up of ultrafine carbon particles labeled with radioactive ¹¹¹Indium (¹¹¹In). The physicochemical and biological properties of the aerosol are described in terms of particle size and concentration, agglomeration rate, chemical bonding stability, and human lung deposition and retention. Preliminary in vivo data from a healthy human pilot exposure and 1-week follow up of the aerosol is presented. More than 98% of the generated aerosol was labeled with Indium and with particle sizes log normally distributed around 79  nm count median diameter. The aerosol showed good generation reproducibility and chemical stability, about 5% leaching 7 days after generation. During human inhalation, the particles were deposited in the alveolar space, with no central airways involvement. Seven days after exposure, the cumulative activity retention was 95.3%. Activity leaching tests from blood and urine samples confirmed that the observed clearance was explained by unbound activity, suggesting that there was no significant elimination of ultrafine particles. Compared to previously presented methods based on Technegas, ¹¹¹In-labelled ultrafine carbon particles allow for extended follow-up assessments of particulate pollution retention in healthy and diseased lungs.

  1. Entropy production of active particles and for particles in active baths

    NASA Astrophysics Data System (ADS)

    Pietzonka, Patrick; Seifert, Udo

    2018-01-01

    Entropy production of an active particle in an external potential is identified through a thermodynamically consistent minimal lattice model that includes the chemical reaction providing the propulsion and ordinary translational noise. In the continuum limit, a unique expression follows, comprising a direct contribution from the active process and an indirect contribution from ordinary diffusive motion. From the corresponding Langevin equation, this physical entropy production cannot be inferred through the conventional, yet here ambiguous, comparison of forward and time-reversed trajectories. Generalizations to several interacting active particles and passive particles in a bath of active ones are presented explicitly, further ones are briefly indicated.

  2. Influence of acid functionalization on the cardiopulmonary toxicity of carbon nanotubes and carbon black particles in mice

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Tong Haiyan; McGee, John K.; Saxena, Rajiv K.

    2009-09-15

    Engineered carbon nanotubes are being developed for a wide range of industrial and medical applications. Because of their unique properties, nanotubes can impose potentially toxic effects, particularly if they have been modified to express functionally reactive chemical groups on their surface. The present study was designed to evaluate whether acid functionalization (AF) enhanced the cardiopulmonary toxicity of single-walled carbon nanotubes (SWCNT) as well as control carbon black particles. Mice were exposed by oropharyngeal aspiration to 10 or 40 {mu}g of saline-suspended single-walled carbon nanotubes (SWCNTs), acid-functionalized SWCNTs (AF-SWCNTs), ultrafine carbon black (UFCB), AF-UFCB, or 2 {mu}g LPS. 24 hours later,more » pulmonary inflammatory responses and cardiac effects were assessed by bronchoalveolar lavage and isolated cardiac perfusion respectively, and compared to saline or LPS-instilled animals. Additional mice were assessed for histological changes in lung and heart. Instillation of 40 {mu}g of AF-SWCNTs, UFCB and AF-UFCB increased percentage of pulmonary neutrophils. No significant effects were observed at the lower particle concentration. Sporadic clumps of particles from each treatment group were observed in the small airways and interstitial areas of the lungs according to particle dose. Patches of cellular infiltration and edema in both the small airways and in the interstitium were also observed in the high dose group. Isolated perfused hearts from mice exposed to 40 {mu}g of AF-SWCNTs had significantly lower cardiac functional recovery, greater infarct size, and higher coronary flow rate than other particle-exposed animals and controls, and also exhibited signs of focal cardiac myofiber degeneration. No particles were detected in heart tissue under light microscopy. This study indicates that while acid functionalization increases the pulmonary toxicity of both UFCB and SWCNTs, this treatment caused cardiac effects only with the AF-carbon

  3. Input related microbial carbon dynamic of soil organic matter in particle size fractions

    NASA Astrophysics Data System (ADS)

    Gude, A.; Kandeler, E.; Gleixner, G.

    2012-04-01

    This paper investigated the flow of carbon into different groups of soil microorganisms isolated from different particle size fractions. Two agricultural sites of contrasting organic matter input were compared. Both soils had been submitted to vegetation change from C3 (Rye/Wheat) to C4 (Maize) plants, 25 and 45 years ago. Soil carbon was separated into one fast-degrading particulate organic matter fraction (POM) and one slow-degrading organo-mineral fraction (OMF). The structure of the soil microbial community were investigated using phospholipid fatty acids (PLFA), and turnover of single PLFAs was calculated from the changes in their 13C content. Soil enzyme activities involved in the degradation of carbohydrates was determined using fluorogenic MUF (methyl-umbelliferryl phosphate) substrates. We found that fresh organic matter input drives soil organic matter dynamic. Higher annual input of fresh organic matter resulted in a higher amount of fungal biomass in the POM-fraction and shorter mean residence times. Fungal activity therefore seems essential for the decomposition and incorporation of organic matter input into the soil. As a consequence, limited litter input changed especially the fungal community favouring arbuscular mycorrhizal fungi. Altogether, supply and availability of fresh plant carbon changed the distribution of microbial biomass, the microbial community structure and enzyme activities and resulted in different priming of soil organic matter. Most interestingly we found that only at low input the OMF fraction had significantly higher calculated MRT for Gram-positive and Gram-negative bacteria suggesting high recycling of soil carbon or the use of other carbon sources. But on average all microbial groups had nearly similar carbon uptake rates in all fractions and both soils, which contrasted the turnover times of bulk carbon. Hereby the microbial carbon turnover was always faster than the soil organic carbon turnover and higher carbon input

  4. Heat Transfer Enhancement of Metal Hydride Particle Bed for Heat Driven Type Refrigerator by Carbon Fiber

    NASA Astrophysics Data System (ADS)

    Bae, Sang-Chul; Tanae, Takayuki; Monde, Masanori; Katsuta, Masafumi

    A series of study has been performed on the metal hydride particle beds of Ti0.15Zr0.85Cr0.9Fe0.6Ni0.2Mn0.3Cu0.05 (MH-1, using for heat source), Ti0.73Zr0.27Cr1.2Fe0.3Ni0.1Mn0.4Cu0.05 (MH-2, using for cooling load) to measure the effective thermal conductivities. The effective thermal conductivities of activated and oxidized MH particle bed in helium have been examined. Experiment results show that pressure has great influence on effective thermal conductivity in low pressure range (<0.5 MPa). And that influence decreases rapidly with increase of gas pressure. The reason of pressure dependence at low pressure range is that the mean free path of gas becomes greater than effective thickness of gas film which is important to the heat transfer mechanism of particle bed. In order to enhance the poor thermal conductivity of metal hydride particle bed, carbon fiber mixing method has been used in this study. Three types, two insert methods and five mass percentages of carbon fiber have been examined and compared. The highest effective thermal conductivity of MH particle bed has been reached with Type B carbon fiber which has second higher thermal conductivity, and 2 weight percentage. This method has acquired 5-6 times higher thermal conductivity than pure metal hydride particle beds with quite low quantity of additives, only 2 mass% of carbon fiber. This is a good result comparing to other method which can reach higher effective thermal conductivity but needs much higher percentage of additives too.

  5. Catalytic Metal Free Production of Large Cage Structure Carbon Particles: A Candidate for Hydrogen Storage

    NASA Technical Reports Server (NTRS)

    Kimura, Yuki; Nuth, Joseph A., III; Ferguson, Frank T.

    2005-01-01

    We will demonstrate that carbon particles consisting of large cages can be produced without catalytic metal. The carbon particles were produced in CO gas as well as by introduction of 5% methane gas into the CO gas. The gas-produced carbon particles were able to absorb approximately 16.2 wt% of hydrogen. This value is 2.5 times higher than the 6.5 wt% goal for the vehicular hydrogen storage proposed by the Department of Energy in the USA. Therefore, we believe that this carbon particle is an excellent candidate for hydrogen storage for fuel cells.

  6. Characteristic of betel nuts activated carbon and its application to Jumputan wastewater treatment

    NASA Astrophysics Data System (ADS)

    Cundari, L.; Sari, K. F.; Anggraini, L.

    2018-04-01

    Wastewater from Jumputan production contains synthetic dye which is harmful to the environment. The contaminant can be reduced by adsorption process using activated carbon. The activated carbon was prepared from betel nuts with carbonization temperature of 500°C and 0.5 M HCl as an activator. Batch mode experiments were conducted to study the effect of various factors, such as the size particle of adsorbent, the dosage of adsorbent, and the contact time on Jumputan’s dye adsorption. The volume of treated solution was 200 mL. This solution agitated using a Jar Test at 150 rpm. The objectives of this work were to analyze the characteristic of the betel nuts, to analyze the characteristic of the activated carbon and to determine adsorbent’s ability to dye adsorption. Betel nuts compositions were analyzed with proximate analysis method. The adsorbents were carried out by SEM-EDS analysis. The dye adsorptions were analyzed with a portable spectrophotometer. The result shows betel nuts contains 60.86% carbohydrate, 32.56% water, 2.17% fat, 3.35% protein, and 1.06% ash. The major component of the activated carbon is carbon (C) of 86.27%, and the rest is Oxygen (9.18%) and Aurum (4.55%). The best condition is the adsorbent that has a particle size of 250 pm (60 mesh), the dosage of 20 grams, and the contact time of 15 minutes with dye removal of 76.4%.

  7. Finite Element Analysis of Particle Ionization within Carbon Nanotube Ion Micro Thruster

    DTIC Science & Technology

    2017-12-01

    NAVAL POSTGRADUATE SCHOOL MONTEREY, CALIFORNIA THESIS Approved for public release. Distribution is unlimited. FINITE ELEMENT ...AND DATES COVERED Master’s thesis 4. TITLE AND SUBTITLE FINITE ELEMENT ANALYSIS OF PARTICLE IONIZATION WITHIN CARBON NANOTUBE ION MICRO THRUSTER 5...simulation, carbon nanotube simulation, microsatellite, finite element analysis, electric field, particle tracing 15. NUMBER OF PAGES 55 16. PRICE

  8. Zero-valent iron particles embedded on the mesoporous silica-carbon for chromium (VI) removal from aqueous solution

    NASA Astrophysics Data System (ADS)

    Xiong, Kun; Gao, Yuan; Zhou, Lin; Zhang, Xianming

    2016-09-01

    Nanoscale zero-valent iron (nZVI) particles were embedded on the walls of mesoporous silica-carbon (MSC) under the conditions of high-temperature carbonization and reduction and used to remove chromium (VI) from aqueous solution. The structure and textural properties of nZVI-MSC were characterized by the powder X-ray diffraction, transmission electron microscopy and N2 adsorption and desorption. The results show that nZVI-MSC has highly ordered mesoporous structure and large surface area, indistinguishable with that of MSC. Compared with the support MSC and iron particles supported on the activated carbon (nZVI/AC), nZVI-MSC exhibited much higher Cr(VI) removal efficiency with about 98 %. The removal process obeys a pseudo first-order model. Such excellent performance of nZVI-MSC could be ascribed to the large surface and iron particles embedded on the walls of the MSC, forming an intimate contact with the MSC. It is proposed that this feature might create certain micro-electrode on the interface of iron particles and MSC, which prevented the formation of metal oxide on the surface and provided fresh Fe surface for Cr(VI) removal.

  9. INDOOR-OUTDOOR RELATIONSHIPS OF PARTICLES, PAH, AND BLACK CARBON IN AN OCCUPIED TOWNHOUSE

    EPA Science Inventory

    Real-time instrumentation for measuring particles, PAH, and black carbon (soot) has been operated since May of 1998 in an occupied 3-story town house in Reston, VA. Indoor and outdoor concentrations have been measured every five minutes for the particles and black carbon and ev...

  10. Removal of organic dyes using Cr-containing activated carbon prepared from leather waste.

    PubMed

    Oliveira, Luiz C A; Coura, Camila Van Zanten; Guimarães, Iara R; Gonçalves, Maraisa

    2011-09-15

    In this work, hydrogen peroxide decomposition and oxidation of organics in aqueous medium were studied in the presence of activated carbon prepared from wet blue leather waste. The wet blue leather waste, after controlled pyrolysis under CO(2) flow, was transformed into chromium-containing activated carbons. The carbon with Cr showed high microporous surface area (up to 889 m(2)g(-1)). Moreover, the obtained carbon was impregnated with nanoparticles of chromium oxide from the wet blue leather. The chromium oxide was nanodispersed on the activated carbon, and the particle size increased with the activation time. It is proposed that these chromium species on the carbon can activate H(2)O(2) to generate HO radicals, which can lead to two competitive reactions, i.e. the hydrogen peroxide decomposition or the oxidation of organics in water. In fact, in this work we observed that activated carbon obtained from leather waste presented high removal of methylene blue dye combining the adsorption and oxidation processes. Copyright © 2011 Elsevier B.V. All rights reserved.

  11. Adsorption and Pore of Physical-Chemical Activated Coconut Shell Charcoal Carbon

    NASA Astrophysics Data System (ADS)

    Budi, E.; Umiatin, U.; Nasbey, H.; Bintoro, R. A.; Wulandari, Fi; Erlina, E.

    2018-04-01

    The adsorption of activated carbon of coconut shell charcoal on heavy metals (Cu and Fe) of the wastewater and its relation with the carbon pore structure was investigated. The coconut shell was pyrolized in kiln at temperature about 75 - 150 °C for about 6 hours to produce charcoal and then shieved into milimeter sized granule particles. Chemical activation was done by immersing the charcoal into chemical solution of KOH, NaOH, HCl and H3PO4, with various concentration. The activation was followed by physical activation using horizontal furnace at 400°C for 1 hours in argon gas environment with flow rate of 200 kg/m3. The surface morphology of activated carbon were characterized by using Scanning Electron Microscopy (SEM). Wastewater was made by dissolving CuSO4.5H2O and FeSO4.7H2O into aquades. The metal adsorption was analized by using Atomic Absorption Spectroscopy (AAS). The result shows that in general, the increase of chemical concentration cause the increase of pore number of activated carbon due to an excessive chemical attack and lead the increase of adsorption. However it tend to decrease as further increasing in chemical activator concentration due to carbon collapsing. In general, the adsorption of Cu and Fe metal from wastewater by activated carbon increased as the activator concentration was increased.

  12. Activated carbon from biomass

    NASA Astrophysics Data System (ADS)

    Manocha, S.; Manocha, L. M.; Joshi, Parth; Patel, Bhavesh; Dangi, Gaurav; Verma, Narendra

    2013-06-01

    Activated carbon are unique and versatile adsorbents having extended surface area, micro porous structure, universal adsorption effect, high adsorption capacity and high degree of surface reactivity. Activated carbons are synthesized from variety of materials. Most commonly used on a commercial scale are cellulosic based precursors such as peat, coal, lignite wood and coconut shell. Variation occurs in precursors in terms of structure and carbon content. Coir having very low bulk density and porous structure is found to be one of the valuable raw materials for the production of highly porous activated carbon and other important factor is its high carbon content. Exploration of good low cost and non conventional adsorbent may contribute to the sustainability of the environment and offer promising benefits for the commercial purpose in future. Carbonization of biomass was carried out in a horizontal muffle furnace. Both carbonization and activation were performed in inert nitrogen atmosphere in one step to enhance the surface area and to develop interconnecting porosity. The types of biomass as well as the activation conditions determine the properties and the yield of activated carbon. Activated carbon produced from biomass is cost effective as it is easily available as a waste biomass. Activated carbon produced by combination of chemical and physical activation has higher surface area of 2442 m2/gm compared to that produced by physical activation (1365 m2/gm).

  13. Effect of bead milling on chemical and physical characteristics of activated carbons pulverized to superfine sizes.

    PubMed

    Partlan, Erin; Davis, Kathleen; Ren, Yiran; Apul, Onur Guven; Mefford, O Thompson; Karanfil, Tanju; Ladner, David A

    2016-02-01

    Superfine powdered activated carbon (S-PAC) is an adsorbent material with particle size between roughly 0.1-1 μm. This is about an order of magnitude smaller than conventional powdered activated carbon (PAC), typically 10-50 μm. S-PAC has been shown to outperform PAC for adsorption of various drinking water contaminants. However, variation in S-PAC production methods and limited material characterization in prior studies lead to questions of how S-PAC characteristics deviate from that of its parent PAC. In this study, a wet mill filled with 0.3-0.5 mm yttrium-stabilized zirconium oxide grinding beads was used to produce S-PAC from seven commercially available activated carbons of various source materials, including two coal types, coconut shell, and wood. Particle sizes were varied by changing the milling time, keeping mill power, batch volume, and recirculation rate constant. As expected, mean particle size decreased with longer milling. A lignite coal-based carbon had the smallest mean particle diameter at 169 nm, while the wood-based carbon had the largest at 440 nm. The wood and coconut-shell based carbons had the highest resistance to milling. Specific surface area and pore volume distributions were generally unchanged with increased milling time. Changes in the point of zero charge (pH(PZC)) and oxygen content of the milled carbons were found to correlate with an increasing specific external surface area. However, the isoelectric point (pH(IEP)), which measures only external surfaces, was unchanged with milling and also much lower in value than pH(PZC). It is likely that the outer surface is easily oxidized while internal surfaces remain largely unchanged, which results in a lower average pH as measured by pH(PZC). Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. Livestock air treatment using PVA-coated powdered activated carbon biofilter

    USDA-ARS?s Scientific Manuscript database

    The efficacy of polyvinyl alcohol (PVA) biofilters was studied using bench-scale biofilters and air from aerobically-treated swine manure. The PVA-coated powdered activated carbon particles showed excellent properties as a biofiltration medium: water holding capacity of 1.39 g H2O/g-dry PVA; wet por...

  15. Liquid Plasma Synthesis of Carbon Coated Iron Oxide Particles

    NASA Astrophysics Data System (ADS)

    Uygun, Aysegul; Hershkowitz, Noah; Eren, Esin; Uygun, Emre; Celik Cogal, Gamze; Yurdabak Karaca, Gozde; Manolache, Sorin; Sundaram, Gunasekaran; Sadak, Omer; Oksuz, Lutfi

    2017-10-01

    Recently, magnetic metal or metal oxide nanoparticles encapsulated in carbon are important in biomedical applications. The relevant reason to study toxicity of the magnetic nanoparticles coated by carbon is that they have great potential to contribute to cancer treatment. In this work, the synthesis of iron oxide nano-particles coated by graphitic carbon shells using pulsed plasma in liquid method. Short duration of RF plasma discharge, low electrical energy and fast quenching of the surrounding media can let to synthesize various kinds of pure nanoparticles. Corresponding author: ayseguluygun@sdu.edu.tr, lutfioksuz@sdu.edu.tr.

  16. Lung dendritic cells are stimulated by ultrafine particles and play a key role in particle adjuvant activity.

    PubMed

    de Haar, Colin; Kool, Mirjam; Hassing, Ine; Bol, Marianne; Lambrecht, Bart N; Pieters, Raymond

    2008-05-01

    The adjuvant activity of air pollution particles on allergic airway sensitization is well known, but the cellular mechanisms underlying this adjuvant potential are not clear. We sough to study the role of dendritic cells and the costimulatory molecules CD80 and CD86 in the adjuvant activity of ultrafine carbon black particles (CBP). The proliferation of CFSE-labeled DO11.10 CD4 cells was studied after intranasal exposure to particles and ovalbumin (OVA). Next the frequency of myeloid dendritic cells (mDCs) and plasmacytoid dendritic cells and their expression of CD80 and CD86 were studied in the peribronchial lymph nodes (PBLNs). The expression of costimulatory molecules was also studied on bone marrow-derived mDCs after exposure to CBPs in vitro, and the importance of costimulation in CBP adjuvant activity was assessed by using CD80/CD86-deficient mice or cytotoxic T lymphocyte-associated antigen 4 (CTLA4)-Ig in vivo. Our data show that CBPs plus OVA caused proliferation of DO11.10 CD4 cells and high levels of cytokine production in the PBLNs. Furthermore, the combined CBP plus OVA exposure increased the number of mDCs and expression of costimulatory molecules in the PBLNs. In addition, CBPs upregulated the expression of CD80/CD86 molecules on dendritic cells in vitro, which are necessary for the particle adjuvant effects in vivo. Together this study shows the importance of dendritic cells and costimulation in particle adjuvant activity. Furthermore, we show for the first time that CBPs can also directly induce maturation of dendritic cells.

  17. Assessment of exhaust emissions from carbon nanotube production and particle collection by sampling filters.

    PubMed

    Tsai, Candace Su-Jung; Hofmann, Mario; Hallock, Marilyn; Ellenbecker, Michael; Kong, Jing

    2015-11-01

    This study performed a workplace evaluation of emission control using available air sampling filters and characterized the emitted particles captured in filters. Characterized particles were contained in the exhaust gas released from carbon nanotube (CNT) synthesis using chemical vapor deposition (CVD). Emitted nanoparticles were collected on grids to be analyzed using transmission electron microscopy (TEM). CNT clusters in the exhaust gas were collected on filters for investigation. Three types of filters, including Nalgene surfactant-free cellulose acetate (SFCA), Pall A/E glass fiber, and Whatman QMA quartz filters, were evaluated as emission control measures, and particles deposited in the filters were characterized using scanning transmission electron microscopy (STEM) to further understand the nature of particles emitted from this CNT production. STEM analysis for collected particles on filters found that particles deposited on filter fibers had a similar morphology on all three filters, that is, hydrophobic agglomerates forming circular beaded clusters on hydrophilic filter fibers on the collecting side of the filter. CNT agglomerates were found trapped underneath the filter surface. The particle agglomerates consisted mostly of elemental carbon regardless of the shapes. Most particles were trapped in filters and no particles were found in the exhaust downstream from A/E and quartz filters, while a few nanometer-sized and submicrometer-sized individual particles and filament agglomerates were found downstream from the SFCA filter. The number concentration of particles with diameters from 5 nm to 20 µm was measured while collecting particles on grids at the exhaust piping. Total number concentration was reduced from an average of 88,500 to 700 particle/cm(3) for the lowest found for all filters used. Overall, the quartz filter showed the most consistent and highest particle reduction control, and exhaust particles containing nanotubes were successfully

  18. Ultrasonic Remove of Particle Aggregation in Carbon Based Counter Electrodes for Dye-Sensitized Solar Cells.

    PubMed

    Yang, Pan; Hu, Zi-Jun; Lin, Hong; Lai, Xin-Chun; Zhao, Xiao-Chong; Yang, Li-Jun

    2018-06-01

    Low-cost carbon materials (carbon black and graphite power) were applied as substitution of platinum (Pt) in counter electrodes (CEs) for dye-sensitized solar cells (DSSCs). Three fabrication methods, such as ball-milled, pulp-refined, and ultrasonic-crushed, were applied to remove the particle aggregation in the carbon pastes. Then the carbon based pastes were printed on fluorine-doped transparent conducting oxide (FTO) glasses, used as the CEs for DSSCs. Under illumination of 100 mW/cm2, DSSCs with ultrasonic-crushed CEs (U-CEs) show an energy conversion efficiency of 3.57%, which reach to 65.38% of that with conventional sputtered platinum CEs (5.46%). In addition, U-CEs exhibit a higher catalytic activity and a faster charge transfer rate toward the reduction of I-3 to I-.

  19. Single Atomic Iron Catalysts for Oxygen Reduction in Acidic Media: Particle Size Control and Thermal Activation

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zhang, Hanguang; Hwang, Sooyeon; Wang, Maoyu

    To significantly reduce the cost of proton exchange membrane (PEM) fuel cells, current Pt must be replaced by platinum-metal-group (PGM)-free catalysts for the oxygen reduction reaction (ORR) in acid. We report here a new class of high-performance atomic iron dispersed carbon catalysts through controlled chemical doping of iron ions into zinc-zeolitic imidazolate framework (ZIF), a type of metal-organic framework (MOF). The novel synthetic chemistry enables accurate size control of Fe-doped ZIF catalyst particles with a wide range from 20 to 1000 nm without changing chemical properties, which provides a great opportunity to increase the density of active sites that ismore » determined by the particle size. We elucidated the active site formation mechanism by correlating the chemical and structural changes with thermal activation process for the conversion from Fe-N4 complex containing hydrocarbon networks in ZIF to highly active FeNx sites embedded into carbon. A temperature of 800oC was identified as the critical point to start forming pyridinic nitrogen doping at the edge of the graphitized carbon planes. Further increasing heating temperature to 1100oC leads to increase of graphitic nitrogen, generating possible synergistic effect with FeNx sites to promote ORR activity. The best performing catalyst, which has well-defined particle size around 50 nm and abundance of atomic FeNx sites embedded into carbon structures, achieve a new performance milestone for the ORR in acid including a half-wave potential of 0.85 V vs RHE and only 20 mV loss after 10,000 cycles in O2 saturated H2SO4 electrolyte. The new class PGM-free catalyst with approaching activity to Pt holds great promise for future PEM fuel cells.« less

  20. Growth dynamics of carbon-metal particles and nanotubes synthesized by CO2 laser vaporization

    NASA Astrophysics Data System (ADS)

    Kokai, F.; Takahashi, K.; Yudasaka, M.; Iijima, S.

    To study the growth of carbon-Co/Ni particles and single-wall carbon nanotubes (SWNTs) by 20 ms CO2 laser-pulse irradiation of a graphite-Co/Ni (1.2 at.%) target in an Ar gas atmosphere (600 Torr), we used emission imaging spectroscopy and shadowgraphy with a temporal resolution of 1.67 ms. Wavelength-selected emission images showed that C2 emission was strong in the region close to the target (within 2 cm), while for the same region the blackbody radiation from the large clusters or particles increased with increasing distance from the target. Shadowgraph images showed that the viscous flow of carbon and metal species formed a mushroom or a turbulent cloud spreading slowly into the Ar atmosphere, indicating that particles and SWNTs continued to grow as the ejected material cooled. In addition, emission imaging spectroscopy at 1200 °C showed that C2 and hot clusters and particles with higher emission intensities were distributed over much wider areas. We discuss the growth dynamics of the particles and SWNTs through the interaction of the ambient Ar with the carbon and metal species released from the target by the laser pulse.

  1. Equilibrium and kinetics of adsorption of phosphate onto iron-doped activated carbon.

    PubMed

    Wang, Zhengfang; Nie, Er; Li, Jihua; Yang, Mo; Zhao, Yongjun; Luo, Xingzhang; Zheng, Zheng

    2011-08-01

    Two series of activated carbons modified by Fe (II) and Fe (III) (denoted as AC/N-Fe(II) and AC/N-Fe(III)), respectively, were used as adsorbents for the removal of phosphate in aqueous solutions. The synthesized adsorbent materials were investigated by different experimental analysis means. The adsorption of phosphate on activated carbons has been studied in kinetic and equilibrium conditions taking into account the adsorbate concentration, temperature, and solution pH as major influential factors. Maximum removals of phosphate are obtained in the pH range of 3.78-6.84 for both adsorbents. Langmuir isotherm adsorption equation well describes the experimental adsorption isotherms. Kinetic studies revealed that the adsorption process followed a pseudo-second order kinetic model. Results suggest that the main phase formed in AC/N-Fe(II) and AC/N-Fe(III) is goethite and akaganeite, respectively; the presence of iron oxides significantly affected the surface area and the pore structure of the activated carbon. Studies revealed that iron-doped activated carbons were effective in removing phosphate. AC/N-Fe(II) has a higher phosphate removal capacity than AC/N-Fe(III), which could be attributed to its better intra-particle diffusion and higher binding energy. The activation energy for adsorption was calculated to be 22.23 and 10.89 kJ mol(-1) for AC/N-Fe(II) and AC/N-Fe(III), respectively. The adsorption process was complex; both surface adsorption and intra-particle diffusion were simultaneously occurring during the process and contribute to the adsorption mechanism.

  2. Online single particle measurements of black carbon coatings, structure and optical properties

    NASA Astrophysics Data System (ADS)

    Allan, James; Liu, Dantong; Taylor, Jonathan; Flynn, Michael; Williams, Paul; Morgan, William; Whitehead, James; Alfarra, Rami; McFiggans, Gordon; Coe, Hugh

    2016-04-01

    The impacts of black carbon on meteorology and climate remain a major source of uncertainty, owing in part to the complex relationship between the bulk composition of the particulates and their optical properties. A particular complication stems from how light interacts with particles in response to the microphysical configuration and any 'coatings', i.e. non-black carbon material that is either co-emitted or subsequently obtained through atmospheric processing. This may cause the particle to more efficiently absorb or scatter light and may even change the sign of its radiative forcing potential. While much insight has been gained through measurements of bulk aerosol properties, either while suspended or after collection on a filter or impactor substrate, this does not provide a complete picture and thus may not adequately constrain the system. Here we present an overview of recent work to better constrain the properties of black carbon using online, in situ measurements of single particles, primarily using a Single Particle Soot Photometer (SP2). We have developed novel methods of inverting the data produced and combining the different metrics derived so as to give the most effective insights into black carbon sources, processes and properties. We have also used this measurement in conjunction with other instruments (sometimes in series) and used the data to challenge many commonly used models of optical properties such as core-shell Mie, Rayleigh-Debeye-Gans and effective medium. This work has been carried out in a variety of atmospheric environments and with laboratory-produced soots, e.g. from a diesel engine rig. Highlights include the finding that with real-world atmospheric aerosols, bulk optical measurements may be insufficient to derive brown carbon parameters without detailed morphological data. We also show that the enhancement of absorption for both ambient and laboratory generated particles only occurs after the coating mass fraction reaches a certain

  3. Silver Nanoparticle Impregnated Bio-Based Activated Carbon with Enhanced Antimicrobial Activity

    NASA Astrophysics Data System (ADS)

    Selvakumar, R.; Suriyaraj, S. P.; Jayavignesh, V.; Swaminathan, K.

    2013-08-01

    The present study involves the production of silver nanoparticles using a novel yeast strain Saccharomyces cerevisiae BU-MBT CY-1 isolated from coconut cell sap. The biological reduction of silver nitrate by the isolate was deducted at various time intervals. The yeast cells after biological silver reduction were harvested and subjected to carbonization at 400°C for 1 h and its properties were analyzed using Fourier transform infra-red spectroscopy, X-ray diffraction, scanning electron microscope attached with energy dispersive spectroscopy and transmission electron microscopy. The average size of the silver nanoparticles present on the surface of the carbonized silver containing yeast cells (CSY) was 19 ± 9 nm. The carbonized control yeast cells (CCY) did not contain any particles on its surface. The carbonized silver nanoparticles containing yeast cells (CSY) were made into bioactive emulsion and tested for its efficacy against various pathogenic Gram positive and Gram negative bacteria. The antimicrobial activity studies indicated that CSY bioactive nanoemulsion was effective against Gram negative organisms than Gram positive organism.

  4. Nanocarpets for Trapping Microscopic Particles

    NASA Technical Reports Server (NTRS)

    Noca, Flavio; Chen, Fei; Hunt, Brian; Bronikowski, Michael; Hoenk, Michael; Kowalczyk, Robert; Choi, Daniel

    2004-01-01

    Nanocarpets that is, carpets of carbon nanotubes are undergoing development as means of trapping microscopic particles for scientific analysis. Examples of such particles include inorganic particles, pollen, bacteria, and spores. Nanocarpets can be characterized as scaled-down versions of ordinary macroscopic floor carpets, which trap dust and other particulate matter, albeit not purposefully. Nanocarpets can also be characterized as mimicking both the structure and the particle-trapping behavior of ciliated lung epithelia, the carbon nanotubes being analogous to cilia. Carbon nanotubes can easily be chemically functionalized for selective trapping of specific particles of interest. One could, alternatively, use such other three-dimensionally-structured materials as aerogels and activated carbon for the purposeful trapping of microscopic particles. However, nanocarpets offer important advantages over these alternative materials: (1) Nanocarpets are amenable to nonintrusive probing by optical means; and (2) Nanocarpets offer greater surface-to-volume ratios.

  5. Activated, coal-based carbon foam

    DOEpatents

    Rogers, Darren Kenneth; Plucinski, Janusz Wladyslaw

    2004-12-21

    An ablation resistant, monolithic, activated, carbon foam produced by the activation of a coal-based carbon foam through the action of carbon dioxide, ozone or some similar oxidative agent that pits and/or partially oxidizes the carbon foam skeleton, thereby significantly increasing its overall surface area and concurrently increasing its filtering ability. Such activated carbon foams are suitable for application in virtually all areas where particulate or gel form activated carbon materials have been used. Such an activated carbon foam can be fabricated, i.e. sawed, machined and otherwise shaped to fit virtually any required filtering location by simple insertion and without the need for handling the "dirty" and friable particulate activated carbon foam materials of the prior art.

  6. Adsorption of Safranin-T from wastewater using waste materials- activated carbon and activated rice husks.

    PubMed

    Gupta, Vinod K; Mittal, Alok; Jain, Rajeev; Mathur, Megha; Sikarwar, Shalini

    2006-11-01

    Textile effluents are major industrial polluters because of high color content, about 15% unfixed dyes and salts. The present paper is aimed to investigate and develop cheap adsorption methods for color removal from wastewater using waste materials activated carbon and activated rice husk-as adsorbents. The method was employed for the removal of Safranin-T and the influence of various factors such as adsorbent dose, adsorbate concentration, particle size, temperature, contact time, and pH was studied. The adsorption of the dye over both the adsorbents was found to follow Langmuir and Freundlich adsorption isotherm models. Based on these models, different useful thermodynamic parameters have been evaluated for both the adsorption processes. The adsorption of Safranin-T over activated carbon and activated rice husks follows first-order kinetics and the rate constants for the adsorption processes decrease with increase in temperature.

  7. Characterization of airborne particles generated from metal active gas welding process.

    PubMed

    Guerreiro, C; Gomes, J F; Carvalho, P; Santos, T J G; Miranda, R M; Albuquerque, P

    2014-05-01

    This study is focused on the characterization of particles emitted in the metal active gas welding of carbon steel using mixture of Ar + CO2, and intends to analyze which are the main process parameters that influence the emission itself. It was found that the amount of emitted particles (measured by particle number and alveolar deposited surface area) are clearly dependent on the distance to the welding front and also on the main welding parameters, namely the current intensity and heat input in the welding process. The emission of airborne fine particles seems to increase with the current intensity as fume-formation rate does. When comparing the tested gas mixtures, higher emissions are observed for more oxidant mixtures, that is, mixtures with higher CO2 content, which result in higher arc stability. These mixtures originate higher concentrations of fine particles (as measured by number of particles by cm(3) of air) and higher values of alveolar deposited surface area of particles, thus resulting in a more severe worker's exposure.

  8. Use of manganese oxide and activated carbon fibers for removing a particle, volatile organic compound or ozone from a gas

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sidheswaran, Meera A.; Destaillats, Hugo; Fisk, William J.

    The present invention provides for a device for reducing a volatile organic compound (VOC) content of a gas comprising a manganese oxide (MnO.sub.x) catalyst. The manganese oxide (MnO.sub.x) catalyst is capable of catalyzing formaldehyde at room temperature, with complete conversion, to CO.sub.2 and water vapor. The manganese oxide (MnO.sub.x) catalyst itself is not consumed by the reaction of formaldehyde into CO.sub.2 and water vapor. The present invention also provides for a device for reducing or removing a particle, a VOC and/or ozone from a gas comprising an activated carbon filter (ACF) on a media that is capable of being periodicallymore » regenerated.« less

  9. Geochemical and petrographical characterization of fine-grained carbonate particles along proximal to distal transects

    NASA Astrophysics Data System (ADS)

    Turpin, Mélanie; Emmanuel, Laurent; Immenhauser, Adrian; Renard, Maurice

    2012-12-01

    The origin of carbonate ooze particles is often poorly understood. This is due to their polygenic origin and potential post-depositional alteration. Here, the outcome of a physical separation study with regard to different component classes of micritic carbonates is shown. The focus is on grain size and morphology, mineralogy and isotope signatures. Two contrasting proximal-to-distal transects were investigated: (1) the Miocene leeward margin of Great Bahama Bank (ODP Leg 166) and (2) the transition between the Maiella platform and the Umbria-Marche basin in central Italy near the Cenomanian-Turonian boundary. In both case settings, carbonate particles of biogenic origin include at least three groups of organisms: (i) planktonic foraminifera, (ii) calcareous nannofossils and (iii) fragments of unspecified neritic skeletal material. Two further particle types lack diagnostic structures, and based on particle size and mineralogy, are here referred to as (iv) macroparticles (5-20 μm, mainly xenomorphic) and (v) microparticles (< 12 μm, mainly automorphic to sub-automorphic). Macro- and microparticles represent 50 to 80% of the carbonate phase in slope and toe-of-slope domains and share characteristic carbon and oxygen isotope signatures. Macro- and microparticles are considered shallow-water precipitation products subsequently exported into the slope and toe-of-slope domains. Macroparticles are probably related to the fragmentation of neritic skeletal components while microparticles point to inorganic and/or bioinduced precipitation in the water column. In some cases, macro- and microparticles may have an early diagenetic origin. The identification of the origin of fine-grained particles allows for a quantitative assessment of exported, in situ and diagenetic carbonate materials in periplatform environments. The data shown here represent an important step towards a more complete characterization of carbonate ooze and micrite.

  10. [Characteristics of soil organic carbon and enzyme activities in soil aggregates under different vegetation zones on the Loess Plateau].

    PubMed

    Li, Xin; Ma, Rui-ping; An, Shao-shan; Zeng, Quan-chao; Li, Ya-yun

    2015-08-01

    In order to explore the distribution characteristics of organic carbon of different forms and the active enzymes in soil aggregates with different particle sizes, soil samples were chosen from forest zone, forest-grass zone and grass zone in the Yanhe watershed of Loess Plateau to study the content of organic carbon, easily oxidized carbon, and humus carbon, and the activities of cellulase, β-D-glucosidase, sucrose, urease and peroxidase, as well as the relations between the soil aggregates carbon and its components with the active soil enzymes were also analyzed. It was showed that the content of organic carbon and its components were in order of forest zone > grass zone > forest-grass zone, and the contents of three forms of organic carbon were the highest in the diameter group of 0.25-2 mm. The content of organic carbon and its components, as well as the activities of soil enzymes were higher in the soil layer of 0-10 cm than those in the 10-20 cm soil layer of different vegetation zones. The activities of cellulase, β-D-glucosidase, sucrose and urease were in order of forest zone > grass zone > forest-grass zone. The peroxidase activity was in order of forest zone > forest-grass zone > grass zone. The activities of various soil enzymes increased with the decreasing soil particle diameter in the three vegetation zones. The activities of cellulose, peroxidase, sucrose and urease had significant positive correlations with the contents of various forms of organic carbon in the soil aggregates.

  11. Black carbon, mass and elemental measurements of airborne particles in the village of Serowe, Botswana

    NASA Astrophysics Data System (ADS)

    Moloi, K.; Chimidza, S.; Lindgren, E. Selin; Viksna, A.; Standzenieks, P.

    Absorption of sunlight by sub-micron particles is an important factor in calculations of the radiation balance of the earth and thus in climate modelling. Carbon-containing particles are generally considered as the most important in this respect. Major sources of these particles are generally considered to be bio-mass burning and vehicle exhaust. In order to characterise size fractionated particulate matter in a rural village in Botswana with respect to light absorption and elemental content experiments were performed, in which simultaneous sampling was made with a dichotomous impactor and a laboratory-made sampler, made compatible with black carbon analysis by reflectometry. The dichotomous impactor was equipped with Teflon filters and the other sampler with glass fibre filters. Energy dispersive X-ray fluorescence was used for elemental analysis of both kinds of filters. It appeared that Teflon filters were the most suitable for the combination of mass-, elemental- and black carbon measurements. The black carbon content in coarse (2.5-10 μm) and fine (<2.5 μm) particles was determined separately and related to elemental content and emission source. The results show that the fine particle fraction in the aerosol has a much higher contribution of black particles than the coarse particle fraction. This observation is valid for the village in Botswana as well as for a typical industrialised city in Sweden, used as a reference location.

  12. Behaviors and kinetics of toluene adsorption-desorption on activated carbons with varying pore structure.

    PubMed

    Yang, Xi; Yi, Honghong; Tang, Xiaolong; Zhao, Shunzheng; Yang, Zhongyu; Ma, Yueqiang; Feng, Tiecheng; Cui, Xiaoxu

    2018-05-01

    This work was undertaken to investigate the behaviors and kinetics of toluene adsorption and desorption on activated carbons with varying pore structure. Five kinds of activated carbon from different raw materials were selected. Adsorption isotherms and breakthrough curves for toluene were measured. Langmuir and Freundlich equations were fitted to the equilibrium data, and the Freundlich equation was more suitable for simulating toluene adsorption. The process consisted of monolayer, multilayer and partial active site adsorption types. The effect of the pore structure of the activated carbons on toluene adsorption capacity was investigated. The quasi-first-order model was more suitable for describing the process than the quasi-second-order model. The adsorption data was also modeled by the internal particle diffusion model and it was found that the adsorption process could be divided into three stages. In the external surface adsorption process, the rate depended on the specific surface area. During the particle diffusion stage, pore structure and volume were the main factors affecting adsorption rate. In the final equilibrium stage, the rate was determined by the ratio of meso- and macro-pores to total pore volume. The rate over the whole adsorption process was dominated by the toluene concentration. The desorption behavior of toluene on activated carbons was investigated, and the process was divided into heat and mass transfer parts corresponding to emission and diffusion mechanisms, respectively. Physical adsorption played the main role during the adsorption process. Copyright © 2017. Published by Elsevier B.V.

  13. Method of evaluating the integrity of the outer carbon layer of triso-coated reactor fuel particles

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Caputo, A.J.; Costanzo, D.A.; Lackey, W.J.

    1980-10-07

    This invention relates to a method for determining defective final layers of carbon on triso-coated fuel particles and the like. Samples of the particles are subjected to a high temperature treatment with gaseous chlorine and thereafter radiographed. The chlorine penetrates through any defective carbon layer and reacts with the underlying silicon carbide resulting in the volatilization of the silicon as sicl4 leaving carbon as a porous layer. This porous carbon layer is easily detected by the radiography.

  14. A Carbon Source Apportionment Shift in Mexico City Atmospheric Particles During 2003-2004 as Determined with Stable Carbon Isotopes

    NASA Astrophysics Data System (ADS)

    Lopez-Veneroni, D. G.; Vega, E.

    2013-05-01

    The stable carbon isotope composition of atmospheric particles (PM2.5) was measured at La Merced (MER), a commercial site in the eastern sector, and at Xalostoc (XAL) an industrial site in the NE sector of Mexico City, during three sampling periods in autumn 2003, and spring and autumn 2004. At each site and sampling campaign particle samples were collected daily with minivol samplers during two week periods. Ancillary data included organic and elemental carbon, trace elements and ionic species. This data base was complement with air quality data from the RAMA (Automatic Atmospheric Monitoring Network). In general, particle concentrations, ionic species and some air quality species showed higher concentrations in autumn and lowest values in spring. Moreover, the concentrations of these chemical species were highest at XAL compared to MER. The stable carbon isotope composition of PM2.5 during autumn 2003 and spring 2004 had and average value of -26.04 (± 1.54) ‰ vs. PDB. Differences in the isotopic composition between the two sites were non significant. The average δ13C during these seasons were 1 ‰ lighter relative to data collected previously at these sites during 2000 and 2001, and is consistent with a predominant source of hydrocarbon combustion. In autumn 2004, however, average δ13C at XAL and MER increased to -22.8 (± 0.9) and -20.6 (± 3.1) ‰, respectively. Organic carbon concentrations during this period increased concomitantly at these sites. The shift in the isotopic composition in ambient particles suggests a predominance of soil-derived carbon during this period. The possible causes and implications of this are discussed.

  15. Preparation of a new adsorbent from activated carbon and carbon nanofiber (AC/CNF) for manufacturing organic-vacbpour respirator cartridge

    PubMed Central

    2013-01-01

    In this study a composite of activated carbon and carbon nanofiber (AC/CNF) was prepared to improve the performance of activated carbon (AC) for adsorption of volatile organic compounds (VOCs) and its utilization for respirator cartridges. Activated carbon was impregnated with a nickel nitrate catalyst precursor and carbon nanofibers (CNF) were deposited directly on the AC surface using catalytic chemical vapor deposition. Deposited CNFs on catalyst particles in AC micropores, were activated by CO2 to recover the surface area and micropores. Surface and textural characterizations of the prepared composites were investigated using Brunauer, Emmett and Teller’s (BET) technique and electron microscopy respectively. Prepared composite adsorbent was tested for benzene, toluene and xylene (BTX) adsorption and then employed in an organic respirator cartridge in granular form. Adsorption studies were conducted by passing air samples through the adsorbents in a glass column at an adjustable flow rate. Finally, any adsorbed species not retained by the adsorbents in the column were trapped in a charcoal sorbent tube and analyzed by gas chromatography. CNFs with a very thin diameter of about 10-20 nm were formed uniformly on the AC/CNF. The breakthrough time for cartridges prepared with CO2 activated AC/CNF was 117 minutes which are significantly longer than for those cartridges prepared with walnut shell- based activated carbon with the same weight of adsorbents. This study showed that a granular form CO2 activated AC/CNF composite could be a very effective alternate adsorbent for respirator cartridges due to its larger adsorption capacities and lower weight. PMID:23369424

  16. Selective Aliphatic Carbon-Carbon Bond Activation by Rhodium Porphyrin Complexes.

    PubMed

    To, Ching Tat; Chan, Kin Shing

    2017-07-18

    The carbon-carbon bond activation of organic molecules with transition metal complexes is an attractive transformation. These reactions form transition metal-carbon bonded intermediates, which contribute to fundamental understanding in organometallic chemistry. Alternatively, the metal-carbon bond in these intermediates can be further functionalized to construct new carbon-(hetero)atom bonds. This methodology promotes the concept that the carbon-carbon bond acts as a functional group, although carbon-carbon bonds are kinetically inert. In the past few decades, numerous efforts have been made to overcome the chemo-, regio- and, more recently, stereoselectivity obstacles. The synthetic usefulness of the selective carbon-carbon bond activation has been significantly expanded and is becoming increasingly practical: this technique covers a wide range of substrate scopes and transition metals. In the past 16 years, our laboratory has shown that rhodium porphyrin complexes effectively mediate the intermolecular stoichiometric and catalytic activation of both strained and nonstrained aliphatic carbon-carbon bonds. Rhodium(II) porphyrin metalloradicals readily activate the aliphatic carbon(sp 3 )-carbon(sp 3 ) bond in TEMPO ((2,2,6,6-tetramethylpiperidin-1-yl)oxyl) and its derivatives, nitriles, nonenolizable ketones, esters, and amides to produce rhodium(III) porphyrin alkyls. Recently, the cleavage of carbon-carbon σ-bonds in unfunctionalized and noncoordinating hydrocarbons with rhodium(II) porphyrin metalloradicals has been developed. The absence of carbon-hydrogen bond activation in these systems makes the reaction unique. Furthermore, rhodium(III) porphyrin hydroxide complexes can be generated in situ to selectively activate the carbon(α)-carbon(β) bond in ethers and the carbon(CO)-carbon(α) bond in ketones under mild conditions. The addition of PPh 3 promotes the reaction rate and yield of the carbon-carbon bond activation product. Thus, both rhodium

  17. Method of evaluating the integrity of the outer carbon layer of triso-coated reactor fuel particles

    DOEpatents

    Caputo, Anthony J.; Costanzo, Dante A.; Lackey, Jr., Walter J.; Layton, Frank L.; Stinton, David P.

    1980-01-01

    This invention relates to a method for determining defective final layers of carbon on triso-coated fuel particles and the like. Samples of the particles are subjected to a high temperature treatment with gaseous chlorine and thereafter radiographed. The chlorine penetrates through any defective carbon layer and reacts with the underlying silicon carbide resulting in the volatilization of the silicon as SiCl.sub.4 leaving carbon as a porous layer. This porous carbon layer is easily detected by the radiography.

  18. Microporous polystyrene particles for selective carbon dioxide capture.

    PubMed

    Kaliva, Maria; Armatas, Gerasimos S; Vamvakaki, Maria

    2012-02-07

    This study presents the synthesis of microporous polystyrene particles and the potential use of these materials in CO(2) capture for biogas purification. Highly cross-linked polystyrene particles are synthesized by the emulsion copolymerization of styrene (St) and divinylbenzene (DVB) in water. The cross-link density of the polymer is varied by altering the St/DVB molar ratio. The size and the morphology of the particles are characterized by scanning and transmission electron microscopy. Following supercritical point drying with carbon dioxide or lyophilization from benzene, the polystyrene nanoparticles exhibit a significant surface area and permanent microporosity. The dried particles comprising 35 mol % St and 65 mol % DVB possess the largest surface area, ∼205 m(2)/g measured by Brunauer-Emmett-Teller and ∼185 m(2)/g measured by the Dubinin-Radushkevich method, and a total pore volume of 1.10 cm(3)/g. Low pressure measurements suggest that the microporous polystyrene particles exhibit a good separation performance of CO(2) over CH(4), with separation factors in the range of ∼7-13 (268 K, CO(2)/CH(4) = 5/95 gas mixture), which renders them attractive candidates for use in gas separation processes.

  19. Heterogeneous fenton catalysts based on activated carbon and related materials.

    PubMed

    Navalon, Sergio; Dhakshinamoorthy, Amarajothi; Alvaro, Mercedes; Garcia, Hermenegildo

    2011-12-16

    The Fenton reaction is widely used for remediation of waste water and for the degradation of organic pollutants in water. Currently, there is considerable interest to convert the classical Fenton reaction, which consumes stoichiometric amounts of iron(II) salts, into a catalytic process that is promoted by a solid. This review describes the work that has used carbonaceous materials either directly as catalysts or, more frequently, as a large-area support for catalytically activated transition metals or metal-oxide nanoparticles. The interest in this type of catalyst derives from the wide use of carbon in conventional water treatments and the wide applicability of the Fenton reaction. After two general sections that illustrate the scope and background of Fenton chemistry, the review describes the activity of activated carbon in the absence or presence of metal-containing particles. The last sections of the review focus on different types of carbonaceous materials, such as carbon nanotubes and diamond nanoparticles. The review concludes with a section that anticipates future developments in this area, which are aimed at overcoming the current limitations of low activity and occurrence of metal leaching. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. The IR emission features - Emission from PAH molecules and amorphous carbon particles

    NASA Technical Reports Server (NTRS)

    Allamandola, L. J.; Tielens, A. G. G. M.; Barker, J. R.

    1987-01-01

    Techniques for the assessment of the importance of the various forms of PAHs, and recent infrared observations concerning the PAH problem, are considered. Spectroscopic data suggest that the observed interstellar spectrum is due to both free molecule-sized PAHs producing the narrow features, and amorphous carbon particles contributing to the broad underlying components. Explanations for the multicomponent emission spectrum are discussed. A model of the emission mechanism for the example of chrysene is presented, and an exact treatment of the IR fluorescence from highly vibrationally excited large molecules shows that species containing 20-30 carbon atoms are responsible for the narrow features, although the spectra more closely resemble those of amorphous carbon particles. It is suggested that future emphasis should be placed on the spatial characteristics of the component spectra.

  1. The IR emission features - Emission from PAH molecules and amorphous carbon particles

    NASA Technical Reports Server (NTRS)

    Allamandola, L. J.; Tielens, A. G. G. M.; Barker, J. R.

    1987-01-01

    Given the current understanding of polycyclic aromatic hydrocarbons (PAHs), the spectroscopic data suggest that are at least two components which contribute to the interstellar emission spectrum: (1) free molecule-sized PAHs producing the narrow features and (2) amorphous carbon particles (which are primarily composed of an irregular 'lattice' of PAHs) contributing to the broad underlying components. An exact treatment of the IR fluorescence from highly vibrationally excited large molecules demonstrates that species containing between 20 and 30 carbon atoms are responsible for the narrow features, although the spectra match more closely with the spectra of amorphous carbon particles. It is concluded that, since little is known about the spectroscopic properties of free PAHs and PAH clusters, much laboratory work is required along with an observational program focusing on the spatial characteristics of the spectra.

  2. [Carbon sequestration in soil particle-sized fractions during reversion of desertification at Mu Us Sand land.

    PubMed

    Ma, Jian Ye; Tong, Xiao Gang; Li, Zhan Bin; Fu, Guang Jun; Li, Jiao; Hasier

    2016-11-18

    The aim of this study was to investigate the effects of carbon sequestration in soil particle-sized fractions during reversion of desertification at Mu Us Sand Land, soil samples were collected from quicksand land, semifixed sand and fixed sand lands that were established by the shrub for 20-55 year-old and the arbor for 20-50 year-old at sand control region of Yulin in Northern Shaanxi Province. The dynamics and sequestration rate of soil organic carbon (SOC) associated with sand, silt and clay were measured by physical fractionation method. The results indicated that, compared with quicksand area, the carbon content in total SOC and all soil particle-sized fractions at bothsand-fixing sand forest lands showed a significant increasing trend, and the maximum carbon content was observed in the top layer of soils. From quicksand to fixed sand land with 55-year-old shrub and 50-year-old arbor, the annual sequestration rate of carbon stock in 0-5 cm soil depth was same in silt by 0.05 Mg·hm -2 ·a -1 . The increase rate of carbon sequestration in sand was 0.05 and 0.08 Mg·hm -2 ·a -1 , and in clay was 0.02 and 0.03 Mg·hm -2 ·a -1 at shrubs and arbors land, respectively. The increase rate of carbon sequestration in 0-20 cm soil layer for all the soil particles was averagely 2.1 times as that of 0-5 cm. At the annual increase rate of carbon, the stock of carbon in sand, silt and clay at the two fixed sand lands were increased by 6.7, 18.1 and 4.4 times after 50-55 year-old reversion of quicksand land to fixed sand. In addition, the average percentages that contributed to accumulation of total SOC by different particles in 0-20 cm soil were in the order of silt carbon (39.7%)≈sand carbon (34.6%) > clay carbon (25.6%). Generally, the soil particle-sized fractions had great carbon sequestration potential during reversion of desertification in Mu Us Sand Land, and the slit and sand were the main fractions for carbon sequestration at both fixed sand lands.

  3. Adsorption of lignite-derived humic acids on coal-based mesoporous activated carbons.

    PubMed

    Lorenc-Grabowska, Ewa; Gryglewicz, Grazyna

    2005-04-15

    The adsorption by a coal-based mesoporous activated carbon of humic acids (HAs) isolated from two Polish lignites was studied. For comparison, a commercial Aldrich humic acid was also included into this study. The differences in chemical structure and functional groups of HAs were determined by elemental analysis and infrared spectroscopy DRIFT. Two activated carbons used differed in terms of mesopore volume, mesopore size distribution, and chemical properties of the surface. The kinetics of adsorption of HAs have been discussed using three kinetic models, i.e., the first-order Lagergren model, the pseudo-second-order model, and the intraparticle diffusion model. It was found that the adsorption of HAs from alkaline solution on mesoporous activated carbon proceeds according to the pseudo-second-order model. The correlation coefficients were close to 1. The intraparticle diffusion of HA molecules within the carbon particle was identified to be the rate-limiting step. Comparing the two activated carbons, the carbon with a higher volume of pores with widths of 10-50 nm showed a greater removal efficiency of HA. An increase in the Freundlich adsorption capacity with decreasing carbon content of HA was observed. Among the HAs studied, S-HA shows characteristics indicating the highest contribution of small-size fraction. The S-HA was removed by both activated carbons to the highest extent. The effect of pH solution on the adsorption of HA was examined over the range pH 5.4-12.2. It was found that the extent of adsorption decreased with decreasing pH of the solution.

  4. [Effects of land use type on the distribution of organic carbon in different sized soil particles effects of land use type on the distribution of organic carbon in different sized soil particles and its relationships to herb biomass in hilly red soil region of South China].

    PubMed

    Li, Zhong-Wu; Guo, Wang; Wang, Xiao-Yan; Shen, Wei-Ping; Zhang, Xue; Chen, Xiao-Lin; Zhang, Yue-Nan

    2012-04-01

    The changes in organic carbon content in different sized soil particles under different land use patterns partly reflect the variation of soil carbon, being of significance in revealing the process of soil organic carbon cycle. Based on the long-term monitoring of soil erosion, and by the methods of soil particle size fractionation, this paper studied the effects of different land use types (wasteland, pinewood land, and grassland) on the distribution of organic carbon content in different sized soil particles and its relationships to the herb biomass. Land use type and slope position had obvious effects on the organic carbon content in different sized soil particles, and the organic carbon content was in the order of grassland > pinewood land > wasteland. The proportion of the organic carbon in different sized soil particles was mainly depended on the land use type, and had little relationships with slope position. According to the analysis of the ratio of particle-associated organic carbon to mineral-associated organic carbon (POC/MOC), the soil organic carbon in grassland was easily to be mineralized, whereas that in wasteland and pinewood land was relatively stable. On the slopes mainly in hilly red soil region, the soil organic carbon in sand fraction had great effects on herb biomass.

  5. In-situ observation of sputtered particles for carbon implanted tungsten during energetic isotope ion implantation

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Oya, Y.; Sato, M.; Uchimura, H.

    2015-03-15

    Tungsten is a candidate for plasma facing materials in future fusion reactors. During DT plasma operations, carbon as an impurity will bombard tungsten, leading to the formation of tungsten-carbon (WC) layer and affecting tritium recycling behavior. The effect of carbon implantation for the dynamic recycling of deuterium, which demonstrates tritium recycling, including retention and sputtering, has been investigated using in-situ sputtered particle measurements. The C{sup +} implanted W, WC and HOPG were prepared and dynamic sputtered particles were measured during H{sub 2}{sup +} irradiation. It has been found that the major hydrocarbon species for C{sup +} implanted tungsten is CH{submore » 3}, while for WC and HOPG (Highly Oriented Pyrolytic Graphite) it is CH{sub 4}. The chemical state of hydrocarbon is controlled by the H concentration in a W-C mixed layer. The amount of C-H bond and the retention of H trapped by carbon atom should control the chemical form of hydrocarbon sputtered by H{sub 2}{sup +} irradiation and the desorption of CH{sub 3} and CH{sub 2} are due to chemical sputtering, although that for CH is physical sputtering. The activation energy for CH{sub 3} desorption has been estimated to be 0.4 eV, corresponding to the trapping process of hydrogen by carbon through the diffusion in W. It is concluded that the chemical states of hydrocarbon sputtered by H{sub 2}{sup +} irradiation for W is determined by the amount of C-H bond on the W surface. (authors)« less

  6. Movement of particles using sequentially activated dielectrophoretic particle trapping

    DOEpatents

    Miles, Robin R.

    2004-02-03

    Manipulation of DNA and cells/spores using dielectrophoretic (DEP) forces to perform sample preparation protocols for polymerized chain reaction (PCR) based assays for various applications. This is accomplished by movement of particles using sequentially activated dielectrophoretic particle trapping. DEP forces induce a dipole in particles, and these particles can be trapped in non-uniform fields. The particles can be trapped in the high field strength region of one set of electrodes. By switching off this field and switching on an adjacent electrodes, particles can be moved down a channel with little or no flow.

  7. Characterization of activated carbons from oil-palm shell by CO2 activation with no holding carbonization temperature.

    PubMed

    Herawan, S G; Hadi, M S; Ayob, Md R; Putra, A

    2013-01-01

    Activated carbons can be produced from different precursors, including coals of different ranks, and lignocellulosic materials, by physical or chemical activation processes. The objective of this paper is to characterize oil-palm shells, as a biomass byproduct from palm-oil mills which were converted into activated carbons by nitrogen pyrolysis followed by CO2 activation. The effects of no holding peak pyrolysis temperature on the physical characteristics of the activated carbons are studied. The BET surface area of the activated carbon is investigated using N2 adsorption at 77 K with selected temperatures of 500, 600, and 700°C. These pyrolysis conditions for preparing the activated carbons are found to yield higher BET surface area at a pyrolysis temperature of 700°C compared to selected commercial activated carbon. The activated carbons thus result in well-developed porosities and predominantly microporosities. By using this activation method, significant improvement can be obtained in the surface characteristics of the activated carbons. Thus this study shows that the preparation time can be shortened while better results of activated carbon can be produced.

  8. Brown Carbon Production in Ammonium- or Amine-Containing Aerosol Particles by Reactive Uptake of Methylglyoxal and Photolytic Cloud Cycling.

    PubMed

    De Haan, David O; Hawkins, Lelia N; Welsh, Hannah G; Pednekar, Raunak; Casar, Jason R; Pennington, Elyse A; de Loera, Alexia; Jimenez, Natalie G; Symons, Michael A; Zauscher, Melanie; Pajunoja, Aki; Caponi, Lorenzo; Cazaunau, Mathieu; Formenti, Paola; Gratien, Aline; Pangui, Edouard; Doussin, Jean-François

    2017-07-05

    The effects of methylglyoxal uptake on the physical and optical properties of aerosol containing amines or ammonium sulfate were determined before and after cloud processing in a temperature- and RH-controlled chamber. The formation of brown carbon was observed upon methylglyoxal addition, detected as an increase in water-soluble organic carbon mass absorption coefficients below 370 nm and as a drop in single-scattering albedo at 450 nm. The imaginary refractive index component k 450 reached a maximum value of 0.03 ± 0.009 with aqueous glycine aerosol particles. Browning of solid particles occurred at rates limited by chamber mixing (<1 min), and in liquid particles occurred more gradually, but in all cases occurred much more rapidly than in bulk aqueous studies. Further browning in AS and methylammonium sulfate seeds was triggered by cloud events with chamber lights on, suggesting photosensitized brown carbon formation. Despite these changes in optical aerosol characteristics, increases in dried aerosol mass were rarely observed (<1 μg/m 3 in all cases), consistent with previous experiments on methylglyoxal. Under dry, particle-free conditions, methylglyoxal reacted (presumably on chamber walls) with methylamine with a rate constant k = (9 ± 2) × 10 -17 cm 3 molecule -1 s -1 at 294 K and activation energy E a = 64 ± 37 kJ/mol.

  9. Synthesis, characterization and photocatalytic activity of neodymium carbonate and neodymium oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Pourmortazavi, Seied Mahdi; Rahimi-Nasrabadi, Mehdi; Aghazadeh, Mustafa; Ganjali, Mohammad Reza; Karimi, Meisam Sadeghpour; Norouzi, Parviz

    2017-12-01

    This work focuses on the application of an orthogonal array design to the optimization of the facile direct carbonization reaction for the synthesis of neodymium carbonate nanoparticles, were the product particles are prepared based on the direct precipitation of their ingredients. To optimize the method the influences of the major operating conditions on the dimensions of the neodymium carbonate particles were quantitatively evaluated through the analysis of variance (ANOVA). It was observed that the crystalls of the carbonate salt can be synthesized by controlling neodymium concentration and flow rate, as well as reactor temperature. Based on the results of ANOVA, 0.03 M, 2.5 mL min-1 and 30 °C are the optimum values for the above-mentioend parameters and controlling the parameters at these values yields nanoparticles with the sizes of about of 31 ± 2 nm. The product of this former stage was next used as the feed for a thermal decomposition procedure which yielding neodymium oxide nanoparticles. The products were studied through X-ray diffraction (XRD), SEM, TEM, FT-IR and thermal analysis techniques. In addition, the photocatalytic activity of dyspersium carbonate and dyspersium oxide nanoparticles were investigated using degradation of methyl orange (MO) under ultraviolet light.

  10. Webinar Presentation: Particle-Resolved Simulations for Quantifying Black Carbon Climate Impact and Model Uncertainty

    EPA Pesticide Factsheets

    This presentation, Particle-Resolved Simulations for Quantifying Black Carbon Climate Impact and Model Uncertainty, was given at the STAR Black Carbon 2016 Webinar Series: Changing Chemistry over Time held on Oct. 31, 2016.

  11. Production of palm kernel shell-based activated carbon by direct physical activation for carbon dioxide adsorption.

    PubMed

    Rashidi, Nor Adilla; Yusup, Suzana

    2018-05-09

    The feasibility of biomass-based activated carbons has received a huge attention due to their excellent characteristics such as inexpensiveness, good adsorption behaviour and potential to reduce a strong dependency towards non-renewable precursors. Therefore, in this research work, eco-friendly activated carbon from palm kernel shell that has been produced from one-stage physical activation by using the Box-Behnken design of Response Surface Methodology is highlighted. The effect of three input parameters-temperature, dwell time and gas flow rate-towards product yield and carbon dioxide (CO 2 ) uptake at room temperature and atmospheric pressure are studied. Model accuracy has been evaluated through the ANOVA analysis and lack-of-fit test. Accordingly, the optimum condition in synthesising the activated carbon with adequate CO 2 adsorption capacity of 2.13 mmol/g and product yield of 25.15 wt% is found at a temperature of 850 °C, holding time of 60 min and CO 2 flow rate of 450 cm 3 /min. The synthesised activated carbon has been characterised by diverse analytical instruments including thermogravimetric analyser, scanning electron microscope, as well as N 2 adsorption-desorption isotherm. The characterisation analysis indicates that the synthesised activated carbon has higher textural characteristics and porosity, together with better thermal stability and carbon content as compared to pristine palm kernel shell. Activated carbon production via one-step activation approach is economical since its carbon yield is within the industrial target, whereas CO 2 uptake is comparable to the synthesised activated carbon from conventional dual-stage activation, commercial activated carbon and other published data from literature.

  12. Catalytic activation of carbon-carbon bonds in cyclopentanones.

    PubMed

    Xia, Ying; Lu, Gang; Liu, Peng; Dong, Guangbin

    2016-11-24

    In the chemical industry, molecules of interest are based primarily on carbon skeletons. When synthesizing such molecules, the activation of carbon-carbon single bonds (C-C bonds) in simple substrates is strategically important: it offers a way of disconnecting such inert bonds, forming more active linkages (for example, between carbon and a transition metal) and eventually producing more versatile scaffolds. The challenge in achieving such activation is the kinetic inertness of C-C bonds and the relative weakness of newly formed carbon-metal bonds. The most common tactic starts with a three- or four-membered carbon-ring system, in which strain release provides a crucial thermodynamic driving force. However, broadly useful methods that are based on catalytic activation of unstrained C-C bonds have proven elusive, because the cleavage process is much less energetically favourable. Here we report a general approach to the catalytic activation of C-C bonds in simple cyclopentanones and some cyclohexanones. The key to our success is the combination of a rhodium pre-catalyst, an N-heterocyclic carbene ligand and an amino-pyridine co-catalyst. When an aryl group is present in the C3 position of cyclopentanone, the less strained C-C bond can be activated; this is followed by activation of a carbon-hydrogen bond in the aryl group, leading to efficient synthesis of functionalized α-tetralones-a common structural motif and versatile building block in organic synthesis. Furthermore, this method can substantially enhance the efficiency of the enantioselective synthesis of some natural products of terpenoids. Density functional theory calculations reveal a mechanism involving an intriguing rhodium-bridged bicyclic intermediate.

  13. CARDIOVASCULAR RESPONSES TO ULTRAFINE CARBON PARTICLE EXPOSURES IN RATS

    EPA Science Inventory

    TD-02-042 (U. KODAVANTI) GPRA # 10108

    Cardiovascular Responses to Ultrafine Carbon Particle Exposures in Rats.
    V. Harder1, B. Lentner1, A. Ziesenis1, E. Karg1, L. Ruprecht1, U. Kodavanti2, A. Stampfl3, J. Heyder1, H. Schulz1
    GSF- Institute for Inhalation Biology1, I...

  14. Effect of calcium carbonate particle shape on phagocytosis and pro-inflammatory response in differentiated THP-1 macrophages.

    PubMed

    Tabei, Yosuke; Sugino, Sakiko; Eguchi, Kenichiro; Tajika, Masahiko; Abe, Hiroko; Nakajima, Yoshihiro; Horie, Masanori

    2017-08-19

    Phagocytosis is a physiological process used by immune cells such as macrophages to actively ingest and destroy foreign pathogens and particles. It is the cellular process that leads to the failure of drug delivery carriers because the drug carriers are cleared by immune cells before reaching their target. Therefore, clarifying the mechanism of particle phagocytosis would have a significant implication for both fundamental understanding and biomedical engineering. As far as we know, the effect of particle shape on biological response has not been fully investigated. In the present study, we investigated the particle shape-dependent cellular uptake and biological response of differentiated THP-1 macrophages by using calcium carbonate (CaCO 3 )-based particles as a model. Transmission electron microscopy analysis revealed that the high uptake of needle-shaped CaCO 3 particles by THP-1 macrophages because of their high phagocytic activity. In addition, the THP-1 macrophages exposed to needle-shaped CaCO 3 accumulated a large amount of calcium in the intracellular matrix. The enhanced release of interleukin-8 (IL-8) and tumor necrosis factor-alpha (TNF-α) by the THP-1 macrophages suggested that the needle-shaped CaCO 3 particles trigger a pro-inflammatory response. In contrast, no pro-inflammatory response was induced in undifferentiated THP-1 monocytes exposed to either needle- or cuboidal-shaped CaCO 3 particles, probably because of their low phagocytic activity. We also found that phosphate-coated particles efficiently repressed cellular uptake and the resulting pro-inflammatory response in both THP-1 macrophages and primary peritoneal macrophages. Our results indicate that the pro-inflammatory response of macrophages upon exposure to CaCO 3 particles is shape- and surface property-dependent, and is mediated by the intracellular accumulation of calcium ions released from phagocytosed CaCO 3 particles. Copyright © 2017 Elsevier Inc. All rights reserved.

  15. Amorphous calcium carbonate particles form coral skeletons

    DOE PAGES

    Mass, Tali; Giuffre, Anthony J.; Sun, Chang -Yu; ...

    2017-08-28

    Do corals form their skeletons by precipitation from solution or by attachment of amorphous precursor particles as observed in other minerals and biominerals? The classical model assumes precipitation in contrast with observed “vital effects,” that is, deviations from elemental and isotopic compositions at thermodynamic equilibrium. Here, we show direct spectromicroscopy evidence in Stylophora pistillata corals that two amorphous precursors exist, one hydrated and one anhydrous amorphous calcium carbonate (ACC); that these are formed in the tissue as 400-nm particles; and that they attach to the surface of coral skeletons, remain amorphous for hours, and finally, crystallize into aragonite (CaCO 3).more » We show in both coral and synthetic aragonite spherulites that crystal growth by attachment of ACC particles is more than 100 times faster than ion-by-ion growth from solution. Fast growth provides a distinct physiological advantage to corals in the rigors of the reef, a crowded and fiercely competitive ecosystem. Corals are affected by warming-induced bleaching and postmortem dissolution, but the finding here that ACC particles are formed inside tissue may make coral skeleton formation less susceptible to ocean acidification than previously assumed. If this is how other corals form their skeletons, perhaps this is how a few corals survived past CO 2 increases, such as the Paleocene–Eocene Thermal Maximum that occurred 56 Mya.« less

  16. Amorphous calcium carbonate particles form coral skeletons

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Mass, Tali; Giuffre, Anthony J.; Sun, Chang -Yu

    Do corals form their skeletons by precipitation from solution or by attachment of amorphous precursor particles as observed in other minerals and biominerals? The classical model assumes precipitation in contrast with observed “vital effects,” that is, deviations from elemental and isotopic compositions at thermodynamic equilibrium. Here, we show direct spectromicroscopy evidence in Stylophora pistillata corals that two amorphous precursors exist, one hydrated and one anhydrous amorphous calcium carbonate (ACC); that these are formed in the tissue as 400-nm particles; and that they attach to the surface of coral skeletons, remain amorphous for hours, and finally, crystallize into aragonite (CaCO 3).more » We show in both coral and synthetic aragonite spherulites that crystal growth by attachment of ACC particles is more than 100 times faster than ion-by-ion growth from solution. Fast growth provides a distinct physiological advantage to corals in the rigors of the reef, a crowded and fiercely competitive ecosystem. Corals are affected by warming-induced bleaching and postmortem dissolution, but the finding here that ACC particles are formed inside tissue may make coral skeleton formation less susceptible to ocean acidification than previously assumed. If this is how other corals form their skeletons, perhaps this is how a few corals survived past CO 2 increases, such as the Paleocene–Eocene Thermal Maximum that occurred 56 Mya.« less

  17. Amorphous calcium carbonate particles form coral skeletons

    NASA Astrophysics Data System (ADS)

    Mass, Tali; Giuffre, Anthony J.; Sun, Chang-Yu; Stifler, Cayla A.; Frazier, Matthew J.; Neder, Maayan; Tamura, Nobumichi; Stan, Camelia V.; Marcus, Matthew A.; Gilbert, Pupa U. P. A.

    2017-09-01

    Do corals form their skeletons by precipitation from solution or by attachment of amorphous precursor particles as observed in other minerals and biominerals? The classical model assumes precipitation in contrast with observed “vital effects,” that is, deviations from elemental and isotopic compositions at thermodynamic equilibrium. Here, we show direct spectromicroscopy evidence in Stylophora pistillata corals that two amorphous precursors exist, one hydrated and one anhydrous amorphous calcium carbonate (ACC); that these are formed in the tissue as 400-nm particles; and that they attach to the surface of coral skeletons, remain amorphous for hours, and finally, crystallize into aragonite (CaCO3). We show in both coral and synthetic aragonite spherulites that crystal growth by attachment of ACC particles is more than 100 times faster than ion-by-ion growth from solution. Fast growth provides a distinct physiological advantage to corals in the rigors of the reef, a crowded and fiercely competitive ecosystem. Corals are affected by warming-induced bleaching and postmortem dissolution, but the finding here that ACC particles are formed inside tissue may make coral skeleton formation less susceptible to ocean acidification than previously assumed. If this is how other corals form their skeletons, perhaps this is how a few corals survived past CO2 increases, such as the Paleocene-Eocene Thermal Maximum that occurred 56 Mya.

  18. Amorphous calcium carbonate particles form coral skeletons.

    PubMed

    Mass, Tali; Giuffre, Anthony J; Sun, Chang-Yu; Stifler, Cayla A; Frazier, Matthew J; Neder, Maayan; Tamura, Nobumichi; Stan, Camelia V; Marcus, Matthew A; Gilbert, Pupa U P A

    2017-09-12

    Do corals form their skeletons by precipitation from solution or by attachment of amorphous precursor particles as observed in other minerals and biominerals? The classical model assumes precipitation in contrast with observed "vital effects," that is, deviations from elemental and isotopic compositions at thermodynamic equilibrium. Here, we show direct spectromicroscopy evidence in Stylophora pistillata corals that two amorphous precursors exist, one hydrated and one anhydrous amorphous calcium carbonate (ACC); that these are formed in the tissue as 400-nm particles; and that they attach to the surface of coral skeletons, remain amorphous for hours, and finally, crystallize into aragonite (CaCO 3 ). We show in both coral and synthetic aragonite spherulites that crystal growth by attachment of ACC particles is more than 100 times faster than ion-by-ion growth from solution. Fast growth provides a distinct physiological advantage to corals in the rigors of the reef, a crowded and fiercely competitive ecosystem. Corals are affected by warming-induced bleaching and postmortem dissolution, but the finding here that ACC particles are formed inside tissue may make coral skeleton formation less susceptible to ocean acidification than previously assumed. If this is how other corals form their skeletons, perhaps this is how a few corals survived past CO 2 increases, such as the Paleocene-Eocene Thermal Maximum that occurred 56 Mya.

  19. Amorphous calcium carbonate particles form coral skeletons

    PubMed Central

    Mass, Tali; Giuffre, Anthony J.; Sun, Chang-Yu; Stifler, Cayla A.; Frazier, Matthew J.; Neder, Maayan; Tamura, Nobumichi; Stan, Camelia V.; Marcus, Matthew A.

    2017-01-01

    Do corals form their skeletons by precipitation from solution or by attachment of amorphous precursor particles as observed in other minerals and biominerals? The classical model assumes precipitation in contrast with observed “vital effects,” that is, deviations from elemental and isotopic compositions at thermodynamic equilibrium. Here, we show direct spectromicroscopy evidence in Stylophora pistillata corals that two amorphous precursors exist, one hydrated and one anhydrous amorphous calcium carbonate (ACC); that these are formed in the tissue as 400-nm particles; and that they attach to the surface of coral skeletons, remain amorphous for hours, and finally, crystallize into aragonite (CaCO3). We show in both coral and synthetic aragonite spherulites that crystal growth by attachment of ACC particles is more than 100 times faster than ion-by-ion growth from solution. Fast growth provides a distinct physiological advantage to corals in the rigors of the reef, a crowded and fiercely competitive ecosystem. Corals are affected by warming-induced bleaching and postmortem dissolution, but the finding here that ACC particles are formed inside tissue may make coral skeleton formation less susceptible to ocean acidification than previously assumed. If this is how other corals form their skeletons, perhaps this is how a few corals survived past CO2 increases, such as the Paleocene–Eocene Thermal Maximum that occurred 56 Mya. PMID:28847944

  20. Effect of indirect non-thermal plasma on particle size distribution and composition of diesel engine particles

    NASA Astrophysics Data System (ADS)

    Linbo, GU; Yixi, CAI; Yunxi, SHI; Jing, WANG; Xiaoyu, PU; Jing, TIAN; Runlin, FAN

    2017-11-01

    To explore the effect of the gas source flow rate on the actual diesel exhaust particulate matter (PM), a test bench for diesel engine exhaust purification was constructed, using indirect non-thermal plasma technology. The effects of different gas source flow rates on the quantity concentration, composition, and apparent activation energy of PM were investigated, using an engine exhaust particle sizer and a thermo-gravimetric analyzer. The results show that when the gas source flow rate was large, not only the maximum peak quantity concentrations of particles had a large drop, but also the peak quantity concentrations shifted to smaller particle sizes from 100 nm to 80 nm. When the gas source flow rate was 10 L min-1, the total quantity concentration greatly decreased where the removal rate of particles was 79.2%, and the variation of the different mode particle proportion was obvious. Non-thermal plasma (NTP) improved the oxidation ability of volatile matter as well as that of solid carbon. However, the NTP gas source rate had little effects on oxidation activity of volatile matter, while it strongly influenced the oxidation activity of solid carbon. Considering the quantity concentration and oxidation activity of particles, a gas source flow rate of 10 L min-1 was more appropriate for the purification of particles.

  1. Removal of polybrominated diphenyl ethers by biomass carbon-supported nanoscale zerovalent iron particles: influencing factors, kinetics, and mechanism.

    PubMed

    Fu, Rongbing; Xu, Zhen; Peng, Lin; Bi, Dongsu

    2016-12-01

    In this study, nanoscale zerovalent iron (NZVI) immobilized on biomass carbon was used for the high efficient removal of BDE 209. NZVI supported on biomass carbon minimized the aggregation of NZVI particles resulting in the increased reaction performance. The proposed removal mechanism included the adsorption of BDE 209 on the surface or interior of the biomass carbon NZVI (BC-NZVI) particles and the subsequent debromination of BDE 209 by NZVI while biomass carbon served as an electron shuttle. BC-NZVI particles and the interaction between BC-NZVI particles and BDE 209 were characterized by TEM, XRD, and XPS. The removal reaction followed a pseudo-first-order rate expression under different reaction conditions, and the k obs was higher than that of other NZVI-supported materials. The debromination of BDE 209 by BC-NZVI was a stepwise process from nona-BDE to DE. A proposed pathway suggested that supporting NZVI on biomass carbon has potential as a promising technique for in situ organic-contaminated groundwater remediation.

  2. Forces in inhomogeneous open active-particle systems.

    PubMed

    Razin, Nitzan; Voituriez, Raphael; Elgeti, Jens; Gov, Nir S

    2017-11-01

    We study the force that noninteracting pointlike active particles apply to a symmetric inert object in the presence of a gradient of activity and particle sources and sinks. We consider two simple patterns of sources and sinks that are common in biological systems. We analytically solve a one-dimensional model designed to emulate higher-dimensional systems, and study a two-dimensional model by numerical simulations. We specify when the particle flux due to the creation and annihilation of particles can act to smooth the density profile that is induced by a gradient in the velocity of the active particles, and find the net resultant force due to both the gradient in activity and the particle flux. These results are compared qualitatively to observations of nuclear motion inside the oocyte, that is driven by a gradient in activity of actin-coated vesicles.

  3. Improve the catalytic activity of {alpha}-Fe{sub 2}O{sub 3} particles in decomposition of ammonium perchlorate by coating amorphous carbon on their surface

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zhang Yifu; Liu Xinghai, E-mail: liuxh@whu.edu.c; Nie Jiaorong

    2011-02-15

    Sphere- and pod-like {alpha}-Fe{sub 2}O{sub 3} particles have been selectively synthesized using NH{sub 3}.H{sub 2}O and NaOH solution to adjust the pH value of the designed synthetic system, respectively. The sphere-like {alpha}-Fe{sub 2}O{sub 3} particles with diameter about 25 nm on average were encapsulated into carbon shells to fabricate a novel core-shell composite ({alpha}-Fe{sub 2}O{sub 3}-C) through the coating experiments. The catalytic performance of the products on the thermal decomposition of ammonium perchlorate (AP) was investigated by thermal gravimetric analyzer (TG) and differential thermal analysis (DTA). The thermal decomposition temperatures of AP in the presence of pod-like {alpha}-Fe{sub 2}O{sub 3},more » sphere-like {alpha}-Fe{sub 2}O{sub 3} and {alpha}-Fe{sub 2}O{sub 3}-C are reduced by 72, 81 and 109 {sup o}C, respectively, which show that {alpha}-Fe{sub 2}O{sub 3}-C core-shell composites have higher catalytic activity than that of {alpha}-Fe{sub 2}O{sub 3}. -- Graphical abstract: The catalytic performance of pod-like {alpha}-Fe{sub 2}O{sub 3}, sphere-like {alpha}-Fe{sub 2}O{sub 3} and {alpha}-Fe{sub 2}O{sub 3}-C on the thermal decomposition of ammonium perchlorate (AP). Display Omitted Research highlights: {yields} Sphere- and pod-like {alpha}-Fe{sub 2}O{sub 3} particles have been selectively synthesized using NH{sub 3}.H{sub 2}O and NaOH solution to adjust the pH value. {yields} A novel core-shell composite ({alpha}-Fe{sub 2}O{sub 3}-C core-shell structured composite) has been successfully synthesized using sphere-like {alpha}-Fe{sub 2}O{sub 3} particles as the cores and glucose as the source of carbon. {yields} The thermal decomposition temperatures of AP in the presence of pod-like {alpha}-Fe{sub 2}O{sub 3}, sphere-like {alpha}-Fe{sub 2}O{sub 3} and {alpha}-Fe{sub 2}O{sub 3}-C are reduced by 72, 81 and 109 {sup o}C, respectively, which shows that these materials have high catalytic activity.« less

  4. Effect of sulfate and carbonate minerals on particle-size distributions in arid soils

    USGS Publications Warehouse

    Goossens, Dirk; Buck, Brenda J.; Teng, Yuazxin; Robins, Colin; Goldstein, Harland L.

    2014-01-01

    Arid soils pose unique problems during measurement and interpretation of particle-size distributions (PSDs) because they often contain high concentrations of water-soluble salts. This study investigates the effects of sulfate and carbonate minerals on grain-size analysis by comparing analyses in water, in which the minerals dissolve, and isopropanol (IPA), in which they do not. The presence of gypsum, in particular, substantially affects particle-size analysis once the concentration of gypsum in the sample exceeds the mineral’s solubility threshold. For smaller concentrations particle-size results are unaffected. This is because at concentrations above the solubility threshold fine particles cement together or bind to coarser particles or aggregates already present in the sample, or soluble mineral coatings enlarge grains. Formation of discrete crystallites exacerbates the problem. When soluble minerals are dissolved the original, insoluble grains will become partly or entirely liberated. Thus, removing soluble minerals will result in an increase in measured fine particles. Distortion of particle-size analysis is larger for sulfate minerals than for carbonate minerals because of the much higher solubility in water of the former. When possible, arid soils should be analyzed using a liquid in which the mineral grains do not dissolve, such as IPA, because the results will more accurately reflect the PSD under most arid soil field conditions. This is especially important when interpreting soil and environmental processes affected by particle size.

  5. Carbon-encapsulated cobalt nanoparticles: synthesis, properties, and magnetic particle hyperthermia efficiency

    NASA Astrophysics Data System (ADS)

    Kotoulas, A.; Dendrinou-Samara, C.; Sarafidis, C.; Kehagias, Th.; Arvanitidis, J.; Vourlias, G.; Angelakeris, M.; Kalogirou, Orestis

    2017-12-01

    A facile and low-cost method for structuring carbon-encapsulated cobalt nanoparticles (Co@C) is presented. Three samples were solvothermally prepared in one step at 220 °C and one in two steps at 200 °C. Three different polyols such as propylene glycol, triethylene glycol, and tetraethylene glycol were used as carbon sources, solvents, and reducing agents. The samples were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), and Raman spectroscopy. Concerning the crystal structure of the particles, a mixture of hcp/ fcc Co phases was obtained in three of the samples, independently of the polyol used. The coexistence of cubic and hexagonal phases was revealed both from XRD and high-resolution TEM (HRTEM). The formation of the cubic fcc structure, despite the relatively low reaction temperature, is attributed to the role of the interface between carbon coating and metallic core. The presence of carbon coating was demonstrated by Raman spectrometry, exhibiting the characteristic D and G graphitic bands, and by HRTEM observations. All samples showed ferromagnetic behavior with saturation magnetization up to 158 emu/g and coercivity up to 206 Oe. From the magnetic particle hyperthermia measurements recorded at a frequency of 765 kHz, a maximum SLP value of 241 W/g was obtained.

  6. Ignitability of Diesel Fuel with an Inclusion of Ultrafine Carbon Particles

    NASA Astrophysics Data System (ADS)

    Krivosheev, P. N.; Leshchevich, V. V.; Shimchenko, S. Yu.; Shushkov, S. V.; Penyazkov, O. G.

    2017-11-01

    Nanosize carbon fuel additions were synthesized by the action of an electric discharge on a diesel fuel. Depending on the discharge regime, variously shaped carbon particles, including planar graphitized ones, were formed in the fuel. Ignitability of the produced samples was assessed by the method of initiation of a foamed fuel sample by a lowcurrent electric arc. The modified fuel showed the improvement of the ignition characteristics in the presence of a nanodispersed solid phase.

  7. Micro-milling of spent granular activated carbon for its possible reuse as an adsorbent: Remaining capacity and characteristics.

    PubMed

    Pan, Long; Takagi, Yuichi; Matsui, Yoshihiko; Matsushita, Taku; Shirasaki, Nobutaka

    2017-05-01

    We milled granular activated carbons (GACs) that had been used for 0-9 years in water treatment plants and produced carbon particles with different sizes and ages: powdered activated carbons (PAC, median diameter 12-42 μm), superfine PAC (SPAC, 0.9-3.5 μm), and submicron-sized SPAC (SSPAC, 220-290 nm). The fact that SPAC produced from 1-year-old GAC and SSPAC from 2-year-old GAC removed 2-methylisoborneol (MIB) from water with an efficiency similar to that of virgin PAC after a carbon contact time of 30 min suggests that spent GAC could be reused for water treatment after being milled. This potential for reuse was created by increasing the equilibrium adsorption capacity via reduction of the carbon particle size and improving the adsorption kinetics. During long-term (>1 year) use in GAC beds, the volume of pores in the carbon, particularly pores with widths of 0.6-0.9 nm, was greatly reduced. The equilibrium adsorption capacities of the carbon for compounds with molecular sizes in this range could therefore decrease with increasing carbon age. Among these compounds, the decreases of capacities were prominent for hydrophobic compounds, including MIB. For hydrophobic compounds, however, the equilibrium adsorption capacities could be increased with decreasing carbon particle size. The iodine number, among other indices, was best correlated with the equilibrium adsorption capacity of the MIB and would be a good index to assess the remaining MIB adsorption capacity of spent carbon. Spent GAC can possibly be reused as SPAC or SSPAC if its iodine number is ≥ 600 mg/g. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. 13C NMR spectroscopy characterization of particle-size fractionated soil organic carbon in subalpine forest and grassland ecosystems.

    PubMed

    Shiau, Yo-Jin; Chen, Jenn-Shing; Chung, Tay-Lung; Tian, Guanglong; Chiu, Chih-Yu

    2017-12-01

    Soil organic carbon (SOC) and carbon (C) functional groups in different particle-size fractions are important indicators of microbial activity and soil decomposition stages under wildfire disturbances. This research investigated a natural Tsuga forest and a nearby fire-induced grassland along a sampling transect in Central Taiwan with the aim to better understand the effect of forest wildfires on the change of SOC in different soil particle scales. Soil samples were separated into six particle sizes and SOC was characterized by solid-state 13 C nuclear magnetic resonance spectroscopy in each fraction. The SOC content was higher in forest than grassland soil in the particle-size fraction samples. The O-alkyl-C content (carbohydrate-derived structures) was higher in the grassland than the forest soils, but the alkyl-C content (recalcitrant substances) was higher in forest than grassland soils, for a higher humification degree (alkyl-C/O-alkyl-C ratio) in forest soils for all the soil particle-size fractions. High humification degree was found in forest soils. The similar aromaticity between forest and grassland soils might be attributed to the fire-induced aromatic-C content in the grassland that offsets the original difference between the forest and grassland. High alkyl-C content and humification degree and low C/N ratios in the fine particle-size fractions implied that undecomposed recalcitrant substances tended to accumulate in the fine fractions of soils.

  9. Higher-order force moments of active particles

    NASA Astrophysics Data System (ADS)

    Nasouri, Babak; Elfring, Gwynn J.

    2018-04-01

    Active particles moving through fluids generate disturbance flows due to their activity. For simplicity, the induced flow field is often modeled by the leading terms in a far-field approximation of the Stokes equations, whose coefficients are the force, torque, and stresslet (zeroth- and first-order force moments) of the active particle. This level of approximation is quite useful, but may also fail to predict more complex behaviors that are observed experimentally. In this study, to provide a better approximation, we evaluate the contribution of the second-order force moments to the flow field and, by reciprocal theorem, present explicit formulas for the stresslet dipole, rotlet dipole, and potential dipole for an arbitrarily shaped active particle. As examples of this method, we derive modified Faxén laws for active spherical particles and resolve higher-order moments for active rod-like particles.

  10. THE INFLUENCE OF CARBON BURNOUT ON SUBMICRON PARTICLE FORMATION FROM EMULSIFIED FUEL OIL COMBUSTION

    EPA Science Inventory

    The paper gives results of an examination of particle behavior and particle size distributions from the combustion of different fuel oils and emulsified fuels in three experimental combusators. Results indicate that improved carbon (C) burnout from fule oil combustion, either by...

  11. MULTIYEAR REAL-TIME MONITORING OF PARTICLES, PAH, AND BLACK CARBON IN AN OCCUPIED HOUSE

    EPA Science Inventory

    Concentrations of ultrafine, fine, and coarse particles, particle-bound polycyclic aromatic hydrocarbons (PAH), and black carbon have been measured continuously (every 1 to 5 minutes) in an occupied townhouse for 2-3 years. Also, since the summer of 1999, temperature (outdoors...

  12. Particle-associated extracellular enzyme activity and bacterial community composition across the Canadian Arctic Ocean.

    PubMed

    Kellogg, Colleen T E; Deming, Jody W

    2014-08-01

    Microbial enzymatic hydrolysis of marine-derived particulate organic carbon (POC) can be a dominant mechanism for attenuating carbon flux in cold Arctic waters during spring and summer. Whether this mechanism depends on composition of associated microbial communities and extends into other seasons is not known. Bacterial community composition (BCC) and extracellular enzyme activity (EEA, for leucine aminopeptidases, glucosidases and chitobiases) were measured on small suspended particles and potentially sinking aggregates collected during fall from waters of the biologically productive North Water and river-impacted Beaufort Sea. Although other environmental variables appeared influential, both BCC and EEA varied along a marine productivity gradient in the two regions. Aggregates harbored the most distinctive bacterial communities, with a small number of taxa driving differences between particle-size classes (1.0-60 and > 60 μm) and free-living bacteria (0.2-1.0 μm). Significant relationships between patterns in particle-associated BCC and EEA suggest strong links between these two variables. Calculations indicated that up to 80% of POC in the euphotic zone of the North Water, and 20% in the Beaufort Sea, may be hydrolyzed enzymatically, underscoring the importance of this mechanism in attenuating carbon fluxes in Arctic waters even as winter approaches. © 2014 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

  13. Wintertime Correlation Between Black Carbon and Particle Size in a Street and Rural Site in Santiago de Chile

    NASA Astrophysics Data System (ADS)

    Gramsch, E. V.; Reyes, F.; Oyola, P.

    2013-05-01

    We have studied the correlation between black carbon and particle size in three sites in the Metropolitan area of Santiago de Chile in the winter of 2009 and performed a detailed comparison. Two of the sites are located near busy streets in Santiago de Chile. The other site was located in a rural area about 30 km upwind from downtown with little influence from vehicles, but large influence from wood burning. The particle size distribution was measured with a DMPS (Whalin, 2001) in the range from 10 to 700 nm. Simultaneously, black carbon was measured with an optical monitor developed at the University of Santiago (Gramsch, 2004). It is well known that the smaller particles (~ 10 - 40 nm ) are emitted directly by the engines of vehicles, which later condensate or coagulate in the atmosphere to form larger particles. In our measurements, the street site is mostly influenced by diesel vehicles which emit large amounts of black carbon. We have divided the particle size measurements in four groups (10 - 40 nm, 41- 69 nm, 79 - 157 nm and 190 - 700 nm) in order to compare with the carbon monitor. The highest correlation (0.98) in the site near the street between black carbon and the particles was obtained with the 190 - 700 nm. The correlation with the 79 - 157 nm group was slightly less (0.93). A comparison between the hourly average curves for black carbon and the 190 - 700 nm group show a similar shape during the whole day. In the rural site, the number of particles in the 10 - 40 nm group was 10 times lower than in the street, but the number of particles in the 190 - 700 nm group was only two times smaller. This fact is an indication that wood burning does not generate particles smaller than ~ 80 - 100 nm. The best correlation in the rural site between the black carbon and the particles was also with the 190 - 700 nm group. However, the correlation was lower (0.86) than in the street site. The hourly average curves for black carbon and the 190 - 700 nm group show a

  14. Synthesis of MOF-525 Derived Nanoporous Carbons with Different Particle Sizes for Supercapacitor Application.

    PubMed

    Chang, Ting-Hsiang; Young, Christine; Lee, Min-Han; Salunkhe, Rahul R; Alshehri, Saad M; Ahamad, Tansir; Islam, Md Tofazzal; Wu, Kevin C-W; Hossain, Md Shahriar A; Yamauchi, Yusuke; Ho, Kuo-Chuan

    2017-11-02

    Nanoporous carbon (NC) materials have attracted great research interest for supercapacitor applications, because of their excellent electrochemical and mechanical stability, good electrical conductivity, and high surface area. Although there are many reports on metal-organic framework (MOF)-derived carbon materials, previous synthetic studies have been hindered by imperfect control of particle sizes and shapes. Here, we show precise control of the particle sizes of MOF-525 from 100 nm to 750 nm. After conversion of MOF-525 to NC, the effects of variation of the particle size on the electrochemical performance have been carefully investigated. The results demonstrate that our NC is a potential candidate for practical supercapacitor applications. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Redox activity of urban quasi-ultrafine particles from primary and secondary sources

    NASA Astrophysics Data System (ADS)

    Verma, Vishal; Ning, Zhi; Cho, Arthur K.; Schauer, James J.; Shafer, Martin M.; Sioutas, Constantinos

    2009-12-01

    To characterize the redox activity profiles of atmospheric aerosols from primary (traffic) and secondary photochemical sources, ambient quasi-ultrafine particles were collected near downtown Los Angeles in two different time periods - morning (6:00-9:00 PDT) and afternoon (11:00-14:00 PDT) in the summer of 2008. Detailed chemical analysis of the collected samples, including water-soluble elements, inorganic ions, organic species and water soluble organic carbon (WSOC) was conducted and redox activity of the samples was measured by two different assays: the dithiothreitol (DTT) and the macrophage reactive oxygen species (ROS) assays. Tracers of secondary photochemical reactions, such as sulfate and organic acids were higher (2.1 ± 0.6 times for sulfate, and up to 3 times for the organic acids) in the afternoon period. WSOC was also elevated by 2.5 ± 0.9 times in the afternoon period due to photo-oxidation of primary particles during atmospheric aging. Redox activity measured by the DTT assay was considerably higher for the samples collected during the afternoon; on the other hand, diurnal trends in the ROS-based activity were not consistent between the morning and afternoon periods. A linear regression between redox activity and various PM chemical constituents showed that the DTT assay was highly correlated with WSOC ( R2 = 0.80), while ROS activity was associated mostly with water soluble transition metals (Vanadium, Nickel and Cadmium; R2 > 0.70). The DTT and ROS assays, which are based on the generation of different oxidizing species by chemical PM constituents, provide important information for elucidating the health risks related to PM exposure from different sources. Thus, both primary and secondary particles possess high redox activity; however, photochemical transformations of primary emissions with atmospheric aging enhance the toxicological potency of primary particles in terms of generating oxidative stress and leading to subsequent damage in cells.

  16. Carbon nanofibers grafted on activated carbon as an electrode in high-power supercapacitors.

    PubMed

    Gryglewicz, Grażyna; Śliwak, Agata; Béguin, François

    2013-08-01

    A hybrid electrode material for high-power supercapacitors was fabricated by grafting carbon nanofibers (CNFs) onto the surface of powdered activated carbon (AC) through catalytic chemical vapor deposition (CCVD). A uniform thin layer of disentangled CNFs with a herringbone structure was deposited on the carbon surface through the decomposition of propane at 450 °C over an AC-supported nickel catalyst. CNF coating was controlled by the reaction time and the nickel content. The superior CNF/AC composite displays excellent electrochemical performance in a 0.5 mol L(-1) solution of K2 SO4 due to its unique structure. At a high scan rate (100 mV s(-1) ) and current loading (20 A g(-1) ), the capacitance values were three- and fourfold higher than those for classical AC/carbon black composites. Owing to this feature, a high energy of 10 Wh kg(-1) was obtained over a wide power range in neutral medium at a voltage of 0.8 V. The significant enhancement of charge propagation is attributed to the presence of herringbone CNFs, which facilitate the diffusion of ions in the electrode and play the role of electronic bridges between AC particles. An in situ coating of AC with short CNFs (below 200 nm) is a very attractive method for producing the next generation of carbon composite materials with a high power performance in supercapacitors working in neutral medium. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Scaling trace organic contaminant adsorption capacity by granular activated carbon.

    PubMed

    Corwin, Christopher J; Summers, R Scott

    2010-07-15

    The role of particle size on the reduction of granular activated carbon (GAC) adsorption capacity for trace organic contaminants by dissolved organic matter (DOM) is examined and applied to performance scale-up. The adsorption capacity reduction, termed fouling, must be scalable in order to use bench scale tests, such as the rapid small-scale column test (RSSCT) to predict full-scale breakthrough. Equilibrium adsorption capacity tests with GAC preloaded with DOM and RSSCT breakthrough curves at three different GAC particle sizes indicate that GAC adsorption capacity is dependent on GAC particle size when DOM is present. Thus, the RSSCT cannot be expected to match full-scale results regardless of which RSSCT design approach is used (constant or proportional diffusivity), unless a scaling factor is applied to the results. Proportional diffusivity RSSCT breakthrough curves demonstrate that surface concentration of DOM is not a good measure of fouling. It is hypothesized that pore blockage is the mechanism responsible for the dependence on particle size. As GAC particle size increases, the microporous surface area behind a constricted pore also increases. The result is lower adsorption capacity per mass of adsorbent in the larger GAC particles. A scaling methodology for equilibrium and breakthrough data is presented that accounts for the dependence of NOM preloading effects on GAC particle diameter.

  18. A comparison of different activated carbon performances on catalytic ozonation of a model azo reactive dye.

    PubMed

    Gül, S; Eren, O; Kır, S; Onal, Y

    2012-01-01

    The objective of this study is to compare the performances of catalytic ozonation processes of two activated carbons prepared from olive stone (ACOS) and apricot stone (ACAS) with commercial ones (granular activated carbon-GAC and powder activated carbon-PAC) in degradation of reactive azo dye (Reactive Red 195). The optimum conditions (solution pH and amount of catalyst) were investigated by using absorbencies at 532, 220 and 280 nm wavelengths. Pore properties of the activated carbon (AC) such as BET surface area, pore volume, pore size distribution, and pore diameter were characterized by N(2) adsorption. The highest BET surface area carbon (1,275 m(2)/g) was obtained from ACOS with a particle size of 2.29 nm. After 2 min of catalytic ozonation, decolorization performances of ACOS and ACAS (90.4 and 91.3%, respectively) were better than that of GAC and PAC (84.6 and 81.2%, respectively). Experimental results showed that production of porous ACs with high surface area from olive and apricot stones is feasible in Turkey.

  19. On the formation of nanocrystalline active zinc oxide from zinc hydroxide carbonate

    NASA Astrophysics Data System (ADS)

    Moezzi, Amir; Cortie, Michael; Dowd, Annette; McDonagh, Andrew

    2014-04-01

    The decomposition of zinc hydroxide carbonate, Zn5(CO3)2(OH)6 (ZHC), into the high surface area form of ZnO known as "active zinc oxide" is examined. In particular, the nucleation and evolution of the ZnO nanocrystals is of interest as the size of these particles controls the activity of the product. The decomposition process was studied using X-ray diffraction, thermogravimetric analysis, scanning electron microscopy, transmission electron microscopy and BET surface area measurements. At about 240 °C ZHC decomposes to porous ZnO in a single step. The product material has a specific surface area in the range of 47-65 m2 g-1 and initially has a crystallite size that is of the order of 10 nm. A further increase in temperature, however, causes the particles to coarsen to over 25 nm in diameter. In principle, the coarsening phenomenon may be interrupted to control the particle size.

  20. Caramel popcorn shaped silicon particle with carbon coating as a high performance anode material for Li-ion batteries.

    PubMed

    He, Meinan; Sa, Qina; Liu, Gao; Wang, Yan

    2013-11-13

    Silicon is a very promising anode material for lithium ion batteries. It has a 4200 mAh/g theoretical capacity, which is ten times higher than that of commercial graphite anodes. However, when lithium ions diffuse to Si anodes, the volume of Si will expand to almost 400% of its initial size and lead to the crack of Si. Such a huge volume change and crack cause significant capacity loss. Meanwhile, with the crack of Si particles, the conductivity between the electrode and the current collector drops. Moreover, the solid electrolyte interphase (SEI), which is generated during the cycling, reduces the discharge capacity. These issues must be addressed for widespread application of this material. In this work, caramel popcorn shaped porous silicon particles with carbon coating are fabricated by a set of simple chemical methods as active anode material. Si particles are etched to form a porous structure. The pores in Si provide space for the volume expansion and liquid electrolyte diffusion. A layer of amorphous carbon is formed inside the pores, which gives an excellent isolation between the Si particle and electrolyte, so that the formation of the SEI layer is stabilized. Meanwhile, this novel structure enhances the mechanical properties of the Si particles, and the crack phenomenon caused by the volume change is significantly restrained. Therefore, an excellent cycle life under a high rate for the novel Si electrode is achieved.

  1. Impact of carbon, oxygen and sulfur content of microscale zerovalent iron particles on its reactivity towards chlorinated aliphatic hydrocarbons.

    PubMed

    Velimirovic, Milica; Larsson, Per-Olof; Simons, Queenie; Bastiaens, Leen

    2013-11-01

    Zerovalent iron (ZVI) abiotically degrades several chlorinated aliphatic hydrocarbons (CAHs) via reductive dechlorination, which offers perspectives for in situ groundwater remediation applications. The difference in reactivity between ZVI particles is often linked with their specific surface area. However, other parameters may influence the reactivity as well. Earlier, we reported for a set of microscale zerovalent iron (mZVI) particles the disappearance kinetic of different CAHs which were collected under consistent experimental conditions. In the present study, these kinetic data were correlated with the carbon, oxygen and sulfur content of mZVI particles. It was confirmed that not only the specific surface area affects the disappearance kinetic of CAHs, but also the chemical composition of the mZVI particles. The chemical composition, in addition, influences CAHs removal mechanism inducing sorption onto mZVI particles instead of dechlorination. Generally, high disappearance kinetic of CAHs was observed for particles containing less oxygen. A high carbon content, on the other hand, induced nonreactive sorption of the contaminants on the mZVI particles. To obtain efficient remediation of CAHs by mZVI particles, this study suggested that the carbon and oxygen content should not exceed 0.5% and 1% respectively. Finally, the efficiency of the mZVI particles may be improved to some extent by enriching them with sulfur. However, the impact of sulfur content on the reactivity of mZVI particles is less pronounced than that of the carbon and oxygen content. Copyright © 2013 Elsevier Ltd. All rights reserved.

  2. Active Brownian particles with velocity-alignment and active fluctuations

    NASA Astrophysics Data System (ADS)

    Großmann, R.; Schimansky-Geier, L.; Romanczuk, P.

    2012-07-01

    We consider a model of active Brownian particles (ABPs) with velocity alignment in two spatial dimensions with passive and active fluctuations. Here, active fluctuations refers to purely non-equilibrium stochastic forces correlated with the heading of an individual active particle. In the simplest case studied here, they are assumed to be independent stochastic forces parallel (speed noise) and perpendicular (angular noise) to the velocity of the particle. On the other hand, passive fluctuations are defined by a noise vector independent of the direction of motion of a particle, and may account, for example, for thermal fluctuations. We derive a macroscopic description of the ABP gas with velocity-alignment interaction. Here, we start from the individual-based description in terms of stochastic differential equations (Langevin equations) and derive equations of motion for the coarse-grained kinetic variables (density, velocity and temperature) via a moment expansion of the corresponding probability density function. We focus here on the different impact of active and passive fluctuations on onset of collective motion and show how active fluctuations in the active Brownian dynamics can change the phase-transition behaviour of the system. In particular, we show that active angular fluctuations lead to an earlier breakdown of collective motion and to the emergence of a new bistable regime in the mean-field case.

  3. Measurement of Ultrafine Particles and Other Air Pollutants Emitted by Cooking Activities

    PubMed Central

    Zhang, Qunfang; Gangupomu, Roja H.; Ramirez, David; Zhu, Yifang

    2010-01-01

    Cooking emissions show a strong dependence on cooking styles and parameters. Measurements of the average ultrafine particle (UFP) concentration, PM2.5 and black carbon concentrations emitted by cooking activities ranged from 1.34 × 104 to 6.04 × 105 particles/cm3, 10.0 to 230.9 μg/m3 and 0.1 to 0.8 μg/m3, respectively. Lower UFP concentrations were observed during boiling, while higher levels were emitted during frying. The highest UFP concentrations were observed when using a gas stove at high temperature with the kitchen exhaust fan turned off. The observed UFP profiles were similar in the kitchen and in another room, with a lag of approximately 10 min. PMID:20617057

  4. Embedded Carbide-derived Carbon (CDC) particles in polypyrrole (PPy) for linear actuator

    NASA Astrophysics Data System (ADS)

    Zondaka, Zane; Valner, Robert; Aabloo, Alvo; Tamm, Tarmo; Kiefer, Rudolf

    2016-04-01

    Conducting polymer linear actuators, for example sodium dodecylbenzenesulfonate (NaDBS) doped polypyrrole (PPy/DBS), have shown moderate strain and stress. The goal of this work was to increase the obtainable strain and stress by adding additional active material to PPy/DBS. In recent year's carbide-derived carbon (CDC)-based materials have been applied in actuators; however, the obtained displacement and actuation speed has been low comparing to conducting polymer based actuators. In the present work, a CDC-PPy hybrid was synthesized electrochemically and polyoxometalate (POM) - phosphotungstic acid - was used to attach charge to CDC particles. The CDC-POM served in the presence of NaDBS as an additional electrolyte. Cyclic voltammetry and chronopotentiometric electrochemomechanical deformation (ECMD) measurements were performed in Lithium bis(trifluoromethanesulfonyl)- imide (LiTFSI) aqueous electrolyte. The ECMD measurements revealed that the hybrid CDC-PPy material exhibited higher force and strain in comparison to PPy/DBS films. The new material was investigated by scanning electron microscopy (SEM) to evaluate CDC particle embedding in the polymer network.

  5. Decomposition and particle release of a carbon nanotube/epoxy nanocomposite at elevated temperatures

    NASA Astrophysics Data System (ADS)

    Schlagenhauf, Lukas; Kuo, Yu-Ying; Bahk, Yeon Kyoung; Nüesch, Frank; Wang, Jing

    2015-11-01

    Carbon nanotubes (CNTs) as fillers in nanocomposites have attracted significant attention, and one of the applications is to use the CNTs as flame retardants. For such nanocomposites, possible release of CNTs at elevated temperatures after decomposition of the polymer matrix poses potential health threats. We investigated the airborne particle release from a decomposing multi-walled carbon nanotube (MWCNT)/epoxy nanocomposite in order to measure a possible release of MWCNTs. An experimental set-up was established that allows decomposing the samples in a furnace by exposure to increasing temperatures at a constant heating rate and under ambient air or nitrogen atmosphere. The particle analysis was performed by aerosol measurement devices and by transmission electron microscopy (TEM) of collected particles. Further, by the application of a thermal denuder, it was also possible to measure non-volatile particles only. Characterization of the tested samples and the decomposition kinetics were determined by the usage of thermogravimetric analysis (TGA). The particle release of different samples was investigated, of a neat epoxy, nanocomposites with 0.1 and 1 wt% MWCNTs, and nanocomposites with functionalized MWCNTs. The results showed that the added MWCNTs had little effect on the decomposition kinetics of the investigated samples, but the weight of the remaining residues after decomposition was influenced significantly. The measurements with decomposition in different atmospheres showed a release of a higher number of particles at temperatures below 300 °C when air was used. Analysis of collected particles by TEM revealed that no detectable amount of MWCNTs was released, but micrometer-sized fibrous particles were collected.

  6. The Contribution of Black Carbon to Ice Nucleating Particle Concentrations from Prescribed Burns and Wildfires

    NASA Astrophysics Data System (ADS)

    Schill, G. P.; DeMott, P. J.; Suski, K. J.; Emerson, E. W.; Rauker, A. M.; Kodros, J.; Levin, E. J.; Hill, T. C. J.; Farmer, D.; Pierce, J. R.; Kreidenweis, S. M.

    2017-12-01

    Black carbon (BC) has been implicated as a potential immersion-mode ice nucleating particle (INP) because of its relative abundance in the upper troposphere. Furthermore, several field and aircraft measurements have observed positive correlations between BC and INP concentrations. Despite this, the efficiency of BC to act as an immersion-mode INP is poorly constrained. Indeed, previous results from laboratory studies are in conflict, with estimates of BC's impact on INP ranging from no impact to being efficient enough to rival the well-known INP mineral dust. It is, however, becoming clear that the ice nucleation activity of BC may depend on both its fuel type and combustion conditions. For example, previous work has shown that diesel exhaust BC is an extremely poor immersion-mode INP, but laboratory burns of biomass fuels indicate that BC can contribute up to 70% of all INP for some fuel types. Given these dependencies, we propose that sampling from real-world biomass burning sources would provide the most useful new information on the contribution of BC to atmospheric INP. In this work, we will present recent results looking at the sources of INP from prescribed burns and wildfires. To determine the specific contribution of refractory black carbon (rBC) to INP concentrations, we utilized a new technique that couples the Single Particle Soot Photometer (SP2) to the Colorado State University Continuous Flow Diffusion Chamber (CFDC). The SP2 utilizes laser-induced incandescence to quantify rBC mass on a particle-by-particle basis; in doing so, it also selectively destroys rBC particles by heating them to their vaporization temperature. Thus, the SP2 can be used as a selective pre-filter for rBC into the CFDC. Furthermore, we have also used a filter-based technique for measuring INP, the Ice Spectrometer, which can employ pretreatments such as heating and digestion by H2O2 to determine the contribution of heat-labile and organic particles, respectively.

  7. CO2, NOx, and particle emissions from aircraft and support activities at a regional airport.

    PubMed

    Klapmeyer, Michael E; Marr, Linsey C

    2012-10-16

    The goal of this research was to quantify emissions of carbon dioxide (CO(2)), nitrogen oxides (NO(x)), particle number, and black carbon (BC) from in-use aircraft and related activity at a regional airport. Pollutant concentrations were measured adjacent to the airfield and passenger terminal at the Roanoke Regional Airport in Virginia. Observed NO(x) emission indices (EIs) for jet-powered, commuter aircraft were generally lower than those contained in the International Civil Aviation Organization databank for both taxi (same as idle) and takeoff engine settings. NO(x) EIs ranged from 1.9 to 3.7 g (kg fuel)(-1) across five types of aircraft during taxiing, whereas EIs were consistently higher, 8.8-20.6 g (kg fuel)(-1), during takeoff. Particle number EIs ranged from 1.4 × 10(16) to 7.1 × 10(16) (kg fuel)(-1) and were slightly higher in taxi mode than in takeoff mode for four of the five types of aircraft. Diurnal patterns in CO(2) and NO(x) concentrations were influenced mainly by atmospheric conditions, while patterns in particle number concentrations were attributable mainly to patterns in aircraft activity. CO(2) and NO(x) fluxes measured by eddy covariance were higher at the terminal than at the airfield and were lower than found in urban areas.

  8. The synthesis of carbon electrode supercapacitor from durian shell based on variations in the activation time

    NASA Astrophysics Data System (ADS)

    Taer, E.; Dewi, P.; Sugianto, Syech, R.; Taslim, R.; Salomo, Susanti, Y.; Purnama, A.; Apriwandi, Agustino, Setiadi, R. N.

    2018-02-01

    The synthesis of carbon electrode from durian shell based on variations in the activation time has been carried out. Synthesis of carbon electrode was started by a carbonization process at a temperature of 600°C in nitrogen gas and then followed by physical activation process using water vapor at a temperature of 900°C by varying time of 1, 2 and 3 h. All of the variations of the samples were chemically activated using an activator of ZnCl2 with a concentration of 0.4 M. The physical properties such as density, surface morphology, degree of crystallinity and elemental content were analyzed. Moreover, the electrochemical properties such as specific capacitance of supercapacitor cells were studied using Cyclic Voltammetry methods. The density, stack height and carbon content were increased as activation time increases, while the specific capacitance of the supercapacitor cell decreases against the increase of activation time. Specific capacitances for 1, 2 and 3 h activation time are 88.39 F/g, 80.08 F/g and 74.61 F/g, respectively. Based on the surface morphology study it was shown that the increased in activation time causes narrowing of the pores between particles.

  9. Anchorage of iron hydro(oxide) nanoparticles onto activated carbon to remove As(V) from water.

    PubMed

    Nieto-Delgado, Cesar; Rangel-Mendez, Jose Rene

    2012-06-01

    The adsorption of arsenic (V) by granular iron hydro(oxides) has been proven to be a reliable technique. However, due to the low mechanical properties of this material, it is difficult to apply it in full scale water treatment. Hence, the aim of this research is to develop a methodology to anchor iron hydro(oxide) nanoparticles onto activated carbon, in which the iron hydro(oxide) nanoparticles will give the activated carbon an elevated active surface area for arsenic adsorption and also help avoid the blockage of the activated carbon pores. Three activated carbons were modified by employing the thermal hydrolysis of iron as the anchorage procedure. The effects of hydrolysis temperature (60-120 °C), hydrolysis time (4-16 h), and FeCl(3) concentration (0.4-3 mol Fe/L) were studied by the surface response methodology. The iron content of the modified samples ranged from 0.73 to 5.27%, with the higher end of the range pertaining to the carbons with high oxygen content. The materials containing smaller iron hydro(oxide) particles exhibited an enhanced arsenic adsorption capacity. The best adsorbent material reported an arsenic adsorption capacity of 4.56 mg As/g at 1.5 ppm As at equilibrium and pH 7. Copyright © 2012 Elsevier Ltd. All rights reserved.

  10. Inflammatory response against different carbon fiber-reinforced PEEK wear particles compared with UHMWPE in vivo.

    PubMed

    Utzschneider, Sandra; Becker, Fabian; Grupp, Thomas M; Sievers, Birte; Paulus, Alexander; Gottschalk, Oliver; Jansson, Volkmar

    2010-11-01

    Poly(ether ether ketone) (PEEK) and its composites are recognized as alternative bearing materials for use in arthroplasty because of their mechanical properties. The objective of this project was to evaluate the biological response of two different kinds of carbon fiber-reinforced (CFR) PEEK compared with ultra-high molecular weight polyethylene (UHMWPE) in vivo as a standard bearing material. Wear particles of the particulate biomaterials were injected into the left knee joint of female BALB/c mice. Assessment of the synovial microcirculation using intravital fluorescence microscopy as well as histological evaluation of the synovial layer were performed 7 days after particle injection. Enhanced leukocyte-endothelial cell interactions and an increase in functional capillary density as well as histological investigations revealed that all tested biomaterials caused significantly (P < 0.05) increased inflammatory reactions compared with control animals (injected with sterile phosphate-buffered saline), without any difference between the tested biomaterials (P > 0.05). These data suggest that wear debris of CFR-PEEK is comparable with UHMWPE in its biological activity. Therefore, CFR-PEEK represents an alternative bearing material because of its superior mechanical and chemical behavior without any increased biological activity of the wear particles, compared with a standard bearing material. Copyright © 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  11. Kinetic study of Chromium VI adsorption onto palm kernel shell activated carbon

    NASA Astrophysics Data System (ADS)

    Mohammad, Masita; Sadeghi Louyeh, Shiva; Yaakob, Zahira

    2018-04-01

    Heavy metal contamination of industrial effluent is one of the significant environmental problems due to their toxicity and its accumulation throughout the food chain. Adsorption is one of the promising methods for removal of heavy metals from aqua solution because of its simple technique, efficient, reliable and low-cost due to the utilization of residue from the agricultural industry. In this study, activated carbon from palm kernel shells has been produced through chemical activation process using zinc chloride as an activating agent and carbonized at 800 °C. Palm kernel shell activated carbon, PAC was assessed for its efficiency to remove Chromium (VI) ions from aqueous solutions through a batch adsorption process. The kinetic mechanisms have been analysed using Lagergren first-order kinetics model, second-order kinetics model and intra-particle diffusion model. The characterizations such as BET surface area, surface morphology, SEM-EDX have been done. The result shows that the activation process by ZnCl2 was successfully improved the porosity and modified the functional group of palm kernel shell. The result shows that the maximum adsorption capacity of Cr is 11.40mg/g at 30ppm initial metal ion concentration and 0.1g/50mL of adsorbent concentration. The adsorption process followed the pseudo second orders kinetic model.

  12. Photocurrent spectroscopy of exciton and free particle optical transitions in suspended carbon nanotube pn-junctions

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Chang, Shun-Wen; Theiss, Jesse; Hazra, Jubin

    2015-08-03

    We study photocurrent generation in individual, suspended carbon nanotube pn-junction diodes formed by electrostatic doping using two gate electrodes. Photocurrent spectra collected under various electrostatic doping concentrations reveal distinctive behaviors for free particle optical transitions and excitonic transitions. In particular, the photocurrent generated by excitonic transitions exhibits a strong gate doping dependence, while that of the free particle transitions is gate independent. Here, the built-in potential of the pn-junction is required to separate the strongly bound electron-hole pairs of the excitons, while free particle excitations do not require this field-assisted charge separation. We observe a sharp, well defined E{sub 11}more » free particle interband transition in contrast with previous photocurrent studies. Several steps are taken to ensure that the active charge separating region of these pn-junctions is suspended off the substrate in a suspended region that is substantially longer than the exciton diffusion length and, therefore, the photocurrent does not originate from a Schottky junction. We present a detailed model of the built-in fields in these pn-junctions, which, together with phonon-assistant exciton dissociation, predicts photocurrents on the same order of those observed experimentally.« less

  13. CARDIOVASCULAR RESPONSES IN UNRESTRAINED WKY-RATS TO INHALED ULTRAFINE CARBON PARTICLES

    EPA Science Inventory

    Abstract
    This study provides evidence for adverse cardiac effects of inhaled ultrafine particles (UFPs) in healthy WKY rats. Short term exposure (24 h) with carbon UFPs (180 ?g?m ?) induced a moderate but significant heart rate increase of 18 bpm (4.8 %) in association with a ...

  14. Development of biomass in a drinking water granular active carbon (GAC) filter.

    PubMed

    Velten, Silvana; Boller, Markus; Köster, Oliver; Helbing, Jakob; Weilenmann, Hans-Ulrich; Hammes, Frederik

    2011-12-01

    Indigenous bacteria are essential for the performance of drinking water biofilters, yet this biological component remains poorly characterized. In the present study we followed biofilm formation and development in a granular activated carbon (GAC) filter on pilot-scale during the first six months of operation. GAC particles were sampled from four different depths (10, 45, 80 and 115 cm) and attached biomass was measured with adenosine tri-phosphate (ATP) analysis. The attached biomass accumulated rapidly on the GAC particles throughout all levels in the filter during the first 90 days of operation and maintained a steady state afterward. Vertical gradients of biomass density and growth rates were observed during start-up and also in steady state. During steady state, biomass concentrations ranged between 0.8-1.83 x 10(-6) g ATP/g GAC in the filter, and 22% of the influent dissolved organic carbon (DOC) was removed. Concomitant biomass production was about 1.8 × 10(12) cells/m(2)h, which represents a yield of 1.26 × 10(6) cells/μg. The bacteria assimilated only about 3% of the removed carbon as biomass. At one point during the operational period, a natural 5-fold increase in the influent phytoplankton concentration occurred. As a result, influent assimilable organic carbon concentrations increased and suspended bacteria in the filter effluent increased 3-fold as the direct consequence of increased growth in the biofilter. This study shows that the combination of different analytical methods allows detailed quantification of the microbiological activity in drinking water biofilters. Copyright © 2011 Elsevier Ltd. All rights reserved.

  15. Structural and adsorptive properties of activated carbons prepared by carbonization and activation of resins.

    PubMed

    Leboda, R; Skubiszewska-Zieba, J; Tomaszewski, W; Gun'ko, V M

    2003-07-15

    Four activated carbons (S1-S4) possessing different structural characteristics were prepared by carbonization of commercial resins (used for ion exchange) and subsequent activation. Their textural parameters were determined on the basis of nitrogen adsorption-desorption at 77.4 K, analyzed by applying several local and overall adsorption isotherm equations. The nature of carbon surface functionalities was analyzed by FTIR spectroscopy. The GC and solid-phase extraction (SPE) techniques were applied to study the influence of the texture of carbonaceous materials on their adsorptive properties. The adsorption efficiency of synthesized carbons with respect to alkylhalides used as probe compounds in the GC measurements varied over a range from 28% (C(2)H(3)Cl(3)/S2) to 85% (CHBr(3)/S1) depending on the type of adsorbates and adsorbents. The concentrating efficiency of these carbons in SPE of explosive materials changed over a larger range from 12% (trinitroglycerin/S4) and 13% (trinitrotoluene/S2) up to 100% (octogen/S1). Active carbon prepared using Zerolite 225x8 as a precursor demonstrated better results than other carbons in two types of adsorption with average values of the efficiency of 75.4% for explosives and 60.8% for alkylhalides.

  16. Development and evaluation of antimicrobial activated carbon fiber filters using Sophora flavescens nanoparticles.

    PubMed

    Sim, Kyoung Mi; Kim, Kyung Hwan; Hwang, Gi Byoung; Seo, SungChul; Bae, Gwi-Nam; Jung, Jae Hee

    2014-09-15

    Activated carbon fiber (ACF) filters have a wide range of applications, including air purification, dehumidification, and water purification, due to their large specific surface area, high adsorption capacity and rate, and specific surface reactivity. However, when airborne microorganisms such as bacteria and fungi adhere to the carbon substrate, ACF filters can become a source of microbial contamination, and their filter efficacy declines. Antimicrobial treatments are a promising means of preventing ACF bio-contamination. In this study, we demonstrate the use of Sophora flavescens in antimicrobial nanoparticles coated onto ACF filters. The particles were prepared using an aerosol process consisting of nebulization-thermal drying and particle deposition. The extract from S. flavescens is an effective, natural antimicrobial agent that exhibits antibacterial activity against various pathogens. The efficiency of Staphylococcus epidermidis inactivation increased with the concentration of S. flavescens nanoparticles in the ACF filter coating. The gas adsorption efficiency of the coated antimicrobial ACF filters was also evaluated using toluene. The toluene-removal capacity of the ACF filters remained unchanged while the antimicrobial activity was over 90% for some nanoparticle concentrations. Our results provide a scientific basis for controlling both bioaerosol and gaseous pollutants using antimicrobial ACF filters coated with S. flavescens nanoparticles. Copyright © 2014 Elsevier B.V. All rights reserved.

  17. Collective rotations of active particles interacting with obstacles

    NASA Astrophysics Data System (ADS)

    Mokhtari, Zahra; Aspelmeier, Timo; Zippelius, Annette

    2017-10-01

    We consider active particles in a heterogeneous medium, modeled by static, random obstacles. In accordance with the known tendency of active particles to cluster, we observe accumulation and crystallization of active particles around the obstacles which serve as nucleation sites. In the limit of high activity, the crystals start to rotate spontaneously, resembling a rotating rigid body. We trace the occurrence of these oscillations to the enhanced attraction of particles whose orientation points along the rotational velocity as compared to those whose orientation points in the opposite direction.

  18. Effect of Discharge Rate on Positive Active Material of Lead Carbon Battery for Energy Storage

    NASA Astrophysics Data System (ADS)

    Chen, Kailun; Liu, Hao; Hu, Chen; Gao, Fei; Yang, Kai; Wang, Hao

    2017-10-01

    Lead carbon battery has been widespread concern with its excellent performance of charge and discharge under High Rate Part State of Charge (HRPSoC) as well as its cycle performance. In this paper, the cycling performance of lead carbon battery for energy storage was tested by different discharge rate. The effects of different discharge rate on the composition and morphology of positive active materials in the cycle was studied by XRD and SEM. The effect of different discharge rate on the ohmic impedance of lead carbon battery was studied by testing Electrochemical Impedance Spectroscopy with different capacity retention rates. The results show that with the increase of the discharge rate, the content of PbO2 in the positive active material increases, the active substance utilization and the particle size of PbO2 crystal declines, and the ohmic impedance of the battery decreases.

  19. Use of stable carbon and nitrogen isotope ratios in size segregated aerosol particles for the O/I penetration evaluation

    NASA Astrophysics Data System (ADS)

    Garbaras, Andrius; Garbariene, Inga; Masalaite, Agne; Ceburnis, Darius; Krugly, Edvinas; Kvietkus, Kestutis; Remeikis, Vidmantas; Martuzevicius, Dainius

    2015-04-01

    particles penetrates from outside to inside. Observed isotope ratio depletion indicates that information about aerosol sources can be lost if measurements are performed only inside house. Using carbon and nitrogen isotope ratios data set, we were able to identify and distinguish main aerosol sources (traffic, heating activities) and penetration of aerosol particles from outdoor to indoor. Acknowledgment This work was supported by Research Council of Lithuania under grant "Pollution Control in Biomass Combustion: from Pollutant Formation to Human Exposure" (BioMassPoll), Project no. ATE05/2012. EPA Ireland is acknowledged for the fellowship grant of D. Ceburnis 1. Garbaras, A. Masalaite, I. Garbariene, D. Ceburnis, E. Krugly V. Remeikis, E. Puida K. Kvietkus, D. Martuzevicius, Stable carbon fractionation in size-segregated aerosol particles produced by controlled biomass burning, Journal of Aerosol Science, Vol. 79, p. 86-96 (2015); 2. D. Ceburnis, A. Garbaras, S. Szidat, M. Rinaldi, S. Fahrni, N. Perron, L. Wacker, S. Leinert, V. Remeikis, M. C. Facchini, A. S. H. Prevot, S. G. Jennings, and C. D. O'Dowd, Quantification of the carbonaceous matter origin in submicron marine aerosol particles by dual carbon isotope analysis, Atmospheric Chemistry and Physics, Vol 11, pp. 8593-8606 (2011); 3. V. Ulevicius, S. Bycenkiene, V. Remeikis, A. Garbaras, S. Kecorius, J. Andriejauskiene, D. Jasineviciene, G. Mocnik, Characterization of pollution events in the East Baltic region affected by regional biomass fire emissions, Atmospheric Research, Vol. 98 (2-4), pp. 190-200 (2010).

  20. Preliminary study on preparation of BCNO phosphor particles using citric acid as carbon source

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Nuryadin, Bebeh W.; Pratiwi, Tripuspita; Faryuni, Irfana D.

    A citric acid was used as a carbon source in the preparation of boron carbon oxy-nitride (BCNO) phosphor particles by a facile process. The preparation process was conducted at relatively low temperature 750 °C and at ambient pressure. The prepared BCNO phosphors showed a high photoluminescence (PL) performance at peak emission wavelength of 470 nm under excitation by a UV light 365 nm. The effects of carbon/boron and nitrogen/boron molar ratios on the PL properties were also investigated. The result showed that the emission spectra with a wavelength peak ranging from 444 nm to 496 nm can be obtained bymore » varying carbon/boron ratios from 0.1 to 0.9. In addition, the observations showed that the BCNO phosphor material has two excitation peaks located at the 365 nm (UV) and 420 nm (blue). Based on these observations, we believe that the citric acid derived BCNO phosphor particles can be a promising inexpensive material for phosphor conversion-based white LED.« less

  1. Study of static and dynamic magnetic properties of Fe nanoparticles composited with activated carbon

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Pal, Satyendra Prakash, E-mail: sppal85@gmail.com; Department of Physical Sciences, Indian Institute of Science Education and Research, Mohali, Knowledge city, Sector81, SAS Nagar, Manauli-140306, Punjab; Kaur, Guratinder

    2016-05-23

    Nanocomposite of Fe nanoparticles with activated carbon has been synthesized to alter the magnetic spin-spin interaction and hence study the dilution effect on the static and dynamic magnetic properties of the Fe nanoparticle system. Transmission electron microscopic (TEM) image shows the spherical Fe nanoparticles dispersed in carbon matrix with 13.8 nm particle size. Temperature dependent magnetization measurement does not show any blocking temperature at all, right up to the room temperature. Magnetic hysteresis curve, taken at 300 K, shows small value of the coercivity and this small hysteresis indicates the presence of an energy barrier and inherent magnetization dynamics. Langevinmore » function fitting of the hysteresis curve gives almost similar value of particle size as obtained from TEM analysis. Magnetic relaxation data, taken at a temperature of 100 K, were fitted with a combination of two exponentially decaying function. This diluted form of nanoparticle system, which has particles size in the superparamagnetic limit, behaves like a dilute ensemble of superspins with large value of the magnetic anisotropic barrier.« less

  2. Bimetallic Cu-Ni nanoparticles supported on activated carbon for catalytic oxidation of benzyl alcohol

    NASA Astrophysics Data System (ADS)

    Kimi, Melody; Jaidie, Mohd Muazmil Hadi; Pang, Suh Cem

    2018-01-01

    A series of bimetallic copper-nickel (CuNix, x = 0.1, 0.2, 0.5 and 1) nanoparticles supported on activated carbon (AC) were prepared by deposition-precipitation method for the oxidation of benzyl alcohol to benzaldehyde using hydrogen peroxide as oxidising agent. Analyses by means of X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) confirmed that Cu and Ni was successfully added on the surface of activated carbon. CuNi1/AC showed the best catalytic activity for the oxidation of benzyl alcohols to the corresponding aldehyde within a short reaction period at 80 °C. The catalytic performance is significantly enhanced by the addition of equal amount of Ni as compared to the monometallic counterpart. This result indicates the synergistic effect between Ni and Cu particles in the catalytic oxidation reaction.

  3. Advanced biological activated carbon filter for removing pharmaceutically active compounds from treated wastewater.

    PubMed

    Sbardella, Luca; Comas, Joaquim; Fenu, Alessio; Rodriguez-Roda, Ignasi; Weemaes, Marjoleine

    2018-04-28

    Through their release of effluents, conventional wastewater treatment plants (WWTPs) represent a major pollution point sources for pharmaceutically active compounds (PhACs) in water bodies. The combination of a biological activated carbon (BAC) filter coupled with an ultrafiltration (UF) unit was evaluated as an advanced treatment for PhACs removal at pilot scale. The BAC-UF pilot plant was monitored for one year. The biological activity of the biofilm that developed on the granular activated carbon (GAC) particles and the contribution of this biofilm to the overall removal of PhACs were evaluated. Two different phases were observed during the long-term monitoring of PhACs removal. During the first 9200 bed volumes (BV; i.e., before GAC saturation), 89, 78, 83 and 79% of beta-blockers, psychiatric drugs, antibiotics and a mix of other therapeutic groups were removed, respectively. The second phase was characterized by deterioration of the overall performances during the period between 9200 and 13,800 BV. To quantify the respective contribution of adsorption and biodegradation, a lab-scale setup was operated for four months and highlighted the essential role played by GAC in biofiltration units. Physical adsorption was indeed the main removal mechanism. Nevertheless, a significant contribution due to biological activity was detected for some PhACs. The biofilm contributed to the removal of 22, 25, 30, 32 and 35% of ciprofloxacin, bezafibrate, ofloxacin, azithromycin and sulfamethoxazole, respectively. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.

  4. Linear response approach to active Brownian particles in time-varying activity fields

    NASA Astrophysics Data System (ADS)

    Merlitz, Holger; Vuijk, Hidde D.; Brader, Joseph; Sharma, Abhinav; Sommer, Jens-Uwe

    2018-05-01

    In a theoretical and simulation study, active Brownian particles (ABPs) in three-dimensional bulk systems are exposed to time-varying sinusoidal activity waves that are running through the system. A linear response (Green-Kubo) formalism is applied to derive fully analytical expressions for the torque-free polarization profiles of non-interacting particles. The activity waves induce fluxes that strongly depend on the particle size and may be employed to de-mix mixtures of ABPs or to drive the particles into selected areas of the system. Three-dimensional Langevin dynamics simulations are carried out to verify the accuracy of the linear response formalism, which is shown to work best when the particles are small (i.e., highly Brownian) or operating at low activity levels.

  5. Solid Particle Erosion Behaviors of Carbon-Fiber Epoxy Composite and Pure Titanium

    NASA Astrophysics Data System (ADS)

    Cai, Feng; Gao, Feng; Pant, Shashank; Huang, Xiao; Yang, Qi

    2016-01-01

    Rotor blades of Bell CH-146 Griffon helicopter experience excessive solid particle erosion at low altitudes in desert environment. The rotor blade is made of an advanced light-weight composite which, however, has a low resistance to solid particle erosion. Coatings have been developed and applied to protect the composite blade. However, due to the influence of coating process on composite material, the compatibility between coating and composite base, and the challenges of repairing damaged coatings as well as the inconsistency between the old and new coatings, replaceable thin metal shielding is an alternative approach; and titanium, due to its high-specific strength and better formability, is an ideal candidate. This work investigates solid particle erosion behaviors of carbon-fiber epoxy composite and titanium in order to assess the feasibility of titanium as a viable candidate for erosion shielding. Experiment results showed that carbon-fiber epoxy composite showed a brittle erosion behavior, whereas titanium showed a ductile erosion mode. The erosion rate on composite was 1.5 times of that on titanium at impingement angle 15° and increased to 5 times at impact angle 90°.

  6. Effects of specific surface area of metallic nickel particles on carbon deposition kinetics

    NASA Astrophysics Data System (ADS)

    Chen, Zhi-yuan; Bian, Liu-zhen; Yu, Zi-you; Wang, Li-jun; Li, Fu-shen; Chou, Kuo-Chih

    2018-02-01

    Carbon deposition on nickel powders in methane involves three stages in different reaction temperature ranges. Temperature programing oxidation test and Raman spectrum results indicated the formation of complex and ordered carbon structures at high deposition temperatures. The values of I(D)/ I(G) of the deposited carbon reached 1.86, 1.30, and 1.22 in the first, second, and third stages, respectively. The structure of carbon in the second stage was similar to that in the third stage. Carbon deposited in the first stage rarely contained homogeneous pyrolytic deposit layers. A kinetic model was developed to analyze the carbon deposition behavior in the first stage. The rate-determining step of the first stage is supposed to be interfacial reaction. Based on the investigation of carbon deposition kinetics on nickel powders from different resources, carbon deposition rate is suggested to have a linear relation with the square of specific surface area of nickel particles.

  7. Biological activation of carbon filters.

    PubMed

    Seredyńska-Sobecka, Bozena; Tomaszewska, Maria; Janus, Magdalena; Morawski, Antoni W

    2006-01-01

    To prepare biological activated carbon (BAC), raw surface water was circulated through granular activated carbon (GAC) beds. Biological activity of carbon filters was initiated after about 6 months of filter operation and was confirmed by two methods: measurement of the amount of biomass attached to the carbon and by the fluorescein diacetate (FDA) test. The effect of carbon pre-washing on WG-12 carbon properties was also studied. For this purpose, the nitrogen adsorption isotherms at 77K and Fourier transform-infrared (FT-IR) spectra analyses were performed. Moreover, iodine number, decolorizing power and adsorption properties of carbon in relation to phenol were studied. Analysis of the results revealed that after WG-12 carbon pre-washing its BET surface increased a little, the pH value of the carbon water extract decreased from 11.0 to 9.4, decolorizing power remained at the same level, and the iodine number and phenol adsorption rate increased. In preliminary studies of the ozonation-biofiltration process, a model phenol solution with concentration of approximately 10mg/l was applied. During the ozonation process a dose of 1.64 mg O(3)/mg TOC (total organic carbon) was employed and the contact time was 5 min. Four empty bed contact times (EBCTs) in the range of 2.4-24.0 min were used in the biofiltration experiment. The effectiveness of purification was measured by the following parameters: chemical oxygen demand (COD(Mn)), TOC, phenol concentration and UV(254)-absorbance. The parameters were found to decrease with EBCT.

  8. Preparation of nitrogen-doped graphene/activated carbon composite papers to enhance energy storage in supercapacitors

    NASA Astrophysics Data System (ADS)

    Li, Yong-feng; Liu, Yan-zhen; Liang, Yu; Guo, Xiao-hui; Chen, Cheng-meng

    2017-09-01

    This report presents a facile and effective method to synthesize freestanding nitrogen-doped reduced graphene oxide (rGO)/activated carbon (AC) composite papers for supercapacitors by a method combining vacuum filtration with post-annealing in NH3 atmosphere. The effect of activated carbon contents on the microstructure and capacitive behavior of the resulting composite papers before and after the annealing was investigated by X-ray diffraction, scanning electron microscopy, and Raman and X-ray photoelectron spectroscopy. Results show that the composite paper with a 30% activated carbon loading has a high nitrogen content of 14.6 at% and superior capacitive performance (308 F/g, 1 A/g) to the other composite papers with various activated carbon loadings. Nitrogen was doped and GO reduced during the annealing. The rGO nanosheets acted as a framework, and the AC particles served as spacers to avoid agglomeration of graphene sheets. The high capacitance of the composite paper is ascribed to the electric double-layer behavior and the reversible redox reactions of the nitrogen and oxygen groups. The entire process is simple, environmental friendly and easily scalable for mass production.

  9. SIGNALING MECHANISMS IN HUMAN AIRWAY EPITHELIAL CELLS EXPOSED TO CARBON ULTRAFINE PARTICLES

    EPA Science Inventory

    SIGNALING MECHANISMS IN HUMAN AIRWAY EPITHELIAL CELLS EXPOSED TO CARBON ULTRAFINE PARTICLES
    Y.M. Kim, A.G. Lenz, R. Silbajoris, I. Jaspers and J.M. Samet. Department of Environmental Sciences and Engineering and Center for Environmental Medicine, University of North Carolina, ...

  10. Self-supporting activated carbon/carbon nanotube/reduced graphene oxide flexible electrode for high performance supercapacitor

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Li, Xing; Tang, Yao; Song, Junhua

    A self-supporting and flexible activated carbon/carbon nanotube/reduced graphene oxide (AC/CNT/RGO) film has been rationally designed for constructing high-performance supercapacitor. We prepared the AC/CNT/RGO film by anchoring the AC particles with a 3D and porous framework built by hierarchically weaving the 1 D CNT and 2D RGO using their intrinsic van der Waals force. The CNT network is beneficial for improving the electronic conductivity of the electrode, while the AC particles could effectively suppress the aggregation of RGO and CNT due to their blocking effect. The synergistic effects among the AC, CNT and RGO validate the AC/CNT/RGO as a promising electrodemore » for supercapacitor, exhibiting greatly enhanced electrochemical performances in comparison with the pure RGO film, pure CNT film and AC electrode. Furthermore, the AC/CNT/RGO electrode delivers a high specific capacitance of 101 F g -1 at the current density of 0.2 A g -1 offering a maximum energy density of 30.0 W h kg -1 in organic electrolyte at the cut-off voltage range of 0.001–3.0 V. The findings of this work open a new avenue for the design of self-supporting electrodes for the development of flexible and light weight energy storage supercapacitor.« less

  11. Self-supporting activated carbon/carbon nanotube/reduced graphene oxide flexible electrode for high performance supercapacitor

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Li, Xing; Tang, Yao; Song, Junhua

    A self-supporting and flexible activated carbon/carbon nanotube/reduced graphene oxide (AC/CNT/RGO) film has been rationally designed for constructing high- performance supercapacitor. The AC/CNT/RGO film is prepared by anchoring the AC particles with a 3D and porous framework built by hierarchically weaving the 1 D CNT and 2D RGO using their intrinsic van der Waals force. The CNT network is beneficial for improving the electronic conductivity of the electrode, while the AC particles could effectively suppress the aggregation of RGO and CNT due to their blocking effect. The synergistic effects among the AC, CNT and RGO validate the AC/CNT/RGO as a promisingmore » electrode for supercapacitor, exhibiting greatly enhanced electrochemical performances in comparison with the pure RGO film, pure CNT film and AC electrode. The AC/CNT/RGO electrode delivers a high specific capacitance of 101 F g-1 at the current density of 0.2 A g-1, offering a maximum energy density of 30.0 W h kg-1 in organic electrolyte at the cut-off voltage range of 0.001~3.0 V. The findings of this work open a new avenue for the design of self-supporting electrodes for the development of flexible and light weight energy storage supercapacitor.« less

  12. Self-supporting activated carbon/carbon nanotube/reduced graphene oxide flexible electrode for high performance supercapacitor

    DOE PAGES

    Li, Xing; Tang, Yao; Song, Junhua; ...

    2017-12-06

    A self-supporting and flexible activated carbon/carbon nanotube/reduced graphene oxide (AC/CNT/RGO) film has been rationally designed for constructing high-performance supercapacitor. We prepared the AC/CNT/RGO film by anchoring the AC particles with a 3D and porous framework built by hierarchically weaving the 1 D CNT and 2D RGO using their intrinsic van der Waals force. The CNT network is beneficial for improving the electronic conductivity of the electrode, while the AC particles could effectively suppress the aggregation of RGO and CNT due to their blocking effect. The synergistic effects among the AC, CNT and RGO validate the AC/CNT/RGO as a promising electrodemore » for supercapacitor, exhibiting greatly enhanced electrochemical performances in comparison with the pure RGO film, pure CNT film and AC electrode. Furthermore, the AC/CNT/RGO electrode delivers a high specific capacitance of 101 F g -1 at the current density of 0.2 A g -1 offering a maximum energy density of 30.0 W h kg -1 in organic electrolyte at the cut-off voltage range of 0.001–3.0 V. The findings of this work open a new avenue for the design of self-supporting electrodes for the development of flexible and light weight energy storage supercapacitor.« less

  13. Carbon nanotubes for stabilization of nanostructured lipid particles

    NASA Astrophysics Data System (ADS)

    Gaunt, Nicholas P.; Patil-Sen, Yogita; Baker, Matthew J.; Kulkarni, Chandrashekhar V.

    2014-12-01

    Carbon nanotubes (CNTs) are increasingly studied for innovative biotechnological applications particularly where they are combined with essential biological materials like lipids. Lipids have been used earlier for enhancing the dispersibility of CNTs in aqueous solutions. Here we report a novel application of CNTs for stabilization of internally self-assembled nanostructured lipid particles of 2-5 μm size. Single-walled (pristine) as well as -OH and -COOH functionalized multi-walled CNTs were employed to produce nanostructured emulsions which stayed stable for months and could be re-dispersed after complete dehydration. Concentrations of CNTs employed for stabilization were very low; moreover CNTs were well-decorated with lipid molecules. These features contribute towards reducing their toxicity and improving biocompatibility for biomedical and pharmaceutical applications. Our approach paves the way for future development of combination therapies employing both CNTs and nanostructured lipid self-assembly together as carriers of different drugs.Carbon nanotubes (CNTs) are increasingly studied for innovative biotechnological applications particularly where they are combined with essential biological materials like lipids. Lipids have been used earlier for enhancing the dispersibility of CNTs in aqueous solutions. Here we report a novel application of CNTs for stabilization of internally self-assembled nanostructured lipid particles of 2-5 μm size. Single-walled (pristine) as well as -OH and -COOH functionalized multi-walled CNTs were employed to produce nanostructured emulsions which stayed stable for months and could be re-dispersed after complete dehydration. Concentrations of CNTs employed for stabilization were very low; moreover CNTs were well-decorated with lipid molecules. These features contribute towards reducing their toxicity and improving biocompatibility for biomedical and pharmaceutical applications. Our approach paves the way for future development

  14. Global Civil Aviation Black Carbon Particle Mass and Number Emissions

    NASA Astrophysics Data System (ADS)

    Stettler, M. E. J.

    2015-12-01

    Black carbon (BC) is a product of incomplete combustion emitted by aircraft engines. In the atmosphere, BC particles strongly absorb incoming solar radiation and influence cloud formation processes leading to highly uncertain, but likely net positive warming of the earth's atmosphere. At cruise altitude, BC particle number emissions can influence the concentration of ice nuclei that can lead to contrail formation, with significant and highly uncertainty climate impacts. BC particles emitted by aircraft engines also degrade air quality in the vicinity of airports and globally. A significant contribution to the uncertainty in environmental impacts of aviation BC emissions is the uncertainty in emissions inventories. Previous work has shown that global aviation BC mass emissions are likely to have been underestimated by a factor of three. In this study, we present an updated global BC particle number inventory and evaluate parameters that contribute to uncertainty using global sensitivity analysis techniques. The method of calculating particle number from mass utilises a description of the mobility of fractal aggregates and uses the geometric mean diameter, geometric standard deviation, mass-mobility exponent, primary particle diameter and material density to relate the particle number concentration to the total mass concentration. Model results show good agreement with existing measurements of aircraft BC emissions at ground level and at cruise altitude. It is hoped that the results of this study can be applied to estimate direct and indirect climate impacts of aviation BC emissions in future studies.

  15. Activated carbon production from bagasse and banana stem at various times of carbonization

    NASA Astrophysics Data System (ADS)

    Misran, E.; Maulina, S.; Dina, S. F.; Nazar, A.; Harahap, S. A.

    2018-02-01

    The utilization of bagasse and banana stem as activated carbon precursors has been conducted. In this study, the dried samples were impregnated using phosphoric acid (H3PO4) solution as the activator at a ratio of sample to the activator (w/w) was 1:1. The impregnation was conducted at room temperature for 24 hours. The samples then carbonized at 400 °C for 30, 45 and 60 minutes and finally washed and dried to obtain the activated carbon. The research aimed to investigate the effects of time of carbonization on the characteristics of activated carbon produced from bagasse and banana stem. The result showed that yield of activated carbon was in the range of 40.03 - 46.73 % with a high content of carbon as high 90.33 %. The result of BET analysis showed that the highest surface area reached1130.465 m2/g.

  16. Adsorptive removal of sulfate from acid mine drainage by polypyrrole modified activated carbons: Effects of polypyrrole deposition protocols and activated carbon source.

    PubMed

    Hong, Siqi; Cannon, Fred S; Hou, Pin; Byrne, Tim; Nieto-Delgado, Cesar

    2017-10-01

    Polypyrrole modified activated carbon was used to remove sulfate from acid mine drainage water. The polypyrrole modified activated carbon created positively charged functionality that offered elevated sorption capacity for sulfate. The effects of the activated carbon type, approach of polymerization, preparation temperature, solvent, and concentration of oxidant solution over the sulfate adsorption capacity were studied at an array of initial sulfate concentrations. A hardwood based activated carbon was the more favorable activated carbon template, and this offered better sulfate removal than when using bituminous based activated carbon or oak wood activated carbon as the template. The hardwood-based activated carbon modified with polypyrrole removed 44.7 mg/g sulfate, and this was five times higher than for the pristine hardwood-based activated carbon. Various protocols for depositing the polypyrrole onto the activated carbon were investigated. When ferric chloride was used as an oxidant, the deposition protocol that achieved the most N + atomic percent (3.35%) while also maintaining the least oxygen atomic percent (6.22%) offered the most favorable sulfate removal. For the rapid small scale column tests, when processing the AMD water, hardwood-based activated carbon modified with poly pyrrole exhibited 33 bed volume compared to the 5 bed volume of pristine activated carbons. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. PULMONARY TOXICOLOGY OF SYNTHETIC AIR POLLUTION PARTICLES CONTAINING METAL SULFATES COMPARED TO CARBON BLACK AND DIESEL

    EPA Science Inventory

    PULMONARY TOXICITY OF SYNTHETIC AIR POLLUTION PARTICLES CONTAINING METAL SULFATES COMPARED TO CARBON BLACK AND DIESEL.

    M Daniels, A Ranade* & MJ Selgrade & MI Gilmour.
    Experimental Toxicology Division, ORD/NHEERL, U.S. EPA, RTP, NC. * Particle Technology, College Par...

  18. A jellium model of a catalyst particle in carbon nanotube growth

    NASA Astrophysics Data System (ADS)

    Artyukhov, Vasilii I.; Liu, Mingjie; Penev, Evgeni S.; Yakobson, Boris I.

    2017-06-01

    We show how a jellium model can represent a catalyst particle within the density-functional theory based approaches to the growth mechanism of carbon nanotubes (CNTs). The advantage of jellium is an abridged, less computationally taxing description of the multi-atom metal particle, while at the same time in avoiding the uncertainty of selecting a particular atomic geometry of either a solid or ever-changing liquid catalyst particle. A careful choice of jellium sphere size and its electron density as a descriptive parameter allows one to calculate the CNT-metal interface energies close to explicit full atomistic models. Further, we show that using jellium permits computing and comparing the formation of topological defects (sole pentagons or heptagons, the culprits of growth termination) as well as pentagon-heptagon pairs 5|7 (known as chirality-switching dislocation).

  19. Black carbon at a roadside site in Beijing: Temporal variations and relationships with carbon monoxide and particle number size distribution

    NASA Astrophysics Data System (ADS)

    Song, Shaojie; Wu, Ye; Xu, Jiayu; Ohara, Toshimasa; Hasegawa, Shuichi; Li, Jiaqi; Yang, Liu; Hao, Jiming

    2013-10-01

    Black carbon (BC), carbon monoxide (CO), and particle number size distribution were measured near a major urban expressway of Beijing during summer and winter field campaigns in 2009. BC was also observed at urban and rural sites. The temporal variations of BC and its relationships with CO and particle number size distribution were analyzed. The average BC concentrations at the roadside site were 12.3 and 17.9 μg m-3 during the summer and winter campaigns, respectively. BC concentrations ranked in the order of roadside > urban > rural. A general diurnal pattern at all sites showed that the higher BC levels were observed at night. The diurnal pattern of summertime BC at the roadside site followed the variations of heavy-duty diesel vehicles (HDDVs). The increased proportion of HDDVs at night contributed to high ΔBC/ΔCO ratios. This study suggests that HDDVs are an important contributor to nighttime BC and particle number concentrations of both Aitken and accumulation modes near major roadways in Beijing, especially in summer.

  20. Less-costly activated carbon for sewage treatment

    NASA Technical Reports Server (NTRS)

    Ingham, J. D.; Kalvinskas, J. J.; Mueller, W. A.

    1977-01-01

    Lignite-aided sewage treatment is based on absorption of dissolved pollutants by activated carbon. Settling sludge is removed and dried into cakes that are pyrolyzed with lignites to yield activated carbon. Lignite is less expensive than activated carbon previously used to supplement pyrolysis yield.

  1. Determining contributions of biomass burning and other sources to fine particle contemporary carbon in the western United States

    NASA Astrophysics Data System (ADS)

    Holden, Amanda S.; Sullivan, Amy P.; Munchak, Leigh A.; Kreidenweis, Sonia M.; Schichtel, Bret A.; Malm, William C.; Collett, Jeffrey L., Jr.

    2011-02-01

    Six-day integrated fine particle samples were collected at urban and rural sampling sites using Hi-Volume samplers during winter and summer 2004-2005 as part of the IMPROVE (Interagency Monitoring of PROtected Visual Environments) Radiocarbon Study. Filter samples from six sites (Grand Canyon, Mount Rainier, Phoenix, Puget Sound, Rocky Mountain National Park, and Tonto National Monument) were analyzed for levoglucosan, a tracer for biomass combustion, and other species by High-Performance Anion-Exchange Chromatography with Pulsed Amperometric Detection (HPAEC-PAD). Contemporary carbon concentrations were available from previous carbon isotope measurements at Lawrence Livermore National Laboratory. Primary contributions of biomass burning to measured fine particle contemporary carbon were estimated for residential wood burning (winter) and wild/prescribed fires (summer). Calculated contributions ranged from below detection limit to more than 100% and were typically higher at rural sites and during winter. Mannitol, a sugar alcohol emitted by fungal spores, was analyzed and used to determine contributions of fungal spores to fine particle contemporary carbon. Contributions reached up to 13% in summer samples, with higher contributions at rural sites. Concentrations of methyltetrols, oxidation products of isoprene, were also measured by HPAEC-PAD. Secondary organic aerosol (SOA) from isoprene oxidation was estimated to contribute up to 22% of measured contemporary carbon. For each sampling site, a substantial portion of the contemporary carbon was unexplained by primary biomass combustion, fungal spores, or SOA from isoprene oxidation. This unexplained fraction likely contains contributions from other SOA sources, including oxidation products of primary smoke emissions and plant emissions other than isoprene, as well as other primary particle emissions from meat cooking, plant debris, other biological aerosol particles, bio-diesel combustion, and other sources. Loss

  2. Catalytic ozonation of p-chlorobenzoic acid by activated carbon and nickel supported activated carbon prepared from petroleum coke.

    PubMed

    Li, Xukai; Zhang, Qiuyun; Tang, Lili; Lu, Ping; Sun, Fengqiang; Li, Laisheng

    2009-04-15

    The aim of this research was to investigate catalytic activity of petroleum coke, activated carbon (AC) prepared from this material, Ni supported catalyst on activated carbon (Ni/AC) in the ozonation of aqueous phase p-chlorobenzoic acid (p-CBA). Activated carbon and Ni/AC catalyst were characterized by XRD and SEM. The presence of petroleum coke did not improve the degradation of p-CBA compared to ozonation alone, but it was advantageous for p-CBA mineralization (total organic carbon, TOC, reduction), indicating the generation of highly oxidant species (*OH) in the medium. The presence of either activated carbon or Ni/AC considerably improves TOC removal during p-CBA ozonation. Ni/AC catalyst shows the better catalytic activity and stability based on five repeated tests during p-CBA ozonation. During the ozonation (50 mg/h ozone flow rate) of a 10 mg/L p-CBA (pH 4.31), it can be more mineralized in the presence of Ni/AC catalyst (5.0 g/L), TOC removal rate is over 60% in 60 min, 43% using activated carbon as catalyst, only 30% with ozonation alone.

  3. Merging allylic carbon-hydrogen and selective carbon-carbon bond activation.

    PubMed

    Masarwa, Ahmad; Didier, Dorian; Zabrodski, Tamar; Schinkel, Marvin; Ackermann, Lutz; Marek, Ilan

    2014-01-09

    Since the nineteenth century, many synthetic organic chemists have focused on developing new strategies to regio-, diastereo- and enantioselectively build carbon-carbon and carbon-heteroatom bonds in a predictable and efficient manner. Ideal syntheses should use the least number of synthetic steps, with few or no functional group transformations and by-products, and maximum atom efficiency. One potentially attractive method for the synthesis of molecular skeletons that are difficult to prepare would be through the selective activation of C-H and C-C bonds, instead of the conventional construction of new C-C bonds. Here we present an approach that exploits the multifold reactivity of easily accessible substrates with a single organometallic species to furnish complex molecular scaffolds through the merging of otherwise difficult transformations: allylic C-H and selective C-C bond activations. The resulting bifunctional nucleophilic species, all of which have an all-carbon quaternary stereogenic centre, can then be selectively derivatized by the addition of two different electrophiles to obtain more complex molecular architecture from these easily available starting materials.

  4. Merging allylic carbon-hydrogen and selective carbon-carbon bond activation

    NASA Astrophysics Data System (ADS)

    Masarwa, Ahmad; Didier, Dorian; Zabrodski, Tamar; Schinkel, Marvin; Ackermann, Lutz; Marek, Ilan

    2014-01-01

    Since the nineteenth century, many synthetic organic chemists have focused on developing new strategies to regio-, diastereo- and enantioselectively build carbon-carbon and carbon-heteroatom bonds in a predictable and efficient manner. Ideal syntheses should use the least number of synthetic steps, with few or no functional group transformations and by-products, and maximum atom efficiency. One potentially attractive method for the synthesis of molecular skeletons that are difficult to prepare would be through the selective activation of C-H and C-C bonds, instead of the conventional construction of new C-C bonds. Here we present an approach that exploits the multifold reactivity of easily accessible substrates with a single organometallic species to furnish complex molecular scaffolds through the merging of otherwise difficult transformations: allylic C-H and selective C-C bond activations. The resulting bifunctional nucleophilic species, all of which have an all-carbon quaternary stereogenic centre, can then be selectively derivatized by the addition of two different electrophiles to obtain more complex molecular architecture from these easily available starting materials.

  5. Adsorption uptake of synthetic organic chemicals by carbon nanotubes and activated carbons.

    PubMed

    Brooks, A J; Lim, Hyung-nam; Kilduff, James E

    2012-07-27

    Carbon nanotubes (CNTs) have shown great promise as high performance materials for adsorbing priority pollutants from water and wastewater. This study compared uptake of two contaminants of interest in drinking water treatment (atrazine and trichloroethylene) by nine different types of carbonaceous adsorbents: three different types of single walled carbon nanotubes (SWNTs), three different sized multi-walled nanotubes (MWNTs), two granular activated carbons (GACs) and a powdered activated carbon (PAC). On a mass basis, the activated carbons exhibited the highest uptake, followed by SWNTs and MWNTs. However, metallic impurities in SWNTs and multiple walls in MWNTs contribute to adsorbent mass but do not contribute commensurate adsorption sites. Therefore, when uptake was normalized by purity (carbon content) and surface area (instead of mass), the isotherms collapsed and much of the CNT data was comparable to the activated carbons, indicating that these two characteristics drive much of the observed differences between activated carbons and CNT materials. For the limited data set here, the Raman D:G ratio as a measure of disordered non-nanotube graphitic components was not a good predictor of adsorption from solution. Uptake of atrazine by MWNTs having a range of lengths and diameters was comparable and their Freundlich isotherms were statistically similar, and we found no impact of solution pH on the adsorption of either atrazine or trichloroethylene in the range of naturally occurring surface water (pH = 5.7-8.3). Experiments were performed using a suite of model aromatic compounds having a range of π-electron energy to investigate the role of π-π electron donor-acceptor interactions on organic compound uptake by SWNTs. For the compounds studied, hydrophobic interactions were the dominant mechanism in the uptake by both SWNTs and activated carbon. However, comparing the uptake of naphthalene and phenanthrene by activated carbon and SWNTs, size exclusion effects

  6. Adsorption uptake of synthetic organic chemicals by carbon nanotubes and activated carbons

    NASA Astrophysics Data System (ADS)

    Brooks, A. J.; Lim, Hyung-nam; Kilduff, James E.

    2012-07-01

    Carbon nanotubes (CNTs) have shown great promise as high performance materials for adsorbing priority pollutants from water and wastewater. This study compared uptake of two contaminants of interest in drinking water treatment (atrazine and trichloroethylene) by nine different types of carbonaceous adsorbents: three different types of single walled carbon nanotubes (SWNTs), three different sized multi-walled nanotubes (MWNTs), two granular activated carbons (GACs) and a powdered activated carbon (PAC). On a mass basis, the activated carbons exhibited the highest uptake, followed by SWNTs and MWNTs. However, metallic impurities in SWNTs and multiple walls in MWNTs contribute to adsorbent mass but do not contribute commensurate adsorption sites. Therefore, when uptake was normalized by purity (carbon content) and surface area (instead of mass), the isotherms collapsed and much of the CNT data was comparable to the activated carbons, indicating that these two characteristics drive much of the observed differences between activated carbons and CNT materials. For the limited data set here, the Raman D:G ratio as a measure of disordered non-nanotube graphitic components was not a good predictor of adsorption from solution. Uptake of atrazine by MWNTs having a range of lengths and diameters was comparable and their Freundlich isotherms were statistically similar, and we found no impact of solution pH on the adsorption of either atrazine or trichloroethylene in the range of naturally occurring surface water (pH = 5.7-8.3). Experiments were performed using a suite of model aromatic compounds having a range of π-electron energy to investigate the role of π-π electron donor-acceptor interactions on organic compound uptake by SWNTs. For the compounds studied, hydrophobic interactions were the dominant mechanism in the uptake by both SWNTs and activated carbon. However, comparing the uptake of naphthalene and phenanthrene by activated carbon and SWNTs, size exclusion effects

  7. Increased ultrafine particles and carbon monoxide concentrations are associated with asthma exacerbation among urban children.

    PubMed

    Evans, Kristin A; Halterman, Jill S; Hopke, Philip K; Fagnano, Maria; Rich, David Q

    2014-02-01

    Increased air pollutant concentrations have been linked to several asthma-related outcomes in children, including respiratory symptoms, medication use, and hospital visits. However, few studies have examined effects of ultrafine particles in a pediatric population. Our primary objective was to examine the effects of ambient concentrations of ultrafine particles on asthma exacerbation among urban children and determine whether consistent treatment with inhaled corticosteroids could attenuate these effects. We also explored the relationship between asthma exacerbation and ambient concentrations of accumulation mode particles, fine particles (≤2.5 micrograms [μm]; PM2.5), carbon monoxide, sulfur dioxide, and ozone. We hypothesized that increased 1-7 day concentrations of ultrafine particles and other pollutants would be associated with increases in the relative odds of an asthma exacerbation, but that this increase in risk would be attenuated among children receiving school-based corticosteroid therapy. We conducted a pilot study using data from 3 to 10 year-old children participating in the School-Based Asthma Therapy trial. Using a time-stratified case-crossover design and conditional logistic regression, we estimated the relative odds of a pediatric asthma visit treated with prednisone (n=96 visits among 74 children) associated with increased pollutant concentrations in the previous 7 days. We re-ran these analyses separately for children receiving medications through the school-based intervention and children in a usual care control group. Interquartile range increases in ultrafine particles and carbon monoxide concentrations in the previous 7 days were associated with increases in the relative odds of a pediatric asthma visit, with the largest increases observed for 4-day mean ultrafine particles (interquartile range=2088p/cm(3); OR=1.27; 95% CI=0.90-1.79) and 7-day mean carbon monoxide (interquartile range=0.17ppm; OR=1.63; 95% CI=1.03-2.59). Relative odds

  8. Increased ultrafine particles and carbon monoxide concentrations are associated with asthma exacerbation among urban children

    PubMed Central

    Evans, Kristin A.; Halterman, Jill S.; Hopke, Philip K.; Fagnano, Maria; Rich, David Q.

    2014-01-01

    Objectives Increased air pollutant concentrations have been linked to several asthma-related outcomes in children, including respiratory symptoms, medication use, and hospital visits. However, few studies have examined effects of ultrafine particles in a pediatric population. Our primary objective was to examine the effects of ambient concentrations of ultrafine particles on asthma exacerbation among urban children and determine whether consistent treatment with inhaled corticosteroids could attenuate these effects. We also explored the relationship between asthma exacerbation and ambient concentrations of accumulation mode particles, fine particles (≤ 2.5 micrograms [μm]; PM2.5), carbon monoxide, sulfur dioxide, and ozone. We hypothesized that increased 1 to 7 day concentrations of ultrafine particles and other pollutants would be associated with increases in the relative odds of an asthma exacerbation, but that this increase in risk would be attenuated among children receiving school-based corticosteroid therapy. Methods We conducted a pilot study using data from 3–10 year-old children participating in the School-Based Asthma Therapy trial. Using a time-stratified case-crossover design and conditional logistic regression, we estimated the relative odds of a pediatric asthma visit treated with prednisone (n=96 visits among 74 children) associated with increased pollutant concentrations in the previous 7 days. We re-ran these analyses separately for children receiving medications through the school-based intervention and children in a usual care control group. Results Interquartile range increases in ultrafine particles and carbon monoxide concentrations in the previous 7 days were associated with increases in the relative odds of a pediatric asthma visit, with the largest increases observed for 4-day mean ultrafine particles (interquartile range=2088 p/cm3; OR=1.27; 95% CI=0.90–1.79) and 7-day mean carbon monoxide (interquartile range=0.17 ppm; OR=1.63; 95

  9. Quantum chemical molecular dynamics simulation of single-walled carbon nanotube cap nucleation on an iron particle.

    PubMed

    Ohta, Yasuhito; Okamoto, Yoshiko; Page, Alister J; Irle, Stephan; Morokuma, Keiji

    2009-11-24

    The atomic scale details of single-walled carbon nanotube (SWNT) nucleation on metal catalyst particles are elusive to experimental observations. Computer simulation of metal-catalyzed SWNT nucleation is a challenging topic but potentially of great importance to understand the factors affecting SWNT diameters, chirality, and growth efficiency. In this work, we use nonequilibrium density functional tight-binding molecular dynamics simulations and report nucleation of sp(2)-carbon cap structures on an iron particle consisting of 38 atoms. One C(2) molecule was placed every 1.0 ps around an Fe(38) cluster for 30 ps, after which a further 410 ps of annealing simulation without carbon supply was performed. We find that sp(2)-carbon network nucleation and annealing processes occur in three sequential and repetitive stages: (A) polyyne chains on the metal surface react with each other to evolve into a Y-shaped polyyne junction, which preferentially form a five-membered ring as a nucleus; (B) polyyne chains on the first five-membered ring form an additional fused five- or six-membered ring; and (C) pentagon-to-hexagon self-healing rearrangement takes place with the help of short-lived polyyne chains, stabilized by the mobile metal atoms. The observed nucleation process resembles the formation of a fullerene cage. However, the metal particle plays a key role in differentiating the nucleation process from fullerene cage formation, most importantly by keeping the growing cap structure from closing into a fullerene cage and by keeping the carbon edge "alive" for the addition of new carbon material.

  10. Particle size and support effects in electrocatalysis.

    PubMed

    Hayden, Brian E

    2013-08-20

    Researchers increasingly recognize that, as with standard supported heterogeneous catalysts, the activity and selectivity of supported metal electrocatalysts are influenced by particle size, particle structure, and catalyst support. Studies using model supported heterogeneous catalysts have provided information about these effects. Similarly, model electrochemical studies on supported metal electrocatalysts can provide insight into the factors determining catalytic activity. High-throughput methods for catalyst synthesis and screening can determine systematic trends in activity as a function of support and particle size with excellent statistical certainty. In this Account, we describe several such studies investigating methods for dispersing precious metals on both carbon and oxide supports, with particular emphasis on the prospects for the development of low-temperature fuel-cell electrocatalysts. One key finding is a decrease in catalytic activity with decreasing particle size independent of the support for both oxygen reduction and CO oxidation on supported gold and platinum. For these reactions, there appears to be an intrinsic particle size effect that results in a loss of activity at particle sizes below 2-3 nm. A titania support, however, also increases activity of gold particles in the electrooxidation of CO and in the reduction of oxygen, with an optimum at 3 nm particle size. This optimum may represent the superposition of competing effects: a titania-induced enhanced activity versus deactivation at small particle sizes. The titania support shows catalytic activity at potentials where carbon-supported and bulk-gold surfaces are normally oxidized and CO electrooxidation is poisoned. On the other hand, platinum on amorphous titania shows a different effect: the oxidation reduction reaction is strongly poisoned in the same particle size range. We correlated the influence of the titania support with titania-induced changes in the surface redox behavior of

  11. Dynamics of Deformable Active Particles under External Flow Field

    NASA Astrophysics Data System (ADS)

    Tarama, Mitsusuke

    2017-10-01

    In most practical situations, active particles are affected by their environment, for example, by a chemical concentration gradient, light intensity, gravity, or confinement. In particular, the effect of an external flow field is important for particles swimming in a solvent fluid. For deformable active particles such as self-propelled liquid droplets and active vesicles, as well as microorganisms such as euglenas and neutrophils, a general description has been developed by focusing on shape deformation. In this review, we present our recent studies concerning the dynamics of a single active deformable particle under an external flow field. First, a set of model equations of active deformable particles including the effect of a general external flow is introduced. Then, the dynamics under two specific flow profiles is discussed: a linear shear flow, as the simplest example, and a swirl flow. In the latter case, the scattering dynamics of the active deformable particles by the swirl flow is also considered.

  12. Hydrodynamic Capture and Release of Passively Driven Particles by Active Particles Under Hele-Shaw Flows

    NASA Astrophysics Data System (ADS)

    Mishler, Grant; Tsang, Alan Cheng Hou; Pak, On Shun

    2018-03-01

    The transport of active and passive particles plays central roles in diverse biological phenomena and engineering applications. In this paper, we present a theoretical investigation of a system consisting of an active particle and a passive particle in a confined micro-fluidic flow. The introduction of an external flow is found to induce the capture of the passive particle by the active particle via long-range hydrodynamic interactions among the particles. This hydrodynamic capture mechanism relies on an attracting stable equilibrium configuration formed by the particles, which occurs when the external flow intensity exceeds a certain threshold. We evaluate this threshold by studying the stability of the equilibrium configurations analytically and numerically. Furthermore, we study the dynamics of typical capture and non-capture events and characterize the basins of attraction of the equilibrium configurations. Our findings reveal a critical dependence of the hydrodynamic capture mechanism on the external flow intensity. Through adjusting the external flow intensity across the stability threshold, we demonstrate that the active particle can capture and release the passive particle in a controllable manner. Such a capture-and-release mechanism is desirable for biomedical applications such as the capture and release of therapeutic payloads by synthetic micro-swimmers in targeted drug delivery.

  13. Activated carbon from peach stones using phosphoric acid activation at medium temperatures.

    PubMed

    Kim, Dong-Su

    2004-01-01

    In the present study, the activation features of phosphoric acid have been investigated using waste peach stones as the raw material in the production of granular activated carbon. Thermogravimetry/differential thermal analysis was conducted to characterize the thermal behavior of peach stone and titration method was used to evaluate the adsorption capacity of the produced activated carbon. It was observed that the iodine value of the activated carbon increased with activation temperature. However, temperatures higher than 500 degrees C caused a thermal destruction, which resulted in the decrease of the adsorption capacity. Activation longer than 1.5 h at 500 degrees C resulted in thermal degradation of the porous structure of the activated carbon. The adsorption capacity was enhanced with increasing of amounts of phosphoric acid, however, excessive phosphoric acid caused a decrease in the iodine value. In addition, it was found that the carbon yields generally decreased with activation temperature and activation time. Scanning electron microscopy analysis was conducted to observe the changes in the poros structure of the activated carbon produced in different temperatures. Activation of carbon by phosphoric acid was found to be superior to that by CaCl2 and gas activation. The activated carbon produced from peach stone was applied as an adsorbent in the treatment of synthesized wastewater containing cadmium ion and its adsorption capacity was found to be as good as that of the commercial one.

  14. Preparation of activated carbon monolith by application of phenolic resins as carbon precursors

    NASA Astrophysics Data System (ADS)

    Sajad, Mehran; Kazemzad, Mahmood; Hosseinnia, Azarmidokht

    2014-04-01

    In the current work, activated carbon monoliths have been prepared by application of different phenolic hydrocarbons namely catechol and resorcinol as carbon precursors. For synthesis of carbon monolith, the precursors have been mixed with Genapol PF-10 as template and then polymerized in the presence of lysine as catalyst. Then the polymerized monolith carbonized in inert atmosphere at 700°C and activated by water steam at 550°C. It was found that resorcinol polymerization is easier than catechol and occurred at 90°C while for polymerization of catechol elevated temperature of 120°C at hydrothermal condition is necessary. The prepared activated carbon samples have been characterized by various analysis methods including scanning electron microscopy (SEM), surface area measurement, and transmission electron microscopy (TEM). The adsorptions of three different aromatic hydrocarbons by the prepared activated carbon samples have also been investigated by high performance liquid chromatography (HPLC) and UV-Vis spectroscopy. It was found that carbon monolith prepared by catechol as carbon precursor has higher adsorpability and strength in comparison with the other sample. The higher performance of carbon monolith prepared by catechol can be associated with its higher active sites in comparison with resorcinol.

  15. Combining activated carbon adsorption with heterogeneous photocatalytic oxidation: Lack of synergy for biologically treated greywater and tetraethylene glycol dimethyl ether

    PubMed Central

    Gulyas, Holger; Argáez, Ángel Santiago Oria; Kong, Fanzhuo; Jorge, Carlos Liriano; Eggers, Susanne; Otterpohl, Ralf

    2013-01-01

    The aim of the study was to evaluate whether the addition of activated carbon in the photocatalytic oxidation of biologically pretreated greywater and of a polar aliphatic compound gives synergy, as previously demonstrated with phenol. Photocatalytic oxidation kinetics were recorded with fivefold concentrated biologically pretreated greywater and with aqueous tetraethylene glycol dimethyl ether solutions using a UV lamp and the photocatalyst TiO2 P25 in the presence and the absence of powdered activated carbon. The synergy factor, SF, was quantified as the ratio of photocatalytic oxidation rate constant in the presence of powdered activated carbon to the rate constant without activated carbon. No synergy was observed for the greywater concentrate (SF ≈ 1). For the aliphatic compound, tetraethylene glycol dimethyl ether, addition of activated carbon actually had an inhibiting effect on photocatalysis (SF < 1), while synergy was confirmed in reference experiments using aqueous phenol solutions. The absence of synergy for the greywater concentrate can be explained by low adsorbability of its organic constituents by activated carbon. Inhibition of the photocatalytic oxidation of tetraethylene glycol dimethyl ether by addition of powdered activated carbon was attributed to shading of the photocatalyst by the activated carbon particles. It was assumed that synergy in the hybrid process was limited to aromatic organics. Regardless of the lack of synergy in the case of biologically pretreated greywater, the addition of powdered activated carbon is advantageous since, due to additional adsorptive removal of organics, photocatalytic oxidation resulted in a 60% lower organic concentration when activated carbon was present after the same UV irradiation time. PMID:24191472

  16. Making Activated Carbon by Wet Pressurized Pyrolysis

    NASA Technical Reports Server (NTRS)

    Fisher, John W.; Pisharody, Suresh; Wignarajah, K.; Moran, Mark

    2006-01-01

    A wet pressurized pyrolysis (wet carbonization) process has been invented as a means of producing activated carbon from a wide variety of inedible biomass consisting principally of plant wastes. The principal intended use of this activated carbon is room-temperature adsorption of pollutant gases from cooled incinerator exhaust streams. Activated carbon is highly porous and has a large surface area. The surface area depends strongly on the raw material and the production process. Coconut shells and bituminous coal are the primary raw materials that, until now, were converted into activated carbon of commercially acceptable quality by use of traditional production processes that involve activation by use of steam or carbon dioxide. In the wet pressurized pyrolysis process, the plant material is subjected to high pressure and temperature in an aqueous medium in the absence of oxygen for a specified amount of time to break carbon-oxygen bonds in the organic material and modify the structure of the material to obtain large surface area. Plant materials that have been used in demonstrations of the process include inedible parts of wheat, rice, potato, soybean, and tomato plants. The raw plant material is ground and mixed with a specified proportion of water. The mixture is placed in a stirred autoclave, wherein it is pyrolized at a temperature between 450 and 590 F (approximately between 230 and 310 C) and a pressure between 1 and 1.4 kpsi (approximately between 7 and 10 MPa) for a time between 5 minutes and 1 hour. The solid fraction remaining after wet carbonization is dried, then activated at a temperature of 500 F (260 C) in nitrogen gas. The activated carbon thus produced is comparable to commercial activated carbon. It can be used to adsorb oxides of sulfur, oxides of nitrogen, and trace amounts of hydrocarbons, any or all of which can be present in flue gas. Alternatively, the dried solid fraction can be used, even without the activation treatment, to absorb

  17. Sources and mixing state of size-resolved elemental carbon particles in a European megacity: Paris

    NASA Astrophysics Data System (ADS)

    Healy, R. M.; Sciare, J.; Poulain, L.; Kamili, K.; Merkel, M.; Müller, T.; Wiedensohler, A.; Eckhardt, S.; Stohl, A.; Sarda-Estève, R.; McGillicuddy, E.; O'Connor, I. P.; Sodeau, J. R.; Wenger, J. C.

    2012-02-01

    An Aerosol Time-Of-Flight Mass Spectrometer (ATOFMS) was deployed to investigate the size-resolved chemical composition of single particles at an urban background site in Paris, France, as part of the MEGAPOLI winter campaign in January/February 2010. ATOFMS particle counts were scaled to match coincident Twin Differential Mobility Particle Sizer (TDMPS) data in order to generate hourly size-resolved mass concentrations for the single particle classes observed. The total scaled ATOFMS particle mass concentration in the size range 150-1067 nm was found to agree very well with the sum of concurrent High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) and Multi-Angle Absorption Photometer (MAAP) mass concentration measurements of organic carbon (OC), inorganic ions and black carbon (BC) (R2 = 0.91). Clustering analysis of the ATOFMS single particle mass spectra allowed the separation of elemental carbon (EC) particles into four classes: (i) EC attributed to biomass burning (ECbiomass), (ii) EC attributed to traffic (ECtraffic), (iii) EC internally mixed with OC and ammonium sulfate (ECOCSOx), and (iv) EC internally mixed with OC and ammonium nitrate (ECOCNOx). Average hourly mass concentrations for EC-containing particles detected by the ATOFMS were found to agree reasonably well with semi-continuous quantitative thermal/optical EC and optical BC measurements (r2 = 0.61 and 0.65-0.68 respectively, n = 552). The EC particle mass assigned to fossil fuel and biomass burning sources also agreed reasonably well with BC mass fractions assigned to the same sources using seven-wavelength aethalometer data (r2 = 0.60 and 0.48, respectively, n = 568). Agreement between the ATOFMS and other instrumentation improved noticeably when a period influenced by significantly aged, internally mixed EC particles was removed from the intercomparison. 88% and 12% of EC particle mass was apportioned to fossil fuel and biomass burning respectively using the ATOFMS data

  18. Heterogeneous Oxidation of Atmospheric Organic Aerosol: Kinetics of Changes to the Amount and Oxidation State of Particle-Phase Organic Carbon.

    PubMed

    Kroll, Jesse H; Lim, Christopher Y; Kessler, Sean H; Wilson, Kevin R

    2015-11-05

    Atmospheric oxidation reactions are known to affect the chemical composition of organic aerosol (OA) particles over timescales of several days, but the details of such oxidative aging reactions are poorly understood. In this study we examine the rates and products of a key class of aging reaction, the heterogeneous oxidation of particle-phase organic species by the gas-phase hydroxyl radical (OH). We compile and reanalyze a number of previous studies from our laboratories involving the oxidation of single-component organic particles. All kinetic and product data are described on a common basis, enabling a straightforward comparison among different chemical systems and experimental conditions. Oxidation chemistry is described in terms of changes to key ensemble properties of the OA, rather than to its detailed molecular composition, focusing on two quantities in particular, the amount and the oxidation state of the particle-phase carbon. Heterogeneous oxidation increases the oxidation state of particulate carbon, with the rate of increase determined by the detailed chemical mechanism. At the same time, the amount of particle-phase carbon decreases with oxidation, due to fragmentation (C-C scission) reactions that form small, volatile products that escape to the gas phase. In contrast to the oxidation state increase, the rate of carbon loss is nearly uniform among most systems studied. Extrapolation of these results to atmospheric conditions indicates that heterogeneous oxidation can have a substantial effect on the amount and composition of atmospheric OA over timescales of several days, a prediction that is broadly in line with available measurements of OA evolution over such long timescales. In particular, 3-13% of particle-phase carbon is lost to the gas phase after one week of heterogeneous oxidation. Our results indicate that oxidative aging represents an important sink for particulate organic carbon, and more generally that fragmentation reactions play a major

  19. Size-dependent surface phase change of lithium iron phosphate during carbon coating

    NASA Astrophysics Data System (ADS)

    Wang, Jiajun; Yang, Jinli; Tang, Yongji; Liu, Jian; Zhang, Yong; Liang, Guoxian; Gauthier, Michel; Karen Chen-Wiegart, Yu-Chen; Norouzi Banis, Mohammad; Li, Xifei; Li, Ruying; Wang, Jun; Sham, T. K.; Sun, Xueliang

    2014-03-01

    Carbon coating is a simple, effective and common technique for improving the conductivity of active materials in lithium ion batteries. However, carbon coating provides a strong reducing atmosphere and many factors remain unclear concerning the interface nature and underlying interaction mechanism that occurs between carbon and the active materials. Here, we present a size-dependent surface phase change occurring in lithium iron phosphate during the carbon coating process. Intriguingly, nanoscale particles exhibit an extremely high stability during the carbon coating process, whereas microscale particles display a direct visualization of surface phase changes occurring at the interface at elevated temperatures. Our findings provide a comprehensive understanding of the effect of particle size during carbon coating and the interface interaction that occurs on carbon-coated battery material—allowing for further improvement in materials synthesis and manufacturing processes for advanced battery materials.

  20. Pyrophoric metal-carbon foam composites and methods of making the same

    DOEpatents

    Gash, Alexander E [Brentwood, CA; Satcher, Jr., Joe H.; Simpson, Randall L [Livermore, CA; Baumann, Theodore F [Discovery Bay, CA; Worsley, Marcus A [Belmont, CA

    2012-05-08

    A method for creating a pyrophoric material according to one embodiment includes thermally activating a carbon foam for creating micropores therein; contacting the activated carbon foam with a liquid solution comprising a metal salt for depositing metal ions in the carbon foam; and reducing the metal ions in the foam to metal particles. A pyrophoric material in yet another embodiment includes a pyrophoric metal-carbon foam composite comprising a carbon foam having micropores and mesopores and a surface area of greater than or equal to about 2000 m.sup.2/g, and metal particles in the pores of the carbon foam. Additional methods and materials are also disclosed.

  1. Consequence of chitosan treating on the adsorption of humic acid by granular activated carbon.

    PubMed

    Maghsoodloo, Sh; Noroozi, B; Haghi, A K; Sorial, G A

    2011-07-15

    In this work, equilibrium and kinetic adsorption of humic acid (HA) onto chitosan treated granular activated carbon (MGAC) has been investigated and compared to the granular activated carbon (GAC). The adsorption equilibrium data showed that adsorption behaviour of HA could be described reasonably well by Langmuir adsorption isotherm for GAC and Freundlich adsorption isotherm for MGAC. It was shown that pre-adsorption of chitosan onto the surface of GAC improved the adsorption capacity of HA changing the predominant adsorption mechanism. Monolayer capacities for the adsorption of HA onto GAC and MGAC were calculated 55.8 mg/g and 71.4 mg/g, respectively. Kinetic studies showed that film diffusion and intra-particle diffusion were simultaneously operating during the adsorption process for MGAC. Copyright © 2011 Elsevier B.V. All rights reserved.

  2. ULTRAFINE CARBON PARTICLES INDUCE IL-8 EXPRESSION IN HUMAN AIRWAY EPITHELIAL CELLS THROUGH A POST-TRANSCRIPTIONAL MECHANISM

    EPA Science Inventory

    Ultrafine carbon particles induce IL-8 expression in human airway
    epithelial cells through a post-transcritpional mechanism
    Epidemiological studies suggest that ultrafine particles contribute to
    particulate matter (PM) - induced adverse health effects. IL-8 is an
    i...

  3. Transport of the moving barrier driven by chiral active particles

    NASA Astrophysics Data System (ADS)

    Liao, Jing-jing; Huang, Xiao-qun; Ai, Bao-quan

    2018-03-01

    Transport of a moving V-shaped barrier exposed to a bath of chiral active particles is investigated in a two-dimensional channel. Due to the chirality of active particles and the transversal asymmetry of the barrier position, active particles can power and steer the directed transport of the barrier in the longitudinal direction. The transport of the barrier is determined by the chirality of active particles. The moving barrier and active particles move in the opposite directions. The average velocity of the barrier is much larger than that of active particles. There exist optimal parameters (the chirality, the self-propulsion speed, the packing fraction, and the channel width) at which the average velocity of the barrier takes its maximal value. In particular, tailoring the geometry of the barrier and the active concentration provides novel strategies to control the transport properties of micro-objects or cargoes in an active medium.

  4. Exposure to carbon monoxide, fine particle mass, and ultrafine particle number in Jakarta, Indonesia: effect of commute mode.

    PubMed

    Both, Adam F; Westerdahl, Dane; Fruin, Scott; Haryanto, Budi; Marshall, Julian D

    2013-01-15

    We measured real-time exposure to PM(2.5), ultrafine PM (particle number) and carbon monoxide (CO) for commuting workers school children, and traffic police, in Jakarta, Indonesia. In total, we measured exposures for 36 individuals covering 93 days. Commuters in private cars experienced mean (st dev) exposures of 22 (9.4) ppm CO, 91 (38) μg/m(3)PM(2.5), and 290 (150)×10(3) particles cm(-3). Mean concentrations were higher in public transport than in private cars for PM(2.5) (difference in means: 22%) and particle counts (54%), but not CO, likely reflecting in-vehicle particle losses in private cars owing to air-conditioning. However, average commute times were longer for private car commuters than public transport commuters (in our sample, 24% longer: 3.0 vs. 2.3 h per day). Commute and traffic-related exposures experienced by Jakarta residents are among the highest in the world, owing to high on-road concentrations and multi-hour commutes. Copyright © 2012 Elsevier B.V. All rights reserved.

  5. Carbon dioxide capture by activated methyl diethanol amine impregnated mesoporous carbon

    NASA Astrophysics Data System (ADS)

    Ardhyarini, N.; Krisnandi, Y. K.

    2017-07-01

    Activated Methyl Diethanol Amine (aMDEA) were impregnated onto the surface of the mesoporous carbon to increase carbon dioxide (CO2) adsorption capacity. The mesoporous carbon was synthesized through soft template method with phloroglucinol as carbon precursor and triblock copolymer (Pluronic F127) as structure directing agent. These activated MDEA impregnated mesoporous carbon (aMDEA-MC) were characterized using various solid characterization techniques. CO2 adsorption was investigated using autoclaved-reactor in the batch system. The FTIR spectrum of aMDEA-MC had absorption peaks at 3395 cm-1 and 1031 cm-1 which are characteristic for O-H stretch and amine C-N stretch in MDEA. The elemental analyzer showed that nitrogen content on the mesoporous carbon increased after impregnation by 23 wt.%. The BET surface area and total pore volume of mesoporous carbon decreased after impregnation, 43 wt.% and 50 wt.%, respectively. The maximum CO2 adsorption capacity of aMDEA43-MC was 2.63 mmol/g (298 K, 5 psi and pure CO2). This is 64 % and 35 % higher compared to the CO2 adsorption capacity of the starting MC and also commercially available activated carbon with higher surface area. All the results suggest that MDEA-MC is a promising adsorbent for CO2 capture.

  6. Collective Surfing of Chemically Active Particles

    NASA Astrophysics Data System (ADS)

    Masoud, Hassan; Shelley, Michael J.

    2014-03-01

    We study theoretically the collective dynamics of immotile particles bound to a 2D surface atop a 3D fluid layer. These particles are chemically active and produce a chemical concentration field that creates surface-tension gradients along the surface. The resultant Marangoni stresses create flows that carry the particles, possibly concentrating them. For a 3D diffusion-dominated concentration field and Stokesian fluid we show that the surface dynamics of active particle density can be determined using nonlocal 2D surface operators. Remarkably, we also show that for both deep or shallow fluid layers this surface dynamics reduces to the 2D Keller-Segel model for the collective chemotactic aggregation of slime mold colonies. Mathematical analysis has established that the Keller-Segel model can yield finite-time, finite-mass concentration singularities. We show that such singular behavior occurs in our finite-depth system, and study the associated 3D flow structures.

  7. Supercritical carbon dioxide processing of active pharmaceutical ingredients for polymorphic control and for complex formation.

    PubMed

    Moribe, Kunikazu; Tozuka, Yuichi; Yamamoto, Keiji

    2008-02-14

    Supercritical fluid technique have been exploited in extraction, separation and crystallization processes. In the field of pharmaceutics, supercritical carbon dioxide (scCO(2)) has been used for the purpose of micronization, polymorphic control, and preparation of solid dispersion and complexes. Particle design of active pharmaceutical ingredients is important to make the solid dosage forms with suitable physicochemical properties. Control of the characteristic properties of particles, such as size, shape, crystal structure and morphology is required to optimize the formulation. For solubility enhancement of poorly water-soluble drugs, preparation of the solid dispersion or the complexation with proper drugs or excipients should be a promising approach. This review focuses on aspects of polymorphic control and complexation behavior of active pharmaceutical ingredients by scCO(2) processing.

  8. Dynamic pesticide removal with activated carbon fibers.

    PubMed

    Martín-Gullón, I; Font, R

    2001-02-01

    Rapid small-scale minicolumn tests were carried out to simulate the atrazine adsorption in water phase with three pelletized pitch-based activated carbon fibers (ACF) and one commercial granular activated carbon (GAC). Initial atrazine solutions were prepared with pretreated ground water. Minicolumn tests showed that the performance of highly activated carbon fibers (surface area of 1700 m2/g) is around 7 times better than the commercial GAC (with surface area at around 1100 m2/g), whereas carbon fibers with medium activation degree (surface area of 1500 m2/g) had a removal efficiency worse than the commercial carbon. The high removal efficiency of the highly activated ACF is due to the wide-opened microstructure of the material, with an appreciable contribution of the low size mesopores, maintaining at these conditions a fast kinetic adsorption rate rather than a selective adsorbent for micropollutants vs. natural organic matter.

  9. Improved Wear Resistance of Low Carbon Steel with Plasma Melt Injection of WC Particles

    NASA Astrophysics Data System (ADS)

    Liu, Aiguo; Guo, Mianhuan; Hu, Hailong

    2010-08-01

    Surface of a low carbon steel Q235 substrate was melted by a plasma torch, and tungsten carbide (WC) particles were injected into the melt pool. WC reinforced surface metal matrix composite (MMC) was synthesized. Dry sliding wear behavior of the surface MMC was studied and compared with the substrate. The results show that dry sliding wear resistance of low carbon steel can be greatly improved by plasma melt injection of WC particles. Hardness of the surface MMC is much higher than that of the substrate. The high hardness lowers the adhesion and abrasion of the surface MMC, and also the friction coefficient of it. The oxides formed in the sliding process also help to lower the friction coefficient. In this way, the dry sliding wear resistance of the surface MMC is greatly improved.

  10. Carbon loading of alveolar macrophages in adults and children exposed to biomass smoke particles.

    PubMed

    Kulkarni, Neeta S; Prudon, Benjamin; Panditi, Sri L; Abebe, Yekoye; Grigg, Jonathan

    2005-06-01

    Exposure to carbonaceous particles from biomass burning is associated with increased respiratory morbidity in both women and children in the developing world. However, the amount of carbon reaching lower airway cells has not been determined in these populations. Alveolar macrophages (AM) remove inhaled particulate matter (PM), and are implicated in the pathogenesis of PM-induced lung disease. In this study, we aimed to compare AM carbon loading in women and children exposed to biomass PM in Gondar, Ethiopia, with individuals exposed to fossil-fuel PM in the developed world (Leicester, UK). To achieve these aims, we sampled AM from Ethiopian mothers and children, and from UK adults and children using induced sputum (IS). AM were imaged under light microscopy, and the total two-dimensional surface area of carbon within each AM determined by image analysis. AM containing carbon were detected in all subjects. The total surface area of carbon per AM was higher in Ethiopian women (n=10) compared with UK adults (n=10, median 9.19 vs. 0.71 microm2/AM, p=0.0002). Similarly, the total surface area of carbon per AM was higher in Ethiopian children (n=10) compared with UK children (n=10, 3.32 vs. 0.44 microm2/AM, p=0.0002). However, loading in Ethiopian children was lower than paired maternal levels (3.32 vs. 9.19 microm2/AM, p=0.011). We conclude that analysis of AM obtained by induced sputum is a practical way of quantifying natural exposure of the lower airway to carbonaceous particles from the burning of biomass fuels.

  11. Formation of secondary organic aerosol coating on black carbon particles near vehicular emissions

    NASA Astrophysics Data System (ADS)

    Lee, Alex K. Y.; Chen, Chia-Li; Liu, Jun; Price, Derek J.; Betha, Raghu; Russell, Lynn M.; Zhang, Xiaolu; Cappa, Christopher D.

    2017-12-01

    Black carbon (BC) emitted from incomplete combustion can result in significant impacts on air quality and climate. Understanding the mixing state of ambient BC and the chemical characteristics of its associated coatings is particularly important to evaluate BC fate and environmental impacts. In this study, we investigate the formation of organic coatings on BC particles in an urban environment (Fontana, California) under hot and dry conditions using a soot-particle aerosol mass spectrometer (SP-AMS). The SP-AMS was operated in a configuration that can exclusively detect refractory BC (rBC) particles and their coatings. Using the -log(NOx / NOy) ratio as a proxy for photochemical age of air masses, substantial formation of secondary organic aerosol (SOA) coatings on rBC particles was observed due to active photochemistry in the afternoon, whereas primary organic aerosol (POA) components were strongly associated with rBC from fresh vehicular emissions in the morning rush hours. There is also evidence that cooking-related organic aerosols were externally mixed from rBC. Positive matrix factorization and elemental analysis illustrate that most of the observed SOA coatings were freshly formed, providing an opportunity to examine SOA coating formation on rBCs near vehicular emissions. Approximately 7-20 wt % of secondary organic and inorganic species were estimated to be internally mixed with rBC on average, implying that rBC is unlikely the major condensation sink of SOA in this study. Comparison of our results to a co-located standard high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) measurement suggests that at least a portion of SOA materials condensed on rBC surfaces were chemically different from oxygenated organic aerosol (OOA) particles that were externally mixed with rBC, although they could both be generated from local photochemistry.

  12. Removal of airborne microorganisms emitted from a wastewater treatment oxidation ditch by adsorption on activated carbon.

    PubMed

    Li, Lin; Gao, Min; Liu, Junxin; Guo, Xuesong

    2011-01-01

    Bioaerosol emissions from wastewater and wastewater treatment processes are a significant subgroup of atmospheric aerosols. Most previous work has focused on the evaluation of their biological risks. In this study, however, the adsorption method was applied to reduce airborne microorganisms generated from a pilot scale wastewater treatment facility with oxidation ditch. Results showed adsorption on granule activated carbon (GAC) was an efficient method for the purification of airborne microorganisms. The GAC itself had a maximum adsorption capacity of 2217 CFU/g for airborne bacteria and 225 CFU/g for fungi with a flow rate of 1.50 m3/hr. Over 85% of airborne bacteria and fungi emitted from the oxidation ditch were adsorbed within 80 hr of continuous operation mode. Most of them had a particle size of 0.65-4.7 microm. Those airborne microorganisms with small particle size were apt to be adsorbed. The SEM/EDAX, BET and Boehm's titration methods were applied to analyse the physicochemical characteristics of the GAC. Relationships between GAC surface characteristics and its adsorption performance demonstrated that porous structure, large surface area, and hydrophobicity rendered GAC an effective absorber of airborne microorganisms. Two regenerate methods, ultraviolet irradiation and high pressure vapor, were compared for the regeneration of used activated carbon. High pressure vapor was an effective technique as it totally destroyed the microorganisms adhered to the activated carbon. Microscopic observation was also carried out to investigate original and used adsorbents.

  13. Impact of Combustion Efficiency of Open Biomass Burning on the Mixing State of Black Carbon Containing Particles

    NASA Astrophysics Data System (ADS)

    PAN, X.; Kanaya, Y.; Taketani, F.; Miyakawa, T.; Inomata, S.; Komazaki, Y.; Tanimoto, H.; Uno, I.; Wang, Z.

    2014-12-01

    Open biomass burning (OBB) experiments were performed in the laboratory environment to investigate the mixing state of refractory black carbon (rBC) in fresh smoke and its dependence on combustion state. A Single-Particle Soot Photometer (SP2) was adopted to measure variation of number size distribution of rBC-containing particles in high temporal resolution. General combustion state of each OBB case was indicated by modified combustion efficiency (MCE) using accumulated enhancement of mixing ratios of carbon dioxide and carbon monoxide during the experiments. We found that mass equivalent diameter (MED) of rBC increased apparently with increase of MCE values, indicating the flaming-dominant combustion tend to produce the rBC particles with relative larger size, probably because of coagulation processes in high concentration condition. Coating thickness of rBC-containing particle was calculated by leading edge only fitting (LEO-fitting) method. In the present study we defined the rBC-containing particles with shell/core (S/C) ratio larger than 2 as "thickly coated" and that less then 1.5 as "thinly coated". As a result, thickly coated rBC particles normally had a relatively small core (MED of rBC less than 150 nm) and its number fraction showed an evident decrease as a function of MCE value, whereas, larger rBC particles (MED larger than 150 nm) were normally thinly coated. Number fraction of both thinly coated and uncoated rBC particles had an positive correlation with MCE value. Substantial amount of light scattering particles (LSP) observed in the smoldering-dominant OBB plumes could partially explain the increase of number fraction of coated rBC particles. ΔrBC/ΔCO ratio showed a good positive correlation with MCE with an average value of 16.8 (1.2 - 51.6) ng/m3/ppbv, and ΔrBC/ΔCO2 ratio was found 628.7 ng/m3/ppmv, generally consistent with previous studies.

  14. Carbon Nanostructure of Diesel Soot Particles Emitted from 2 and 4 Stroke Marine Engines Burning Different Fuels.

    PubMed

    Lee, Won-Ju; Park, Seul-Hyun; Jang, Se-Hyun; Kim, Hwajin; Choi, Sung Kuk; Cho, Kwon-Hae; Cho, Ik-Soon; Lee, Sang-Min; Choi, Jae-Hyuk

    2018-03-01

    Diesel soot particles were sampled from 2-stroke and 4-stroke engines that burned two different fuels (Bunker A and C, respectively), and the effects of the engine and fuel types on the structural characteristics of the soot particle were analyzed. The carbon nanostructures of the sampled particles were characterized using various techniques. The results showed that the soot sample collected from the 4-stroke engine, which burned Bunker C, has a higher degree of order of the carbon nanostructure than the sample collected from the 2-stroke engine, which burned Bunker A. Furthermore, the difference in the exhaust gas temperatures originating from the different engine and fuel types can affect the nanostructure of the soot emitted from marine diesel engines.

  15. Stochastic dynamics of coupled active particles in an overdamped limit

    NASA Astrophysics Data System (ADS)

    Ann, Minjung; Lee, Kong-Ju-Bock; Park, Pyeong Jun

    2015-10-01

    We introduce a model for Brownian dynamics of coupled active particles in an overdamped limit. Our system consists of several identical active particles and one passive particle. Each active particle is elastically coupled to the passive particle and there is no direct coupling among the active particles. We investigate the dynamics of the system with respect to the number of active particles, viscous friction, and coupling between the active and passive particles. For this purpose, we consider an intracellular transport process as an application of our model and perform a Brownian dynamics simulation using realistic parameters for processive molecular motors such as kinesin-1. We determine an adequate energy conversion function for molecular motors and study the dynamics of intracellular transport by multiple motors. The results show that the average velocity of the coupled system is not affected by the number of active motors and that the stall force increases linearly as the number of motors increases. Our results are consistent with well-known experimental observations. We also examine the effects of coupling between the motors and the cargo, as well as of the spatial distribution of the motors around the cargo. Our model might provide a physical explanation of the cooperation among active motors in the cellular transport processes.

  16. Production of activated carbon from TCR char

    NASA Astrophysics Data System (ADS)

    Stenzel, Fabian; Heberlein, Markus; Klinner, Tobias; Hornung, Andreas

    2016-04-01

    The utilization of char for adsorptive purposes is known since the 18th century. At that time the char was made of wood or bones and used for decoloration of fluids. In the 20th century the production of activated carbon in an industrial scale was started. The today's raw materials for activated carbon production are hard coal, peat, wood or coconut shells. All these materials entail costs especially the latter. Thus, the utilization of carbon rich residues (biomass) is an interesting economic opportunity because it is available for no costs or even can create income. The char is produced by thermo-catalytic reforming (TCR®). This process is a combination of an intermediate pyrolysis and subsequently a reforming step. During the pyrolysis step the material is decomposed in a vapor and a solid carbon enriched phase. In the second step the vapor and the solid phase get in an intensive contact and the quality of both materials is improved via the reforming process. Subsequently, the condensables are precipitated from the vapor phase and a permanent gas as well as oil is obtained. Both are suitable for heat and power production which is a clear advantage of the TCR® process. The obtained biochar from the TCR® process has special properties. This material has a very low hydrogen and oxygen content. Its stability is comparable to hard coal or anthracite. Therefore it consists almost only of carbon and ash. The latter depends from input material. Furthermore the surface structure and area can be influenced during the reforming step. Depending from temperature and residence time the number of micro pores and the surface area can be increased. Preliminary investigations with methylene blue solution have shown that a TCR® char made of digestate from anaerobic digestion has adsorptive properties. The decoloration of the solution was achieved. A further influencing factor of the adsorption performance is the particle size. Based on the results of the preliminary tests a

  17. Carbon species in PM10 particle fraction at different monitoring sites.

    PubMed

    Godec, Ranka; Jakovljević, Ivana; Šega, Krešimir; Čačković, Mirjana; Bešlić, Ivan; Davila, Silvije; Pehnec, Gordana

    2016-09-01

    The aim of this study was to determine and compare the levels of elemental carbon (EC), organic carbon (OC) and polycyclic aromatic hydrocarbons (PAHs) mass concentrations in PM10 particles (particles with aerodynamic diameter less than 10 μm) between seasons (winter and summer) and at different monitoring sites (urban background and rural industrial). Daily samples of airborne particles were collected on pre-fired quartz fibre filters. PM10 mass concentrations were determined gravimetrically. Samples were analysed for OC and EC with the thermal/optical transmittance method (TOT) and for PAHs by high-performance liquid chromatography (HPLC) with a fluorescence detector. Measurements showed seasonal and spatial variations of mass concentrations for carbon species and for all of the measured PAHs (Flu, Pyr, Chry, BaA, BbF, BaP, BkF, BghiP and IP) in PM10 at the urban site and rural monitoring site described here. Diagnostic PAH ratios (Flu/(Flu + Pyr), BaA/(BaA + Cry), IP/(IP + BghiP), BaP/BghiP, IP/BghiP and BaP/(BaP + Chry)) make it possible to assess the sources of pollution, and these showed that diesel vehicles accounted for most pollution at the rural-industrial (RI) site in the summer, whereas coal and wood combustion were the causes of winter pollution. This difference between winter and summer PAH ratios were more expressed at the RI site than at the UB site because at the UB site the predominant heating fuel was gas. The OC/EC ratio yielded the same conclusion. Factor analysis showed that EC and OC originated from traffic at both sites, PAHs with 5 or more benzene rings originated from wood pellets industry or biomass burning, while Pyr and Flu originated from diesel combustion or as a consequence of different atmospheric behaviour - evaporation and participation in oxidation and photo oxidation processes. Copyright © 2016 Elsevier Ltd. All rights reserved.

  18. Transport of active ellipsoidal particles in ratchet potentials

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ai, Bao-Quan, E-mail: aibq@scnu.edu.cn; Wu, Jian-Chun

    2014-03-07

    Rectified transport of active ellipsoidal particles is numerically investigated in a two-dimensional asymmetric potential. The out-of-equilibrium condition for the active particle is an intrinsic property, which can break thermodynamical equilibrium and induce the directed transport. It is found that the perfect sphere particle can facilitate the rectification, while the needlelike particle destroys the directed transport. There exist optimized values of the parameters (the self-propelled velocity, the torque acting on the body) at which the average velocity takes its maximal value. For the ellipsoidal particle with not large asymmetric parameter, the average velocity decreases with increasing the rotational diffusion rate, whilemore » for the needlelike particle (very large asymmetric parameter), the average velocity is a peaked function of the rotational diffusion rate. By introducing a finite load, particles with different shapes (or different self-propelled velocities) will move to the opposite directions, which is able to separate particles of different shapes (or different self-propelled velocities)« less

  19. Wollastonite Carbonation in Water-Bearing Supercritical CO2: Effects of Particle Size.

    PubMed

    Min, Yujia; Li, Qingyun; Voltolini, Marco; Kneafsey, Timothy; Jun, Young-Shin

    2017-11-07

    The performance of geologic CO 2 sequestration (GCS) can be affected by CO 2 mineralization and changes in the permeability of geologic formations resulting from interactions between water-bearing supercritical CO 2 (scCO 2 ) and silicates in reservoir rocks. However, without an understanding of the size effects, the findings in previous studies using nanometer- or micrometer-size particles cannot be applied to the bulk rock in field sites. In this study, we report the effects of particle sizes on the carbonation of wollastonite (CaSiO 3 ) at 60 °C and 100 bar in water-bearing scCO 2 . After normalization by the surface area, the thickness of the reacted wollastonite layer on the surfaces was independent of particle sizes. After 20 h, the reaction was not controlled by the kinetics of surface reactions but by the diffusion of water-bearing scCO 2 across the product layer on wollastonite surfaces. Among the products of reaction, amorphous silica, rather than calcite, covered the wollastonite surface and acted as a diffusion barrier to water-bearing scCO 2 . The product layer was not highly porous, with a specific surface area 10 times smaller than that of the altered amorphous silica formed at the wollastonite surface in aqueous solution. These findings can help us evaluate the impacts of mineral carbonation in water-bearing scCO 2 .

  20. Swinging motion of active deformable particles in Poiseuille flow

    NASA Astrophysics Data System (ADS)

    Tarama, Mitsusuke

    2017-08-01

    Dynamics of active deformable particles in an external Poiseuille flow is investigated. To make the analysis general, we employ time-evolution equations derived from symmetry considerations that take into account an elliptical shape deformation. First, we clarify the relation of our model to that of rigid active particles. Then, we study the dynamical modes that active deformable particles exhibit by changing the strength of the external flow. We emphasize the difference between the active particles that tend to self-propel parallel to the elliptical shape deformation and those self-propelling perpendicularly. In particular, a swinging motion around the centerline far from the channel walls is discussed in detail.

  1. JPL Activated Carbon Treatment System (ACTS) for sewage

    NASA Technical Reports Server (NTRS)

    1976-01-01

    An Activated Carbon Treatment System (ACTS) was developed for sewage treatment and is being applied to a one-million gallon per day sewage treatment pilot plant in Orange County California. Activities reported include pyrolysis and activation of carbon-sewage sludge, and activated carbon treatment of sewage to meet ocean discharge standards. The ACTS Sewage treatment operations include carbon-sewage treatment, primary and secondary clarifiers, gravity (multi-media) filter, filter press dewatering, flash drying of carbon-sewage filter cake, and sludge pyrolysis and activation. Tests were conducted on a laboratory scale, 10,000 gallon per day demonstration plant and pilot test equipment. Preliminary economic studies are favorable to the ACTS process relative to activated sludge treatment for a 175,000,000 gallon per day sewage treatment plant.

  2. Removal of chromium(III) from tannery wastewater using activated carbon from sugar industrial waste.

    PubMed

    Fahim, N F; Barsoum, B N; Eid, A E; Khalil, M S

    2006-08-21

    Chromium is commonly found in huge quantities in tannery wastewaters. For this reason, the removal and recovery of the chromium content of tannery wastewaters is crucial for environmental protection and economic reasons. Removal and recovery of chromium were carried out by using low-cost potential adsorbents. For this purpose three types of activated carbon; C1, the waste generated from sugar industry as waste products and the others (C2, C3) are commercial granular activated carbon, were used. The adsorption process and extent of adsorption are dependent on the physical and chemical characteristics of the adsorbent, adsorbate and experimental condition. The effect of pH, particle size and different adsorbent on the adsorption isotherm of Cr(III) was studied in batch system. The sorption data fitted well with Langmuir adsorption model. The efficiencies of activated carbon for the removal of Cr(III) were found to be 98.86, 98.6 and 93 % for C1, C2 and C3, respectively. The order of selectivity is C1>C2>C3 for removal of Cr(III) from tannery wastewater. Carbon "C1" of the highest surface area (520.66 m(2)/g) and calcium content (333.3 mg/l) has the highest adsorptive capacity for removal of Cr(III). The results revealed that the trivalent chromium is significantly adsorbed on activated carbon collected from sugar industry as waste products and the method could be used economically as an efficient technique for removal of Cr(III) and purification of tannery wastewaters.

  3. Active Brownian particles escaping a channel in single file.

    PubMed

    Locatelli, Emanuele; Baldovin, Fulvio; Orlandini, Enzo; Pierno, Matteo

    2015-02-01

    Active particles may happen to be confined in channels so narrow that they cannot overtake each other (single-file conditions). This interesting situation reveals nontrivial physical features as a consequence of the strong interparticle correlations developed in collective rearrangements. We consider a minimal two-dimensional model for active Brownian particles with the aim of studying the modifications introduced by activity with respect to the classical (passive) single-file picture. Depending on whether their motion is dominated by translational or rotational diffusion, we find that active Brownian particles in single file may arrange into clusters that are continuously merging and splitting (active clusters) or merely reproduce passive-motion paradigms, respectively. We show that activity conveys to self-propelled particles a strategic advantage for trespassing narrow channels against external biases (e.g., the gravitational field).

  4. Active Brownian particles escaping a channel in single file

    NASA Astrophysics Data System (ADS)

    Locatelli, Emanuele; Baldovin, Fulvio; Orlandini, Enzo; Pierno, Matteo

    2015-02-01

    Active particles may happen to be confined in channels so narrow that they cannot overtake each other (single-file conditions). This interesting situation reveals nontrivial physical features as a consequence of the strong interparticle correlations developed in collective rearrangements. We consider a minimal two-dimensional model for active Brownian particles with the aim of studying the modifications introduced by activity with respect to the classical (passive) single-file picture. Depending on whether their motion is dominated by translational or rotational diffusion, we find that active Brownian particles in single file may arrange into clusters that are continuously merging and splitting (active clusters) or merely reproduce passive-motion paradigms, respectively. We show that activity conveys to self-propelled particles a strategic advantage for trespassing narrow channels against external biases (e.g., the gravitational field).

  5. Gold nano-particle formation from crystalline AuCN: Comparison of thermal, plasma- and ion-beam activated decomposition

    NASA Astrophysics Data System (ADS)

    Beck, Mihály T.; Bertóti, Imre; Mohai, Miklós; Németh, Péter; Jakab, Emma; Szabó, László; Szépvölgyi, János

    2017-02-01

    In this work, in addition to the conventional thermal process, two non-conventional ways, the plasma and ion beam activations are described for preparing gold nanoparticles from microcrystalline AuCN precursor. The phase formation at plasma and ion beam treatments was compared with that at thermal treatments and the products and transformations were characterized by thermogravimetry-mass-spectrometry (TG-MS), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). TG-MS measurements in Ar atmosphere revealed that AuCN decomposition starts at 400 °C and completes at ≈700 °C with evolution of gaseous (CN)2. XPS and TEM show that in heat treatment at 450 °C for 1 h in Ar, loss of nitrogen and carbon occurs and small, 5-30 nm gold particles forms. Heating at 450 °C for 10 h in sealed ampoule, much larger, 60-200 nm size and well faceted Au particles develop together with a fibrous (CN)n polymer phase, and the Au crystallites are covered by a 3-5 nm thick polymer shell. Low pressure Ar plasma treatment at 300 eV energy results in 4-20 nm size Au particles and removes most of the nitrogen and part of carbon. During Ar+ ion bombardment with 2500 eV energy, 5-30 nm size Au crystallites form already in 10 min, with preferential loss of nitrogen and with increased amount of carbon residue. The results suggest that plasma and ion beam activation, acting similarly to thermal treatment, may be used to prepare Au nanoparticles from AuCN on selected surface areas either by depositing AuCN precursors on selected regions or by focusing the applied ionized radiation. Thus they may offer alternative ways for preparing tailor-made catalysts, electronic devices and sensors for different applications.

  6. Biogas pre-upgrading by adsorption of trace compounds onto granular activated carbons and an activated carbon fiber-cloth.

    PubMed

    Boulinguiez, B; Le Cloirec, P

    2009-01-01

    The study assesses the adsorption onto activated carbon materials of selected volatile organic compounds -VOCs- (dichloromethane, 2-propanol, toluene, siloxane D4) in a biogas matrix composed of methane and carbon dioxide (55:45 v/v). Three different adsorbents are tested, two of them are granular activated carbon (GAC), and the last is an activated carbon fiber-cloth (ACFC). The adsorption isotherm data are fitted by different models by nonlinear regression. The Langmuir-Freundlich model appears to be the adequate one to describe the adsorption phenomena independently of the VOC considered or the adsorbent. The adsorbents present attractive adsorption capacity of the undesirable compounds in biogas atmosphere though the maximum adsorption capacities for a VOC are quite different from each other. The adsorption kinetics are characterized through three coefficients: the initial adsorption coefficient, the external film mass transfer coefficient and the internal diffusion coefficient of Weber. The ACFC demonstrates advanced kinetic yields compared to the granular activated carbon materials whatever VOC is considered. Therefore, pre-upgrading of biogas produced from wastewater sludge or co-digestion system by adsorption onto activated carbon appears worth investigating. Especially with ACFC material that presents correct adsorption capacities toward VOCs and concrete regeneration process opportunity to realize such process.

  7. Differentiating the associations of black carbon and fine particle with daily mortality in a Chinese city.

    PubMed

    Geng, Fuhai; Hua, Jing; Mu, Zhe; Peng, Li; Xu, Xiaohui; Chen, Renjie; Kan, Haidong

    2013-01-01

    There is only limited monitoring data of black carbon for epidemiologic analyses. In the current study, we used the distributed lag models to evaluate the association between mortality outcomes (both total and cause-specific) and exposure to black carbon and fine particle (PM(2.5)) in Shanghai, China. During our research period, the mean daily concentrations of black carbon and PM(2.5) were 3.9 μg/m3 and 53.9 μg/m3, respectively. The regression results showed that black carbon was significantly associated with total and cardiovascular mortality, but not with respiratory mortality. An inter-quartile range increase (2.7 μg/m3) of black carbon corresponded to a 2.3% (95% confidence interval [CI]: 0.6-4.1), 3.2% (95% CI: 0.6-5.7), and 0.6% (95% CI: -4.5 to 5.7) increase in total, cardiovascular and respiratory mortality, respectively. When adjusted for PM(2.5), the effects of black carbon increased and remained statistically significant; in contrast, the associations of PM(2.5) with daily mortality decreased and became statistically insignificant after adjustment for black carbon. To our knowledge, this is the first study in China, or even in Asian developing countries, to report the acute effect of black carbon and PM(2.5) on daily mortality simultaneously. Our findings suggest that black carbon is a valuable additional air quality indicator to evaluate the health risks of ambient particles. Copyright © 2012 Elsevier Inc. All rights reserved.

  8. Small particles big effect? - Investigating ice nucleation abilities of soot particles

    NASA Astrophysics Data System (ADS)

    Mahrt, Fabian; David, Robert O.; Lohmann, Ulrike; Stopford, Chris; Wu, Zhijun; Kanji, Zamin A.

    2017-04-01

    Atmospheric soot particles are primary particles produced by incomplete combustion of biomass and/or fossil fuels. Thus soot mainly originates from anthropogenic emissions, stemming from combustion related processes in transport vehicles, industrial and residential uses. Such soot particles are generally complex mixtures of black carbon (BC) and organic matter (OM) (Bond et al., 2013; Petzold et al., 2013), depending on the sources and the interaction of the primary particles with other atmospheric matter and/or gases BC absorbs solar radiation having a warming effect on global climate. It can also act as a heterogeneous ice nucleating particle (INP) and thus impact cloud-radiation interactions, potentially cooling the climate (Lohmann, 2002). Previous studies, however, have shown conflicting results concerning the ice nucleation ability of soot, limiting the ability to predict its effects on Earth's radiation budget. Here we present a laboratory study where we systematically investigate the ice nucleation behavior of different soot particles. Commercial soot samples are used, including an amorphous, industrial carbon frequently used in coatings and coloring (FW 200, Orion Engineered Carbons) and a fullerene soot (572497 ALDRICH), e.g. used as catalyst. In addition, we use soot generated from a propane flame Combustion Aerosol Standard Generator (miniCAST, JING AG), as a proxy for atmospheric soot particles. The ice nucleation ability of these soot types is tested on size-selected particles for a wide temperature range from 253 K to 218 K, using the Horizontal Ice Nucleation Chamber (HINC), a Continuous Flow Diffusion Chamber (CFDC) (Kanji and Abbatt, 2009). Ice nucleation results from these soot surrogates will be compared to chemically more complex real world samples, collected on filters. Filters will be collected during the 2016/2017 winter haze periods in Beijing, China and represent atmospheric soot particles with sources from both industrial and residential

  9. Benefit-cost analysis of commercially available activated carbon filters for indoor ozone removal in single-family homes.

    PubMed

    Aldred, J R; Darling, E; Morrison, G; Siegel, J; Corsi, R L

    2016-06-01

    This study involved the development of a model for evaluating the potential costs and benefits of ozone control by activated carbon filtration in single-family homes. The modeling effort included the prediction of indoor ozone with and without activated carbon filtration in the HVAC system. As one application, the model was used to predict benefit-to-cost ratios for single-family homes in 12 American cities in five different climate zones. Health benefits were evaluated using disability-adjusted life-years and included city-specific age demographics for each simulation. Costs of commercially available activated carbon filters included capital cost differences when compared to conventional HVAC filters of similar particle removal efficiency, energy penalties due to additional pressure drop, and regional utility rates. The average indoor ozone removal effectiveness ranged from 4 to 20% across the 12 target cities and was largely limited by HVAC system operation time. For the parameters selected in this study, the mean predicted benefit-to-cost ratios for 1-inch filters were >1.0 in 10 of the 12 cities. The benefits of residential activated carbon filters were greatest in cities with high seasonal ozone and HVAC usage, suggesting the importance of targeting such conditions for activated carbon filter applications. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  10. Exposure to nanoscale particles and fibers during machining of hybrid advanced composites containing carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Bello, Dhimiter; Wardle, Brian L.; Yamamoto, Namiko; Guzman deVilloria, Roberto; Garcia, Enrique J.; Hart, Anastasios J.; Ahn, Kwangseog; Ellenbecker, Michael J.; Hallock, Marilyn

    2009-01-01

    This study investigated airborne exposures to nanoscale particles and fibers generated during dry and wet abrasive machining of two three-phase advanced composite systems containing carbon nanotubes (CNTs), micron-diameter continuous fibers (carbon or alumina), and thermoset polymer matrices. Exposures were evaluated with a suite of complementary instruments, including real-time particle number concentration and size distribution (0.005-20 μm), electron microscopy, and integrated sampling for fibers and respirable particulate at the source and breathing zone of the operator. Wet cutting, the usual procedure for such composites, did not produce exposures significantly different than background whereas dry cutting, without any emissions controls, provided a worst-case exposure and this article focuses here. Overall particle release levels, peaks in the size distribution of the particles, and surface area of released particles (including size distribution) were not significantly different for composites with and without CNTs. The majority of released particle surface area originated from the respirable (1-10 μm) fraction, whereas the nano fraction contributed 10% of the surface area. CNTs, either individual or in bundles, were not observed in extensive electron microscopy of collected samples. The mean number concentration of peaks for dry cutting was composite dependent and varied over an order of magnitude with highest values for thicker laminates at the source being >1 × 106 particles cm-3. Concentration of respirable fibers for dry cutting at the source ranged from 2 to 4 fibers cm-3 depending on the composite type. Further investigation is required and underway to determine the effects of various exposure determinants, such as specimen and tool geometry, on particle release and effectiveness of controls.

  11. Activity of different proteinaceous ice nucleating particles

    NASA Astrophysics Data System (ADS)

    Hartmann, Susann; Augustin-Bauditz, Stefanie; Grawe, Sarah; Ling, Meilee; Hellner, Lisa; Zapf, Jean-Michel; Šantl-Temkiv, Tina; Pummer, Bernhard; Boesen, Thomas; Wex, Heike; Finster, Kai; Stratmann, Frank

    2017-04-01

    A variety of microorganisms (bacteria, fungi, lichen) from land produce protein structures, which act as a template for ice nucleation [1]. Also marine sources of ice nucleating particles (INPs) came in focus in the recent years. The atmospheric spatio-temporal distribution of INPs from microorganisms is still not well known. However, it is often assumed that the observed onset of atmospheric ice nucleation (T>-20°C) is due to the existence of ice-nucleation active biological particles. In this study we compare the ice nucleation activity of different proteinaceous particles produced by bacteria and fungi. For bacteria we investigate (i) cells and fragments of Pseudomonas syringae from commercially available SnomaxTM and (ii) the Pseudomonas syringae INA protein expressed in living Escherichia coli bacteria. We also analyzed freeze-dried leaves [2] where we assume that proteinaceous particles are responsible for the ice nucleation activity. For fungi the widespread soil fungus Mortierella alpina was investigated which had been extracted from natural soil [3]. Immersion freezing experiments are performed at the cold stage LINA (Leipzig Ice Nucleation Array). We attempt to describe the activity of a single proteinaceous ice nucleating particle [4] in order to achieve direct comparability. Further, the results are compared with complex natural systems e.g. soil dust. The objectives of this study are to clarify potential differences in the ice nucleation potential of proteinaceous particles and to draw conclusions concerning the need to differentiate them for modelling purposes. 1. Szyrmer, W. and I. Zawadzki, Biogenic and anthropogenic sources of ice-forming nuclei: A review, Bull. Amer. Meteorol. Soc., 1997. 2. Schnell, R.C. and G. Vali, Biogenic ice nucleai .1: Terrestrial and marine sources, doi: 10.1175/1520-0469(1976)033<1554:binpit>2.0.co;2, 1976. 3. Froehlich-Nowoisky, J. et al., Ice nucleation activity in the widespread soil fungus Mortierella alpina, doi: 10

  12. Carbon black reinforced polymethyl methacrylate (PMMA)-based composite particles: preparation, characterization, and application

    NASA Astrophysics Data System (ADS)

    Liang, Tian; Yan, Chunjie; Zhou, Sen; Zhang, Yonghan; Yang, Bipeng

    2017-10-01

    Carbon black (CB) is an excellent filler to reinforce polymers because of its unique thermal and mechanical properties. Thus, a type of modified carbon black (MCB) was developed, which led to reduced filler aggregation in methyl methacrylate (MMA) monomers and resulted in homogeneous dispersion in the polymethyl methacrylate (PMMA) substrate. The PMMA-MCB composite particles that were prepared in this work possessed remarkable and stable properties. Therefore, they can be used as an ultra-lightweight proppant (ULWP). Fourier transform infrared spectroscopy showed that CB was successfully modified and the MCB was well dispersed in the PMMA matrix. Results of crushing rate and differential scanning calorimetry demonstrated that MCB could significantly enhance the thermal and mechanical performance of the ULWP. Heat treatment of the ULWP under a nitrogen atmosphere could also clearly enhance its performance in various aspects. The process of modifying CB, the approach of synthesizing PMMA-MCB composite particles, and their mechanism were systematically investigated in this work.

  13. Enhanced adsorption of humic acids on ordered mesoporous carbon compared with microporous activated carbon.

    PubMed

    Liu, Fengling; Xu, Zhaoyi; Wan, Haiqin; Wan, Yuqiu; Zheng, Shourong; Zhu, Dongqiang

    2011-04-01

    Humic acids are ubiquitous in surface and underground waters and may pose potential risk to human health when present in drinking water sources. In this study, ordered mesoporous carbon was synthesized by means of a hard template method and further characterized by X-ray diffraction, N2 adsorption, transition electron microscopy, elemental analysis, and zeta-potential measurement. Batch experiments were conducted to evaluate adsorption of two humic acids from coal and soil, respectively, on the synthesized carbon. For comparison, a commercial microporous activated carbon and nonporous graphite were included as additional adsorbents; moreover, phenol was adopted as a small probe adsorbate. Pore size distribution characterization showed that the synthesized carbon had ordered mesoporous structure, whereas the activated carbon was composed mainly of micropores with a much broader pore size distribution. Accordingly, adsorption of the two humic acids was substantially lower on the activated carbon than on the synthesized carbon, because of the size-exclusion effect. In contrast, the synthesized carbon and activated carbon showed comparable adsorption for phenol when the size-exclusion effect was not in operation. Additionally, we verified by size-exclusion chromatography studies that the synthesized carbon exhibited greater adsorption for the large humic acid fraction than the activated carbon. The pH dependence of adsorption on the three carbonaceous adsorbents was also compared between the two test humic acids. The findings highlight the potential of using ordered mesoporous carbon as a superior adsorbent for the removal of humic acids. Copyright © 2011 SETAC.

  14. Acid dissolution experiments - Carbonates and the 6.8-micrometer bands in interplanetary dust particles

    NASA Technical Reports Server (NTRS)

    Sandford, S. A.

    1986-01-01

    A chemical dissolution experiment on an interplanetary dust particle (IDP) showed that carbonates, not acid-insoluble organic compounds, were responsible for virtually all the absorption at 6.8 micrometers seen in the infrared spectra of this particle. The IDP examined had an infrared spectrum characteristic of layer-lattice silicates and belongs to a class of IDP's whose spectra resemble those of protostellar objects like W33 A, which also exhibit a band at 6.8 micrometers.

  15. Population and hierarchy of active species in gold iron oxide catalysts for carbon monoxide oxidation

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    He, Qian; Freakley, Simon J.; Edwards, Jennifer K.

    The identity of active species in supported gold catalysts for low temperature carbon monoxide oxidation remains an unsettled debate. With large amounts of experimental evidence supporting theories of either gold nanoparticles or sub-nm gold species being active, it was recently proposed that a size-dependent activity hierarchy should exist. Here we study the diverging catalytic behaviors after heat treatment of Au/FeO x materials prepared via co-precipitation and deposition precipitation methods. After ruling out any support effects, the gold particle size distributions in different catalysts are quantitatively studied using aberration corrected scanning transmission electron microscopy (STEM). A counting protocol is developed tomore » reveal the true particle size distribution from HAADF-STEM images, which reliably includes all the gold species present. As a result, correlation of the populations of the various gold species present with catalysis results demonstrate that a size-dependent activity hierarchy must exist in the Au/FeO x catalyst.« less

  16. Population and hierarchy of active species in gold iron oxide catalysts for carbon monoxide oxidation

    DOE PAGES

    He, Qian; Freakley, Simon J.; Edwards, Jennifer K.; ...

    2016-09-27

    The identity of active species in supported gold catalysts for low temperature carbon monoxide oxidation remains an unsettled debate. With large amounts of experimental evidence supporting theories of either gold nanoparticles or sub-nm gold species being active, it was recently proposed that a size-dependent activity hierarchy should exist. Here we study the diverging catalytic behaviors after heat treatment of Au/FeO x materials prepared via co-precipitation and deposition precipitation methods. After ruling out any support effects, the gold particle size distributions in different catalysts are quantitatively studied using aberration corrected scanning transmission electron microscopy (STEM). A counting protocol is developed tomore » reveal the true particle size distribution from HAADF-STEM images, which reliably includes all the gold species present. As a result, correlation of the populations of the various gold species present with catalysis results demonstrate that a size-dependent activity hierarchy must exist in the Au/FeO x catalyst.« less

  17. Population and hierarchy of active species in gold iron oxide catalysts for carbon monoxide oxidation.

    PubMed

    He, Qian; Freakley, Simon J; Edwards, Jennifer K; Carley, Albert F; Borisevich, Albina Y; Mineo, Yuki; Haruta, Masatake; Hutchings, Graham J; Kiely, Christopher J

    2016-09-27

    The identity of active species in supported gold catalysts for low temperature carbon monoxide oxidation remains an unsettled debate. With large amounts of experimental evidence supporting theories of either gold nanoparticles or sub-nm gold species being active, it was recently proposed that a size-dependent activity hierarchy should exist. Here we study the diverging catalytic behaviours after heat treatment of Au/FeO x materials prepared via co-precipitation and deposition precipitation methods. After ruling out any support effects, the gold particle size distributions in different catalysts are quantitatively studied using aberration corrected scanning transmission electron microscopy (STEM). A counting protocol is developed to reveal the true particle size distribution from HAADF-STEM images, which reliably includes all the gold species present. Correlation of the populations of the various gold species present with catalysis results demonstrate that a size-dependent activity hierarchy must exist in the Au/FeO x catalyst.

  18. High efficient preparation of carbon nanotube-grafted carbon fibers with the improved tensile strength

    NASA Astrophysics Data System (ADS)

    Fan, Wenxin; Wang, Yanxiang; Wang, Chengguo; Chen, Jiqiang; Wang, Qifen; Yuan, Yan; Niu, Fangxu

    2016-02-01

    An innovative technique has been developed to obtain the uniform catalyst coating on continuously moving carbon fibers. Carbon nanotube (CNT)-grafted carbon fibers with significantly improved tensile strength have been succeeded to produce by using chemical vapor deposition (CVD) when compared to the tensile strength of untreated carbon fibers. The critical requirements for preparation of CNT-grafted carbon fibers with high tensile strength have been found, mainly including (i) the obtainment of uniform coating of catalyst particles with small particle size, (ii) the low catalyst-induced and mechano-chemical degradation of carbon fibers, and (iii) the high catalyst activity which could facilitate the healing and strengthening of carbon fibers during the growth of CNTs. The optimum growth temperature was found to be about 500 °C, and the optimum catalyst is Ni due to its highest activity, there is a pronounced increase of 10% in tensile strength of carbon fibers after CNT growth at 500 °C by using Ni catalyst. Based on the observation from HRTEM images, a healing and crosslink model of neighboring carbon crystals by CNTs has been formulated to reveal the main reason that causes an increase in tensile strength of carbon fibers after the growth of CNTs. Such results have provided the theoretical and experimental foundation for the large-scale preparation of CNT-grafted carbon fibers with the improved tensile strength, significantly promoting the development of CNT-grafted carbon fiber reinforced polymer composites.

  19. Webinar Presentation: Black Carbon and Other Light-absorbing Particles in Snow in Central North America and North China

    EPA Pesticide Factsheets

    This presentation, Black Carbon and Other Light-absorbing Particles in Snow in Central North America and North China, was given at the STAR Black Carbon 2016 Webinar Series: Accounting for Impact, Emissions, and Uncertainty held on Nov. 7, 2016.

  20. Effects of Particle Filters and Accelerated Engine Replacement on Heavy-Duty Diesel Vehicle Emissions of Black Carbon, Nitrogen Oxides, and Ultrafine Particles

    NASA Astrophysics Data System (ADS)

    Kirchstetter, T.; Preble, C.; Dallmann, T. R.; DeMartini, S. J.; Tang, N. W.; Kreisberg, N. M.; Hering, S. V.; Harley, R. A.

    2013-12-01

    Diesel particle filters have become widely used in the United States since the introduction in 2007 of a more stringent exhaust particulate matter emission standard for new heavy-duty diesel vehicle engines. California has instituted additional regulations requiring retrofit or replacement of older in-use engines to accelerate emission reductions and air quality improvements. This presentation summarizes pollutant emission changes measured over several field campaigns at the Port of Oakland in the San Francisco Bay Area associated with diesel particulate filter use and accelerated modernization of the heavy-duty truck fleet. Pollutants in the exhaust plumes of hundreds of heavy-duty trucks en route to the Port were measured in 2009, 2010, 2011, and 2013. Ultrafine particle number, black carbon (BC), nitrogen oxides (NOx), and nitrogen dioxide (NO2) concentrations were measured at a frequency ≤ 1 Hz and normalized to measured carbon dioxide concentrations to quantify fuel-based emission factors (grams of pollutant emitted per kilogram of diesel consumed). The size distribution of particles in truck exhaust plumes was also measured at 1 Hz. In the two most recent campaigns, emissions were linked on a truck-by-truck basis to installed emission control equipment via the matching of transcribed license plates to a Port truck database. Accelerated replacement of older engines with newer engines and retrofit of trucks with diesel particle filters reduced fleet-average emissions of BC and NOx. Preliminary results from the two most recent field campaigns indicate that trucks without diesel particle filters emit 4 times more BC than filter-equipped trucks. Diesel particle filters increase emissions of NO2, however, and filter-equipped trucks have NO2/NOx ratios that are 4 to 7 times greater than trucks without filters. Preliminary findings related to particle size distribution indicate that (a) most trucks emitted particles characterized by a single mode of approximately

  1. Computational modeling of electrically conductive networks formed by graphene nanoplatelet-carbon nanotube hybrid particles

    NASA Astrophysics Data System (ADS)

    Mora, A.; Han, F.; Lubineau, G.

    2018-04-01

    One strategy to ensure that nanofiller networks in a polymer composite percolate at low volume fractions is to promote segregation. In a segregated structure, the concentration of nanofillers is kept low in some regions of the sample. In turn, the concentration in the remaining regions is much higher than the average concentration of the sample. This selective placement of the nanofillers ensures percolation at low average concentration. One original strategy to promote segregation is by tuning the shape of the nanofillers. We use a computational approach to study the conductive networks formed by hybrid particles obtained by growing carbon nanotubes (CNTs) on graphene nanoplatelets (GNPs). The objective of this study is (1) to show that the higher electrical conductivity of these composites is due to the hybrid particles forming a segregated structure and (2) to understand which parameters defining the hybrid particles determine the efficiency of the segregation. We construct a microstructure to observe the conducting paths and determine whether a segregated structure has indeed been formed inside the composite. A measure of efficiency is presented based on the fraction of nanofillers that contribute to the conductive network. Then, the efficiency of the hybrid-particle networks is compared to those of three other networks of carbon-based nanofillers in which no hybrid particles are used: only CNTs, only GNPs, and a mix of CNTs and GNPs. Finally, some parameters of the hybrid particle are studied: the CNT density on the GNPs, and the CNT and GNP geometries. We also present recommendations for the further improvement of a composite’s conductivity based on these parameters.

  2. Cross-stream migration of active particles

    NASA Astrophysics Data System (ADS)

    Uspal, William; Katuri, Jaideep; Simmchen, Juliane; Miguel-Lopez, Albert; Sanchez, Samuel

    For natural microswimmers, the interplay of swimming activity and external flow can promote robust directed motion, e.g. propulsion against (upstream rheotaxis) or perpendicular to the direction of flow. These effects are generally attributed to their complex body shapes and flagellar beat patterns. Here, using catalytic Janus particles as a model system, we report on a strong directional response that naturally emerges for spherical active particles in a channel flow. The particles align their propulsion axis to be perpendicular to both the direction of flow and the normal vector of a nearby bounding surface. We develop a deterministic theoretical model that captures this spontaneous transverse orientational order. We show how the directional response emerges from the interplay of external shear flow and swimmer/surface interactions (e.g., hydrodynamic interactions) that originate in swimming activity. Finally, adding the effect of thermal noise, we obtain probability distributions for the swimmer orientation that show good agreement with the experimental probability distributions. Our findings show that the qualitative response of microswimmers to flow is sensitive to the detailed interaction between individual microswimmers and bounding surfaces.

  3. Interaction of Heavy Metal Ions with Carbon and Iron Based Particles

    PubMed Central

    Fialova, Dana; Kremplova, Monika; Melichar, Lukas; Kopel, Pavel; Hynek, David; Adam, Vojtech; Kizek, Rene

    2014-01-01

    Due to the rapid development of industry and associated production of toxic waste, especially heavy metals, there is a great interest in creating and upgrading new sorption materials to remove these pollutants from the environment. This study aims to determine the effectiveness of different carbon forms (graphene, expanded carbon, multi-wall nanotubes) and paramagnetic particles (Fe2O3) for adsorption of cadmium(II), lead(II), and copper(II) on its surface, with different interaction time from 1 min to 24 h. The main attention is paid to the detection of these metals using differential pulse voltammetry. Based on the obtained results, graphene and Fe2O3 are found to be good candidates for removal of heavy metals from the environment. PMID:28788566

  4. PULMONARY AND CARDIAC GENE EXPRESSION FOLLOWING ACUTE ULTRAFINE CARBON PARTICLE INHALATION IN HYPERTENSIVE RATS

    EPA Science Inventory

    Inhalation of ultrafine carbon particles (ufCP) causes cardiac physiological changes without marked pulmonary injury or inflammation. We hypothesized that acute ufCP exposure of 13 months old Spontaneously Hypertensive (SH) rats will cause differential effects on the lung and hea...

  5. Carbon Dioxide (CO2) Adsorption by Activated Carbon Functionalized with Deep Eutectic Solvent (DES)

    NASA Astrophysics Data System (ADS)

    Zulkurnai, N. Z.; Ali, U. F. Md.; Ibrahim, N.; Manan, N. S. Abdul

    2017-06-01

    In recent years, carbon dioxide (CO2) emission has become a major concern as the amount of the emitted gas significantly increases annually. Consequently, this phenomenon contributes to global warming. Several CO2 capture methods, including chemical adsorption by activated carbon, have been proposed. In this study, activated carbon was prepared from sea mango (Cerbera odollam), which was functionalized with deep eutectic solvent (DES) composed of choline chloride and glycerol to increase the efficiency of CO2 capture. The samples underwent pre-carbonization and carbonization processes at 200 °C and 500 °C, respectively, with nitrogen gas and flowing several gases, namely, CO2 and steam, and then followed by impregnation with 50 phosphoric acid (H3PO4) at 1:2 precursor-to-activant ratio. The prepared activated carbon was impregnated with DES at 1:2 precursor-to-activant ratio. The optimum CO2 adsorption capacity of the activated carbon was obtained by using CO2 gas treatment method (9.851 mgCO2/gsol), followed by the absence of gases (9.685 mgCO2/gsol), steam (9.636 mgCO2/gsol), and N2 (9.536 mgCO2/gsol).

  6. Examining responses of ecosystem carbon exchange to environmental changes using particle filtering mathod

    NASA Astrophysics Data System (ADS)

    Yokozawa, M.

    2017-12-01

    Attention has been paid to the agricultural field that could regulate ecosystem carbon exchange by water management and residual treatments. However, there have been less known about the dynamic responses of the ecosystem to environmental changes. In this study, focussing on paddy field, where CO2 emissions due to microbial decomposition of organic matter are suppressed and alternatively CH4 emitted under flooding condition during rice growth season and subsequently CO2 emission following the fallow season after harvest, the responses of ecosystem carbon exchange were examined. We conducted model data fusion analysis for examining the response of cropland-atmosphere carbon exchange to environmental variation. The used model consists of two sub models, paddy rice growth sub-model and soil decomposition sub-model. The crop growth sub-model mimics the rice plant growth processes including formation of reproductive organs as well as leaf expansion. The soil decomposition sub-model simulates the decomposition process of soil organic carbon. Assimilating the data on the time changes in CO2 flux measured by eddy covariance method, rice plant biomass, LAI and the final yield with the model, the parameters were calibrated using a stochastic optimization algorithm with a particle filter method. The particle filter method, which is one of the Monte Carlo filters, enable us to evaluating time changes in parameters based on the observed data until the time and to make prediction of the system. Iterative filtering and prediction with changing parameters and/or boundary condition enable us to obtain time changes in parameters governing the crop production as well as carbon exchange. In this study, we focused on the parameters related to crop production as well as soil carbon storage. As the results, the calibrated model with estimated parameters could accurately predict the NEE flux in the subsequent years. The temperature sensitivity, denoted by Q10s in the decomposition rate of

  7. Reuse performance of granular-activated carbon and activated carbon fiber in catalyzed peroxymonosulfate oxidation.

    PubMed

    Yang, Shiying; Li, Lei; Xiao, Tuo; Zhang, Jun; Shao, Xueting

    2017-03-01

    Recently, activated carbon was investigated as an efficient heterogeneous metal-free catalyst to directly activate peroxymonosulfate (PMS) for degradation of organic compounds. In this paper, the reuse performance and the possible deactivation reasons of granular-activated carbon (GAC) and activated carbon fiber (ACF) in PMS activation were investigated. As results indicated, the reusability of GAC, especially in the presence of high PMS dosage, was relatively superior to ACF in catalyzed PMS oxidation of Acid Orange 7 (AO7), which is much more easily adsorbed by ACF than by GAC. Pre-oxidation experiments were studied and it was demonstrated that PMS oxidation on ACF would retard ACF's deactivation to a big extent. After pre-adsorption with AO7, the catalytic ability of both GAC and ACF evidently diminished. However, when methanol was employed to extract the AO7-spent ACF, the catalytic ability could recover quite a bit. GAC and ACF could also effectively catalyze PMS to degrade Reactive Black 5 (RB5), which is very difficult to be adsorbed even by ACF, but both GAC and ACF have poor reuse performance for RB5 degradation. The original organic compounds or intermediate products adsorbed by GAC or ACF would be possibly responsible for the deactivation.

  8. SORPTION OF ELEMENTAL MERCURY BY ACTIVATED CARBONS

    EPA Science Inventory

    The mechanisms and rate of elemental mercury (HgO) capture by activated carbons have been studied using a bench-scale apparatus. Three types of activated carbons, two of which are thermally activated (PC-100 and FGD) and one with elemental sulfur (S) impregnated in it (HGR), were...

  9. Applicability of effective pair potentials for active Brownian particles.

    PubMed

    Rein, Markus; Speck, Thomas

    2016-09-01

    We have performed a case study investigating a recently proposed scheme to obtain an effective pair potential for active Brownian particles (Farage et al., Phys. Rev. E 91, 042310 (2015)). Applying this scheme to the Lennard-Jones potential, numerical simulations of active Brownian particles are compared to simulations of passive Brownian particles interacting by the effective pair potential. Analyzing the static pair correlations, our results indicate a limited range of activity parameters (speed and orientational correlation time) for which we obtain quantitative, or even qualitative, agreement. Moreover, we find a qualitatively different behavior for the virial pressure even for small propulsion speeds. Combining these findings we conclude that beyond linear response active particles exhibit genuine non-equilibrium properties that cannot be captured by effective pair interaction alone.

  10. Dry particle coating of polymer particles for tailor-made product properties

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Blümel, C., E-mail: karl-ernst.wirth@fau.de; Schmidt, J., E-mail: karl-ernst.wirth@fau.de; Dielesen, A., E-mail: karl-ernst.wirth@fau.de

    2014-05-15

    Disperse polymer powders with tailor-made particle properties are of increasing interest in industrial applications such as Selective Laser Beam Melting processes (SLM). This study focuses on dry particle coating processes to improve the conductivity of the insulating polymer powder in order to assemble conductive devices. Therefore PP particles were coated with Carbon Black nanoparticles in a dry particle coating process. This process was investigated in dependence of process time and mass fraction of Carbon Black. The conductivity of the functionalized powders was measured by impedance spectroscopy. It was found that there is a dependence of process time, respectively coating ratiomore » and conductivity. The powder shows higher conductivities with increasing number of guest particles per host particle surface area, i.e. there is a correlation between surface functionalization density and conductivity. The assembled composite particles open new possibilities for processing distinct polymers such as PP in SLM process. The fundamentals of the dry particle coating process of PP host particles with Carbon Black guest particles as well as the influence on the electrical conductivity will be discussed.« less

  11. Comparison of activated carbon and iron/cerium modified activated carbon to remove methylene blue from wastewater.

    PubMed

    Cheng, Song; Zhang, Libo; Ma, Aiyuan; Xia, Hongying; Peng, Jinhui; Li, Chunyang; Shu, Jianhua

    2018-03-01

    The methylene blue (MB) removal abilities of raw activated carbon and iron/cerium modified raw activated carbon (Fe-Ce-AC) by adsorption were researched and compared. The characteristics of Fe-Ce-AC were examined by N 2 adsorption, zeta potential measurement, FTIR, Raman, XRD, XPS, SEM and EDS. After modification, the following phenomena occurred: The BET surface area, average pore diameter and total pore volume decreased; the degree of graphitization also decreased. Moreover, the presence of Fe 3 O 4 led to Fe-Ce-AC having magnetic properties, which makes it easy to separate from dye wastewater in an external magnetic field and subsequently recycle. In addition, the equilibrium isotherms and kinetics of MB adsorption on raw activated carbon and Fe-Ce-AC were systematically examined. The equilibrium adsorption data indicated that the adsorption behavior followed the Langmuir isotherm, and the pseudo-second-order model matched the kinetic data well. Compared with raw activated carbon, the maximum monolayer adsorption capacity of Fe-Ce-AC increased by 27.31%. According to the experimental results, Fe-Ce-AC can be used as an effective adsorbent for the removal of MB from dye wastewater. Copyright © 2017. Published by Elsevier B.V.

  12. Source contributions to black carbon mass fractions in aerosol particles over the northwestern Pacific

    NASA Astrophysics Data System (ADS)

    Koga, Seizi; Maeda, Takahisa; Kaneyasu, Naoki

    Aerosol particle number size distributions above 0.3 μm in diameter and black carbon mass concentrations in aerosols were observed on Chichi-jima of the Ogasawara Islands in the northwestern Pacific from January 2000 to December 2002. Chichi-jima is suitable to observe polluted air masses from East Asia in winter and clean air masses over the western North Pacific in summer. In winter, aerosols over Chichi-jima were strongly affected by anthropogenic emissions in East Asia. The form of energy consumption in East Asia varies in various regions. Hence, each source region is expected to be characterized by an individual black carbon mass fraction. A three-dimensional Eulerian transport model was used to estimate contribution rates to air pollutants from each source region in East Asia. Because the Miyake-jima eruption began at the end of June 2000, the influence of smokes from Miyake-jima was also considered in the model calculation. The results of model calculations represent what must be noticed about smokes from volcanoes including Miyake-jima to interpret temporal variations of sulfur compounds over the northwestern Pacific. To evaluate black carbon mass fractions in anthropogenic aerosols as a function of source region, the relationships between the volume concentration of aerosol particles and the black carbon mass concentration in the winter were classified under each source region in East Asia. Consequently, the black carbon mass fractions in aerosols from China, Japan and the Korean Peninsula, and other regions were estimated to be 9-13%, 5-7%, and 4-5%, respectively.

  13. Vascular effects of ultrafine particles in persons with type 2 diabetes

    EPA Science Inventory

    BACKGROUND: Diabetes confers an increased risk for cardiovascular effects of airborne particles. OBJECTIVE: We hypothesized that inhalation of elemental carbon ultrafine particles (UFP) would activate blood platelets and vascular endothelium in people with type 2 diabetes. ...

  14. Study of CO2 adsorption capacity of mesoporous carbon and activated carbon modified by triethylenetetramine (TETA)

    NASA Astrophysics Data System (ADS)

    Sulistianti, I.; Krisnandi, Y. K.; Moenandar, I.

    2017-04-01

    Mesoporous carbon was synthesized by soft template method using phloroglucinol and formaldehyde as a carbon source; and Pluronic F-127 as a mesoporous template. The synthesized mesoporous carbon and commercial activated carbon were modified with triethylenetetramine (TETA) to increase CO2 adsorption capacity. Based on FTIR characterization, the synthesized mesoporous carbon and the activated carbon without modification process has similarity pattern. After the modification, both of them showed absorption peaks in the area around 1580 to 1650 cm-1 which is known as N-H bending vibration and absorption peaks in the area around 3150 to 3380 cm-1 which is known as N-H stretching vibration. The XRD results showed two peaks at 2θ = 24.21° and 2θ = 43.85°, according to JCPDS index No. 75-1621 those peak are the typical peaks for hexagonal graphite carbon. In BET analysis, the synthesized mesoporous carbon and activated carbon modified TETA have surface area, pore volume and pore diameter lower than without modification process. In carbon dioxide adsorption testing, the synthesized mesoporous carbon showed better performance than the commercial activated carbon for CO2 adsorption both without modification and by modification. The synthesized mesoporous carbon obtained CO2 adsorption of 9.916 mmol/g and the activated carbon of 3.84 mmol/g for on 3.5 hours of adsorption. It is three times better than activated carbon for adsorption of carbon dioxide. The modified mesoporous carbon has the best performance for adsorption of gas CO2 if compared by unmodified.

  15. Optofluidics incorporating actively controlled micro- and nano-particles

    PubMed Central

    Kayani, Aminuddin A.; Khoshmanesh, Khashayar; Ward, Stephanie A.; Mitchell, Arnan; Kalantar-zadeh, Kourosh

    2012-01-01

    The advent of optofluidic systems incorporating suspended particles has resulted in the emergence of novel applications. Such systems operate based on the fact that suspended particles can be manipulated using well-appointed active forces, and their motions, locations and local concentrations can be controlled. These forces can be exerted on both individual and clusters of particles. Having the capability to manipulate suspended particles gives users the ability for tuning the physical and, to some extent, the chemical properties of the suspension media, which addresses the needs of various advanced optofluidic systems. Additionally, the incorporation of particles results in the realization of novel optofluidic solutions used for creating optical components and sensing platforms. In this review, we present different types of active forces that are used for particle manipulations and the resulting optofluidic systems incorporating them. These systems include optical components, optofluidic detection and analysis platforms, plasmonics and Raman systems, thermal and energy related systems, and platforms specifically incorporating biological particles. We conclude the review with a discussion of future perspectives, which are expected to further advance this rapidly growing field. PMID:23864925

  16. System and method for coproduction of activated carbon and steam/electricity

    DOEpatents

    Srinivasachar, Srivats [Sturbridge, MA; Benson, Steven [Grand Forks, ND; Crocker, Charlene [Newfolden, MN; Mackenzie, Jill [Carmel, IN

    2011-07-19

    A system and method for producing activated carbon comprising carbonizing a solid carbonaceous material in a carbonization zone of an activated carbon production apparatus (ACPA) to yield a carbonized product and carbonization product gases, the carbonization zone comprising carbonaceous material inlet, char outlet and carbonization gas outlet; activating the carbonized product via activation with steam in an activation zone of the ACPA to yield activated carbon and activation product gases, the activation zone comprising activated carbon outlet, activation gas outlet, and activation steam inlet; and utilizing process gas comprising at least a portion of the carbonization product gases or a combustion product thereof; at least a portion of the activation product gases or a combustion product thereof; or a combination thereof in a solid fuel boiler system that burns a solid fuel boiler feed with air to produce boiler-produced steam and flue gas, the boiler upstream of an air heater within a steam/electricity generation plant, said boiler comprising a combustion zone, a boiler-produced steam outlet and at least one flue gas outlet.

  17. Porous properties of activated carbons from waste newspaper prepared by chemical and physical activation.

    PubMed

    Okada, Kiyoshi; Yamamoto, Nobuo; Kameshima, Yoshikazu; Yasumori, Atsuo

    2003-06-01

    Activated carbons were prepared from old newspaper and paper prepared from simulated paper sludge by chemical activation using various alkali carbonates and hydroxides as activating reagents and also by physical activation using steam. In the chemical activation, the influence of oxidation, carbonization, and activation on the porous properties of the resulting activated carbons was investigated. The specific surface areas (S(BET)) of the activated carbons prepared by single-step activation (direct activation without oxidation and carbonization) were higher than those resulting from two-step activation (oxidation-activation and carbonization-activation) and three-step activation (oxidation-carbonization-activation) methods. The S(BET) values were strongly dependent on the activating reagents and the activating conditions, being >1000 m(2)/g using K(2)CO(3), Rb(2)CO(3), Cs(2)CO(3), and KOH as activating reagents but <1000 m(2)/g using Li(2)CO(3), Na(2)CO(3), and NaOH. These differences in S(BET) values are suggested to be related to the ionic radii of the alkalis used as activating reagents. The microstructures of the higher S(BET) samples show a complete loss of fiber shape but those of the lower S(BET) samples maintain the shape. In the physical activation, the porous properties of the activated carbons prepared by the single-step method were examined as a function of the production conditions such as activation temperature, activation time, steam concentration, and flow rate of the carrier gas. The maximum S(BET) and total pore volume (V(P)) were 1086 m(2)/g and 1.01 ml/g, obtained by activation at 850 degrees C for 2 h, flowing 20 mol% of steam in nitrogen gas at 0.5 l/min. A correlation was found between S(BET) and the yield of the product, the maximum S(BET) value corresponding to a product yield of about 10%. This result is suggested to result from competition between pore formation and surface erosion. Compared with chemically activated carbons using K(2)CO

  18. Self-assembly of active amphiphilic Janus particles

    NASA Astrophysics Data System (ADS)

    Mallory, S. A.; Alarcon, F.; Cacciuto, A.; Valeriani, C.

    2017-12-01

    In this article, we study the phenomenology of a two dimensional dilute suspension of active amphiphilic Janus particles. We analyze how the morphology of the aggregates emerging from their self-assembly depends on the strength and the direction of the active forces. We systematically explore and contrast the phenomenologies resulting from particles with a range of attractive patch coverages. Finally, we illustrate how the geometry of the colloids and the directionality of their interactions can be used to control the physical properties of the assembled active aggregates and suggest possible strategies to exploit self-propulsion as a tunable driving force for self-assembly.

  19. Time-resolved analysis of particle emissions from residential biomass combustion - Emissions of refractory black carbon, PAHs and organic tracers

    NASA Astrophysics Data System (ADS)

    Nielsen, Ingeborg E.; Eriksson, Axel C.; Lindgren, Robert; Martinsson, Johan; Nyström, Robin; Nordin, Erik Z.; Sadiktsis, Ioannis; Boman, Christoffer; Nøjgaard, Jacob K.; Pagels, Joakim

    2017-09-01

    Time-resolved particle emissions from a conventional wood stove were investigated with aerosol mass spectrometry to provide links between combustion conditions, emission factors, mixing state of refractory black carbon and implications for organic tracer methods. The addition of a new batch of fuel results in low temperature pyrolysis as the fuel heats up, resulting in strong, short-lived, variable emission peaks of organic aerosol-containing markers of anhydrous sugars, such as levoglucosan (fragment at m/z 60). Flaming combustion results in emissions dominated by refractory black carbon co-emitted with minor fractions of organic aerosol and markers of anhydrous sugars. Full cycle emissions are an external mixture of larger organic aerosol-dominated and smaller thinly coated refractory black carbon particles. A very high burn rate results in increased full cycle mass emission factors of 66, 2.7, 2.8 and 1.3 for particulate polycyclic aromatic hydrocarbons, refractory black carbon, total organic aerosol and m/z 60, respectively, compared to nominal burn rate. Polycyclic aromatic hydrocarbons are primarily associated with refractory black carbon-containing particles. We hypothesize that at very high burn rates, the central parts of the combustion zone become air starved, leading to a locally reduced combustion temperature that reduces the conversion rates from polycyclic aromatic hydrocarbons to refractory black carbon. This facilitates a strong increase of polycyclic aromatic hydrocarbons emissions. At nominal burn rates, full cycle emissions based on m/z 60 correlate well with organic aerosol, refractory black carbon and particulate matter. However, at higher burn rates, m/z 60 does not correlate with increased emissions of polycyclic aromatic hydrocarbons, refractory black carbon and organic aerosol in the flaming phase. The new knowledge can be used to advance source apportionment studies, reduce emissions of genotoxic compounds and model the climate impacts of

  20. Transport of underdamped active particles in ratchet potentials.

    PubMed

    Ai, Bao-Quan; Li, Feng-Guo

    2017-03-29

    We study the rectified transport of underdamped active noninteracting particles in an asymmetric periodic potential. It is found that the ratchet effect of active noninteracting particles occurs in a single direction (along the easy direction of the substrate asymmetry) in the overdamped limit. However, when the inertia is considered, it is possible to observe reversals of the ratchet effect, where the motion is along the hard direction of the substrate asymmetry. By changing the friction coefficient or the self-propulsion force, the average velocity can change its direction several times. Therefore, by suitably tailoring the parameters, underdamped active particles with different self-propulsion forces can move in different directions and can be separated.

  1. ENTRAINED-FLOW ADSORPTION OF MERCURY USING ACTIVATED CARBON

    EPA Science Inventory

    Bench-scale experiments were conducted in a flow reactor to simulate entrained-flow capture of elemental mercury (Hg) by activated carbon. Adsorption of Hg by several commercial activated carbons was examined at different carbon-to-mercury (C:Hg) ratios (by weight) (600:1 - 29000...

  2. The adsorption of pharmaceutically active compounds from aqueous solutions onto activated carbons.

    PubMed

    Rakić, Vesna; Rac, Vladislav; Krmar, Marija; Otman, Otman; Auroux, Aline

    2015-01-23

    In this study, the adsorption of pharmaceutically active compounds - salicylic acid, acetylsalicylic acid, atenolol and diclofenac-Na onto activated carbons has been studied. Three different commercial activated carbons, possessing ∼650, 900 or 1500m(2)g(-1) surface areas were used as solid adsorbents. These materials were fully characterized - their textural, surface features and points of zero charge have been determined. The adsorption was studied from aqueous solutions at 303K using batch adsorption experiments and titration microcalorimetry, which was employed in order to obtain the heats evolved as a result of adsorption. The maximal adsorption capacities of investigated solids for all target pharmaceuticals are in the range of 10(-4)molg(-1). The obtained maximal retention capacities are correlated with the textural properties of applied activated carbon. The roles of acid/base features of activated carbons and of molecular structures of adsorbate molecules have been discussed. The obtained results enabled to estimate the possibility to use the activated carbons in the removal of pharmaceuticals by adsorption. Copyright © 2014 Elsevier B.V. All rights reserved.

  3. Apparatus for producing carbon-coated nanoparticles and carbon nanospheres

    DOEpatents

    Perry, W. Lee; Weigle, John C.; Phillips, Jonathan

    2015-10-20

    An apparatus for producing carbon-coated nano- or micron-scale particles comprising a container for entraining particles in an aerosol gas, providing an inlet for carbon-containing gas, providing an inlet for plasma gas, a proximate torch for mixing the aerosol gas, the carbon-containing gas, and the plasma gas, bombarding the mixed gases with microwaves, and providing a collection device for gathering the resulting carbon-coated nano- or micron-scale particles. Also disclosed is a method and apparatus for making hollow carbon nano- or micro-scale spheres.

  4. Enhanced photocatalytic activity of Fe-doped TiO2 coated on N-doped activated carbon composites for photocatalytic degradation of dyeing wastewater

    NASA Astrophysics Data System (ADS)

    Zhou, Jie; Zhu, Beibei; Wang, Lu; Li, Ya; Qiao, Qichen

    2017-10-01

    Fe-doped TiO2 coated on N-doped activated carbon (Fe-TiO2/N-AC, FTNA) composites were synthesized simply by a straightforward two-step procedure. The obtained materials were characterized by X-ray diffractometry (XRD), N2 adsorption-desorption, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and FT-IR spectroscopies. Through the degradation of dyeing wastewater, the photocatalytic activity of FTNA was investigated under ultraviolet light irradiation. The results showed that containing N functional groups were successfully introduced onto the surface of the activated carbon. Compared with Fe-TiO2/AC (FTA), FTNA with average particle size of TiO2 13.6 nm and surface area 1007.89 m2/g showed a higher photoactivity. Additionally, for the photocatalytic degradation of dyeing wastewater, the optimum N content and catalyst content were 0.8% and 5g/L, respectively. Moreover, the photoactivity and photo stability of the catalyst after many runs was also evaluated.

  5. Natural sisal fibers derived hierarchical porous activated carbon as capacitive material in lithium ion capacitor

    NASA Astrophysics Data System (ADS)

    Yang, Zhewei; Guo, Huajun; Li, Xinhai; Wang, Zhixing; Yan, Zhiliang; Wang, Yansen

    2016-10-01

    Lithium-ion capacitor (LIC) is a novel advanced electrochemical energy storage (EES) system bridging gap between lithium ion battery (LIB) and electrochemical capacitor (ECC). In this work, we report that sisal fiber activated carbon (SFAC) was synthesized by hydrothermal treatment followed by KOH activation and served as capacitive material in LIC for the first time. Different particle structure, morphology, specific surface area and heteroatoms affected the electrochemical performance of as-prepared materials and corresponding LICs. When the mass ratio of KOH to char precursor was 2, hierarchical porous structured SFAC-2 was prepared and exhibited moderate specific capacitance (103 F g-1 at 0.1 A g-1), superior rate capability and cyclic stability (88% capacity retention after 5000 cycles at 1 A g-1). The corresponding assembled LIC (LIC-SC2) with optimal comprehensive electrochemical performance, displayed the energy density of 83 Wh kg-1, the power density of 5718 W kg-1 and superior cyclic stability (92% energy density retention after 1000 cycles at 0.5 A g-1). It is worthwhile that the source for activated carbon is a natural and renewable one and the synthesis method is eco-friendly, which facilitate that hierarchical porous activated carbon has potential applications in the field of LIC and other energy storage systems.

  6. Production of activated carbon from rice husk Vietnam

    NASA Astrophysics Data System (ADS)

    Korobochkin, V. V.; Tu, N. V.; Hieu, N. M.

    2016-09-01

    This work is dedicated to the production of activated carbon from rice husk from Delta of the Red River in Viet Nam. At the first stage, carbonization of a rice husk was carried out to obtain material containing 43.1% carbon and 25 % silica with a specific surface area of 51.5 m2/g. After separating of silica (the second stage), the specific surface area of the product increased to 204 m2/g and the silica content decreased to 1.23% by weight as well. The most important stage in the formation of the porous structure of the material is the activation. The products with the high specific surface area in the range of 800-1345 m2/g were obtained by activation of carbonized product with water vapour or carbon dioxide at temperatures of 700 °C and 850 °C, with varying the flow rate of the activating agent and activation time. The best results were achieved by activation of carbon material with water vapour at the flow rate of 0.08 dm3/min per 500 g of material and the temperature of 850 °C.

  7. Enhancing hydrogen storage performances of MgH2 by Ni nano-particles over mesoporous carbon CMK-3.

    PubMed

    Chen, Gang; Zhang, Yao; Chen, Jian; Guo, Xinli; Zhu, Yunfeng; Li, Liquan

    2018-06-29

    Nano-dispersed Ni particles over mesoporous carbon material CMK-3 (Ni/CMK-3) was fabricated by means of impregnation-reduction strategy using precursor NiCl 2  · 6H 2 O, which is beneficial to improving the de/rehydrogenation performances of MgH 2 . The dehydrogenation onset temperature of MgH 2 -Ni/CMK-3 is significantly lowered by 170 K from that of pristine MgH 2 (around 603 K). Totally 5.9 wt% of hydrogen absorption capacity is liberated within 1 h at a temperature of 423 K under a pressure of 3 MPa. This composite can absorb 3.9 wt% hydrogen even at a temperature of 328 K under 3 MPa H 2 . Activation energy values of both dehydrogenation (43.4 kJ mol -1 ) and rehydrogenation (37.4 kJ mol -1 ) for MgH 2 -Ni/CMK-3 are greatly enhanced from those of as-milled MgH 2 . Ni/CMK-3 also slightly destabilizes the dehydrogenation of MgH 2 by 1.5 kJ mol [Formula: see text] The enhanced performances can be attributed to the synergistic effects of both destabilization and activation from nano-dispersed Ni particles.

  8. Enhancing hydrogen storage performances of MgH2 by Ni nano-particles over mesoporous carbon CMK-3

    NASA Astrophysics Data System (ADS)

    Chen, Gang; Zhang, Yao; Chen, Jian; Guo, Xinli; Zhu, Yunfeng; Li, Liquan

    2018-06-01

    Nano-dispersed Ni particles over mesoporous carbon material CMK-3 (Ni/CMK-3) was fabricated by means of impregnation-reduction strategy using precursor NiCl2 · 6H2O, which is beneficial to improving the de/rehydrogenation performances of MgH2. The dehydrogenation onset temperature of MgH2–Ni/CMK-3 is significantly lowered by 170 K from that of pristine MgH2 (around 603 K). Totally 5.9 wt% of hydrogen absorption capacity is liberated within 1 h at a temperature of 423 K under a pressure of 3 MPa. This composite can absorb 3.9 wt% hydrogen even at a temperature of 328 K under 3 MPa H2. Activation energy values of both dehydrogenation (43.4 kJ mol‑1) and rehydrogenation (37.4 kJ mol‑1) for MgH2–Ni/CMK-3 are greatly enhanced from those of as-milled MgH2. Ni/CMK-3 also slightly destabilizes the dehydrogenation of MgH2 by 1.5 kJ mol {{{{H}}}2}-1. The enhanced performances can be attributed to the synergistic effects of both destabilization and activation from nano-dispersed Ni particles.

  9. Activated carbon-supported CuO nanoparticles: a hybrid material for carbon dioxide adsorption

    NASA Astrophysics Data System (ADS)

    Boruban, Cansu; Esenturk, Emren Nalbant

    2018-03-01

    Activated carbon-supported copper(II) oxide (CuO) nanoparticles were synthesized by simple impregnation method to improve carbon dioxide (CO2) adsorption capacity of the support. The structural and chemical properties of the hybrid material were characterized by scanning electron microscopy (SEM), energy dispersive X-ray (EDX), X-ray diffraction (https://www.google.com.tr/url?sa=t&rct=j&q=&esrc=s&source=web&cd=3&cad=rja&uact=8&ved=0CCsQFjAC&url=http%3A%2F%2Fwww.intertek.com%2Fanalytical-laboratories%2Fxrd%2F&ei=-5WZVYSCHISz7Aatqq-IAw&usg=AFQjCNFBlk-9wqy49foh8tskmbD-GGbG9g&sig2=eKrhYjO75rl_Id2sLGpq4w&bvm=bv.96952980,d.bGg) (XRD), X-ray photoelectron spectroscopy (XPS), atomic absorption spectroscopy (AAS), and Brunauer-Emmett-Teller (BET) analyses. The analyses showed that CuO nanoparticles are well-distributed on the activated carbon surface. The CO2 adsorption behavior of the activated carbon-supported CuO nanoparticles was observed by thermogravimetric analysis (TGA), temperature programmed desorption (TPD), Fourier transform infrared (FTIR), and BET analyses. The results showed that CuO nanoparticle loading on activated carbon led to about 70% increase in CO2 adsorption capacity of activated carbon under standard conditions (1 atm and 298 K). The main contributor to the observed increase is an improvement in chemical adsorption of CO2 due to the presence of CuO nanoparticles on activated carbon.

  10. Organic solvent regeneration of granular activated carbon

    NASA Astrophysics Data System (ADS)

    Cross, W. H.; Suidan, M. T.; Roller, M. A.; Kim, B. R.; Gould, J. P.

    1982-09-01

    The use of activated carbon for the treatment of industrial waste-streams was shown to be an effective treatment. The high costs associated with the replacement or thermal regeneration of the carbon have prohibited the economic feasibility of this process. The in situ solvent regeneration of activated carbon by means of organic solvent extraction was suggested as an economically alternative to thermal regeneration. The important aspects of the solvent regeneration process include: the physical and chemical characteristics of the adsorbent, the pore size distribution and energy of adsorption associated with the activated carbon; the degree of solubility of the adsorbate in the organic solvent; the miscibility of the organic solvent in water; and the temperature at which the generation is performed.

  11. Hysteretic dynamics of active particles in a periodic orienting field

    PubMed Central

    Romensky, Maksym; Scholz, Dimitri; Lobaskin, Vladimir

    2015-01-01

    Active motion of living organisms and artificial self-propelling particles has been an area of intense research at the interface of biology, chemistry and physics. Significant progress in understanding these phenomena has been related to the observation that dynamic self-organization in active systems has much in common with ordering in equilibrium condensed matter such as spontaneous magnetization in ferromagnets. The velocities of active particles may behave similar to magnetic dipoles and develop global alignment, although interactions between the individuals might be completely different. In this work, we show that the dynamics of active particles in external fields can also be described in a way that resembles equilibrium condensed matter. It follows simple general laws, which are independent of the microscopic details of the system. The dynamics is revealed through hysteresis of the mean velocity of active particles subjected to a periodic orienting field. The hysteresis is measured in computer simulations and experiments on unicellular organisms. We find that the ability of the particles to follow the field scales with the ratio of the field variation period to the particles' orientational relaxation time, which, in turn, is related to the particle self-propulsion power and the energy dissipation rate. The collective behaviour of the particles due to aligning interactions manifests itself at low frequencies via increased persistence of the swarm motion when compared with motion of an individual. By contrast, at high field frequencies, the active group fails to develop the alignment and tends to behave like a set of independent individuals even in the presence of interactions. We also report on asymptotic laws for the hysteretic dynamics of active particles, which resemble those in magnetic systems. The generality of the assumptions in the underlying model suggests that the observed laws might apply to a variety of dynamic phenomena from the motion of

  12. Bioavailable Carbon and the Relative Degradation State of Organic Matter in Active Layer and Permafrost Soils

    NASA Astrophysics Data System (ADS)

    Jastrow, J. D.; Burke, V. J.; Vugteveen, T. W.; Fan, Z.; Hofmann, S. M.; Lederhouse, J. S.; Matamala, R.; Michaelson, G. J.; Mishra, U.; Ping, C. L.

    2015-12-01

    The decomposability of soil organic carbon (SOC) in permafrost regions is a key uncertainty in efforts to predict carbon release from thawing permafrost and its impacts. The cold and often wet environment is the dominant factor limiting decomposer activity, and soil organic matter is often preserved in a relatively undecomposed and uncomplexed state. Thus, the impacts of soil warming and permafrost thaw are likely to depend at least initially on the genesis and past history of organic matter degradation before its stabilization in permafrost. We compared the bioavailability and relative degradation state of SOC in active layer and permafrost soils from Arctic tundra in Alaska. To assess readily bioavailable SOC, we quantified salt (0.5 M K2SO4) extractable organic matter (SEOM), which correlates well with carbon mineralization rates in short-term soil incubations. To assess the relative degradation state of SOC, we used particle size fractionation to isolate fibric (coarse) from more degraded (fine) particulate organic matter (POM) and separated mineral-associated organic matter into silt- and clay-sized fractions. On average, bulk SOC concentrations in permafrost were lower than in comparable active layer horizons. Although SEOM represented a very small proportion of the bulk SOC, this proportion was greater in permafrost than in comparable active layer soils. A large proportion of bulk SOC was found in POM for all horizons. Even for mineral soils, about 40% of bulk SOC was in POM pools, indicating that organic matter in both active layer and permafrost mineral soils was relatively undecomposed compared to typical temperate soils. Not surprisingly, organic soils had a greater proportion of POM and mineral soils had greater silt- and clay-sized carbon pools, while cryoturbated soils were intermediate. For organic horizons, permafrost organic matter was generally more degraded than in comparable active layer horizons. However, in mineral and cryoturbated horizons

  13. Design of activated carbon/activated carbon asymmetric capacitors

    NASA Astrophysics Data System (ADS)

    Piñeiro-Prado, Isabel; Salinas-Torres, David; Ruiz Rosas, Ramiro; Morallon, Emilia; Cazorla-Amoros, Diego

    2016-03-01

    Supercapacitors are energy storage devices that offer a high power density and a low energy density in comparison with batteries. Their limited energy density can be overcome by using asymmetric configuration in mass electrodes, where each electrode works within their maximum available potential window, rendering the maximum voltage output of the system. Such asymmetric capacitors must be optimized through careful electrochemical characterization of the electrodes for accurate determination of the capacitance and the potential stability limits. The results of the characterization are then used for optimizing mass ratio of the electrodes from the balance of stored charge. The reliability of the design largely depends on the approach taken for the electrochemical characterization. Therefore, the performance could be lower than expected and even the system could break down, if a well thought out procedure is not followed. In this work, a procedure for the development of asymmetric supercapacitors based on activated carbons is detailed. Three activated carbon materials with different textural properties and surface chemistry have been systematically characterized in neutral aqueous electrolyte. The asymmetric configuration of the masses of both electrodes in the supercapacitor has allowed to cover a higher potential window, resulting in an increase of the energy density of the three devices studied when compared with the symmetric systems, and an improved cycle life.

  14. Modified Activated Carbon Perchlorate Sorbents

    DTIC Science & Technology

    2007-01-25

    Yield 4.64 g. Methyl Chloride Alkylated Activated Carbon Methyl chloride (MeCl) treatment was carried out in a tube furnace generally in...with alkylation agents lowers the solution pH as the basic sites are alkylated . In the case of Me2SO4 treatment , the low slurry pH is believed to be...by Cannon and coworkers, the alkylated carbons are not significantly better. In the case of the SAI carbons, ammonia treatment does not result in a

  15. Carbon monoxide and methane adsorption of crude oil refinery using activated carbon from palm shells as biosorbent

    NASA Astrophysics Data System (ADS)

    Yuliusman; Afdhol, M. K.; Sanal, Alristo

    2018-03-01

    Carbon monoxide and methane gas are widely present in oil refineries. Off-potential gas is used as raw material for the petrochemical industry. In order for this off-gas to be utilized, carbon monoxide and methane must be removed from off-gas. This study aims to adsorb carbon monoxide and methane using activated carbon of palm shells and commercial activated carbon simultaneously. This research was conducted in 2 stages: 1) Preparation and characterization of activated carbon, 2) Carbon monoxide and methane adsorption test. The activation experiments using carbon dioxide at a flow rate of 150 ml/min yielded a surface area of 978.29 m2/g, Nitrogen at flow rate 150 ml/min yielded surface area 1241.48 m2/g, and carbon dioxide and nitrogen at a flow rate 200 ml/min yielded a surface area 300.37 m2/g. Adsorption of carbon monoxide and methane on activated carbon of palm shell systems yielded results in the amount of 0.5485 mg/g and 0.0649 mg/g and using commercial activated carbon yielded results in the amount of 0.5480 mg/g and 0.0650 mg/g

  16. Microfluidic rheology of active particle suspensions: Kinetic theory

    NASA Astrophysics Data System (ADS)

    Alonso-Matilla, Roberto; Ezhilan, Barath; Saintillan, David

    2016-11-01

    We analyze the effective rheology of a dilute suspension of self-propelled slender particles between two infinite parallel plates in a pressure-driven flow. We use a continuum kinetic model to study the dynamics and transport of particles, where hydrodynamic interactions induced by the swimmers are taken into account. Using finite volume simulations we study how the activity of the swimmer and the external flow modify the rheological properties of the system. Results indicate that at low flow rates, activity decreases the value of the viscosity for pushers and increases its value for pullers. Both effects become weaker with increasing the flow strength due to the alignment of the particles with the flow. In the case of puller particles, shear thinning is observed over the entire range of flow rates. Pusher particles exhibit shear thickening at intermediate flow rates, where passive stresses start dominating over active stresses, reaching a viscosity greater than that of the Newtonian fluid. Finally shear thinning is observed at high flow rates. Both pushers and pullers exhibit a Newtonian plateau at very high flow rates. We demonstrate a good agreement between numerical results and experiments.

  17. Computer simulation of the carbon activity in austenite

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Murch, G.E.; Thorn, R.J.

    1979-02-01

    Carbon activity in austenite is described in terms of an Ising-like f.c.c. lattice gas model in which carbon interstitials repel only at the distance of nearest neighbors. A Monte Carlo simulation method in the petit canonical ensemble is employed to calculate directly the carbon activity as a function of composition and temperature. The computed activities are in satisfactory agreement with the experimental data, similarly for the decompostion of the activity to the partial molar enthalpy and entropy.

  18. Carbon Nanotubes Released from an Epoxy-Based Nanocomposite: Quantification and Particle Toxicity.

    PubMed

    Schlagenhauf, Lukas; Buerki-Thurnherr, Tina; Kuo, Yu-Ying; Wichser, Adrian; Nüesch, Frank; Wick, Peter; Wang, Jing

    2015-09-01

    Studies combining both the quantification of free nanoparticle release and the toxicological investigations of the released particles from actual nanoproducts in a real-life exposure scenario are urgently needed, yet very rare. Here, a new measurement method was established to quantify the amount of free-standing and protruding multiwalled carbon nanotubes (MWCNTs) in the respirable fraction of particles abraded from a MWCNT-epoxy nanocomposite. The quantification approach involves the prelabeling of MWCNTs with lead ions, nanocomposite production, abrasion and collection of the inhalable particle fraction, and quantification of free-standing and protruding MWCNTs by measuring the concentration of released lead ions. In vitro toxicity studies for genotoxicity, reactive oxygen species formation, and cell viability were performed using A549 human alveolar epithelial cells and THP-1 monocyte-derived macrophages. The quantification experiment revealed that in the respirable fraction of the abraded particles, approximately 4000 ppm of the MWCNTs were released as exposed MWCNTs (which could contact lung cells upon inhalation) and approximately 40 ppm as free-standing MWCNTs in the worst-case scenario. The release of exposed MWCNTs was lower for nanocomposites containing agglomerated MWCNTs. The toxicity tests revealed that the abraded particles did not induce any acute cytotoxic effects.

  19. Unburnt carbon from coal fly ashes as a precursor of activated carbon for nitric oxide removal.

    PubMed

    Rubio, Begoña; Izquierdo, M Teresa; Mayoral, M Carmen; Bona, M Teresa; Andres, Jose M

    2007-05-08

    The aim of this work is to evaluate the characteristics of an activated carbon obtained from unburnt carbon in coal fly ashes to be used in the removal of NO. Carbon-rich fraction was obtained by mechanical sieving of fly ashes. The mineral matter was removed by conventional HCl and HF demineralization procedure. Activation was carried out with steam at 900 degrees C in order to develop porosity onto the sample. Characterization of samples was performed by several techniques with a main objective: to follow the mineral matter content, composition and distribution on the samples in order to better understand how to remove it from unburnt carbon in fly ashes. To study the use of this unburnt carbon as a precursor for the preparation of activated carbons for gas cleaning, the NO removal by ammonia using activated carbon as a catalyst at low temperature was performed. Results show a good performance of activated carbon in this reaction that is in relationship with BET surface area.

  20. Isolation and Quantitative Estimation of Diesel Exhaust and Carbon Black Particles Ingested by Lung Epithelial Cells and Alveolar Macrophages In Vitro

    EPA Science Inventory

    A new procedure for isolating and estimating ingested carbonaceous diesel exhaust particles (DEP) or carbon black (CB) particles by lung epithelial cells and macrophages is described. Cells were incubated with DEP or CB to examine cell-particle interaction and ingestion. After va...

  1. Measurement of Biocolloid Collision Efficiencies for Granular Activated Carbon by Use of a Two-Layer Filtration Model

    PubMed Central

    Paramonova, Ekaterina; Zerfoss, Erica L.; Logan, Bruce E.

    2006-01-01

    Point-of-use filters containing granular activated carbon (GAC) are an effective method for removing certain chemicals from water, but their ability to remove bacteria and viruses has been relatively untested. Collision efficiencies (α) were determined using clean-bed filtration theory for two bacteria (Raoutella terrigena 33257 and Escherichia coli 25922), a bacteriophage (MS2), and latex microspheres for four GAC samples. These GAC samples had particle size distributions that were bimodal, but only a single particle diameter can be used in the filtration equation. Therefore, consistent with previous reports, we used a particle diameter based on the smallest diameter of the particles (derived from the projected areas of 10% of the smallest particles). The bacterial collision efficiencies calculated using the filtration model were high (0.8 ≤ α ≤ 4.9), indicating that GAC was an effective capture material. Collision efficiencies greater than unity reflect an underestimation of the collision frequency, likely as a result of particle roughness and wide GAC size distributions. The collision efficiencies for microspheres (0.7 ≤ α ≤ 3.5) were similar to those obtained for bacteria, suggesting that the microspheres were a reasonable surrogate for the bacteria. The bacteriophage collision efficiencies ranged from ≥0.2 to ≤0.4. The predicted levels of removal for 1-cm-thick carbon beds ranged from 0.8 to 3 log for the bacteria and from 0.3 to 1.0 log for the phage. These tests demonstrated that GAC can be an effective material for removal of bacteria and phage and that GAC particle size is a more important factor than relative stickiness for effective particle removal. PMID:16885264

  2. Springtime carbon emission episodes at the Gosan background site revealed by total carbon, stable carbon isotopic composition, and thermal characteristics of carbonaceous particles

    NASA Astrophysics Data System (ADS)

    Jung, J.; Kawamura, K.

    2011-11-01

    In order to investigate the emission of carbonaceous aerosols at the Gosan background super-site (33.17° N, 126.10° E) in East Asia, total suspended particles (TSP) were collected during spring of 2007 and 2008 and analyzed for particulate organic carbon, elemental carbon, total carbon (TC), total nitrogen (TN), and stable carbon isotopic composition (δ13C) of TC. The stable carbon isotopic composition of TC (δ13CTC) was found to be lowest during pollen emission episodes (range: -26.2‰ to -23.5‰, avg. -25.2 ± 0.9‰), approaching those of the airborne pollen (-28.0‰) collected at the Gosan site. Based on a carbon isotope mass balance equation, we found that ~42% of TC in the TSP samples during the pollen episodes was attributed to airborne pollen from Japanese cedar trees planted around tangerine farms in Jeju Island. A negative correlation between the citric acid-carbon/TC ratios and δ13CTC was obtained during the pollen episodes. These results suggest that citric acid emitted from tangerine fruit may be adsorbed on the airborne pollen and then transported to the Gosan site. Thermal evolution patterns of organic carbon during the pollen episodes were characterized by high OC evolution in the OC2 temperature step (450 °C). Since thermal evolution patterns of organic aerosols are highly influenced by their molecular weight, they can be used as additional information on the formation of secondary organic aerosols and the effect of aging of organic aerosols during the long-range atmospheric transport and sources of organic aerosols.

  3. Synthesis of a Carbon-activated Microfiber from Spider Webs Silk

    NASA Astrophysics Data System (ADS)

    Taer, E.; Mustika, W. S.; Taslim, R.

    2017-03-01

    Carbon fiber of spider web silk has been produced through the simple carbonization process. Cobwebs are a source of strong natural fiber, flexible and micrometer in size. Preparation of micro carbon fiber from spider webs that consist of carbonization and activation processes. Carbonization was performed in N2 gas environment by multi step heating profile up to temperature of 400 °C, while the activation process was done by using chemical activation with KOH activating agent assistance. Measurement of physical properties was conducted on the surface morphology, element content and the degree of crystallinity. The measurement results found that micro carbon fiber from spider webs has a diameter in the range of 0.5 -25 micrometers. It is found that the carbon-activated microfiber takes the amorphous form with the carbon content of 84 %.

  4. Carbon Dioxide Capture by Deep Eutectic Solvent Impregnated Sea Mango Activated Carbon

    NASA Astrophysics Data System (ADS)

    Zulkurnai, N. Z.; Ali, U. F. Md.; Ibrahim, N.; Manan, N. S. Abdul

    2018-03-01

    The increment amount of the CO2 emission by years has become a major concern worldwide due to the global warming issue. However, the influence modification of activated carbon (AC) has given a huge revolution in CO2 adsorption capture compare to the unmodified AC. In the present study, the Deep Eutectic Solvent (DES) modified surface AC was used for Carbon Dioxide (CO2) capture in the fixed-bed column. The AC underwent pre-carbonization and carbonization processes at 519.8 °C, respectively, with flowing of CO2 gas and then followed by impregnation with 53.75% phosphoric acid (H3PO4) at 1:2 precursor-to-activant ratios. The prepared AC known as sea mango activated carbon (SMAC) was impregnated with DES at 1:2 solid-to-liquid ratio. The DES is composing of choline chloride and urea with ratio 1:2 choline chloride to urea. The optimum adsorption capacity of SMAC was 33.46 mgco2/gsol and 39.40 mgco2/gsol for DES modified AC (DESAC).

  5. Sorption studies of nickel ions onto activated carbon

    NASA Astrophysics Data System (ADS)

    Joshi, Parth; Vyas, Meet; Patel, Chirag

    2018-05-01

    Activated porous carbons are made through pyrolysis and activation of carbonaceous natural as well as synthetic precursors. The use of low-cost activated carbon derived from azadirachta indica, an agricultural waste material, has been investigated as a replacement for the current expensive methods of removing nickel ions from wastewater. The temperature variation study showed that the nickel ions adsorption is endothermic and spontaneous with increased randomness at the solid solution interface. Significant effect on adsorption was observed on varying the pH of the nickel ion solutions. Therefore, this study revealed that azadirachta indica can serve as a good source of activated carbon with multiple and simultaneous metal ions removing potentials and may serve as a better replacement for commercial activated carbons in applications that warrant their use.

  6. Naphthalene SOA: redox activity and naphthoquinone gas-particle partitioning

    NASA Astrophysics Data System (ADS)

    McWhinney, R. D.; Zhou, S.; Abbatt, J. P. D.

    2013-10-01

    Chamber secondary organic aerosol (SOA) from low-NOx photooxidation of naphthalene by hydroxyl radical was examined with respect to its redox cycling behaviour using the dithiothreitol (DTT) assay. Naphthalene SOA was highly redox-active, consuming DTT at an average rate of 118 ± 14 pmol per minute per μg of SOA material. Measured particle-phase masses of the major previously identified redox active products, 1,2- and 1,4-naphthoquinone, accounted for only 21 ± 3% of the observed redox cycling activity. The redox-active 5-hydroxy-1,4-naphthoquinone was identified as a new minor product of naphthalene oxidation, and including this species in redox activity predictions increased the predicted DTT reactivity to 30 ± 5% of observations. These results suggest that there are substantial unidentified redox-active SOA constituents beyond the small quinones that may be important toxic components of these particles. A gas-to-SOA particle partitioning coefficient was calculated to be (7.0 ± 2.5) × 10-4 m3 μg-1 for 1,4-naphthoquinone at 25 °C. This value suggests that under typical warm conditions, 1,4-naphthoquinone is unlikely to contribute strongly to redox behaviour of ambient particles, although further work is needed to determine the potential impact under conditions such as low temperatures where partitioning to the particle is more favourable. Also, higher order oxidation products that likely account for a substantial fraction of the redox cycling capability of the naphthalene SOA are likely to partition much more strongly to the particle phase.

  7. Synthesis and characterization of activated carbon from white lotus via single step chemical activation

    NASA Astrophysics Data System (ADS)

    Andas, Jeyashelly; Midon, Muhammad Dzulfiqar

    2017-08-01

    Highly porous activated carbon was successfully fabricated from the stalk of Nymphaea odorata via single step chemical activation. ZnCl2 was used as the chemical activating agent in the activation process. The raw material was preliminary characterized using Fourier Transform Infrared (FTIR), ultimate analysis (CHNS/O Analyzer) and Scanning Electron Microscope (SEM). The percentage yield, iodine number (IN) and the textural properties of the activated carbon were optimized under the influence of several synthesizing parameters such as impregnation ratio, activation temperature and activation time using ZnCl2. High IN (750.11 mg/g - 967.16 mg/g) was obtained from Sodium thiosulphate volumetric method and represents the porosity of the synthesized materials. Reduction in several functional groups was observed in the FTIR spectrum of the synthesized activated carbon. SEM analysis of the activated carbon verified the formation of highly porous surface compared to the raw Nymphaea odorata. This study provides a facile synthesis of activated carbon from waste natural resources at benign condition.

  8. (Bio)hybrid materials based on optically active particles

    NASA Astrophysics Data System (ADS)

    Reitzig, Manuela; Härtling, Thomas; Opitz, Jörg

    2014-03-01

    In this contribution we provide an overview of current investigations on optically active particles (nanodiamonds, upconversion phospors) for biohybrid and sensing applications. Due to their outstanding properties nanodiamonds gain attention in various application elds such as microelectronics, optical monitoring, medicine, and biotechnology. Beyond the typical diamond properties such as high thermal conductivity and extreme hardness, the carbon surface and its various functional groups enable diverse chemical and biological surface functionalization. At Fraunhofer IKTS-MD we develop a customization of material surfaces via integration of chemically modi ed nanodiamonds at variable surfaces, e.g bone implants and pipelines. For the rst purpose, nanodiamonds are covalently modi ed at their surface with amino or phosphate functionalities that are known to increase adhesion to bone or titanium alloys. The second type of surface is approached via mechanical implementation into coatings. Besides nanodiamonds, we also investigate the properties of upconversion phosphors. In our contribution we show how upconversion phosphors are used to verify sterilization processes via a change of optical properties due to sterilizing electron beam exposure.

  9. Grafting of activated carbon cloths for selective adsorption

    NASA Astrophysics Data System (ADS)

    Gineys, M.; Benoit, R.; Cohaut, N.; Béguin, F.; Delpeux-Ouldriane, S.

    2016-05-01

    Chemical functionalization of an activated carbon cloth with 3-aminophthalic acid and 4-aminobenzoic acid groups by the in situ formation of the corresponding diazonium salt in aqueous acidic solution is reported. The nature and amount of selected functions on an activated carbon surface, in particular the grafted density, were determined by potentiometric titration, elemental analysis and X-ray photoelectron spectroscopy (XPS). The nanotextural properties of the modified carbon were explored by gas adsorption. Functionalized activated carbon cloth was obtained at a discrete grafting level while preserving interesting textural properties and a large porous volume. Finally, the grafting homogeneity of the carbon surface and the nature of the chemical bonding were investigated using Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) technique.

  10. Depositing nanometer-sized particles of metals onto carbon allotropes

    NASA Technical Reports Server (NTRS)

    Delozier, Donavon M. (Inventor); Fallbach, Michael J. (Inventor); Smith, Joseph G. (Inventor); Watson, Kent A. (Inventor); Ghose, Sayata (Inventor); Connell, John W. (Inventor)

    2010-01-01

    A process for depositing nanometer-sized metal particles onto a substrate in the absence of aqueous solvents, organic solvents, and reducing agents, and without any required pre-treatment of the substrate, includes preparing an admixture of a metal compound and a substrate by dry mixing a chosen amount of the metal compound with a chosen amount of the substrate; and supplying energy to the admixture in an amount sufficient to deposit zero valance metal particles onto the substrate. This process gives rise to a number of deposited metallic particle sizes which may be controlled. The compositions prepared by this process are used to produce polymer composites by combining them with readily available commodity and engineering plastics. The polymer composites are used as coatings, or they are used to fabricate articles, such as free-standing films, fibers, fabrics, foams, molded and laminated articles, tubes, adhesives, and fiber reinforced articles. These articles are well-suited for many applications requiring thermal conductivity, electrical conductivity, antibacterial activity, catalytic activity, and combinations thereof.

  11. Preparation and Characterization of Impregnated Commercial Rice Husks Activated Carbon with Piperazine for Carbon Dioxide (CO2) Capture

    NASA Astrophysics Data System (ADS)

    Masoum Raman, S. N.; Ismail, N. A.; Jamari, S. S.

    2017-06-01

    Development of effective materials for carbon dioxide (CO2) capture technology is a fundamental importance to reduce CO2 emissions. This work establishes the addition of amine functional group on the surface of activated carbon to further improve the adsorption capacity of CO2. Rice husks activated carbon were modified using wet impregnation method by introducing piperazine onto the activated carbon surfaces at different concentrations and mixture ratios. These modified activated carbons were characterized by using X-Ray Diffraction (XRD), Brunauer, Emmett and Teller (BET), Fourier Transform Infrared Spectroscopy (FTIR) and Field Emission Scanning Electron Microscopy (FESEM). The results from XRD analysis show the presence of polyethylene butane at diffraction angles of 21.8° and 36.2° for modified activated carbon with increasing intensity corresponding to increase in piperazine concentration. BET results found the surface area and pore volume of non-impregnated activated carbon to be 126.69 m2/g and 0.081 cm3/g respectively, while the modified activated carbons with 4M of piperazine have lower surface area and pore volume which is 6.77 m2/g and 0.015 cm3/g respectively. At 10M concentration, the surface area and pore volume are the lowest which is 4.48 m2/g and 0.0065 cm3/g respectively. These results indicate the piperazine being filled inside the activated carbon pores thus, lowering the surface area and pore volume of the activated carbon. From the FTIR analysis, the presence of peaks at 3312 cm-1 and 1636 cm-1 proved the existence of reaction between carboxyl groups on the activated carbon surfaces with piperazine. The surface morphology of activated carbon can be clearly seen through FESEM analysis. The modified activated carbon contains fewer pores than non-modified activated carbon as the pores have been covered with piperazine.

  12. Influence of gas temperature on ignition, burning and extinction of carbon particles-gas suspension

    NASA Astrophysics Data System (ADS)

    Orlovskaya, S. G.; Zuy, O. N.; Liseanskaia, M. V.

    2017-11-01

    The ignition and burning of monodisperse and two-fraction suspensions of carbon particles at gas temperature in the range 1100 ÷ 1500 K are modeled. The critical gas temperature of the suspension ignition, the particles ignition delay and burning time, the burning temperature, and the extinction parameters are determined. The data obtained are compared with burning characteristics of single particle of equal size. The ignition temperatures of the fine fraction (the particle diameter 60 μm) and the coarse one (120 μm) are practically the same. The ignition temperatures of the equivalent single particles are much higher and they differ by 100 K and more. The gas temperature is found below which the ignition delay of the fine fraction exceeds the one of the coarse fraction. It is found that, at critical ignition temperatures the burning temperature of the fine fraction is lower than that of the coarse fraction. At gas temperatures above 1250 K, the burning temperature of the fine fraction is higher. It is established that, in contrast to single particles, the temperature difference between the particles and the gas is small during gas-suspension extinction. Further oxidation of the particles occurs in the kinetic regime, so it is possible to estimate the time of their complete conversion.

  13. Arctic Black Carbon Loading and Profile Using the Single-Particle Soot Photometer (SP2) Field Campaign Report

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sedlacek, Arthur J

    One of the major issues confronting aerosol climate simulations of the Arctic and Antarctic cryospheres is the lack of detailed data on the vertical and spatial distribution of aerosols with which to test these models. This is due, in part, to the inherent difficulty of conducting such measurements in extreme environments. However given the pronounced sensitivity of the polar regions to radiative balance perturbations, it is incumbent upon our community to better understand and quantify these perturbations, and their unique feedbacks, so that robust model predictions of this region can be realized. One class of under-measured radiative forcing agents inmore » the polar region is the absorbing aerosol—black carbon and brown carbon. Black carbon (BC; also referred to as light-absorbing carbon [LAC], refractory black carbon [rBC], and soot) is second only to CO2 as a positive forcing agent. Roughly 60% of BC emissions can be attributed to anthropogenic sources (fossil fuel combustion and open-pit cooking), with the remaining fraction being due to biomass burning. Brown carbon (BrC), a major component of biomass burning, collectively refers to non-BC carbonaceous aerosols that typically possess minimal light absorption at visible wavelengths but exhibit pronounced light absorption in the near-ultraviolet (UV) spectrum. Both species can be sourced locally or be remotely transported to the Arctic region and are expected to perturb the radiative balance. The work conducted in this field campaign addresses one of the more glaring deficiencies currently limiting improved quantification of the impact of BC radiative forcing in the cryosphere: the paucity of data on the vertical and spatial distributions of BC. By expanding the Gulfstream aircraft (G-1) payload for the U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Climate Research Facility-sponsored ACME-V campaign to include the Single-Particle Soot Photometer (SP2)) and leveraging the ACME

  14. Shape and Displacement Fluctuations in Soft Vesicles Filled by Active Particles

    PubMed Central

    Paoluzzi, Matteo; Di Leonardo, Roberto; Marchetti, M. Cristina; Angelani, Luca

    2016-01-01

    We investigate numerically the dynamics of shape and displacement fluctuations of two-dimensional flexible vesicles filled with active particles. At low concentration most of the active particles accumulate at the boundary of the vesicle where positive particle number fluctuations are amplified by trapping, leading to the formation of pinched spots of high density, curvature and pressure. At high concentration the active particles cover the vesicle boundary almost uniformly, resulting in fairly homogeneous pressure and curvature, and nearly circular vesicle shape. The change between polarized and spherical shapes is driven by the number of active particles. The center-of-mass of the vesicle performs a persistent random walk with a long time diffusivity that is strongly enhanced for elongated active particles due to orientational correlations in their direction of propulsive motion. In our model shape-shifting induces directional sensing and the cell spontaneously migrate along the polarization direction. PMID:27678166

  15. Exposure to ultrafine particles in asphalt work.

    PubMed

    Elihn, Karine; Ulvestad, Bente; Hetland, Siri; Wallen, Anna; Randem, Britt Grethe

    2008-12-01

    An epidemiologic study has demonstrated that asphalt workers show increased loss of lung function and an increase of biomarkers of inflammation over the asphalt paving season. The aim of this study was to investigate which possible agent(s) causes the inflammatory reaction, with emphasis on ultrafine particles. The workers' exposure to total dust, polycyclic aromatic hydrocarbons, and NO(2) was determined by personal sampling. Exposure to ultrafine particles was measured by means of particle counters and scanning mobility particle sizer mounted on a van following the paving machine. The fractions of organic and elemental carbon were determined. Asphalt paving workers were exposed to ultrafine particles with medium concentration of about 3.4 x 10(4)/cm(3). Ultrafine particles at the paving site originated mainly from asphalt paving activities and traffic exhaust; most seemed to originate from asphalt fumes. Oil mist exceeded occupational limits on some occasions. Diesel particulate matter was measured as elemental carbon, which was low, around 3 microg/m(3). NO(2) and total dust did not exceed limits. Asphalt pavers were exposed to relatively high concentrations of ultrafine particles throughout their working day, with possible adverse health effects.

  16. Biomass-based palm shell activated carbon and palm shell carbon molecular sieve as gas separation adsorbents.

    PubMed

    Sethupathi, Sumathi; Bashir, Mohammed Jk; Akbar, Zinatizadeh Ali; Mohamed, Abdul Rahman

    2015-04-01

    Lignocellulosic biomass has been widely recognised as a potential low-cost source for the production of high added value materials and proved to be a good precursor for the production of activated carbons. One of such valuable biomasses used for the production of activated carbons is palm shell. Palm shell (endocarp) is an abundant by-product produced from the palm oil industries throughout tropical countries. Palm shell activated carbon and palm shell carbon molecular sieve has been widely applied in various environmental pollution control technologies, mainly owing to its high adsorption performance, well-developed porosity and low cost, leading to potential applications in gas-phase separation using adsorption processes. This mini-review represents a comprehensive overview of the palm shell activated carbon and palm shell carbon molecular sieve preparation method, physicochemical properties and feasibility of palm shell activated carbon and palm shell carbon molecular sieve in gas separation processes. Some of the limitations are outlined and suggestions for future improvements are pointed out. © The Author(s) 2015.

  17. Preparation and characterization of activated carbon produced from pomegranate seeds by ZnCl 2 activation

    NASA Astrophysics Data System (ADS)

    Uçar, Suat; Erdem, Murat; Tay, Turgay; Karagöz, Selhan

    2009-08-01

    In this study, pomegranate seeds, a by-product of fruit juice industry, were used as precursor for the preparation of activated carbon by chemical activation with ZnCl 2. The influence of process variables such as the carbonization temperature and the impregnation ratio on textural and chemical-surface properties of the activated carbons was studied. When using the 2.0 impregnation ratio at the carbonization temperature of 600 °C, the specific surface area of the resultant carbon is as high as 978.8 m 2 g -1. The results showed that the surface area and total pore volume of the activated carbons at the lowest impregnation ratio and the carbonization temperature were achieved as high as 709.4 m 2 g -1 and 0.329 cm 3 g -1. The surface area was strongly influenced by the impregnation ratio of activation reagent and the subsequent carbonization temperature.

  18. Adsorption kinetics of surfactants on activated carbon

    NASA Astrophysics Data System (ADS)

    Arnelli; Aditama, WP; Fikriani, Z.; Astuti, Y.

    2018-04-01

    A study on the adsorption of both cationic and anionic surfactants using activated carbon as well as the investigation of the adsorption isotherms and adsorption kinetics has been conducted. The results showed that the adsorption of sodium lauryl sulfate (SLS) by activated carbon was Langmuir’s adsorption isotherm while its adsorption kinetics showed pseudo-second order with an adsorption rate constant of 2.23 x 103 g mg-1 hour-1. Meanwhile, the adsorption of HDTMA-Br by activated carbon showed that the isotherm adsorption tended to follow Freundlich’s isotherm and was pseudo-second order with an adsorption rate constant of 89.39 g mg-1 hour-1.

  19. Carbon Mineralization in Two Ultisols Amended with Different Sources and Particle Sizes of Pyrolyzed Biochar

    EPA Science Inventory

    Biochar produced during pyrolysis has the potential to enhance soil fertility and reduce greenhouse gas emissions. The influence of biochar properties (e.g., particle size) on both short- and long-term carbon (C) mineralization of biochar remains unclear. There is minimal informa...

  20. Activated carbons from KOH-activation of argan (Argania spinosa) seed shells as supercapacitor electrodes.

    PubMed

    Elmouwahidi, Abdelhakim; Zapata-Benabithe, Zulamita; Carrasco-Marín, Francisco; Moreno-Castilla, Carlos

    2012-05-01

    Activated carbons were prepared by KOH-activation of argan seed shells (ASS). The activated carbon with the largest surface area and most developed porosity was superficially treated to introduce oxygen and nitrogen functionalities. Activated carbons with a surface area of around 2100 m(2)/g were obtained. Electrochemical measurements were carried out with a three-electrode cell using 1M H(2)SO(4) as electrolyte and Ag/AgCl as reference electrode. The O-rich activated carbon showed the lowest capacitance (259 F/g at 125 mA/g) and the lowest capacity retention (52% at 1A/g), due to surface carboxyl groups hindering electrolyte diffusion into the pores. Conversely, the N-rich activated carbon showed the highest capacitance (355 F/g at 125 mA/g) with the highest retention (93% at 1A/g), due to its well-developed micro-mesoporosity and the pseudocapacitance effects of N functionalities. This capacitance performance was among the highest reported for other activated carbons from a large variety of biomass precursors. Copyright © 2012 Elsevier Ltd. All rights reserved.

  1. Decolorization of Cheddar cheese whey by activated carbon.

    PubMed

    Zhang, Yue; Campbell, Rachel; Drake, MaryAnne; Zhong, Qixin

    2015-05-01

    Colored Cheddar whey is a source for whey protein recovery and is decolorized conventionally by bleaching, which affects whey protein quality. Two activated carbons were studied in the present work as physical means of removing annatto (norbixin) in Cheddar cheese whey. The color and residual norbixin content of Cheddar whey were reduced by a higher level of activated carbon at a higher temperature between 25 and 55°C and a longer time. Activated carbon applied at 40g/L for 2h at 30°C was more effective than bleaching by 500mg/L of hydrogen peroxide at 68°C. The lowered temperature in activated-carbon treatments had less effect on protein structure as investigated for fluorescence spectroscopy and volatile compounds, particularly oxidation products, based on gas chromatography-mass spectrometry. Activated carbon was also reusable, removing more than 50% norbixin even after 10 times of regeneration, which showed great potential for decolorizing cheese whey. Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  2. Toward High-Performance and Low-Cost Hydrogen Evolution Reaction Electrocatalysts: Nanostructuring Cobalt Phosphide (CoP) Particles on Carbon Fiber Paper.

    PubMed

    Yu, Shu Hearn; Chua, Daniel H C

    2018-05-02

    In this communication, we facily fabricated nanostructured CoP particles (150 to 200 nm) on carbon fiber paper (CFP) for hydrogen evolution reaction (HER) by a simple two-step process via a green route. In the first step, crystalline Co 3 O 4 nanocubes (150-200 nm) were loaded on CFP through a hydrothermal process at low temperature (120 °C). Interestingly, crystalline Co 3 O 4 nanocubes with a size 150-200 nm exhibited different growth mechanisms in contrast to the crystalline Co 3 O 4 nanocubes with a size <100 nm reported earlier. In the second step, these crystalline Co 3 O 4 nanocubes were converted to catalytically active CoP particles through chemical vapor deposition (CVD) phosphorization (denoted as CoP/CFP-H). Remarkably, CoP/CFP-H exhibited a low Tafel slope of 49.7 mV/dec and only required overpotentials of 128.1, 144.4, and 190.8 mV to drive geometric current densities of -10, -20, and -100 mA cm -2 , respectively. Besides, the CoP/CFP-H also demonstrated an excellent durability in an acidic environment under 2000 sweeps at a high scan rate (100 mV s -1 ) and a 24 h chronopotentiometry testing. For comparison, CoP was also fabricated through the electrodeposition method, followed by CVD phosphorization (denoted as CoP/CFP-E). It was found that the latter had exhibited inferior activity compared to CoP/CFP-H. The good performances of CoP/CFP-H are essentially due to the rational designs of electrode: (i) the applications of highly HER active CoP electrocatalyst, (ii) the intimate contact of nanostructured CoP on carbon fibers, and (iii) the large electrochemical surface area at electrocatalyst/electrolyte interface due to the large retaining of particles features after phosphorization. Notably, the intermediate Co 3 O 4 /CFP can serve as a platform to develop other cobalt-based functional materials.

  3. Collective motion of active Brownian particles with polar alignment.

    PubMed

    Martín-Gómez, Aitor; Levis, Demian; Díaz-Guilera, Albert; Pagonabarraga, Ignacio

    2018-04-04

    We present a comprehensive computational study of the collective behavior emerging from the competition between self-propulsion, excluded volume interactions and velocity-alignment in a two-dimensional model of active particles. We consider an extension of the active brownian particles model where the self-propulsion direction of the particles aligns with the one of their neighbors. We analyze the onset of collective motion (flocking) in a low-density regime (10% surface area) and show that it is mainly controlled by the strength of velocity-alignment interactions: the competition between self-propulsion and crowding effects plays a minor role in the emergence of flocking. However, above the flocking threshold, the system presents a richer pattern formation scenario than analogous models without alignment interactions (active brownian particles) or excluded volume effects (Vicsek-like models). Depending on the parameter regime, the structure of the system is characterized by either a broad distribution of finite-sized polar clusters or the presence of an amorphous, highly fluctuating, large-scale traveling structure which can take a lane-like or band-like form (and usually a hybrid structure which is halfway in between both). We establish a phase diagram that summarizes collective behavior of polar active brownian particles and propose a generic mechanism to describe the complexity of the large-scale structures observed in systems of repulsive self-propelled particles.

  4. Anisotropy measurement of pyrolytic carbon layers of coated particles

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Vesyolkin, Ju. A., E-mail: Ju.Ves@yandex.ru; Ivanov, A. S., E-mail: asi.kiae@gmail.com; Trushkina, T. V.

    2015-12-15

    Equipment at the National Research Center Kurchatov Institute intended for the anisotropy determination of pyrolytic carbon layers in coated particles (CPs) of the GT-MGR reactor is tested and calibrated. The dependence of the anisotropy coefficient on the size of the measurement region is investigated. The results of measuring the optical anisotropy factor (OPTAF) for an aluminum mirror, rutile crystal, and available CP samples with the known characteristics measured previously using ORNL equipment (United States) are presented. In addition, measurements of CP samples prepared at VNIINM are performed. A strong dependence of the data on the preparation quality of metallographic sectionsmore » is found. Our investigations allow us to make the conclusion on the working capacity of the existing equipment for measuring the anisotropy of pyrolytic carbon CP coatings using the equipment at the Kurchatov Institute with the relative error of about 1%. It is shown that the elimination of the errors caused by the stochastic fluctuations in a measuring path by mathematical processing of the signal allows us to decrease the relative error of OPTAF measurements to ∼0.3%.« less

  5. How do changes in bulk soil organic carbon content affect carbon concentrations in individual soil particle fractions?

    PubMed Central

    Yang, X. M.; Drury, C. F.; Reynolds, W. D.; Yang, J. Y.

    2016-01-01

    We test the common assumption that organic carbon (OC) storage occurs on sand-sized soil particles only after the OC storage capacity on silt- and clay-sized particles is saturated. Soil samples from a Brookston clay loam in Southwestern Ontario were analysed for the OC concentrations in bulk soil, and on the clay (<2 μm), silt (2–53 μm) and sand (53–2000 μm) particle size fractions. The OC concentrations in bulk soil ranged from 4.7 to 70.8 g C kg−1 soil. The OC concentrations on all three particle size fractions were significantly related to the OC concentration of bulk soil. However, OC concentration increased slowly toward an apparent maximum on silt and clay, but this maximum was far greater than the maximum predicted by established C sequestration models. In addition, significant increases in OC associated with sand occurred when the bulk soil OC concentration exceeded 30 g C kg−1, but this increase occurred when the OC concentration on silt + clay was still far below the predicted storage capacity for silt and clay fractions. Since the OC concentrations in all fractions of Brookston clay loam soil continued to increase with increasing C (bulk soil OC content) input, we concluded that the concept of OC storage capacity requires further investigation. PMID:27251365

  6. How do changes in bulk soil organic carbon content affect carbon concentrations in individual soil particle fractions?

    NASA Astrophysics Data System (ADS)

    Yang, X. M.; Drury, C. F.; Reynolds, W. D.; Yang, J. Y.

    2016-06-01

    We test the common assumption that organic carbon (OC) storage occurs on sand-sized soil particles only after the OC storage capacity on silt- and clay-sized particles is saturated. Soil samples from a Brookston clay loam in Southwestern Ontario were analysed for the OC concentrations in bulk soil, and on the clay (<2 μm), silt (2-53 μm) and sand (53-2000 μm) particle size fractions. The OC concentrations in bulk soil ranged from 4.7 to 70.8 g C kg-1 soil. The OC concentrations on all three particle size fractions were significantly related to the OC concentration of bulk soil. However, OC concentration increased slowly toward an apparent maximum on silt and clay, but this maximum was far greater than the maximum predicted by established C sequestration models. In addition, significant increases in OC associated with sand occurred when the bulk soil OC concentration exceeded 30 g C kg-1, but this increase occurred when the OC concentration on silt + clay was still far below the predicted storage capacity for silt and clay fractions. Since the OC concentrations in all fractions of Brookston clay loam soil continued to increase with increasing C (bulk soil OC content) input, we concluded that the concept of OC storage capacity requires further investigation.

  7. Springtime carbon episodes at Gosan background site revealed by total carbon, stable carbon isotopic composition, and thermal characteristics of carbonaceous particles

    NASA Astrophysics Data System (ADS)

    Jung, J.; Kawamura, K.

    2011-05-01

    In order to investigate the carbon episodes at Gosan background super-site (33.17° N, 126.10° E) in East Asia during spring of 2007 and 2008, total suspended particles (TSP) were collected and analyzed for particulate organic carbon, elemental carbon, total carbon (TC), total nitrogen (TN), and stable carbon isotopic composition (δ13C) of TC. The carbon episodes at the Gosan site were categorized as long-range transported anthropogenic pollutant (LTP) from Asian continent, Asian dust (AD) accompanying with LTP, and local pollen episodes. The stable carbon isotopic composition of TC (δ13CTC) was found to be lowest during the pollen episodes (range: -26.2 ‰ to -23.5 ‰, avg.: -25.2 ± 0.9 ‰), followed by the LTP episodes (range: -23.5 ‰ to -23.0 ‰, avg.: -23.3 ± 0.3 ‰) and the AD episodes (range: -23.3 to -20.4 %, avg.: -21.8 ± 2.0 ‰). The δ13CTC of the airborne pollens (-28.0 ‰) collected at the Gosan site showed value similar to that of tangerine fruit (-28.1 ‰) produced from Jeju Island. Based on the carbon isotope mass balance equation and the TN and TC regression approach, we found that ∼40-45 % of TC in the TSP samples during the pollen episodes was attributed to airborne pollens from Japanese cedar trees planted around tangerine farms in Jeju Island. The δ13C of citric acid in the airborne pollens (-26.3 ‰) collected at the Gosan site was similar to that in tangerine fruit (-27.4 ‰). The negative correlation between the citric acid-carbon/TC ratios and δ13CTC were obtained during the pollen episodes. These results suggest that citric acid emitted from tangerine fruit may be adsorbed on the airborne pollens and then transported to the Gosan site. Based on the thermal evolution pattern of organic aerosols during the carbon episodes, we found that organic aerosols originated from East China are more volatile on heating and are more likely to form pyrolized organic carbon than the pollen-enriched organic aerosols and organic

  8. Thermal Oxidation of a Carbon Condensate Formed in High-Frequency Carbon and Carbon-Nickel Plasma Flow

    NASA Astrophysics Data System (ADS)

    Churilov, G. N.; Nikolaev, N. S.; Cherepakhin, A. V.; Dudnik, A. I.; Tomashevich, E. V.; Trenikhin, M. V.; Bulina, N. G.

    2018-02-01

    We have reported on the comparative characteristics of thermal oxidation of a carbon condensate prepared by high-frequency arc evaporation of graphite rods and a rod with a hollow center filled with nickel powder. In the latter case, along with different forms of nanodisperse carbon, nickel particles with nickel core-carbon shell structures are formed. It has been found that the processes of the thermal oxidation of carbon condensates with and without nickel differ significantly. Nickel particles with the carbon shell exhibit catalytic properties with respect to the oxidation of nanosized carbon structures. A noticeable difference between the temperatures of the end of the oxidation process for various carbon nanoparticles and nickel particles with the carbon shell has been established. The study is aimed at investigations of the effect of nickel nanoparticles on the dynamics of carbon condensate oxidation upon heating in the argon-oxygen flow.

  9. Synthesis of copper particles covered with cobalt-catalyzed carbon nanofibers and their application to air-curable conductive paste

    NASA Astrophysics Data System (ADS)

    Ohnishi, Shigekatsu; Nakasuga, Akira; Nakagawa, Kiyoharu

    2017-07-01

    Sea urchin-shaped hybrid copper powder (HCuP), which is characterized by copper alloy powder particles covered with vertically aligned Co-catalyzed carbon nanofibers (CNFs), was successfully synthesized to improve the oxidation resistance of copper paste. Fine spherical CuCo alloy particles with nominal composition of Cu/Co = 99/1 w/w were fabricated by atomization. Cobalt nanoprecipitates (CoNPs) used as the catalyst for carbon fiber growth were arranged on the surface of an alloy particle by heat treatment. CNFs were grown from the CoNPs on the alloy particle via thermal chemical vapor deposition (CVD). The conductive paste was prepared by milling using HCuP with resin and oleic acid. HCuP paste was screen-printed on a glass or plastic substrate and showed a resistivity as low as 1.2 × 10-4 Ω·cm after curing at 150 °C for 30 min in air (21% oxygen). These results indicate that the use of HCuP is a promising technology for printable electronics in a sustainable society.

  10. Effect of storage temperature on the activity of submitochondrial particles.

    PubMed

    Doherty, Francis G

    2008-12-01

    The submitochondrial particle (SMP) assay employs processed mammalian mitchondria to assess the toxicity of chemical contaminants in aqueous solutions. Particles and associated reagents are commercially available to support two individual procedures, the electron transfer (ETr) and reverse electron transfer (RET) assays. The objective of the present study was to assess the effect of storage temperature on SMP activity. One RET and one ETr assay were conducted with sodium dodecylsulfate on each of two vials of particles stored at -20 and -80 degrees C at periodic intervals over a six-month span. Results demonstrated that SMP could remain active in either assay through six months of storage at either temperature. However, there were isolated vials of particles stored at -20 degrees C that exhibited unacceptable reductions in activity for both the ETr and the RET assays that were not related to storage duration. These results were used to develop guidance in assessing the acceptability of particle activity in SMP assays.

  11. Unhealthy diet and ultrafine carbon black particles induce senescence and disease associated phenotypic changes.

    PubMed

    Büchner, Nicole; Ale-Agha, Niloofar; Jakob, Sascha; Sydlik, Ulrich; Kunze, Kerstin; Unfried, Klaus; Altschmied, Joachim; Haendeler, Judith

    2013-01-01

    Diet and pollution are environmental factors known to compromise "healthy aging" of the cardiovascular and respiratory systems. The molecular consequences of this permanent burden in these cells are still unknown. Therefore, this study investigates the impact of unhealthy diet on aging-related signaling pathways of human, primary cardiovascular cells and of airborne particles on lung epithelial and human endothelial cells. Nutrition health reports have shown that the diet in industrialized countries contains more than 100mg/dl low density lipoprotein (LDL) and a high fraction of added sugars, especially fructose. Several studies demonstrated that ultrafine particles can enter the circulation and thus may interact with endothelial cells directly. Both, dietary compounds and pollution derived particles, have been shown to increase the risk for cardiovascular diseases. To simulate an unhealthy diet, we supplemented cell culture media of human primary endothelial cells, smooth muscle cells and cardiomyocytes with LDL and replaced 1/3 of glucose with fructose. We observed hypertrophy in cardiomyocytes, enhanced proliferation in smooth muscle cells and increased senescence, loss of endothelial nitric oxide synthase and increased nuclear FoxO3A in endothelial cells. With respect to pollution we have used ultrafine carbon black particles (ufCB), one of the major constituents of industrial and exhaust emissions, in concentrations our lungs and vessels are constantly exposed to. These concentrations of ufCB increased reactive oxygen species in lung epithelial and vascular endothelial cells and reduced the S-NO content, a marker for NO-bioavailability, in endothelial cells. NO increases activation of Telomerase Reverse Transcriptase (TERT), an enzyme essential for telomere maintenance. TERT is required for proper endothelial cell function and is inactivated by Src kinase under conditions of oxidative stress. ufCB significantly increased Src kinase activation and reduced

  12. Microbial growth associated with granular activated carbon in a pilot water treatment facility.

    PubMed Central

    Wilcox, D P; Chang, E; Dickson, K L; Johansson, K R

    1983-01-01

    The microbial dynamics associated with granular activated carbon (GAC) in a pilot water treatment plant were investigated over a period of 16 months. Microbial populations were monitored in the influent and effluent waters and on the GAC particles by means of total plate counts and ATP assays. Microbial populations between the influent and effluent waters of the GAC columns generally increased, indicating microbial growth. The dominant genera of microorganisms isolated from interstitial waters and GAC particles were Achromobacter, Acinetobacter, Aeromonas, Alcaligenes, Bacillus, Chromobacterium, Corynebacterium, Micrococcus, Microcyclus, Paracoccus, and Pseudomonas. Coliform bacteria were found in small numbers in the effluents from some of the GAC columns in the later months of the study. Oxidation of influent waters with ozone and maintenance of aerobic conditions on the GAC columns failed to appreciably enhance the microbial growth on GAC. PMID:6625567

  13. Surface Modified Particles By Multi-Step Michael-Type Addition And Process For The Preparation Thereof

    DOEpatents

    Cook, Ronald Lee; Elliott, Brian John; Luebben, Silvia DeVito; Myers, Andrew William; Smith, Bryan Matthew

    2005-05-03

    A new class of surface modified particles and a multi-step Michael-type addition surface modification process for the preparation of the same is provided. The multi-step Michael-type addition surface modification process involves two or more reactions to compatibilize particles with various host systems and/or to provide the particles with particular chemical reactivities. The initial step comprises the attachment of a small organic compound to the surface of the inorganic particle. The subsequent steps attach additional compounds to the previously attached organic compounds through reactive organic linking groups. Specifically, these reactive groups are activated carbon—carbon pi bonds and carbon and non-carbon nucleophiles that react via Michael or Michael-type additions.

  14. Interactions Between Biogenic Silica (BSiO2) and Organic Carbon (POC) During the Recycling of Sinking Particles

    NASA Astrophysics Data System (ADS)

    Moriceau, B.; Goutx, M.; Guigue, C.; Tamburini, C.; Lee, C.; Armstrong, R. A.; Duflos, M.; Charriere, B.; Ragueneau, O.

    2006-12-01

    Despite recent progress in understanding the ocean's role in the global carbon cycle, we are not yet able to predict the response of ecosystems to climate change and feedbacks of the ocean onto atmospheric CO2. In particular, particle flux dynamics must be represented more faithfully in ocean models. We know that particulate organic carbon (POC) flux is associated with ballast minerals (BSiO2, CaCO3), but the processes controlling the interactions between carbon and ballast minerals during decomposition must be explored further. The present study aims to provide a better understanding of interactions between carbon and BSiO2 during mineralization of sinking particles. Previous studies have provided evidence that the degradation of the external membrane by bacteria increase the BSiO2 dissolution rate. Alternatively, it has been hypothesized that biogenic silica could protect carbon from degradation. To test this hypothesis, an in-vitro batch experiment using the diatom Skeletonema costatum was conducted. In this experiment, carbon degradation, bacterial growth, and BSiO2 dissolution were followed simultaneously. To identify the processes involved and the types of carbon that eventually interact with BSiO2 during mineralization, the concentrations of different lipids and amino acids were also measured. A strong increase of the degradation rate constant of the POC and PON was observed after dissolution of 40 % of initial BSiO2. This increase is associated to a peak of glycine in total amino acids and a switch between free and attached bacteria. These results suggest that carbon degradation is increased when enough of the frustule is dissolved to uncover the glycine contain inside the frustule, this amino acid may trigger an increase in the concentration of attached bacteria, which may in turn increase the degradation rate constant of organic carbon.

  15. The Carbon Aerosol / Particles Nucleation with a Lidar: Numerical Simulations and Field Studies

    NASA Astrophysics Data System (ADS)

    Miffre, Alain; Anselmo, Christophe; Francis, Mirvatte; David, Gregory; Rairoux, Patrick

    2016-06-01

    In this contribution, we present the results of two recent papers [1,2] published in Optics Express, dedicated to the development of two new lidar methodologies. In [1], while the carbon aerosol (for example, soot particles) is recognized as a major uncertainty on climate and public health, we couple lidar remote sensing with Laser-Induced-Incandescence (LII) to allow retrieving the vertical profile of very low thermal radiation emitted by the carbon aerosol, in agreement with Planck's law, in an urban atmosphere over several hundred meters altitude. In paper [2], awarded as June 2014 OSA Spotlight, we identify the optical requirements ensuring an elastic lidar to be sensitive to new particles formation events (NPF-events) in the atmosphere, while, in the literature, all the ingredients initiating nucleation are still being unrevealed [3]. Both papers proceed with the same methodology by identifying the optical requirements from numerical simulation (Planck and Kirchhoff's laws in [1], Mie and T-matrix numerical codes in [2]), then presenting lidar field application case studies. We believe these new lidar methodologies may be useful for climate, geophysical, as well as fundamental purposes.

  16. Chemical aging of single and multicomponent biomass burning aerosol surrogate-particles by OH: Implications for cloud condensation nucleus activity

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Thalman, R.; Thalman, R.; Wang, J.

    Multiphase OH and O₃ oxidation reactions with atmospheric organic aerosol (OA) can influence particle physicochemical properties including composition, morphology, and lifetime. Chemical aging of initially insoluble or low soluble single-component OA by OH and O₃ can increase their water-solubility and hygroscopicity, making them more active as cloud condensation nuclei (CCN) and susceptible to wet deposition. However, an outstanding problem is whether the effects of chemical aging on their CCN activity are preserved when mixed with other organic or inorganic compounds exhibiting greater water-solubility. In this work, the CCN activity of laboratory-generated biomass burning aerosol (BBA) surrogate-particles exposed to OH andmore » O₃ is evaluated by determining the hygroscopicity parameter, κ, as a function of particle type, mixing state, and OH/O₃ exposure applying a CCN counter (CCNc) coupled to an aerosol flow reactor (AFR). Levoglucosan (LEV), 4-methyl-5-nitrocatechol (MNC), and potassium sulfate (KS) serve as representative BBA compounds that exhibit different hygroscopicity, water solubility, chemical functionalities, and reactivity with OH radicals, and thus exemplify the complexity of mixed inorganic/organic aerosol in the atmosphere. The CCN activities of all of the particles were unaffected by O₃ exposure. Following exposure to OH, κ of MNC was enhanced by an order of magnitude, from 0.009 to ~0.1, indicating that chemically-aged MNC particles are better CCN and more prone to wet deposition than pure MNC particles. No significant enhancement in κ was observed for pure LEV particles following OH exposure. κ of the internally-mixed particles was not affected by OH oxidation. Furthermore, the CCN activity of OH exposed MNC-coated KS particles is similar to the OH unexposed atomized 1:1 by mass MNC: KS binary-component particles. Our results strongly suggest that when OA is dominated by water-soluble organic carbon (WSOC) or inorganic ions

  17. Chemical aging of single and multicomponent biomass burning aerosol surrogate-particles by OH: Implications for cloud condensation nucleus activity

    DOE PAGES

    Thalman, R.; Thalman, R.; Wang, J.; ...

    2015-03-06

    Multiphase OH and O₃ oxidation reactions with atmospheric organic aerosol (OA) can influence particle physicochemical properties including composition, morphology, and lifetime. Chemical aging of initially insoluble or low soluble single-component OA by OH and O₃ can increase their water-solubility and hygroscopicity, making them more active as cloud condensation nuclei (CCN) and susceptible to wet deposition. However, an outstanding problem is whether the effects of chemical aging on their CCN activity are preserved when mixed with other organic or inorganic compounds exhibiting greater water-solubility. In this work, the CCN activity of laboratory-generated biomass burning aerosol (BBA) surrogate-particles exposed to OH andmore » O₃ is evaluated by determining the hygroscopicity parameter, κ, as a function of particle type, mixing state, and OH/O₃ exposure applying a CCN counter (CCNc) coupled to an aerosol flow reactor (AFR). Levoglucosan (LEV), 4-methyl-5-nitrocatechol (MNC), and potassium sulfate (KS) serve as representative BBA compounds that exhibit different hygroscopicity, water solubility, chemical functionalities, and reactivity with OH radicals, and thus exemplify the complexity of mixed inorganic/organic aerosol in the atmosphere. The CCN activities of all of the particles were unaffected by O₃ exposure. Following exposure to OH, κ of MNC was enhanced by an order of magnitude, from 0.009 to ~0.1, indicating that chemically-aged MNC particles are better CCN and more prone to wet deposition than pure MNC particles. No significant enhancement in κ was observed for pure LEV particles following OH exposure. κ of the internally-mixed particles was not affected by OH oxidation. Furthermore, the CCN activity of OH exposed MNC-coated KS particles is similar to the OH unexposed atomized 1:1 by mass MNC: KS binary-component particles. Our results strongly suggest that when OA is dominated by water-soluble organic carbon (WSOC) or inorganic ions

  18. Brush in the bath of active particles: Anomalous stretching of chains and distribution of particles

    NASA Astrophysics Data System (ADS)

    Li, Hui-shu; Zhang, Bo-kai; Li, Jian; Tian, Wen-de; Chen, Kang

    2015-12-01

    The interaction between polymer brush and colloidal particles has been intensively studied in the last two decades. Here, we consider a flat chain-grafted substrate immersed in a bath of active particles. Simulations show that an increase in the self-propelling force causes an increase in the number of particles that penetrate into the brush. Anomalously, the particle density inside the main body of the brush eventually becomes higher than that outside the brush at very large self-propelling force. The grafted chains are further stretched due to the steric repulsion from the intruded particles. Upon the increase of the self-propelling force, distinct stretching behaviors of the chains were observed for low and high grafting densities. Surprisingly, we find a weak descent of the average end-to-end distance of chains at high grafting density and very large force which is reminiscent of the compression effect of a chain in the active bath.

  19. Carbon nanotubes grown on bulk materials and methods for fabrication

    DOEpatents

    Menchhofer, Paul A [Clinton, TN; Montgomery, Frederick C [Oak Ridge, TN; Baker, Frederick S [Oak Ridge, TN

    2011-11-08

    Disclosed are structures formed as bulk support media having carbon nanotubes formed therewith. The bulk support media may comprise fibers or particles and the fibers or particles may be formed from such materials as quartz, carbon, or activated carbon. Metal catalyst species are formed adjacent the surfaces of the bulk support material, and carbon nanotubes are grown adjacent the surfaces of the metal catalyst species. Methods employ metal salt solutions that may comprise iron salts such as iron chloride, aluminum salts such as aluminum chloride, or nickel salts such as nickel chloride. Carbon nanotubes may be separated from the carbon-based bulk support media and the metal catalyst species by using concentrated acids to oxidize the carbon-based bulk support media and the metal catalyst species.

  20. Particle and carbon dioxide emissions from passenger vehicles operating on unleaded petrol and LPG fuel.

    PubMed

    Ristovski, Z D; Jayaratne, E R; Morawska, L; Ayoko, G A; Lim, M

    2005-06-01

    A comprehensive study of the particle and carbon dioxide emissions from a fleet of six dedicated liquefied petroleum gas (LPG) powered and five unleaded petrol (ULP) powered new Ford Falcon Forte passenger vehicles was carried out on a chassis dynamometer at four different vehicle speeds--0 (idle), 40, 60, 80 and 100 km h(-1). Emission factors and their relative values between the two fuel types together with a statistical significance for any difference were estimated for each parameter. In general, LPG was found to be a 'cleaner' fuel, although in most cases, the differences were not statistically significant owing to the large variations between emissions from different vehicles. The particle number emission factors ranged from 10(11) to 10(13) km(-1) and was over 70% less with LPG compared to ULP. Corresponding differences in particle mass emission factor between the two fuels were small and ranged from the order of 10 microg km(-1) at 40 to about 1000 microg km(-1) at 100 km h(-1). The count median particle diameter (CMD) ranged from 20 to 35 nm and was larger with LPG than with ULP in all modes except the idle mode. Carbon dioxide emission factors ranged from about 300 to 400 g km(-1) at 40 km h(-1), falling with increasing speed to about 200 g km(-1) at 100 km h(-1). At all speeds, the values were 10% to 18% greater with ULP than with LPG.

  1. A facile production of microporous carbon spheres and their electrochemical performance in EDLC

    NASA Astrophysics Data System (ADS)

    Xia, Xiaohong; Shi, Lei; Liu, Hongbo; Yang, Li; He, Yuede

    2012-03-01

    In the absence of activation process, we prepared a series of carbon particles from saccharine, in which hydrothermal carbonization method was used. These particles have spherical or near-spherical morphology, controllable monodisperse particle size from the analyses of SEM. Raman and XRD results show that they are nongraphitizable. The BET surface area of these carbon spherules is around 400-500 m2 g-1 and the microporosity is about 84%, suggesting that the carbon particles are rich in micropores. The electrochemical behaviors were characterized by means of galvanostatic charging/discharging, cycle voltammetry and impedance spectroscopy. The results show that the specific capacitance of sucrose-based carbon spherule reached 164 F g-1 in 30% KOH electrolyte and a high volumetric capacitance over 170 F cm-3 was obtained. These carbon spherules could be promising materials for EDLC according to their facile preparation way, low cost and high packing density.

  2. Size controlled hydroxyapatite and calcium carbonate particles: synthesis and their application as templates for SERS platform.

    PubMed

    Parakhonskiy, B V; Svenskaya, Yu I; Yashchenok, A М; Fattah, H A; Inozemtseva, O A; Tessarolo, F; Antolini, R; Gorin, D A

    2014-06-01

    An elegant route for hydroxyapatite (HA) particle synthesis via ionic exchange reaction is reported. Calcium carbonate particles (CaCO3) were recrystallized into HA beads in water solution with phosphate ions. The size of initial CaCO3 particles was controlled upon the synthesis by varying the amount of ethylene glycol (EG) in aqueous solution. The average size of HA beads ranged from 0.6±0.1 to 4.3±1.1μm. Silver nanoparticles were deposited on the surface of HA and CaCO3 particles via silver mirror reaction. Surface enhanced Raman scattering of silver functionalized beads was demonstrated by detecting Rhodamine B. CaCO3 and HA particles have a great potential for design of carrier which can provide diagnostic and therapeutic functions. Copyright © 2014 Elsevier B.V. All rights reserved.

  3. Chemical activation of gasification carbon residue for phosphate removal

    NASA Astrophysics Data System (ADS)

    Kilpimaa, Sari; Runtti, Hanna; Lassi, Ulla; Kuokkanen, Toivo

    2012-05-01

    Recycling of waste materials provides an economical and environmentally significant method to reduce the amount of waste. Bioash formed in the gasification process possesses a notable amount of unburned carbon and therefore it can be called a carbon residue. After chemical activation carbon residue could be use to replace activated carbon for example in wastewater purification processes. The effect of chemical activation process variables such as chemical agents and contact time in the chemical activation process were investigated. This study also explored the effectiveness of the chemically activated carbon residue for the removal of phosphate from an aqueous solution. The experimental adsorption study was performed in a batch reactor and the influence of adsorption time, initial phosphate concentration and pH was studied. Due to the carbon residue's low cost and high adsorption capacity, this type of waste has the potential to be utilised for the cost-effective removal of phosphate from wastewaters. Potential adsorbents could be prepared from these carbonaceous by-products and used as an adsorbent for phosphate removal.

  4. Treated carbon fibers with improved performance for electrochemical and chemical applications

    DOEpatents

    Chu, X.; Kinoshita, Kimio

    1999-02-23

    A treated mesophase carbon fiber is disclosed having a high density of exposed edges on the fiber surface, and a method is described for making such a treated fiber. A carbon electrode is also described which is constructed from such treated mesophase carbon fibers. The resulting electrode, formed from such treated flexible carbon fibers, is characterized by a high density of active sites formed from such exposed edges, low corrosion, and good mechanical strength, and may be fabricated into various shapes. The treated mesophase carbon fibers of the invention are formed by first loading the surface of the mesophase carbon fiber with catalytic metal particles to form catalytic etch sites on a hard carbon shell of the fiber. The carbon fiber is then subject to an etch step wherein portions of the hard carbon shell or skin are selectively removed adjacent the catalytic metal particles adhering to the carbon shell. This exposes the underlying radial edges of the graphite-like layers within the carbon shell of the mesophase carbon fiber, which exposed radial edges then act as active sites of a carbon electrode subsequently formed from the treated mesophase carbon fibers. 14 figs.

  5. Treated carbon fibers with improved performance for electrochemical and chemical applications

    DOEpatents

    Chu, Xi; Kinoshita, Kimio

    1999-01-01

    A treated mesophase carbon fiber is disclosed having a high density of exposed edges on the fiber surface, and a method of making such a treated fiber. A carbon electrode is also described which is constructed from such treated mesophase carbon fibers. The resulting electrode, formed from such treated flexible carbon fibers, is characterized by a high density of active sites formed from such exposed edges, low corrosion, and good mechanical strength, and may be fabricated into various shapes. The treated mesophase carbon fibers of the invention are formed by first loading the surface of the mesophase carbon fiber with catalytic metal particles to form catalytic etch sites on a hard carbon shell of the fiber. The carbon fiber is then subject to an etch step wherein portions of the hard carbon shell or skin are selectively removed adjacent the catalytic metal particles adhering to the carbon shell. This exposes the underlying radial edges of the graphite-like layers within the carbon shell of the mesophase carbon fiber, which exposed radial edges then act as active sites of a carbon electrode subsequently formed from the treated mesophase carbon fibers.

  6. Adsorption of gold ions from industrial wastewater using activated carbon derived from hard shell of apricot stones - an agricultural waste.

    PubMed

    Soleimani, Mansooreh; Kaghazchi, Tahereh

    2008-09-01

    In this study, hard shell of apricot stones was selected from agricultural solid wastes to prepare effective and low cost adsorbent for the gold separation from gold-plating wastewater. Different adsorption parameters like adsorbent dose, particle size of activated carbon, pH and agitation speed of mixing on the gold adsorption were studied. The results showed that under the optimum operating conditions, more than 98% of gold was adsorbed onto activated carbon after only 3h. The equilibrium adsorption data were well described by the Freundlich and Langmuir isotherms. Isotherms have been used to obtain thermodynamic parameters. Gold desorption studies were performed with aqueous solution mixture of sodium hydroxide and organic solvents at ambient temperatures. Quantitative recovery of gold ions is possible by this method. As hard shell of apricot stones is a discarded as waste from agricultural and food industries, the prepared activated carbon is expected to be an economical product for gold ion recovery from wastewater.

  7. Gas-saturated solution process to obtain microcomposite particles of alpha lipoic acid/hydrogenated colza oil in supercritical carbon dioxide.

    PubMed

    Mishima, Kenji; Honjo, Masatoshi; Sharmin, Tanjina; Ito, Shota; Kawakami, Ryo; Kato, Takafumi; Misumi, Makoto; Suetsugu, Tadashi; Orii, Hideaki; Kawano, Hiroyuki; Irie, Keiichi; Sano, Kazunori; Mishima, Kenichi; Harada, Takunori; Ouchi, Mikio

    2016-09-01

    Alpha lipoic acid (ALA), an active substance in anti-aging products and dietary supplements, need to be masked with an edible polymer to obscure its unpleasant taste. However, the high viscosity of the ALA molecules prevents them from forming microcomposites with masking materials even in supercritical carbon dioxide (scCO2). Therefore, the purpose of this study was to investigate and develop a novel production method for microcomposite particles for ALA in hydrogenated colza oil (HCO). Microcomposite particles of ALA/HCO were prepared by using a novel gas-saturated solution (PGSS) process in which the solid-dispersion method is used along with stepwise temperature control (PGSS-STC). Its high viscosity prevents the formation of microcomposites in the conventional PGSS process even under strong agitation. Here, we disperse the solid particles of ALA and HCO in scCO2 at low temperatures and change the temperature stepwise in order to mix the melted ALA and HCO in scCO2. As a result, a homogeneous dispersion of the droplets of ALA in melted HCO saturated with CO2 is obtained at high temperatures. After the rapid expansion of the saturated solution through a nozzle, microcomposite particles of ALA/HCO several micrometers in diameter are obtained.

  8. Supercritical Carbon Dioxide Regeneration of Activated Carbon Loaded with Contaminants from Rocky Mountain Arsenal Well Water.

    DTIC Science & Technology

    1982-05-01

    PROCESSING COST OF ACTIVATED CHARCOAL REGENERATION BY SUPERCRITICAL CARBON DIOXIDE PROCESS ........................... 25 l IV-4 SENSITIVITY OF GAC...PROCESSING COSTS TO GAC WORKING CAPACITY ................................. 27 IV-5 ESTIMATED PROCESSING COST OF ACTIVATED CHARCOAL REGENERATION BY THERMAL...34 VI-2 COMPARISON OF THREE GRANULAR ACTIVATED CARBONS - SUPERCRITICAL CO2 REACTIVATION - GRANULAR CARBON ISOTHERMS - PHASE I RAW DATA

  9. Diffusion of active chiral particles

    NASA Astrophysics Data System (ADS)

    Sevilla, Francisco J.

    2016-12-01

    The diffusion of chiral active Brownian particles in three-dimensional space is studied analytically, by consideration of the corresponding Fokker-Planck equation for the probability density of finding a particle at position x and moving along the direction v ̂ at time t , and numerically, by the use of Langevin dynamics simulations. The analysis is focused on the marginal probability density of finding a particle at a given location and at a given time (independently of its direction of motion), which is found from an infinite hierarchy of differential-recurrence relations for the coefficients that appear in the multipole expansion of the probability distribution, which contains the whole kinematic information. This approach allows the explicit calculation of the time dependence of the mean-squared displacement and the time dependence of the kurtosis of the marginal probability distribution, quantities from which the effective diffusion coefficient and the "shape" of the positions distribution are examined. Oscillations between two characteristic values were found in the time evolution of the kurtosis, namely, between the value that corresponds to a Gaussian and the one that corresponds to a distribution of spherical shell shape. In the case of an ensemble of particles, each one rotating around a uniformly distributed random axis, evidence is found of the so-called effect "anomalous, yet Brownian, diffusion," for which particles follow a non-Gaussian distribution for the positions yet the mean-squared displacement is a linear function of time.

  10. Preparation of Activated Carbon from Palm Shells Using KOH and ZnCl2 as the Activating Agent

    NASA Astrophysics Data System (ADS)

    Yuliusman; Nasruddin; Afdhol, M. K.; Amiliana, R. A.; Hanafi, A.

    2017-07-01

    Palm shell is a potential source of raw materials for the produce of activated carbon as biosorbent for quite large numbers. The purpose of this study is to produce activated carbon qualified Indonesian Industrial Standard (SNI), which will be used as biosorbent to purify the impurities in the off gas petroleum refinery products. Stages of manufacture of activated carbon include carbonization, activation of chemistry and physics. Carbonization of activated carbon is done at a temperature of 400°C followed by chemical activation with active agent KOH and ZnCl2. Then the physical activation is done by flowing N2 gas for 1 hour at 850°C and followed by gas flow through the CO2 for 1 hour at 850°C. Research results indicate that activation of the active agent KOH produce activated carbon is better than using the active agent ZnCl2. The use of KOH as an active agent to produce activated carbon with a water content of 13.6%, ash content of 9.4%, iodine number of 884 mg/g and a surface area of 1115 m2/g. While the use of ZnCl2 as the active agent to produce activated carbon with a water content of 14.5%, total ash content of 9.0%, iodine number 648 mg/g and a surface area of 743 m2/g.

  11. Diclofenac removal from water with ozone and activated carbon.

    PubMed

    Beltrán, Fernando J; Pocostales, Pablo; Alvarez, Pedro; Oropesa, Ana

    2009-04-30

    Diclofenac (DCF) has been treated in water with ozone in the presence of various activated carbons. Activated carbon-free ozonation or single ozonation leads to a complete degradation of DCF in less than 15 min while in the presence of activated carbons higher degradation rates of TOC and DCF are noticeably achieved. Among the activated carbons used, P110 Hydraffin was found the most suitable for the catalytic ozonation of DCF. The influence of pH was also investigated. In the case of the single ozonation the increasing pH slightly increases the TOC removal rate. This effect, however, was not so clear in the presence of activated carbons where the influence of the adsorption process must be considered. Ecotoxicity experiments were performed, pointing out that single ozonation reduces the toxicity of the contaminated water but catalytic ozonation improved those results. As far as kinetics is concerned, DCF is removed with ozone in a fast kinetic regime and activated carbon merely acts as a simple adsorbent. However, for TOC removal the ozonation kinetic regime becomes slow. In the absence of the adsorbent, the apparent rate constant of the mineralization process was determined at different pH values. On the other hand, determination of the rate constant of the catalytic reaction over the activated carbon was not possible due to the effect of mass transfer resistances that controlled the process rate at the conditions investigated.

  12. Chemical aging of single and multicomponent biomass burning aerosol surrogate particles by OH: implications for cloud condensation nucleus activity

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Slade, J. H.; Thalman, R.; Wang, J.

    Multiphase OH and O 3 oxidation reactions with atmospheric organic aerosol (OA) can influence particle physicochemical properties including composition, morphology, and lifetime. Chemical aging of initially insoluble or low-soluble single-component OA by OH and O 3 can increase their water solubility and hygroscopicity, making them more active as cloud condensation nuclei (CCN) and susceptible to wet deposition. However, an outstanding problem is whether the effects of chemical aging on their CCN activity are preserved when mixed with other organic or inorganic compounds exhibiting greater water solubility. In this work, the CCN activity of laboratory-generated biomass burning aerosol (BBA) surrogate particlesmore » exposed to OH and O 3 is evaluated by determining the hygroscopicity parameter, κ, as a function of particle type, mixing state, and OH and O 3 exposure applying a CCN counter (CCNc) coupled to an aerosol flow reactor (AFR). Levoglucosan (LEV), 4-methyl-5-nitrocatechol (MNC), and potassium sulfate (KS) serve as representative BBA compounds that exhibit different hygroscopicity, water solubility, chemical functionalities, and reactivity with OH radicals, and thus exemplify the complexity of mixed inorganic/organic aerosol in the atmosphere. The CCN activities of all of the particles were unaffected by O 3 exposure. Following exposure to OH, κ of MNC was enhanced by an order of magnitude, from 0.009 to ~ 0.1, indicating that chemically aged MNC particles are better CCN and more prone to wet deposition than pure MNC particles. No significant enhancement in κ was observed for pure LEV particles following OH exposure. κ of the internally mixed particles was not affected by OH oxidation. Furthermore, the CCN activity of OH-exposed MNC-coated KS particles is similar to the OH unexposed atomized 1 : 1 by mass MNC : KS binary-component particles. Our results strongly suggest that when OA is dominated by water-soluble organic carbon (WSOC) or inorganic ions

  13. Chemical aging of single and multicomponent biomass burning aerosol surrogate particles by OH: implications for cloud condensation nucleus activity

    DOE PAGES

    Slade, J. H.; Thalman, R.; Wang, J.; ...

    2015-09-14

    Multiphase OH and O 3 oxidation reactions with atmospheric organic aerosol (OA) can influence particle physicochemical properties including composition, morphology, and lifetime. Chemical aging of initially insoluble or low-soluble single-component OA by OH and O 3 can increase their water solubility and hygroscopicity, making them more active as cloud condensation nuclei (CCN) and susceptible to wet deposition. However, an outstanding problem is whether the effects of chemical aging on their CCN activity are preserved when mixed with other organic or inorganic compounds exhibiting greater water solubility. In this work, the CCN activity of laboratory-generated biomass burning aerosol (BBA) surrogate particlesmore » exposed to OH and O 3 is evaluated by determining the hygroscopicity parameter, κ, as a function of particle type, mixing state, and OH and O 3 exposure applying a CCN counter (CCNc) coupled to an aerosol flow reactor (AFR). Levoglucosan (LEV), 4-methyl-5-nitrocatechol (MNC), and potassium sulfate (KS) serve as representative BBA compounds that exhibit different hygroscopicity, water solubility, chemical functionalities, and reactivity with OH radicals, and thus exemplify the complexity of mixed inorganic/organic aerosol in the atmosphere. The CCN activities of all of the particles were unaffected by O 3 exposure. Following exposure to OH, κ of MNC was enhanced by an order of magnitude, from 0.009 to ~ 0.1, indicating that chemically aged MNC particles are better CCN and more prone to wet deposition than pure MNC particles. No significant enhancement in κ was observed for pure LEV particles following OH exposure. κ of the internally mixed particles was not affected by OH oxidation. Furthermore, the CCN activity of OH-exposed MNC-coated KS particles is similar to the OH unexposed atomized 1 : 1 by mass MNC : KS binary-component particles. Our results strongly suggest that when OA is dominated by water-soluble organic carbon (WSOC) or inorganic ions

  14. Active Brownian Particles. From Individual to Collective Stochastic Dynamics

    NASA Astrophysics Data System (ADS)

    Romanczuk, P.; Bär, M.; Ebeling, W.; Lindner, B.; Schimansky-Geier, L.

    2012-03-01

    We review theoretical models of individual motility as well as collective dynamics and pattern formation of active particles. We focus on simple models of active dynamics with a particular emphasis on nonlinear and stochastic dynamics of such self-propelled entities in the framework of statistical mechanics. Examples of such active units in complex physico-chemical and biological systems are chemically powered nano-rods, localized patterns in reaction-diffusion system, motile cells or macroscopic animals. Based on the description of individual motion of point-like active particles by stochastic differential equations, we discuss different velocity-dependent friction functions, the impact of various types of fluctuations and calculate characteristic observables such as stationary velocity distributions or diffusion coefficients. Finally, we consider not only the free and confined individual active dynamics but also different types of interaction between active particles. The resulting collective dynamical behavior of large assemblies and aggregates of active units is discussed and an overview over some recent results on spatiotemporal pattern formation in such systems is given.

  15. Particle size of calcium carbonate does not affect apparent and standardized total tract digestibility of calcium, retention of calcium, or growth performance of growing pigs.

    PubMed

    Merriman, L A; Stein, H H

    2016-09-01

    Two experiments were conducted to evaluate particle size of calcium carbonate used in diets fed to growing pigs. Experiment 1 was conducted to determine apparent total tract digestibility (ATTD), standardized total tract digestibility (STTD), and retention of Ca among diets containing calcium carbonate produced to different particle sizes, and Exp. 2 was conducted to determine if growth performance of weanling pigs is affected by particle size of calcium carbonate. In Exp. 1, 4 diets based on corn and potato protein isolate were formulated to contain 0.70% Ca and 0.33% standardized total tract digestible P, but the calcium carbonate used in the diets was ground to 4 different particle sizes (200, 500, 700, or 1,125 μm). A Ca-free diet was formulated to determine basal endogenous losses of Ca. In Exp. 2, 4 diets were based on corn and soybean meal and the only difference among diets was that each diet contained calcium carbonate ground to the 4 particle sizes used in Exp. 1. In Exp. 1, 40 barrows (15.42 ± 0.70 kg initial BW) were allotted to the 5 diets with 8 replicate pigs per diet using a randomized complete block design, and in Exp. 2, 128 pigs with an initial BW of 9.61 ± 0.09 kg were randomly allotted to 4 experimental diets. Results of Exp. 1 indicated that basal endogenous losses of Ca were 0.329 g/kg DMI. The ATTD of Ca was 70.0 ± 3.2, 74.3 ± 2.7, 70.0 ± 2.9, and 72.1 ± 2.7 and the STTD of Ca was 74.2 ± 3.2, 78.5 ± 2.7, 74.1 ± 2.9, and 76.2 ± 2.7 for calcium carbonate ground to 200, 500, 700, or 1,125 μm, respectively. Retention of Ca was 67.4 ± 3.1, 70.4 ± 2.6, 63.9 ± 2.8, and 67.2 ± 2.2 for diets containing calcium carbonate ground to 200, 500, 700, or 1,125 μm, respectively. There were no differences among diets for ATTD of Ca, STTD of Ca, or retention of Ca. The ATTD of P was 64.5 ± 1.7, 66.8 ± 2.6, 64.2 ± 3.0, and 63.2 ± 1.7% and retention of P was 61.4 ± 1.4, 63.8 ± 2.8, 61.9 ± 2.8, and 60.9 ± 1.5 for diets containing calcium

  16. Adsorption of metal ions by pecan shell-based granular activated carbons.

    PubMed

    Bansode, R R; Losso, J N; Marshall, W E; Rao, R M; Portier, R J

    2003-09-01

    The present investigation was undertaken to evaluate the adsorption effectiveness of pecan shell-based granular activated carbons (GACs) in removing metal ions (Cu(2+), Pb(2+), Zn(2+)) commonly found in municipal and industrial wastewater. Pecan shells were activated by phosphoric acid, steam or carbon dioxide activation methods. Metal ion adsorption of shell-based GACs was compared to the metal ion adsorption of a commercial carbon, namely, Calgon's Filtrasorb 200. Adsorption experiments were conducted using solutions containing all three metal ions in order to investigate the competitive effects of the metal ions as would occur in contaminated wastewater. The results obtained from this study showed that acid-activated pecan shell carbon adsorbed more lead ion and zinc ion than any of the other carbons, especially at carbon doses of 0.2-1.0%. However, steam-activated pecan shell carbon adsorbed more copper ion than the other carbons, particularly using carbon doses above 0.2%. In general, Filtrasorb 200 and carbon dioxide-activated pecan shell carbons were poor metal ion adsorbents. The results indicate that acid- and steam-activated pecan shell-based GACs are effective metal ion adsorbents and can potentially replace typical coal-based GACs in treatment of metal contaminated wastewater.

  17. Superfine powdered activated carbon (S-PAC) coatings on microfiltration membranes: Effects of milling time on contaminant removal and flux.

    PubMed

    Amaral, Pauline; Partlan, Erin; Li, Mengfei; Lapolli, Flavio; Mefford, O Thompson; Karanfil, Tanju; Ladner, David A

    2016-09-01

    In microfiltration processes for drinking water treatment, one method of removing trace contaminants is to add powdered activated carbon (PAC). Recently, a version of PAC called superfine PAC (S-PAC) has been under development. S-PAC has a smaller particle size and thus faster adsorption kinetics than conventionally sized PAC. Membrane coating performance of various S-PAC samples was evaluated by measuring adsorption of atrazine, a model micropollutant. S-PACs were created in-house from PACs of three different materials: coal, wood, and coconut shell. Milling time was varied to produce S-PACs pulverized with different amounts of energy. These had different particles sizes, but other properties (e.g. oxygen content), also differed. In pure water the coal based S-PACs showed superior atrazine adsorption; all milled carbons had over 90% removal while the PAC had only 45% removal. With addition of calcium and/or NOM, removal rates decreased, but milled carbons still removed more atrazine than PAC. Oxygen content and specific external surface area (both of which increased with longer milling times) were the most significant predictors of atrazine removal. S-PAC coatings resulted in loss of filtration flux compared to an uncoated membrane and smaller particles caused more flux decline than larger particles; however, the data suggest that NOM fouling is still more of a concern than S-PAC fouling. The addition of calcium improved the flux, especially for the longer-milled carbons. Overall the data show that when milling S-PAC with different levels of energy there is a tradeoff: smaller particles adsorb contaminants better, but cause greater flux decline. Fortunately, an acceptable balance may be possible; for example, in these experiments the coal-based S-PAC after 30 min of milling achieved a fairly high atrazine removal (overall 80%) with a fairly low flux reduction (under 30%) even in the presence of NOM. This suggests that relatively short duration (low energy

  18. Phenol adsorption by activated carbon produced from spent coffee grounds.

    PubMed

    Castro, Cínthia S; Abreu, Anelise L; Silva, Carmen L T; Guerreiro, Mário C

    2011-01-01

    The present work highlights the preparation of activated carbons (ACs) using spent coffee grounds, an agricultural residue, as carbon precursor and two different activating agents: water vapor (ACW) and K(2)CO(3) (ACK). These ACs presented the microporous nature and high surface area (620-950 m(2) g(-1)). The carbons, as well as a commercial activated carbon (CAC) used as reference, were evaluated as phenol adsorbent showing high adsorption capacity (≈150 mg g(-1)). The investigation of the pH solution in the phenol adsorption was also performed. The different activating agents led to AC with distinct morphological properties, surface area and chemical composition, although similar phenol adsorption capacity was verified for both prepared carbons. The production of activated carbons from spent coffee grounds resulted in promising adsorbents for phenol removal while giving a noble destination to the residue.

  19. Activated carbon coated palygorskite as adsorbent by activation and its adsorption for methylene blue.

    PubMed

    Zhang, Xianlong; Cheng, Liping; Wu, Xueping; Tang, Yingzhao; Wu, Yucheng

    2015-07-01

    An activation process for developing the surface and porous structure of palygorskite/carbon (PG/C) nanocomposite using ZnCl2 as activating agent was investigated. The obtained activated PG/C was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field-emission scanning electron microscopy (SEM), and Brunauer-Emmett-Teller analysis (BET) techniques. The effects of activation conditions were examined, including activation temperature and impregnation ratio. With increased temperature and impregnation ratio, the collapse of the palygorskite crystal structure was found to accelerate and the carbon coated on the surface underwent further carbonization. XRD and SEM data confirmed that the palygorskite structure was destroyed and the carbon structure was developed during activation. The presence of the characteristic absorption peaks of CC and C-H vibrations in the FTIR spectra suggested the occurrence of aromatization. The BET surface area improved by more than 11-fold (1201 m2/g for activated PG/C vs. 106 m2/g for PG/C) after activation, and the material appeared to be mainly microporous. The maximum adsorption capacity of methylene blue onto the activated PG/C reached 351 mg/g. The activated PG/C demonstrated better compressive strength than activated carbon without palygorskite clay. Copyright © 2015. Published by Elsevier B.V.

  20. Mesoporous activated carbon from corn stalk core for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Li, Yi; Li, Chun; Qi, Hui; Yu, Kaifeng; Liang, Ce

    2018-04-01

    A novel mesoporous activated carbon (AC) derived from corn stalk core is prepared via a facile and effective method which including the decomposition and carbonization of corn stalk core under an inert gas atmosphere and further activation process with KOH solution. The mesoporous activated carbon (AC) is characterized by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Brunauer-Emmett-Teller (BET) measurements. These biomass waste derived from activated carbon is proved to be promising anode materials for high specific capacity lithium ion batteries. The activated carbon anode possesses excellent reversible capacity of 504 mAh g-1 after 100 cycles at 0.2C. Compared with the unactivated carbon (UAC), the electrochemical performance of activated carbon is significantly improved due to its mesoporous structure.

  1. Anti-bacteria activity of carbon nanotubes grown on trimetallic catalyst

    NASA Astrophysics Data System (ADS)

    Ibrahim, S. O.; Abdulkareem, A. S.; Isah, K. U.; Ahmadu, U.; Bankole, M. T.; Kariim, I.

    2018-06-01

    Trimetallic catalyst was prepared using wet impregnation method to produce carbon nanotubes (CNTs) through the method of catalytic chemical vapor deposition (CCVD). Characterization of the developed catalyst and CNTs were carried out using thermogravimetric analysis (TGA), x-ray diffraction (XRD), specific surface area Brunauer-Emmett-Teller (BET), Fourier-transform infrared spectroscopy (FTIR), high-resolution scanning electron microscopy (HRSEM)/energy dispersive x-ray spectroscopy (EDS) and high-resolution transmission electron microscopy (HRTEM)/selected area electron diffraction (SAED). The BET and TGA analysis indicated that the catalyst has a high surface area and is thermally stable. The FTIR of the developed catalyst shows notable functional group with presence of unbound water. The HRSEM of the catalyst revealed agglomerated, homogeneous and porous particles while the HRSEM/HRTEM of the produced CNTs gave the formation of long strand of multiwalled carbon nanotubes (MWCNTs), and homogeneous crystalline fringe like structure with irregular diameter. EDS revealed the dominance of carbon in the elemental composition. XRD/SAED patterns of the catalyst suggest high dispersion of the metallic particles in the catalyst mixture while that of the CNTs confirmed that the produced MWCNTs were highly graphitized and crystalline in nature with little structural defects. The anti-bacteria activity of the produced MWCNTs on Klebsiella pneumoneae, Escherichia coli, and Pseudomonas aeruginosa was also carried out. It was observed that the produced MWCNTs have an inhibitory property on bacteria; Escherichia coli and Klebsiella pneumoneae from zero day ( and ) through to twelfth day (Nil count) respectively. It has no effect on Pseudomonas aeruginosa with too numerous to count at zero-sixth day, but a breakdown in its growth at ninth-twelfth day (). This study implied that MWCNTs with varying diameter and well-ordered nano-structure can be produced from catalyst via CCVD

  2. Characterization of exposures to nanoscale particles and fibers during solid core drilling of hybrid carbon nanotube advanced composites.

    PubMed

    Bello, Dhimiter; Wardle, Brian L; Zhang, Jie; Yamamoto, Namiko; Santeufemio, Christopher; Hallock, Marilyn; Virji, M Abbas

    2010-01-01

    This work investigated exposures to nanoparticles and nanofibers during solid core drilling of two types of advanced carbon nanotube (CNT)-hybrid composites: (1) reinforced plastic hybrid laminates (alumina fibers and CNT); and (2) graphite-epoxy composites (carbon fibers and CNT). Multiple real-time instruments were used to characterize the size distribution (5.6 nm to 20 microm), number and mass concentration, particle-bound polyaromatic hydrocarbons (b-PAHs), and surface area of airborne particles at the source and breathing zone. Time-integrated samples included grids for electron microscopy characterization of particle morphology and size resolved (2 nm to 20 microm) samples for the quantification of metals. Several new important findings herein include generation of airborne clusters of CNTs not seen during saw-cutting of similar composites, fewer nanofibers and respirable fibers released, similarly high exposures to nanoparticles with less dependence on the composite thickness, and ultrafine (< 5 nm) aerosol originating from thermal degradation of the composite material.

  3. Light Absorption Enhancement of Black Carbon Aerosol Constrained by Particle Morphology.

    PubMed

    Wu, Yu; Cheng, Tianhai; Liu, Dantong; Allan, James D; Zheng, Lijuan; Chen, Hao

    2018-06-19

    The radiative forcing of black carbon aerosol (BC) is one of the largest sources of uncertainty in climate change assessments. Contrasting results of BC absorption enhancement ( E abs ) after aging are estimated by field measurements and modeling studies, causing ambiguous parametrizations of BC solar absorption in climate models. Here we quantify E abs using a theoretical model parametrized by the complex particle morphology of BC in different aging scales. We show that E abs continuously increases with aging and stabilizes with a maximum of ∼3.5, suggesting that previous seemingly contrast results of E abs can be explicitly described by BC aging with corresponding particle morphology. We also report that current climate models using Mie Core-Shell model may overestimate E abs at a certain aging stage with a rapid rise of E abs , which is commonly observed in the ambient. A correction coefficient for this overestimation is suggested to improve model predictions of BC climate impact.

  4. Evaluation of dispersion methods for enumeration of microorganisms from peat and activated carbon biofilters treating volatile organic compounds.

    PubMed

    Khammar, Nadia; Malhautier, Luc; Degrange, Valérie; Lensi, Robert; Fanlo, Jean-Louis

    2004-01-01

    To enumerate microorganisms having colonized biofilters treating volatile organic compounds, it is necessary firstly to evaluate dispersion methods. Crushing, shaking and sonication were then tested for the removal of microflora from biofilters packing materials (peat and activated carbon). Continuous or discontinuous procedures, and addition of glass beads had no effect on the number of microorganisms removed from peat particles. The duration of treatment also had no effect for shaking and crushing, but the number of microorganisms after 60 min of treatment with ultrasound was significantly higher than that obtained after 0.5 min. The comparison between these methods showed that crushing was the most efficient for the removal of microorganisms from both peat and activated carbon. The comparison between three chemical dispersion agents showed that 1% Na-pyrophosphate was less efficient, compared with 200 mM phosphate buffer or 1% Na-hexametaphosphate. To optimize the cultivation of microorganisms, three different agar media were compared. Tryptic soy agar tenfold diluted (TSA 1/10) was the most suitable medium for the culture of microflora from a peat biofilter. For the activated carbon biofilter, there was no significant difference between Luria Bertoni, TSA 1/10, and plate count agar. The optimized extraction and enumeration protocols were used to perform a quantitative characterization of microbial populations in an operating laboratory activated carbon biofilter and in two parallel peat biofilters.

  5. Study the effect of active carbon modified using HNO3 for carbon electrodes in capacitive deionization system

    NASA Astrophysics Data System (ADS)

    Blegur, Ernes Josias; Endarko

    2017-01-01

    Carbon electrodes prepared with crosslink method for desalination purpose has been synthesized and characterized. The carbon electrodes were synthesized with activated carbon (700 - 1400 m2/g) and polyvinyl alcohol (PVA) as a binder using crosslink method with temperature crosslink at 120°C. Electrochemical properties of carbon electrodes were examined using electrical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The proposed study was to measure the salt-removal percentage of 330 µS/cm NaCl using a capacitive deionization (CDI) unit cell prepared with two pairs of carbon electrodes. The applied potential of 2.0 V and a flow rate of 25 mL/min were used to desalination tests. The result showed that the greatest value of the percentage of salt-removal was achieved at 36.1% for the carbon electrodes with Active Carbon Modified (ACM) while the salt-removal percentage for the Active Carbon (AC) electrodes only at 22%. The fact indicates that the active carbon modified using HNO3 can improve the efficiency of CDI about 14%.

  6. 78 FR 13894 - Certain Activated Carbon From China

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-01

    ... INTERNATIONAL TRADE COMMISSION [Investigation No. 731-TA-1103 (Review)] Certain Activated Carbon From China Determination On the basis of the record \\1\\ developed in the subject five-year review, the... (February 2013), entitled Certain Activated Carbon from China: Investigation No. 731-TA-1103 (Review). By...

  7. Responses of Lumbriculus variegatus to activated carbon amendments in uncontaminated sediments.

    PubMed

    Nybom, Inna; Werner, David; Leppänen, Matti T; Siavalas, George; Christanis, Kimon; Karapanagioti, Hrissi K; Kukkonen, Jussi V K; Akkanen, Jarkko

    2012-12-04

    Activated carbon (AC) amendment is a recently developed sediment remediation method. The strong hydrophobic organic contaminant sorption efficiency of AC has been shown in several studies, but effects on benthic organisms require more investigation. The AC induced effects on egestion rate, growth and reproduction of Lumbriculus variegatus were studied by applying bituminous coal based AC in three different particle size fractions, namely <63 μm (90%, AC(p)), 63-200 μm (AC(m)) and 1000 μm (AC(g)), to natural uncontaminated (HS) and artificial sediment (AS). Egestion rate, growth and reproduction decreased with increasing AC concentration and finer AC particle fractions, effects being stronger on HS than on AS sediment. Lipid content in AS was reduced already at the lowest AC doses applied (AC(p) and AC(m) 0.05%, AC(g) 0.25%). In addition, hormesis-like response was observed in growth (AS) and reproduction (AS, HS) indicating that AC may disturb organisms even at very low doses. Potential ecological effects need to be further evaluated in an amendment- and site-specific manner.

  8. Activated Carbon Modified with Copper for Adsorption of Propanethiol

    PubMed Central

    Moreno-Piraján, Juan Carlos; Tirano, Joaquín; Salamanca, Brisa; Giraldo, Liliana

    2010-01-01

    Activated carbons were characterized texturally and chemically before and after treatment, using surface area determination in the BET model, Boehm titration, TPR, DRX and immersion calorimetry. The adsorption capacity and the kinetics of sulphur compound removal were determined by gas chromatography. It was established that the propanethiol retention capacity is dependent on the number of oxygenated groups generated on the activated carbon surface and that activated carbon modified with CuO at 0.25 M shows the highest retention of propanethiol. Additionally is proposed a mechanism of decomposition of propenothiol with carbon-copper system. PMID:20479992

  9. Natural gas storage with activated carbon from a bituminous coal

    USGS Publications Warehouse

    Sun, Jielun; Rood, M.J.; Rostam-Abadi, M.; Lizzio, A.A.

    1996-01-01

    Granular activated carbons ( -20 + 100 mesh; 0.149-0.84 mm) were produced by physical activation and chemical activation with KOH from an Illinois bituminous coal (IBC-106) for natural gas storage. The products were characterized by BET surface area, micropore volume, bulk density, and methane adsorption capacities. Volumetric methane adsorption capacities (Vm/Vs) of some of the granular carbons produced by physical activation are about 70 cm3/cm3 which is comparable to that of BPL, a commercial activated carbon. Vm/Vs values above 100 cm3/cm3 are obtainable by grinding the granular products to - 325 mesh (<0.044 mm). The increase in Vm/Vs is due to the increase in bulk density of the carbons. Volumetric methane adsorption capacity increases with increasing pore surface area and micropore volume when normalizing with respect to sample bulk volume. Compared with steam-activated carbons, granular carbons produced by KOH activation have higher micropore volume and higher methane adsorption capacities (g/g). Their volumetric methane adsorption capacities are lower due to their lower bulk densities. Copyright ?? 1996 Elsevier Science Ltd.

  10. Asphalt-derived high surface area activated porous carbons for carbon dioxide capture.

    PubMed

    Jalilov, Almaz S; Ruan, Gedeng; Hwang, Chih-Chau; Schipper, Desmond E; Tour, Josiah J; Li, Yilun; Fei, Huilong; Samuel, Errol L G; Tour, James M

    2015-01-21

    Research activity toward the development of new sorbents for carbon dioxide (CO2) capture have been increasing quickly. Despite the variety of existing materials with high surface areas and high CO2 uptake performances, the cost of the materials remains a dominant factor in slowing their industrial applications. Here we report preparation and CO2 uptake performance of microporous carbon materials synthesized from asphalt, a very inexpensive carbon source. Carbonization of asphalt with potassium hydroxide (KOH) at high temperatures (>600 °C) yields porous carbon materials (A-PC) with high surface areas of up to 2780 m(2) g(-1) and high CO2 uptake performance of 21 mmol g(-1) or 93 wt % at 30 bar and 25 °C. Furthermore, nitrogen doping and reduction with hydrogen yields active N-doped materials (A-NPC and A-rNPC) containing up to 9.3% nitrogen, making them nucleophilic porous carbons with further increase in the Brunauer-Emmett-Teller (BET) surface areas up to 2860 m(2) g(-1) for A-NPC and CO2 uptake to 26 mmol g(-1) or 114 wt % at 30 bar and 25 °C for A-rNPC. This is the highest reported CO2 uptake among the family of the activated porous carbonaceous materials. Thus, the porous carbon materials from asphalt have excellent properties for reversibly capturing CO2 at the well-head during the extraction of natural gas, a naturally occurring high pressure source of CO2. Through a pressure swing sorption process, when the asphalt-derived material is returned to 1 bar, the CO2 is released, thereby rendering a reversible capture medium that is highly efficient yet very inexpensive.

  11. Adsorption of aromatic compounds by carbonaceous adsorbents: a comparative study on granular activated carbon, activated carbon fiber, and carbon nanotubes.

    PubMed

    Zhang, Shujuan; Shao, Ting; Kose, H Selcen; Karanfil, Tanju

    2010-08-15

    Adsorption of three aromatic organic compounds (AOCs) by four types of carbonaceous adsorbents [a granular activated carbon (HD4000), an activated carbon fiber (ACF10), two single-walled carbon nanotubes (SWNT, SWNT-HT), and a multiwalled carbon nanotube (MWNT)] with different structural characteristics but similar surface polarities was examined in aqueous solutions. Isotherm results demonstrated the importance of molecular sieving and micropore effects in the adsorption of AOCs by carbonaceous porous adsorbents. In the absence of the molecular sieving effect, a linear relationship was found between the adsorption capacities of AOCs and the surface areas of adsorbents, independent of the type of adsorbent. On the other hand, the pore volume occupancies of the adsorbents followed the order of ACF10 > HD4000 > SWNT > MWNT, indicating that the availability of adsorption site was related to the pore size distributions of the adsorbents. ACF10 and HD4000 with higher microporous volumes exhibited higher adsorption affinities to low molecular weight AOCs than SWNT and MWNT with higher mesopore and macropore volumes. Due to their larger pore sizes, SWNTs and MWNTs are expected to be more efficient in adsorption of large size molecules. Removal of surface oxygen-containing functional groups from the SWNT enhanced adsorption of AOCs.

  12. Investigating effectiveness of activated carbons of natural sources on various supercapacitors

    NASA Astrophysics Data System (ADS)

    Faisal, Md. Shahnewaz Sabit; Rahman, Muhammad M.; Asmatulu, Ramazan

    2016-04-01

    Activated carbon can be produced from natural sources, such as pistachio and acorn shells, which can be an inexpensive and sustainable sources of natural wastes for the energy storage devices, such as supercapacitors. The carbonaceous materials used in this study were carbonized at the temperatures of 700°C and 900°C after the stabilization process at 240°C for two hours. These shells showed approximately 60% carbon yield. Carbonized nutshells were chemically activated using1wt% potassium hydroxide (KOH). Activated carbon powders with polyvinylidene fluoride (PVdF) were used to construct carbon electrodes. A 1M of tetraethylammonium tetrafluoroborate (TEABF4) and propylene carbonate (PC) were used as electrolytes. Electrochemical techniques, such as cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used for the characterization of the supercapacitors. Scanning electron microscopy (SEM) was used to inspect the surface texture of the activated carbons. Activated pistachio shells carbonized at 700°C showed more porous surface texture than those carbonized at 900°C. Effects of the carbonization temperatures were studied for their electrochemical characteristics. The shells carbonized at 700°C showed better electrochemical characteristics compared to those carbonized at 900°C. The test results provided about 27,083 μF/g specific capacitance at a scan rate of 10mV/s. This study showed promising results for using these activated carbons produced from the natural wastes for supercapacitor applications.

  13. Mixing and demixing of binary mixtures of polar chiral active particles.

    PubMed

    Ai, Bao-Quan; Shao, Zhi-Gang; Zhong, Wei-Rong

    2018-05-17

    We study a binary mixture of polar chiral (counterclockwise or clockwise) active particles in a two-dimensional box with periodic boundary conditions. Besides the excluded volume interactions between particles, the particles are also subjected to the polar velocity alignment. From the extensive Brownian dynamics simulations, it is found that the particle configuration (mixing or demixing) is determined by the competition between the chirality difference and the polar velocity alignment. When the chirality difference competes with the polar velocity alignment, the clockwise particles aggregate in one cluster and the counterclockwise particles aggregate in the other cluster; thus, the particles are demixed and can be separated. However, when the chirality difference or the polar velocity alignment is dominant, the particles are mixed. Our findings could be used for the experimental pursuit of the separation of binary mixtures of chiral active particles.

  14. Markedly enhanced direct radiative forcing of black carbon particles under polluted urban environments

    NASA Astrophysics Data System (ADS)

    Peng, Jianfei; Hu, Min; Guo, Song; Du, Zhuofei; Zheng, Jing; Shang, Dongjie; Zamora, Misti; Zeng, Liming; Shao, Min; Wu, Yusheng; Zheng, Jun; Wang, Yuan; Collins, Don; Zhang, Renyi

    2016-04-01

    Black carbon (BC) particles, produced from incomplete fossil fuel combustion and biomass burning, are ubiquitous in the atmosphere and have profound impacts on air quality, human health, weather, and climate. For example, in areas identified as aerosol hotspots, which include many urban centers and megacities worldwide, solar heating by BC particles has been shown to be comparable to warming due to the greenhouse gases2. Although BC represents a key short-lived climate forcer, its direct radiative forcing remains highly uncertain. In particular, the available results of absorption enhancement of BC particles during atmospheric aging are conflicting from the previous studies, leading to a large uncertainty in global radiative transfer calculation. Here, we quantified the aging and variation in the optical properties of BC particles under ambient conditions in Beijing, China and Houston, US, using a novel chamber approach. BC aging exhibits two distinct stages - initial transformation from a fractal to spherical morphology with little absorption variation and the subsequent growth of fully compact particles with a maximum absorption enhancement factor of 2.4. The variation in BC direct radiative forcing is highly dependent of the rate and timescale of aging, with an estimated increase of 0.45 (0.21 - 0.80) W m-2 from fresh to fully aged particles. Our results reveal a high climatic impact in polluted environments due to rapid aging and a clear distinction between urban cities in developed and developing countries for BC particles, highlighting a larger than recognized co-benefit in air quality improvement and climate protection by BC mediation.

  15. Mean first passage time of active Brownian particle in one dimension

    NASA Astrophysics Data System (ADS)

    Scacchi, A.; Sharma, A.

    2018-02-01

    We investigate the mean first passage time of an active Brownian particle in one dimension using numerical simulations. The activity in one dimension is modelled as a two state model; the particle moves with a constant propulsion strength but its orientation switches from one state to other as in a random telegraphic process. We study the influence of a finite resetting rate r on the mean first passage time to a fixed target of a single free active Brownian particle and map this result using an effective diffusion process. As in the case of a passive Brownian particle, we can find an optimal resetting rate r* for an active Brownian particle for which the target is found with the minimum average time. In the case of the presence of an external potential, we find good agreement between the theory and numerical simulations using an effective potential approach.

  16. Ultrafine particle concentration and new particle formation in a coastal arid environment

    NASA Astrophysics Data System (ADS)

    Alfoldy, Balint; Kotob, Mohamed; Obbard, Jeffrey P.

    2017-04-01

    Arid environments can be generally characterised by high coarse aerosol load due to the wind-driven erosion of the upper earth crust (i.e. Aeolian dust). On the other hand, anthropogenic activities and/or natural processes also generate significant numbers of particles in the ultrafine size range. Ultrafine particles (also referred as nano-particles) is considered as aerosol particles with the diameter less than 100 nm irrespectively their chemical composition. Due to their small size, these particles represent negligible mass portion in the total atmospheric particulate mass budget. On the other hand, these particles represent the majority of the total particle number budget and have the major contribution in the total aerosol surface distribution. Ultrafine particles are characterised by high mobility (diffusion) and low gravitational settling velocity. Consequently, these particles can be transported long distances and their atmospheric lifetime is relatively high (i.e. in the Accumulation Mode). Ultrafine particles play important role in the atmosphere as they take part in the atmospheric chemistry (high surface), impact the climate (sulphate vs. black carbon), and implies significant health effects due to their deep lung penetration and high mobility in the body. The Atmospheric Laboratory of Qatar University is conducting real-time monitoring of ultrafine particles and regularly taking aerosol samples for chemical analysis at the university campus. In this paper, recent results are presented regarding the size distribution and chemical composition of the ultrafine aerosol particles. Based on the concentration variation in time, sources of ultrafine particles can be clearly separated from the sources of fine or coarse particles. Several cases of new particle formation events have been observed and demonstrated in the paper, however, the precursors of the secondary aerosol particles are still unknown. Literature references suggest that among the sulphuric acid

  17. Water-assisted growth of graphene-carbon nanotube hybrids in plasma

    NASA Astrophysics Data System (ADS)

    Tewari, Aarti; Ghosh, Santanu; Srivastava, Pankaj

    2018-04-01

    The enhanced growth of graphene-carbon nanotube (CNT) hybrids in a hydrocarbon and hydrogen plasma assisted by water is numerically formulated. The catalyst activity and agglomeration of catalyst particles are the rate determining factors in the growth of hybrids and their constituents, i.e., the CNT and graphene. The water vapor concentration is varied to investigate its effect on the growth process. The enhanced catalyst activity on account of oxidation by hydroxyl ions of water to impede the agglomeration of catalyst particles and the removal of amorphous carbon through etching by hydrogen ions of water are seen to be the main driving forces behind the many fold increase in the dimensions of constituent nanostructures and the hybrids with water vapor concentration. Importantly, beyond a certain specific water vapor concentration, the growth rates dropped due to active oxidation of the catalyst particle.

  18. Characterization of typical metal particles during haze episodes in Shanghai, China.

    PubMed

    Li, Rui; Yang, Xin; Fu, Hongbo; Hu, Qingqing; Zhang, Liwu; Chen, Jianmin

    2017-08-01

    Aerosol particles were collected during three heavy haze episodes at Shanghai in the winter of 2013. Transmission electron microscopy (TEM) coupled with energy dispersive X-ray spectroscopy was used to study the morphology and speciation of typical metal particles at a single-particle level. In addition, time-of-flight aerosol mass spectrometry (ATOFMS) was applied to identify the speciation of the Fe-containing particles. TEM analysis indicated that various metal-containing particles were hosted by sulfates, nitrates, and oxides. Fe-bearing particles mainly originated from vehicle emissions and/or steel production. Pb-, Zn-, and Sb-bearing particles were mainly contributed by anthropogenic sources. Fe-bearing particles were clustered into six groups by ATOFMS: Fe-Carbon, Fe-Inorganic, Fe-Trace metal, Fe-CN, Fe-PO 3, and Fe-NO 3 . ATOFMS data suggested that Fe-containing particles corresponded to different origins, including industrial activities, resuspension of dusts, and vehicle emissions. Fe-Carbon and Fe-CN particles displayed significant diurnal variation, and high levels were observed during the morning rush hours. Fe-Inorganic and Fe-Trace metal particle levels peaked at night. Furthermore, Fe-Carbon and Fe-PO 3 were mainly concentrated in the fine particles. Fe-CN, Fe-Inorganic, and Fe-Trace metal exhibited bimodal distribution. The mixing state of the particles revealed that all Fe-bearing particles tended to be mixed with sulfate and nitrate. The data presented herein is essential for elucidating the origin, evolution processes, and health effects of metal-bearing particles. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. FENTON-DRIVEN REGENERATION OF GRANULAR ACTIVATED CARBON: A TECHNOLOGY OVERVIEW

    EPA Science Inventory

    A Fenton-driven mechanism for regenerating spent granular activated carbon (GAC) involves the combined, synergistic use of two reliable and well established treatment technologies - adsorption onto activated carbon and Fenton oxidation. During carbon adsorption treatment, enviro...

  20. DIESEL AND CARBON PARTICLES ENHANCE HOUSE DUST MITE-INDUCED PULMONARY HYPERSENSITIVITY IN BROWN NORWAY RATS

    EPA Science Inventory

    Diesel and Carbon Particles Enhance House Dust Mite-Induced Pulmonary Hypersensitivity in Brown Norway Rats. P. Singh1, M.J. Daniels2, D. Winsett2, J. Richards2, K. Crissman2, M. Madden2 and M.I. Gilmour2. 1NCSU, Raleigh, NC and 2 USEPA, Research Triangle Park, NC.

    Ep...

  1. Remarkable activity of nitrogen-doped hollow carbon spheres encapsulated Cu on synthesis of dimethyl carbonate: Role of effective nitrogen

    NASA Astrophysics Data System (ADS)

    Li, Haixia; Zhao, Jinxian; Shi, Ruina; Hao, Panpan; Liu, Shusen; Li, Zhong; Ren, Jun

    2018-04-01

    A critical aspect in the improvement of the catalytic performance of Cu-based catalysts for the synthesis of dimethyl carbonate (DMC) is the development of an appropriate support. In this work, nitrogen-doped hollow carbon spheres (NHCSs), with 240 nm average diameter, 17 nm shell thickness, uniform mesoporous structure and a specific surface area of 611 m2 g-1, were prepared via a two-step Stӧber method. By varying the quantity of nitrogen-containing phenols used in the preparation it has been possible to control the nitrogen content and, consequently, the sphericity of the NHCSs. It was found that perfect spheres were obtained for nitrogen contents below 5.4 wt.%. The catalysts (Cu@NHCSs) were prepared by the hydrothermal impregnation method. The catalytic activity towards DMC synthesis was notably enhanced due to the immobilization effect on Cu particles and the enhanced electron transfer effect exercised by the effective nitrogen species, including pyridinic-N and graphitic-N. When the average size of the copper nanoparticles was 7.4 nm and the nitrogen content was 4.0 wt.%, the values of space-time yield of DMC and of turnover frequency (TOF) reached 1528 mg/(g h) and 11.0 h-1, respectively. The TOF value of Cu@NHCSs was 6 times higher than non-doped Cu@Carbon (2.1 h-1). The present work introduces the potential application of nitrogen-doped carbon materials and presents a novel procedure for the preparation of catalysts for DMC synthesis.

  2. Design of lithium cobalt oxide electrodes with high thermal conductivity and electrochemical performance using carbon nanotubes and diamond particles

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Lee, Eungje; Salgado, Ruben Arash; Lee, Byeongdu

    Thermal management remains one of the major challenges in the design of safe and reliable Li-ion batteries. We show that composite electrodes assembled from commercially available 100 μm long carbon nanotubes (CNTs) and LiCoO2 (LCO) particles demonstrate the in-plane thermal conductivity of 205.8 W/m*K. This value exceeds the thermal conductivity of dry conventional laminated electrodes by about three orders of magnitude. The cross-plane thermal conductivity of CNT-based electrodes is in the same range as thermal conductivities of conventional laminated electrodes. The CNT-based electrodes demonstrate a similar capacity to conventional laminated design electrodes, but revealed a better rate performance and stability.more » The introduction of diamond particles into CNT-based electrodes further improves the rate performance. Our lightweight, flexible electrode design can potentially be a general platform for fabricating polymer binder- and aluminum and copper current collector- free electrodes from a broad range of electrochemically active materials with efficient thermal management.« less

  3. Associations between fine particle, coarse particle, black carbon and hospital visits in a Chinese city.

    PubMed

    Wang, Xi; Chen, Renjie; Meng, Xia; Geng, Fuhai; Wang, Cuicui; Kan, Haidong

    2013-08-01

    China is one of the countries with the highest ambient particle levels in the world; however, there have been no epidemiologic studies examining the effects of fine particle (PM2.5), coarse particle (PM10-2.5) and black carbon (BC) simultaneously on morbidity outcomes. In this study, we conducted a time-series analysis to evaluate the acute effects of PM2.5, PM10-2.5, and BC on daily hospital visits in Shanghai, China. During our study period, the mean daily concentrations of PM2.5, PM10-2.5 and BC were 53.9 μg/m(3), 38.4 μg/m(3) and 3.9 μg/m(3), respectively. We found significant associations of PM2.5, PM 10-2.5, and BC with daily hospital visits. An inter-quartile range increase of the average concentrations of the current and previous days in PM2.5, PM10-2.5 and BC was associated with a 1.88% (95% CI: 0.69% to 3.06%), a 1.30% (95% CI: 0.25% to 2.34%) and a 1.33% (95% CI: 0.34% to 2.32%) increase in emergency-room visits, respectively. For outpatient visits, the corresponding estimated changes were -2.44% (95% CI: -6.62% to 1.74%), 1.09% (95% CI: -2.72% to 4.90%) and 3.34% (95% CI: 0.10% to 6.57%) respectively. The effects of BC were more robust than the effects of PM2.5 and PM10-2.5 in two-pollutant models. To our knowledge, this is the first study in China, or even in Asian developing countries, to report the effect of PM2.5, PM10-2.5, and BC simultaneously on morbidity. Our findings also suggest that BC could serve as a valuable air quality indicator that reflects the health risks of airborne particles. Copyright © 2013 Elsevier B.V. All rights reserved.

  4. Convective Self-Sustained Motion in Mixtures of Chemically Active and Passive Particles.

    PubMed

    Shklyaev, Oleg E; Shum, Henry; Yashin, Victor V; Balazs, Anna C

    2017-08-15

    We develop a model to describe the behavior of a system of active and passive particles in solution that can undergo spontaneous self-organization and self-sustained motion. The active particles are uniformly coated with a catalyst that decomposes the reagent in the surrounding fluid. The resulting variations in the fluid density give rise to a convective flow around the active particles. The generated fluid flow, in turn, drives the self-organization of both the active and passive particles into clusters that undergo self-sustained propulsion along the bottom wall of a microchamber. This propulsion continues until the reagents in the solution are consumed. Depending on the number of active and passive particles and the structure of the self-organized cluster, these assemblies can translate, spin, or remain stationary. We also illustrate a scenario in which the geometry of the container is harnessed to direct the motion of a self-organized, self-propelled cluster. The findings provide guidelines for creating autonomously moving active particles, or chemical "motors" that can transport passive cargo in microfluidic devices.

  5. Downward particle flux and carbon export in the Beaufort Sea, Arctic Ocean; the Malina experiment

    NASA Astrophysics Data System (ADS)

    Miquel, J.-C.; Gasser, B.; Martín, J.; Marec, C.; Babin, M.; Fortier, L.; Forest, A.

    2015-01-01

    As part of the international, multidisciplinary project Malina, downward particle fluxes were investigated by means of a drifting multi-sediment trap mooring deployed at three sites in the Canadian Beaufort Sea in late summer 2009. Mooring deployments lasted for 28-50 h and targeted the shelf-break and the slope along the Beaufort-Mackenzie continental margin, as well as the edge between the Mackenzie Shelf and the Amundsen Gulf. Besides analyses of C and N, the collected material was investigated for pigments, phyto- and microzooplankton, faecal pellets and swimmers. The measured fluxes were relatively low, in the range of 11-54 mg m-2 d-1 for the total mass, 1-15 mg C m-2 d-1 for organic carbon and 0.2-2.5 mg N m-2 d-1 for nitrogen. Comparison with a long-term trap dataset from the same sampling area showed that the short-term measurements were at the lower end of the high variability characterizing a rather high flux regime during the study period. The sinking material consisted of aggregates and particles that were characterized by the presence of hetero- and autotrophic microzooplankters and diatoms and by the corresponding pigment signatures. Faecal pellets contribution to sinking carbon flux was important, especially at depth where they represented up to 25% of the total carbon flux. The vertical distribution of different morphotypes of pellets showed a marked pattern with cylindrical faeces (produced by calanoid copepods) present mainly within the euphotic zone, whereas elliptical pellets (produced mainly by smaller copepods) were more abundant at mesopelagic depths. These features, together with the density of matter within the pellets, highlighted the role of the zooplankton community in the transformation of carbon issued from the primary production and the transition of that carbon from the productive surface zone to the Arctic Ocean's interior. Our data indicate that sinking carbon flux in this late summer period is primarily the result of a

  6. Effect of a nano-sized TiC particle addition on the flow-assisted corrosion resistance of SA 106B carbon steel

    NASA Astrophysics Data System (ADS)

    Park, Jin-Ju; Park, Eun-Kwang; Lee, Gyoung-Ja; Rhee, Chang-Kyu; Lee, Min-Ku

    2017-09-01

    Carbon steel with dispersed nano-sized TiC ceramic particles was fabricated by the ex-situ introduction of the particles into the melt, with the flow-assisted corrosion (FAC) resistance then investigated in the presence and absence of TiC nanoparticles using a once-through type of FAC loop test. From the potentiodynamic polarization curves, the current density at any given anodic potential was decreased and the open-circuit potential was increased by the addition of TiC nanoparticles. In addition, when the nano-sized TiC particles were added, the FAC rate was 1.38 times lower than that of carbon steel without TiC nanoparticles, indicating an improvement of the FAC resistance due to the homogeneous distribution of the TiC reinforcing nanoparticles.

  7. SEASONAL VARIATION OF THE PARTICLE SIZE DISTRIBUTION OF POLYCYCLIC AROMATIC HYDROCARBONS AND OF MAJOR AEROSOL SPECIES IN CLAREMONT, CALIFORNIA. (R827352C020)

    EPA Science Inventory

    As part of the Southern California Particle Center and Supersite (SCPCS) activities, we measured, during all seasons, particle size distributions of 12 priority pollutant polycyclic aromatic hydrocarbons (PAHs), concurrently with elemental carbon (EC), organic carbon (OC), sul...

  8. Single Particle Dynamic Imaging and Fe3+ Sensing with Bright Carbon Dots Derived from Bovine Serum Albumin Proteins

    NASA Astrophysics Data System (ADS)

    Yang, Qingxiu; Wei, Lin; Zheng, Xuanfang; Xiao, Lehui

    2015-12-01

    In this work, we demonstrated a convenient and green strategy for the synthesis of highly luminescent and water-soluble carbon dots (Cdots) by carbonizing carbon precursors, i.e., Bovine serum albumin (BSA) nanoparticles, in water solution. Without post surface modification, the as-synthesized Cdots exhibit fluorescence quantum yield (Q.Y.) as high as 34.8% and display superior colloidal stability not only in concentrated salt solutions (e.g. 2 M KCl) but also in a wide range of pH solutions. According to the FT-IR measurements, the Cdots contain many carboxyl groups, providing a versatile route for further chemical and biological functionalization. Through conjugation of Cdots with the transacting activator of transcription (TAT) peptide (a kind of cell penetration peptide (CPP)) derived from human immunodeficiency virus (HIV), it is possible to directly monitor the dynamic interactions of CPP with living cell membrane at single particle level. Furthermore, these Cdots also exhibit a dosage-dependent selectivity toward Fe3+ among other metal ions, including K+, Na+, Mg2+, Hg2+, Co2+, Cu2+, Pb2+ and Al3+. We believed that the Cdots prepared by this strategy would display promising applications in various areas, including analytical chemistry, nanomedicine, biochemistry and so on.

  9. DUSTER: collection of meteoric CaO and carbon smoke particles in the upper stratosphere .

    NASA Astrophysics Data System (ADS)

    Della Corte, V.; Rietmeijer, F. J. M.; Rotundi, A.; Ferrari, M.; Palumbo, P.

    Nanometer- to micrometer-size particles present in the upper stratosphere are a mixture of terrestrial and extra-terrestrial origins. They can be extraterrestrial particles condensed after meteor ablation. Meteoric dust in bolides is occasionally deposited into the lower stratosphere around 20 km altitude. Nanometer CaO and pure carbon smoke particles were collected at 38 km altitude in the upper stratosphere in the Arctic during June 2008 using DUSTER (Dust in the Upper Stratosphere Tracking Experiment and Retrieval), a balloon-borne instrument for the non-destructive collection of solid particles between 200 nm to 40 microns. We report the collection of micron sized CaCO_3 (calcite) grains. Their morphologies show evidence of melting and condensation after vaporization suggest at temperatures of approximately 3500 K. The formation environment of the collected grains was probably a dense dust cloud formed by the disintegration of a carbonaceous meteoroid during deceleration in the Earth� atmosphere. For the first time, DUSTER collected meteor ablation products that were presumably associated with the disintegration of a bolide crossing the Earth's atmosphere. The collected mostly CaO and pure carbon nanoparticles from the debris cloud of a fireball, included: 1) intact fragments; 2) quenched melted grains; and 3) vapor phase condensation products. The DUSTER project was funded by the Italian Space Agency (ASI), PRIN2008/MIUR (Ministero dell'Istruzione dell'Universitá e della Ricerca), PNRA 2013(Piano Nazionale Ricerca Antartide). CNES graciously provided this flight opportunity. We thank E. Zona and S. Inarta at the Laboratorio di Fisica Cosmica INAF, Osservatorio Astronomico di Capodimonte-Universitá di Napoli Parthenope. F.J.M.R. was supported by grant NNX07AI39G from the NASA Cosmochemistry Program. We thank three anonymous reviewers who assisted us in introducing our new instrument.

  10. Evidence for Reduced, Carbon-rich Regions in the Solar Nebula from an Unusual Cometary Dust Particle

    NASA Astrophysics Data System (ADS)

    De Gregorio, Bradley T.; Stroud, Rhonda M.; Nittler, Larry R.; Kilcoyne, A. L. David

    2017-10-01

    Geochemical indicators in meteorites imply that most formed under relatively oxidizing conditions. However, some planetary materials, such as the enstatite chondrites, aubrite achondrites, and Mercury, were produced in reduced nebular environments. Because of large-scale radial nebular mixing, comets and other Kuiper Belt objects likely contain some primitive material related to these reduced planetary bodies. Here, we describe an unusual assemblage in a dust particle from comet 81P/Wild 2 captured in silica aerogel by the NASA Stardust spacecraft. The bulk of this ˜20 μm particle is comprised of an aggregate of nanoparticulate Cr-rich magnetite, containing opaque sub-domains composed of poorly graphitized carbon (PGC). The PGC forms conformal shells around tiny 5-15 nm core grains of Fe carbide. The C, N, and O isotopic compositions of these components are identical within errors to terrestrial standards, indicating a formation inside the solar system. Magnetite compositions are consistent with oxidation of reduced metal, similar to that seen in enstatite chondrites. Similarly, the core-shell structure of the carbide + PGC inclusions suggests a formation via FTT reactions on the surface of metal or carbide grains in warm, reduced regions of the solar nebula. Together, the nanoscale assemblage in the cometary particle is most consistent with the alteration of primary solids condensed from a C-rich, reduced nebular gas. The nanoparticulate components in the cometary particle provide the first direct evidence from comets of reduced, carbon-rich regions that were present in the solar nebula.

  11. Effect of Cobalt Particle Size on Acetone Steam Reforming

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sun, Junming; Zhang, He; Yu, Ning

    2015-06-11

    Carbon-supported cobalt nanoparticles with different particle sizes were synthesized and characterized by complementary characterization techniques such as X-ray diffraction, N-2 sorption, acetone temperature-programmed desorption, transmission electron microscopy, and CO chemisorption. Using acetone steam reforming reaction as a probe reaction, we revealed a volcano-shape curve of the intrinsic activity (turnover frequency of acetone) and the CO2 selectivity as a function of the cobalt particle size with the highest activity and selectivity observed at a particle size of approximately 12.8nm. Our results indicate that the overall performance of acetone steam reforming is related to a combination of particle-size-dependent acetone decomposition, water dissociation,more » and the oxidation state of the cobalt nanoparticles.« less

  12. Black carbon absorption at the global scale is affected by particle-scale diversity in composition.

    PubMed

    Fierce, Laura; Bond, Tami C; Bauer, Susanne E; Mena, Francisco; Riemer, Nicole

    2016-09-01

    Atmospheric black carbon (BC) exerts a strong, but uncertain, warming effect on the climate. BC that is coated with non-absorbing material absorbs more strongly than the same amount of BC in an uncoated particle, but the magnitude of this absorption enhancement (Eabs) is not well constrained. Modelling studies and laboratory measurements have found stronger absorption enhancement than has been observed in the atmosphere. Here, using a particle-resolved aerosol model to simulate diverse BC populations, we show that absorption is overestimated by as much as a factor of two if diversity is neglected and population-averaged composition is assumed across all BC-containing particles. If, instead, composition diversity is resolved, we find Eabs=1-1.5 at low relative humidity, consistent with ambient observations. This study offers not only an explanation for the discrepancy between modelled and observed absorption enhancement, but also demonstrates how particle-scale simulations can be used to develop relationships for global-scale models.

  13. Black Carbon Absorption at the Global Scale Is Affected by Particle-Scale Diversity in Composition

    NASA Technical Reports Server (NTRS)

    Fierce, Laura; Bond, Tami C.; Bauer, Susanne E.; Mena, Francisco; Riemer, Nicole

    2016-01-01

    Atmospheric black carbon (BC) exerts a strong, but uncertain, warming effect on the climate. BC that is coated with non-absorbing material absorbs more strongly than the same amount of BC in an uncoated particle, but the magnitude of this absorption enhancement (E(sub abs)) is not well constrained. Modelling studies and laboratory measurements have found stronger absorption enhancement than has been observed in the atmosphere. Here, using a particle-resolved aerosol model to simulate diverse BC populations, we show that absorption is overestimated by as much as a factor of two if diversity is neglected and population-averaged composition is assumed across all BC-containing particles. If, instead, composition diversity is resolved, we find E(sub abs) = 1 - 1.5 at low relative humidity, consistent with ambient observations. This study offers not only an explanation for the discrepancy between modelled and observed absorption enhancement, but also demonstrates how particle-scale simulations can be used to develop relationships for global-scale models.

  14. Size distribution and mixing state of black carbon particles during a heavy air pollution episode in Shanghai

    NASA Astrophysics Data System (ADS)

    Gong, Xianda; Zhang, Ci; Chen, Hong; Nizkorodov, Sergey A.; Chen, Jianmin; Yang, Xin

    2016-04-01

    A Single Particle Aerosol Mass Spectrometer (SPAMS), a Single Particle Soot Photometer (SP2) and various meteorological instruments were employed to investigate the chemical and physical properties of black carbon (BC) aerosols during a regional air pollution episode in urban Shanghai over a 5-day period in December 2013. The refractory black carbon (rBC) mass concentrations measured by SP2 averaged 3.2 µg m-3, with the peak value of 12.1 µg m-3 at 04:26 LT on 7 December. The number of BC-containing particles captured by SPAMS in the size range 200-1200 nm agreed very well with that detected by SP2 (R2 = 0.87). A cluster analysis of the single particle mass spectra allowed for the separation of BC-containing particles into five major classes: (1) Pure BC; (2) BC attributed to biomass burning (BBBC); (3) K-rich BC-containing (KBC); (4) BC internally mixed with OC and ammonium sulfate (BCOC-SOx); (5) BC internally mixed with OC and ammonium nitrate (BCOC-NOx). The size distribution of internally mixed BC particles was bimodal. Detected by SP2, the condensation mode peaked around ˜ 230 nm and droplet mode peaked around ˜ 380 nm, with a clear valley in the size distribution around ˜ 320 nm. The condensation mode mainly consisted of traffic emissions, with particles featuring a small rBC core (˜ 60-80 nm) and a relatively thin absolute coating thickness (ACT, ˜ 50-130 nm). The droplet mode included highly aged traffic emission particles and biomass burning particles. The biomass burning particles had a larger rBC core (˜ 80-130 nm) and a thick ACT (˜ 110-300 nm). The highly aged traffic emissions had a smaller core (˜ 60-80 nm) and a very thick ACT (˜ 130-300 nm), which is larger than reported in any previous literature. A fast growth rate (˜ 20 nm h-1) of rBC with small core sizes was observed during the experiment. High concentrations pollutants like NO2 likely accelerated the aging process and resulted in a continuous size growth of r

  15. Agglomerates, smoke oxide particles, and carbon inclusions in condensed combustion products of an aluminized GAP-based propellant

    NASA Astrophysics Data System (ADS)

    Ao, Wen; Liu, Peijin; Yang, Wenjing

    2016-12-01

    In solid propellants, aluminum is widely used to improve the performance, however the condensed combustion products especially the large agglomerates generated from aluminum combustion significantly affect the combustion and internal flow inside the solid rocket motor. To clarify the properties of the condensed combustion products of aluminized propellants, a constant-pressure quench vessel was adopted to collect the combustion products. The morphology and chemical compositions of the collected products, were then studied by using scanning electron microscopy coupled with energy dispersive (SEM-EDS) method. Various structures have been observed in the condensed combustion products. Apart from the typical agglomerates or smoke oxide particles observed before, new structures including the smoke oxide clusters, irregular agglomerates and carbon-inclusions are discovered and investigated. Smoke oxide particles have the highest amount in the products. The highly dispersed oxide particle is spherical with very smooth surface and is on the order of 1-2 μm, but due to the high temperature and long residence time, these small particles will aggregate into smoke oxide clusters which are much larger than the initial particles. Three types of spherical agglomerates have been found. As the ambient gas temperature is much higher than the boiling point of Al2O3, the condensation layer inside which the aluminum drop is burning would evaporate quickly, which result in the fact that few "hollow agglomerates" has been found compared to "cap agglomerates" and "solid agglomerates". Irregular agglomerates usually larger than spherical agglomerates. The formation of irregular agglomerates likely happens by three stages: deformation of spherical aluminum drops; combination of particles with various shape; finally production of irregular agglomerates. EDS results show the ratio of O to Al on the surface of agglomerates is lower in comparison to smoke oxide particles. C and O account for

  16. Artificial neural network and particle swarm optimization for removal of methyl orange by gold nanoparticles loaded on activated carbon and Tamarisk.

    PubMed

    Ghaedi, M; Ghaedi, A M; Ansari, A; Mohammadi, F; Vafaei, A

    2014-11-11

    The influence of variables, namely initial dye concentration, adsorbent dosage (g), stirrer speed (rpm) and contact time (min) on the removal of methyl orange (MO) by gold nanoparticles loaded on activated carbon (Au-NP-AC) and Tamarisk were investigated using multiple linear regression (MLR) and artificial neural network (ANN) and the variables were optimized by partial swarm optimization (PSO). Comparison of the results achieved using proposed models, showed the ANN model was better than the MLR model for prediction of methyl orange removal using Au-NP-AC and Tamarisk. Using the optimal ANN model the coefficient of determination (R2) for the test data set were 0.958 and 0.989; mean squared error (MSE) values were 0.00082 and 0.0006 for Au-NP-AC and Tamarisk adsorbent, respectively. In this study a novel and green approach were reported for the synthesis of gold nanoparticle and activated carbon by Tamarisk. This material was characterized using different techniques such as SEM, TEM, XRD and BET. The usability of Au-NP-AC and activated carbon (AC) Tamarisk for the methyl orange from aqueous solutions was investigated. The effect of variables such as pH, initial dye concentration, adsorbent dosage (g) and contact time (min) on methyl orange removal were studied. Fitting the experimental equilibrium data to various isotherm models such as Langmuir, Freundlich, Tempkin and Dubinin-Radushkevich models show the suitability and applicability of the Langmuir model. Kinetic models such as pseudo-first order, pseudo-second order, Elovich and intraparticle diffusion models indicate that the second-order equation and intraparticle diffusion models control the kinetic of the adsorption process. The small amount of proposed Au-NP-AC and activated carbon (0.015 g and 0.75 g) is applicable for successful removal of methyl orange (>98%) in short time (20 min for Au-NP-AC and 45 min for Tamarisk-AC) with high adsorption capacity 161 mg g(-1) for Au-NP-AC and 3.84 mg g(-1) for

  17. Artificial neural network and particle swarm optimization for removal of methyl orange by gold nanoparticles loaded on activated carbon and Tamarisk

    NASA Astrophysics Data System (ADS)

    Ghaedi, M.; Ghaedi, A. M.; Ansari, A.; Mohammadi, F.; Vafaei, A.

    2014-11-01

    The influence of variables, namely initial dye concentration, adsorbent dosage (g), stirrer speed (rpm) and contact time (min) on the removal of methyl orange (MO) by gold nanoparticles loaded on activated carbon (Au-NP-AC) and Tamarisk were investigated using multiple linear regression (MLR) and artificial neural network (ANN) and the variables were optimized by partial swarm optimization (PSO). Comparison of the results achieved using proposed models, showed the ANN model was better than the MLR model for prediction of methyl orange removal using Au-NP-AC and Tamarisk. Using the optimal ANN model the coefficient of determination (R2) for the test data set were 0.958 and 0.989; mean squared error (MSE) values were 0.00082 and 0.0006 for Au-NP-AC and Tamarisk adsorbent, respectively. In this study a novel and green approach were reported for the synthesis of gold nanoparticle and activated carbon by Tamarisk. This material was characterized using different techniques such as SEM, TEM, XRD and BET. The usability of Au-NP-AC and activated carbon (AC) Tamarisk for the methyl orange from aqueous solutions was investigated. The effect of variables such as pH, initial dye concentration, adsorbent dosage (g) and contact time (min) on methyl orange removal were studied. Fitting the experimental equilibrium data to various isotherm models such as Langmuir, Freundlich, Tempkin and Dubinin-Radushkevich models show the suitability and applicability of the Langmuir model. Kinetic models such as pseudo-first order, pseudo-second order, Elovich and intraparticle diffusion models indicate that the second-order equation and intraparticle diffusion models control the kinetic of the adsorption process. The small amount of proposed Au-NP-AC and activated carbon (0.015 g and 0.75 g) is applicable for successful removal of methyl orange (>98%) in short time (20 min for Au-NP-AC and 45 min for Tamarisk-AC) with high adsorption capacity 161 mg g-1 for Au-NP-AC and 3.84 mg g-1 for Tamarisk-AC.

  18. Gold nano-particle formation from crystalline AuCN: Comparison of thermal, plasma- and ion-beam activated decomposition

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Beck, Mihály T.; Bertóti, Imre, E-mail: bertoti.imre@ttk.mta.hu; Mohai, Miklós

    In this work, in addition to the conventional thermal process, two non-conventional ways, the plasma and ion beam activations are described for preparing gold nanoparticles from microcrystalline AuCN precursor. The phase formation at plasma and ion beam treatments was compared with that at thermal treatments and the products and transformations were characterized by thermogravimetry-mass-spectrometry (TG-MS), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). TG-MS measurements in Ar atmosphere revealed that AuCN decomposition starts at 400 °C and completes at ≈700 °C with evolution of gaseous (CN){sub 2}. XPS and TEM show that in heat treatment at 450 °C formore » 1 h in Ar, loss of nitrogen and carbon occurs and small, 5–30 nm gold particles forms. Heating at 450 °C for 10 h in sealed ampoule, much larger, 60–200 nm size and well faceted Au particles develop together with a fibrous (CN){sub n} polymer phase, and the Au crystallites are covered by a 3–5 nm thick polymer shell. Low pressure Ar plasma treatment at 300 eV energy results in 4–20 nm size Au particles and removes most of the nitrogen and part of carbon. During Ar{sup +} ion bombardment with 2500 eV energy, 5–30 nm size Au crystallites form already in 10 min, with preferential loss of nitrogen and with increased amount of carbon residue. The results suggest that plasma and ion beam activation, acting similarly to thermal treatment, may be used to prepare Au nanoparticles from AuCN on selected surface areas either by depositing AuCN precursors on selected regions or by focusing the applied ionized radiation. Thus they may offer alternative ways for preparing tailor-made catalysts, electronic devices and sensors for different applications. - Graphical abstract: Proposed scheme of the decomposition mechanism of AuCN samples: heat treatment in Ar flow (a) and in sealed ampoule (b); Ar{sup +} ion treatment at 300 eV (c) and at 2500 eV (d). Cross section

  19. Modification of the N-Terminus of a Calcium Carbonate Precipitating Peptide Affects Calcium Carbonate Mineralization.

    PubMed

    Usui, Kenji; Yokota, Shin-Ichiro; Ozaki, Makoto; Sakashita, Shungo; Imai, Takahito; Tomizaki, Kin-Ya

    2018-01-01

    A core sequence (the 9 C-terminal residues) of calcification-associated peptide (CAP- 1) isolated from the exoskeleton of the red swamp crayfish was previously shown to control calcium carbonate precipitation with chitin. In addition, a modified core sequence in which the phosphorylated serine at the N terminus is replaced with serine exhibits was also previously shown to alter precipitation characteristics with chitin. We focused on calcium carbonate precipitation and attempted to elucidate aspects of the mechanism underlying mineralization. We attempted to evaluate in detail the effects of modifying the N-terminus in the core sequence on calcium carbonate mineralization without chitin. The peptide modifications included phosphorylation, dephosphorylation, and a free or acetylated Nterminus. The peptides were synthesized manually on Wang resin using the DIPCI-DMAP method for the first residue, and Fmoc solid phase peptide synthesis with HBTU-HOBt for the subsequent residues. Prior to calcium carbonate precipitation, calcium carbonate was suspended in MilliQ water. Carbon dioxide gas was bubbled into the stirred suspension, then the remaining solid CaCO3 was removed by filtration. The concentration of calcium ions in the solution was determined by standard titration with ethylenediaminetetraacetate. Calcium carbonate precipitation was conducted in a micro tube for 3 h at 37°C. We used the micro-scale techniques AFM (atomic force microscopy) and TEM (transmission electron microscopy), and the macro-scale techniques chelate titration, HPLC, gel filtration, CD (circular dichroism) and DLS (dynamic light scattering). We determined the morphologies of the calcium carbonate deposits using AFM and TEM. The pS peptide provided the best control of the shape and size of the calcium carbonate round particles. The acetylated peptides (Ac-S and Ac-pS) provided bigger particles with various shapes. S peptide provided a mixture of bigger particles and amorphous particles. We

  20. Particle Acceleration in Active Galactic Nuclei

    NASA Technical Reports Server (NTRS)

    Miller, James A.

    1997-01-01

    The high efficiency of energy generation inferred from radio observations of quasars and X-ray observations of Seyfert active galactic nuclei (AGNs) is apparently achieved only by the gravitational conversion of the rest mass energy of accreting matter onto supermassive black holes. Evidence for the acceleration of particles to high energies by a central engine is also inferred from observations of apparent superluminal motion in flat spectrum, core-dominated radio sources. This phenomenon is widely attributed to the ejection of relativistic bulk plasma from the nuclei of active galaxies, and accounts for the existence of large scale radio jets and lobes at large distances from the central regions of radio galaxies. Reports of radio jets and superluminal motion from galactic black hole candidate X-ray sources indicate that similar processes are operating in these sources. Observations of luminous, rapidly variable high-energy radiation from active galactic nuclei (AGNs) with the Compton Gamma Ray Observatory show directly that particles are accelerated to high energies in a compact environment. The mechanisms which transform the gravitational potential energy of the infalling matter into nonthermal particle energy in galactic black hole candidates and AGNs are not conclusively identified, although several have been proposed. These include direct acceleration by static electric fields (resulting from, for example, magnetic reconnection), shock acceleration, and energy extraction from the rotational energy of Kerr black holes. The dominant acceleration mechanism(s) operating in the black hole environment can only be determined, of course, by a comparison of model predictions with observations. The purpose of the work proposed for this grant was to investigate stochastic particle acceleration through resonant interactions with plasma waves that populate the magnetosphere surrounding an accreting black hole. Stochastic acceleration has been successfully applied to the

  1. Elasticity-induced force reversal between active spinning particles in dense passive media

    PubMed Central

    Aragones, J. L.; Steimel, J. P.; Alexander-Katz, A.

    2016-01-01

    The self-organization of active particles is governed by their dynamic effective interactions. Such interactions are controlled by the medium in which such active agents reside. Here we study the interactions between active agents in a dense non-active medium. Our system consists of actuated, spinning, active particles embedded in a dense monolayer of passive, or non-active, particles. We demonstrate that the presence of the passive monolayer alters markedly the properties of the system and results in a reversal of the forces between active spinning particles from repulsive to attractive. The origin of such reversal is due to the coupling between the active stresses and elasticity of the system. This discovery provides a mechanism for the interaction between active agents in complex and structured media, opening up opportunities to tune the interaction range and directionality via the mechanical properties of the medium. PMID:27112961

  2. Reactive adsorption of SO2 on activated carbons with deposited iron nanoparticles.

    PubMed

    Arcibar-Orozco, Javier A; Rangel-Mendez, J Rene; Bandosz, Teresa J

    2013-02-15

    The effect of iron particle size anchored on the surface of commercial activated carbon on the removal of SO(2) from a gas phase was studied. Nanosize iron particles were deposited using forced hydrolysis of FeCl(3) with or without H(3)PO(4) as a capping agent. Dynamic adsorption experiments were carried out on either dry or pre-humidified materials and the adsorption capacities were calculated. The surface of the initial and exhausted materials was extensively characterized by microscopic, porosity, thermogravimetric and surface chemistry. The results indicate that the SO(2) adsorption capacity increased two and half times after the prehumidification process owing to the formation of H(2)SO(4) in the porous system. Iron species enhance the SO(2) adsorption capacity only when very small nanoparticles are deposited on the pore walls as a thin layer. Large iron nanoparticles block the ultramicropores decreasing the accessibility of the active sites and consuming oxygen that rest adsorption centers for SO(2) molecules. Iron nanoparticles of about 3-4 nm provide highly dispersed adsorption sites for SO(2) molecules and thus increase the adsorption capacity of about 80%. Fe(2)(SO(4))(3) was detected on the surface of exhausted samples. Copyright © 2012 Elsevier B.V. All rights reserved.

  3. Charged particle detectors with active detector surface for partial energy deposition of the charged particles and related methods

    DOEpatents

    Gerts, David W; Bean, Robert S; Metcalf, Richard R

    2013-02-19

    A radiation detector is disclosed. The radiation detector comprises an active detector surface configured to generate charge carriers in response to charged particles associated with incident radiation. The active detector surface is further configured with a sufficient thickness for a partial energy deposition of the charged particles to occur and permit the charged particles to pass through the active detector surface. The radiation detector further comprises a plurality of voltage leads coupled to the active detector surface. The plurality of voltage leads is configured to couple to a voltage source to generate a voltage drop across the active detector surface and to separate the charge carriers into a plurality of electrons and holes for detection. The active detector surface may comprise one or more graphene layers. Timing data between active detector surfaces may be used to determine energy of the incident radiation. Other apparatuses and methods are disclosed herein.

  4. Brownian aggregation rate of colloid particles with several active sites

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Nekrasov, Vyacheslav M.; Yurkin, Maxim A.; Chernyshev, Andrei V., E-mail: chern@ns.kinetics.nsc.ru

    2014-08-14

    We theoretically analyze the aggregation kinetics of colloid particles with several active sites. Such particles (so-called “patchy particles”) are well known as chemically anisotropic reactants, but the corresponding rate constant of their aggregation has not yet been established in a convenient analytical form. Using kinematic approximation for the diffusion problem, we derived an analytical formula for the diffusion-controlled reaction rate constant between two colloid particles (or clusters) with several small active sites under the following assumptions: the relative translational motion is Brownian diffusion, and the isotropic stochastic reorientation of each particle is Markovian and arbitrarily correlated. This formula was shownmore » to produce accurate results in comparison with more sophisticated approaches. Also, to account for the case of a low number of active sites per particle we used Monte Carlo stochastic algorithm based on Gillespie method. Simulations showed that such discrete model is required when this number is less than 10. Finally, we applied the developed approach to the simulation of immunoagglutination, assuming that the formed clusters have fractal structure.« less

  5. Transport of underdamped self-propelled particles in active density waves

    NASA Astrophysics Data System (ADS)

    Zhu, Wei-jing; Huang, Xiao-qun; Ai, Bao-quan

    2018-03-01

    Transport of underdamped self-propelled particles is numerically investigated in active density waves. From numerical simulations, it is found that the inertia can strongly affect the transport of self-propelled particles. By changing the wave speed or the friction coefficient, the average velocity can change its direction. The direction of the transport is also determined by the competition between the inertia effect and the traveling waves. Therefore, underdamped active particles can move in different directions and can be separated by suitably tailoring the parameters.

  6. Activated carbon fibers and engineered forms from renewable resources

    DOEpatents

    Baker, Frederick S

    2013-02-19

    A method of producing activated carbon fibers (ACFs) includes the steps of providing a natural carbonaceous precursor fiber material, blending the carbonaceous precursor material with a chemical activation agent to form chemical agent-impregnated precursor fibers, spinning the chemical agent-impregnated precursor material into fibers, and thermally treating the chemical agent-impregnated precursor fibers. The carbonaceous precursor material is both carbonized and activated to form ACFs in a single step. The method produces ACFs exclusive of a step to isolate an intermediate carbon fiber.

  7. Activated carbon fibers and engineered forms from renewable resources

    DOEpatents

    Baker, Frederick S.

    2010-06-01

    A method of producing activated carbon fibers (ACFs) includes the steps of providing a natural carbonaceous precursor fiber material, blending the carbonaceous precursor material with a chemical activation agent to form chemical agent-impregnated precursor fibers, spinning the chemical agent-impregnated precursor material into fibers, and thermally treating the chemical agent-impregnated precursor fibers. The carbonaceous precursor material is both carbonized and activated to form ACFs in a single step. The method produces ACFs exclusive of a step to isolate an intermediate carbon fiber.

  8. [Comparison study on adsorption of middle molecular substances with multiwalled carbon nanotubes and activated carbon].

    PubMed

    Li, Guifeng; Wan, Jianxin; Huang, Xiangqian; Zeng, Qiao; Tang, Jing

    2011-08-01

    In recent years, multi-walled carbon nanotubes (MWCTs) are very favorable to the adsorption of middle molecular substances in the hemoperfusion because of their multiporous structure, large surface area and high reactivity, which are beneficial to the excellent absorption properties. The purpose of this study was to study the MWCTs on the adsorption capacity of the middle molecular substances. Vitamin B12 (VB12) was selected as a model of the middle molecular substances. The morphologies of MWCTs and activated carbon from commercial "carbon kidney" were observed with scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The adsorption behavior of VB12 was compared to each other with UV-visible absorption spectra. The MWCTs formed a sophistaicate gap structure, and compared to the activated carbon, MWCTs had a larger surface area. By Langmuir equation and Freundlich equation fitting analysis, VB12 adsorption on MWCTs is fit for multi-molecular layer adsorption, and the adsorption type of activated carbon is more inclined to the model corresponding to Langmuir monolayer adsorption. The adsorption rate of MWCTs is faster than that of the activated carbon and the adsorption capacity is greater, which could be expected to become the new adsorbent in the hemoperfusion.

  9. Nitrogen-Containing Carbon Nanotube Synthesized from Polymelem and Activated Carbon Derived from Polymer Blend

    NASA Astrophysics Data System (ADS)

    Qin, Nan

    Polymelem possesses a polymeric structure of heptazine (C6N 7) rings connected by amine bridges and our study has demonstrated that it is a promising precursor for the synthesis of nitrogen-containing carbon materials. Nitrogen-containing carbon nanotube (NCNT) was produced by pyrolyzing polymelem as a dual source of carbon and nitrogen with Raney nickel in a high pressure stainless steel cell. Activated carbon was produced from poly(ether ether ketone)/poly(ether imide) (PEEK/PEI blend) and incorporated with polymelem to enhance the hydrogen adsorption. Polymelem was successfully synthesized by pyrolyzing melamine at 450--650 °C and its structure was elucidated by 13C solid state NMR, FTIR, and XRD. The molecular weight determined by a novel LDI MS equipped with a LIFT mode illuminated that polymelem has both linear and cyclic connectivity with a degree of polymerization of 2--5 depending on the synthesis temperature. The decomposition products of polymelem were determined to be cyanoamide, dicyanoamide, and tricyanoamine. Tricyanoamine is the smallest carbon nitride molecule and has been experimentally confirmed for the first time in this study. When polymelem was decomposed in the presence of Raney nickel, homogenous NCNT with nitrogen content of ˜ 4--19 atom% was produced. A mechanism based on a detail analysis of the TEM images at different growth stages proposed that the NCNT propagated via a tip-growth mechanism originating at the nano-domains within the Raney nickel, and was accompanied with the aggregation of the nickel catalysts. Such NCNT exhibited a cup-stack wall structure paired with a compartmental feature. The nitrogen content, tube diameter and wall thickness greatly depended on synthesis conditions. The activated carbon derived from PEEK/PEI blend demonstrated a surface area up to ˜3000 m2/g, and average pore size of < 20 A. Such activated carbon exhibited a hydrogen storage capacity of up to 6.47 wt% at 40 bar, 77 K. The activated carbon has

  10. Isotopic composition of high-activity particles released in the Chernobyl accident.

    PubMed

    Osuch, S; Dabrowska, M; Jaracz, P; Kaczanowski, J; Le Van Khoi; Mirowski, S; Piasecki, E; Szeflińska, G; Szefliński, Z; Tropiło, J

    1989-11-01

    Gamma spectra were measured and activities of the detected isotopes were analyzed for 206 high-activity particles (hot particles, HPs) found in northeastern Poland after the Chernobyl accident. The isotopic composition of HPs observed in gamma-activity is compared with that of the general fallout and core inventory calculations. Particle formation and a process of depletion in Ru and Cs isotopes are discussed. On the basis of a search performed a year later, some comments on the behavior of HPs in the soil are made.

  11. Methods for forming particles from single source precursors

    DOEpatents

    Fox, Robert V [Idaho Falls, ID; Rodriguez, Rene G [Pocatello, ID; Pak, Joshua [Pocatello, ID

    2011-08-23

    Single source precursors are subjected to carbon dioxide to form particles of material. The carbon dioxide may be in a supercritical state. Single source precursors also may be subjected to supercritical fluids other than supercritical carbon dioxide to form particles of material. The methods may be used to form nanoparticles. In some embodiments, the methods are used to form chalcopyrite materials. Devices such as, for example, semiconductor devices may be fabricated that include such particles. Methods of forming semiconductor devices include subjecting single source precursors to carbon dioxide to form particles of semiconductor material, and establishing electrical contact between the particles and an electrode.

  12. Hydrodynamic interaction of a self-propelling particle with a wall : Comparison between an active Janus particle and a squirmer model.

    PubMed

    Shen, Zaiyi; Würger, Alois; Lintuvuori, Juho S

    2018-03-27

    Using lattice Boltzmann simulations we study the hydrodynamics of an active spherical particle near a no-slip wall. We develop a computational model for an active Janus particle, by considering different and independent mobilities on the two hemispheres and compare the behaviour to a standard squirmer model. We show that the topology of the far-field hydrodynamic nature of the active Janus particle is similar to the standard squirmer model, but in the near-field the hydrodynamics differ. In order to study how the near-field effects affect the interaction between the particle and a flat wall, we compare the behaviour of a Janus swimmer and a squirmer near a no-slip surface via extensive numerical simulations. Our results show generally a good agreement between these two models, but they reveal some key differences especially with low magnitudes of the squirming parameter [Formula: see text]. Notably the affinity of the particles to be trapped at a surface is increased for the active Janus particles when compared to standard squirmers. Finally, we find that when the particle is trapped on the surface, the velocity parallel to the surface exceeds the bulk swimming speed and scales linearly with [Formula: see text].

  13. Red mud carbonation using carbon dioxide: Effects of carbonate and calcium ions on goethite surface properties and settling.

    PubMed

    Liang, Gaojie; Chen, Wenmi; Nguyen, Anh V; Nguyen, Tuan A H

    2018-05-01

    Carbonation using CO 2 appears as an attractive solution for disposing of red mud suspensions, an aluminum industry hazardous waste since it also offers an option for CO 2 sequestration. Here we report the novel findings that CO 3 2- together with Ca 2+ can significantly affect the surface properties and settling of goethite, a major component of red mud. Specifically, their effects on the goethite surface chemistry, colloidal interaction forces and settling in alkaline solutions are investigated. The surface potential becomes more negative by the formation of carbonate inner-sphere complexes on goethite surface. It is consistent with the strong repulsion, decreased particle size and settling velocity with increased carbonate concentrations as measured by atomic force microscopy, particle size analysis, and particle settling. Adding Ca 2+ that forms outer-sphere complexes with pre-adsorbed carbonate changes goethite surface charge negligibly. Changing repulsion to the attraction between goethite surfaces by increasing calcium dosage indicates the surface bridging, in accordance with the increased settling velocity. The adverse effect of carbonate on goethite flocculation is probably due to its specific chemisorption and competition with flocculants. By forming outer-sphere complexes together with the flocculant-calcium bridging effect, calcium ions can eliminate the negative influence of carbonate and improve the flocculation of goethite particles. These findings contribute to a better understanding of goethite particle interaction with salt ions and flocculants in controlling the particle behavior in the handling processes, including the red mud carbonation. Copyright © 2018 Elsevier Inc. All rights reserved.

  14. High Selectivity Toward C2H4 Production over Cu Particles Supported by Butterfly-Wing-Derived Carbon Frameworks.

    PubMed

    Huo, Yajiao; Peng, Xianyun; Liu, Xijun; Li, Huaiyu; Luo, Jun

    2018-04-18

    Converting carbon dioxide to useful C2 chemicals in a selective and efficient manner remains a major challenge in renewable and sustainable energy research. Herein, we adopt butterfly wings to assist the preparation of an electrocatalyst containing monodispersed Cu particles supported by nitrogen-doped carbon frameworks for an efficient reduction of CO 2 . Benefiting from structure advantages and the synergistic effect between nitrogen dopants and stepped surface-rich Cu particles, the resulting catalyst exhibited a high faradic efficiency of 63.7 ± 1.4% for ethylene production (corresponding to an ethylene/methane products' ratio of 57.9 ± 5.4) and an excellent durability (∼100% retention after 24 h). This work presents some guidelines for the rational design and accurate modulation of metal heterocatalysts for high selectivity toward ethylene from CO 2 electroreduction.

  15. Fenton-Driven Regeneration of MTBE-spent Granular Activated Carbon

    EPA Science Inventory

    Fenton-driven regeneration of Methyl tert-butyl ether (MTBE)-spent granular activated carbon (GAC) involves the combined, synergistic use of two treatment technologies: adsorption of organic chemicals onto activated carbon and Fenton-driven oxidation regeneration of the spent-GAC...

  16. Photoconductivity of Activated Carbon Fibers

    DOE R&D Accomplishments Database

    Kuriyama, K.; Dresselhaus, M. S.

    1990-08-01

    The photoconductivity is measured on a high-surface-area disordered carbon material, namely activated carbon fibers, to investigate their electronic properties. Measurements of decay time, recombination kinetics and temperature dependence of the photoconductivity generally reflect the electronic properties of a material. The material studied in this paper is a highly disordered carbon derived from a phenolic precursor, having a huge specific surface area of 1000--2000m{sup 2}/g. Our preliminary thermopower measurements suggest that this carbon material is a p-type semiconductor with an amorphous-like microstructure. The intrinsic electrical conductivity, on the order of 20S/cm at room temperature, increases with increasing temperature in the range 30--290K. In contrast with the intrinsic conductivity, the photoconductivity in vacuum decreases with increasing temperature. The recombination kinetics changes from a monomolecular process at room temperature to a biomolecular process at low temperatures. The observed decay time of the photoconductivity is {approx equal}0.3sec. The magnitude of the photoconductive signal was reduced by a factor of ten when the sample was exposed to air. The intrinsic carrier density and the activation energy for conduction are estimated to be {approx equal}10{sup 21}/cm{sup 3} and {approx equal}20meV, respectively. The majority of the induced photocarriers and of the intrinsic carriers are trapped, resulting in the long decay time of the photoconductivity and the positive temperature dependence of the conductivity.

  17. Carbon Raman Spectroscopy of 36 Inter-Planetary Dust Particles

    NASA Technical Reports Server (NTRS)

    Busemann, H.; Nittler, L. R.; Davidson, J.; Franchi, I. A.; Messenger, S.; Nakamura-Messenger, K.; Palma, R. L.; Pepin, R. O.

    2009-01-01

    Carbon Raman spectroscopy is a useful tool to determine the degree of order of organic material (OM) in extra-terrestrial matter. As shown for meteoritic OM [e.g., 2], peak parameters of D and G bands are a measure of thermal alteration, causing graphitization (order), and amorphization, e.g. during protoplanetary irradiation, causing disorder. Th e most pristine interplanetary dust particles (IDPs) may come from comets. However, their exact provenance is unknown. IDP collection during Earth?s passage through comet Grigg-Skjellerup?s dust stream ("GSC" collectors) may increase the probability of collecting fresh IDPs from a known, cometary source. We used Raman spectroscopy to compare 21 GSC-IDPs with 15 IDPs collected at different periods, and found that the variation among GSC-IDPs is larger than among non-GSC IDPs, with the most primitive IDPs being mostly GSC-IDPs.

  18. Personal measurement of exposure to black carbon and ultrafine particles in schoolchildren from PARIS cohort (Paris, France).

    PubMed

    Paunescu, A-C; Attoui, M; Bouallala, S; Sunyer, J; Momas, I

    2017-07-01

    This study aimed to measure in French children personal exposure concentrations of black carbon (BC) and ultrafine particles (UFP) and to quantify the contribution of different microenvironments (home, school, places of extracurricular activities, transport) to their total exposure. It was conducted on 96 9-year-old children from the PARIS birth cohort. BC and UFP were continuously measured by portable devices (microAeth ® AE51 and DiSCmini ® ) for a minimum of 24 hours, while participating families simultaneously filled in a space-time-activities-budget questionnaire. BC exposure concentration was higher during trips (principally metro/train and bus), while UFP exposure concentration was higher during indoor activities (mainly eating at restaurants) and in trips. The most important UFP peaks were measured at home, especially during cooking. Home and school together accounted for much of the total exposure, 83.8% for BC and 85.3% for UFP. The contribution of transport to total exposure was 12.4% for BC and 9.7% for UFP, while extracurricular activities were responsible for 3.8% and 5% of the total exposure to BC and UFP, respectively. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  19. Brown carbon and internal mixing in biomass burning particles

    PubMed Central

    Lack, Daniel A.; Langridge, Justin M.; Bahreini, Roya; Cappa, Christopher D.; Middlebrook, Ann M.; Schwarz, Joshua P.

    2012-01-01

    Biomass burning (BB) contributes large amounts of black carbon (BC) and particulate organic matter (POM) to the atmosphere and contributes significantly to the earth’s radiation balance. BB particles can be a complicated optical system, with scattering and absorption contributions from BC, internal mixtures of BC and POM, and wavelength-dependent absorption of POM. Large amounts of POM can also be externally mixed. We report on the unique ability of multi-wavelength photo-acoustic measurements of dry and thermal-denuded absorption to deconstruct this complicated wavelength-dependent system of absorption and mixing. Optical measurements of BB particles from the Four Mile Canyon fire near Boulder, Colorado, showed that internal mixtures of BC and POM enhanced absorption by up to 70%. The data supports the assumption that the POM was very weakly absorbing at 532 nm. Enhanced absorption at 404 nm was in excess of 200% above BC absorption and varied as POM mass changed, indicative of absorbing POM. Absorption by internal mixing of BC and POM contributed 19( ± 8)% to total 404-nm absorption, while BC alone contributed 54( ± 16)%. Approximately 83% of POM mass was externally mixed, the absorption of which contributed 27( ± 15)% to total particle absorption (at 404 nm). The imaginary refractive index and mass absorption efficiency (MAE) of POM at 404 nm changed throughout the sampling period and were found to be 0.007 ± 0.005 and 0.82 ± 0.43 m2 g-1, respectively. Our analysis shows that the MAE of POM can be biased high by up to 50% if absorption from internal mixing of POM and BC is not included. PMID:22927381

  20. Brown carbon and internal mixing in biomass burning particles.

    PubMed

    Lack, Daniel A; Langridge, Justin M; Bahreini, Roya; Cappa, Christopher D; Middlebrook, Ann M; Schwarz, Joshua P

    2012-09-11

    Biomass burning (BB) contributes large amounts of black carbon (BC) and particulate organic matter (POM) to the atmosphere and contributes significantly to the earth's radiation balance. BB particles can be a complicated optical system, with scattering and absorption contributions from BC, internal mixtures of BC and POM, and wavelength-dependent absorption of POM. Large amounts of POM can also be externally mixed. We report on the unique ability of multi-wavelength photo-acoustic measurements of dry and thermal-denuded absorption to deconstruct this complicated wavelength-dependent system of absorption and mixing. Optical measurements of BB particles from the Four Mile Canyon fire near Boulder, Colorado, showed that internal mixtures of BC and POM enhanced absorption by up to 70%. The data supports the assumption that the POM was very weakly absorbing at 532 nm. Enhanced absorption at 404 nm was in excess of 200% above BC absorption and varied as POM mass changed, indicative of absorbing POM. Absorption by internal mixing of BC and POM contributed 19( ± 8)% to total 404-nm absorption, while BC alone contributed 54( ± 16)%. Approximately 83% of POM mass was externally mixed, the absorption of which contributed 27( ± 15)% to total particle absorption (at 404 nm). The imaginary refractive index and mass absorption efficiency (MAE) of POM at 404 nm changed throughout the sampling period and were found to be 0.007 ± 0.005 and 0.82 ± 0.43 m(2) g(-1), respectively. Our analysis shows that the MAE of POM can be biased high by up to 50% if absorption from internal mixing of POM and BC is not included.

  1. [Adsorption kinetics and mechanism of lead (II) on polyamine-functionalized mesoporous activated carbon].

    PubMed

    Li, Kun-Quan; Wang, Yan-Jin; Yang, Mei-Rong; Zhu, Zhi-Qiang; Zheng, Zheng

    2014-08-01

    Bagasse mesoporous carbon was prepared by microwave assisted H3 PO4 activation. Amido and imido groups were modified with ethanediamine on the channels' surface of mesoporous carbon through nitric oxidation and amide reaction. The influence of Pb(II) concentration, adsorption time on Pb(II) adsorption on the ethanediamine-modified mesoporous carbon (AC-EDA) was investigated. The adsorption kinetics and mechanism were also discussed. The results showed that AC-EDA had a great performance for Pb(II) adsorption, and more than 70% of Pb(II) was adsorbed in 5 minutes. The adsorption amount of Pb(II) on the carbon increased with the increase of solution pH in acidic conditions. It was found that AC-EDA had different binding energies on different adsorption sites for Pb(II) separation. The Pb(II) adsorption process on AC-EDA was controlled by intra-particle diffusion in the first 3 min, and then film diffusion played the important pole on the adsorption. The adsorption amount increased with the increase of temperature, indicating the adsorption was an endothermic reaction. The high adsorption energy (> 11 kJ x mol(-1)) implied that the) adsorption was a chemical adsorption. The XPS of AC-EDA before and after Pb(II) adsorption showed that the polyamine group was involved in the adsorption, and should be a main factor of the high efficient adsorption.

  2. Polarized excitons and optical activity in single-wall carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Chang, Yao-Wen; Jin, Bih-Yaw

    2018-05-01

    The polarized excitons and optical activity of single-wall carbon nanotubes (SWNTs) are studied theoretically by π -electron Hamiltonian and helical-rotational symmetry. By taking advantage of the symmetrization, the single-particle energy and properties of a SWNT are characterized with the corresponding helical band structure. The dipole-moment matrix elements, magnetic-moment matrix elements, and the selection rules can also be derived. Based on different selection rules, the optical transitions can be assigned as the parallel-polarized, left-handed circularly-polarized, and right-handed circularly-polarized transitions, where the combination of the last two gives the cross-polarized transition. The absorption and circular dichroism (CD) spectra are simulated by exciton calculation. The calculated results are well comparable with the reported measurements. Built on the foundation, magnetic-field effects on the polarized excitons and optical activity of SWNTs are studied. Dark-bright exciton splitting and interband Faraday effect in the CD spectrum of SWNTs under an axial magnetic field are predicted. The Faraday rotation dispersion can be analyzed according to the selection rules of circular polarizations and the helical band structure.

  3. Hierarchically structured activated carbon for ultracapacitors

    NASA Astrophysics Data System (ADS)

    Kim, Mok-Hwa; Kim, Kwang-Bum; Park, Sun-Min; Roh, Kwang Chul

    2016-02-01

    To resolve the pore-associated bottleneck problem observed in the electrode materials used for ultracapacitors, which inhibits the transport of the electrolyte ions, we designed hierarchically structured activated carbon (HAC) by synthesizing a mesoporous silica template/carbon composite and chemically activating it to simultaneously remove the silica template and increase the pore volume. The resulting HAC had a well-designed, unique porous structure, which allowed for large interfaces for efficient electric double-layer formation. Given the unique characteristics of the HAC, we believe that the developed synthesis strategy provides important insights into the design and fabrication of hierarchical carbon nanostructures. The HAC, which had a specific surface area of 1,957 m2 g-1, exhibited an extremely high specific capacitance of 157 F g-1 (95 F cc-1), as well as a high rate capability. This indicated that it had superior energy storage capability and was thus suitable for use in advanced ultracapacitors.

  4. Clay Chemistry's Influence on the Average Carbon Content and Particle Size at the Ninety-Six Historical Site, South Carolina

    NASA Astrophysics Data System (ADS)

    Lintz, L.; Werts, S. P.

    2014-12-01

    The Ninety-Six National Historic Site is located in Greenwood County, SC. Recent geologic mapping of this area has revealed differences in soil properties over short distances within the park. We studied the chemistry of the clay minerals found within the soils to see if there was a correlation between the amounts of soil organic carbon contained in the soil and particle size in individual soil horizons. Three different vegetation areas, including an old field, a deciduous forest, and a pine forest were selected to see what influence vegetation type had on the clay chemistry and carbon levels as well. Four samples containing the O, A, and B horizons were taken from each location and we studied the carbon and nitrogen content using an elemental analyzer, particle size using a Laser Diffraction Particle Size Analyzer, and clay mineralogy with powder X-ray diffraction of each soil sample. Samples from the old field and pine forest gave an overall negative correlation between carbon content and clay percentage, which is against the normal trend for Southern Piedmont Ultisols. The deciduous forest samples gave no correlation at all between its carbon content and clay percentage. Together, all three locations show the same negative relationship, while once separated into vegetation type and A and B horizons it shows even more abnormal relationships of negative while several show no correlation (R2= 0.007403- 0.56268). Using powder XRD, we ran clay samples from each A and B horizon for the clay mineralogy. All three vegetation areas had the same results of containing quartz, kaolinite, and Fe oxides, therefore, clay chemistry is not a reason behind the abnormal trend of a negative correlation between average carbon content and clay percentage. Considering that all three locations have the same climate, topography, and parent material of metagranite, it could be reasonable to assume these results are a factor of environmental and biological influences rather than clay type.

  5. Preparation of hollow mesoporous carbon spheres and their performances for electrochemical applications

    NASA Astrophysics Data System (ADS)

    Ariyanto, T.; Zhang, G. R.; Kern, A.; Etzold, B. J. M.

    2018-03-01

    Hollow carbon materials have received intensive attention for energy storage/conversion applications due to their attractive properties of high conductivity, high surface area, large void and short diffusion pathway. In this work, a novel hollow mesoporous material based on carbide-derived carbon (CDC) is presented. CDC is a new class of carbon material synthesized by the selective extraction of metals from metal carbides. With a two-stage extraction procedure of carbides with chlorine, firstly hybrid core-shell carbon particles were synthesized, i.e. mesoporous/graphitic carbon shells covering microporous/amorphous carbon cores. The amorphous cores were then selectively removed from particles by a careful oxidative treatment utilizing its low thermal characters while the more stable carbon shells remained, thus resulting hollow particles. The characterization methods (e.g. N2 sorption, Raman spectroscopy, temperature-programmed oxidation and SEM) proved the successful synthesis of the aspired material. In electric double-layer capacitor (EDLC) testing, this novel hollow core material showed a remarkable enhancement of EDLC’s rate handling ability (75% at a high scan rate) with respect to an entirely solid-mesoporous material. Furthermore, as a fuel cell catalyst support the material showed higher Pt mass activity (a factor of 1.8) compared to a conventional carbon support for methanol oxidation without noticeably decreasing activity in a long-term testing. Therefore, this carbon nanostructure shows great promises as efficient electrode materials for energy storage and conversion systems.

  6. Preparation of activated carbon from cherry stones by chemical activation with ZnCl 2

    NASA Astrophysics Data System (ADS)

    Olivares-Marín, M.; Fernández-González, C.; Macías-García, A.; Gómez-Serrano, V.

    2006-06-01

    Cherry stones (CS), an industrial product generated abundantly in the Valle del Jerte (Cáceres province, Spain), were used as precursor in the preparation of activated carbon by chemical activation with ZnCl 2. The influence of process variables such as the carbonisation temperature and the ZnCl 2:CS ratio (impregnation ratio) on textural and chemical-surface properties of the products obtained was studied. Such products were characterised texturally by adsorption of N 2 at -196 °C, mercury porosimetry and density measurements. Information on the surface functional groups and structures of the carbons was provided by FT-IR spectroscopy. Activated carbon with a high development of surface area and porosity is prepared. When using the 4:1 impregnation ratio, the specific surface area (BET) of the resultant carbon is as high as 1971 m 2 g -1. The effect of the increase in the impregnation ratio on the porous structure of activated carbon is stronger than that of the rise in the carbonisation temperature, whereas the opposite applies to the effect on the surface functional groups and structures.

  7. Ammonia modification of activated carbon to enhance carbon dioxide adsorption: Effect of pre-oxidation

    NASA Astrophysics Data System (ADS)

    Shafeeyan, Mohammad Saleh; Daud, Wan Mohd Ashri Wan; Houshmand, Amirhossein; Arami-Niya, Arash

    2011-02-01

    A commercial granular activated carbon (GAC) was subjected to thermal treatment with ammonia for obtaining an efficient carbon dioxide (CO2) adsorbent. In general, CO2 adsorption capacity of activated carbon can be increased by introduction of basic nitrogen functionalities onto the carbon surface. In this work, the effect of oxygen surface groups before introduction of basic nitrogen functionalities to the carbon surface on CO2 adsorption capacity was investigated. For this purpose two different approaches of ammonia treatment without preliminary oxidation and amination of oxidized samples were studied. Modified carbons were characterized by elemental analysis and Fourier Transform Infrared spectroscopy (FT-IR) to study the impact of changes in surface chemistry and formation of specific surface groups on adsorption properties. The texture of the samples was characterized by conducting N2 adsorption/desorption at -196 °C. CO2 capture performance of the samples was investigated using a thermogravimetric analysis (TGA). It was found that in both modification techniques, the presence of nitrogen functionalities on carbon surface generally increased the CO2 adsorption capacity. The results indicated that oxidation followed by high temperature ammonia treatment (800 °C) considerably enhanced the CO2 uptake at higher temperatures.

  8. Morphology inherence from hollow MOFs to hollow carbon polyhedrons in preparing carbon-based electrocatalysts

    DOE PAGES

    Pei, Yuchen; Qi, Zhiyuan; Li, Xinle; ...

    2017-02-21

    Hollow carbon nanostructures are emerging as advanced electrocatalysts for the oxygen reduction reaction (ORR) due to the effective usage of active sites and the reduced dependence on expensive noble metals. Conventional preparation of these hollow structures is achieved through templates (e.g. SiO 2, CdS, and Ni 3C), which serve to retain the void interiors during carbonization, leading to an essential template-removal procedure using hazardous chemical etchants. Herein, we demonstrate the direct carbonization of unique hollow zeolitic imidazolate frameworks (ZIFs) for the synthesis of hollow carbon polyhedrons (HCPs) with well-defined morphologies. The hollow ZIF particles behave bi-functionally as a carbon sourcemore » and a morphology directing agent. This method evidences the strong morphology inherence from the hollow ZIFs during the carbonization, advancing the significant simplicity and environmental friendliness of this synthesis strategy. The as-prepared HCPs show a uniform polyhedral morphology and large void interiors, which enable their superior ORR activity. Iron can be doped into the HCPs (Fe/HCPs), providing the Fe/HCPs with enhanced ORR properties ( E 1/2 = 0.850 V) in comparison with those of HCPs. As a result, we highlight the efficient structural engineering to transform ZIFs into advanced carbon nanostructures accomplishing morphological control and high electrocatalytic activity.« less

  9. Morphology inherence from hollow MOFs to hollow carbon polyhedrons in preparing carbon-based electrocatalysts

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Pei, Yuchen; Qi, Zhiyuan; Li, Xinle

    Hollow carbon nanostructures are emerging as advanced electrocatalysts for the oxygen reduction reaction (ORR) due to the effective usage of active sites and the reduced dependence on expensive noble metals. Conventional preparation of these hollow structures is achieved through templates (e.g. SiO 2, CdS, and Ni 3C), which serve to retain the void interiors during carbonization, leading to an essential template-removal procedure using hazardous chemical etchants. Herein, we demonstrate the direct carbonization of unique hollow zeolitic imidazolate frameworks (ZIFs) for the synthesis of hollow carbon polyhedrons (HCPs) with well-defined morphologies. The hollow ZIF particles behave bi-functionally as a carbon sourcemore » and a morphology directing agent. This method evidences the strong morphology inherence from the hollow ZIFs during the carbonization, advancing the significant simplicity and environmental friendliness of this synthesis strategy. The as-prepared HCPs show a uniform polyhedral morphology and large void interiors, which enable their superior ORR activity. Iron can be doped into the HCPs (Fe/HCPs), providing the Fe/HCPs with enhanced ORR properties ( E 1/2 = 0.850 V) in comparison with those of HCPs. As a result, we highlight the efficient structural engineering to transform ZIFs into advanced carbon nanostructures accomplishing morphological control and high electrocatalytic activity.« less

  10. Magnetic properties and transmission electron microscopy studies of Ni nanoparticles encapsulated in carbon nanocages and carbon nanotubes

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    He Chunnian; Zhao Naiqin; Shi Chunsheng

    2008-08-04

    Three types of carbon nanomaterials, including bamboo-shaped carbon nanotubes with Ni encapsulated and hollow and Ni catalytic particles filled carbon nanocages, have been prepared by methane catalytic decomposition at a relatively low temperature. Transmission electron microscopy observations showed that fascinating fullerene-like Ni-C (graphitic) core-shell nanostructures predominated. Detailed examination of high-resolution transmission electron microscopy showed that the walls of bamboo-shaped carbon nanotubes with quasi-cone catalytic particles encapsulated consisted of oblique graphene planes with respect to the tube axis. The Ni particles encapsulated in the carbon nanocages were larger than that encapsulated in carbon nanotubes, but the diameters of the cores ofmore » hollow carbon nanocages were less than that of Ni particles encapsulated in carbon nanotubes, suggesting that the sizes of catalyst particles played an important role during carbon nanomaterial growth. The magnetic properties of the carbon nanomaterials were measured, which showed relatively large coercive force (H{sub c} = 138.4 O{sub e}) and good ferromagnetism (M{sub r}/M{sub s} = 0.325)« less

  11. Microbial Enzyme Activity and Carbon Cycling in Grassland Soil Fractions

    NASA Astrophysics Data System (ADS)

    Allison, S. D.; Jastrow, J. D.

    2004-12-01

    Extracellular enzymes are necessary to degrade complex organic compounds present in soils. Using physical fractionation procedures, we tested whether old soil carbon is spatially isolated from degradative enzymes across a prairie restoration chronosequence in Illinois, USA. We found that carbon-degrading enzymes were abundant in all soil fractions, including macroaggregates, microaggregates, and the clay fraction, which contains carbon with a mean residence time of ~200 years. The activities of two cellulose-degrading enzymes and a chitin-degrading enzyme were 2-10 times greater in organic matter fractions than in bulk soil, consistent with the rapid turnover of these fractions. Polyphenol oxidase activity was 3 times greater in the clay fraction than in the bulk soil, despite very slow carbon turnover in this fraction. Changes in enzyme activity across the restoration chronosequence were small once adjusted for increases in soil carbon concentration, although polyphenol oxidase activity per unit carbon declined by 50% in native prairie versus cultivated soil. These results are consistent with a `two-pool' model of enzyme and carbon turnover in grassland soils. In light organic matter fractions, enzyme production and carbon turnover both occur rapidly. However, in mineral-dominated fractions, both enzymes and their carbon substrates are immobilized on mineral surfaces, leading to slow turnover. Soil carbon accumulation in the clay fraction and across the prairie restoration chronosequence probably reflects increasing physical isolation of enzymes and substrates on the molecular scale, rather than the micron to millimeter scale.

  12. Evidence for Reduced, Carbon-rich Regions in the Solar Nebula from an Unusual Cometary Dust Particle

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    De Gregorio, Bradley T.; Stroud, Rhonda M.; Nittler, Larry R.

    Geochemical indicators in meteorites imply that most formed under relatively oxidizing conditions. However, some planetary materials, such as the enstatite chondrites, aubrite achondrites, and Mercury, were produced in reduced nebular environments. Because of large-scale radial nebular mixing, comets and other Kuiper Belt objects likely contain some primitive material related to these reduced planetary bodies. Here, we describe an unusual assemblage in a dust particle from comet 81P/Wild 2 captured in silica aerogel by the NASA Stardust spacecraft. The bulk of this ∼20 μ m particle is comprised of an aggregate of nanoparticulate Cr-rich magnetite, containing opaque sub-domains composed of poorlymore » graphitized carbon (PGC). The PGC forms conformal shells around tiny 5–15 nm core grains of Fe carbide. The C, N, and O isotopic compositions of these components are identical within errors to terrestrial standards, indicating a formation inside the solar system. Magnetite compositions are consistent with oxidation of reduced metal, similar to that seen in enstatite chondrites. Similarly, the core–shell structure of the carbide + PGC inclusions suggests a formation via FTT reactions on the surface of metal or carbide grains in warm, reduced regions of the solar nebula. Together, the nanoscale assemblage in the cometary particle is most consistent with the alteration of primary solids condensed from a C-rich, reduced nebular gas. The nanoparticulate components in the cometary particle provide the first direct evidence from comets of reduced, carbon-rich regions that were present in the solar nebula.« less

  13. The influence of human physical activity and contaminated clothing type on particle resuspension.

    PubMed

    McDonagh, A; Byrne, M A

    2014-01-01

    A study was conducted to experimentally quantify the influence of three variables on the level of resuspension of hazardous aerosol particles from clothing. Variables investigated include physical activity level (two levels, low and high), surface type (four different clothing material types), and time i.e. the rate at which particles resuspend. A mixture of three monodisperse tracer-labelled powders, with median diameters of 3, 5, and 10 microns, was used to "contaminate" the samples, and the resuspended particles were analysed in real-time using an Aerodynamic Particle Sizer (APS), and also by Neutron Activation Analysis (NAA). The overall finding was that physical activity resulted in up to 67% of the contamination deposited on clothing being resuspended back into the air. A detailed examination of the influence of physical activity level on resuspension, from NAA, revealed that the average resuspended fraction (RF) of particles at low physical activity was 28 ± 8%, and at high physical activity was 30 ± 7%, while the APS data revealed a tenfold increase in the cumulative mass of airborne particles during high physical activity in comparison to that during low physical activity. The results also suggest that it is not the contaminated clothing's fibre type which influences particle resuspension, but the material's weave pattern (and hence the material's surface texture). Investigation of the time variation in resuspended particle concentrations indicated that the data were separable into two distinct regimes: the first (occurring within the first 1.5 min) having a high, positive rate of change of airborne particle concentration relative to the second regime. The second regime revealed a slower rate of change of particle concentration and remained relatively unchanged for the remainder of each resuspension event. Copyright © 2013 Elsevier Ltd. All rights reserved.

  14. Single Atomic Iron Catalysts for Oxygen Reduction in Acidic Media: Particle Size Control and Thermal Activation

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zhang, Hanguang; Hwang, Sooyeon; Wang, Maoyu

    It remains a grand challenge to replace platinum group metal (PGM) catalysts with earth-abundant materials for the oxygen reduction reaction (ORR) in acidic media, which is crucial for large-scale deployment of proton exchange membrane fuel cells (PEMFCs). Here, we report a high-performance atomic Fe catalyst derived from chemically Fe-doped zeolitic imidazolate frameworks (ZIFs) by directly bonding Fe ions to imidazolate ligands within 3D frameworks. Although the ZIF was identified as a promising precursor, the new synthetic chemistry enables the creation of well-dispersed atomic Fe sites embedded into porous carbon without the formation of aggregates. The size of catalyst particles ismore » tunable through synthesizing Fe-doped ZIF nanocrystal precursors in a wide range from 20 to 1000 nm followed by one-step thermal activation. Similar to Pt nanoparticles, the unique size control without altering chemical properties afforded by this approach is able to increase the number of PGM-free active sites. The best ORR activity is measured with the catalyst at a size of 50 nm. Further size reduction to 20 nm leads to significant particle agglomeration, thus decreasing the activity. Using the homogeneous atomic Fe model catalysts, we elucidated the active site formation process through correlating measured ORR activity with the change of chemical bonds in precursors during thermal activation up to 1100 °C. The critical temperature to form active sites is 800 °C, which is associated with a new Fe species with a reduced oxidation number (from Fe3+ to Fe2+) likely bonded with pyridinic N (FeN4) embedded into the carbon planes. Further increasing the temperature leads to continuously enhanced activity, linked to the rise of graphitic N and Fe–N species. The new atomic Fe catalyst has achieved respectable ORR activity in challenging acidic media (0.5 M H2SO4), showing a half-wave potential of 0.85 V vs RHE and leaving only a 30 mV gap with Pt/C (60 μgPt/cm2). Enhanced

  15. Single Atomic Iron Catalysts for Oxygen Reduction in Acidic Media: Particle Size Control and Thermal Activation

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zhang, Hanguang; Hwang, Sooyeon; Wang, Maoyu

    It remains a grand challenge to replace platinum group metal (PGM) catalysts with earth-abundant materials for the oxygen reduction reaction (ORR) in acidic media, which is crucial for large-scale deployment of proton exchange membrane fuel cells (PEMFCs). We report a high-performance atomic Fe catalyst derived from chemically Fe-doped zeolitic imidazolate frameworks (ZIFs) by directly bonding Fe ions to imidazolate ligands within 3D frameworks. Although the ZIF was identified as a promising precursor, the new synthetic chemistry enables the creation of well-dispersed atomic Fe sites embedded into porous carbon without the formation of aggregates. The size of catalyst particles is tunablemore » through synthesizing Fe-doped ZIF nanocrystal precursors in a wide range from 20 to 1000 nm followed by one-step thermal activation. Similar to Pt nanoparticles, the unique size control without altering chemical properties afforded by this approach is able to increase the number of PGM-free active sites. The best ORR activity is measured with the catalyst at a size of 50 nm. Further size reduction to 20 nm leads to significant particle agglomeration, thus decreasing the activity. In using the homogeneous atomic Fe model catalysts, we elucidated the active site formation process through correlating measured ORR activity with the change of chemical bonds in precursors during thermal activation up to 1100 °C. The critical temperature to form active sites is 800 °C, which is associated with a new Fe species with a reduced oxidation number (from Fe 3+ to Fe 2+) likely bonded with pyridinic N (FeN 4) embedded into the carbon planes. Further increasing the temperature leads to continuously enhanced activity, linked to the rise of graphitic N and Fe–N species. The new atomic Fe catalyst has achieved respectable ORR activity in challenging acidic media (0.5 M H 2SO 4), showing a half-wave potential of 0.85 V vs RHE and leaving only a 30 mV gap with Pt/C (60 μg Pt/cm 2

  16. Single Atomic Iron Catalysts for Oxygen Reduction in Acidic Media: Particle Size Control and Thermal Activation

    DOE PAGES

    Zhang, Hanguang; Hwang, Sooyeon; Wang, Maoyu; ...

    2017-09-13

    It remains a grand challenge to replace platinum group metal (PGM) catalysts with earth-abundant materials for the oxygen reduction reaction (ORR) in acidic media, which is crucial for large-scale deployment of proton exchange membrane fuel cells (PEMFCs). We report a high-performance atomic Fe catalyst derived from chemically Fe-doped zeolitic imidazolate frameworks (ZIFs) by directly bonding Fe ions to imidazolate ligands within 3D frameworks. Although the ZIF was identified as a promising precursor, the new synthetic chemistry enables the creation of well-dispersed atomic Fe sites embedded into porous carbon without the formation of aggregates. The size of catalyst particles is tunablemore » through synthesizing Fe-doped ZIF nanocrystal precursors in a wide range from 20 to 1000 nm followed by one-step thermal activation. Similar to Pt nanoparticles, the unique size control without altering chemical properties afforded by this approach is able to increase the number of PGM-free active sites. The best ORR activity is measured with the catalyst at a size of 50 nm. Further size reduction to 20 nm leads to significant particle agglomeration, thus decreasing the activity. In using the homogeneous atomic Fe model catalysts, we elucidated the active site formation process through correlating measured ORR activity with the change of chemical bonds in precursors during thermal activation up to 1100 °C. The critical temperature to form active sites is 800 °C, which is associated with a new Fe species with a reduced oxidation number (from Fe 3+ to Fe 2+) likely bonded with pyridinic N (FeN 4) embedded into the carbon planes. Further increasing the temperature leads to continuously enhanced activity, linked to the rise of graphitic N and Fe–N species. The new atomic Fe catalyst has achieved respectable ORR activity in challenging acidic media (0.5 M H 2SO 4), showing a half-wave potential of 0.85 V vs RHE and leaving only a 30 mV gap with Pt/C (60 μg Pt/cm 2

  17. Black Carbon Particle Number Distribution Measurements during the ATHENS-2013 Winter Campaign

    NASA Astrophysics Data System (ADS)

    Gkatzelis, Georgios; Papanastasiou, Dimitris; Florou, Kalliopi; Kaltsonoudis, Christos; Louvaris, Eyaggelos; Bezentakos, Spiridon; Biskos, Georgios; Pandis, Spuros

    2014-05-01

    Black Carbon (BC) particles emitted by anthropogenic sources play an important role both in climate change and in air quality degradation. Open burning in forests and savannas, combustion of diesel and solid fuels for cooking and heating in homes represent the majority of BC emissions. Earlier work has focused on the BC atmospheric direct radiative forcing that is mostly related to its mass concentration and optical properties of the corresponding particles. A variety of measurement techniques are used to measure the mass concentration of BC by taking advantage of its optical or physical properties. Moreover, the carbonaceous particles containing BC are also important for the indirect forcing of climate. This effect is mostly related to the number concentration of BC particles. The number distribution of BC particles especially below 100 nm is quite uncertain due to limitations of the existing measurement techniques. In this work we employed a thermodenuder-based method as an approach for the measurement of the BC number distribution. More specifically, we combined a thermodenuder (TD) operating at temperatures up to 300 ° C, with a Scanning Mobility Particle Sizer (SMPS) and a High Resolution Time of Flight Aerosol Mass Spectrometer (HR-ToF AMS). Aerosol size and composition measurements were carried out both at ambient and at elevated TD temperatures in Athens field campaign during January and February of 2013. In parallel, a Multi-Angle Absorption Photometer (MAAP) provided information about the BC mass concentration while a Hygroscopic Tandem Differential Mobility Analyzer (HTDMA) measured the mixing state and the hygroscopicity of the particles as a function of their size. These measurements were then combined to estimate the number concentration of BC particles. Our analysis focused on different periods during the study. During some of them one source dominated the carbonaceous aerosol concentration. Such periods included rush hour traffic, nighttime wood

  18. Weathering of a carbon nanotube/epoxy nanocomposite under UV light and in water bath: impact on abraded particles

    NASA Astrophysics Data System (ADS)

    Schlagenhauf, Lukas; Kianfar, Bahareh; Buerki-Thurnherr, Tina; Kuo, Yu-Ying; Wichser, Adrian; Nüesch, Frank; Wick, Peter; Wang, Jing

    2015-11-01

    Weathering processes can influence the surface properties of composites with incorporated nanoparticles. These changes may affect the release behavior of nanoparticles when an abrasion process is applied. Therefore, the influence of two different weathering processes, immersion in water and exposure to UV light, on the properties of abraded particles from a carbon nanotube (CNT)/epoxy nanocomposite was investigated. The investigation included the measurement of the weathering impact on the surface chemistry of the exposed samples, the particle size of abraded particles, the quantity of exposed CNTs in the respirable part of the abraded particles, and the toxicity of abraded particles, measured by in vitro toxicity tests using the THP-1 monocyte-derived macrophages. The results showed that weathering by immersion in water had no influence on the properties of abraded particles. The exposure to UV light caused a degradation of the epoxy on the surface, followed by delamination of an approx. 2.5 μm thick layer. An increased quantity of exposed CNTs in abraded particles was not found; on the contrary, longer UV exposure times decreased the released fraction of CNTs from 0.6% to 0.4%. The toxicity tests revealed that abraded particles from the nanocomposites did not induce additional acute cytotoxic effects compared to particles from the neat epoxy.Weathering processes can influence the surface properties of composites with incorporated nanoparticles. These changes may affect the release behavior of nanoparticles when an abrasion process is applied. Therefore, the influence of two different weathering processes, immersion in water and exposure to UV light, on the properties of abraded particles from a carbon nanotube (CNT)/epoxy nanocomposite was investigated. The investigation included the measurement of the weathering impact on the surface chemistry of the exposed samples, the particle size of abraded particles, the quantity of exposed CNTs in the respirable part of

  19. Activated Carbon Preparation and Modification for Adsorption

    NASA Astrophysics Data System (ADS)

    Cao, Yuhe

    Butanol is considered a promising, infrastructure-compatible biofuel. Butanol has a higher energy content than ethanol and can be used in conventional gas engines without modifications. Unfortunately, the fermentation pathway for butanol production is restricted by its toxicity to the microbial strains used in the process. Butanol is toxic to the microbes, and this can slow fermentation rates and reduce butanol yields. Gas stripping technology can efficiently remove butanol from the fermentation broth as it is produced, thereby decreasing its inhibitory effects. Traditional butanol separation heavily depends on the energy intensive distillation method. One of the main issues in acetone-butanol-ethanol fermentation is that butanol concentrations in the fermentation broth are low, ranging from 1 to 1.2 percent in weight, because of its toxicity to the microorganisms. Therefore distillation of butanol is even worse than distillation of corn ethanol. Even new separation methods, such as solid- extraction methods involve adding substances, such as polymer resin and zeolite or activated carbon, to biobutanol fermentatioon broth did not achieve energy efficient separation of butanol due to low adsorption selectivity and fouling in broth. Gas-stripping - condensation is another new butanol recovery method, however, the butanol in gas-stripping stream is too low to be condensed without using expensive and energy intensive liquid nitrogen. Adsorption can then be used to recover butanol from the vapor phase. Activated carbon (AC) samples and zeolite were investigated for their butanol vapor adsorption capacities. Commercial activated carbon was modified via hydrothermal H2O2 treatment, and the specific surface area and oxygen-containing functional groups of activated carbon were tested before and after treatment. Hydrothermal H2O 2 modification increased the surface oxygen content, Brunauer-Emmett-Teller surface area, micropore volume, and total pore volume of active carbon

  20. Activated carbons from potato peels: The role of activation agent and carbonization temperature of biomass on their use as sorbents for bisphenol A uptake from aqueous solutions

    NASA Astrophysics Data System (ADS)

    Arampatzidou, An; Deliyanni, Eleni A.

    2015-04-01

    Activated carbons prepared from potato peels, a solid waste by product, and activated with different activating chemicals, have been studied for the adsorption of an endocrine disruptor (Bisphenol-A) from aqueous solutions. The potato peels biomass was activated with phosphoric acid, KOH and ZnCl2. The different activating chemicals were tested in order the better activation agent to be found. The carbons were carbonized by pyrolysis, in one step procedure, at three different temperatures in order the role of the temperature of carbonization to be pointed out. The porous texture and the surface chemistry of the prepared activated carbons were characterized by Nitrogen adsorption (BET), Scanning Electron Microscope (SEM), thermal analysis (DTA) and Fourier Transform Infrared Spectroscopy (FTIR). Batch experiments were performed to investigate the effect of pH, the adsorbent dose, the initial bisphenol A concentration and temperature. Equilibrium adsorption data were analyzed by Langmuir and Freundlich isotherms. The thermodynamic parameters such as the change of enthalpy (ΔH0), entropy (ΔS0) and Gibb's free energy (ΔG0) of adsorption systems were also evaluated. The adsorption capacity calculated from the Langmuir isotherm was found to be 450 mg g-1 at an initial pH 3 at 25 °C for the phosphoric acid activated carbon, that make the activated carbon a promising adsorbent material.

  1. Exposure for ultrafine carbon particles at levels below detectable pulmonary inflammation affects cardiovascular performance in spontaneously hypertensive rats*

    EPA Science Inventory

    Rationale: Exposure to particulate matter is a risk factor for cardiopulmonary disease but the related molecular mechanisms are poorly understood. Previously we studied cardiovascular responses in healthy WKY rats following inhalation exposure to ultrafine carbon particles (UfCPs...

  2. Comparison on pore development of activated carbon produced by chemical and physical activation from palm empty fruit bunch

    NASA Astrophysics Data System (ADS)

    Hidayat, A.; Sutrisno, B.

    2016-11-01

    It is well-known that activated carbon is considered to be the general adsorbent due to the large range of applications. Numerous works are being continuously published concerning its use as adsorbent for: treatment of potable water; purification of air; retention of toxins by respirators; removal of organic and inorganic pollutants from flue gases and industrial waste gases and water; recuperation of solvents and hydrocarbons volatilized from petroleum derivatives; catalysis; separation of gas mixtures (molecularsieve activated carbons); storage of natural gas and hydrogen; energy storage in supercapacitors; recovery of gold, silver and othernoble metals; etc. This work presents producing activated carbons from palm empty fruit bunch using both physical activation with CO2 and chemical activation with KOH. The resultant activated carbons were characterized by measuring their porosities and pore size distributions. A comparison of the textural characteristics and surface chemistry of the activated carbon from palm empty fruit bunch by the CO2 and the KOH activation leads to the following findings: An activated carbon by the CO2 activation under the optimum conditions has a BET surface area of 717 m2/g, while that by the KOH activation has a BET surface area of 613 m2/g. The CO2 activation generated a highly microporous carbon (92%) with a Type-I isotherm, while the KOH activation generated a mesoporous one (70%) with a type-IV isotherm, the pore volumes are 0.2135 and 0.7426 cm3.g-1 respectively. The average pore size of the activated carbons is 2.72 and 2.56 nm for KOH activation and CO2 activation, respectively. The FT-IR spectra indicated significant variation in the surface functional groups are quite different for the KOH activated and CO2 activated carbons.

  3. Downward particle flux and carbon export in the Beaufort Sea, Arctic Ocean; the role of zooplankton

    NASA Astrophysics Data System (ADS)

    Miquel, J.-C.; Gasser, B.; Martín, J.; Marec, C.; Babin, M.; Fortier, L.; Forest, A.

    2015-08-01

    As part of the international, multidisciplinary project Malina, downward particle fluxes were investigated by means of a drifting multi-sediment trap mooring deployed at three sites in the Canadian Beaufort Sea in late summer 2009. Mooring deployments lasted between 28 and 50 h and targeted the shelf-break and the slope along the Beaufort-Mackenzie continental margin, as well as the edge between the Mackenzie Shelf and the Amundsen Gulf. Besides analyses of C and N, the collected material was investigated for pigments, phyto- and microzooplankton, faecal pellets and swimmers. The measured fluxes were relatively low, in the range of 11-54 mg m-2 d-1 for the total mass, 1-15 mg C m-2 d-1 for organic carbon and 0.2-2.5 mg N m-2 d-1 for nitrogen. Comparison with a long-term trap data set from the same sampling area showed that the short-term measurements were at the lower end of the high variability characterizing a rather high flux regime during the study period. The sinking material consisted of aggregates and particles that were characterized by the presence of hetero- and autotrophic microzooplankters and diatoms and by the corresponding pigment signatures. Faecal pellets contribution to sinking carbon flux was important, especially at depths below 100 m, where they represented up to 25 % of the total carbon flux. The vertical distribution of different morphotypes of pellets showed a marked pattern with cylindrical faeces (produced by calanoid copepods) present mainly within the euphotic zone, whereas elliptical pellets (produced mainly by smaller copepods) were more abundant at mesopelagic depths. These features, together with the density of matter within the pellets, highlighted the role of the zooplankton community in the transformation of carbon issued from the primary production and the transition of that carbon from the productive surface zone to the Arctic Ocean's interior. Our data indicate that sinking carbon flux in this late summer period is primarily

  4. Active particles in complex and crowded environments

    DOE PAGES

    Bechinger, Clemens; Di Leonardo, Roberto; Löwen, Hartmut; ...

    2016-11-23

    Differently from passive Brownian particles, active particles, also known as self-propelled Brownian particles or microswimmers and nanoswimmers, are capable of taking up energy from their environment and converting it into directed motion. Because of this constant flow of energy, their behavior can be explained and understood only within the framework of nonequilibrium physics. In the biological realm, many cells perform directed motion, for example, as a way to browse for nutrients or to avoid toxins. Inspired by these motile microorganisms, researchers have been developing artificial particles that feature similar swimming behaviors based on different mechanisms. These man-made micromachines and nanomachinesmore » hold a great potential as autonomous agents for health care, sustainability, and security applications. Finally, with a focus on the basic physical features of the interactions of self-propelled Brownian particles with a crowded and complex environment, this comprehensive review will provide a guided tour through its basic principles, the development of artificial self-propelling microparticles and nanoparticles, and their application to the study of nonequilibrium phenomena, as well as the open challenges that the field is currently facing.« less

  5. Activated carbon amendment for in-situ remediation

    NASA Astrophysics Data System (ADS)

    Elmquist, M.; Brändli, R.; Henriksen, T.; Hartnik, T.; Cornelissen, G.

    2009-04-01

    easy technique that can be performed to a relatively low cost. However, the AC particles may also sorb other constituents of the effluent water such as DOC and nutrients which in turn may lead to reduced plant growth rate. Therefore, the long-term effects of this amendment technique have to be studied more closely. Reference Rahel C. Brändli, Thomas Hartnik, Thomas Henriksen, Gerard Cornelissen, (2008) Sorption of native polyaromatic hydrocarbons (PAH) to black carbon and amended activated carbon in soil, Chemosphere doi:10.1016/j.chemosphere.2008.08.034

  6. Comparison of adsorption behavior of PCDD/Fs on carbon nanotubes and activated carbons in a bench-scale dioxin generating system.

    PubMed

    Zhou, Xujian; Li, Xiaodong; Xu, Shuaixi; Zhao, Xiyuan; Ni, Mingjiang; Cen, Kefa

    2015-07-01

    Porous carbon-based materials are commonly used to remove various organic and inorganic pollutants from gaseous and liquid effluents and products. In this study, the adsorption of dioxins on both activated carbons and multi-walled carbon nanotube was internally compared, via series of bench scale experiments. A laboratory-scale dioxin generator was applied to generate PCDD/Fs with constant concentration (8.3 ng I-TEQ/Nm(3)). The results confirm that high-chlorinated congeners are more easily adsorbed on both activated carbons and carbon nanotubes than low-chlorinated congeners. Carbon nanotubes also achieved higher adsorption efficiency than activated carbons even though they have smaller BET-surface. Carbon nanotubes reached the total removal efficiency over 86.8 % to be compared with removal efficiencies of only 70.0 and 54.2 % for the two other activated carbons tested. In addition, because of different adsorption mechanisms, the removal efficiencies of carbon nanotubes dropped more slowly with time than was the case for activated carbons. It could be attributed to the abundant mesopores distributed in the surface of carbon nanotubes. They enhanced the pore filled process of dioxin molecules during adsorption. In addition, strong interactions between the two benzene rings of dioxin molecules and the hexagonal arrays of carbon atoms in the surface make carbon nanotubes have bigger adsorption capacity.

  7. Synthesis and characterization of carbon nanotube from coconut shells activated carbon

    NASA Astrophysics Data System (ADS)

    Melati, A.; Hidayati, E.

    2016-03-01

    Carbon nanotubes (CNTs) have been explored in almost every single cancer treatment modality, including drug delivery, lymphatic targeted chemotherapy, photodynamic therapy, and gene therapy. They are considered as one of the most promising nanomaterial with the capability of both detecting the cancerous cells and delivering drugs or small therapeutic molecules to the cells. CNTs have unique physical and chemical properties such as high aspect ratio, ultralight weight, high mechanical strength, high electrical conductivity, and high thermal conductivity. Coconut Shell was researched as active carbon source on 500 - 600°C. These activated carbon was synthesized becomes carbon nanotube and have been proposed as a promising tool for detecting the expression of indicative biological molecules at early stage of cancer. Clinically, biomarkers cancer can be detected by CNT Biosensor. We are using pyrolysis methods combined with CVD process or Wet Chemical Process on 600°C. Our team has successfully obtained high purity, and aligned MWCNT (Multi Wall Nanotube) bundles on synthesis CNT based on coconut shells raw materials. CNTs can be used to cross the mammalian cell membrane by endocytosis or other mechanisms. SEM characterization of these materials have 179 nm bundles on phase 83° and their materials compound known by using FTIR characterization.

  8. Granular activated carbons from broiler manure: physical, chemical and adsorptive properties.

    PubMed

    Lima, Isabel M; Marshall, Wayne E

    2005-04-01

    Broiler manure produced at large concentrated facilities poses risks to the quality of water and public health. This study utilizes broiler litter and cake as source materials for granular activated carbon production and optimizes conditions for their production. Pelletized manure samples were pyrolyzed at 700 degrees C for 1 h followed by activation in an inert atmosphere under steam at different water flow rates, for a period ranging from 15 to 75 min. Carbon physical and adsorptive properties were dependent on activation time and quantity of steam used as activant, yields varied from 18% to 28%, surface area varied from 253 to 548 m2/g and copper ion adsorption varied from 0.13 to 1.92 mmol Cu2+/g carbon. Best overall performing carbons were steam activated for 45 min at 3 ml/min. Comparative studies with commercial carbons revealed the broiler cake-based carbon as having the highest copper ion efficiency.

  9. Geometrical influence of a deposited particle on the performance of bridged carbon nanotube-based mass detectors

    NASA Astrophysics Data System (ADS)

    Ali-Akbari, H. R.; Ceballes, S.; Abdelkefi, A.

    2017-10-01

    A nonlocal continuum-based model is derived to simulate the dynamic behavior of bridged carbon nanotube-based nano-scale mass detectors. The carbon nanotube (CNT) is modeled as an elastic Euler-Bernoulli beam considering von-Kármán type geometric nonlinearity. In order to achieve better accuracy in characterization of the CNTs, the geometrical properties of an attached nano-scale particle are introduced into the model by its moment of inertia with respect to the central axis of the beam. The inter-atomic long-range interactions within the structure of the CNT are incorporated into the model using Eringen's nonlocal elastic field theory. In this model, the mass can be deposited along an arbitrary length of the CNT. After deriving the full nonlinear equations of motion, the natural frequencies and corresponding mode shapes are extracted based on a linear eigenvalue problem analysis. The results show that the geometry of the attached particle has a significant impact on the dynamic behavior of the CNT-based mechanical resonator, especially, for those with small aspect ratios. The developed model and analysis are beneficial for nano-scale mass identification when a CNT-based mechanical resonator is utilized as a small-scale bio-mass sensor and the deposited particles are those, such as proteins, enzymes, cancer cells, DNA and other nano-scale biological objects with different and complex shapes.

  10. Personal exposure to ultrafine particles: the influence of time-activity patterns.

    PubMed

    Buonanno, G; Stabile, L; Morawska, L

    2014-01-15

    Exposure to ultrafine particles (UFPs) is deemed to be a major risk affecting human health. Therefore, airborne particle studies were performed in the recent years to evaluate the most critical micro-environments, as well as identifying the main UFP sources. Nonetheless, in order to properly evaluate the UFP exposure, personal monitoring is required as the only way to relate particle exposure levels to the activities performed and micro-environments visited. To this purpose, in the present work, the results of experimental analysis aimed at showing the effect of the time-activity patterns on UFP personal exposure are reported. In particular, 24 non-smoking couples (12 during winter and summer time, respectively), comprised of a man who worked full-time and a woman who was a homemaker, were analyzed using personal particle counter and GPS monitors. Each couple was investigated for a 48-h period, during which they also filled out a diary reporting the daily activities performed. Time activity patterns, particle number concentration exposure and the related dose received by the participants, in terms of particle alveolar-deposited surface area, were measured. The average exposure to particle number concentration was higher for women during both summer and winter (Summer: women 1.8 × 10(4) part. cm(-3); men 9.2 × 10(3) part. cm(-3); Winter: women 2.9 × 10(4) part. cm(-3); men 1.3 × 10(4) part. cm(-3)), which was likely due to the time spent undertaking cooking activities. Staying indoors after cooking also led to higher alveolar-deposited surface area dose for both women and men during the winter time (9.12 × 10(2) and 6.33 × 10(2) mm(2), respectively), when indoor ventilation was greatly reduced. The effect of cooking activities was also detected in terms of women's dose intensity (dose per unit time), being 8.6 and 6.6 in winter and summer, respectively. On the contrary, the highest dose intensity activity for men was time spent using transportation (2.8 in

  11. Exposure to particles, elemental carbon and nitrogen dioxide in workers exposed to motor exhaust.

    PubMed

    Lewné, Marie; Plato, Nils; Gustavsson, Per

    2007-11-01

    The main aim of this study was to investigate the personal exposure to diesel and petrol exhaust fumes in occupations when exposure is prevalent and/or high. We also investigated the correlation between the five particle fractions [particles with an aerodynamic diameter <1 microm (PM(1)), particles with an aerodynamic diameter <2.5 microm (PM(2.5)), particles in size 0.1-10 microm, elemental carbon (EC) and total carbon (TC)] and nitrogen dioxide (NO(2)), in the various occupational environments. Seventy-one workers were included in the study. They were subdivided into seven groups depending on working area, working indoors, out of doors or in vehicles and type of exposure (diesel or petrol exhaust). Personal measurements were performed during 3 days per worker. We used five indicators of the particle fraction: PM(1), PM(2.5), particle measured with a real-time monitoring instrument for particles in sizes 0.1 and 10 microm (DataRAM), EC and TC. We used NO(2) as an indicator of the gas phase. Tunnel construction workers showed the highest levels of exposure for all indicators, followed by diesel-exposed garage workers. For the other five groups, the levels were statistically significantly lower, and the differences between the groups were small. The full-shift geometric average of PM(1) varied between 119 microg m(-3) (tunnel construction workers) and 11 microg m(-3) (taxi drivers). For PM(2.5), the levels varied between 231 microg m(-3) (tunnel construction workers) and 16 microg m(-3) (bus and lorry drivers). For the measurements with the real-time monitoring instrument DataRAM, the levels varied between 398 microg m(-3) (tunnel construction workers) and 14 microg m(-3) (taxi drivers). For EC, the levels varied between 87 microg m(-3) (tunnel construction workers) and 4 microg m(-3) (other outdoor workers exposed to diesel exhaust), and for TC, the levels varied between 191 microg m(-3) (tunnel construction workers) and 10 microg m(-3) (taxi drivers). Finally, for

  12. High performance supercapacitor from activated carbon derived from waste orange skin

    NASA Astrophysics Data System (ADS)

    Ahmed, Sultan; Hussain, S.; Ahmed, Ahsan; Rafat, M.

    2018-05-01

    Activated carbon due to its inherent properties such as large surface area and low cost is most frequently used electrode material for supercapacitor. Activated carbon has been previously derived from various biomass such as coconut shell, coffee bean etc. Herein, we report the synthesis of activated carbon from waste orange skin. The material was synthesized employing chemical activation method and the success of synthesis was confirmed by its physical and electrochemical properties. The physical properties of the as-prepared sample were studied using the techniques of XRD, SEM, Raman spectroscopy and N2 adsorption/desorption analysis while its electrochemical properties were studied in two-electrode assembly using liquid electrolyte (consisting of 1 M solution of LiTFSI dispersed in ionic liquid EMITFSI) and employing the techniques of cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic charge- discharge. The synthesized sample of activated carbon exhibits high specific capacitance of 115 F g-1 at 10 mV s-1. Also, the activated carbon electrode shows the retention of ˜75% in initial capacitance value for more than 2000 initial cycles, indicating the as-prepared activated carbon can be profitably used as electrode material for energy storage devices.

  13. Impact of sulfur oxides on mercury capture by activated carbon.

    PubMed

    Presto, Albert A; Granite, Evan J

    2007-09-15

    Recent field tests of mercury removal with activated carbon injection (ACI) have revealed that mercury capture is limited in flue gases containing high concentrations of sulfur oxides (SOx). In order to gain a more complete understanding of the impact of SOx on ACl, mercury capture was tested under varying conditions of SO2 and SO3 concentrations using a packed bed reactor and simulated flue gas (SFG). The final mercury content of the activated carbons is independent of the SO2 concentration in the SFG, but the presence of SO3 inhibits mercury capture even at the lowest concentration tested (20 ppm). The mercury removal capacity decreases as the sulfur content of the used activated carbons increases from 1 to 10%. In one extreme case, an activated carbon with 10% sulfur, prepared by H2SO4 impregnation, shows almost no mercury capacity. The results suggest that mercury and sulfur oxides are in competition for the same binding sites on the carbon surface.

  14. Adsorption of organic compounds onto activated carbons from recycled vegetables biomass.

    PubMed

    Mameli, Anna; Cincotti, Alberto; Lai, Nicola; Crisafulli, Carmelo; Sciré, Salvatore; Cao, Giacomo

    2004-01-01

    The removal of organic species from aqueous solution by activated carbons is investigated. The latter ones are prepared from olive husks and almond shells. A wide range of surface area values are obtained varying temperature and duration of both carbonization and activation steps. The adsorption isotherm of phenol, catechol and 2,6-dichlorophenol involving the activated carbons prepared are obtained at 25 degrees C. The corresponding behavior is quantitatively correlated using classical isotherm, whose parameters are estimated by fitting the equilibrium data. A two component isotherm (phenol/2,6-dichlorophenol) is determined in order to test activated carbon behavior during competitive adsorption.

  15. The single-particle mixing state and cloud scavenging of black carbon: a case study at a high-altitude mountain site in southern China

    NASA Astrophysics Data System (ADS)

    Zhang, Guohua; Lin, Qinhao; Peng, Long; Bi, Xinhui; Chen, Duohong; Li, Mei; Li, Lei; Brechtel, Fred J.; Chen, Jianxin; Yan, Weijun; Wang, Xinming; Peng, Ping'an; Sheng, Guoying; Zhou, Zhen

    2017-12-01

    In the present study, a ground-based counterflow virtual impactor (GCVI) was used to sample cloud droplet residual (cloud RES) particles, while a parallel PM2.5 inlet was used to sample cloud-free or cloud interstitial (cloud INT) particles. The mixing state of black carbon (BC)-containing particles and the mass concentrations of BC in the cloud-free, RES and INT particles were investigated using a single-particle aerosol mass spectrometer (SPAMS) and two aethalometers, respectively, at a mountain site (1690 m a. s. l. ) in southern China. The measured BC-containing particles were extensively internally mixed with sulfate and were scavenged into cloud droplets (with number fractions of 0.05-0.45) to a similar (or slightly lower) extent as all the measured particles (0.07-0.6) over the measured size range of 0.1-1.6 µm. The results indicate the preferential activation of larger particles and/or that the production of secondary compositions shifts the BC-containing particles towards larger sizes. BC-containing particles with an abundance of both sulfate and organics were scavenged less than those with sulfate but limited organics, implying the importance of the mixing state on the incorporation of BC-containing particles into cloud droplets. The mass scavenging efficiency of BC with an average of 33 % was similar for different cloud events independent of the air mass. This is the first time that both the mixing state and cloud scavenging of BC in China have been reported. Our results would improve the knowledge on the concentration, mixing state, and cloud scavenging of BC in the free troposphere.

  16. Impact of pectin esterification on the antimicrobial activity of nisin-loaded pectin particles.

    PubMed

    Krivorotova, Tatjana; Staneviciene, Ramune; Luksa, Juliana; Serviene, Elena; Sereikaite, Jolanta

    2017-01-01

    The relationship between pectin structure and the antimicrobial activity of nisin-loaded pectin particles was examined. The antimicrobial activity of five different nisin-loaded pectin particles, i.e., nisin-loaded high methoxyl pectin, low methoxyl pectin, pectic acid, dodecyl pectin with 5.4 and 25% degree of substitution were tested in the pH range of 4.0-7.0 by agar-diffusion assay and agar plate count methods. It was found that the degree of esterification of carboxyl group of galacturonic acid in pectin molecule is important for the antimicrobial activity of nisin-loaded pectin particles. Nisin-loaded particles prepared using pectic acid or the pectin with low degree of esterification exhibit higher antimicrobial activity than nisin-loaded high methoxyl pectin particles. Pectins with free carboxyl groups or of low degree of esterification are the most suitable for particles preparation. Moreover, nisin-loaded pectin particles were active at close to neutral or neutral pH values. Therefore, they could be effectively applied for food preservation. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 33:245-251, 2017. © 2016 American Institute of Chemical Engineers.

  17. The Transport Properties of Activated Carbon Fibers

    DOE R&D Accomplishments Database

    di Vittorio, S. L.; Dresselhaus, M. S.; Endo, M.; Issi, J-P.; Piraux, L.

    1990-07-01

    The transport properties of activated isotropic pitch-based carbon fibers with surface area 1000 m{sup 2}/g have been investigated. We report preliminary results on the electrical conductivity, the magnetoresistance, the thermal conductivity and the thermopower of these fibers as a function of temperature. Comparisons are made to transport properties of other disordered carbons.

  18. Dynamics of a magnetic active Brownian particle under a uniform magnetic field.

    PubMed

    Vidal-Urquiza, Glenn C; Córdova-Figueroa, Ubaldo M

    2017-11-01

    The dynamics of a magnetic active Brownian particle undergoing three-dimensional Brownian motion, both translation and rotation, under the influence of a uniform magnetic field is investigated. The particle self-propels at a constant speed along its magnetic dipole moment, which reorients due to the interplay between Brownian and magnetic torques, quantified by the Langevin parameter α. In this work, the time-dependent active diffusivity and the crossover time (τ^{cross})-from ballistic to diffusive regimes-are calculated through the time-dependent correlation function of the fluctuations of the propulsion direction. The results reveal that, for any value of α, the particle undergoes a directional (or ballistic) propulsive motion at very short times (t≪τ^{cross}). In this regime, the correlation function decreases linearly with time, and the active diffusivity increases with it. It the opposite time limit (t≫τ^{cross}), the particle moves in a purely diffusive regime with a correlation function that decays asymptotically to zero and an active diffusivity that reaches a constant value equal to the long-time active diffusivity of the particle. As expected in the absence of a magnetic field (α=0), the crossover time is equal to the characteristic time scale for rotational diffusion, τ_{rot}. In the presence of a magnetic field (α>0), the correlation function, the active diffusivity, and the crossover time decrease with increasing α. The magnetic field regulates the regimes of propulsion of the particle. Here, the field reduces the period of time at which the active particle undergoes a directional motion. Consequently, the active particle rapidly reaches a diffusive regime at τ^{cross}≪τ_{rot}. In the limit of weak fields (α≪1), the crossover time decreases quadratically with α, while in the limit of strong fields (α≫1) it decays asymptotically as α^{-1}. The results are in excellent agreement with those obtained by Brownian dynamics

  19. Dynamics of a magnetic active Brownian particle under a uniform magnetic field

    NASA Astrophysics Data System (ADS)

    Vidal-Urquiza, Glenn C.; Córdova-Figueroa, Ubaldo M.

    2017-11-01

    The dynamics of a magnetic active Brownian particle undergoing three-dimensional Brownian motion, both translation and rotation, under the influence of a uniform magnetic field is investigated. The particle self-propels at a constant speed along its magnetic dipole moment, which reorients due to the interplay between Brownian and magnetic torques, quantified by the Langevin parameter α . In this work, the time-dependent active diffusivity and the crossover time (τcross)—from ballistic to diffusive regimes—are calculated through the time-dependent correlation function of the fluctuations of the propulsion direction. The results reveal that, for any value of α , the particle undergoes a directional (or ballistic) propulsive motion at very short times (t ≪τcross ). In this regime, the correlation function decreases linearly with time, and the active diffusivity increases with it. It the opposite time limit (t ≫τcross ), the particle moves in a purely diffusive regime with a correlation function that decays asymptotically to zero and an active diffusivity that reaches a constant value equal to the long-time active diffusivity of the particle. As expected in the absence of a magnetic field (α =0 ), the crossover time is equal to the characteristic time scale for rotational diffusion, τrot. In the presence of a magnetic field (α >0 ), the correlation function, the active diffusivity, and the crossover time decrease with increasing α . The magnetic field regulates the regimes of propulsion of the particle. Here, the field reduces the period of time at which the active particle undergoes a directional motion. Consequently, the active particle rapidly reaches a diffusive regime at τcross≪τrot . In the limit of weak fields (α ≪1 ), the crossover time decreases quadratically with α , while in the limit of strong fields (α ≫1 ) it decays asymptotically as α-1. The results are in excellent agreement with those obtained by Brownian dynamics

  20. Final Report for Geometric Observers and Particle Filtering for Controlled Active Vision

    DTIC Science & Technology

    2016-12-15

    code) 15-12-2016 Final Report 01Sep06 - 09May11 Final Report for Geometric Observers & Particle Filtering for Controlled Active Vision 49414-NS.1Allen...Observers and Particle Filtering for Controlled Active Vision by Allen R. Tannenbaum School of Electrical and Computer Engineering Georgia Institute of...7 2.2.4 Conformal Area Minimizing Flows . . . . . . . . . . . . . . . . . . . . . . . 8 2.3 Particle Filters

  1. Adsorption kinetics of SO2 on powder activated carbon

    NASA Astrophysics Data System (ADS)

    Li, Bing; Zhang, Qilong; Ma, Chunyuan

    2018-02-01

    The flue gas SO2 adsorption removal by powder activated carbon is investigated based on a fixed bed reactor. The effect of SO2 inlet concentration on SO2 adsorption is investigated and the adsorption kinetics is analyzed. The results indicated that the initial SO2 adsorption rate and the amount of SO2 adsorbed have increased with increased in SO2 inlet concentration. Gas diffusion, surface adsorption and catalytic oxidation reaction are involved in SO2 adsorption on powder activated carbon, which play a different role in different stage. The Bangham kinetics model can be used to predict the kinetics of SO2 adsorption on powder activated carbon.

  2. Activated Carbon Textile via Chemistry of Metal Extraction for Supercapacitors.

    PubMed

    Lam, Do Van; Jo, Kyungmin; Kim, Chang-Hyun; Kim, Jae-Hyun; Lee, Hak-Joo; Lee, Seung-Mo

    2016-12-27

    Carbothermic reduction in the chemistry of metal extraction (MO(s) + C(s) → M(s) + CO(g)) using carbon as a sacrificial agent has been used to smelt metals from diverse oxide ores since ancient times. Here, we paid attention to another aspect of the carbothermic reduction to prepare an activated carbon textile for high-rate-performance supercapacitors. On the basis of thermodynamic reducibility of metal oxides reported by Ellingham, we employed not carbon, but metal oxide as a sacrificial agent in order to prepare an activated carbon textile. We conformally coated ZnO on a bare cotton textile using atomic layer deposition, followed by pyrolysis at high temperature (C(s) + ZnO(s) → C'(s) + Zn(g) + CO(g)). We figured out that it leads to concurrent carbonization and activation in a chemical as well as mechanical way. Particularly, the combined effects of mechanical buckling and fracture that occurred between ZnO and cotton turned out to play an important role in carbonizing and activating the cotton textile, thereby significantly increasing surface area (nearly 10 times) compared with the cotton textile prepared without ZnO. The carbon textiles prepared by carbothermic reduction showed impressive combination properties of high power and energy densities (over 20-fold increase) together with high cyclic stability.

  3. The fate of calcium carbonate nanoparticles administered by oral route: absorption and their interaction with biological matrices.

    PubMed

    Lee, Jeong-A; Kim, Mi-Kyung; Kim, Hyoung-Mi; Lee, Jong Kwon; Jeong, Jayoung; Kim, Young-Rok; Oh, Jae-Min; Choi, Soo-Jin

    2015-01-01

    Orally administered particles rapidly interact with biological fluids containing proteins, enzymes, electrolytes, and other biomolecules to eventually form particles covered by a corona, and this corona potentially affects particle uptake, fate, absorption, distribution, and elimination in vivo. This study explored relationships between the biological interactions of calcium carbonate particles and their biokinetics. We examined the effects of food grade calcium carbonates of different particle size (nano [N-Cal] and bulk [B-Cal]: specific surface areas of 15.8 and 0.83 m(2)/g, respectively) on biological interactions in in vitro simulated physiological fluids, ex vivo biofluids, and in vivo in gastrointestinal fluid. Moreover, absorption and tissue distribution of calcium carbonates were evaluated following a single dose oral administration to rats. N-Cal interacted more with biomatrices than bulk materials in vitro and ex vivo, as evidenced by high fluorescence quenching ratios, but it did not interact more actively with biomatrices in vivo. Analysis of coronas revealed that immunoglobulin, apolipoprotein, thrombin, and fibrinogen, were the major corona proteins, regardless of particle size. A biokinetic study revealed that orally delivered N-Cal was more rapidly absorbed into the blood stream than B-Cal, but no significant differences were observed between the two in terms of absorption efficiencies or tissue distributions. Both calcium carbonates were primarily present as particulate forms in gastrointestinal fluids but enter the circulatory system in dissolved Ca(2+), although both types showed partial phase transformation to dicalcium phosphate dihydrate. Relatively low dissolution (about 4%), no remarkable protein-particle interaction, and the major particulate fate of calcium carbonate in vivo gastrointestinal fluids can explain its low oral absorption (about 4%) regardless of particle size. We conclude that calcium carbonate nanoparticles can act more

  4. Making Activated Carbon for Storing Gas

    NASA Technical Reports Server (NTRS)

    Wojtowicz, Marek A.; Serio, Michael A.; Suuberg, Eric M.

    2005-01-01

    Solid disks of microporous activated carbon, produced by a method that enables optimization of pore structure, have been investigated as means of storing gas (especially hydrogen for use as a fuel) at relatively low pressure through adsorption on pore surfaces. For hydrogen and other gases of practical interest, a narrow distribution of pore sizes <2 nm is preferable. The present method is a variant of a previously patented method of cyclic chemisorption and desorption in which a piece of carbon is alternately (1) heated to the lower of two elevated temperatures in air or other oxidizing gas, causing the formation of stable carbon/oxygen surface complexes; then (2) heated to the higher of the two elevated temperatures in flowing helium or other inert gas, causing the desorption of the surface complexes in the form of carbon monoxide. In the present method, pore structure is optimized partly by heating to a temperature of 1,100 C during carbonization. Another aspect of the method exploits the finding that for each gas-storage pressure, gas-storage capacity can be maximized by burning off a specific proportion (typically between 10 and 20 weight percent) of the carbon during the cyclic chemisorption/desorption process.

  5. Synthesis of activated carbon fiber from pyrolyzed cotton for adsorption of fume pollutants

    NASA Astrophysics Data System (ADS)

    Nuryantini, A. Y.; Rahayu, F.; Mahen, E. C. S.; Sawitri, A.; Nuryadin, B. W.

    2018-05-01

    In this study, we have synthesized and applied the activated carbon fibbers from pyrolyzed cotton to adsorp fume pollutants. The activated carbon fibbers from cotton were synthesized using an oven with simple heating method at low carbonization temperature. The cotton was successfully turned into carbon within four hours at carbonization temperature of 250°C. The reults showed that activation process using KOH and NaOH significantly affected the functional groups, morphology, diameter, and porosity of the activated carbon fibbers.

  6. Single-Particle Measurements of Midlatitude Black Carbon and Light-Scattering Aerosols from the Boundary Layer to the Lower Stratosphere

    NASA Technical Reports Server (NTRS)

    Schwartz, J. P.; Gao, R. S.; Fahey, D. W.; Thomson, D. S.; Watts, L. A.; Wilson, J. C.; Reeves, J. M.; Darbeheshti, M.; Baumgardner, D. G.; Kok, G. L.; hide

    2006-01-01

    A single-particle soot photometer (SP2) was flown on a NASA WB-57F high-altitude research aircraft in November 2004 from Houston, Texas. The SP2 uses laser-induced incandescence to detect individual black carbon (BC) particles in an air sample in the mass range of approx.3-300 fg (approx.0.15-0.7 microns volume equivalent diameter). Scattered light is used to size the remaining non-BC aerosols in the range of approx.0.17-0.7 microns diameter. We present profiles of both aerosol types from the boundary layer to the lower stratosphere from two midlatitude flights. Results for total aerosol amounts in the size range detected by the SP2 are in good agreement with typical particle spectrometer measurements in the same region. All ambient incandescing particles were identified as BC because their incandescence properties matched those of laboratory-generated BC aerosol. Approximately 40% of these BC particles showed evidence of internal mixing (e.g., coating). Throughout profiles between 5 and 18.7 km, BC particles were less than a few percent of total aerosol number, and black carbon aerosol (BCA) mass mixing ratio showed a constant gradient with altitude above 5 km. SP2 data was compared to results from the ECHAM4/MADE and LmDzT-INCA global aerosol models. The comparison will help resolve the important systematic differences in model aerosol processes that determine BCA loadings. Further intercomparisons of models and measurements as presented here will improve the accuracy of the radiative forcing contribution from BCA.

  7. The removal of chloramphenicol from water through adsorption on activated carbon

    NASA Astrophysics Data System (ADS)

    Lach, Joanna; Ociepa-Kubicka, Agnieszka

    2017-10-01

    The presented research investigated the removal of chloramphenicol from water solutions on selected activated carbon available in three grades with different porous structure and surface chemical composition. Two models of adsorption kinetics were examined, i.e. the pseudo-first order and the pseudo-second order models. For all examined cases, the results of tests with higher value of coefficient R2 were described by the equation for pseudo-second order kinetics. The adsorption kinetics was also investigated on the activated carbons modified with ozone. The measurements were taken from the solutions with pH values of 2 and 7. Chloramphenicol was the most efficiently adsorbed on the activated carbon F-300 from the solutions with pH=7, and on the activated carbon ROW 08 Supra from the solutions with pH=2. The adsorption of this antibiotic was in the majority of cases higher from the solutions with pH=2 than pH=7. The modification of the activated carbons with ozone enhanced their adsorption capacities for chloramphenicol. The adsorption is influenced by the modification method of activated carbon (i.e. the duration of ozonation of the activated carbon solution and the solution temperature). The results were described with the Freundlich and Langmuir adsorption isotherm equations. Both models well described the obtained results (high R2 values).

  8. Adsorption Properties of Lignin-derived Activated Carbon Fibers (LACF)

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Contescu, Cristian I.; Gallego, Nidia C.; Thibaud-Erkey, Catherine

    The object of this CRADA project between Oak Ridge National Laboratory (ORNL) and United Technologies Research Center (UTRC) is the characterization of lignin-derived activated carbon fibers (LACF) and determination of their adsorption properties for volatile organic compounds (VOC). Carbon fibers from lignin raw materials were manufactured at Oak Ridge National Laboratory (ORNL) using the technology previously developed at ORNL. These fibers were physically activated at ORNL using various activation conditions, and their surface area and pore-size distribution were characterized by gas adsorption. Based on these properties, ORNL did down-select five differently activated LACF materials that were delivered to UTRC formore » measurement of VOC adsorption properties. UTRC used standard techniques based on breakthrough curves to measure and determine the adsorption properties of indoor air pollutants (IAP) - namely formaldehyde and carbon dioxide - and to verify the extent of saturated fiber regenerability by thermal treatments. The results are summarized as follows: (1) ORNL demonstrated that physical activation of lignin-derived carbon fibers can be tailored to obtain LACF with surface areas and pore size distributions matching the properties of activated carbon fibers obtained from more expensive, fossil-fuel precursors; (2) UTRC investigated the LACF potential for use in air cleaning applications currently pursued by UTRC, such as building ventilation, and demonstrated their regenerability for CO2 and formaldehyde, (3) Both partners agree that LACF have potential for possible use in air cleaning applications.« less

  9. A brief review on activated carbon derived from agriculture by-product

    NASA Astrophysics Data System (ADS)

    Yahya, Mohd Adib; Mansor, Muhammad Humaidi; Zolkarnaini, Wan Amani Auji Wan; Rusli, Nurul Shahnim; Aminuddin, Anisah; Mohamad, Khalidah; Sabhan, Fatin Aina Mohamad; Atik, Arif Abdallah Aboubaker; Ozair, Lailatun Nazirah

    2018-06-01

    A brief review focusing on preparation of the activated carbon derived from agriculture by-products is presented. The physical and chemical activation of activated carbon were also reviewed. The effects of various parameters including types of activating agents, temperature, impregnation ratio, were also discussed. The applications of activated carbon from agricultural by products were briefly reviewed. It is provenly evident in this review, the relatively inexpensive and renewable resources of the agricultural waste were found to be effectively being converted into wealth materials.

  10. Coatings of black carbon in Tijuana, Mexico, during the CalMex Campaign

    NASA Astrophysics Data System (ADS)

    Takahama, S.; Russell, L. M.; Duran, R.; Subramanian, R.; Kok, G.

    2010-12-01

    Black carbon number and mass concentrations were measured by a single-particle soot photometer (SP2; by Droplet Measurement Technologies) in Tijuana, Mexico between May 15, 2010, and June 30, 2010, for the CalMex campaign. The measurement site, Parque Morelos, is a recreational area located in the Southeast region of Tijuana. The SP2 was equipped with 8-channels of signal detection that spans a wider range of sensitivity for incandescing and scattering measurements than traditional configurations. The campaign-average number concentration of incandescing particles was 280 #/cc, peaking during traffic activity in the mornings. Incandescing particles made up 50% of all particles (incandescing and purely scattering) detected by the SP2. The mode of the number size distribution estimated for black carbon, according to estimated mass-equivalent diameters, was approximately 100 nm or smaller. Temporal variations in estimated coating thicknesses for these black carbon particles are discussed together with co-located measurements of organic aerosol and inorganic salts.

  11. [Airborne particles in a multi-wall carbon nanotube production plant: observation of particle emission and personal exposure 1: Measurement in the packing process].

    PubMed

    Takaya, Mitsutoshi; Serita, Fumio; Ono-Ogasawara, Mariko; Shinohara, Yasushi; Saito, Hiroyuki; Koda, Shigeki

    2010-01-01

    In order to assess the exposure risks of multiwall carbon nanotubes (MWCNT) for packing workers, we carried out real-time monitoring in the two types of packing facilities of MWCNT, and exposure measurements for the packing workers. In the real-time monitoring, a scanning mobility particle sizer (SMPS) and an optical particle counter (OPC) were used to measure nanoscale particles and sub-micron/micron scale particles, respectively. A personal sampler with PM 4.0 was used to measure the personal exposures in the packing facilities. One of the packing facilities is manually operated and the other is automated. The concentrations of airborne dust in both facilities were almost the same as each other at 0.24 mg/m(3) (total dust). However, the results of personal exposure measurements were quite different between the two facilities. The exposure concentrations of workers in the manually and automated operations were 2.39/0.39 (total/respirable) mg/m(3) and 0.29/0.08 (total/respirable) mg/m(3), respectively. From the time series study, submicron scale particles were released into the workplace air when the CNT products were put into temporary container bags from a hopper and manually packed into shipping bags. However, the task-related nanoscale particle release was not observed. The manual packing operation is one of the "hot spots" in MWCNT production facilities, and automation brings much improvement to reduce MWCNT exposure.

  12. Sputtering yields of carbon based materials under high particle flux with low energy

    NASA Astrophysics Data System (ADS)

    Nakamura, K.; Nagase, A.; Dairaku, M.; Akiba, M.; Araki, M.; Okumura, Y.

    1995-04-01

    A new ion source which can produce high particle flux beams at low energies has been developed. This paper presents preliminary results on the sputtering yield of the carbon fiber reinforced composites (CFCs) measured with the new ion source. The sputtering yields of 1D and 2D CFCs, which are candidate materials for the divertor armour tiles, have been measured by the weight loss method under the hydrogen and deuterium particle fluxes of 2 ˜ 7 × 10 20/m 2 s at 50 ˜ 150 eV. Preferential sputtering of the matrix was observed on CFCs which included the matrix of 40 ˜ 60 w%. The energy dependence of the sputtering yields was weak. The sputtering yields of CFCs normally irradiated with deuterium beam were from 0.073 to 0.095, and were around three times larger than those with hydrogen beam.

  13. Production of activated carbons from waste tyres for low temperature NOx control.

    PubMed

    Al-Rahbi, Amal S; Williams, Paul T

    2016-03-01

    Waste tyres were pyrolysed in a bench scale reactor and the product chars were chemically activated with alkali chemical agents, KOH, K2CO3, NaOH and Na2CO3 to produce waste tyre derived activated carbons. The activated carbon products were then examined in terms of their ability to adsorb NOx (NO) at low temperature (25°C) from a simulated industrial process flue gas. This study investigates the influence of surface area and porosity of the carbons produced with the different alkali chemical activating agents on NO capture from the simulated flue gas. The influence of varying the chemical activation conditions on the porous texture and corresponding NO removal from the flue gas was studied. The activated carbon sorbents were characterized in relation to BET surface area, micropore and mesopore volumes and chemical composition. The highest NO removal efficiency for the waste tyre derived activated carbons was ∼75% which was obtained with the adsorbent treated with KOH which correlated with both the highest BET surface area and largest micropore volume. In contrast, the waste tyre derived activated carbons prepared using K2CO3, NaOH and Na2CO3 alkali activating agents appeared to have little influence on NO removal from the flue gases. The results suggest problematic waste tyres, have the potential to be converted to activated carbons with NOx removal efficiency comparable with conventionally produced carbons. Copyright © 2016 Elsevier Ltd. All rights reserved.

  14. Activated carbon derived from carbon residue from biomass gasification and its application for dye adsorption: Kinetics, isotherms and thermodynamic studies.

    PubMed

    Maneerung, Thawatchai; Liew, Johan; Dai, Yanjun; Kawi, Sibudjing; Chong, Clive; Wang, Chi-Hwa

    2016-01-01

    In this work, activated carbon (AC) as an effective and low-cost adsorbent was successfully prepared from carbon residue (or char, one of the by-products from woody biomass gasification) via physical activation. The surface area of char was significantly increased from 172.24 to 776.46m(2)/g after steam activation at 900°C. The obtained activated carbons were then employed for the adsorption of dye (Rhodamine B) and it was found that activated carbon obtained from steam activation exhibited the highest adsorption capability, which is mainly attributed to the higher surface area and the abundance of hydroxyl (-OH) and carboxyl (-COOH) groups on the activated carbon surface. Moreover, it was also found that the adsorption capability significantly increased under the basic condition, which can be attributed to the increased electrostatic interaction between the deprotonated (negatively charged) activated carbon and dye molecules. Furthermore, the equilibrium data were fitted into different adsorption isotherms and found to fit well with Langmuir model (indicating that dye molecules form monolayer coverage on activated carbon) with a maximum monolayer adsorption capability of 189.83mg/g, whereas the adsorption kinetics followed the pseudo-second-order kinetics. Copyright © 2015 Elsevier Ltd. All rights reserved.

  15. [Agglutination and phagocytosis of foreign abiotic particles by hemocytes of the blowely, Calliphora vicina in vivo. I. Dynamics of hemocyte activity during larval development].

    PubMed

    Kind, T V

    2005-01-01

    Three types of Calliphora larval hemocytes have been revealed to be involved in phagocytosis of abiotic foreign particles: thrombocytoids, larval plasmatocytes and plasmatocytes I. Thrombocytoids are the quickest to respond to the appearance of invaders. The onset of test particle entrapment by thrombocytoid cytoplasmic fragments was observed, depending on the larval age within 0.5-5.0 min after injection. Separated fragments were fused, forming strands or roundish agglutinates. Phagocytosis of carbon, carmine or Indian ink particles by larval plasmatocytes occurs far more lately, and no earlier than 20-30 min after injection. Plasmatocytes I are capable of foreign particles adhesion on their surface, with a subsequent morule formation, and of engulfing these particles. These two events start in different time periods: adhesion occurs in 5-10 min, while phagocytosis is observed in 1--3 h. The rate of test particle entrapment and stability of agglutinales clearly depends on the larval age. The most pronounced reaction of hemocytes to foreign particles may be observed by the end of feeding and crop emptying. The second, somewhat less expressed rise of activity occurs in mature larvae not long before the onset of pupariation. Diapause induction is accompanied by reducing activities of both plasmatocytes and thrompocytoids. The importance of different hemocyte types in cellular immune reaction of Calliphora vicina larvae, and co-ordination between plasmatocytes and thrombocytoids are discussed.

  16. Process effects on activated carbon with large specific surface area from corn cob.

    PubMed

    Cao, Qing; Xie, Ke-Chang; Lv, Yong-Kang; Bao, Wei-Ren

    2006-01-01

    The main factors that affect the large specific surface area (SSA) of the activated carbon from agricultural waste corn cobs were studied by chemically activated method with solution of KOH and soap which acted as surfactant. The experiment showed that not only the activation temperature, activation time and the mass ratio of KOH to the carbonized material, but also the activated methods using activator obviously influenced the SSA of activated carbon. The experimental operating conditions were as follows: the carbonized temperature being 450 degrees C and keeping time being 4 h using N2 as protective gas; the activation temperature being 850 degrees C and holding time being 1.2 h; the mass ratio of KOH to carbonized material being 4.0; the time of soaking carbonized material in the solution of KOH and soap being 30 min. Under the optimal conditions, the SSA of activated carbon from corn cobs reached 2700 m2/g. And the addition of the soap as surfactant may shorten the soaking time. The structure of the activated carbon prepared had narrow distribution of pore size and the micro-pores accounted for 78%. The advantages of the method described were easy and feasible.

  17. Collective dynamics of soft active particles

    NASA Astrophysics Data System (ADS)

    van Drongelen, Ruben; Pal, Anshuman; Goodrich, Carl P.; Idema, Timon

    2015-03-01

    We present a model of soft active particles that leads to a rich array of collective behavior found also in dense biological swarms of bacteria and other unicellular organisms. Our model uses only local interactions, such as Vicsek-type nearest-neighbor alignment, short-range repulsion, and a local boundary term. Changing the relative strength of these interactions leads to migrating swarms, rotating swarms, and jammed swarms, as well as swarms that exhibit run-and-tumble motion, alternating between migration and either rotating or jammed states. Interestingly, although a migrating swarm moves slower than an individual particle, the diffusion constant can be up to three orders of magnitude larger, suggesting that collective motion can be highly advantageous, for example, when searching for food.

  18. Exposure to fine particulate, black carbon, and particle number concentration in transportation microenvironments

    NASA Astrophysics Data System (ADS)

    Morales Betancourt, R.; Galvis, B.; Balachandran, S.; Ramos-Bonilla, J. P.; Sarmiento, O. L.; Gallo-Murcia, S. M.; Contreras, Y.

    2017-05-01

    This research determined intake dose of fine particulate matter (PM2.5), equivalent black carbon (eBC), and number of sub-micron particles (Np) for commuters in Bogotá, Colombia. Doses were estimated through measurements of exposure concentration, a surrogate of physical activity, as well as travel times and speeds. Impacts of travel mode, traffic load, and street configuration on dose and exposure were explored. Three road segments were selected because of their different traffic loads and composition, and dissimilar street configuration. The transport modes considered include active modes (walking and cycling) and motorized modes (bus, car, taxi, and motorcycle). Measurements were performed simultaneously in the available modes at each road segment. High average eBC concentrations were observed throughout the campaign, ranging from 20 to 120 μgm-3 . Commuters in motorized modes experienced significantly higher exposure concentrations than pedestrians and bicyclists. The highest average concentrations of PM2.5, eBC , and Np were measured inside the city's Bus Rapid Transit (BRT) system vehicles. Pedestrians and bicycle users in an open street configuration were exposed to the lowest average concentrations of PM2.5 and eBC , six times lower than those experienced by commuters using the BRT in the same street segment. Pedestrians experienced the highest particulate matter intake dose in the road segments studied, despite being exposed to lower concentrations than commuters in motorized modes. Average potential dose of PM2.5 and eBC per unit length traveled were nearly three times higher for pedestrians in a street canyon configuration compared to commuters in public transport. Slower travel speed and elevated inhalation rates dominate PM dose for pedestrians. The presence of dedicated bike lanes on sidewalks has a significant impact on reducing the exposure concentration for bicyclists compared to those riding in mixed traffic lanes. This study proposes a simple

  19. Cobalt- and iron-based nanoparticles hosted in SBA-15 mesoporous silica and activated carbon from biomass: Effect of modification procedure

    NASA Astrophysics Data System (ADS)

    Tsoncheva, Tanya; Genova, Izabela; Paneva, Daniela; Dimitrov, Momtchil; Tsyntsarski, Boyko; Velinov, Nicolay; Ivanova, Radostina; Issa, Gloria; Kovacheva, Daniela; Budinova, Temenujka; Mitov, Ivan; Petrov, Narzislav

    2015-10-01

    Ordered mesoporous silica of SBA-15 type and activated carbon, prepared from waste biomass (peach stones), are used as host matrix of nanosized iron and cobalt particles. The effect of preparation procedure on the state of loaded nanoparticles is in the focus of investigation. The obtained materials are characterized by Boehm method, low temperature physisorption of nitrogen, XRD, UV-Vis, FTIR, Mossbauer spectroscopy and temperature programmed reduction with hydrogen. The catalytic behaviour of the samples is tested in methanol decomposition. The dispersion, oxidative state and catalytic behaviour of loaded cobalt and iron nanoparticles are successfully tuned both by the nature of porous support and the metal precursor used during the samples preparation. Facile effect of active phase deposition from aqueous solution of nitrate precursors is assumed for activated carbon support. For the silica based materials the catalytic activity could be significantly improved when cobalt acetylacetonate is used during the modification. The complex effect of pore topology and surface functionality of different supports on the active phase formation is discussed.

  20. The effect of activated carbon support surface modification on characteristics of carbon nanospheres prepared by deposition precipitation of Fe-catalyst

    NASA Astrophysics Data System (ADS)

    Kristianto, H.; Arie, A. A.; Susanti, R. F.; Halim, M.; Lee, J. K.

    2016-11-01

    In this study the effect of activated carbon support modification to synthesis of CNSs was observed. Modification of activated carbon was done by using nitric acid. The effect of modification was analyzed from its FTIR spectra. The Fe catalysts were deposited on to the support by using urea deposition precipitation method at various initial catalysts concentration. CNSs was synthesized by utilizing cooking palm oil as renewable carbon source, and pyrolized at 700°C for 1 hour under nitrogen atmosphere. The products obtained then analyzed using SEM-EDS, TEM, XRD, and Raman spectroscopy. The modification of activated carbon support had increased the oxygen functional group. This increase resulted on increase of metal catalysts deposited on activated carbon surface. Peak of C (100) was observed, while ID/IG of samples were obtained around 0.9, which is commonly obtained for CNSs. High catalysts loading on modified activated carbon support caused decomposition of CNSs and formation carbon onion.

  1. Detailed Structural Analyses of KOH Activated Carbon from Waste Coffee Beans

    NASA Astrophysics Data System (ADS)

    Takahata, Tomokazu; Toda, Ikumi; Ono, Hiroki; Ohshio, Shigeo; Akasaka, Hiroki; Himeno, Syuji; Kokubu, Toshinori; Saitoh, Hidetoshi

    2009-11-01

    The relationship of the detailed structural change of KOH activated carbon and hydrogen storage ability was investigated in activated carbon materials fabricated from waste coffee beans. The specific surface area of porous carbon materials calculated from N2 adsorption isotherms stood at 2070 m2/g when the weight ratio of KOH to carbon materials was 5:1, and pore size was in the range of approximately 0.6 to 1.1 nm as micropores. In the structural analysis, X-ray diffraction analysis and Raman spectroscopy indicated structural change in these carbon materials through KOH activation. The order of the graphite structure changed to a smaller scale with this activation. It is theorized that specific surface area increased using micropores provided by carbon materials developed from the descent of the graphite structure. Hydrogen storage ability improved with these structural changes, and reached 0.6 wt % at 2070 m2/g. These results suggest that hydrogen storage ability is conferred by the chemical effect on graphite of carbon materials.

  2. In vitro immunotoxic and genotoxic activities of particles emitted from two different small-scale wood combustion appliances

    NASA Astrophysics Data System (ADS)

    Tapanainen, Maija; Jalava, Pasi I.; Mäki-Paakkanen, Jorma; Hakulinen, Pasi; Happo, Mikko S.; Lamberg, Heikki; Ruusunen, Jarno; Tissari, Jarkko; Nuutinen, Kati; Yli-Pirilä, Pasi; Hillamo, Risto; Salonen, Raimo O.; Jokiniemi, Jorma; Hirvonen, Maija-Riitta

    2011-12-01

    Residential wood combustion appliances emit large quantities of fine particles which are suspected to cause a substantial health burden worldwide. Wood combustion particles contain several potential health-damaging metals and carbon compounds such as polycyclic aromatic hydrocarbons (PAH), which may determine the toxic properties of the emitted particles. The aim of the present study was to characterize in vitro immunotoxicological and chemical properties of PM 1 ( Dp ≤ 1 μm) emitted from a pellet boiler and a conventional masonry heater. Mouse RAW264.7 macrophages were exposed for 24 h to different doses of the emission particles. Cytotoxicity, production of the proinflammatory cytokine TNF-α and the chemokine MIP-2, apoptosis and phases of the cell cycle as well as genotoxic activity were measured after the exposure. The type of wood combustion appliance had a significant effect on emissions and chemical composition of the particles. All the studied PM 1 samples induced cytotoxic, genotoxic and inflammatory responses in a dose-dependent manner. The particles emitted from the conventional masonry heater were 3-fold more potent inducers of programmed cell death and DNA damage than those emitted from the pellet boiler. Furthermore, the particulate samples that induced extensive DNA damage contained also large amounts of PAH compounds. Instead, significant differences between the studied appliances were not detected in measurements of inflammatory mediators, although the chemical composition of the combustion particles differed considerably from each other. In conclusion, the present results show that appliances representing different combustion technology have remarkable effects on physicochemical and associated toxicological and properties of wood combustion particles. The present data indicate that the particles emitted from incomplete combustion are toxicologically more potent than those emitted from more complete combustion processes.

  3. Catalytic ozonation of dimethyl phthalate over cerium supported on activated carbon.

    PubMed

    Li, Laisheng; Ye, Weiying; Zhang, Qiuyun; Sun, Fengqiang; Lu, Ping; Li, Xukai

    2009-10-15

    Cerium supported on activated carbon (Ce/AC), which was prepared by dipping method, was employed to degrade dimethyl phthalate (DMP) in water. The mineral matter present in the activated carbon positively contributes to its activity to enhance DMP ozonation process. A higher dipping Ce(NO(3))(3) concentration and calcination process increase its microporous volume and surface area, and decreases its exterior surface area. The catalytic activity reaches optimal when 0.2% (w/w) cerium is deposited on activated carbon. Ce/AC catalyst was characterized by XRD, SEM and BET. The presence of either activated carbon or Ce/AC catalyst considerably improves their degradation and mineralization in the ozonation of DMP. During the ozonation (50mg/h ozone flow rate) of a 30 mg/L DMP (initial pH 5.0) with the presence of Ce/AC catalyst, TOC removal rate reaches 68% at 60 min oxidation time, 48% using activated carbon as catalyst, only 22% with ozonation alone. The presence of tert-butanol (a well known OH radical scavenger) strongly inhibits DMP degradation by activated carbon or Ce/AC catalytic ozonation. TOC removal rate follows the second-order kinetics model well. In the ozonation of DMP with 50mg/h ozone flow rate, its mineralization rate constant with the presence of Ce/AC catalyst is 2.5 times higher than that of activated carbon, 7.5 times higher than that of O(3) alone. Ce/AC catalyst shows the better catalytic activity and stability based on 780 min sequential reaction in the ozonation of DMP. Ce/AC was a promising catalyst for ozonizing organic pollutants in the aqueous solution.

  4. Highly Crumpled All-Carbon Transistors for Brain Activity Recording.

    PubMed

    Yang, Long; Zhao, Yan; Xu, Wenjing; Shi, Enzheng; Wei, Wenjing; Li, Xinming; Cao, Anyuan; Cao, Yanping; Fang, Ying

    2017-01-11

    Neural probes based on graphene field-effect transistors have been demonstrated. Yet, the minimum detectable signal of graphene transistor-based probes is inversely proportional to the square root of the active graphene area. This fundamentally limits the scaling of graphene transistor-based neural probes for improved spatial resolution in brain activity recording. Here, we address this challenge using highly crumpled all-carbon transistors formed by compressing down to 16% of its initial area. All-carbon transistors, chemically synthesized by seamless integration of graphene channels and hybrid graphene/carbon nanotube electrodes, maintained structural integrity and stable electronic properties under large mechanical deformation, whereas stress-induced cracking and junction failure occurred in conventional graphene/metal transistors. Flexible, highly crumpled all-carbon transistors were further verified for in vivo recording of brain activity in rats. These results highlight the importance of advanced material and device design concepts to make improvements in neuroelectronics.

  5. Sorption of carbamazepine by commercial graphene oxides: a comparative study with granular activated carbon and multiwalled carbon nanotubes.

    PubMed

    Cai, Nan; Larese-Casanova, Philip

    2014-07-15

    Graphene nanosheet materials represent a potentially new high surface area sorbent for the treatment of endocrine disrupting compounds (EDCs) in water. However, sorption behavior has been reported only for laboratory graphene prepared by a laborious and hazardous graphite exfoliation process. A careful examination of commercially available, clean, high-volume produced graphene materials should reveal whether they are appropriate for sorbent technologies and which physicochemical properties most influence sorption performance. In this study, three commercially available graphene oxide powders of various particle sizes, specific surface areas, and surface chemistries were evaluated for their sorption performance using carbamazepine and nine other EDCs and were compared to that of conventional granular activated carbon (GAC) and multi-walled carbon nanotubes (MWCNTs). Sorption kinetics of carbamazepine on graphene oxide powders was rapid and reversible with alcohol washing, consistent with π-π interactions. The various sorption extents as described by Freundlich isotherms were best explained by available surface area, and only the highest surface area graphene oxide (771 m(2)/g) out-performed GAC and MWCNTs. Increasing pH caused more negative surface charge, a twofold decrease in sorption of anionic ibuprofen, a onefold increase in sorption of cationic atenolol, and no change for neutral carbamazepine, highlighting the role of electrostatic interactions. Copyright © 2014 Elsevier Inc. All rights reserved.

  6. Performances and nitrification properties of biological aerated filters with zeolite, ceramic particle and carbonate media.

    PubMed

    Qiu, Liping; Zhang, Shoubin; Wang, Guangwei; Du, Mao'an

    2010-10-01

    The performance and nitrification properties of three BAFs, with ceramic, zeolite and carbonate media, respectively, were investigated to evaluate the feasibility of employing these materials as biological aerated filter media. All three BAFs shown a promising COD and SS removal performance, while influent pH was 6.5-8.1, air-liquid ratio was 5:1 and HRT was 1.25-2.5 h, respectively. Ammonia removal in BAFs was inhibited when organic and ammonia nitrogen loading were increased, but promoted effectively with the increase pH value. Zeolite and carbonate were more suitable for nitrification than ceramic particle when influent pH below 6.5. It is feasible to employ these media in BAF and adequate bed volume has to be supplied to satisfy the requirement of removal COD, SS and ammonia nitrogen simultaneously in a biofilter. The carbonate with a strong buffer capacity is more suitable to treat the wastewater with variable or lower pH. Copyright 2010 Elsevier Ltd. All rights reserved.

  7. Facile solid-state synthesis of highly dispersed Cu nanospheres anchored on coal-based activated carbons as an efficient heterogeneous catalyst for the reduction of 4-nitrophenol

    NASA Astrophysics Data System (ADS)

    Wang, Shan; Gao, Shasha; Tang, Yakun; Wang, Lei; Jia, Dianzeng; Liu, Lang

    2018-04-01

    Coal-based activated carbons (AC) were acted as the support, Cu/AC catalysts were synthesized by a facile solid-state reaction combined with subsequent heat treatment. In Cu/AC composites, highly dispersed Cu nanospheres were anchored on AC. The catalytic activity for 4-nitrophenol (4-NP) was investigated, the effects of activation temperature and copper loading on the catalytic performance were studied. The catalysts exhibited very high catalytic activity and moderate chemical stability due to the unique characteristics of the particle-assembled nanostructures, the high surface area and the porous structure of coal-based AC and the good dispersion of metal particles. Design and preparation of non-noble metal composite catalysts provide a new direction for improving the added value of coal.

  8. A theory for the phase behavior of mixtures of active particles.

    PubMed

    Takatori, Sho C; Brady, John F

    2015-10-28

    Systems at equilibrium like molecular or colloidal suspensions have a well-defined thermal energy kBT that quantifies the particles' kinetic energy and gauges how "hot" or "cold" the system is. For systems far from equilibrium, such as active matter, it is unclear whether the concept of a "temperature" exists and whether self-propelled entities are capable of thermally equilibrating like passive Brownian suspensions. Here we develop a simple mechanical theory to study the phase behavior and "temperature" of a mixture of self-propelled particles. A mixture of active swimmers and passive Brownian particles is an ideal system for discovery of the temperature of active matter and the quantities that get shared upon particle collisions. We derive an explicit equation of state for the active/passive mixture to compute a phase diagram and to generalize thermodynamic concepts like the chemical potential and free energy for a mixture of nonequilibrium species. We find that different stability criteria predict in general different phase boundaries, facilitating considerations in simulations and experiments about which ensemble of variables are held fixed and varied.

  9. Polanyi Evaluation of Adsorptive Capacities of Commercial Activated Carbons

    NASA Technical Reports Server (NTRS)

    Monje, Oscar; Surma, Jan M.

    2017-01-01

    Commercial activated carbons from Calgon (207C and OVC) and Cabot Norit (RB2 and GCA 48) were evaluated for use in spacecraft trace contaminant control filters. The Polanyi potential plots of the activated carbons were compared using to those of Barnebey-Cheney Type BD, an untreated activated carbon with similar properties as the acid-treated Barnebey-Sutcliffe Type 3032 utilized in the TCCS. Their adsorptive capacities under dry conditions were measured in a closed loop system and the sorbents were ranked for their ability to remove common VOCs found in spacecraft cabin air. This comparison suggests that these sorbents can be ranked as GCA 48 207C, OVC RB2 for the compounds evaluated.

  10. Activated carbon from leather shaving wastes and its application in removal of toxic materials.

    PubMed

    Kantarli, Ismail Cem; Yanik, Jale

    2010-07-15

    In this study, utilization of a solid waste as raw material for activated carbon production was investigated. For this purpose, activated carbons were produced from chromium and vegetable tanned leather shaving wastes by physical and chemical activation methods. A detailed analysis of the surface properties of the activated carbons including acidity, total surface area, extent of microporosity and mesoporosity was presented. The activated carbon produced from vegetable tanned leather shaving waste produced has a higher surface area and micropore volume than the activated carbon produced from chromium tanned leather shaving waste. The potential application of activated carbons obtained from vegetable tanned shavings as adsorbent for removal of water pollutants have been checked for phenol, methylene blue, and Cr(VI). Adsorption capacities of activated carbons were found to be comparable to that of activated carbons derived from biomass. 2010 Elsevier B.V. All rights reserved.

  11. Catalytic activation of carbon–carbon bonds in cyclopentanones

    PubMed Central

    Xia, Ying; Lu, Gang; Liu, Peng; Dong, Guangbin

    2017-01-01

    In the chemical industry, molecules of interest are based primarily on carbon skeletons. When synthesizing such molecules, the activation of carbon–carbon single bonds (C–C bonds) in simple substrates is strategically important: it offers a way of disconnecting such inert bonds, forming more active linkages (for example, between carbon and a transition metal) and eventually producing more versatile scaffolds1–13. The challenge in achieving such activation is the kinetic inertness of C–C bonds and the relative weakness of newly formed carbon–metal bonds6,14. The most common tactic starts with a three- or four-membered carbon-ring system9–13, in which strain release provides a crucial thermodynamic driving force. However, broadly useful methods that are based on catalytic activation of unstrained C–C bonds have proven elusive, because the cleavage process is much less energetically favourable. Here we report a general approach to the catalytic activation of C–C bonds in simple cyclopentanones and some cyclohexanones. The key to our success is the combination of a rhodium pre-catalyst, an N-heterocyclic carbene ligand and an amino-pyridine co-catalyst. When an aryl group is present in the C3 position of cyclopentanone, the less strained C–C bond can be activated; this is followed by activation of a carbon–hydrogen bond in the aryl group, leading to efficient synthesis of functionalized α-tetralones—a common structural motif and versatile building block in organic synthesis. Furthermore, this method can substantially enhance the efficiency of the enantioselective synthesis of some natural products of terpenoids. Density functional theory calculations reveal a mechanism involving an intriguing rhodium-bridged bicyclic intermediate. PMID:27806379

  12. Scaling of cluster growth for coagulating active particles

    NASA Astrophysics Data System (ADS)

    Cremer, Peet; Löwen, Hartmut

    2014-02-01

    Cluster growth in a coagulating system of active particles (such as microswimmers in a solvent) is studied by theory and simulation. In contrast to passive systems, the net velocity of a cluster can have various scalings dependent on the propulsion mechanism and alignment of individual particles. Additionally, the persistence length of the cluster trajectory typically increases with size. As a consequence, a growing cluster collects neighboring particles in a very efficient way and thus amplifies its growth further. This results in unusual large growth exponents for the scaling of the cluster size with time and, for certain conditions, even leads to "explosive" cluster growth where the cluster becomes macroscopic in a finite amount of time.

  13. The Effect of CO2 Activation on the Electrochemical Performance of Coke-Based Activated Carbons for Supercapacitors.

    PubMed

    Lee, Hye-Min; Kim, Hong-Gun; An, Kay-Hyeok; Kim, Byung-Joo

    2015-11-01

    The present study developed electrode materials for supercapacitors by activating coke-based activated carbons with CO2. For the activation reaction, after setting the temperature at 1,000 degrees C, four types of activated carbons were produced, over an activation time of 0-90 minutes and with an interval of 30 minutes as the unit. The electrochemical performance of the activated carbons produced was evaluated to examine the effect of CO2 activation. The surface structure of the porous carbons activated through CO2 activation was observed using a scanning electron microscope (SEM). To determine the N2/77 K isothermal adsorption characteristics, the Brunauer-Emmett-Teller (BET) equation and the Barrett-Joyner-Halenda (BJH) equation were used to analyze the pore characteristics. In addition, charge and discharge tests and cyclic voltammetry (CV) were used to analyze the electrochemical characteristics of the changed pore structure. According to the results of the experiments, the N2 adsorption isotherm curves of the porous carbons produced belonged to Type IV in the International Union of Pore and Applied Chemistry (IUPAC) classification and consisted of micropores and mesopores, and, as the activation of CO2 progressed, micropores decreased and mesopores developed. The specific surface area of the porous carbons activated by CO2 was 1,090-1,180 m2/g and thus showed little change, but those of mesopores were 0.43-0.85 cm3/g, thus increasing considerably. In addition, when the electrochemical characteristics were analyzed, the specific capacity was confirmed to have increased from 13.9 F/g to 18.3 F/g. From these results, the pore characteristics of coke-based activated carbons changed considerably because of CO2 activation, and it was therefore possible to increase the electrochemical characteristics.

  14. Physical and chemical properties and adsorption type of activated carbon prepared from plum kernels by NaOH activation.

    PubMed

    Tseng, Ru-Ling

    2007-08-25

    Activated carbon was prepared from plum kernels by NaOH activation at six different NaOH/char ratios. The physical properties including the BET surface area, the total pore volume, the micropore ratio, the pore diameter, the burn-off, and the scanning electron microscope (SEM) observation as well as the chemical properties, namely elemental analysis and temperature programmed desorption (TPD), were measured. The results revealed a two-stage activation process: stage 1 activated carbons were obtained at NaOH/char ratios of 0-1, surface pyrolysis being the main reaction; stage 2 activated carbons were obtained at NaOH/char ratios of 2-4, etching and swelling being the main reactions. The physical properties of stage 2 activated carbons were similar, and specific area was from 1478 to 1887m(2)g(-1). The results of reaction mechanism of NaOH activation revealed that it was apparently because of the loss ratio of elements C, H, and O in the activated carbon, and the variations in the surface functional groups and the physical properties. The adsorption of the above activated carbons on phenol and three kinds of dyes (MB, BB1, and AB74) were used for an isotherm equilibrium adsorption study. The data fitted the Langmuir isotherm equation. Various kinds of adsorbents showed different adsorption types; separation factor (R(L)) was used to determine the level of favorability of the adsorption type. In this work, activated carbons prepared by NaOH activation were evaluated in terms of their physical properties, chemical properties, and adsorption type; and activated carbon PKN2 was found to have most application potential.

  15. Cloud condensation nuclei and ice nucleation activity of hydrophobic and hydrophilic soot particles.

    PubMed

    Koehler, Kirsten A; DeMott, Paul J; Kreidenweis, Sonia M; Popovicheva, Olga B; Petters, Markus D; Carrico, Christian M; Kireeva, Elena D; Khokhlova, Tatiana D; Shonija, Natalia K

    2009-09-28

    Cloud condensation nuclei (CCN) activity and ice nucleation behavior (for temperaturesparticle sub-types even within a narrow size cut. The heterogeneity could have resulted from both chemical and sizing differences, the latter attributable in part to particle non-sphericity. Neither GTS nor TS, hydrophobic particles distinguished only by the lower porosity and polarity of the GTS surface, showed CCN activity at or below water supersaturations required for wettable, insoluble particles (the Kelvin limit). TC1 soot particles, despite classification as hydrophilic, did not show CCN activity at or below the Kelvin limit. We attribute this result to the microporosity of this soot. In contrast, oxidized, non-porous, and hydrophilic TOS particles exhibited CCN activation at very near the Kelvin limit, with a small percentage of these particles CCN-active even at lower supersaturations. Due to containing a range of surface coverage of organic and inorganic hydrophilic and hygroscopic compounds, up to approximately 35% of hygroscopic AEC particles were active as CCN, with a small percentage of these particles CCN-active at lower supersaturations. In ice nucleation experiments below -40 degrees C, AEC particles nucleated ice near the expected condition for homogeneous freezing of water from aqueous solutions. In

  16. Application of activated carbon derived from scrap tires for adsorption of Rhodamine B.

    PubMed

    Li, Li; Liu, Shuangxi; Zhu, Tan

    2010-01-01

    Activated carbon derived from solid hazardous waste scrap tires was evaluated as a potential adsorbent for cationic dye removal. The adsorption process with respect to operating parameters was investigated to evaluate the adsorption characteristics of the activated pyrolytic tire char (APTC) for Rhodamine B (RhB). Systematic research including equilibrium, kinetics and thermodynamic studies was performed. The results showed that APTC was a potential adsorbent for RhB with a higher adsorption capacity than most adsorbents. Solution pH and temperature exert significant influence while ionic strength showed little effect on the adsorption process. The adsorption equilibrium data obey Langmuir isotherm and the kinetic data were well described by the pseudo second-order kinetic model. The adsorption process followed intra-particle diffusion model with more than one process affecting the adsorption process. Thermodynamic study confirmed that the adsorption was a physisorption process with spontaneous, endothermic and random characteristics.

  17. Magnetite impregnation effects on the sorbent properties of activated carbons and biochars.

    PubMed

    Han, Zhantao; Sani, Badruddeen; Mrozik, Wojciech; Obst, Martin; Beckingham, Barbara; Karapanagioti, Hrissi K; Werner, David

    2015-03-01

    This paper discusses the sorbent properties of magnetic activated carbons and biochars produced by wet impregnation with iron oxides. The sorbents had magnetic susceptibilities consistent with theoretical predictions for carbon-magnetite composites. The high BET surface areas of the activated carbons were preserved in the synthesis, and enhanced for one low surface area biochar by dissolving carbonates. Magnetization decreased the point of zero charge. Organic compound sorption correlated strongly with BET surface areas for the pristine and magnetized materials, while metal cation sorption did not show such a correlation. Strong sorption of the hydrophobic organic contaminant phenanthrene to the activated carbon or biochar surfaces was maintained following magnetite impregnation, while phenol sorption was diminished, probably due to enhanced carbon oxidation. Copper, zinc and lead sorption to the activated carbons and biochars was unchanged or slightly enhanced by the magnetization, and iron oxides also contributed to the composite metal sorption capacity. While a magnetic biochar with 219 ± 3.7 m(2)/g surface area nearly reached the very strong organic pollutant binding capacity of the two magnetic activated carbons, a magnetic biochar with 68 ± 2.8 m(2)/g surface area was the best metal sorbent. Magnetic biochars thus hold promise as more sustainable alternatives to coal-derived magnetic activated carbons. Copyright © 2014 Elsevier Ltd. All rights reserved.

  18. Characteristics of activated carbon resulted from pyrolysis of the oil palm fronds powder

    NASA Astrophysics Data System (ADS)

    Maulina, S.; Iriansyah, M.

    2018-02-01

    Activated carbon is the product of a charcoal impregnation process that has a higher absorption capacity and has more benefits than regular char. Therefore, this study aims to cultivate the powder of oil palm fronds into activated carbon that meets the requirements of Standard National Indonesia 06-3730-1995. To do so, the carbonization process of the powder of oil palm fronds was carried out using a pyrolysis reactor for 30 minutes at a temperature of 150 °C, 200 °C, and 250 °C in order to produce activated char. Then, the char was impregnated using Phosphoric Acid activator (H3PO4) for 24 hours. Characteristics of activated carbon indicate that the treatment of char by chemical activation of oil palm fronds powder has an effect on the properties of activated carbon. The activated carbons that has the highest absorption properties to Iodine (822.91 mg/g) were obtained from the impregnation process with 15% concentration of Phosphoric Acid (H3PO4) at pyrolysis temperature of 200 °C. Furthermore, the activation process resulted in activated carbon with water content of 8%, ash content of 4%, volatile matter 39%, and fixed carbon 75%, Iodine number 822.91 mg/g.

  19. INCREASED IL-8 AND IL-6 EXPRESSION IN HUMAN AIRWAY EPITHELIAL CELLS EXPOSED TO CARBON ULTRAFINE PARTICLES

    EPA Science Inventory

    INCREASED IL-6 AND IL-8 EXPRESSION IN HUMAN AIRWAY EPITHELIAL CELLS EXPOSED TO CARBON ULTRAFINE PARTICLES.
    R Silbajoris1, A G Lenz2, I Jaspers3, J M Samet1. 1NHEERL, USEPA, RTP, NC, USA; 2GSF-Institute for Inhalation Biology, Neuherberg, Germany; 3 CEMLB, UNC-CH, Chapel Hill, ...

  20. Focusing of active particles in a converging flow

    DOE PAGES

    Potomkin, Mykhailo; Kaiser, Andreas; Berlyand, Leonid; ...

    2017-10-20

    We consider active particles swimming in a convergent fluid flow in a trapezoid nozzle with no-slip walls. We use mathematical modeling to analyze trajectories of these particles inside the nozzle. By extensive Monte Carlo simulations, we show that trajectories are strongly affected by the background fluid flow and geometry of the nozzle leading to wall accumulation and upstream motion (rheotaxis). In particular, we describe the non-trivial focusing of active rods depending on physical and geometrical parameters. It is also established that the convergent component of the background flow leads to stability of both downstream and upstream swimming at the centerline.more » The stability of downstream swimming enhances focusing, and the stability of upstream swimming enables rheotaxis in the bulk.« less