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Sample records for activated carbon beds

  1. Adsorption dynamics of trichlorofluoromethane in activated carbon fiber beds.

    PubMed

    Zhang, Xiaoping; Zhao, Xin; Hu, Jiaqi; Wei, Chaohai; Bi, Hsiaotao T

    2011-02-28

    Adsorption on carbon fixed-beds is considered as an inexpensive and highly effective way for controlling chlorofluorocarbons (CFCs) emissions. In the present work, a dynamic model under constant-pattern wave conditions has been developed to predict the breakthrough behavior of trichlorofluoromethane (CFC-11) adsorption in a fixed bed packed with activated carbon fibers (ACFs). The adsorption of CFC-11 vapor onto viscose-based ACFs was performed in a fixed bed at different test conditions. The results showed that, in a deep bed (>120 mm), the analytical model based on the external mass transfer with the Langmuir isotherm could describe the adsorption dynamics well. The model parameters, the characteristic breakthrough time and the film mass-transfer coefficients are related to such operating parameters as the superficial gas velocity, feed concentration and bed height. It was found from the breakthrough dynamics that the mass transfer from the fluid phase to the fiber surface dominated the CFC-11 adsorption onto ACFs in fixed beds.

  2. Adsorption dynamics of trichlorofluoromethane in activated carbon fiber beds.

    PubMed

    Zhang, Xiaoping; Zhao, Xin; Hu, Jiaqi; Wei, Chaohai; Bi, Hsiaotao T

    2011-02-28

    Adsorption on carbon fixed-beds is considered as an inexpensive and highly effective way for controlling chlorofluorocarbons (CFCs) emissions. In the present work, a dynamic model under constant-pattern wave conditions has been developed to predict the breakthrough behavior of trichlorofluoromethane (CFC-11) adsorption in a fixed bed packed with activated carbon fibers (ACFs). The adsorption of CFC-11 vapor onto viscose-based ACFs was performed in a fixed bed at different test conditions. The results showed that, in a deep bed (>120 mm), the analytical model based on the external mass transfer with the Langmuir isotherm could describe the adsorption dynamics well. The model parameters, the characteristic breakthrough time and the film mass-transfer coefficients are related to such operating parameters as the superficial gas velocity, feed concentration and bed height. It was found from the breakthrough dynamics that the mass transfer from the fluid phase to the fiber surface dominated the CFC-11 adsorption onto ACFs in fixed beds. PMID:21216098

  3. Production of activated carbon from coconut shell char in a fluidized bed reactor

    SciTech Connect

    Sai, P.M.S.; Ahmed, J.; Krishnaiah, K.

    1997-09-01

    Activated carbon is produced from coconut shell char using steam or carbon dioxide as the reacting gas in a 100 mm diameter fluidized bed reactor. The effect of process parameters such as reaction time, fluidizing velocity, particle size, static bed height, temperature of activation, fluidizing medium, and solid raw material on activation is studied. The product is characterized by determination of iodine number and BET surface area. The product obtained in the fluidized bed reactor is much superior in quality to the activated carbons produced by conventional processes. Based on the experimental observations, the optimum values of process parameters are identified.

  4. Visualization of the exothermal VOC adsorption in a fixed-bed activated carbon adsorber.

    PubMed

    Le Cloirec, P; Pré, P; Delage, F; Giraudet, S

    2012-01-01

    Activated carbon fixed beds are classically used to remove volatile organic compounds (VOCs) present in gaseous emissions. In such use, an increase of local temperature due to exothermal adsorption has been reported; some accidental fires in the carbon bed due to the removal of high concentrations of ketones have been published. In this work, removal of VOCs was performed in a laboratory-scale pilot unit. In order to visualize the increase in local temperature, the adsorption front was tracked with a flame ionization detector and the thermal wave was simultaneously visualized with an infrared camera. In extreme conditions, fire in the adsorber and the combustion of activated carbon was achieved during ketone adsorption. Data have been extracted from these experiments, including local temperature, front velocity and carbon bed combustion conditions.

  5. Adsorption of organics from tar sand water by activated carbon in packed beds. Final report

    SciTech Connect

    Hines, A.L.; Pedram, E.O.

    1982-12-30

    The adsorption of TS-1S and TS-2C tar sand waters were studied at 278 and 298/sup 0/K on activated carbon in both batch and packed bed experiments. The isotherms were nonlinear over the entire liquid concentration ranges. Breakthrough curves were obtained in packed bed experiments as a function of bed lengths, particle size, and liquid velocity. A mechanistic approach was used to solve the mass transfer equations for the packed adsorber, the mass transfer coefficients and the rates of adsorption were calculated. Also the breakthrough curves were analyzed to establish the relative importance of the various individual mechanisms that contributed to the overall adsorption process.

  6. Breakthrough of methyethylketone and benzene vapors in activated carbon fiber beds.

    PubMed

    Huang, Zheng-Hong; Kang, Feiyu; Liang, Kai-Ming; Hao, Jiming

    2003-03-17

    The breakthrough of low concentration methyethylketone (MEK) and benzene vapors in beds packed with rayon-based activated carbon fiber (ACF) with different surface areas was investigated. The breakthrough characteristics depend on the properties of the ACF and the vapors, as well as on the adsorption conditions. The results of dynamic adsorption in an ACF bed were consistent with those of equilibrium adsorption by gravimetric methods. The breakthrough adsorption indicates that ACF, with an appropriate surface area, could be utilized in controlling volatile organic compounds (VOCs) in indoor air.

  7. Changes of the porous structure of activated carbons applied in a filter bed pilot operation.

    PubMed

    Gauden, P A; Szmechtig-Gauden, E; Rychlicki, G; Duber, S; Garbacz, J K; Buczkowski, R

    2006-03-15

    The paper investigates the changes in porosity (i.e., in the accessible adsorption capacity of carbonaceous adsorbents for pollutants during filter bed maturation) of three activated carbons applied in a filter bed pilot operation. The results of this investigation may help to reduce operating costs, increase granular activated carbon bed life, maximize the useful life of biofilters, and understand the mechanism of water purification by carbon adsorbents. The analysis of the pore structure was limited to the first year of service of the beds, since this was when the largest decrease in the available pore capacity occurred. Low-temperature nitrogen adsorption isotherms were used to evaluate the structural parameters and pore size distributions (PSDs) of carbon samples (virgin (reference) and mature adsorbents for different periods of water treatment) on the basis of the Nguyen and Do (ND) method and density functional theory (DFT). These results were compared with small-angle X-ray scattering (SAXS) investigations (PSDs calculated by Glatter's indirect transformation method (ITP)). The results show that in general, the ND and ITP methods lead to almost the same qualitative distribution curve behavior. Moreover, the enthalpy of immersion in water, mercury porosimetry, densities (true and apparent), and the analysis of ash are reported and compared to explain the decrease in adsorptive capacity of the carbons investigated. On the other hand, the efficacy of TOC (total organic carbon, i.e., a quantity describing the complex matrix of organic material present in natural waters) removal and the bacteria count were analyzed to explain the role of adsorption in the elimination of contaminants from water. Finally, a mechanism of organic matter removal was suggested on the basis of the above-mentioned experimental data and compared with mechanisms reported by other authors. PMID:16198363

  8. Mechanisms of granular activated carbon anaerobic fluidized-bed process for treating phenols wastewater.

    PubMed

    Lao, Shan-gen

    2002-01-01

    Granular activated carbon (GAC) anaerobic fluidized-bed reactor was applied to treating phenols wastewater. When influent phenol concentration was 1000 mg/L, volume loadings of phenol and CODCr were 0.39 kg/(m3.d) and 0.98 kg/(m3.d), their removal rates were 99.9% and 96.4% respectively. From analyzing above results, the main mechanisms of the process are that through fluidizing GAC, its adsorption is combined with biodegradation, both activities are brought into full play, and phenol in wastewater is effectively decomposed. Meanwhile problems concerning gas-liquid separation and medium plugging are well solved. PMID:11887310

  9. Dynamic adsorption of organic solvent vapors onto a packed bed of activated carbon cloth

    SciTech Connect

    Huang, C.C.; Lin, Y.C.; Lu, F.C.

    1999-02-01

    The adsorption behavior of organic compound vapors onto a packed bed of activated carbon cloth (ACC) has been investigated. Three types of ACCs have been employed: KF1500, FT200-20, and E-ACC. The volatile organic compounds (VOCs) used in this study are acetone, dichloromethane, acrylonitrile, and n-hexane. The operating parameters studied are temperature of adsorber, weight of ACC, relative humidity of fluid, inlet concentration of VOCs, and total volumetric flow rate of gas stream. A simple theoretical model, originally introduced by Yoon and Nelson, has been utilized to simulate the breakthrough curve of VOC vapor on an adsorption column packed with activated carbon cloth. A modified model is proposed to predict the adsorption behavior of an adsorber at different temperatures.

  10. Biological activated carbon fluidized-bed system to treat gasoline-contaminated groundwater

    SciTech Connect

    Voice, T.C.; Zhao, X.; Shi, J.; Hickey, R.F.

    1995-12-31

    An integrated biological granular activated carbon fluidized-bed reactor (GAC-FBR) and a biological fluidized-bed reactor (FBR) charged with nonactivated carbon were evaluated for treating groundwater contaminated with the gasoline constituents benzene, toluene, and xylenes (BTX). The systems were studied under several conditions including startup, steady-state, and step-load increase conditions. Development of bioactivity in the GAC-FBR was faster than in the FBR using a nonactivated carbon biomass carrier. Under two steady-state conditions, organic loading rates of 3 and 6 kg-chemical oxygen demand (COD)/m{sup 3}-day, BTX removal was similar in the two systems with more than 90% of applied BTX removed. The GAC-FBR produced superior effluent quality during step organic load rate (OLR) increases compared to the FBR. The results from an extremely high step OLR increase show the formation of partial oxidization products from the degradation of BTX. Significant adsorption capacity was still observed after the biofilm developed, although capacity gradually decreased over a 6-month period of operation to approximately 50% of its original value.

  11. Removal of CO2 in a multistage fluidized bed reactor by diethanol amine impregnated activated carbon.

    PubMed

    Das, Dipa; Samal, Debi Prasad; Meikap, Bhim C

    2016-07-28

    To mitigate the emission of carbon dioxide (CO2), we have developed and designed a four-stage fluidized bed reactor. There is a counter current exchange between solid adsorbent and gas flow. In this present investigation diethanol amine (DEA) impregnated activated carbon made from green coconut shell was used as adsorbent. This type of adsorbent not only adsorbs CO2 due to the presence of pore but also chemically reacts with CO2 and form secondary zwitterions. Sampling and analysis of CO2 was performed using Orsat apparatus. The effect of initial CO2 concentration, gas velocity, solid rate, weir height etc. on removal efficiency of CO2 have been investigated and presented. The percentage removal of CO2 has been found close to 80% under low gas flow rate (0.188 m/s), high solid flow rate (4.12 kg/h) and weir height of 50 mm. From this result it has been found out that multistage fluidized bed reactor may be a suitable equipment for removal of CO2 from flue gas. PMID:27163861

  12. Removal of CO2 in a multistage fluidized bed reactor by diethanol amine impregnated activated carbon.

    PubMed

    Das, Dipa; Samal, Debi Prasad; Meikap, Bhim C

    2016-07-28

    To mitigate the emission of carbon dioxide (CO2), we have developed and designed a four-stage fluidized bed reactor. There is a counter current exchange between solid adsorbent and gas flow. In this present investigation diethanol amine (DEA) impregnated activated carbon made from green coconut shell was used as adsorbent. This type of adsorbent not only adsorbs CO2 due to the presence of pore but also chemically reacts with CO2 and form secondary zwitterions. Sampling and analysis of CO2 was performed using Orsat apparatus. The effect of initial CO2 concentration, gas velocity, solid rate, weir height etc. on removal efficiency of CO2 have been investigated and presented. The percentage removal of CO2 has been found close to 80% under low gas flow rate (0.188 m/s), high solid flow rate (4.12 kg/h) and weir height of 50 mm. From this result it has been found out that multistage fluidized bed reactor may be a suitable equipment for removal of CO2 from flue gas.

  13. Corn stalks char from fast pyrolysis as precursor material for preparation of activated carbon in fluidized bed reactor.

    PubMed

    Wang, Zhiqi; Wu, Jingli; He, Tao; Wu, Jinhu

    2014-09-01

    Corn stalks char from fast pyrolysis was activated by physical and chemical activation process in a fluidized bed reactor. The structure and morphology of the carbons were characterized by N2 adsorption and SEM. Effects of activation time and activation agents on the structure of activation carbon were investigated. The physically activated carbons with CO2 have BET specific surface area up to 880 m(2)/g, and exhibit microporous structure. The chemically activated carbons with H3PO4 have BET specific surface area up to 600 m(2)/g, and exhibit mesoporous structure. The surface morphology shows that physically activated carbons exhibit fibrous like structure in nature with long ridges, resembling parallel lines. Whereas chemically activated carbons have cross-interconnected smooth open pores without the fibrous like structure.

  14. How to dose powdered activated carbon in deep bed filtration for efficient micropollutant removal.

    PubMed

    Altmann, Johannes; Ruhl, Aki S; Sauter, Daniel; Pohl, Julia; Jekel, Martin

    2015-07-01

    Direct addition of powdered activated carbon (PAC) to the inlet of a deep bed filter represents an energy- and space-saving option to remove organic micropollutants (OMPs) during advanced wastewater treatment or drinking water purification. In this lab-scale study, continuous dosing, preconditioning a filter with PAC and combinations thereof were investigated as possible dosing modes with respect to OMP adsorption efficiency. Continuous dosing resulted in decreasing effluent concentrations with increasing filter runtime due to adsorption onto accumulating PAC in the filter bed. Approximately constant removal levels were achieved at longer filter runtimes, which were mainly determined by the dose of fresh PAC, rather than the total PAC amount embedded. The highest effluent concentrations were observed during the initial filtration stage. Meanwhile, preconditioning led to complete OMP adsorption at the beginning of filtration and subsequent gradual OMP breakthrough. PAC distribution in the pumice filter was determined by the loss on ignition of PAC and pumice and was shown to be relevant for adsorption efficiency. Preconditioning with turbulent upflow led to a homogenous PAC distribution and improved OMP adsorption significantly. Combining partial preconditioning and continuous dosing led to low initial effluent concentrations, but ultimately achieved concentrations similar to filter runs without preconditioning. Furthermore, a dosing stop prior to the end of filtration was suitable to increase PAC efficiency without affecting overall OMP removals. PMID:25898248

  15. Bisphenol A removal by a Pseudomonas aeruginosa immobilized on granular activated carbon and operating in a fluidized bed reactor.

    PubMed

    Mita, Luigi; Grumiro, Laura; Rossi, Sergio; Bianco, Carmen; Defez, Roberto; Gallo, Pasquale; Mita, Damiano Gustavo; Diano, Nadia

    2015-06-30

    Serratia rubidiae, Pseudomonas aeruginosa and Escherichia coli K12 have been studied for their ability of Bisphenol A removal from aqueous systems and biofilm formation on activated granule carbon. Mathematical equations for biodegradation process have been elaborated and discussed. P. aeruginosa was found the best strain to be employed in the process of Bisphenol A removal. The yield in BPA removal of a P. aeruginosa biofilm grown on GAC and operating in a fluidized bed reactor has been evaluated. The results confirm the usefulness in using biological activated carbon (BAC process) to remove phenol compounds from aqueous systems.

  16. Use of activated carbon and natural zeolite as support materials, in an anaerobic fluidised bed reactor, for vinasse treatment.

    PubMed

    Fernández, N; Fdz-Polanco, F; Montalvo, S J; Toledano, D

    2001-01-01

    In Cuba, the alcohol distillation process from cane sugar molasses, produces a final waste (vinasse), with an enormous polluting potential and a high sulfate content. Applying the anaerobic technology, most of the biodegradable organic matter can turn into biogas, rich in methane but with concentrations of sulfide above 1%. The present work develops two experiences with anaerobic fluidized bed reactors (AFBR) using both Cuban raw material, activated carbon and natural zeolite, as support media, with the purpose of obtaining high organic matter removal rates and keeping sulfide and ammonium concentrations in the permissible ranges. The reactors were operated during 120 days, achieving an organic loading rate of 10 kg COD/m3 day, with COD removal above 70%, and a methane production of 2 L/d. The activated carbon and natural zeolite used support materials in anaerobic fluidized bed reactors, and showed good results of distillery waste removal. PMID:11575071

  17. Batch and fixed-bed adsorption of tartrazine azo-dye onto activated carbon prepared from apricot stones

    NASA Astrophysics Data System (ADS)

    Albroomi, H. I.; Elsayed, M. A.; Baraka, A.; Abdelmaged, M. A.

    2016-02-01

    This work describes the potential of utilizing prepared activated carbon from apricot stones as an efficient adsorbent material for tartrazine (TZ) azo-dye removal in a batch and dynamic adsorption system. The results revealed that activated carbons with well-developed surface area (774 m2/g) and pore volume (1.26 cm3/g) can be manufactured from apricot stones by H3PO4 activation. In batch experiments, effects of the parameters such as initial dye concentration and temperature on the removal of the dye were studied. Equilibrium was achieved in 120 min. Adsorption capacity was found to be dependent on the initial concentration of dye solution, and maximum adsorption was found to be 76 mg/g at 100 mg/L of TZ. The adsorption capacity at equilibrium (q e) increased from 22.6 to 76 mg/g with an increase in the initial dye concentrations from 25 to 100 mg/L. The thermodynamic parameters such as change in free energy (ΔG 0), enthalpy (ΔH 0) and entropy (ΔS 0) were determined and the positive value of (ΔH) 78.1 (K J mol-1) revealed that adsorption efficiency increased with an increase in the process temperature. In fixed-bed column experiments, the effect of selected operating parameters such as bed depth, flow rate and initial dye concentration on the adsorption capacity was evaluated. Increase in bed height of adsorption columns leads to an extension of breakthrough point as well as the exhaustion time of adsorbent. However, the maximum adsorption capacities decrease with increases of flow rate. The breakthrough data fitted well to bed depth service time and Thomas models with high coefficient of determination, R 2 ≥ 94.

  18. Aqueous phase adsorption of cephalexin by walnut shell-based activated carbon: A fixed-bed column study

    NASA Astrophysics Data System (ADS)

    Nazari, Ghadir; Abolghasemi, Hossein; Esmaieli, Mohamad; Sadeghi Pouya, Ehsan

    2016-07-01

    The walnut shell was used as a low cost adsorbent to produce activated carbon (AC) for the removal of cephalexin (CFX) from aqueous solution. A fixed-bed column adsorption was carried out using the walnut shell AC. The effect of various parameters like bed height (1.5, 2 and 2.5 cm), flow rate (4.5, 6 and 7.5 mL/min) and initial CFX concentration (50, 100 and 150 mg/L) on the breakthrough characteristics of the adsorption system was investigated at optimum pH 6.5. The highest bed capacity of 211.78 mg/g was obtained using 100 mg/L inlet drug concentration, 2 cm bed height and 4.5 mL/min flow rate. Three kinetic models, namely Adam's-Bohart, Thomas and Yoon-Nelson were applied for analysis of experimental data. The Thomas and Yoon-Nelson models were appropriate for walnut shell AC column design under various conditions. The experimental adsorption capacity values were fitted to the Bangham and intra-particle diffusion models in order to propose adsorption mechanisms. The effect of temperature on the degradation of CFX was also studied.

  19. Double-bed-type extraction needle packed with activated-carbon-based sorbents for very volatile organic compounds.

    PubMed

    Ueta, Ikuo; Samsudin, Emi Liana; Mizuguchi, Ayako; Takeuchi, Hayato; Shinki, Takumi; Kawakubo, Susumu; Saito, Yoshihiro

    2014-01-01

    A novel needle-type sample preparation device was developed for the determination of very volatile organic compounds (VVOCs) in gaseous samples by gas chromatography-mass spectrometry (GC-MS). Two types of activated-carbon-based sorbents, Carbopack X and a carbon molecular sieve (CMS), were investigated as the extraction medium. A double-bed-type extraction needle showed successful extraction and desorption performance for all investigated VVOCs, including acetaldehyde, isoprene, pentane, acetone, and ethanol. Sensitive and reliable determination of VVOCs was achieved by systematically optimizing several desorption conditions. In addition, the effects of sample humidity on the extraction and desorption of analytes were investigated with the needle-type extraction devices. Only the CMS packed extraction needle was adversely affected by sample humidity during the desorption process; on the other hand the double-bed-type extraction needle was unaffected by sample humidity. Finally, the developed double-bed-type extraction needle was successfully applied to the analysis of breath VVOCs of healthy subjects. PMID:24176747

  20. Continuous adsorption and biotransformation of micropollutants by granular activated carbon-bound laccase in a packed-bed enzyme reactor.

    PubMed

    Nguyen, Luong N; Hai, Faisal I; Dosseto, Anthony; Richardson, Christopher; Price, William E; Nghiem, Long D

    2016-06-01

    Laccase was immobilized on granular activated carbon (GAC) and the resulting GAC-bound laccase was used to degrade four micropollutants in a packed-bed column. Compared to the free enzyme, the immobilized laccase showed high residual activities over a broad range of pH and temperature. The GAC-bound laccase efficiently removed four micropollutants, namely, sulfamethoxazole, carbamazepine, diclofenac and bisphenol A, commonly detected in raw wastewater and wastewater-impacted water sources. Mass balance analysis showed that these micropollutants were enzymatically degraded following adsorption onto GAC. Higher degradation efficiency of micropollutants by the immobilized compared to free laccase was possibly due to better electron transfer between laccase and substrate molecules once they have adsorbed onto the GAC surface. Results here highlight the complementary effects of adsorption and enzymatic degradation on micropollutant removal by GAC-bound laccase. Indeed laccase-immobilized GAC outperformed regular GAC during continuous operation of packed-bed columns over two months (a throughput of 12,000 bed volumes). PMID:26803903

  1. Chemisorption of oxygen onto activated carbon can enhance the stability of biological perchlorate reduction in fixed bed biofilm reactors.

    PubMed

    Choi, Young Chul; Li, Xu; Raskin, Lutgarde; Morgenroth, Eberhard

    2008-07-01

    Fixed bed biofilm reactors with granular activated carbon (GAC) or glass beads as support media were used to evaluate the influence of short-term (12h) and long-term (23 days) increases of influent dissolved oxygen (DO) concentrations on biological perchlorate removal. The goal was to evaluate the extent by which chemisorption of oxygen to GAC can enhance the stability of biological perchlorate reduction. Baseline influent concentrations were 50 microg/L of perchlorate, 2 mg/L of acetate as C, and 1mg/L of DO. Perchlorate removal in the glass bead reactor seized immediately after increasing influent DO concentrations from 1 to 4 mg/L since glass beads have no sorptive capacity. In the biologically active carbon (BAC) reactor, chemisorption of oxygen to GAC removed a substantial fraction of the influent DO, and perchlorate removal was maintained during short-term increases of influent DO levels up to 8 mg/L. During long-term exposure to influent DO concentrations of 8.5mg/L, effluent perchlorate and DO concentrations increased slowly. Subsequent exposure of the BAC reactor bed to low DO concentrations partially regenerated the capacity for oxygen chemisorption. Microbial analyses indicated similar microbial communities in both reactors, which confirmed that the differences in reactor performance during dynamic loading conditions could be attributed to the sorptive properties of GAC. Using a sorptive biofilm support medium can enhance biological perchlorate removal under dynamic loading conditions.

  2. Supercritical CO2 desorption of activated carbon loaded with 2,2,3,3-tetrafluoro-1-propanol in a rotating packed bed.

    PubMed

    Tan, Chung-Sung; Lee, Pei-Lun

    2008-03-15

    Desorption of activated carbon loaded with 2,2,3,3-tetrafluoro-1-propanol (TFP) by supercritical carbon dioxide in a rotating packed bed was investigated in this study. The experimental data show that the time required to achieve complete desorption of TFP from activated carbon in a rotating packed bed was much lower than that in a static packed bed. The reduction of desorption time is attributed to the presence of centrifugal force. The supercritical CO2 desorption efficiency in a rotating packed bed was observed to increase with increasing rotation speed, pressure, and C02 flow rate. To enhance desorption efficiency, a smaller activated carbon particle size was suggested. At low operating pressures such as 8.96 and 11.72 MPa, a better desorption efficiency was found to occur at lower temperatures in a temperature range of 305-335 K. However, at high operating pressures such as 15.86 MPa, a temperature of 315 K was found to be more appropriate for desorption, as compared to other temperatures. Due to a reduction of packed bed volume and an increase in desorption efficiency, supercritical CO2 desorption in a rotating packed bed is suggested for recovering TFP from the exhaust gases. PMID:18409651

  3. Nanoporous activated carbon fluidized bed catalytic oxidations of aqueous o, p and m-cresols: kinetic and thermodynamic studies.

    PubMed

    Karthikeyan, S; Sekaran, G; Gupta, V K

    2013-07-01

    Nanoporous activated carbon prepared from rice husk through precarbonisation at 400 °C and phosphoric acid activation at 800 °C was used as fluidized bed in Fenton oxidation of the o, p and m-cresols in aqueous solution. The efficiencies of homogeneous Fenton oxidation, fluidized Fenton oxidation and aerobic biological oxidation systems for the removal of o, p and m-cresols in aqueous solution have been compared. The kinetic constants and the thermodynamic parameters for the homogeneous Fenton, heterogeneous Fenton and aerobic biological oxidations of o, p and m-cresols in synthetic wastewater were determined. The degradation of cresols in synthetic wastewater was confirmed using FT-IR, (1)H-NMR and UV-visible spectroscopy. PMID:23292221

  4. Three-component competitive adsorption model for fixed-bed and moving-bed granular activated carbon adsorbers. Part I. Model development.

    PubMed

    Schideman, Lance C; Mariñas, Benito J; Snoeyink, Vernon L; Campos, Carlos

    2006-11-01

    Heterogeneous natural organic matter (NOM) present in all natural waters impedes trace organic contaminant adsorption, and predictive modeling of granular activated carbon (GAC) adsorber performance is often compromised by inadequate accounting forthese competitive effects. Thus, a 3-component adsorption model, COMPSORB-GAC, is developed that separately tracks NOM adsorption and its competitive effects as a function of NOM surface loading. In this model, NOM is simplified into two fictive fractions with distinct competitive effects on trace compound adsorption: a smaller, strongly competing fraction that reduces equilibrium capacity and a larger pore-blocking fraction that reduces adsorption kinetics (both external film mass transfer and surface diffusion). COMPSORB-GAC tracks these two NOM fractions, along with the trace compound, and changes adsorption parameters according to the local surface loading of the two NOM fractions. Model parameters are allowed to vary both temporally and spatially to reflect differences in the NOM preloading conditions that occur in GAC columns. This dual-resistance model is based on homogeneous surface diffusion with external film mass-transfer limitations. The governing equations are expressed in a moving-grid finite-difference formulation to accommodate the modeling of spatially varying parameters and moving-bed reactors with counter-current adsorbent flow. A series of short-term adsorption tests with fresh and preloaded GAC is proposed to determine the necessary model input parameters. The accompanying manuscript demonstrates the parameterization procedure and verifies the model with experimental data. PMID:17144314

  5. Treatment of gas industry wastes using the biological granular activated carbon fluidized bed reactor process. Annual report, August 1994

    SciTech Connect

    Hickey, R.; Wagner, D.; Sunday, A.; Heine, B.; Rajan, R.

    1994-08-01

    The Granular Activated Carbon-Fluidized Bed Reactor (GAC-FBR) system is a high rate process that combines the advantages of biological and physical-chemical treatment in a single unit operation. The process is particularly well-suited to treatment of contaminants present in water and wastewater at relatively low concentrations. Process economics indicate the GAC-FBR can be extremely cost-effective compared to aqueous phase GAC adsorption and air stripping followed by vapor phase control. Accordingly, three field trials are scheduled for the next 18 months; one at a manufactured gas plant site (PAHs), one at a gas dehydration site (BTEX), and one to treat a chlorinated solvent (TCE) at a government installation.

  6. Evaluation of an integrated sponge--granular activated carbon fluidized bed bioreactor for treating primary treated sewage effluent.

    PubMed

    Xing, W; Ngo, H H; Guo, W S; Listowski, A; Cullum, P

    2011-05-01

    An integrated fluidized bed bioreactor (iFBBR) was designed to incorporate an aerobic sponge FBBR (ASB-FBBR) into an anoxic granular activated carbon FBBR (GAC-FBBR). This iFBBR was operated with and without adding a new starch based flocculant (NSBF) to treat synthetic primary treated sewage effluent (PTSE). The NSBF contains starch based cationic flocculants and trace nutrients. The results indicate that the iFBBR with NSBF addition could remove more than 93% dissolved organic carbon (DOC), 61% total nitrogen (T-N) and 60% total phosphorus (T-P) at just a very short hydraulic retention time of 50 min. The optimum frequency of adding NSBF to the iFFBR is four times per day. As a pretreatment to microfiltration, the iFFBR could increase 5L/m(2)h of critical flux thus reducing the membrane fouling. In addition, better microbial activity was also observed with high DO consumption (>66%) and specific oxygen uptake rate (>35 mg O(2)/g VSS h).

  7. Effect of granular activated carbon concentration on the content of organic matter and salt, influencing E. coli activity and survival in fluidized bed disinfection reactor.

    PubMed

    Racyte, Justina; Langenhoff, Alette A M; Ribeiro, Ana F M M R; Paulitsch-Fuchs, Astrid H; Bruning, Harry; Rijnaarts, Huub H M

    2014-10-01

    Granular activated carbon (GAC) is used in water treatment systems, typically to remove pollutants such as natural organic matter, volatile organic compounds, chlorine, taste, and odor. GAC is also used as a key component of a new technology that combines a fluidized bed reactor with radio frequency electric fields for disinfection. So far, the effects of GAC on bacteria in these fluidized bed reactors are unclear. This paper describes a systematic study of the physico-chemical changes in five microbial media compositions caused by different concentrations (23-350 g/L) of GAC, and the effects of these physico-chemical changes on the metabolic activity and survival of a model microorganism (Escherichia coli YMc10) in a fluidized bed reactor. The chemical adsorption taking place in suspensions with specific GAC changed nutritional, osmotic, and pH conditions in the investigated microbial media (LB, diluted LB, PBS, diluted PBS, and tap water), leading to a decay of the metabolic activity and survival of E. coli. Especially media that are poor in organic and mineral compounds (e.g., PBS) with suspended GAC showed a concentration decay of 3.5 Log CFU/mL E. coli after 6 h. Organic compounds depletion and severe pH variation were enhanced in the presence of higher GAC concentrations.

  8. Effect of granular activated carbon concentration on the content of organic matter and salt, influencing E. coli activity and survival in fluidized bed disinfection reactor.

    PubMed

    Racyte, Justina; Langenhoff, Alette A M; Ribeiro, Ana F M M R; Paulitsch-Fuchs, Astrid H; Bruning, Harry; Rijnaarts, Huub H M

    2014-10-01

    Granular activated carbon (GAC) is used in water treatment systems, typically to remove pollutants such as natural organic matter, volatile organic compounds, chlorine, taste, and odor. GAC is also used as a key component of a new technology that combines a fluidized bed reactor with radio frequency electric fields for disinfection. So far, the effects of GAC on bacteria in these fluidized bed reactors are unclear. This paper describes a systematic study of the physico-chemical changes in five microbial media compositions caused by different concentrations (23-350 g/L) of GAC, and the effects of these physico-chemical changes on the metabolic activity and survival of a model microorganism (Escherichia coli YMc10) in a fluidized bed reactor. The chemical adsorption taking place in suspensions with specific GAC changed nutritional, osmotic, and pH conditions in the investigated microbial media (LB, diluted LB, PBS, diluted PBS, and tap water), leading to a decay of the metabolic activity and survival of E. coli. Especially media that are poor in organic and mineral compounds (e.g., PBS) with suspended GAC showed a concentration decay of 3.5 Log CFU/mL E. coli after 6 h. Organic compounds depletion and severe pH variation were enhanced in the presence of higher GAC concentrations. PMID:24729067

  9. Upgrade of deep bed filtration with activated carbon dosage for compact micropollutant removal from wastewater in technical scale.

    PubMed

    Löwenberg, Jonas; Zenker, Armin; Krahnstöver, Thérèse; Boehler, Marc; Baggenstos, Martin; Koch, Gerhard; Wintgens, Thomas

    2016-05-01

    The removal of micropollutants from drinking and wastewater by powdered activated carbon (PAC) adsorption has received considerable attention in research over the past decade with various separation options having been investigated. With Switzerland as the first country in the world having adopted a new legislation, which forces about 100 wastewater treatment plants to be upgraded for the removal of organic micropollutants from municipal wastewater, the topic has reached practical relevance. In this study, the process combination of powdered activated carbon (PAC) adsorption and deep bed filtration (DBF) for advanced municipal wastewater treatment was investigated over an extended period exceeding one year of operation in technical scale. The study aimed to determine optimum process conditions to achieve sufficient micropollutant removal in agreement with the new Swiss Water Ordinance under most economic process design. It was shown that the addition of PAC and Fe(3+) as combined coagulation and flocculation agent improved effluent water quality with respect to dissolved organic pollutants as well as total suspended solids (TSS), turbidity and PO4-P concentration in comparison to a DBF operated without the addition of PAC and Fe(3+). Sufficient micropollutant (MP) removal of around 80% was achieved at PAC dosages of 10 mg/L revealing that PAC retained in the filter bed maintained considerable adsorption capacity. In the investigated process combination the contact reactor serves for adsorption as well as for flocculation and allowed for small hydraulic retention times of minimum 10 min while maintaining sufficient MP removal. The flocculation of two different PAC types was shown to be fully concluded after 10-15 min, which determined the flocculation reactor size while both PAC types proved suitable for the application in combination with DBF and showed no significant differences in MP removal. Finally, the capping of PAC dosage during rain water periods, which

  10. Recovery comparisons--hot nitrogen Vs steam regeneration of toxic dichloromethane from activated carbon beds in oil sands process.

    PubMed

    Ramalingam, Shivaji G; Pré, Pascaline; Giraudet, Sylvain; Le Coq, Laurence; Le Cloirec, Pierre; Baudouin, Olivier; Déchelotte, Stéphane

    2012-02-29

    The regeneration experiments of dichloromethane from activated carbon bed had been carried out by both hot nitrogen and steam to evaluate the regeneration performance and the operating cost of the regeneration step. Factorial Experimental Design (FED) tool had been implemented to optimize the temperature of nitrogen and the superficial velocity of the nitrogen to achieve maximum regeneration at an optimized operating cost. All the experimental results of adsorption step, hot nitrogen and steam regeneration step had been validated by the simulation model PROSIM. The average error percentage between the simulation and experiment based on the mass of adsorption of dichloromethane was 2.6%. The average error percentages between the simulations and experiments based on the mass of dichloromethane regenerated by nitrogen regeneration and steam regeneration were 3 and 12%, respectively. From the experiments, it had been shown that both the hot nitrogen and steam regeneration had regenerated 84% of dichloromethane. But the choice of hot nitrogen or steam regeneration depends on the regeneration time, operating costs, and purity of dichloromethane regenerated. A thorough investigation had been made about the advantages and limitations of both the hot nitrogen and steam regeneration of dichloromethane.

  11. A compact process for treating oilfield wastewater by combining hydrolysis acidification, moving bed biofilm, ozonation and biologically activated carbon techniques.

    PubMed

    Zheng, Tao

    2016-01-01

    A lab-scale hybrid system integrating a hybrid hydrolysis acidification (HA) reactor, a moving bed biofilm reactor (MBBR) and an ozonation-biologically activated carbon (O3-BAC) unit was used in the treatment of heavy oil wastewater with high chemical oxygen demand (COD) and low biodegradability. The effects of hydraulic retention time and ozonation time were investigated. The results show that under the optimal conditions, the effluent concentrations of COD, oil and ammonia were 48, 1.3 and 3.5 mg/L, respectively, corresponding to total removal efficiencies of 95.8%, 98.9% and 94.4%, respectively. The effluent could meet the grade I as required by the national discharge standard of China. The HA process remarkably improved the biodegradability of the wastewater, while the MBBR process played an important role in degrading COD. The ozonation process further enhanced the biodegradability of the MBBR effluent, and finally, deep treatment was completed in the BAC reactor. This work demonstrates that the hybrid HA/MBBR/O3-BAC system has the potential to be used for the treatment of high-strength oilfield wastewater.

  12. Coalesced chitosan activated carbon composite for batch and fixed-bed adsorption of cationic and anionic dyes.

    PubMed

    Auta, M; Hameed, B H

    2013-05-01

    A renewable waste tea activated carbon (WTAC) was coalesced with chitosan to form composite adsorbent used for waste water treatment. Adsorptive capacities of crosslinked chitosan beads (CCB) and its composite (WTAC-CCB) for Methylene blue dye (MB) and Acid blue 29 (AB29) were evaluated through batch and fixed-bed studies. Langmuir, Freundlich and Temkin adsorption isotherms were tested for the adsorption process and the experimental data were best fitted by Langmuir model and least by Freundlich model; the suitability of fitness was adjudged by the Chi-square (χ(2)) and Marquadt's percent standard deviation error functions. Judging by the values of χ(2), pseudo-second-order reaction model best described the adsorption process than pseudo-first-order kinetic model for MB/AB29 on both adsorbents. After five cycles of adsorbents desorption test, more than 50% WTAC-CCB adsorption efficiency was retained while CCB had <20% adsorption efficiency. The results of this study revealed that WTAC-CCB composite is a promising adsorbent for treatment of anionic and cationic dyes in effluent wastewaters.

  13. CARBON BED MERCURY EMISSIONS CONTROL FOR MIXED WASTE TREATMENT

    SciTech Connect

    Nick Soelberg; Joe Enneking

    2010-11-01

    Mercury has had various uses in nuclear fuel reprocessing and other nuclear processes, and so is often present in radioactive and mixed (both radioactive and hazardous according tohe Resource Conservation and Recovery Act) wastes. Depending on regulatory requirements, the mercury in the off-gas must be controlled with sometimes very high efficiencies. Compliance to the Hazardous Waste Combustor (HWC) Maximum Achievable Control Technology (MACT) standards can require off-gas mercury removal efficiencies up to 99.999% for thermally treating some mixed waste streams. Several test programs have demonstrated this level of off-gas mercury control using fixed beds of granular sulfur-impregnated activated carbon. Other results of these tests include: (a) The depth of the mercury control mass transfer zone was less than 15-30 cm for the operating conditions of these tests, (b) MERSORB® carbon can sorb Hg up to 19 wt% of the carbon mass, and (c) the spent carbon retained almost all (98 – 99.99%) of the Hg; but when even a small fraction of the total Hg dissolves, the spent carbon can fail the TCLP test when the spent carbon contains high Hg concentrations. Localized areas in a carbon bed that become heated through heat of adsorption, to temperatures where oxidation occurs, are referred to as “bed hot spots.” Carbon bed hot spots must be avoided in processes that treat radioactive and mixed waste. Key to carbon bed hot spot mitigation are (a) designing for sufficient gas velocity, for avoiding gas flow maldistribution, and for sufficient but not excessive bed depth, (b) monitoring and control of inlet gas flowrate, temperature, and composition, (c) monitoring and control of in-bed and bed outlet gas temperatures, and (d) most important, monitoring of bed outlet CO concentrations. An increase of CO levels in the off-gas downstream of the carbon bed to levels about 50-100 ppm higher than the inlet CO concentration indicate CO formation in the bed, caused by carbon bed

  14. Application of the biological granular activated carbon fluidized bed reactor process for gas industry waste treatment. Topical report, January 1991-December 1992

    SciTech Connect

    Wagner, D.; Sunday, A.; Hickey, R.F.

    1993-06-01

    The research and development work is focused on evaluating the applicability of using the biological granular activated carbon-fluidized bed reactor (GAC-FBR) for helping to solve gas industry waste treatment needs. The specific goals are to use and modify the GAC-FBR process, as needed, for (1) remediation of groundwater contaminated by gas industry operations, and (2) treatment of gas production and exploration waters.

  15. Combination of granular activated carbon adsorption and deep-bed filtration as a single advanced wastewater treatment step for organic micropollutant and phosphorus removal.

    PubMed

    Altmann, Johannes; Rehfeld, Daniel; Träder, Kai; Sperlich, Alexander; Jekel, Martin

    2016-04-01

    Adsorption onto granular activated carbon (GAC) is an established technology in water and advanced wastewater treatment for the removal of organic substances from the liquid phase. Besides adsorption, the removal of particulate matter by filtration and biodegradation of organic substances in GAC contactors has frequently been reported. The application of GAC as both adsorbent for organic micropollutant (OMP) removal and filter medium for solids retention in tertiary wastewater filtration represents an energy- and space saving option, but has rarely been considered because high dissolved organic carbon (DOC) and suspended solids concentrations in the influent of the GAC adsorber put a significant burden on this integrated treatment step and might result in frequent backwashing and unsatisfactory filtration efficiency. This pilot-scale study investigates the combination of GAC adsorption and deep-bed filtration with coagulation as a single advanced treatment step for simultaneous removal of OMPs and phosphorus from secondary effluent. GAC was assessed as upper filter layer in dual-media downflow filtration and as mono-media upflow filter with regard to filtration performance and OMP removal. Both filtration concepts effectively removed suspended solids and phosphorus, achieving effluent concentrations of 0.1 mg/L TP and 1 mg/L TSS, respectively. Analysis of grain size distribution and head loss within the filter bed showed that considerable head loss occurred in the topmost filter layer in downflow filtration, indicating that most particles do not penetrate deeply into the filter bed. Upflow filtration exhibited substantially lower head loss and effective utilization of the whole filter bed. Well-adsorbing OMPs (e.g. benzotriazole, carbamazepine) were removed by >80% up to throughputs of 8000-10,000 bed volumes (BV), whereas weakly to medium adsorbing OMPs (e.g. primidone, sulfamethoxazole) showed removals <80% at <5,000 BV. In addition, breakthrough behavior was

  16. Combination of granular activated carbon adsorption and deep-bed filtration as a single advanced wastewater treatment step for organic micropollutant and phosphorus removal.

    PubMed

    Altmann, Johannes; Rehfeld, Daniel; Träder, Kai; Sperlich, Alexander; Jekel, Martin

    2016-04-01

    Adsorption onto granular activated carbon (GAC) is an established technology in water and advanced wastewater treatment for the removal of organic substances from the liquid phase. Besides adsorption, the removal of particulate matter by filtration and biodegradation of organic substances in GAC contactors has frequently been reported. The application of GAC as both adsorbent for organic micropollutant (OMP) removal and filter medium for solids retention in tertiary wastewater filtration represents an energy- and space saving option, but has rarely been considered because high dissolved organic carbon (DOC) and suspended solids concentrations in the influent of the GAC adsorber put a significant burden on this integrated treatment step and might result in frequent backwashing and unsatisfactory filtration efficiency. This pilot-scale study investigates the combination of GAC adsorption and deep-bed filtration with coagulation as a single advanced treatment step for simultaneous removal of OMPs and phosphorus from secondary effluent. GAC was assessed as upper filter layer in dual-media downflow filtration and as mono-media upflow filter with regard to filtration performance and OMP removal. Both filtration concepts effectively removed suspended solids and phosphorus, achieving effluent concentrations of 0.1 mg/L TP and 1 mg/L TSS, respectively. Analysis of grain size distribution and head loss within the filter bed showed that considerable head loss occurred in the topmost filter layer in downflow filtration, indicating that most particles do not penetrate deeply into the filter bed. Upflow filtration exhibited substantially lower head loss and effective utilization of the whole filter bed. Well-adsorbing OMPs (e.g. benzotriazole, carbamazepine) were removed by >80% up to throughputs of 8000-10,000 bed volumes (BV), whereas weakly to medium adsorbing OMPs (e.g. primidone, sulfamethoxazole) showed removals <80% at <5,000 BV. In addition, breakthrough behavior was

  17. Treatment of naphthalene-2-sulfonic acid from tannery wastewater by a granular activated carbon fixed bed inoculated with bacterial isolates Arthrobacter globiformis and Comamonas testosteroni.

    PubMed

    Song, Zhi; Edwards, Suzanne R; Burns, Richard G

    2006-02-01

    The kinetics of naphthalene-2-sulfonic acid (2-NSA) adsorption by granular activated carbon (GAC) were measured and the relationships between adsorption, desorption, bioavailability and biodegradation assessed. The conventional Langmuir model fitted the experimental sorption isotherm data and introduced 2-NSA degrading bacteria, established on the surface of the GAC, did not interfere with adsorption. The potential value of GAC as a microbial support in the aerobic degradation of 2-NSA by Arthrobacter globiformis and Comamonas testosteroni was investigated. Using both virgin and microbially colonised GAC, adsorption removed 2-NSA from the liquid phase up to its saturation capacity of 140 mg/g GAC within 48 h. However, between 83.2% and 93.3% of the adsorbed 2-NSA was bioavailable to both bacterial species as a source of carbon for growth. In comparison to the non-inoculated GAC, the combination of rapid adsorption and biodegradation increased the amount (by 70-93%) of 2-NSA removal from the influent phase as well as the bed-life of the GAC (from 40 to >120 d). A microbially conditioned GAC fixed-bed reactor containing 15 g GAC removed 100% 2-NSA (100 mg/l) from tannery wastewater at an empty bed contact time of 22 min for a minimum of 120 d without the need for GAC reconditioning or replacement. This suggests that small volume GAC bioreactors could be used for tannery wastewater recycling.

  18. Production of bio-oil rich in acetic acid and phenol from fast pyrolysis of palm residues using a fluidized bed reactor: Influence of activated carbons.

    PubMed

    Jeong, Jae-Yong; Lee, Uen-Do; Chang, Won-Seok; Jeong, Soo-Hwa

    2016-11-01

    In this study, palm residues were pyrolyzed in a bench-scale (3kg/h) fast pyrolysis plant equipped with a fluidized bed reactor and bio-oil separation system for the production of bio-oil rich in acetic acid and phenol. Pyrolysis experiments were performed to investigate the effects of reaction temperature and the types and amounts of activated carbon on the bio-oil composition. The maximum bio-oil yield obtained was approximately 47wt% at a reaction temperature of 515°C. The main compounds produced from the bio-oils were acetic acid, hydroxyacetone, phenol, and phenolic compounds such as cresol, xylenol, and pyrocatechol. When coal-derived activated carbon was applied, the acetic acid and phenol yields in the bio-oils reached 21 and 19wt%, respectively. Finally, bio-oils rich in acetic acid and phenol could be produced separately by using an in situ bio-oil separation system and activated carbon as an additive. PMID:27501032

  19. Production of bio-oil rich in acetic acid and phenol from fast pyrolysis of palm residues using a fluidized bed reactor: Influence of activated carbons.

    PubMed

    Jeong, Jae-Yong; Lee, Uen-Do; Chang, Won-Seok; Jeong, Soo-Hwa

    2016-11-01

    In this study, palm residues were pyrolyzed in a bench-scale (3kg/h) fast pyrolysis plant equipped with a fluidized bed reactor and bio-oil separation system for the production of bio-oil rich in acetic acid and phenol. Pyrolysis experiments were performed to investigate the effects of reaction temperature and the types and amounts of activated carbon on the bio-oil composition. The maximum bio-oil yield obtained was approximately 47wt% at a reaction temperature of 515°C. The main compounds produced from the bio-oils were acetic acid, hydroxyacetone, phenol, and phenolic compounds such as cresol, xylenol, and pyrocatechol. When coal-derived activated carbon was applied, the acetic acid and phenol yields in the bio-oils reached 21 and 19wt%, respectively. Finally, bio-oils rich in acetic acid and phenol could be produced separately by using an in situ bio-oil separation system and activated carbon as an additive.

  20. Determining activated carbon performance

    SciTech Connect

    Naylor, W.F.; Rester, D.O.

    1995-07-01

    This article discusses the key elements involved in evaluating a system`s performance. Empty bed contact time (EBCT) is a term used to describe the length of time a liquid stream being treated is in contact with a granular activated carbon bed. The EBCT is the time required for a fluid to pass through the volume equivalent of the media bed, without the media being present. In a bed of granular activated carbon, the void volume or space between particles is usually about 45 percent. Therefore, the EBCT is about twice the true or actual time of contact between the fluid being treated and the GAC particles. The EBCT plays an important role in determining the effectiveness and longevity of granular activated carbon (GAC) used to treat liquids in a fixed-bed adsorber. Factors that influence and are influenced by EBCT, and their relationship to GAC performance in a treatment scheme include: adsorption, mass transfer zone, impurity concentration, adsorption affinity, flow rate and system design considerations.

  1. Effect of pH, empty bed contact time and hydraulic loading rate on lead removal by granular activated carbon columns

    SciTech Connect

    Reed, B.E.; Jamil, M.; Thomas, B.

    1996-07-01

    Batch and column studies were performed to determine the effect of pH, empty bed contact time (EBCT), and hydraulic loading rate (HLR) on lead removal by granular activated carbon (GAC) columns. Lead removal increased with increasing pH, and for the majority of the adsorbate:adsorbent ratios investigated, was 100% as pHs < pH{sub prec}. Column pH was extremely important to lead removal in GAC columns. A simple acid-base regeneration procedure was found to be effective in desorbing/resolubilizing the carbon-bound lead and raising the pH for the subsequent treatment run. Regeneration efficiencies were often less than 100%, but column performance was not adversely affected. For 1 mg/L lead, the optimum EBCT was between 6 and 7 minutes, Whereas for 10 mg/L lead it was less than 10 minutes. The effect of HLR (4.9 and 9.8 m/hr) on column performance was minimal for 1 mg/L lead, whereas at 10 mg/L lead column removal was slightly better at the higher HLR. Carbon usage rates were higher than those observed for wastewaters containing organic contaminants, especially at 10 mg/L lead. However, given the relatively simple regeneration scheme, the applicability of GAC columns for metal-bearing wastewaters appears to be technically feasible. 8 refs., 7 figs., 3 tabs.

  2. Avoiding Carbon Bed Hot Spots in Thermal Process Off-Gas Systems

    SciTech Connect

    Nick Soelberg; Joe Enneking

    2011-05-01

    Mercury has had various uses in nuclear fuel reprocessing and other nuclear processes, and so is often present in radioactive and mixed (radioactive and hazardous) wastes. Test programs performed in recent years have shown that mercury in off-gas streams from processes that treat radioactive wastes can be controlled using fixed beds of activated sulfur-impregnated carbon, to levels low enough to comply with air emission regulations such as the Hazardous Waste Combustor (HWC) Maximum Achievable Control Technology (MACT) standards. Carbon bed hot spots or fires have occurred several times during these tests, and also during a remediation of tanks that contained mixed waste. Hot spots occur when localized areas in a carbon bed become heated to temperatures where oxidation occurs. This heating typically occurs due to heat of absoption of gas species onto the carbon, but it can also be caused through external means such as external heaters used to heat the carbon bed vessel. Hot spots, if not promptly mitigated, can grow into bed fires. Carbon bed hot spots and fires must be avoided in processes that treat radioactive and mixed waste. Hot spots are detected by (a) monitoring in-bed and bed outlet gas temperatures, and (b) more important, monitoring of bed outlet gas CO concentrations. Hot spots are mitigated by (a) designing for appropriate in-bed gas velocity, for avoiding gas flow maldistribution, and for sufficient but not excessive bed depth, (b) appropriate monitoring and control of gas and bed temperatures and compositions, and (c) prompt implementation of corrective actions if bed hot spots are detected. Corrective actions must be implemented quickly if bed hot spots are detected, using a graded approach and sequence starting with corrective actions that are simple, quick, cause the least impact to the process, and are easiest to recover from.

  3. The Fate and Transport of the SiO2 Nanoparticles in a Granular Activated Carbon Bed and Their Impact on the Removal of VOCs

    EPA Science Inventory

    Adsorption isotherm, adsorption kinetics and column breakthrough experiments evaluating trichloroethylene (TCE) adsorption onto granular activated carbon (GAC) were conducted in the presence and absence of silica nanoparticles (SiO2 NPs). Zeta potential of the SiO

  4. TREATMENT OF CERCLA (COMPREHENSIVE ENVIRONMENTAL RESPONSE, COMPENSATION, AND LIABILITY ACT) LEACHATES BY CARBON-ASSISTED ANAEROBIC FLUIDIZED BEDS (Journal)

    EPA Science Inventory

    Two anaerobic granular activated carbon (GAC) expanded-bed bioreactors were tested as pretreatment units for the decontamination of hazardous leachates containing volatile and semivolatile synthetic organic chemicals (SOCs). The different characteristics of the two leachate feed...

  5. Removal of a wide range of emerging pollutants from wastewater treatment plant discharges by micro-grain activated carbon in fluidized bed as tertiary treatment at large pilot scale.

    PubMed

    Mailler, R; Gasperi, J; Coquet, Y; Buleté, A; Vulliet, E; Deshayes, S; Zedek, S; Mirande-Bret, C; Eudes, V; Bressy, A; Caupos, E; Moilleron, R; Chebbo, G; Rocher, V

    2016-01-15

    Among the solutions to reduce micropollutant discharges into the aquatic environment, activated carbon adsorption is a promising technique and a large scale pilot has been tested at the Seine Centre (240,000 m(3)/d - Paris, France) wastewater treatment plant (WWTP). While most of available works studied fixed bed or contact reactors with a separated separation step, this study assesses a new type of tertiary treatment based on a fluidized bed containing a high mass of activated carbon, continuously renewed. For the first time in the literature, micro-grain activated carbon (μGAC) was studied. The aims were (1) to determine the performances of fluidized bed operating with μCAG on both emerging micropollutants and conventional wastewater quality parameters, and (2) to compare its efficiency and applicability to wastewater to former results obtained with PAC. Thus, conventional wastewater quality parameters (n=11), pharmaceuticals and hormones (PPHs; n=62) and other emerging pollutants (n=57) have been monitored in μGAC configuration during 13 campaigns. A significant correlation has been established between dissolved organic carbon (DOC), PPHs and UV absorbance at 254 nm (UV-254) removals. This confirms that UV-254 could be used as a tertiary treatment performance indicator to monitor the process. This parameter allowed identifying that the removals of UV-254 and DOC reach a plateau from a μGAC retention time (SRT) of 90-100 days. The μGAC configuration substantially improves the overall quality of the WWTP discharges by reducing biological (38-45%) and chemical oxygen demands (21-48%), DOC (13-44%) and UV-254 (22-48%). In addition, total suspended solids (TSS) are retained by the μGAC bed and a biological activity (nitratation) leads to a total elimination of NO2(-). For micropollutants, PPHs have a good affinity for μGAC and high (>60%) or very high (>80%) removals are observed for most of the quantified compounds (n=22/32), i.e. atenolol (92

  6. Removal of a wide range of emerging pollutants from wastewater treatment plant discharges by micro-grain activated carbon in fluidized bed as tertiary treatment at large pilot scale.

    PubMed

    Mailler, R; Gasperi, J; Coquet, Y; Buleté, A; Vulliet, E; Deshayes, S; Zedek, S; Mirande-Bret, C; Eudes, V; Bressy, A; Caupos, E; Moilleron, R; Chebbo, G; Rocher, V

    2016-01-15

    Among the solutions to reduce micropollutant discharges into the aquatic environment, activated carbon adsorption is a promising technique and a large scale pilot has been tested at the Seine Centre (240,000 m(3)/d - Paris, France) wastewater treatment plant (WWTP). While most of available works studied fixed bed or contact reactors with a separated separation step, this study assesses a new type of tertiary treatment based on a fluidized bed containing a high mass of activated carbon, continuously renewed. For the first time in the literature, micro-grain activated carbon (μGAC) was studied. The aims were (1) to determine the performances of fluidized bed operating with μCAG on both emerging micropollutants and conventional wastewater quality parameters, and (2) to compare its efficiency and applicability to wastewater to former results obtained with PAC. Thus, conventional wastewater quality parameters (n=11), pharmaceuticals and hormones (PPHs; n=62) and other emerging pollutants (n=57) have been monitored in μGAC configuration during 13 campaigns. A significant correlation has been established between dissolved organic carbon (DOC), PPHs and UV absorbance at 254 nm (UV-254) removals. This confirms that UV-254 could be used as a tertiary treatment performance indicator to monitor the process. This parameter allowed identifying that the removals of UV-254 and DOC reach a plateau from a μGAC retention time (SRT) of 90-100 days. The μGAC configuration substantially improves the overall quality of the WWTP discharges by reducing biological (38-45%) and chemical oxygen demands (21-48%), DOC (13-44%) and UV-254 (22-48%). In addition, total suspended solids (TSS) are retained by the μGAC bed and a biological activity (nitratation) leads to a total elimination of NO2(-). For micropollutants, PPHs have a good affinity for μGAC and high (>60%) or very high (>80%) removals are observed for most of the quantified compounds (n=22/32), i.e. atenolol (92

  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. PMID:16376966

  8. Surface characterisation of carbon fibre recycled using fluidised bed

    NASA Astrophysics Data System (ADS)

    Jiang, G.; Pickering, S. J.; Walker, G. S.; Wong, K. H.; Rudd, C. D.

    2008-02-01

    X-ray photoelectron spectroscopy (XPS) was used to investigate the surface of carbon fibres recycled using a high-temperature fluidised bed. The interfacial shear strength of the recycled carbon fibres with epoxy resin was examined using a micro-droplet test. The corresponding as received carbon fibres were used as control samples. It was shown that the recycling process converted some of the surface hydroxyl groups into carbonyl and carboxylic groups due to the effect of heat in atmosphere of air. The overall O/C ratio was not changed significantly. The interfacial shear strength with epoxy resin was not affected by the change of surface oxygen composition. It was also shown that surface texture may play a dominant role in interfacial bonding performance.

  9. SPOUTED BED ELECTRODES (SBE) FOR DIRECT UTILIZATION OF CARBON IN FUEL CELLS

    SciTech Connect

    J.M. Calo

    2004-12-01

    This Phase I project was focused on an investigation of spouted bed particulate electrodes for the direct utilization of solid carbon in fuel cells. This approach involves the use of a circulating carbon particle/molten carbonate slurry in the cell that provides a few critical functions: it (1) fuels the cell continuously with entrained carbon particles; (2) brings particles to the anode surfaces hydrodynamically; (3) removes ash from the anode surfaces and the cell hydrodynamically; (4) provides a facile means of cell temperature control due to its large thermal capacitance; (5) provides for electrolyte maintenance and control in the electrode separator(s); and (6) can (potentially) improve carbon conversion rates by ''pre-activating'' carbon particle surfaces via formation of intermediate oxygen surface complexes in the bulk molten carbonate. The approach of this scoping project was twofold: (1) adaptation and application of a CFD code, originally developed to simulate particle circulation in spouted bed electrolytic reactors, to carbon particle circulation in DCFC systems; and (2) experimental investigation of the hydrodynamics of carbon slurry circulation in DCFC systems using simulated slurry mixtures. The CFD model results demonstrated that slurry recirculation can be used to hydrodynamically feed carbon particles to anode surfaces. Variations of internal configurations were investigated in order to explore effects on contacting. It was shown that good contacting with inclined surfaces could be achieved even when the particles are of the same density as the molten carbonate. The use of CO{sub 2} product gas from the fuel cell as a ''lift-gas'' to circulate the slurry was also investigated with the model. The results showed that this is an effective method of slurry circulation; it entrains carbon particles more effectively in the draft duct and produces a somewhat slower recirculation rate, and thus higher residence times on anode surfaces, and can be

  10. 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).

  11. Correlations describing the pressurized fluidized-bed hydroretorting carbon conversions of six Eastern oil shales

    SciTech Connect

    Rue, D.M.

    1991-12-31

    A set of correlations has been developed to describe the pressurized fluidized-bed hydroretorting carbon conversion of six Eastern oil shales. Laboratory scale fluidized bed and thermogravimetric data were used to relate hydroretorting conditions and organic carbon conversions to oil, gas, and residue. Conversions have been found to depend on temperature, hydrogen pressure, and residence time over the ranges studied of 750 to 865 K, 0 to 7 MPa H{sub 2}, and 0 to 30 minutes, respectively. Gas yield increases with increasing temperature but is independent of changes in hydrogen pressure. Oil yield increases with increasing hydrogen pressure and has different relationships to temperature for the various shales. A single mechanism has been used to describe the carbon conversions of Alabama and Tennessee Chattanooga, Indiana and Kentucky, New Albany, Michigan Antrim, and Ohio Cleveland shales under PFH conditions. The mechanism includes the simultaneous conversion of carbon to gas, oil, and an active carbon species which can form oil or remain as residue carbon. Yields are predicted over the temperature, hydrogen pressure, and residence time ranges used to PFH processing.

  12. Correlations describing the pressurized fluidized-bed hydroretorting carbon conversions of six Eastern oil shales

    SciTech Connect

    Rue, D.M.

    1991-01-01

    A set of correlations has been developed to describe the pressurized fluidized-bed hydroretorting carbon conversion of six Eastern oil shales. Laboratory scale fluidized bed and thermogravimetric data were used to relate hydroretorting conditions and organic carbon conversions to oil, gas, and residue. Conversions have been found to depend on temperature, hydrogen pressure, and residence time over the ranges studied of 750 to 865 K, 0 to 7 MPa H{sub 2}, and 0 to 30 minutes, respectively. Gas yield increases with increasing temperature but is independent of changes in hydrogen pressure. Oil yield increases with increasing hydrogen pressure and has different relationships to temperature for the various shales. A single mechanism has been used to describe the carbon conversions of Alabama and Tennessee Chattanooga, Indiana and Kentucky, New Albany, Michigan Antrim, and Ohio Cleveland shales under PFH conditions. The mechanism includes the simultaneous conversion of carbon to gas, oil, and an active carbon species which can form oil or remain as residue carbon. Yields are predicted over the temperature, hydrogen pressure, and residence time ranges used to PFH processing.

  13. [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.

  14. Carbon budgets of multispecies seagrass beds at Dongsha Island in the South China Sea.

    PubMed

    Huang, Yen-Hsun; Lee, Chen-Lu; Chung, Chia-Yun; Hsiao, Shu-Chuan; Lin, Hsing-Juh

    2015-05-01

    Biomass, production, consumption, and detrital export and decomposition of four dominant seagrass species were determined in tropical multispecies beds as a means of constructing carbon budgets. These processes varied among seagrass species. The living biomass held a high carbon stock. The leaf production of multispecies beds was also higher than that of monospecific beds. However, the sediment organic carbon stock was much lower than the global median stock, which was likely due to decomposition of most of the detritus and export to nearshore waters. Reliable measurements of decomposition and export are particularly needed to estimate the organic carbon storage rate.

  15. 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.

  16. Gasification behavior of carbon residue in bed solids of black liquor gasifier

    SciTech Connect

    Preto, Fernando; Zhang, Xiaojie; Wang, Jinsheng

    2008-07-15

    Steam gasification of carbon residue in bed solids of a low-temperature black liquor gasifier was studied using a thermogravimetric system at 3 bar. Complete gasification of the carbon residue, which remained unreactive at 600 C, was achieved in about 10 min as the temperature increased to 800 C. The rate of gasification and its temperature dependence were evaluated from the non-isothermal experiment results. Effects of particle size and adding H{sub 2} and CO to the gasification agent were also studied. The rate of steam gasification could be taken as zero order in carbon until 80% of carbon was gasified, and for the rest of the gasification process the rate appeared to be first order in carbon. The maximum rate of carbon conversion was around 0.003/s and the activation energy was estimated to be in the range of 230-300 kJ/mol. The particle size did not show significant effect on the rate of gasification. Hydrogen and carbon monoxide appeared to retard the onset of the gasification process. (author)

  17. Carbonate horizons, paleosols, and lake flooding cycles: Beds I and II of Olduvai Gorge, Tanzania.

    PubMed

    Bennett, Carys E; Marshall, Jim D; Stanistreet, Ian G

    2012-08-01

    This study documents the petrology and stable isotope geochemistry of carbonates from six horizons from Beds I and II of Olduvai Gorge, Tanzania. The studied succession, immediately below and above Tuff IF, consists of interbedded waxy and earthy claystones with discrete carbonate horizons and thin sandstones. The succession was deposited in response to repeated flooding and withdrawal of a saline-alkaline lake. The carbonates and their overlying disconformities are important because they help define the surfaces on which hominin activity took place and allow very high-resolution correlation of geographically separated levels of hominin exploitation. The range of different carbonates includes unambiguous land-surface and pedogenic features including calcified rootmat horizons, rhizocretions, and micritic nodules, together with less determinate sparry calcite nodules. Stellate nodules are interpreted as pseudomorphs after sulfate-roses. The carbonate nodules are synsedimentary features, truncated by fluvial and other erosional surfaces. The isotopic composition of the carbonates is variable with δ(18)O ranging from -7.0‰ to -4.3‰, and δ(13)C from -8.5‰ to -1.6‰. A covariant increase in δ(13)C and δ(18)O repeats in each carbonate horizon and in individual nodules (inner to outer layers): it reflects the evolution of synsedimentary groundwaters. At times of low lake level, the carbonates started to precipitate from meteoric waters with low isotopic values and continued to form as lake levels rose and the waters became increasingly saline. Some of the samples have a last-stage cement of strontium rich dolomite, which supports late-stage flooding by the saline-alkaline lake. Previous studies of carbonate horizons from Olduvai have interpreted carbon isotope values in terms of changes in C(3) and C(4) plants that colonized the land surface. This study demonstrates that in some instances the isotope values from carbonates deposited in these lake marginal

  18. Charcoal bed operation for optimal organic carbon removal

    SciTech Connect

    Merritt, C.M.; Scala, F.R.

    1995-05-01

    Historically, evaporation, reverse osmosis or charcoal-demineralizer systems have been used to remove impurities in liquid radwaste processing systems. At Nine Mile point, we recently replaced our evaporators with charcoal-demineralizer systems to purify floor drain water. A comparison of the evaporator to the charcoal-demineralizer system has shown that the charcoal-demineralizer system is more effective in organic carbon removal. We also show the performance data of the Granulated Activated Charcoal (GAC) vessel as a mechanical filter. Actual data showing that frequent backflushing and controlled flow rates through the GAC vessel dramatically increases Total Organic Carbon (TOC) removal efficiency. GAC vessel dramatically increases Total Organic Carbon (TOC) removal efficiency. Recommendations are provided for operating the GAC vessel to ensure optimal performance.

  19. Regulation of muscle sympathetic nerve activity after bed rest deconditioning

    NASA Technical Reports Server (NTRS)

    Pawelczyk, J. A.; Zuckerman, J. H.; Blomqvist, C. G.; Levine, B. D.

    2001-01-01

    Cardiovascular deconditioning reduces orthostatic tolerance. To determine whether changes in autonomic function might produce this effect, we developed stimulus-response curves relating limb vascular resistance, muscle sympathetic nerve activity (MSNA), and pulmonary capillary wedge pressure (PCWP) with seven subjects before and after 18 days of -6 degrees head-down bed rest. Both lower body negative pressure (LBNP; -15 and -30 mmHg) and rapid saline infusion (15 and 30 ml/kg body wt) were used to produce a wide variation in PCWP. Orthostatic tolerance was assessed with graded LBNP to presyncope. Bed rest reduced LBNP tolerance from 23.9 +/- 2.1 to 21.2 +/- 1.5 min, respectively (means +/- SE, P = 0.02). The MSNA-PCWP relationship was unchanged after bed rest, though at any stage of the LBNP protocol PCWP was lower, and MSNA was greater. Thus bed rest deconditioning produced hypovolemia, causing a shift in operating point on the stimulus-response curve. The relationship between limb vascular resistance and MSNA was not significantly altered after bed rest. We conclude that bed rest deconditioning does not alter reflex control of MSNA, but may produce orthostatic intolerance through a combination of hypovolemia and cardiac atrophy.

  20. Carbon monoxide formation and emissions during waste incineration in a grate-circulating fluidized bed incinerator.

    PubMed

    Yanguo Zhang; Qinghai Li; Aihong Meng; Changhe Chen

    2011-03-01

    This paper presents an experimental study of carbon monoxide (CO) formation and emissions in both grate drying bed incinerators and circulating fluidized bed (CFB) incinerators to simulate the two key parts of a combined grate and circulating fluidized bed (grate-CFB) incinerator in order to investigate pollutant emission control in municipal solid waste (MSW) combustion that occurs in a grate-CFB incinerator utilizing a patented technology. Polyvinyl chloride, polystyrene, kitchen waste, paper, textile, etc. were chosen to simulate the MSW. The effects of temperature, air staging, and moisture on the CO formation and emissions were analysed for both the grate drying bed combustion and the CFB combustion. In the grate drying bed, the low temperatures increased the carbon to CO conversion rate which also increased slightly with the moisture content. Industrial field tests in a commercial grate-CFB incinerator showed that the CO concentration at the grate drying bed exit was very high and decreased along furnace height. The carbon to CO conversion rates were 0-20% for the grate drying bed which exceeded the range of 0.8-16% measured in a grate drying bed exit of the commercial grate-CFB incinerator tests. In the commercial grate-CFB incinerator tests, at excess air ratios ranging from 1.5-2.0 or more, the CO emissions decreased to a low and stable level, whose corresponding carbon to CO conversion rates were far lower than 0-10%. The low CO emission is one of the factors enabling the polychlorinated dibenzodioxin/polychlorinated dibenzofuran emissions to satisfy the Chinese national regulations.

  1. Abnormal fingernail beds following carbon monoxide poisoning: a case report and review of the literature

    PubMed Central

    2014-01-01

    Introduction Carbon monoxide poisoning is a very common cause of death in accidental, suicidal, or homicidal cases throughout the world. Fingernail bed manifestation is reported in survivors of carbon monoxide poisoning. Case presentation A 40-year-old Caucasian woman was exposed to carbon monoxide when she was sleeping alone in her one-bedroom apartment; fortunately, the beeps from her First Alert combination smoke and carbon monoxide detector woke her and she was saved from any extensive health issues. The most indicative symptoms experienced were a severe headache, blurred vision, agitation, and confusion. Following contact with the Emergency Responses Services, she was promptly transferred to the hospital via ambulance and was treated with high-flow oxygen on the way. She was discharged from the emergency department on the same day, but carbon monoxide exposure had already had adverse effects on her fingernail beds. The fingernail tips were altered and appeared as if a bite had been taken out of their distal borders. The changes in the tips of her fingernails were significant, but they completely disappeared eight weeks later without any additional treatment. Conclusions Worldwide, carbon monoxide poisoning is a potentially lethal condition that is preventable with educational programs and installation of carbon monoxide detectors in the home setting. Exposure to carbon monoxide frequently goes unrecognized until it is too late and causes silent death. To the best of the authors’ knowledge, this is the first report in the literature of fingernail bed manifestations in a survivor of carbon monoxide poisoning. PMID:25073414

  2. Geomechanical risks in coal bed carbon dioxide sequestration

    SciTech Connect

    Myer, Larry R.

    2003-07-01

    The purpose of this report is to summarize and evaluate geomechanical factors which should be taken into account in assessing the risk of leakage of CO{sub 2} from coal bed sequestration projects. The various steps in developing such a project will generate stresses and displacements in the coal seam and the adjacent overburden. The question is whether these stresses and displacements will generate new leakage pathways by failure of the rock or slip on pre-existing discontinuities such as fractures and faults. In order to evaluate the geomechanical issues in CO{sub 2} sequestration in coal beds, it is necessary to review each step in the process of development of such a project and evaluate its geomechanical impact. A coal bed methane production/CO{sub 2} sequestration project will be developed in four steps: (1) Formation dewatering and methane production; (2) CO{sub 2} injection with accompanying methane production; (3) Possible CO{sub 2} injection for sequestration only; and The approach taken in this study was to review each step: Identify the geomechanical processes associated with it, and assess the risks that leakage would result from these processes.

  3. Deposition of carbonate mud beds within high-energy subtidal sand Dunes, Bahamas

    SciTech Connect

    Dill, R.F.; Steinen, R.P.

    1988-01-01

    Laminated, carbonate mud beds are being deposited in the interisland channels of the Exuma Cays in the Bahamas. They are associated with stromatolites and interbedded with ooid sands that form large migrating subtidal dunes on flood tidal deltas and bars. Currents up to 3 knots sweep in and out of the 4-8 m deep channels 3 hours out of every 6 hours, creating a high-energy bank margin environment not usually considered to be the site of mud-sized particle deposition. Mud deposits reach thicknesses of 1 m and have individual beds 2-5 cm thick. When exposed to flowing seawater, bed surfaces become encrusted with carbonate cement and algal mats. The white interior of mud beds between the crusts appears homogeneous, is soft, and has the consistency of ''tooth paste.'' Loose uncemented ooid sand is found above and below the mud beds, showing that both are occupying the same depositional environment. Rip-up clasts of the crusted mud beds, formed by scour of underlying sands, are carried throughout the channels and accumulate as a lag deposit within the troughs of migrating dunes. Some clasts are colonized by algal mats that trap ooid and skeletal sands forming stromatolite structures that can grow up to 2 m high.

  4. A 1-D Model of the 4 Bed Molecular Sieve of the Carbon Dioxide Removal Assembly

    NASA Technical Reports Server (NTRS)

    Coker, Robert; Knox, Jim

    2015-01-01

    Developments to improve system efficiency and reliability for water and carbon dioxide separation systems on crewed vehicles combine sub-scale systems testing and multi-physics simulations. This paper describes the development of COMSOL simulations in support of the Life Support Systems (LSS) project within NASA's Advanced Exploration Systems (AES) program. Specifically, we model the 4 Bed Molecular Sieve (4BMS) of the Carbon Dioxide Removal Assembly (CDRA) operating on the International Space Station (ISS).

  5. Industrial Scale Synthesis of Carbon Nanotubes Via Fluidized Bed Chemical Vapor Deposition: A Senior Design Project

    ERIC Educational Resources Information Center

    Smith, York R.; Fuchs, Alan; Meyyappan, M.

    2010-01-01

    Senior year chemical engineering students designed a process to produce 10 000 tonnes per annum of single wall carbon nanotubes (SWNT) and also conducted bench-top experiments to synthesize SWNTs via fluidized bed chemical vapor deposition techniques. This was an excellent pedagogical experience because it related to the type of real world design…

  6. Dewatering Peat With Activated Carbon

    NASA Technical Reports Server (NTRS)

    Rohatgi, N. K.

    1984-01-01

    Proposed process produces enough gas and carbon to sustain itself. In proposed process peat slurry is dewatered to approximately 40 percent moisture content by mixing slurry with activated carbon and filtering with solid/liquid separation techniques.

  7. Research on carbon content in fly ash from circulating fluidized bed boilers

    SciTech Connect

    Xianbin Xiao; Hairui Yang; Hai Zhang; Junfu Lu; Guangxi Yue

    2005-08-01

    The carbon content in the fly ash from most Chinese circulating fluidized bed (CFB) boilers is much higher than expected, which directly influences the combustion efficiency. In the present paper, carbon burnout was investigated in both field tests and laboratory experiments. The effect of coal property, operation condition, gas-solid mixing, char deactivation, residence time, and cyclone performance are analyzed seriatim based on a large amount of experimental results. A coal index is proposed to describe the coal rank, having a strong effect on the char burnout. Bad gas-solid mixing in the furnace is another important reason of the higher carbon content in the fly ash. Some chars in the fly ash are deactivated during combustion of large coal particles and have very low carbon reactivity. Several suggestions are made about design, operation, and modification to reduce the carbon content in the fly ash. 14 refs., 14 figs., 1 tab.

  8. Simultaneous carbon, nitrogen and phosphorous removal from municipal wastewater in a circulating fluidized bed bioreactor.

    PubMed

    Patel, Ajay; Zhu, Jesse; Nakhla, George

    2006-11-01

    In this study, the performance of the circulating fluidized bed bioreactor (CFBB) with anoxic and aerobic beds and employing lava rock as a carrier media for the simultaneous removal of carbon, nitrogen and phosphorus from municipal wastewater at an empty bed contact time (EBCT) of 0.82 h was discussed. The CFBB was operated without and with bioparticles' recirculation between the anoxic and aerobic bed for 260 and 110 d respectively. Without particles' recirculation, the CFBB was able to achieve carbon (C), total nitrogen (N) and phosphorous (P) removal efficiencies of 94%, 80% and 65% respectively, whereas with bioparticles' recirculation, 91%, 78% and 85% removals of C, N and P were achieved. The CFBB was operated at long sludge retention time (SRT) of 45-50 d, and achieved a sludge yield of 0.12-0.135 g VSS g COD(-1). A dynamic stress study of the CFBB was carried out at varying feed flow rates and influent ammonia concentrations to determine response to shock loadings. The CFBB responded favourably in terms of TSS and COD removal to quadrupling of the feed flow rate. However, nitrification was more sensitive to hydraulic shock loadings than to doubling of influent nitrogen loading. PMID:16762392

  9. Degradation of carbon tetrachloride in a semi-continuous packed-bed bioreactor

    SciTech Connect

    Levinson, W.E.; Korus, R.A.; Crawford, R.L.

    1995-12-31

    Pseudomonas sp. KC degrades carbon tetrachloride (CT) when grown under iron limited conditions. A packed-bed bioreactor was constructed out of glass and Teflon components and contained glass beads as a packing material. Total void volume of the reactor, including the pump reservoir, was approximately 300 mL. Media was recirculated through the reactor with a Teflon diaphragm pump and contained nitrate as terminal electron acceptor. After inoculation with KC and biofilm growth, the pump reservoir was replaced with fresh media and 3.0 mg/L CT was introduced to the reactor. When the initial CT had been degraded, 10% of the reactor volume was replaced with new media and CT was reintroduced. This process was repeated a second time. The initial degradation rate of the reactor increased from 75 {mu}g CT L{sup -1} hr{sup -1} for the first feeding to 109 {mu}g L{sup -1} hr{sup -1} for the third. A second reactor was packed with a Celite (diatomaceous earth) biocarrier and inoculated in a similar manner to the glass bead reactor. Degradation of CT in this reactor appeared to be suppressed, possibly due to the availability of iron to the bacteria from the biocarrier. While these experiments indicate it should be possible to design a bioreactor utilizing Pseudomonas sp. KC to degrade CT in contaminated water, the suppression of degradative activity by iron will require special precautions to be taken in reactor design.

  10. Postcombustion Capture of CO2 with CaO in a Circulating Fluidized Bed Carbonator

    NASA Astrophysics Data System (ADS)

    Alonso, M.; Rodriguez, N.; González, B.; Grasa, G.; Murillo, R.; Abanades, J. C.

    There is an emerging postcombustion capture technology that uses CaO to capture CO2 from combustion flue gases in a circulating fluidized bed reactor. This paper summarizes recent work conducted at CSIC to understand and develop this technology. The paper includes experimental results at conditions close to those expected in the real system, carried out in continuous mode in a 30kW test facility made up of two interconnected circulating fluidized bed reactors. In one of the reactors, CO2 is captured from the gas phase by the CaO continuously circulating from a calciner. In the second reactor, the CaCO3 formed in the carbonator is regenerated to CaO and CO2 by calcination. Modeling of the system at process level, at reactor level (in particular the CFB carbonator), and at particle level (decay in capture capability of CaO) is also outlined. The work carried out so far confirms that the carbonator reactors can be designed to attain capture efficiencies between 70-90%, operating at fluid dynamic conditions close to those present in circulating fluidized bed combustors.

  11. THE EFFECT OF ACTIVATED CARBON SURFACE MOISTURE ON LOW TEMPERATURE MERCURY ADSORPTION

    EPA Science Inventory

    Experiments with elemental mercury (Hg0) adsorption by activated carbons were performed using a bench-scale fixed-bed reactor at room temperature (27 degrees C) to determine the role of surface moisture in capturing Hg0. A bituminous-coal-based activated carbon (BPL) and an activ...

  12. 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.

  13. Impact of Sulfur Oxides on Mercury Capture by Activated Carbon

    SciTech Connect

    Presto, A.A.; Granite, E.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 ACI, 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. Separating proteins with activated carbon.

    PubMed

    Stone, Matthew T; Kozlov, Mikhail

    2014-07-15

    Activated carbon is applied to separate proteins based on differences in their size and effective charge. Three guidelines are suggested for the efficient separation of proteins with activated carbon. (1) Activated carbon can be used to efficiently remove smaller proteinaceous impurities from larger proteins. (2) Smaller proteinaceous impurities are most efficiently removed at a solution pH close to the impurity's isoelectric point, where they have a minimal effective charge. (3) The most efficient recovery of a small protein from activated carbon occurs at a solution pH further away from the protein's isoelectric point, where it is strongly charged. Studies measuring the binding capacities of individual polymers and proteins were used to develop these three guidelines, and they were then applied to the separation of several different protein mixtures. The ability of activated carbon to separate proteins was demonstrated to be broadly applicable with three different types of activated carbon by both static treatment and by flowing through a packed column of activated carbon. PMID:24898563

  15. Comparison of toluene adsorption among granular activated carbon and different types of activated carbon fibers (ACFs).

    PubMed

    Balanay, Jo Anne G; Crawford, Shaun A; Lungu, Claudiu T

    2011-10-01

    Activated carbon fiber (ACF) has been demonstrated to be a good adsorbent for the removal of organic vapors in air. Some ACF has a comparable or larger surface area and higher adsorption capacity when compared with granular activated carbon (GAC) commonly used in respiratory protection devices. ACF is an attractive alternative adsorbent to GAC because of its ease of handling, light weight, and decreasing cost. ACF may offer the potential for short-term respiratory protection for first responders and emergency personnel. This study compares the critical bed depths and adsorption capacities for toluene among GAC and ACF of different forms and surface areas. GAC and ACF in cloth (ACFC) and felt (ACFF) forms were challenged in stainless steel chambers with a constant concentration of 500 ppm toluene via conditioned air at 25°C, 50% RH, and constant airflow (7 L/min). Breakthrough data were obtained for each adsorbent using gas chromatography with flame ionization detector. Surface areas of each adsorbent were determined using a physisorption analyzer. Results showed that the critical bed depth of GAC is 275% higher than the average of ACFC but is 55% lower than the average of ACFF. Adsorption capacity of GAC (with a nominal surface area of 1800 m(2)/g) at 50% breakthrough is 25% higher than the average of ACF with surface area of 1000 m(2)/g, while the rest of ACF with surface area of 1500 m(2)/g and higher have 40% higher adsorption capacities than GAC. ACFC with higher surface area has the smallest critical bed depth and highest adsorption capacity, which makes it a good adsorbent for thinner and lighter respirators. We concluded that ACF has great potential for application in respiratory protection considering its higher adsorption capacity and lower critical bed depth in addition to its advantages over GAC, particularly for ACF with higher surface area.

  16. Multistage fluidized bed reactor performance characterization for adsorption of carbon dioxide

    SciTech Connect

    Roy, S.; Mohanty, C.R.; Meikap, B.C.

    2009-12-15

    Carbon dioxide and its different compounds are generated as primary greenhouse gases from the flue gases of coal-fired thermal power plants, boilers, and other stationary combustion processes. This greenhouse gas causes global warming after being emitted to the environment. To deal with this problem, a new dry scrubbing process was tested in this study. A three-stage countercurrent fluidized bed adsorber was developed, designed, and fabricated. It was used as a removal apparatus and operated in a continuous regime for the two-phase system. The height of each stage was 0.30 m, and the inner diameter was 0.10 m. The paper presents the removal of CO{sub 2} from gas mixtures by chemical sorption on porous granular calcium oxide particles in the reactor at ambient temperature. The advantages of a multistage fluidized bed reactor for high mass transfer and high gas-solid contact can enhance the removal of the gas when using a dry method. The effects of the operating parameters such as sorbent, superficial gas velocity, and the Weir height on CO{sub 2} removal efficiency in the multistage fluidized bed were investigated. The results indicate that the removal efficiency of the carbon dioxide was around 71% at a high solid flow rate corresponding to lower gas velocity at room temperature. In comparison with wet scrubbers, this dry process appears to have lower cost, less complicated configuration, and simpler disposal of used sorbent. The results in this study assume importance from the perspective of use of a multistage fluidized bed adsorber for control of gaseous pollutants at high temperature.

  17. EFFECT OF MOISTURE ON ADSORPTION OF ELEMENTAL MERCURY BY ACTIVATED CARBON

    EPA Science Inventory

    The paper discusses experiments using activated carbon to capture elemental mercury (Hgo), and a bench-scale dixed-bed reactor and a flow reactor to determine the role of surface moisture in Hgo adsorption. Three activated-carbon samples, with different pore structure and ash co...

  18. Enhanced removal of sulfonamide antibiotics by KOH-activated anthracite coal: Batch and fixed-bed studies.

    PubMed

    Zuo, Linzi; Ai, Jing; Fu, Heyun; Chen, Wei; Zheng, Shourong; Xu, Zhaoyi; Zhu, Dongqiang

    2016-04-01

    The presence of sulfonamide antibiotics in aquatic environments poses potential risks to human health and ecosystems. In the present study, a highly porous activated carbon was prepared by KOH activation of an anthracite coal (Anth-KOH), and its adsorption properties toward two sulfonamides (sulfamethoxazole and sulfapyridine) and three smaller-sized monoaromatics (phenol, 4-nitrophenol and 1,3-dinitrobenzene) were examined in both batch and fixed-bed adsorption experiments to probe the interplay between adsorbate molecular size and adsorbent pore structure. A commercial powder microporous activated carbon (PAC) and a commercial mesoporous carbon (CMK-3) possessing distinct pore properties were included as comparative adsorbents. Among the three adsorbents Anth-KOH exhibited the largest adsorption capacities for all test adsorbates (especially the two sulfonamides) in both batch mode and fixed-bed mode. After being normalized by the adsorbent surface area, the batch adsorption isotherms of sulfonamides on PAC and Anth-KOH were displaced upward relative to the isotherms on CMK-3, likely due to the micropore-filling effect facilitated by the microporosity of adsorbents. In the fixed-bed mode, the surface area-normalized adsorption capacities of Anth-KOH for sulfonamides were close to that of CMK-3, and higher than that of PAC. The irregular, closed micropores of PAC might impede the diffusion of the relatively large-sized sulfonamide molecules and in turn led to lowered fixed-bed adsorption capacities. The overall superior adsorption of sulfonamides on Anth-KOH can be attributed to its large specific surface area (2514 m(2)/g), high pore volume (1.23 cm(3)/g) and large micropore sizes (centered at 2.0 nm). These findings imply that KOH-activated anthracite coal is a promising adsorbent for the removal of sulfonamide antibiotics from aqueous solution.

  19. Treatment of activated carbon to enhance catalytic activity for reduction of nitric oxide with ammonia

    SciTech Connect

    Ku, B.J.; Rhee, H.K. . Dept. of Chemical Engineering); Lee, J.K.; Park, D. )

    1994-11-01

    Catalytic activity of activated carbon treated with various techniques was examined in a fixed bed reactor for the reduction of nitric oxide with ammonia at 150 C. Activated carbon derived from coconut shell impregnated with an aqueous solution of ammonium sulfate, further treated with sulfuric acid, dried at 120 C, and then heated in an inert gas stream at 400 C, showed the highest catalytic activity within the range of experimental conditions. The enhancement of catalytic activity of modified activated carbon could be attributed to the increase in the amount of oxygen function groups which increased the adsorption site for ammonia. Catalytic activity of activated carbons depended on the surface area and the oxygen content as well.

  20. Intrashelf basins: A geologic model for source-bed and reservoir facies deposition within carbonate shelves

    SciTech Connect

    Grover, G. Jr. )

    1993-09-01

    Intrashelf basins (moats, inshore basins, shelf basins, differentiated shelf, and deep-water lagoons of others) are depressions of varying sizes and shapes that occur within tectonically passive and regionally extensive carbonate shelves. Intrashelf basins grade laterally and downdip (seaward) into shallow-water carbonates of the regional shelf, are separated from the open marine basin by the shelf margin, and are largely filled by fine-grained subtidal sediments having attributes of shallow- and deeper water sedimentation. These basins are commonly fringed or overlain by carbonate sands, reefs, or buildups. These facies may mimic those that occur along the regional shelf margin, and they can have trends that are at a high angle to that of the regional shelf. Intrashelf basins are not intracratonic basins. The history of most intrashelf basins is a few million to a few tens of million of years. Examples of intrashelf basins are known throughout the Phanerozoic; the southern portion of the Holocene Belize shelf is a modern example of an intrashelf basin. Two types of intrashelf basins are recognized. Coastal basins pass updip into coastal clastics of the craton with the basin primarily filled by fine clastics. Shelf basins occur on the outer part of the shelf, are surrounded by shallow-water carbonate facies, and are filled by peloidal lime mud, pelagics, and argillaceous carbonates. Intrashelf basins are commonly the site of organic-rich, source-bed deposition, resulting in the close proximity of source beds and reservoir facies that may fringe or overlie the basin. Examples of hydrocarbon-charged reservoirs that were sourced by an intrashelf basin include the Miocene Bombay High field, offshore India; the giant Jurassic (Arab-D) and Cretaceous (Shuaiba) reservoirs of the Arabian Shelf; the Lower Cretaceous Sunniland trend, South Florida basin; and the Permian-Pennsylvanian reservoirs surrounding the Tatum basin in southeastern New Mexico.

  1. Activated carbon to the rescue

    SciTech Connect

    Sen, S.

    1996-03-01

    This article describes the response to pipeline spill of ethylene dichloride (EDC) on the property of an oil company. Activated carbon cleanup proceedure was used. During delivery, changeout, transport, storage, thermal reactivation, and return delivery to the site, the carbon never came into direct contact with operating personnel or the atmosphere. More than 10,000 tones of dredge soil and 50 million gallons of surface water were processed during the emergency response.

  2. DEVELOPMENT OF ACTIVATED CARBONS FROM COAL COMBUSTION BY-PRODUCTS

    SciTech Connect

    Harold H. Schobert; M. Mercedes Maroto-Valer; Zhe Lu

    2003-09-30

    The increasing role of coal as a source of energy in the 21st century will demand environmental and cost-effective strategies for the use of coal combustion by-products (CCBPs), mainly unburned carbon in fly ash. Unburned carbon is nowadays regarded as a waste product and its fate is mainly disposal, due to the present lack of efficient routes for its utilization. However, unburned carbon is a potential precursor for the production of adsorbent carbons, since it has gone through a devolatilization process while in the combustor, and therefore, only requires to be activated. Accordingly, the principal objective of this work was to characterize and utilize the unburned carbon in fly ash for the production of activated carbons. The unburned carbon samples were collected from different combustion systems, including pulverized utility boilers, a utility cyclone, a stoker, and a fluidized bed combustor. LOI (loss-on-ignition), proximate, ultimate, and petrographic analyses were conducted, and the surface areas of the samples were characterized by N2 adsorption isotherms at 77K. The LOIs of the unburned carbon samples varied between 21.79-84.52%. The proximate analyses showed that all the samples had very low moisture contents (0.17 to 3.39 wt %), while the volatile matter contents varied between 0.45 to 24.82 wt%. The elemental analyses show that all the unburned carbon samples consist mainly of carbon with very little hydrogen, nitrogen, sulfur and oxygen In addition, the potential use of unburned carbon as precursor for activated carbon (AC) was investigated. Activated carbons with specific surface area up to 1075m{sup 2}/g were produced from the unburned carbon. The porosity of the resultant activated carbons was related to the properties of the unburned carbon feedstock and the activation conditions used. It was found that not all the unburned carbon samples are equally suited for activation, and furthermore, their potential as activated carbons precursors could be

  3. Plasma vasopressin and renin activity in women exposed to bed rest and +G/z/ acceleration

    NASA Technical Reports Server (NTRS)

    Keil, L. C.; Ellis, S.

    1976-01-01

    To study the effect of prolonged recumbency on plasma vasopressin and renin activity, eight women were subjected to 17 days of absolute bed rest. The tolerance to +3G vertical acceleration of the subjects was tested before and after 14 days of bed rest. From day 2 and through day 17 of bed rest, plasma arginine vasopressin (AVP) levels were reduced 33%. Plasma renin activity (PRA) increased 91% above ambulatory control values from days 10 through 15 of bed rest. When compared to precentrifuge values, exposure to vertical acceleration prior to bed rest provoked a 20-fold rise in mean plasma AVP but resulted in only a slight increase in PRA. After bed rest, acceleration increased plasma AVP 7-fold; however, the magnitude of this increase was less than the post +3G acceleration value obtained prior to bed rest. After bed rest, no significant rise was noted in PRA following +3G acceleration. This study demonstrates that prolonged bed rest leads to a significant rise in the PRA of female subjects, while exposure to positive vertical acceleration provokes a marked rise in plasma AVP.

  4. Metalloradical-catalyzed aliphatic carbon-carbon activation of cyclooctane.

    PubMed

    Chan, Yun Wai; Chan, Kin Shing

    2010-05-26

    The aliphatic carbon-carbon activation of c-octane was achieved via the addition of Rh(ttp)H to give Rh(ttp)(n-octyl) in good yield under mild reaction conditions. The aliphatic carbon-carbon activation was Rh(II)(ttp)-catalyzed and was very sensitive to porphyrin sterics.

  5. Evidence for Methyl-Compound-Activated Life in Coal Bed System 2 km Below Sea Floor

    NASA Astrophysics Data System (ADS)

    Trembath-reichert, E.; Morono, Y.; Dawson, K.; Wanger, G.; Bowles, M.; Heuer, V.; Hinrichs, K. U.; Inagaki, F.; Orphan, V. J.

    2014-12-01

    IODP Expedition 337 set the record for deepest marine scientific drilling down to 2.4 kmbsf. This cruise also had the unique opportunity to retrieve deep cores from the Shimokita coal bed system in Japan with the aseptic and anaerobic conditions necessary to look for deep life. Onboard scientists prepared nearly 1,700 microbiology samples shared among five different countries to study life in the deep biosphere. Samples spanned over 1 km in sampling depths and include representatives of shale, sandstone, and coal lithologies. Findings from previous IODP and deep mine expeditions suggest the genetic potential for methylotrophy in the deep subsurface, but it has yet to be observed in incubations. A subset of Expedition 337 anoxic incubations were prepared with a range of 13C-methyl substrates (methane, methylamine, and methanol) and maintained near in situ temperatures. To observe 13C methyl compound metabolism over time, we monitored the δ13C of the dissolved inorganic carbon (by-product of methyl compound metabolism) over a period of 1.5 years. Elemental analysis (EA), ion chromatograph (IC), 13C volatile fatty acid (VFA), and mineral-associated microscopy data were also collected to constrain initial and endpoint conditions in these incubations. Our geochemical evidence suggests that the coal horizon incubated with 13C-methane showed the highest activity of all methyl incubations. This provides the first known observation of methane-activated metabolism in the deep biosphere, and suggests there are not only active cells in the deeply buried terrigenous coal bed at Shimokita, but the presence of a microbial community activated by methylotrophic compounds.

  6. Effectiveness of powered hospital bed movers for reducing physiological strain and back muscle activation.

    PubMed

    Daniell, Nathan; Merrett, Simon; Paul, Gunther

    2014-07-01

    Battery powered bed movers are becoming increasingly common within the hospital setting. The use of powered bed movers is believed to result in reduced physical efforts required by health care workers, which may be associated with a decreased risk of occupation related injuries. However, little work has been conducted assessing how powered bed movers impact on levels of physiological strain and muscle activation for the user. The muscular efforts associated with moving hospital beds using three different methods; powered StaminaLift Bed Mover (PBM1), powered Gzunda Bed Mover (PBM2) and manual pushing were measured on six male subjects. Fourteen muscles were assessed moving a weighted hospital bed along a standardized route in an Australian hospital environment. Trunk inclination and upper spine acceleration were also quantified. Powered bed movers exhibited significantly lower muscle activation levels than manual pushing for the majority of muscles. When using the PBM1, users adopted a more upright posture which was maintained while performing different tasks (e.g. turning a corner, entering a lift), while trunk inclination varied considerably for manual pushing and the PBM2. The reduction in lower back muscular activation levels may result in lower incidence of lower back injury.

  7. JV Task 90 - Activated Carbon Production from North Dakota Lignite

    SciTech Connect

    Steven Benson; Charlene Crocker; Rokan Zaman; Mark Musich; Edwin Olson

    2008-03-31

    The Energy & Environmental Research Center (EERC) has pursued a research program for producing activated carbon from North Dakota lignite that can be competitive with commercial-grade activated carbon. As part of this effort, small-scale production of activated carbon was produced from Fort Union lignite. A conceptual design of a commercial activated carbon production plant was drawn, and a market assessment was performed to determine likely revenue streams for the produced carbon. Activated carbon was produced from lignite coal in both laboratory-scale fixed-bed reactors and in a small pilot-scale rotary kiln. The EERC was successfully able to upgrade the laboratory-scale activated carbon production system to a pilot-scale rotary kiln system. The activated carbon produced from North Dakota lignite was superior to commercial grade DARCO{reg_sign} FGD and Rheinbraun's HOK activated coke product with respect to iodine number. The iodine number of North Dakota lignite-derived activated carbon was between 600 and 800 mg I{sub 2}/g, whereas the iodine number of DARCO FGD was between 500 and 600 mg I{sub 2}/g, and the iodine number of Rheinbraun's HOK activated coke product was around 275 mg I{sub 2}/g. The EERC performed both bench-scale and pilot-scale mercury capture tests using the activated carbon made under various optimization process conditions. For comparison, the mercury capture capability of commercial DARCO FGD was also tested. The lab-scale apparatus is a thin fixed-bed mercury-screening system, which has been used by the EERC for many mercury capture screen tests. The pilot-scale systems included two combustion units, both equipped with an electrostatic precipitator (ESP). Activated carbons were also tested in a slipstream baghouse at a Texas power plant. The results indicated that the activated carbon produced from North Dakota lignite coal is capable of removing mercury from flue gas. The tests showed that activated carbon with the greatest iodine number

  8. Plasma lactic dehydrogenase activities in men during bed rest with exercise training

    NASA Technical Reports Server (NTRS)

    Greenleaf, J. E.; Juhos, L. T.; Young, H. L.

    1985-01-01

    Peak oxygen uptake and the activity of lactic dehydrogenase (LDH-T) and its five isoenzymes were measured by spectrophotometer in seven men before, during, and after bed rest and exercise training. Exercise training consisted of isometric leg exercises of 250 kcal/hr for a period of one hour per day. It is found that LDH-T was reduced by 0.05 percent in all three regimens by day 10 of bed rest, and that the decrease occurred at different rates. The earliest reduction in LDH-T activity in the no-exercise regimen was associated with a decrease in peak oxygen uptake of 12.3 percent. It is concluded that isometric (aerobic) muscular strength training appear to maintain skeletal muscle integrity better during bed rest than isotonic exercise training. Reduced hydrostatic pressure during bed rest, however, ultimately counteracts the effects of both moderate isometric and isotonic exercise training, and may result in decreased LDH-T activity.

  9. 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.

  10. Removing lead in drinking water with activated carbon

    SciTech Connect

    Taylor, R.M.; Kuennen, R.W. )

    1994-02-01

    A point-of-use (POU) granular activated carbon (GAC) fixed bed adsorber (FBA) was evaluated for reduction of soluble and insoluble lead from drinking water. Some of the factors which affect lead removal by GAC were evaluated, such as carbon type, solution pH, and a limited amount of work on competitive interactions. The design criteria for lead reduction by a POU device are also addressed. Minicolumns were used to evaluate the capacity of carbon for lead under a variety of conditions. The importance of surface chemistry of the carbon and the relationship with the pH of the water for lead reduction was demonstrated. Results indicate that a properly designed POU-GAC-FBA can reduce lead in drinking water to below the EPA action level of 15 ppb while being tested under a variety of conditions as specified under the National Sanitation Foundation (NSF) International Standard 53 test protocol. 37 refs., 9 figs., 1 tab.

  11. Systematic reviews of bed rest and advice to stay active for acute low back pain.

    PubMed Central

    Waddell, G; Feder, G; Lewis, M

    1997-01-01

    BACKGROUND: In the United Kingdom (UK), 9% of adults consult their doctor annually with back pain. The treatment recommendations are based on orthopaedic teaching, but the current management is causing increasing dissatisfaction. Many general practitioners (GPs) are confused about what constitutes effective advice. AIM: To review all randomized controlled trials of bed rest and of medical advice to stay active for acute back pain. METHOD: A systematic review based on a search of MEDLINE and EMBASE from 1966 to April 1996 with complete citation tracking for randomized controlled trials of bed rest or medical advice to stay active and continue ordinary daily activities. The inclusion criteria were: primary care setting, patients with low back pain of up to 3 months duration, and patient-centred outcomes (rate of recovery from the acute attack, relief of pain, restoration of function, satisfaction with treatment, days off work and return to work, development of chronic pain and disability, recurrent attacks, and further health care use). RESULTS: Ten trials of bed rest and eight trials of advice to stay active were identified. Consistent findings showed that bed rest is not an effective treatment for acute low back pain but may delay recovery. Advice to stay active and to continue ordinary activities results in a faster return to work, less chronic disability, and fewer recurrent problems. CONCLUSION: A simple but fundamental change from the traditional prescription of bed rest to positive advice about staying active could improve clinical outcomes and reduce the personal and social impact of back pain. PMID:9474831

  12. 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.

  13. Activated, coal-based carbon foam

    SciTech Connect

    Rogers, Darren Kenneth; Plucinski, Janusz Wladyslaw

    2009-06-09

    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.

  14. Carbon tetrachloride replacement compounds for organic vapor air-purifying respirator cartridge and activated carbon testing--a review.

    PubMed

    Moyer, E S; Smith, S J; Wood, G O

    2001-01-01

    This article reviews efforts by researchers and organizations around the world to identify chemicals as substitutes for carbon tetrachloride in measuring activated carbon activity (adsorption capacity) or organic vapor air-purifying respirator cartridge (or other packed carbon bed) breakthrough times. Such measurements usually are done to determine if a minimum performance standard is met. Different criteria have been established, supporting data developed and used, and conclusions reached. This article presents relevant published, unpublished, obscure, and recalculated data which the reader can use to make a choice of replacement chemical and testing conditions. No recommendations for a specific replacement chemical are endorsed or promoted in this review. PMID:11549144

  15. 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

  16. Properties of Spent Active Coke Particles Analysed via Comminution in Spouted Bed

    PubMed Central

    Buczek, Bronislaw

    2013-01-01

    Samples of active coke, fresh and spent after cleaning flue gases from communal waste incinerators, were investigated. The outer layers of both coke particles were separately removed by comminution in a spouted bed. The samples of both active cokes were analysed by means of densities, mercury porosimetry, and adsorption technique. Remaining cores were examined to determine the degree of consumption of coke by the sorption of hazardous emissions (SO2, HCl, and heavy metals) through its bed. Differences in contamination levels within the porous structure of the particles were estimated. The study demonstrated the effectiveness of commercial active coke in the cleaning of flue gases. PMID:24459454

  17. Development of moving bed simulation model for carbon capture from fossil energy systems.

    SciTech Connect

    Kim, H.; Miller, D.

    2011-01-01

    The capture and separation of carbon dioxide (CO2) has been identified as a high-priority topic to cope with global climate change. Fossil fuels currently supply the most of the world's energy needs, and their utilization is the major source of the anthropogenic CO2 emission [1]. Particularly, the existing coal-fired power plants annually emit about 2 billion tons of CO2 which is equivalent to two-thirds of the total emissions from U.S. power sector [2]. Therefore, it is critical to develop the cost-effective technologies to mitigate this problem. There are three options for capture for capturing CO2 from fossil energy system: post-combustion capture, pre-combustion capture, and oxy-combustion. Among them, post-combustion capture has the greatest near-term potential for reducing CO2 emission, because it can be applied to the existing coal-fired power plant with relative ease through a retrofit. The current commercially available solvent-based processes have advantages of fast kinetics and strong reactions, however only at a significant cost and efficiency penalty. Recently, various solid sorbents are being explored for one of promising CO2 capture technology, which are expected to reduce energy requirement and water usage with the approaches of fluidized or moving bed. However, solids are inherently more difficult to work with than liquids and no large scale system has yet been commercialized. In this study, we developed the rigorous 1-D PDE model for moving beds in Aspen Custom Modeler; the entire system consists of adsorbers, regenerators, and auxiliary equipment. The simulation result will be expected to compare with those of other post-combustion processes. We will deal with not only advantages of lower capital costs and power requirements but also problems associated with pressure drop and heat transfer.

  18. Treatment bed microbiological control

    NASA Technical Reports Server (NTRS)

    Janauer, Gilbert E.; Fitzpatrick, Timothy W.; Kril, Michael B.; Wilber, Georgia A.; Sauer, Richard L.

    1987-01-01

    The effects of microbial fouling on treatment bed (TB) performance are being studied. Fouling of activated carbon (AC) and ion exchange resins (IEX) by live and devitalized bacteria can cause decreased capacity for selected sorbates with AC and IEX TB. More data are needed on organic species removal in the trace region of solute sorption isotherms. TB colonization was prevented by nonclassical chemical disinfectant compositions (quaternary ammonium resins) applied in suitable configurations. Recently, the protection of carbon beds via direct disinfectant impregnation has shown promise. Effects (of impregnation) upon bed sorption/removal characteristics are to be studied with representative contaminants. The potential need to remove solutes added or produced during water disinfection and/or TB microbiological control must be investigated.

  19. FLUIDIZED BED STEAM REFORMING FOR TREATMENT AND IMMOBILIZATION OF LOW-ACTIVITY WASTE

    SciTech Connect

    HEWITT WM

    2011-04-08

    This report is one of four reports written to provide background information regarding immobilization technologies remaining under consideration for supplemental immobilization of Hanford's low-activity waste. This paper provides the reader a general understanding of fluidized bed steam reforming and its possible application to treat and immobilize Hanford low-activity waste.

  20. Identification and active disturbance rejection for the JPL Phase B Test Bed

    NASA Astrophysics Data System (ADS)

    Eldred, Daniel B.; Gibson, J. S.; Li, Wu-Jeng

    1993-09-01

    Active disturbance rejection to minimize optical path length error is illustrated by experimental results from the JPL Phase B Test Bed, which incorporates an interferometric sensor and a controllable trolley mounted on a flexible truss structure. The controller actively isolates the optical instruments from structural vibrations induced by external disturbances consisting of linear combinations of sinusoidal signals.

  1. Bed rest suppresses bioassayable growth hormone release in response to muscle activity

    NASA Technical Reports Server (NTRS)

    McCall, G. E.; Goulet, C.; Grindeland, R. E.; Hodgson, J. A.; Bigbee, A. J.; Edgerton, V. R.

    1997-01-01

    Hormonal responses to muscle activity were studied in eight men before (-13 or -12 and -8 or -7 days), during (2 or 3, 8 or 9, and 13 or 14 days) and after (+2 or +3 and +10 or +11 days) 17 days of bed rest. Muscle activity consisted of a series of unilateral isometric plantar flexions, including 4 maximal voluntary contractions (MVCs), 48 contractions at 30% MVC, and 12 contractions at 80% MVC, all performed at a 4:1-s work-to-rest ratio. Blood was collected before and immediately after muscle activity to measure plasma growth hormone by radioimmunoassay (IGH) and by bioassay (BGH) of tibia epiphyseal cartilage growth in hypophysectomized rats. Plasma IGH was unchanged by muscle activity before, during, or after bed rest. Before bed rest, muscle activity increased (P < 0.05) BGH by 66% at -13 or -12 days (2,146 +/- 192 to 3,565 +/- 197 microg/l) and by 92% at -8 or -7 days (2,162 +/- 159 to 4,161 +/- 204 microg/l). After 2 or 3 days of bed rest, there was no response of BGH to the muscle activity, a pattern that persisted through 8 or 9 days of bed rest. However, after 13 or 14 days of bed rest, plasma concentration of BGH was significantly lower after than before muscle activity (2,594 +/- 211 to 2,085 +/- 109 microg/l). After completion of bed rest, muscle activity increased BGH by 31% at 2 or 3 days (1,807 +/- 117 to 2,379 +/- 473 microg/l; P < 0.05), and by 10 or 11 days the BGH response was similar to that before bed rest (1,881 +/- 75 to 4,160 +/- 315 microg/l; P < 0.05). These data demonstrate that the ambulatory state of an individual can have a major impact on the release of BGH, but not IGH, in response to a single bout of muscle activity.

  2. Stocks and sources of carbon buried in the salt marshes and seagrass beds of Patos Lagoon Estuary, Southern Brazil

    NASA Astrophysics Data System (ADS)

    Patterson, Elizabeth; Johnson, Beverly; Dostie, Philip; Copertino, Margareth

    2016-04-01

    This project investigates carbon stocks in salt marshes and seagrass beds in the Patos Lagoon estuary, the largest choked lagoon in the world, located in Southern Brazil. The study was conducted in the mesohaline region, at three shallow shoals. At each shoal, three sediment cores (50 cm deep) and plant biomass samples (above and belowground) were collected along a transect line, spanning from the marsh to seagrass beds (total = 9 sediment cores). The 50cm cores were subsampled and analyzed for organic carbon (C) and nitrogen (N) content, C/N ratios, and the isotope ratios of 13C/12C, and 15N/14N. The organic carbon content of these sediments ranged between 10% (in surface sediments) and 1% (deeper in the core), suggesting that both the salt marshes and seagrass beds in this region are sequestering carbon. Early results indicate that cores taken in marsh dominated by C3 plants (Scirpus maritimus) tended to be the most depleted in 13C with δ13C values around -25‰. Cores taken in marsh dominated by C4 plants (Spartina alterniflora, Spartina densiflora), seagrass beds (Ruppia maritima) , and non vegetated areas were generally isotopically heavier with δ13C values ranging -20‰ to -15‰, indicating a mix of organic sources in the sediments. The δ15N values and C/N ratios both varied with most values falling in a range of 2-8‰ and 7-20 respectively. Analysis of the δ 34S isotope composition of the sediments is currently underway and may provide better information on the relative contributions of macro and micro algae in the sediments. The present data will reveal the carbon stock size, as well as the types and history of organic matter deposition in Patos Lagoon estuary.

  3. Expression of syndepositional tectonic uplift in Permian Goose Egg formation (Phosphoria equivalent) carbonates and red beds of Sheep Mountain anticline, Bighorn basin, Wyoming

    SciTech Connect

    Simmons, S.P.; Ulmer, D.S.; Scholle, P.A.

    1989-03-01

    Based on detailed field observations at Sheep Mountain, a doubly plunging anticline in the northeastern Bighorn basin in Wyoming, there appears to have been active tectonic uplift at this site contemporaneous with Pennsylvanian and Permian sedimentation. The Permian (Leonardian to Guadalupian) Goose Egg Formation at Sheep Mountain consists of 25-60 m of silty red beds (including minor carbonate and evaporite units) capped by 15-30 m of dominantly intertidal carbonates (the Ervay Member). A strong lateral variation of facies normal to the trend of the anticline is found within the red-bed sequence: carbonate beds on the anticline flanks are transitional with a gypsum/anhydrite facies along the crest. Similarly, shales on the anticline limbs grade into sandstones near the fold axis, indicating a paleohigh roughly coincidental with the present-day anticline crest. Ervay deposition (late Guadalupian) was marked by a more extensive uplifted structure in a marginal marine setting. On Sheep Mountain the unit is typified by intertidal fenestral carbonates, whereas outcrops to the east suggest a restricted marine facies and outcrops to the west reflect a more open marine environment. Thin sand lenses present in the Ervay are thought to represent terrigenous sediments blown onto the sometimes emergent bank which were then captured through adhesion and cementation. Anticlinal features similar to Sheep Mountain are common along the eastern margin of the Bighorn basin. When found in the subsurface, these structures are often associated with hydrocarbon production from the Ervay Member. Tectonic uplift contemporaneous with deposition of this unit may explain the localization of the productive fenestral facies on the present-day anticlines.

  4. Kinetics of electrooxidation of landfill leachate in a three-dimensional carbon bed electrochemical reactor.

    PubMed

    Nageswara Rao, Neti; Rohit, Misra; Nitin, Gedam; Parameswaran, P N; Astik, J K

    2009-08-01

    The electrooxidation of high strength leachate from an industrial solid waste landfill site was carried out in a three-dimensional carbon bed electrode reactor (TDR). This paper discusses the kinetics and mechanism of electrooxidation on the basis of time course variation of COD, TOC and TKN (total Kjeldahl nitrogen) from the raw leachate. The batch experiments were run at different applied currents (1-3 A) for a period of 6h. A two-stage pseudo-first order reaction kinetics model was developed based on the initial rapid removal of pollutants (Phase I) followed by slow oxidation kinetics (Phase II). About 60-64% COD was removed within 1h with a rate constant 5.83 x 10(-3) min(-1) in Phase I, which was near 5-7 times greater than that of Phase II (0.81-1.03 x 10(-3)min(-1)). The mineralization efficiency was found to be significant in the range 0.83-0.84. The apparent faradic efficiency and specific energy consumption for COD removal were also estimated. The mechanism of electrooxidation was discussed with the help of adsorption, kinetic and SEM results.

  5. Role of nitrogen in pore development in activated carbon prepared by potassium carbonate activation of lignin

    NASA Astrophysics Data System (ADS)

    Tsubouchi, Naoto; Nishio, Megumi; Mochizuki, Yuuki

    2016-05-01

    The present work focuses on the role of nitrogen in the development of pores in activated carbon produced from lignin by K2CO3 activation, employing a fixed bed reactor under a high-purity He stream at temperatures of 500-900 °C. The specific surface area and pore volume obtained by activation of lignin alone are 230 m2/g and 0.13 cm3/g at 800 °C, and 540 m2/g and 0.31 cm3/g at 900 °C, respectively. Activation of a mixture of lignin and urea provides a significant increase in the surface area and volume, respectively reaching 3300-3400 m2/g and 2.0-2.3 cm3/g after holding at 800-900 °C for 1 h. Heating a lignin/urea/K2CO3 mixture leads to a significant decrease in the yield of released N-containing gases compared to the results for urea alone and a lignin/urea mixture, and most of the nitrogen in the urea is retained in the solid phase. X-ray photoelectron spectroscopy and X-ray diffraction analyses clearly show that part of the remaining nitrogen is present in heterocyclic structures (for example, pyridinic and pyrrolic nitrogen), and the rest is contained as KOCN at ≤600 °C and as KCN at ≥700 °C, such that the latter two compounds can be almost completely removed by water washing. The fate of nitrogen during heating of lignin/urea/K2CO3 and role of nitrogen in pore development in activated carbon are discussed on the basis of the results mentioned above.

  6. Carbon and nutrient removal in a dual-media fluidized bed reactor.

    PubMed

    Safferman, Steven I; Mashingaidze, Ella M; McMackin, Stephanie A

    2003-09-01

    A dual-media fluidized bed is a unique reactor design containing two distinct media that results in two segregated treatment zones. By the strategic use of these two zones, this design has the potential to remove both BOD and nutrients (nitrogen and phosphorus) in a single compact reactor. Three operational strategies are conceivable. The first is to maintain a microbiological zone close to the influent to achieve BOD and nitrogen removal. The zone above would contain an exchange media to remove phosphorous. In another scenario, the lower zone would be kept aerobic and the higher zone anoxic. This would enhance denitrification. In the third scenario, the first two are combined by having the exchange media serve as the anoxic zone or including an independent third zone (aerobic, anoxic, and exchange). This scenario could result in the comprehensive treatment of BOD, nitrogen, and phosphorus removal. This proof-of-concept research primarily investigated the first scenario and provided preliminary data for the other two. A low-loaded operating strategy was used to minimize the inherent disadvantages of a fluidized bed reactor, primarily caused by excessive biofilm growth. The reactor was operated for approximately 1 year using sand and activated alumina as the two media. Good separation with minimum mixing at the interface resulted. BOD and phosphorus removal and nitrification were consistently very good during non-transitional periods. Denitrification varied depending on the influent concentration, dissolved oxygen, and oxidation/reduction potential. Preliminary data also indicated that when a low recirculation ratio is used, denitrification could be enhanced. There appears to be a potential difficulty, however, in exchanging phosphorous using activated alumina under low oxidation/reduction potential conditions.

  7. Adsorption of herbicides using activated carbons

    SciTech Connect

    Derbyshire, F.; Jagtoyan, M.; Lafferty, C.; Kimber, G.

    1996-10-01

    This work describes development of a series of novel activated carbon materials and their testing for possible water treatment applications by studying the adsorption of sodium pentachlorphenolate, PCP (a common herbicide/wood preservative). Although the application of activated carbons is an established technology for the treatment of public water supplies, there is a growing need for materials with higher selectivity and adsorptive capacities as well as high abrasion resistance. The materials that will be discussed include extruded wood-derived carbons with novel pore size distributions and high hardness, as well as activated carbon fiber composites. Comparisons will be made with commercial granular water treatment carbons.

  8. Breakthrough CO₂ adsorption in bio-based activated carbons.

    PubMed

    Shahkarami, Sepideh; Azargohar, Ramin; Dalai, Ajay K; Soltan, Jafar

    2015-08-01

    In this work, the effects of different methods of activation on CO2 adsorption performance of activated carbon were studied. Activated carbons were prepared from biochar, obtained from fast pyrolysis of white wood, using three different activation methods of steam activation, CO2 activation and Potassium hydroxide (KOH) activation. CO2 adsorption behavior of the produced activated carbons was studied in a fixed-bed reactor set-up at atmospheric pressure, temperature range of 25-65°C and inlet CO2 concentration range of 10-30 mol% in He to determine the effects of the surface area, porosity and surface chemistry on adsorption capacity of the samples. Characterization of the micropore and mesopore texture was carried out using N2 and CO2 adsorption at 77 and 273 K, respectively. Central composite design was used to evaluate the combined effects of temperature and concentration of CO2 on the adsorption behavior of the adsorbents. The KOH activated carbon with a total micropore volume of 0.62 cm(3)/g and surface area of 1400 m(2)/g had the highest CO2 adsorption capacity of 1.8 mol/kg due to its microporous structure and high surface area under the optimized experimental conditions of 30 mol% CO2 and 25°C. The performance of the adsorbents in multi-cyclic adsorption process was also assessed and the adsorption capacity of KOH and CO2 activated carbons remained remarkably stable after 50 cycles with low temperature (160°C) regeneration.

  9. Efficient control of odors and VOC emissions via activated carbon technology.

    PubMed

    Mohamed, Farhana; Kim, James; Huang, Ruey; Nu, Huong Ton; Lorenzo, Vlad

    2014-07-01

    This research study was undertaken to enhance the efficiency and economy of carbon scrubbers in controlling odors and volatile organic compounds (VOCs) at the wastewater collection and treatment facilities of the Bureau of Sanitation, City of Los Angeles. The butane activity and hydrogen sulfide breakthrough capacity of activated carbon were assessed. Air streams were measured for odorous gases and VOCs and removal efficiency (RE) determined. Carbon towers showed average to excellent removal of odorous compounds, VOCs, and siloxanes; whereas, wet scrubbers demonstrated good removal of odorous compounds but low to negative removal of VOCs. It was observed that the relative humidity and empty bed contact time are one of the most important operating parameters of carbon towers impacting the pollutant RE. Regular monitoring of activated carbon and VOCs has resulted in useful information on carbon change-out frequency, packing recommendations, and means to improve performance of carbon towers.

  10. 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...

  11. Remarkable enhancement of O₂ activation on yttrium-stabilized zirconia surface in a dual catalyst bed.

    PubMed

    Richard, Mélissandre; Can, Fabien; Duprez, Daniel; Gil, Sonia; Giroir-Fendler, Anne; Bion, Nicolas

    2014-10-13

    Yttrium-stabilized zirconia (YSZ) has been extensively studied as an electrolyte material for solid oxide fuel cells (SOFC) but its performance in heterogeneous catalysis is also the object of a growing number of publications. In both applications, oxygen activation on the YSZ surface remains the step that hinders utilization at moderate temperature. It was demonstrated by oxygen isotope exchange that a dual catalyst bed system consisting of two successive LaMnO3 and YSZ beds without intimate contact drastically enhances oxygen activation on the YSZ surface at 698 K. It can be concluded that LaMnO3 activates the triplet ground-state of molecular oxygen into a low-lying singlet state, thereby facilitating the activation of the O2 molecule on the YSZ oxygen vacancy sites. This phenomenon is shown to improve the catalytic activity of the LaMnO3-Pd/YSZ system for the partial oxidation of methane.

  12. An active wound dressing for controlled convective mass transfer with the wound bed.

    PubMed

    Cabodi, Mario; Cross, Valerie L; Qu, Zheng; Havenstrite, Karen L; Schwartz, Suzanne; Stroock, Abraham D

    2007-07-01

    Conventional wound dressings-gauze, plastic films, foams, and gels-do not allow for spatial and temporal control of the soluble chemistry within the wound bed, and are thus limited to a passive role in wound healing. Here, we present an active wound dressing (AWD) designed to control convective mass transfer with the wound bed; this mass transfer provides a means to tailor and monitor the chemical state of a wound and, potentially, to aid the healing process. We form this AWD as a bilayer of porous poly(hydroxyethyl methacrylate) (pHEMA) and silicone; the pHEMA acts as the interface with the wound bed, and a layer of silicone provides a vapor barrier and a support for connecting to external reservoirs and pumps. We measure the convective permeability of the pHEMA sponge, and use this value to design a device with a spatially uniform flow profile. We quantify the global coefficient of mass transfer of the AWD on a dissolvable synthetic surface, and compare it to existing theories of mass transfer in porous media. We also operate the AWD on model wound beds made of calcium alginate gel to demonstrate extraction and delivery of low molecular weight solutes and a model protein. Using this system, we demonstrate both uniform mass transfer over the entire wound bed and patterned mass transfer in three spatially distinct regions. Finally, we discuss opportunities and challenges for the clinical application of this design of an AWD.

  13. An active wound dressing for controlled convective mass transfer with the wound bed.

    PubMed

    Cabodi, Mario; Cross, Valerie L; Qu, Zheng; Havenstrite, Karen L; Schwartz, Suzanne; Stroock, Abraham D

    2007-07-01

    Conventional wound dressings-gauze, plastic films, foams, and gels-do not allow for spatial and temporal control of the soluble chemistry within the wound bed, and are thus limited to a passive role in wound healing. Here, we present an active wound dressing (AWD) designed to control convective mass transfer with the wound bed; this mass transfer provides a means to tailor and monitor the chemical state of a wound and, potentially, to aid the healing process. We form this AWD as a bilayer of porous poly(hydroxyethyl methacrylate) (pHEMA) and silicone; the pHEMA acts as the interface with the wound bed, and a layer of silicone provides a vapor barrier and a support for connecting to external reservoirs and pumps. We measure the convective permeability of the pHEMA sponge, and use this value to design a device with a spatially uniform flow profile. We quantify the global coefficient of mass transfer of the AWD on a dissolvable synthetic surface, and compare it to existing theories of mass transfer in porous media. We also operate the AWD on model wound beds made of calcium alginate gel to demonstrate extraction and delivery of low molecular weight solutes and a model protein. Using this system, we demonstrate both uniform mass transfer over the entire wound bed and patterned mass transfer in three spatially distinct regions. Finally, we discuss opportunities and challenges for the clinical application of this design of an AWD. PMID:17106898

  14. In-Situ Regeneration of Saturated Granular Activated Carbon by an Iron Oxide Nanocatalyst

    EPA Science Inventory

    Granular activated carbon (GAC) can remove trace organic pollutants and natural organic matter (NOM) from industrial and municipal waters. This paper evaluates an iron nanocatalyst approach, based on Fenton-like oxidation reactions, to regenerate spent GAC within a packed bed con...

  15. An overview of the issues: physiological effects of bed rest and restricted physical activity

    NASA Technical Reports Server (NTRS)

    Convertino, V. A.; Bloomfield, S. A.; Greenleaf, J. E.

    1997-01-01

    Reduction of exercise capacity with confinement to bed rest is well recognized. Underlying physiological mechanisms include dramatic reductions in maximal stroke volume, cardiac output, and oxygen uptake. However, bed rest by itself does not appear to contribute to cardiac dysfunction. Increased muscle fatigue is associated with reduced muscle blood flow, red cell volume, capillarization and oxidative enzymes. Loss of muscle mass and bone density may be reflected by reduced muscle strength and higher risk for injury to bones and joints. The resultant deconditioning caused by bed rest can be independent of the primary disease and physically debilitating in patients who attempt to reambulate to normal active living and working. A challenge to clinicians and health care specialists has been the identification of appropriate and effective methods to restore physical capacity of patients during or after restricted physical activity associated with prolonged bed rest. The examination of physiological responses to bed rest deconditioning and exercise training in healthy subjects has provided significant information to develop effective rehabilitation treatments. The successful application of acute exercise to enhance orthostatic stability, daily endurance exercise to maintain aerobic capacity, or specific resistance exercises to maintain musculoskeletal integrity rather than the use of surgical, pharmacological, and other medical treatments for clinical conditions has been enhanced by investigation and understanding of underlying mechanisms that distinguish physical deconditioning from the disease. This symposium presents an overview of cardiovascular and musculoskeletal deconditioning associated with reduced physical work capacity following prolonged bed rest and exercise training regimens that have proven successful in ameliorating or reversing these adverse effects.

  16. Nitrogen and carbon removal efficiency of a polyvinyl alcohol gel based moving bed biofilm reactor system.

    PubMed

    Gani, Khalid Muzamil; Singh, Jasdeep; Singh, Nitin Kumar; Ali, Muntjeer; Rose, Vipin; Kazmi, A A

    2016-01-01

    In this study, the effectiveness of polyvinyl alcohol (PVA) gel beads in treating domestic wastewater was investigated: a moving bed biofilm reactor (MBBR) configuration (oxic-anoxic and oxic) with 10% filling fraction of biomass carriers was operated in a continuously fed regime at temperatures of 25, 20, 15 and 6 °C with hydraulic retention times (HRTs) of 32 h, 18 h, 12 h and 9 h, respectively. Influent loadings were in the range of 0.22-1.22 kg N m(-3) d(-1) (total nitrogen (TN)), 1.48-7.82 kg chemical oxygen demand (COD) m(-3) d(-1) (organic) and 0.12-0.89 kg NH4(+)-N m(-3)d(-1) (ammonia nitrogen). MBBR performance resulted in the maximum TN removal rate of 1.22 kg N m(-3) d(-1) when the temperature and HRT were 6 °C and 9 h, respectively. The carbon removal rate at this temperature and HRT was 6.82 kg COD m(-3) d(-1). Ammonium removal rates ranged from 0.13 to 0.75 kg NH4(+)-N m(-3) d(-1) during the study. Total phosphorus and suspended solid removal efficiency ranged from 84 to 98% and 85 to 94% at an influent concentration of 3.3-7.1 mg/L and 74-356 mg/L, respectively. The sludge wasted from the MBBR exhibited light weight features characterized by sludge volume index value of 185 mL/g. Experimental data obtained can be useful in further developing the concept of PVA gel based wastewater treatment systems.

  17. Nitrogen and carbon removal efficiency of a polyvinyl alcohol gel based moving bed biofilm reactor system.

    PubMed

    Gani, Khalid Muzamil; Singh, Jasdeep; Singh, Nitin Kumar; Ali, Muntjeer; Rose, Vipin; Kazmi, A A

    2016-01-01

    In this study, the effectiveness of polyvinyl alcohol (PVA) gel beads in treating domestic wastewater was investigated: a moving bed biofilm reactor (MBBR) configuration (oxic-anoxic and oxic) with 10% filling fraction of biomass carriers was operated in a continuously fed regime at temperatures of 25, 20, 15 and 6 °C with hydraulic retention times (HRTs) of 32 h, 18 h, 12 h and 9 h, respectively. Influent loadings were in the range of 0.22-1.22 kg N m(-3) d(-1) (total nitrogen (TN)), 1.48-7.82 kg chemical oxygen demand (COD) m(-3) d(-1) (organic) and 0.12-0.89 kg NH4(+)-N m(-3)d(-1) (ammonia nitrogen). MBBR performance resulted in the maximum TN removal rate of 1.22 kg N m(-3) d(-1) when the temperature and HRT were 6 °C and 9 h, respectively. The carbon removal rate at this temperature and HRT was 6.82 kg COD m(-3) d(-1). Ammonium removal rates ranged from 0.13 to 0.75 kg NH4(+)-N m(-3) d(-1) during the study. Total phosphorus and suspended solid removal efficiency ranged from 84 to 98% and 85 to 94% at an influent concentration of 3.3-7.1 mg/L and 74-356 mg/L, respectively. The sludge wasted from the MBBR exhibited light weight features characterized by sludge volume index value of 185 mL/g. Experimental data obtained can be useful in further developing the concept of PVA gel based wastewater treatment systems. PMID:27054722

  18. Synchronous droplets as a test bed for pulsatory active fluids

    NASA Astrophysics Data System (ADS)

    Katsikis, Georgios; Prakash, Manu

    2014-11-01

    Collective behavior in many-body systems has been studied extensively focusing on a wide range of interacting entities including: flocking animals, sedimenting particles and microfluidic droplets among others. Here, we propose an experimental platform to explore an oscillatory active fluid with synchronous ferrofluid droplets immersed in an immiscible carrier fluid in a Hele-Shaw configuration. The droplets are organized and actuated on a 2-D uniform grid through application of a precessive magnetic field. The state of our system is dependent on three parameters: the grid occupancy with fluid droplets, the grid geometry and the magnetic field. We study the long range orientational order of our system over a range of those parameters by tracking the motion of the droplets and analyzing the PIV data of the carrier fluid flow. Numerical simulations are juxtaposed with experimental data for prediction of the system's behavior.

  19. OFF-GAS MERCURY CONTROL USING SULFUR-IMPREGNATED ACTIVATED CARBON – TEST RESULTS

    SciTech Connect

    Nick Soelberg

    2007-05-01

    Several laboratory and pilot-scale tests since the year 2000 have included demonstrations of off-gas mercury control using fixed bed, sulfur-impregnated activated carbon. These demonstrations have included operation of carbon beds with gas streams containing a wide range of mercury and other gas species concentrations representing off-gas from several U.S. Department of Energy (DOE) mixed waste treatment processes including electrical resistance heated (joule-heated) glass melters, fluidized bed calciners, and fluidized bed steam reformers. Surrogates of various DOE mixed waste streams (or surrogates of offgas from DOE mixed waste streams) including INL “sodium bearing waste” (SBW), liquid “low activity waste” (LAW) from the Pacific Northwest National Laboratory, and liquid waste from Savannah River National Laboratory (“Tank 48H waste”) have been tested. Test results demonstrate mercury control efficiencies up to 99.999%, high enough to comply with the Hazardous Waste (HWC) Combustor Maximum Achievable Control Technology (MACT) standards even when the uncontrolled off-gas mercury concentrations exceed 400,000 ug/dscm (at 7% O2), and confirm carbon bed design parameters for such high efficiencies. Results of several different pilot-scale and engineering-scale test programs performed over several years are presented and compared.

  20. Preparation of activated carbon by chemical activation under vacuum.

    PubMed

    Juan, Yang; Ke-Qiang, Qiu

    2009-05-01

    Activated carbons especially used for gaseous adsorption were prepared from Chinesefir sawdust by zinc chloride activation under vacuum condition. The micropore structure, adsorption properties, and surface morphology of activated carbons obtained under atmosphere and vacuum were investigated. The prepared activated carbons were characterized by SEM, FTIR, and nitrogen adsorption. It was found that the structure of the starting material is kept after activation. The activated carbon prepared under vacuum exhibited higher values of the BET surface area (up to 1079 m2 g(-1)) and total pore volume (up to 0.5665 cm3 g(-1)) than those of the activated carbon obtained under atmosphere. This was attributed to the effect of vacuum condition that reduces oxygen in the system and limits the secondary reaction of the organic vapor. The prepared activated carbon has well-developed microstructure and high microporosity. According to the data obtained, Chinese fir sawdust is a suitable precursor for activated carbon preparation. The obtained activated carbon could be used as a low-cost adsorbent with favorable surface properties. Compared with the traditional chemical activation, vacuum condition demands less energy consumption, simultaneity, and biomass-oil is collected in the procedure more conveniently. FTIR analysis showed that heat treatment would result in the aromatization of the carbon structure. PMID:19534162

  1. An enigmatic source of hematitic carbonate beds containing vast amounts of iron oxidizers in a paleozoic metamorphic complex, South Hungary, Geresd-Hills, Ófalu.

    NASA Astrophysics Data System (ADS)

    Jáger, Viktor; Dabi, Gergely; Menyhárt, Adrienn

    2013-04-01

    Near the village of Ófalu, in the Geresd Hills, South Hungary, within the "Mecsekalja tectonic belt", low and intermediate grade paleozoic metamorphic complex (phyllite, gneiss) contains vein-like hematitic carbonate beds, up to 30 cm in thickness. The carbonate mineral is calcite. These hematitic carbonate beds cross-cut the foliation of the phyllite, and show no signs of any metamorphic alteration. In the studied section the red carbonate beds are associated with a vein system filled with multiple generations of vein carbonates(Dabi et al., 2011). The red carbonate beds contain a vaste number of twisted stalks of the iron oxidizing taxon of Gallionella. Rarely in some siliceous parts, Leptothrix-like microbial fossils can be found and these beds also contain numerous unidentifiable, hematitic foraminifers. According to ICP-AES measurements, the hematitic carbonate beds contains 8 % Fe, 0.86 % Mn and 0.12 % Ba. XRD and Raman measurements proved that the iron phase is hematite. The SEM observations revealed that the bacterial microfossils and foraminifers are built up of micron-submicron sized pseudohexagonal platy hematite. The bacterial microfossils of the Gallionella iron oxidizer are very well preserved and reaches about 80 µm length and about 2-3 µm width. The above observations raise the following issues: 1. how did these non metamorphic hematitic-carbonatic beds get inside into the metamorphic complex?, 2. what is the age of the formation of these beds?, and 3. what was the source of the iron? If we consider that the hematitic beds contain foraminifers and iron oxidizing bacteria, and no signs of metamorphic alteration nor foliations can be observed in these beds, the only answer for the first question is that the formations are fractures filled with lime-mud, i.e. neptunian dykes, which penetrated into the cracks of the phyllite. The presence of foraminifers and the geotectonic situation of the unit imply marine origin. Considering that these beds are

  2. Evaluation of fructooligosaccharides separation using a fixed-bed column packed with activated charcoal.

    PubMed

    Kuhn, Raquel Cristine; Mazutti, Marcio A; Albertini, Lilian Buoro; Filho, Francisco Maugeri

    2014-05-25

    Recent studies have shown that the chromatographic separation of mixtures of saccharides may be improved by making use of activated charcoal, a promising low cost material for the separation of sugars, including fructooligosaccharides. In this work, the development of a methodology to separate fructooligosaccharides from glucose, fructose and sucrose, using a fixed bed column packed with activated charcoal is proposed. The influence of temperature, eluant concentration and step gradients were evaluated to increase the separation efficiency and fructooligosaccharide purity. The final degree of fructooligosaccharide purification and separation efficiency were about 94% and 3.03 respectively, using ethanol gradient concentration ranging from 3.5% to 15% (v/v) at 40°C. The fixed bed column packed with the activated charcoal was shown to be a promising alternative for sugar separation, mainly those rich in fructooligosaccharides, leading to solutions of acceptable degrees of purification.

  3. Sorption of boron trifluoride by activated carbons

    SciTech Connect

    Polevoi, A.S.; Petrenko, A.E.

    1988-01-10

    The sorption of born trifluoride on AG-3, SKT, SKT-3, SKT-7, SKT-4A, SKT-6A, and SKT-2B carbons was investigated. The sorption isotherms for both vapors and gas were determined volumetrically. The coefficients of two equations described the sorption of BF/sub 3/ in the sorption of BF/sub 3/ on active carbons. Heats of sorption of BF/sub 3/ on the activated carbons are shown and the sorption isotherms and temperature dependences of the equilibrium pressure of BF/sub 3/ for activated carbons were presented. The values of the heats of sorption indicated the weak character of the reaction of BF/sub 3/ with the surface of the carbons. The equations can be used for calculating the phase equilibrium of BF/sub 3/ on carbons in a wider range of temperatures and pressures.

  4. A fluidized-bed continuous bioreactor for lactic acid production

    SciTech Connect

    Andrews, G.F.; Fonta, J.P.

    1988-05-01

    A laboratory bioreactor consists of a fluidized bed of monosized activated carbon coated with a biofilm of the homolactic fermentative organism Streptococcus thermophilus. Biofilm growth moves the carbon through the bed, and adsorption of substrate and product at the bottom and top of the bed respectively reduces their inhibitory effects on the organism. Theory shows that high reactor productivity and rapid recirculation of carbon through the bed require a biofilm thickness of 25 to 45% of the carbon particle radius on particles fed into the base of the bed. This could not be achieved in practice due to the fragility of the biofilm. Product concentration was higher than expected from measurements of product inhibition, possibly because it is the undissociated form of the acid that both inhibits metabolism and adsorbs on the activated carbon. The observed productivity of 12 gm/1 hr could be greatly increased by ph control. 13 refs., 7 figs., 2 tabs.

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

    SciTech Connect

    Abdullah, N.; Muhammad, I. S.; Hamid, S. B. Abd.; Rinaldi, A.; 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 deg. C for an hour in each step. The catalytic growth of nanocarbon in C{sub 2}H{sub 4}/H{sub 2} was carried out at temperature of 550 deg. C for 2 hrs with different rotating angle in the fluidization system. SEM and N{sub 2} 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.

  6. Carbon Limited Heterotrophic Activity in an Urban Stream

    NASA Astrophysics Data System (ADS)

    Hassett, B.; Bernhardt, E.; Palmer, M.

    2005-05-01

    Urban streams are characterized by flashy hydrographs, heavily incised channels, and scoured bed materials. Because of frequent scour, benthic organic matter in urban streams tends to be extremely low relative to nonurban streams. Recent research has related low organic matter availability to low rates of nitrogen uptake. We hypothesized that urban streams are carbon limited, and tested this hypothesis by adding a pulse of labile carbon (as potassium acetate) to the Stewart April tributary of Paint Branch, which drains a heavily urbanized watershed 73% impervious cover) in the suburbs of Washington, D.C. We predicted that the magnitude of the carbon effect on stream metabolism and N processing would be reduced as a result of litter inputs, and compared the stream response before and after peak litterfall. Adding labile dissolved organic carbon to the stream immediately increased metabolism in the stream channel during both additions, but this increase in heterotrophic activity did not lead to reductions in dissolved inorganic nitrogen concentrations. This indicates that while heterotrophs in this stream are carbon limited, the microbial community was not able to respond quickly enough to the pulse addition to appreciably reduce DIN concentrations in this eutrophic stream.

  7. International Space Station (ISS) Carbon Dioxide Removal Assembly (CDRA) Desiccant/Adsorbent Bed (DAB) Orbital Replacement Unit (ORU) Redesign

    NASA Technical Reports Server (NTRS)

    Reysa, Richard P.; Lumpkin, John P.; Sherif, Dian El; Kay, Robert; Williams, David E.

    2007-01-01

    The Carbon Dioxide Removal Assembly (CDRA) is a part of the International Space Station (ISS) Environmental Control and Life Support (ECLS) system. The CDRA provides carbon dioxide (CO2) removal from the ISS on-orbit modules. Currently, the CDRA is the secondary removal system on the ISS, with the primary system being the Russian Vozdukh. Within the CDRA are two desiccant/adsorbent beds (DAB), which perform the carbon dioxide removal function. The DAB adsorbent containment approach required improvements with respect to adsorbent containment. These improvements were implemented through a redesign program and have been implemented on units returning from orbit. This paper presents a DAB design modification implementation description, a hardware performance comparison between the unmodified and modified DAB configurations, and a description of the modified DAB hardware implementation into the on-orbit CDRA.

  8. 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

  9. The transport properties of activated carbon fibers

    SciTech Connect

    di Vittorio, S.L. . Dept. of Materials Science and Engineering); Dresselhaus, M.S. . Dept. of Electrical Engineering and Computer Science Massachusetts Inst. of Tech., Cambridge, MA . Dept. of Physics); Endo, M. . Dept. of Electrical Engineering); 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. 19 refs., 4 figs.

  10. 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.

  11. ACTIVATED CARBON FROM LIGNITE FOR WATER TREATMENT

    SciTech Connect

    Edwin S. Olson; Daniel J. Stepan

    2000-07-01

    High concentrations of humate in surface water result in the formation of excess amounts of chlorinated byproducts during disinfection treatment. These precursors can be removed in water treatment prior to disinfection using powdered activated carbon. In the interest of developing a more cost-effective method for removal of humates in surface water, a comparison of the activities of carbons prepared from North Dakota lignites with those of commercial carbons was conducted. Previous studies indicated that a commercial carbon prepared from Texas lignite (Darco HDB) was superior to those prepared from bituminous coals for water treatment. That the high alkali content of North Dakota lignites would result in favorable adsorptive properties for the very large humate molecules was hypothesized, owing to the formation of larger pores during activation. Since no standard humate test has been previously developed, initial adsorption testing was performed using smaller dye molecules with various types of ionic character. With the cationic dye, methylene blue, a carbon prepared from a high-sodium lignite (HSKRC) adsorbed more dye than the Darco HDB. The carbon from the low-sodium lignite was much inferior. With another cationic dye, malachite green, the Darco HDB was slightly better. With anionic dyes, methyl red and azocarmine-B, the results for the HSKRC and Darco HDB were comparable. A humate test was developed using Aldrich humic acid. The HSKRC and the Darco HDB gave equally high adsorption capacities for the humate (138 mg/g), consistent with the similarities observed in earlier tests. A carbon prepared from a high-sodium lignite from a different mine showed an outstanding improvement (201 mg/g). The carbons prepared from the low-sodium lignites from both mines showed poor adsorption capacities for humate. Adsorption isotherms were performed for the set of activated carbons in the humate system. These exhibited a complex behavior interpreted as resulting from two types

  12. Use of wood-based materials in beef bedded manure packs: 2. Effect on odorous volatile organic compounds, odor activity value, , and nutrient concentrations.

    PubMed

    Spiehs, Mindy J; Brown-Brandl, Tami M; Berry, Elaine D; Wells, James E; Parker, David B; Miller, Daniel N; Jaderborg, Jeffrey P; DiCostanzo, Alfred

    2014-07-01

    The objectives of this study were to determine the effects of three types of wood-based bedding materials (kiln-dried pine wood chips, dry cedar chips, and green cedar chips) and corn stover on the concentration of odorous volatile organic compounds (VOCs) and total in bedded pack material. Four bedded packs of each bedding material were maintained for two 42-d periods ( = 32; eight replicates/bedding material). Straight- and branched-chained fatty acids, aromatic compounds, and sulfide compounds were measured from the headspace above each bedded pack. Green cedar bedding had the highest concentration of odorous VOCs, and pine chip bedding had the lowest ( < 0.01). Calculated odor activity values were highest for green cedar bedding, followed by dry cedar, corn stover, and pine chip bedding. As the bedded packs aged, the concentration of odorous VOCs increased, particularly in the bedded packs containing green cedar chips and dry cedar chips. Total concentrations increased from Days 0 to 21 and then began to decline and were similar among all bedding materials ( < 0.10). Results of this study indicate that producers using a long-term bedded pack management in their facility may benefit from using pine chips because they do not appear to increase odor over time. Cedar-based bedding materials may be better suited for a scrape-and-haul system, where the bedded pack is removed after 1 or 2 wk. Total concentrations did not differ between any of the four bedding materials over time. PMID:25603068

  13. Performance evaluation of waste activated carbon on atrazine removal from contaminated water.

    PubMed

    Ghosh, Pranab Kumar; Philip, Ligy

    2005-01-01

    In this study, the potential of spent activated carbon from water purifier (Aqua Guard, India) for the removal of atrazine (2 chloro-4 ethylamino-6-isopropylamino-1, 3, 5 triazine) from wastewaters was evaluated. Different grades of spent activated carbon were prepared by various pretreatments. Based on kinetic and equilibrium study results, spent activated carbon with a grain size of 0.3-0.5 mm and washed with distilled water (designated as WAC) was selected for fixed column studies. Batch adsorption equilibrium data followed both Freundlich and Langmuir isotherm. Fixed bed adsorption column with spent activated carbon as adsorbent was used as a polishing unit for the removal of atrazine from the effluent of an upflow anaerobic sludge blanket (UASB) reactor treating atrazine bearing domestic wastewater. Growth of bacteria on the surface of WAC was observed during column study and bacterial activity enhanced the effectiveness of adsorbent on atrazine removal from wastewater. PMID:15913015

  14. Use of stable isotopes of carbon and nitrogen to identify sources of organic matter to bed sediments of the Tualatin River, Oregon

    USGS Publications Warehouse

    Bonn, Bernadine A.; Rounds, Stewart A.

    2010-01-01

    The potential sources of organic matter to bed sediment of the Tualatin River in northwestern Oregon were investigated by comparing the isotopic fractionation of carbon and nitrogen and the carbon/nitrogen ratios of potential sources and bed sediments. Samples of bed sediment, suspended sediment, and seston, as well as potential source materials, such as soil, plant litter, duckweed, and wastewater treatment facility effluent particulate were collected in 1998-2000. Based on the isotopic data, terrestrial plants and soils were determined to be the most likely sources of organic material to Tualatin River bed sediments. The delta 13C fractionation matched well, and although the delta 15N and carbon/nitrogen ratio of fresh plant litter did not match those of bed sediments, the changes expected with decomposition would result in a good match. The fact that the isotopic composition of decomposed terrestrial plant material closely resembled that of soils and bed sediments supports this conclusion. Phytoplankton probably was not a major source of organic matter to bed sediments. Compared to the values for bed sediments, the delta 13C values and carbon/nitrogen ratios of phytoplankton were too low and the delta 15N values were too high. Decomposition would only exacerbate these differences. Although phytoplankton cannot be considered a major source of organic material to bed sediment, a few bed sediment samples in the lower reach of the river showed a small influence from phytoplankton as evidenced by lower delta 13C values than in other bed sediment samples. Isotopic data and carbon/nitrogen ratios for bed sediments generally were similar throughout the basin, supporting the idea of a widespread source such as terrestrial material. The delta 15N was slightly lower in tributaries and in the upper reaches of the river. Higher rates of sediment oxygen demand have been measured in the tributaries in previous studies and coupled with the isotopic data may indicate the

  15. Adsorption of herbicides using activated carbons

    SciTech Connect

    Derbyshire, F.; Jagtoyen, M.; Lafferty, C.; Kimber, G.

    1996-12-31

    This paper describes the results of research in which novel activated carbons have been examined for their efficacy in water treatment and, specifically, for the adsorption of a common herbicide and wood preservative, sodium pentachlorophenolate. To place this work in context, the introduction will discuss first some of the considerations of using activated carbons for water treatment, and then certain aspects of the authors research that has led to this particular topic.

  16. FIXED-BED HYDROGENATION OF ORGANIC COMPOUNDS IN SUPERCRITICAL CARBON DIOXIDE. (R826034)

    EPA Science Inventory

    Abstract

    The Pd/C hydrogenation of cyclohexene to cyclohexane was performed in a continuous fixed-bed reactor employing CO2 to solubilize the reaction mixture in a single supercritical (sc) phase surrounding the solid catalyst. Employing an equimolar feed of...

  17. Direct determination and speciation of mercury compounds in environmental and biological samples by carbon bed atomic absorption spectroscopy

    SciTech Connect

    Skelly, E.M.

    1982-01-01

    A method was developed for the direct determination of mercury in water and biological samples using a unique carbon bed atomizer for atomic absorption spectroscopy. The method avoided sources of error such as loss of volatile mercury during sample digestion and contamination of samples through added reagents by eliminating sample pretreatment steps. The design of the atomizer allowed use of the 184.9 nm mercury resonance line in the vacuum ultraviolet region, which increased sensitivity over the commonly used spin-forbidden 253.7 nm line. The carbon bed atomizer method was applied to a study of mercury concentrations in water, hair, sweat, urine, blood, breath and saliva samples from a non-occupationally exposed population. Data were collected on the average concentration, the range and distribution of mercury in the samples. Data were also collected illustrating individual variations in mercury concentrations with time. Concentrations of mercury found were significantly higher than values reported in the literature for a ''normal'' population. This is attributed to the increased accuracy gained by eliminating pretreatment steps and increasing atomization efficiency. Absorption traces were obtained for various solutions of pure and complexed mercury compounds. Absorption traces of biological fluids were also obtained. Differences were observed in the absorption-temperatures traces of various compounds. The utility of this technique for studying complexation was demonstrated.

  18. A model to predict the adsorber thermal behavior during treatment of volatile organic compounds onto wet activated carbon.

    PubMed

    Pré, P; Delage, F; Le Cloirec, P

    2002-11-01

    A model for adsorption of volatile organic compounds (VOCs) onto a wet activated carbon bed was proposed in this study. This model accounts for temperature changes induced by the reversed and coupled mass-transfer processes of both organic species adsorption and water desorption. Indeed, it was experimentally pointed out that temperature rises, which result from the exothermal nature of the energetic interactions between the organic molecule and the activated carbon surface, are notably reduced when the adsorbent contains an initial moisture of approximately 10% in weight. Moreover, it was shown that water rate desorption was enhanced in the presence of organic vapor. This phenomenon may be explained by the displacement of sorbed water bythe organic molecules, owing to more intensive interactions with the activated carbon surface. The model proposed was elaborated from a previous comprehensive analysis of the diffusion mechanisms governing VOC adsorption at high concentrations onto a dry activated carbon bed. In a similar way, a theoretical approach was developed to model water desorption during drying of a wet activated carbon bed under pure flowing air. At last, a theoretical depiction of both competitive and reverse processes was outlined. The final model fits reasonably with experimental data relative to both breakthrough curves and thermal wave shape along the bed, even if local temperature change calculation may require some further improvement.

  19. 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.

  20. Adsorption of methyl mercaptan on activated carbons.

    PubMed

    Bashkova, Svetlana; Bagreev, Andrey; Bandosz, Teresa J

    2002-06-15

    Activated carbons of different origins were studied as methyl mercaptan adsorbents in wet, dry, and oxidizing conditions. The materials were characterized using adsorption of nitrogen, Boehm titration, and thermal analysis. Investigation was focused on the feasibility of the removal of methyl mercaptan on activated carbons and on the role of surface chemistry and porosity in the adsorption/oxidation processes. The results showed relatively high capacities of carbons for removal of CH3SH. The amount adsorbed depends on the surface features. Methyl mercaptan, in general, is oxidized to disulfides, which, depending on the chemistry of the carbon surface, can be converted to sulfonic acid due to the presence of water and active radicals.

  1. Activation of Canadian coals in a fixed-bed reactor: effect of the particle size on product quality

    SciTech Connect

    Ajay K. Dalai; Narayan C. Pradhan; Jian Liu; Amitabha Majumdar; Eric L. Tollefson

    2008-07-15

    Three Canadian coals, namely, Bienfait lignite, Montgomery sub-bituminous C, and Coal Valley high volatile bituminous C were activated in a fixed-bed reactor. For each coal, two different sizes of particles in the ranges of 0-1.25 mm (fines) and 1.25-2.5 mm (granules) along with cylindrical pellets of 3.18 mm in diameter and 7{+-}2 mm long were activated. The qualities of the products were determined by measuring iodine and methylene blue numbers, specific Brunauer-Emmett-Teller (BET) surface areas, bulk densities, and ash contents. The specific surface areas and iodine and methylene blue numbers of bituminous coal products were lower than the values obtained with the lignite and sub-bituminous coals, although the product yields were higher. Products obtained from pellets were found to have superior quality compared to that obtained from fines. The ash content of the feed coal influences the quality of the product activated carbon. It was established that a first-order reaction between steam and coal pellets occurred in the process. The activation energies for the process were also determined. 17 refs., 12 figs., 4 tabs.

  2. Antimicrobial Activity of Carbon-Based Nanoparticles

    PubMed Central

    Maleki Dizaj, Solmaz; Mennati, Afsaneh; Jafari, Samira; Khezri, Khadejeh; Adibkia, Khosro

    2015-01-01

    Due to the vast and inappropriate use of the antibiotics, microorganisms have begun to develop resistance to the commonly used antimicrobial agents. So therefore, development of the new and effective antimicrobial agents seems to be necessary. According to some recent reports, carbon-based nanomaterials such as fullerenes, carbon nanotubes (CNTs) (especially single-walled carbon nanotubes (SWCNTs)) and graphene oxide (GO) nanoparticles show potent antimicrobial properties. In present review, we have briefly summarized the antimicrobial activity of carbon-based nanoparticles together with their mechanism of action. Reviewed literature show that the size of carbon nanoparticles plays an important role in the inactivation of the microorganisms. As major mechanism, direct contact of microorganisms with carbon nanostructures seriously affects their cellular membrane integrity, metabolic processes and morphology. The antimicrobial activity of carbon-based nanostructures may interestingly be investigated in the near future owing to their high surface/volume ratio, large inner volume and other unique chemical and physical properties. In addition, application of functionalized carbon nanomaterials as carriers for the ordinary antibiotics possibly will decrease the associated resistance, enhance their bioavailability and provide their targeted delivery. PMID:25789215

  3. Microwave-assisted regeneration of activated carbon.

    PubMed

    Foo, K Y; Hameed, B H

    2012-09-01

    Microwave heating was used in the regeneration of methylene blue-loaded activated carbons produced from fibers (PFAC), empty fruit bunches (EFBAC) and shell (PSAC) of oil palm. The dye-loaded carbons were treated in a modified conventional microwave oven operated at 2450 MHz and irradiation time of 2, 3 and 5 min. The virgin properties of the origin and regenerated activated carbons were characterized by pore structural analysis and nitrogen adsorption isotherm. The surface chemistry was examined by zeta potential measurement and determination of surface acidity/basicity, while the adsorptive property was quantified using methylene blue (MB). Microwave irradiation preserved the pore structure, original active sites and adsorption capacity of the regenerated activated carbons. The carbon yield and the monolayer adsorption capacities for MB were maintained at 68.35-82.84% and 154.65-195.22 mg/g, even after five adsorption-regeneration cycles. The findings revealed the potential of microwave heating for regeneration of spent activated carbons.

  4. Nitrate removal, communities of denitrifiers and adverse effects in different carbon substrates for use in denitrification beds.

    PubMed

    Warneke, Sören; Schipper, Louis A; Matiasek, Michael G; Scow, Kate M; Cameron, Stewart; Bruesewitz, Denise A; McDonald, Ian R

    2011-11-01

    Denitrification beds are containers filled with wood by-products that serve as a carbon and energy source to denitrifiers, which reduce nitrate (NO(3)(-)) from point source discharges into non-reactive dinitrogen (N(2)) gas. This study investigates a range of alternative carbon sources and determines rates, mechanisms and factors controlling NO(3)(-) removal, denitrifying bacterial community, and the adverse effects of these substrates. Experimental barrels (0.2 m(3)) filled with either maize cobs, wheat straw, green waste, sawdust, pine woodchips or eucalyptus woodchips were incubated at 16.8 °C or 27.1 °C (outlet temperature), and received NO(3)(-) enriched water (14.38 mg N L(-1) and 17.15 mg N L(-1)). After 2.5 years of incubation measurements were made of NO(3)(-)-N removal rates, in vitro denitrification rates (DR), factors limiting denitrification (carbon and nitrate availability, dissolved oxygen, temperature, pH, and concentrations of NO(3)(-), nitrite and ammonia), copy number of nitrite reductase (nirS and nirK) and nitrous oxide reductase (nosZ) genes, and greenhouse gas production (dissolved nitrous oxide (N(2)O) and methane), and carbon (TOC) loss. Microbial denitrification was the main mechanism for NO(3)(-)-N removal. Nitrate-N removal rates ranged from 1.3 (pine woodchips) to 6.2 g N m(-3) d(-1) (maize cobs), and were predominantly limited by C availability and temperature (Q(10) = 1.2) when NO(3)(-)-N outlet concentrations remained above 1 mg L(-1). The NO(3)(-)-N removal rate did not depend directly on substrate type, but on the quantity of microbially available carbon, which differed between carbon sources. The abundance of denitrifying genes (nirS, nirK and nosZ) was similar in replicate barrels under cold incubation, but varied substantially under warm incubation, and between substrates. Warm incubation enhanced growth of nirS containing bacteria and bacteria that lacked the nosZ gene, potentially explaining the greater N(2)O emission in

  5. 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.

  6. Upgrading the rice husk char obtained by flash pyrolysis for the production of amorphous silica and high quality activated carbon.

    PubMed

    Alvarez, Jon; Lopez, Gartzen; Amutio, Maider; Bilbao, Javier; Olazar, Martin

    2014-10-01

    The overall valorization of rice husk char obtained by flash pyrolysis in a conical spouted bed reactor (CSBR) has been studied in a two-step process. Thus, silica has been recovered in a first step and the remaining carbon material has been subjected to steam activation. The char samples used in this study have been obtained by continuous flash pyrolysis in a conical spouted bed reactor at 500°C. Extraction with Na2CO3 allows recovering 88% of the silica contained in the rice husk char. Activation of the silica-free rice husk char has been carried out in a fixed bed reactor at 800°C using steam as activating agent. The porous structure of the activated carbons produced includes a combination of micropores and mesopores, with a BET surface area of up to 1365m(2)g(-1) at the end of 15min.

  7. TREATMENT OF VOCS IN HIGH STRENGTH WASTES USING AN ANAEROBIC EXPANDED-BED GAS REACTOR

    EPA Science Inventory

    The potential of the expanded-bed granular activated carbon (GAC) anaerobic reactor in treating a high strength waste containing RCRA volatile organic compounds (VOCs) was studied. A total of six VOCs, methylene chloride, chlorobenzene, carbon tetrachloride, chloroform, toluene ...

  8. Impacts of backwashing on granular activated carbon filters for advanced wastewater treatment.

    PubMed

    Frank, Joshua; Ruhl, Aki Sebastian; Jekel, Martin

    2015-12-15

    The use of granular activated carbon (GAC) in fixed bed filters is a promising option for the removal of organic micropollutants (OMP) from wastewater treatment plant effluents. Frequent backwashing of the filter bed is inevitable, but its effect on potential filter stratification is not well understood yet and thus has been evaluated in the present study for two commercial GAC products. Backwashing of GAC filters was simulated with 10 or 100 filter bed expansions of 20 or 100% at backwash velocities of 12 and 40 m/h, respectively. Five vertical fractions were extracted and revealed a vertical stratification according to grain sizes and material densities. Sieve analyses indicated increasing grain sizes towards the bottom for one GAC while grain sizes of the other GAC were more homogeneously distributed throughout the filter bed. The apparent densities of the top sections were significantly lower than that of the bottom sections of both products. Comparative long term fixed bed adsorption experiments with the top and bottom sections of the stratified GAC showed remarkable differences in breakthrough curves of dissolved organic carbon, UV light absorption at 254 nm wavelength (UVA254) and OMP. GAC from the upper section showed constantly better removal efficiencies than GAC from the bottom section, especially for weakly adsorbing OMP such as sulfamethoxazole. Furthermore correlations between UVA254 reductions and OMP removals were found.

  9. Impacts of backwashing on granular activated carbon filters for advanced wastewater treatment.

    PubMed

    Frank, Joshua; Ruhl, Aki Sebastian; Jekel, Martin

    2015-12-15

    The use of granular activated carbon (GAC) in fixed bed filters is a promising option for the removal of organic micropollutants (OMP) from wastewater treatment plant effluents. Frequent backwashing of the filter bed is inevitable, but its effect on potential filter stratification is not well understood yet and thus has been evaluated in the present study for two commercial GAC products. Backwashing of GAC filters was simulated with 10 or 100 filter bed expansions of 20 or 100% at backwash velocities of 12 and 40 m/h, respectively. Five vertical fractions were extracted and revealed a vertical stratification according to grain sizes and material densities. Sieve analyses indicated increasing grain sizes towards the bottom for one GAC while grain sizes of the other GAC were more homogeneously distributed throughout the filter bed. The apparent densities of the top sections were significantly lower than that of the bottom sections of both products. Comparative long term fixed bed adsorption experiments with the top and bottom sections of the stratified GAC showed remarkable differences in breakthrough curves of dissolved organic carbon, UV light absorption at 254 nm wavelength (UVA254) and OMP. GAC from the upper section showed constantly better removal efficiencies than GAC from the bottom section, especially for weakly adsorbing OMP such as sulfamethoxazole. Furthermore correlations between UVA254 reductions and OMP removals were found. PMID:26405842

  10. Occurrence and morphology of carbonate concretions in the Beulah-Zap coal bed, Williston basin, North Dakota

    USGS Publications Warehouse

    Keighin, C.W.M.; Flores, R.M.; Rowland, T.

    1996-01-01

    Carbonate concretionary bodies were encountered during mining of the Beulah-Zap lignite seam in the Coteau Properties' Freedom mine, Mercer County, North Dakota. Preliminary studies show that areal and vertical distribution of the concretions are variable. All concretions examined are composed almost entirely of calcite. They occur as thin tabular bodies, as more or less elliptical forms, or as tear shaped bodies, and may occur individually or as clusters of buff-colored, poorly consolidated to solidly crystalline material. The carbonate masses vary in size from a few millimeters to tens of centimeters. Bedding in the lignite may display some compactional folding over dense spheroidal to elliptical concretions, indicating formation of the concretions prior to compaction. Internal morphology of the concretions is complex, and includes cone-in-cone structure, cross-cutting calcite veinlets, and multiple generations of calcite. Carbon isotope values suggest the concretions are composed of biogenic carbonate, probably related to early diagenesis and decomposition of organic matter (peat); oxygen isotope values are light, and consistent with a freshwater origin.

  11. The relative contribution of methanotrophs to microbial communities and carbon cycling in soil overlying a coal-bed methane seep

    USGS Publications Warehouse

    Mills, Christopher T.; Slater, Gregory F.; Dias, Robert F.; Carr, Stephanie A.; Reddy, Christopher M.; Schmidt, Raleigh; Mandernack, Kevin W.

    2013-01-01

    Seepage of coal-bed methane (CBM) through soils is a potential source of atmospheric CH4 and also a likely source of ancient (i.e. 14C-dead) carbon to soil microbial communities. Natural abundance 13C and 14C compositions of bacterial membrane phospholipid fatty acids (PLFAs) and soil gas CO2 and CH4 were used to assess the incorporation of CBM-derived carbon into methanotrophs and other members of the soil microbial community. Concentrations of type I and type II methanotroph PLFA biomarkers (16:1ω8c and 18:1ω8c, respectively) were elevated in CBM-impacted soils compared with a control site. Comparison of PLFA and 16s rDNA data suggested type I and II methanotroph populations were well estimated and overestimated by their PLFA biomarkers, respectively. The δ13C values of PLFAs common in type I and II methanotrophs were as negative as −67‰ and consistent with the assimilation of CBM. PLFAs more indicative of nonmethanotrophic bacteria had δ13C values that were intermediate indicating assimilation of both plant- and CBM-derived carbon. Δ14C values of select PLFAs (−351 to −936‰) indicated similar patterns of CBM assimilation by methanotrophs and nonmethanotrophs and were used to estimate that 35–91% of carbon assimilated by nonmethanotrophs was derived from CBM depending on time of sampling and soil depth.

  12. Least cost process design for granular activated carbon adsorbers

    SciTech Connect

    Narbaitz, R.M.; Benedek, A.

    1983-10-01

    Although toxic organics may be removed from industrial effluents by activated carbon adsorbers, the cost of this process is relatively high. Also, adsorber design is complex because of the unsteady-state nature of the process and the numerous operational variables. A package of computer programs has been developed to help to minimise the ultimate cost of 4 types of column configurations. It determines the effect of treatment facility costs of different values for design and operational variables, such as empty bed contact time (EBCT), hydraulic loading, and column configurations. The results of a sample problem indicated that the optimum EBCT for all the column configurations was significantly higher than values typically used by designers.

  13. Carbonate cements and grains in submarine fan sandstones—the Cergowa Beds (Oligocene, Carpathians of Poland) recorded by cathodoluminescence

    NASA Astrophysics Data System (ADS)

    Pszonka, Joanna; Wendorff, Marek

    2016-03-01

    The cathodoluminescence (CL) observations with cold cathode, supplemented by reconnaissance scanning electron microscope analyses, bring new data on petrology, provenance and diagenesis of the Oligocene-age Cergowa sandstones from the Outer Carpathians (SE Poland). The sandstones represent a variety of mass gravity flow sediments deposited on a submarine fan, which now forms a lenticular lithosome—a part of the Menilite Beds-Krosno Beds suite important for the hydrocarbons industry. The most common components of the Cergowa sandstones observed under the CL are carbonates—cement and grains that are mainly represented by lithoclasts. Carbonate cement is represented by five generations: brown (Cb), orange (Co), yellow (Cy), zoned (Cz) and black (Ck). Pore-filling Cb and Co calcite cements are interpreted as genetically related to eo- and mesodiagenetic phases. The mesodiagenetic phase is characterised by randomly distributed relatively large monocrystalline-zoned rhombs of dolomite cement (Cz) and ankerite/ferroan dolomite (Ck). The telodiagenetic phase is represented by pore-filling yellow calcite (Cy) that crystallised under the influence of suboxic meteoric waters. Lithoclasts represent six microfacies of carbonate rocks eroded in the source area, i.e. microbreccia, tectonised immature calcarenite/wacke, microsparite, sparite, biomicrosparite/packstone and dolostone. Pronounced indentations of terrigenous sand grains into intraclasts of packstone/biomicrosparite, coupled with commonly present similar packstone-type matrix, suggest that a significant part of matrix resulted from compaction of soft biomicrosparite grains. Terrigenous grains bound by calcite cement are commonly corroded by acidic diagenetic fluids, and partial or even complete replacement of silicates by calcite and clay minerals is illustrated here by feldspar grains. Substantial carbonate cementation has resulted in both the significant hardness and abrasion resistance of the Cergowa sandstones

  14. Nanofiltration and granular activated carbon treatment of perfluoroalkyl acids.

    PubMed

    Appleman, Timothy D; Dickenson, Eric R V; Bellona, Christopher; Higgins, Christopher P

    2013-09-15

    Perfluoroalkyl acids (PFAAs) are of concern because of their persistence in the environment and the potential toxicological effects on humans exposed to PFAAs through a variety of possible exposure routes, including contaminated drinking water. This study evaluated the efficacy of nanofiltration (NF) and granular activated carbon (GAC) adsorption in removing a suite of PFAAs from water. Virgin flat-sheet NF membranes (NF270, Dow/Filmtec) were tested at permeate fluxes of 17-75 Lm(-2)h(-1) using deionized (DI) water and artificial groundwater. The effects of membrane fouling by humic acid on PFAA rejection were also tested under constant permeate flux conditions. Both virgin and fouled NF270 membranes demonstrated >93% removal for all PFAAs under all conditions tested. GAC efficacy was tested using rapid small-scale columns packed with Calgon Filtrasorb300 (F300) carbon and DI water with and without dissolved organic matter (DOM). DOM effects were also evaluated with F600 and Siemens AquaCarb1240C. The F300 GAC had <20% breakthrough of all PFAAs in DI water for up to 125,000 bed volumes (BVs). When DOM was present, >20% breakthrough of all PFAAs by 10,000 BVs was observed for all carbons.

  15. Kinetics of salicylic acid adsorption on activated carbon.

    PubMed

    Polakovic, Milan; Gorner, Tatiana; Villiéras, Frédéric; de Donato, Philippe; Bersillon, Jean Luc

    2005-03-29

    The adsorption and desorption of salicylic acid from water solutions was investigated in HPLC microcolumns packed with activated carbon. The adsorption isotherm was obtained by the step-up frontal analysis method in a concentration range of 0-400 mg/L and was well fitted with the Langmuir equation. The investigation of rate aspects of salicylic acid adsorption was based on adsorption/desorption column experiments where different inlet concentrations of salicylic acid were applied in the adsorption phase and desorption was conducted with pure water. The concentration profiles of individual adsorption/desorption cycles data were fitted using several single-parameter models of the fixed-bed adsorption to assess the influence of different phenomena on the column behavior. It was found that the effects of axial dispersion and extraparticle mass transfer were negligible. A rate-determining factor of fixed-bed column dynamics was the kinetics of pore surface adsorption. A bimodal kinetic model reflecting the heterogeneous character of adsorbent pores was verified by a simultaneous fit of the column outlet concentration in four adsorption/desorption cycles. The fitted parameters were the fraction of mesopores and the adsorption rate constants in micropores and mesopores, respectively. It was shown that the former rate constant was an intrinsic one whereas the latter one was an apparent value due to the effects of pore blocking and diffusional hindrances in the micropores. PMID:15779975

  16. Supporting the process of removing humic substances on activated carbon.

    PubMed

    Olesiak, Paulina; Stępniak, Longina

    2014-01-01

    This study is focused on biosorption process used in water treatment. The process has a number of advantages and a lot of research has been done into its intensification by means of ultrasonic modification of solutions. The study carried out by the authors leads to the conclusion that sonication of organic solutions allows for extension of the time of operation of carbon beds. For the analysis of the results obtained during the sorption of humic substances (HS) from the solution dependencies UV/UV₀ or DOC/DOC₀ were used. In comparative studies the effectiveness of sorption and sonosorption (UV/UV₀) shows that the share of ultrasounds (US) is beneficial for extension of time deposit, both at a flow rate HS solution equal to 1 m/h and 5 m/h. Analysis of the US impact sorption on HS sorption in a biological fluidized bed, both prepared from biopreparat and the activated sludge confirms the higher efficiency compared to sonobiosorption than biosorption. These results confirm the degree of reduction UV₂₅₄/UV₀ and DOC/DOC₀ for the same processes. EMS index also confirms the improvement of HSbiodegradation by sludge microorganisms.

  17. Removal of bromate and assimilable organic carbon from drinking water using granular activated carbon.

    PubMed

    Huang, W J; Peng, H S; Peng, M Y; Chen, L Y

    2004-01-01

    This study investigated the feasibility of using granular activated carbon (GAC) to remove bromate ion (BrO3-) and assimilable organic carbon (AOC) from drinking water through a rapid small-scale column test (RSSCT) method and a pilot-scale study. Results from RSSCT indicated that the GAC capacity for BrO3- removal was dependent on the GAC type, empty bed contact time (EBCT), and source water quality. The GAC with a high number of basic groups and higher pHpzc values showed an increased BrO3- removal capacity. BrO3- removal was improved by increasing EBCT. The high EBCT provides a greater opportunity for BrO3- to be adsorbed and reduced to Br- on the GAC surface. On the other hand, the presence of dissolved organic carbon (DOC) and anions, such as chloride, bromide, and sulfate, resulted in poor BrO3- reduction. In the GAC pilot plant, a GAC column preloaded for 12 months achieved a BrO3- and AOC removal range from 79-96% and 41-75%, respectively. The BrO3- amount removed was found to be proportional to the influent BrO3- concentration. However, the BrO3- removal rate apparently decreased with increasing operation time. In contrast, the AOC apparently increased during the long-term operation period. This may be a result of the contribution due to new GAC being gradually transformed into biological activated carbon (BAC), and the bacterial biomass adsorbed on GAC surface hindering BrO3- reduction by GAC either by blocking pores or adsorbing at the activated sites for BrO3- reduction. PMID:15566189

  18. Updated Performance Evaluation of the ISS Water Processor Multifiltration Beds

    NASA Technical Reports Server (NTRS)

    Bowman, Elizabeth M.; Carter, Layne; Carpenter, Joyce; Orozco, Nicole; Weir, Natalee; Wilson, Mark

    2014-01-01

    The ISS Water Processor Assembly (WPA) produces potable water from a waste stream containing humidity condensate and urine distillate. The primary treatment process is achieved in the Multifiltration Beds, which include adsorbent media and ion exchange resin for the removal of dissolved organic and inorganic contaminants. Two Multifiltration Beds (MF Beds) were replaced on ISS in July 2010 after initial indication of inorganic breakthrough of the first bed and an increasing Total Organic Carbon (TOC) trend in the product water. The first bed was sampled and analyzed Sept 2011 through March 2012. The second MF Bed was sampled and analyzed June 2012 through August 2012. The water resident in the both beds was analyzed for various parameters to evaluate adsorbent loading, performance of the ion exchange resin, microbial activity, and generation of leachates from the ion exchange resin. Portions of the adsorbent media and ion exchange resin were sampled and subsequently desorbed to identify the primary contaminants removed at various points in the bed in addition to microbial analysis. Analysis of the second bed will be compared to results from the first bed to provide a comprehensive overview of how the Multifiltration Beds function on orbit. New data from the second bed supplements the analysis of the first bed (previously reported) and gives a more complete picture of breakthrough compounds, resin breakdown products, microbial activity, and difficult to remove compounds. The results of these investigations and implications to the operation of the WPA on ISS are documented in this paper.

  19. A novel activated carbon for supercapacitors

    SciTech Connect

    Shen, Haijie; Liu, Enhui; Xiang, Xiaoxia; Huang, Zhengzheng; Tian, Yingying; Wu, Yuhu; Wu, Zhilian; Xie, Hui

    2012-03-15

    Highlights: Black-Right-Pointing-Pointer A novel activated carbon was prepared from phenol-melamine-formaldehyde resin. Black-Right-Pointing-Pointer The carbon has large surface area with microporous, and high heteroatom content. Black-Right-Pointing-Pointer Heteroatom-containing functional groups can improve the pseudo-capacitance. Black-Right-Pointing-Pointer Physical and chemical properties lead to the good electrochemical properties. -- Abstract: A novel activated carbon has been prepared by simple carbonization and activation of phenol-melamine-formaldehyde resin which is synthesized by the condensation polymerization method. The morphology, thermal stability, surface area, elemental composition and surface chemical composition of samples have been investigated by scanning electron microscope, thermogravimetry and differential thermal analysis, Brunauer-Emmett-Teller measurement, elemental analysis and X-ray photoelectron spectroscopy, respectively. Electrochemical properties have been studied by cyclic voltammograms, galvanostatic charge/discharge, and electrochemical impedance spectroscopy measurements in 6 mol L{sup -1} potassium hydroxide. The activated carbon shows good capacitive behavior and the specific capacitance is up to 210 F g{sup -1}, which indicates that it may be a promising candidate for supercapacitors.

  20. OZONE REACTION WITH N-ALDEHYDES (N=4-10), BENZALDEHYDE, ETHANOL, ISOPROPANOL, AND N-PROPANOL ADSORBED ON A DUAL-BED GRAPHITIZED CARBON/CARBON MOLECULAR SIEVE ADSORBENT CARTRIDGE

    EPA Science Inventory

    Ozone reacts with n-aldehydes (n = 4 - 10), benzaldehyde, ethanol, isopropanol, and n-propanol adsorbed on a dual-bed graphitized carbon/carbon molecular sieve adsorbent cartridge. Destruction of n-aldehydes increases with n number and with ozone concentration. In some samp...

  1. Biomechanics-based active control of bedding support properties and its influence on sleep.

    PubMed

    Van Deun, D; Verhaert, V; Willemen, T; Wuyts, J; Verbraecken, J; Exadaktylos, V; Haex, B; Vander Sloten, J

    2012-01-01

    Proper body support plays an import role in the recuperation of our body during sleep. Therefore, this study uses an automatically adapting bedding system that optimises spinal alignment throughout the night by altering the stiffness of eight comfort zones. The aim is to investigate the influence of such a dynamic sleep environment on objective and subjective sleep parameters. The bedding system contains 165 sensors that measure mattress indentation. It also includes eight actuators that control the comfort zones. Based on the measured mattress indentation, body movements and posture changes are detected. Control of spinal alignment is established by fitting personalized human models in the measured indentation. A total of 11 normal sleepers participated in this study. Sleep experiments were performed in a sleep laboratory where subjects slept three nights: a first night for adaptation, a reference night and an active support night (in counterbalanced order). Polysomnographic measurements were recorded during the nights, combined with questionnaires aiming at assessing subjective information. Subjective information on sleep quality, daytime quality and perceived number of awakenings shows significant improvements during the active support (ACS) night. Objective results showed a trend towards increased slow wave sleep. On the other hand, it was noticed that % N1-sleep was significantly increased during ACS night, while % N2-sleep was significantly decreased. No prolonged N1 periods were found during or immediately after steering.

  2. Ex Situ CO2 capture by carbonation of steelmaking slag coupled with metalworking wastewater in a rotating packed bed.

    PubMed

    Pan, Shu-Yuan; Chiang, Pen-Chi; Chen, Yi-Hung; Tan, Chung-Sung; Chang, E-E

    2013-04-01

    Both basic oxygen furnace (BOF) slag and cold-rolling wastewater (CRW) exhibiting highly alkaline characteristics require stabilization and neutralization prior to utilization and/or final disposal. Using CO2 from flue gases as the stabilizing and neutralizing agents could also diminish CO2 emissions. In this investigation, ex situ hot stove gas containing 30 vol% CO2 in the steelmaking process was captured by accelerated carbonation of BOF slag coupled with CRW in a rotating packed bed (RPB). The developed RPB process exhibits superior results, with significant CO2 removal efficiency (η) of 96-99% in flue gas achieved within a short reaction time of 1 min at 25 °C and 1 atm. Calcite (CaCO3) was identified as the main product according to XRD and SEM-XEDS observations. In addition, the elimination of lime and Ca(OH)2 in the BOF slag during carbonation is beneficial to its further use as construction material. Consequently, the developed RPB process could capture the CO2 from the flue gas, neutralize the CRW, and demonstrate the utilization potential for BOF slag. It was also concluded that carbonation of BOF slag coupled with CRW in an RPB is a viable method for CO2 capture due to its higher mass transfer rate and CO2 removal efficiency in a short reaction time. PMID:23458276

  3. Treatment of sludge containing nitro-aromatic compounds in reed-bed mesocosms - Water, BOD, carbon and nutrient removal.

    PubMed

    Gustavsson, L; Engwall, M

    2012-01-01

    Since the mid-1970s, Sweden has been depositing 1 million ton d.w sludge/year, produced at waste water treatment plants. Due to recent legislation this practice is no longer a viable method of waste management. It is necessary to improve existing and develop new sludge management techniques and one promising alternative is the dewatering and treatment of sludge in constructed wetlands. The aim of this study was to follow reduction of organic carbon, BOD and nutrients in an industrial sludge containing nitro-aromatic compounds passing through constructed small-scale wetlands, and to investigate any toxic effect such as growth inhibition of the common reed Phragmites australis. The result showed high reduction of all tested parameters in all the outgoing water samples, which shows that constructed wetlands are suitable for carbon and nutrient removal. The results also showed that P. australis is tolerant to xenobiotics and did not appear to be affected by the toxic compounds in the sludge. The sludge residual on the top of the beds contained low levels of organic carbon and is considered non-organic and could therefore be landfilled. Using this type of secondary treatment method, the amount of sludge could be reduced by 50-70%, mainly by dewatering and biodegradation of organic compounds. PMID:21944874

  4. Treatment of sludge containing nitro-aromatic compounds in reed-bed mesocosms - Water, BOD, carbon and nutrient removal.

    PubMed

    Gustavsson, L; Engwall, M

    2012-01-01

    Since the mid-1970s, Sweden has been depositing 1 million ton d.w sludge/year, produced at waste water treatment plants. Due to recent legislation this practice is no longer a viable method of waste management. It is necessary to improve existing and develop new sludge management techniques and one promising alternative is the dewatering and treatment of sludge in constructed wetlands. The aim of this study was to follow reduction of organic carbon, BOD and nutrients in an industrial sludge containing nitro-aromatic compounds passing through constructed small-scale wetlands, and to investigate any toxic effect such as growth inhibition of the common reed Phragmites australis. The result showed high reduction of all tested parameters in all the outgoing water samples, which shows that constructed wetlands are suitable for carbon and nutrient removal. The results also showed that P. australis is tolerant to xenobiotics and did not appear to be affected by the toxic compounds in the sludge. The sludge residual on the top of the beds contained low levels of organic carbon and is considered non-organic and could therefore be landfilled. Using this type of secondary treatment method, the amount of sludge could be reduced by 50-70%, mainly by dewatering and biodegradation of organic compounds.

  5. Ex Situ CO2 capture by carbonation of steelmaking slag coupled with metalworking wastewater in a rotating packed bed.

    PubMed

    Pan, Shu-Yuan; Chiang, Pen-Chi; Chen, Yi-Hung; Tan, Chung-Sung; Chang, E-E

    2013-04-01

    Both basic oxygen furnace (BOF) slag and cold-rolling wastewater (CRW) exhibiting highly alkaline characteristics require stabilization and neutralization prior to utilization and/or final disposal. Using CO2 from flue gases as the stabilizing and neutralizing agents could also diminish CO2 emissions. In this investigation, ex situ hot stove gas containing 30 vol% CO2 in the steelmaking process was captured by accelerated carbonation of BOF slag coupled with CRW in a rotating packed bed (RPB). The developed RPB process exhibits superior results, with significant CO2 removal efficiency (η) of 96-99% in flue gas achieved within a short reaction time of 1 min at 25 °C and 1 atm. Calcite (CaCO3) was identified as the main product according to XRD and SEM-XEDS observations. In addition, the elimination of lime and Ca(OH)2 in the BOF slag during carbonation is beneficial to its further use as construction material. Consequently, the developed RPB process could capture the CO2 from the flue gas, neutralize the CRW, and demonstrate the utilization potential for BOF slag. It was also concluded that carbonation of BOF slag coupled with CRW in an RPB is a viable method for CO2 capture due to its higher mass transfer rate and CO2 removal efficiency in a short reaction time.

  6. Improvement of heat transfer in a packed-bed reactor for a chemical heat pump using sodium carbonate decahydrate dehydration

    SciTech Connect

    Matsumura, Yukihiko; Yoshida, Kunio

    1997-06-01

    To improve the heat transfer characteristics of a gas-solid packed-bed reactor, an inert solvent was added to the reactor. For sodium carbonate decahydrate dehydration, used in a chemical heat pump, n-pentanol was chosen as a solvent, and the dehydration rate in the solvent was measured. The dehydration rate was found to be proportional to the total surface area of the decahydrate particles, and the rate equation was determined. Particle size distribution (less than 400 {micro}m) remained unchanged for a three-time cyclic operation. The packed-bed of decahydrate with n-pentanol solvent showed considerable improvement in heat transfer characteristics compared with the case having no solvent, and cold heat generation was more than doubled. A simulation study showed that the addition of n-pentanol may make it possible to construct a high-performance heat pump with cold storage capability, attaining 280 K in less than 5 s and total heat release within 1,600 s.

  7. Evaluation of alkanolamine solutions for carbon dioxide removal in cross-flow rotating packed beds.

    PubMed

    Lin, Chia-Chang; Lin, Yu-Hong; Tan, Chung-Sung

    2010-03-15

    The removal of CO(2) from a 10 vol% CO(2) gas by chemical absorption with 30 wt% alkanolamine solutions containing monoethanolamine (MEA), piperazine (PZ), and 2-amino-2-methyl-1-propanol (AMP) in the cross-flow rotating packed bed (RPB) was investigated. The CO(2) removal efficiency increased with rotor speed, liquid flow rate and inlet liquid temperature. However, the CO(2) removal efficiency decreased with gas flow rate. Also, the CO(2) removal efficiency was independent of inlet gas temperature. The 30 wt% alkanolamine solutions containing PZ with MEA were the appropriate absorbents compared with the single alkanolamine (MEA, AMP) and the mixed alkanolamine solutions containing AMP with MEA. A higher portion of PZ in alkanolamine solutions was more favorable to CO(2) removal. Owing to less contact time in the cross-flow RPB, alkanolamines having high reaction rates with CO(2) are suggested to be used. For the mixed alkanolamine solution containing 12 wt% PZ and 18 wt% MEA, the highest gas flow rate allowed to achieve the CO(2) removal efficiency more than 90% at a liquid flow rate of 0.54 L/min was of 29 L/min. The corresponding height of a transfer unit (HTU) was found to be less than 5.0 cm, lower than that in the conventional packed bed.

  8. Activated carbon monoliths for methane storage

    NASA Astrophysics Data System (ADS)

    Chada, Nagaraju; Romanos, Jimmy; Hilton, Ramsey; Suppes, Galen; Burress, Jacob; Pfeifer, Peter

    2012-02-01

    The use of adsorbent storage media for natural gas (methane) vehicles allows for the use of non-cylindrical tanks due to the decreased pressure at which the natural gas is stored. The use of carbon powder as a storage material allows for a high mass of methane stored for mass of sample, but at the cost of the tank volume. Densified carbon monoliths, however, allow for the mass of methane for volume of tank to be optimized. In this work, different activated carbon monoliths have been produced using a polymeric binder, with various synthesis parameters. The methane storage was studied using a home-built, dosing-type instrument. A monolith with optimal parameters has been fabricated. The gravimetric excess adsorption for the optimized monolith was found to be 161 g methane for kg carbon.

  9. Activated carbon passes tests for acid-gas cleanup

    SciTech Connect

    Harruff, L.G.; Bushkuhl, S.J.

    1996-06-24

    Use of activated carbon to remove hydrocarbon contaminants from the acid-gas feed to Claus sulfur-recovery units has been successfully pilot tested in Saudi Arabia. Pilot plant results are discussed here along with issues involved in scale-up to commercial size. Heavy hydrocarbons, particularly benzene, toluene, and xylene (BTX) have been linked to coke formation and catalyst deactivation in Claus converters. This deactivation results in reduced sulfur recovery and increased sulfur emissions from these plants. This clean-up process was proven to be capable of removing 95% of the BTX and other C{sub 6}+s from acid gas over a wide range of actual plant conditions. Following the adsorption step, the activated carbon was easily regenerated by use of low-pressure steam. A post-regeneration drying step using plant fuel gas also proved beneficial. The paper discusses feed contaminants, vapor-phase cleanup, testing design, test parameters and results, bed drying after regeneration, regeneration conditions, basic flow, system control, and full-scale installation.

  10. Effect of various sources of organic carbon and high nitrite and nitrate concentrations on the selection of denitrifying bacteria. II. Continuous cultures in packed bed reactors.

    PubMed

    Błaszczyk, M

    1983-01-01

    The effect of different organic compounds, nitrites and nitrates at the concentration of 1,000 mg N/l on the quantitative and strain-specific selection of denitrifying bacteria was determined in anaerobic packed bed reactors. Both the source of carbon and nitrogen form influenced strain specificity and the frequency of occurrence of denitrifying bacteria. The frequency of denitrifying bacteria within packed bed reactor ranged in different media from 11% (glucose and nitrates) to 100% (methanol and ethanol with nitrates). A single species selection was observed in the presence of nitrites within packed bed reactor: Pseudomonas aeruginosa in medium with acetate. Pseudomonas stutzeri in medium with ethanol, Pseudomonas mendocina in medium with methanol and Pseudomonas fluorescens in medium with glucose. When nitrates were present in packed bed reactor, the dominating bacteria were: P. stutzeri in medium with acetate, P. fluorescens in medium with ethanol, Paracoccus denitrificans in medium with methanol and Alcaligenes faecalis in medium with glucose. PMID:6194668

  11. Adsorption of hydrogen sulfide onto activated carbon fibers: effect of pore structure and surface chemistry.

    PubMed

    Feng, Wenguo; Kwon, Seokjoon; Borguet, Eric; Vidic, Radisav

    2005-12-15

    To understand the nature of H2S adsorption onto carbon surfaces under dry and anoxic conditions, the effects of carbon pore structure and surface chemistry were studied using activated carbon fibers (ACFs) with different pore structures and surface areas. Surface pretreatments, including oxidation and heattreatment, were conducted before adsorption/desorption tests in a fixed-bed reactor. Raw ACFs with higher surface area showed greater adsorption and retention of sulfur, and heat treatment further enhanced adsorption and retention of sulfur. The retained amount of hydrogen sulfide correlated well with the amount of basic functional groups on the carbon surface, while the desorbed amount reflected the effect of pore structure. Temperature-programmed desorption (TPD) and thermal gravimetric analysis (TGA) showed that the retained sulfurous compounds were strongly bonded to the carbon surface. In addition, surface chemistry of the sorbent might determine the predominant form of adsorbate on the surface. PMID:16475362

  12. Adsorption of hydrogen sulfide onto activated carbon fibers: effect of pore structure and surface chemistry.

    PubMed

    Feng, Wenguo; Kwon, Seokjoon; Borguet, Eric; Vidic, Radisav

    2005-12-15

    To understand the nature of H2S adsorption onto carbon surfaces under dry and anoxic conditions, the effects of carbon pore structure and surface chemistry were studied using activated carbon fibers (ACFs) with different pore structures and surface areas. Surface pretreatments, including oxidation and heattreatment, were conducted before adsorption/desorption tests in a fixed-bed reactor. Raw ACFs with higher surface area showed greater adsorption and retention of sulfur, and heat treatment further enhanced adsorption and retention of sulfur. The retained amount of hydrogen sulfide correlated well with the amount of basic functional groups on the carbon surface, while the desorbed amount reflected the effect of pore structure. Temperature-programmed desorption (TPD) and thermal gravimetric analysis (TGA) showed that the retained sulfurous compounds were strongly bonded to the carbon surface. In addition, surface chemistry of the sorbent might determine the predominant form of adsorbate on the surface.

  13. Biocatalytic methanation of hydrogen and carbon dioxide in a fixed bed bioreactor.

    PubMed

    Alitalo, Anni; Niskanen, Marko; Aura, Erkki

    2015-11-01

    Biocatalytic methanation of H2 and CO2 was studied in a fixed bed reactor system consisting of two solid state bioreactors in series connected to a recirculation system. Bioreactors were packed with a mixture of vermiculite shales and granular perlite material as a support material. A maximal methane productivity of 6.35l/lreactord was achieved at a hydrogen feed rate of 25.2l/lreactord, while hydrogen conversion rate was 100%. However, stable operation of the reactor at this efficiency remains to be achieved. Very simple reactor design, constructed from low cost materials, and the idea of exploiting waste material as a robust source of nutrients for methanogens makes this study very interesting regarding the overall usability and suitability of the system as part of a decentralized energy system. PMID:26298404

  14. Preparation of activated carbons with mesopores by use of organometallics

    SciTech Connect

    Yamada, Yoshio; Yoshizawa, Noriko; Furuta, Takeshi

    1996-12-31

    Activated carbons are commercially produced by steam or CO{sub 2} activation of coal, coconut shell and so on. In general the carbons obtained give pores with a broad range of distribution. The objective of this study was to prepare activated carbons from coal by use of various organometallic compounds. The carbons were evaluated for pore size by nitrogen adsorption experiments.

  15. USING POWDERED ACTIVATED CARBON: A CRITICAL REVIEW

    EPA Science Inventory

    Because the performance of powdered activated carbon (PAC) for uses other than taste and odor control is poorly documented, the purpose of this article is to critically review uses that have been reported (i.e., pesticides and herbicides, synthetic organic chemicals, and trihalom...

  16. MODELING MERCURY CONTROL WITH POWDERED ACTIVATED CARBON

    EPA Science Inventory

    The paper presents a mathematical model of total mercury removed from the flue gas at coal-fired plants equipped with powdered activated carbon (PAC) injection for Mercury control. The developed algorithms account for mercury removal by both existing equipment and an added PAC in...

  17. Seasonal composition and activity of sulfate-reducing prokaryotic communities in seagrass bed sediments

    EPA Science Inventory

    Sulfate-reducing prokaryotes (SRP) play a key role in the carbon and nutrient cycles of coastal marine, vegetated ecosystems, but the interactions of SRP communities with aquatic plants remain little studied. The abundance, activity, and community composition of SRP was studied i...

  18. Effect of Amount of Carbon on the Reduction Efficiency of Iron Ore-Coal Composite Pellets in Multi-layer Bed Rotary Hearth Furnace (RHF)

    NASA Astrophysics Data System (ADS)

    Mishra, Srinibash; Roy, Gour Gopal

    2016-08-01

    The effect of carbon-to-hematite molar ratio has been studied on the reduction efficiency of iron ore-coal composite pellet reduced at 1523 K (1250 °C) for 20 minutes in a laboratory scale multi-layer bed rotary hearth furnace (RHF). Reduced pellets have been characterized through weight loss measurement, estimation of porosity, shrinkage, qualitative and quantitative phase analysis by XRD. Performance parameters such as the degree of reduction, metallization, carbon efficiency, productivity, and compressive strength have been calculated to compare the process efficacy at different carbon levels in the pellets. Pellets with optimum carbon-to-hematite ratio (C/Fe2O3 molar ratio = 1.66) that is much below the stoichiometric carbon required for direct reduction of hematite yielded maximum reduction, better carbon utilization, and productivity for all three layers. Top layer exhibited maximum reduction at comparatively lower carbon level (C/Fe2O3 molar ratio <2.33) in the pellet, while bottom layer exceeded top layer reduction at higher carbon level (C/Fe2O3 molar ratio >2.33). Correlation between degree of reduction and metallization indicated non-isothermal kinetics influenced by heat and mass transfer in multi-layer bed RHF. Compressive strength of the partially reduced pellet with optimum carbon content (C/Fe2O3 molar ratio = 1.66) showed that they could be potentially used as an alternate feed in a blast furnace or any other smelting reactor.

  19. Trace Elements Affect Methanogenic Activity and Diversity in Enrichments from Subsurface Coal Bed Produced Water

    PubMed Central

    Ünal, Burcu; Perry, Verlin Ryan; Sheth, Mili; Gomez-Alvarez, Vicente; Chin, Kuk-Jeong; Nüsslein, Klaus

    2012-01-01

    Microbial methane from coal beds accounts for a significant and growing percentage of natural gas worldwide. Our knowledge of physical and geochemical factors regulating methanogenesis is still in its infancy. We hypothesized that in these closed systems, trace elements (as micronutrients) are a limiting factor for methanogenic growth and activity. Trace elements are essential components of enzymes or cofactors of metabolic pathways associated with methanogenesis. This study examined the effects of eight trace elements (iron, nickel, cobalt, molybdenum, zinc, manganese, boron, and copper) on methane production, on mcrA transcript levels, and on methanogenic community structure in enrichment cultures obtained from coal bed methane (CBM) well produced water samples from the Powder River Basin, Wyoming. Methane production was shown to be limited both by a lack of additional trace elements as well as by the addition of an overly concentrated trace element mixture. Addition of trace elements at concentrations optimized for standard media enhanced methane production by 37%. After 7 days of incubation, the levels of mcrA transcripts in enrichment cultures with trace element amendment were much higher than in cultures without amendment. Transcript levels of mcrA correlated positively with elevated rates of methane production in supplemented enrichments (R2 = 0.95). Metabolically active methanogens, identified by clone sequences of mcrA mRNA retrieved from enrichment cultures, were closely related to Methanobacterium subterraneum and Methanobacterium formicicum. Enrichment cultures were dominated by M. subterraneum and had slightly higher predicted methanogenic richness, but less diversity than enrichment cultures without amendments. These results suggest that varying concentrations of trace elements in produced water from different subsurface coal wells may cause changing levels of CBM production and alter the composition of the active methanogenic community. PMID

  20. Geochemistry of dissolved inorganic carbon in a Coastal Plain aquifer. 1. Sulfate from confining beds as an oxidant in microbial CO2 production

    USGS Publications Warehouse

    Chapelle, F.H.; McMahon, P.B.

    1991-01-01

    A primary source of dissolved inorganic carbon (DIC) in the Black Creek aquifer of South Carolina is carbon dioxide produced by microbially mediated oxidation of sedimentary organic matter. Groundwater chemistry data indicate, however, that the available mass of inorganic electron acceptors (oxygen, Fe(III), and sulfate) and observed methane production is inadequate to account for observed CO2 production. Although sulfate concentrations are low (approximately 0.05-0.10 mM) in aquifer water throughout the flow system, sulfate concentrations are greater in confining-bed pore water (0.4-20 mM). The distribution of culturable sulfate-reducing bacteria in these sediments suggests that this concentration gradient is maintained by greater sulfate-reducing activity in sands than in clays. Calculations based on Fick's Law indicate that possible rates of sulfate diffusion to aquifer sediments are sufficient to explain observed rates of CO2 production (about 10-5 mmoll-1 year-1), thus eliminating the apparent electron-acceptor deficit. Furthermore, concentrations of dissolved hydrogen in aquifer water are in the range characteristic of sulfate reduction (2-6 nM), which provides independent evidence that sulfate reduction is the predominant terminal electron-accepting process in this system. The observed accumulation of pyrite- and calcite-cemented sandstones at sand-clay interfaces is direct physical evidence that these processes have been continuing over the history of these sediments. ?? 1991.

  1. Nitrate removal, communities of denitrifiers and adverse effects in different carbon substrates for use in denitrification beds

    PubMed Central

    Warneke, Sören; Schipper, Louis A.; Matiasek, Michael G.; Scow, Kate M.; Cameron, Stewart; Bruesewitz, Denise A.; McDonald, Ian R.

    2012-01-01

    Denitrification beds are containers filled with wood by-products that serve as a carbon and energy source to denitrifiers, which reduce nitrate ( NO3−) from point source discharges into non-reactive dinitrogen (N2) gas. This study investigates a range of alternative carbon sources and determines rates, mechanisms and factors controlling NO3− removal, denitrifying bacterial community, and the adverse effects of these substrates. Experimental barrels (0.2 m3) filled with either maize cobs, wheat straw, green waste, sawdust, pine woodchips or eucalyptus woodchips were incubated at 16.8 °C or 27.1 °C (outlet temperature), and received NO3− enriched water (14.38 mg N L−1 and 17.15 mg N L−1). After 2.5 years of incubation measurements were made of NO3−−N removal rates, in vitro denitrification rates (DR), factors limiting denitrification (carbon and nitrate availability, dissolved oxygen, temperature, pH, and concentrations of NO3−, nitrite and ammonia), copy number of nitrite reductase (nirS and nirK ) and nitrous oxide reductase (nosZ ) genes, and greenhouse gas production (dissolved nitrous oxide (N2O) and methane), and carbon (TOC) loss. Microbial denitrification was the main mechanism for NO3−−N removal. Nitrate–N removal rates ranged from 1.3 (pine woodchips) to 6.2 g N m−3 d−1 (maize cobs), and were predominantly limited by C availability and temperature (Q10 = 1.2) when NO3−−N outlet concentrations remained above 1 mg L−1. The NO3−−N removal rate did not depend directly on substrate type, but on the quantity of microbially available carbon, which differed between carbon sources. The abundance of denitrifying genes (nirS, nirK and nosZ ) was similar in replicate barrels under cold incubation, but varied substantially under warm incubation, and between substrates. Warm incubation enhanced growth of nirS containing bacteria and bacteria that lacked the nosZ gene, potentially explaining the greater N2O emission in warmer

  2. Supercapacitor Electrodes from Activated Carbon Monoliths and Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Dolah, B. N. M.; Othman, M. A. R.; Deraman, M.; Basri, N. H.; Farma, R.; Talib, I. A.; Ishak, M. M.

    2013-04-01

    Binderless monoliths of supercapacitor electrodes were prepared by the carbonization (N2) and activation (CO2) of green monoliths (GMs). GMs were made from mixtures of self-adhesive carbon grains (SACG) of fibers from oil palm empty fruit bunches and a combination of 5 & 6% KOH and 0, 5 & 6% carbon nanotubes (CNTs) by weight. The electrodes from GMs containing CNTs were found to have lower specific BET surface area (SBET). The electrochemical behavior of the supercapacitor fabricated using the prepared electrodes were investigated by electrochemical impedance spectroscopy (EIS) and galvanostatic charge-discharge (GCD). In general an addition of CNTs into the GMs reduces the equivalent series resistance (ESR) value of the cells. A cell fabricated using electrodes from GM with 5% CNT and 5% KOH was found to have the largest reduction of ESR value than that from the others GMs containing CNT. The cell has steeper Warburg's slope than that from its respective non-CNT GM, which reflect the smaller resistance for electrolyte ions to move into pores of electrodes despite these electrodes having largest reduction in specific BET surface area. The cell also has the smallest reduction of specific capacitance (Csp) and maintains the specific power range despite a reduction in the specific energy range due to the CNT addition.

  3. Monitoring endocrine activity in kraft mill effluent treated by aerobic moving bed bioreactor system.

    PubMed

    Chamorro, S; Pozo, G; Jarpa, M; Hernandez, V; Becerra, J; Vidal, G

    2010-01-01

    A Moving Bed Bioreactor (MBBR) was operated at three different hydraulic retention times for a period of 414 days. The fate of the extractive compounds and the estrogenic activity of the Pinus radiata kraft mill effluents were evaluated using Yeast Estrogen Screen (YES) and gas chromatography - mass spectrometry (GC-MS) detection. Results show that the MBBR reactor is able to remove between 80-83% of estrogenic activity present in the kraft mill Pinus radiata influent, where the values of the effluent's estrogenic activity ranged between 0.123-0.411 ng L(-1), expressed as estrogenic equivalent (EEqs) of 17-a-ethynylestradiol (EE2 eq.). Additionally, the biomass of the MBBR reactor accumulated estrogenic activity ranging between 0.29-0.37 ng EEqs EE2 during the different Hydraulic Retention Time (HRT) operations. The main groups present in pulp mills effluents, corresponding to fatty acids, hydrocarbons, phenols, sterols and triterpenes, were detected by solid phase extraction (SPE) and gas chromatography - mass spectrometry (GC-MS). The results suggest that the sterols produce the estrogenic activity in the evaluated effluent. PMID:20595766

  4. Radioactive Demonstrations Of Fluidized Bed Steam Reforming (FBSR) With Hanford Low Activity Wastes

    SciTech Connect

    Jantzen, C. M.; Crawford, C. L.; Burket, P. R.; Bannochie, C. J.; Daniel, W. G.; Nash, C. A.; Cozzi, A. D.; Herman, C. C.

    2012-10-22

    Several supplemental technologies for treating and immobilizing Hanford low activity waste (LAW) are being evaluated. One immobilization technology being considered is Fluidized Bed Steam Reforming (FBSR) which offers a low temperature (700-750?C) continuous method by which wastes high in organics, nitrates, sulfates/sulfides, or other aqueous components may be processed into a crystalline ceramic (mineral) waste form. The granular waste form produced by co-processing the waste with kaolin clay has been shown to be as durable as LAW glass. The FBSR granular product will be monolithed into a final waste form. The granular component is composed of insoluble sodium aluminosilicate (NAS) feldspathoid minerals such as sodalite. Production of the FBSR mineral product has been demonstrated both at the industrial, engineering, pilot, and laboratory scales on simulants. Radioactive testing at SRNL commenced in late 2010 to demonstrate the technology on radioactive LAW streams which is the focus of this study.

  5. An analysis of a trickle-bed bioreactor: Carbon disulfide removal

    SciTech Connect

    Lobo, R.; Revah, S.; Viveros-Garcia, T.

    1999-04-05

    An analysis of the local processes occurring in a trickle-bed bioreactor (TBB) with a first-order bioreaction shows that the identification of the TBB operating regime requires knowledge of the substrate concentration in the liquid phase. If the substrate liquid concentration is close to 0, the rate-controlling step is mass transfer at the gas-liquid interface; when it is close to the value in equilibrium with the gas phase, the controlling step is the phenomena occurring in the biofilm, CS{sub 2} removal rate data obtained in a TBB with a Thiobacilii consortia biofilm are analyzed to obtain the mass transfer and kinetic parameters, and to show that the bioreactor operates in a regime mainly controlled by mass transfer. A TBB model with two experimentally determined parameters is developed and used to show how the bioreactor size depends on the rate-limiting step, the absorption factor, the substrate fractional conversion, and on the gas and liquid contact pattern. Under certain conditions, the TBB size is independent of the flowing phases` contact pattern. The model effectively describes substrate gas and liquid concentration data for mass transfer and biodegradation rate controlled processes.

  6. An analysis of a trickle-bed bioreactor: carbon disulfide removal.

    PubMed

    Lobo, R; Revah, S; Viveros-García, T

    1999-04-01

    An analysis of the local processes occurring in a trickle-bed bioreactor (TBB) with a first-order bioreaction shows that the identification of the TBB operating regime requires knowledge of the substrate concentration in the liquid phase. If the substrate liquid concentration is close to 0, the rate-controlling step is mass transfer at the gas-liquid interface; when it is close to the value in equilibrium with the gas phase, the controlling step is the phenomena occurring in the biofilm. CS2 removal rate data obtained in a TBB with a Thiobacilii consortia biofilm are analyzed to obtain the mass transfer and kinetic parameters, and to show that the bioreactor operates in a regime mainly controlled by mass transfer. A TBB model with two experimentally determined parameters is developed and used to show how the bioreactor size depends on the rate-limiting step, the absorption factor, the substrate fractional conversion, and on the gas and liquid contact pattern. Under certain conditions, the TBB size is independent of the flowing phases' contact pattern. The model effectively describes substrate gas and liquid concentration data for mass transfer and biodegradation rate controlled processes.

  7. Modeling of moisture diffusivity, activation energy and energy consumption in fluidized bed drying of rough rice

    NASA Astrophysics Data System (ADS)

    Khanali, Majid; Banisharif, Alireza; Rafiee, Shahin

    2016-01-01

    The present work was an attempt to assess the effective moisture diffusivity, activation energy, and energy consumption of rough rice in a batch fluidized bed dryer. Drying experiments were conducted at drying air temperatures of 50, 60, and 70 °C, superficial fluidization velocities of 2.3, 2.5, and 2.8 m/s, and solids holdup of 1.32 kg. Drying kinetics showed that the whole fluidized bed drying of rough rice occurred in the falling rate period. The effective moisture diffusivity was described by an Arrhenius equation. The evaluated effective moisture diffusivity increased with drying air temperature and superficial fluidization velocity and was found to vary from 4.78 × 10-11 to 1.364 × 10-10 m2/s with R2 higher than 0.9643. The activation energy and the pre-exponential factor of Arrhenius equation were found to be in the range of 36.59-44.31 kJ/mol and 4.71 × 10-5-7.15 × 10-4 m2/s, respectively. Both maximum values of the specific energy consumption of 74.73 MJ/kg and the total energy need of 12.43 MJ were obtained at 60 °C drying air temperature and 2.8 m/s superficial fluidization velocity. Both minimum values of the specific energy consumption of 29.98 MJ/kg and the total energy need of 4.85 MJ were obtained under drying air temperature of 70 °C and superficial fluidization velocity of 2.3 m/s.

  8. Modeling of moisture diffusivity, activation energy and energy consumption in fluidized bed drying of rough rice

    NASA Astrophysics Data System (ADS)

    Khanali, Majid; Banisharif, Alireza; Rafiee, Shahin

    2016-11-01

    The present work was an attempt to assess the effective moisture diffusivity, activation energy, and energy consumption of rough rice in a batch fluidized bed dryer. Drying experiments were conducted at drying air temperatures of 50, 60, and 70 °C, superficial fluidization velocities of 2.3, 2.5, and 2.8 m/s, and solids holdup of 1.32 kg. Drying kinetics showed that the whole fluidized bed drying of rough rice occurred in the falling rate period. The effective moisture diffusivity was described by an Arrhenius equation. The evaluated effective moisture diffusivity increased with drying air temperature and superficial fluidization velocity and was found to vary from 4.78 × 10-11 to 1.364 × 10-10 m2/s with R2 higher than 0.9643. The activation energy and the pre-exponential factor of Arrhenius equation were found to be in the range of 36.59-44.31 kJ/mol and 4.71 × 10-5-7.15 × 10-4 m2/s, respectively. Both maximum values of the specific energy consumption of 74.73 MJ/kg and the total energy need of 12.43 MJ were obtained at 60 °C drying air temperature and 2.8 m/s superficial fluidization velocity. Both minimum values of the specific energy consumption of 29.98 MJ/kg and the total energy need of 4.85 MJ were obtained under drying air temperature of 70 °C and superficial fluidization velocity of 2.3 m/s.

  9. Treatment of sludge containing nitro-aromatic compounds in reed-bed mesocosms - Water, BOD, carbon and nutrient removal

    SciTech Connect

    Gustavsson, L.; Engwall, M.

    2012-01-15

    Highlights: Black-Right-Pointing-Pointer It is necessary to improve existing and develop new sludge management techniques. Black-Right-Pointing-Pointer One method is dewatering and biodegradation of compounds in constructed wetlands. Black-Right-Pointing-Pointer The result showed high reduction of all tested parameters after treatment. Black-Right-Pointing-Pointer Plants improve degradation and Phragmites australis is tolerant to xenobiotics. Black-Right-Pointing-Pointer The amount of sludge could be reduced by 50-70%. - Abstract: Since the mid-1970s, Sweden has been depositing 1 million ton d.w sludge/year, produced at waste water treatment plants. Due to recent legislation this practice is no longer a viable method of waste management. It is necessary to improve existing and develop new sludge management techniques and one promising alternative is the dewatering and treatment of sludge in constructed wetlands. The aim of this study was to follow reduction of organic carbon, BOD and nutrients in an industrial sludge containing nitro-aromatic compounds passing through constructed small-scale wetlands, and to investigate any toxic effect such as growth inhibition of the common reed Phragmites australis. The result showed high reduction of all tested parameters in all the outgoing water samples, which shows that constructed wetlands are suitable for carbon and nutrient removal. The results also showed that P. australis is tolerant to xenobiotics and did not appear to be affected by the toxic compounds in the sludge. The sludge residual on the top of the beds contained low levels of organic carbon and is considered non-organic and could therefore be landfilled. Using this type of secondary treatment method, the amount of sludge could be reduced by 50-70%, mainly by dewatering and biodegradation of organic compounds.

  10. Production of granular activated carbon from food-processing wastes (walnut shells and jujube seeds) and its adsorptive properties.

    PubMed

    Bae, Wookeun; Kim, Jongho; Chung, Jinwook

    2014-08-01

    Commercial activated carbon is a highly effective absorbent that can be used to remove micropollutants from water. As a result, the demand for activated carbon is increasing. In this study, we investigated the optimum manufacturing conditions for producing activated carbon from ligneous wastes generated from food processing. Jujube seeds and walnut shells were selected as raw materials. Carbonization and steam activation were performed in a fixed-bed laboratory electric furnace. To obtain the highest iodine number, the optimum conditions for producing activated carbon from jujube seeds and walnut shells were 2 hr and 1.5 hr (carbonization at 700 degrees C) followed by 1 hr and 0.5 hr (activation at 1000 degrees C), respectively. The surface area and iodine number of activated carbon made from jujube seeds and walnut shells were 1,477 and 1,184 m2/g and 1,450 and 1,200 mg/g, respectively. A pore-distribution analysis revealed that most pores had a pore diameter within or around 30-40 angstroms, and adsorption capacity for surfactants was about 2 times larger than the commercial activated carbon, indicating that waste-based activated carbon can be used as alternative. Implications: Wastes discharged from agricultural and food industries results in a serious environmental problem. A method is proposed to convert food-processing wastes such as jujube seeds and walnut shells into high-grade granular activated carbon. Especially, the performance of jujube seeds as activated carbon is worthy of close attention. There is little research about the application ofjujube seeds. Also, when compared to two commercial carbons (Samchully and Calgon samples), the results show that it is possible to produce high-quality carbon, particularly from jujube seed, using a one-stage, 1,000 degrees C, steam pyrolysis. The preparation of activated carbon from food-processing wastes could increase economic return and reduce pollution.

  11. Production of granular activated carbon from food-processing wastes (walnut shells and jujube seeds) and its adsorptive properties.

    PubMed

    Bae, Wookeun; Kim, Jongho; Chung, Jinwook

    2014-08-01

    Commercial activated carbon is a highly effective absorbent that can be used to remove micropollutants from water. As a result, the demand for activated carbon is increasing. In this study, we investigated the optimum manufacturing conditions for producing activated carbon from ligneous wastes generated from food processing. Jujube seeds and walnut shells were selected as raw materials. Carbonization and steam activation were performed in a fixed-bed laboratory electric furnace. To obtain the highest iodine number, the optimum conditions for producing activated carbon from jujube seeds and walnut shells were 2 hr and 1.5 hr (carbonization at 700 degrees C) followed by 1 hr and 0.5 hr (activation at 1000 degrees C), respectively. The surface area and iodine number of activated carbon made from jujube seeds and walnut shells were 1,477 and 1,184 m2/g and 1,450 and 1,200 mg/g, respectively. A pore-distribution analysis revealed that most pores had a pore diameter within or around 30-40 angstroms, and adsorption capacity for surfactants was about 2 times larger than the commercial activated carbon, indicating that waste-based activated carbon can be used as alternative. Implications: Wastes discharged from agricultural and food industries results in a serious environmental problem. A method is proposed to convert food-processing wastes such as jujube seeds and walnut shells into high-grade granular activated carbon. Especially, the performance of jujube seeds as activated carbon is worthy of close attention. There is little research about the application ofjujube seeds. Also, when compared to two commercial carbons (Samchully and Calgon samples), the results show that it is possible to produce high-quality carbon, particularly from jujube seed, using a one-stage, 1,000 degrees C, steam pyrolysis. The preparation of activated carbon from food-processing wastes could increase economic return and reduce pollution. PMID:25185390

  12. Carbon nanomaterials: Biologically active fullerene derivatives.

    PubMed

    Bogdanović, Gordana; Djordjević, Aleksandar

    2016-01-01

    Since their discovery, fullerenes, carbon nanotubes, and graphene attract significant attention of researches in various scientific fields including biomedicine. Nano-scale size and a possibility for diverse surface modifications allow carbon nanoallotropes to become an indispensable nanostructured material in nanotechnologies, including nanomedicine. Manipulation of surface chemistry has created diverse populations of water-soluble derivatives of fullerenes, which exhibit different behaviors. Both non-derivatized and derivatized fullerenes show various biological activities. Cellular processes that underline their toxicity are oxidative, genotoxic, and cytotoxic responses.The antioxidant/cytoprotective properties of fullerenes and derivatives have been considered in the prevention of organ oxidative damage and treatment. The same unique physiochemical properties of nanomaterials may also be associated with potential health hazards. Non-biodegradability and toxicity of carbon nanoparticles still remain a great concern in the area of biomedical application. In this review, we report on basic physical and chemical properties of carbon nano-clusters--fullerenes, nanotubes, and grapheme--their specificities, activities, and potential application in biological systems. Special emphasis is given to our most important results obtained in vitro and in vivo using polyhydroxylated fullerene derivative C₆₀(OH)₂₄.

  13. Carbon nanomaterials: Biologically active fullerene derivatives.

    PubMed

    Bogdanović, Gordana; Djordjević, Aleksandar

    2016-01-01

    Since their discovery, fullerenes, carbon nanotubes, and graphene attract significant attention of researches in various scientific fields including biomedicine. Nano-scale size and a possibility for diverse surface modifications allow carbon nanoallotropes to become an indispensable nanostructured material in nanotechnologies, including nanomedicine. Manipulation of surface chemistry has created diverse populations of water-soluble derivatives of fullerenes, which exhibit different behaviors. Both non-derivatized and derivatized fullerenes show various biological activities. Cellular processes that underline their toxicity are oxidative, genotoxic, and cytotoxic responses.The antioxidant/cytoprotective properties of fullerenes and derivatives have been considered in the prevention of organ oxidative damage and treatment. The same unique physiochemical properties of nanomaterials may also be associated with potential health hazards. Non-biodegradability and toxicity of carbon nanoparticles still remain a great concern in the area of biomedical application. In this review, we report on basic physical and chemical properties of carbon nano-clusters--fullerenes, nanotubes, and grapheme--their specificities, activities, and potential application in biological systems. Special emphasis is given to our most important results obtained in vitro and in vivo using polyhydroxylated fullerene derivative C₆₀(OH)₂₄. PMID:27483572

  14. Enhanced capacitive properties of commercial activated carbon by re-activation in molten carbonates

    NASA Astrophysics Data System (ADS)

    Lu, Beihu; Xiao, Zuoan; Zhu, Hua; Xiao, Wei; Wu, Wenlong; Wang, Dihua

    2015-12-01

    Simple, affordable and green methods to improve capacitive properties of commercial activated carbon (AC) are intriguing since ACs possess a predominant role in the commercial supercapacitor market. Herein, we report a green reactivation of commercial ACs by soaking ACs in molten Na2CO3-K2CO3 (equal in mass ratios) at 850 °C combining the merits of both physical and chemical activation strategies. The mechanism of molten carbonate treatment and structure-capacitive activity correlations of the ACs are rationalized. Characterizations show that the molten carbonate treatment increases the electrical conductivity of AC without compromising its porosity and wettability of electrolytes. Electrochemical tests show the treated AC exhibited higher specific capacitance, enhanced high-rate capability and excellent cycle performance, promising its practical application in supercapacitors. The present study confirms that the molten carbonate reactivation is a green and effective method to enhance capacitive properties of ACs.

  15. Kinetics of adsorption with granular, powdered, and fibrous activated carbon

    SciTech Connect

    Shmidt, J.L.; Pimenov, A.V.; Lieberman, A.I.; Cheh, H.Y.

    1997-08-01

    The properties of three different types of activated carbon, fibrous, powdered, and granular, were investigated theoretically and experimentally. The adsorption rate of the activated carbon fiber was found to be two orders of magnitude higher than that of the granular activated carbon, and one order of magnitude higher than that of the powdered activated carbon. Diffusion coefficients of methylene blue in the fibrous, powdered, and granular activated carbons were determined experimentally. A new method for estimating the meso- and macropore surface areas in these carbons was proposed.

  16. Multiphase flow simulations of a moving fluidized bed regenerator in a carbon capture unit

    SciTech Connect

    Sarkar, Avik; Pan, Wenxiao; Suh, Dong-Myung; Huckaby, E. D.; Sun, Xin

    2014-10-01

    To accelerate the commercialization and deployment of carbon capture technologies, computational fluid dynamics (CFD)-based tools may be used to model and analyze the performance of carbon capture devices. This work presents multiphase CFD-based flow simulations for the regeneration device responsible for extracting CO2 from CO2-loaded sorbent particles before the particles are recycled. The use of solid particle sorbents in this design is a departure from previously reported systems, where aqueous sorbents are employed. Another new feature is the inclusion of a series of perforated plates along the regenerator height. The influence of these plates on sorbent distribution is examined for varying sorbent holdup, fluidizing gas velocity, and particle size. The residence time distribution of sorbents is also measured to classify the low regime as plug flow or well-mixed flow. The purpose of this work is to better understand the sorbent flow characteristics before reaction kinetics of CO2 desorption can be implemented.

  17. Aqueous mercury adsorption by activated carbons.

    PubMed

    Hadi, Pejman; To, Ming-Ho; Hui, Chi-Wai; Lin, Carol Sze Ki; McKay, Gordon

    2015-04-15

    Due to serious public health threats resulting from mercury pollution and its rapid distribution in our food chain through the contamination of water bodies, stringent regulations have been enacted on mercury-laden wastewater discharge. Activated carbons have been widely used in the removal of mercuric ions from aqueous effluents. The surface and textural characteristics of activated carbons are the two decisive factors in their efficiency in mercury removal from wastewater. Herein, the structural properties and binding affinity of mercuric ions from effluents have been presented. Also, specific attention has been directed to the effect of sulfur-containing functional moieties on enhancing the mercury adsorption. It has been demonstrated that surface area, pore size, pore size distribution and surface functional groups should collectively be taken into consideration in designing the optimal mercury removal process. Moreover, the mercury adsorption mechanism has been addressed using equilibrium adsorption isotherm, thermodynamic and kinetic studies. Further recommendations have been proposed with the aim of increasing the mercury removal efficiency using carbon activation processes with lower energy input, while achieving similar or even higher efficiencies.

  18. Enhanced biological denitrification in the cyclic rotating bed reactor with catechol as carbon source.

    PubMed

    Moussavi, Gholamreza; Jafari, Seyed Javad; Yaghmaeian, Kamyar

    2015-08-01

    The performance of CRBR in denitrification with catechol carbon source is presented. The influence of inlet nitrate concentration, hydraulic retention time (HRT), media filling ratio and rotational speed of media on the performance of CRBR was investigated. The bioreactor could denitrify over 95% of the nitrate at an inlet concentration up to 1000 mg NO3(-)/L and a short HRT as low as 18 h. The optimum media filling ratio at which the maximum denitrification was achieved in the CRBR was 30% and the contribution of media at this condition was around 36%. The optimum ratio of media filling at which the maximum denitrification was 20 rpm and the contribution of rotational speed under this condition was around 17%. According to the findings, the CRBR is a high rate bioreactor and thus serves as an appropriate technology for denitrification of wastewaters containing a high concentration of nitrate and toxic organic compounds. PMID:25898088

  19. Determination of pressure drop across activated carbon fiber respirator cartridges.

    PubMed

    Balanay, Jo Anne G; Lungu, Claudiu T

    2016-01-01

    Activated carbon fiber (ACF) is considered as an alternative adsorbent to granular activated carbon (GAC) for the development of thinner, lighter, and efficient respirators because of their larger surface area and adsorption capacities, thinner critical bed depth, lighter weight, and fabric form. This study aims to measure the pressure drop across different types of commercially available ACFs in respirator cartridges to determine the ACF composition and density that will result in acceptably breathable respirators. Seven ACF types in cloth (ACFC) and felt (ACFF) forms were tested. ACFs in cartridges were challenged with pre-conditioned constant air flow (43 LPM, 23°C, 50% RH) at different compositions (single- or combination-ACF type) in a test chamber. Pressure drop across ACF cartridges were obtained using a micromanometer, and compared among different cartridge configurations, to those of the GAC cartridge, and to the NIOSH breathing resistance requirements for respirator cartridges. Single-ACF type cartridges filled with any ACFF had pressure drop measurements (23.71-39.93 mmH2O) within the NIOSH inhalation resistance requirement of 40 mmH2O, while those of the ACFC cartridges (85.47±3.67 mmH2O) exceeded twice the limit due possibly to the denser weaving of ACFC fibers. All single ACFF-type cartridges had higher pressure drop compared to the GAC cartridge (23.13±1.14 mmH2O). Certain ACF combinations (2 ACFF or ACFC/ACFF types) resulted to pressure drop (26.39-32.81 mmH2O) below the NIOSH limit. All single-ACFF type and all combination-ACF type cartridges with acceptable pressure drop had much lower adsorbent weights than GAC (≤15.2% of GAC weight), showing potential for light-weight respirator cartridges. 100% ACFC in cartridges may result to respirators with high breathing resistance and, thus, is not recommended. The more dense ACFF and ACFC types may still be possibly used in respirators by combining them with less dense ACFF materials and/or by

  20. Determination of pressure drop across activated carbon fiber respirator cartridges.

    PubMed

    Balanay, Jo Anne G; Lungu, Claudiu T

    2016-01-01

    Activated carbon fiber (ACF) is considered as an alternative adsorbent to granular activated carbon (GAC) for the development of thinner, lighter, and efficient respirators because of their larger surface area and adsorption capacities, thinner critical bed depth, lighter weight, and fabric form. This study aims to measure the pressure drop across different types of commercially available ACFs in respirator cartridges to determine the ACF composition and density that will result in acceptably breathable respirators. Seven ACF types in cloth (ACFC) and felt (ACFF) forms were tested. ACFs in cartridges were challenged with pre-conditioned constant air flow (43 LPM, 23°C, 50% RH) at different compositions (single- or combination-ACF type) in a test chamber. Pressure drop across ACF cartridges were obtained using a micromanometer, and compared among different cartridge configurations, to those of the GAC cartridge, and to the NIOSH breathing resistance requirements for respirator cartridges. Single-ACF type cartridges filled with any ACFF had pressure drop measurements (23.71-39.93 mmH2O) within the NIOSH inhalation resistance requirement of 40 mmH2O, while those of the ACFC cartridges (85.47±3.67 mmH2O) exceeded twice the limit due possibly to the denser weaving of ACFC fibers. All single ACFF-type cartridges had higher pressure drop compared to the GAC cartridge (23.13±1.14 mmH2O). Certain ACF combinations (2 ACFF or ACFC/ACFF types) resulted to pressure drop (26.39-32.81 mmH2O) below the NIOSH limit. All single-ACFF type and all combination-ACF type cartridges with acceptable pressure drop had much lower adsorbent weights than GAC (≤15.2% of GAC weight), showing potential for light-weight respirator cartridges. 100% ACFC in cartridges may result to respirators with high breathing resistance and, thus, is not recommended. The more dense ACFF and ACFC types may still be possibly used in respirators by combining them with less dense ACFF materials and/or by

  1. Fluidized bed steam reformed mineral waste form performance testing to support Hanford Supplemental Low Activity Waste Immobilization Technology Selection

    SciTech Connect

    Jantzen, C. M.; Pierce, E. M.; Bannochie, C. J.; Burket, P. R.; Cozzi, A. D.; Crawford, C. L.; Daniel, W. E.; Fox, K. M.; Herman, C. C.; Miller, D. H.; Missimer, D. M.; Nash, C. A.; Williams, M. F.; Brown, C. F.; Qafoku, N. P.; Neeway, J. J.; Valenta, M. M.; Gill, G. A.; Swanberg, D. J.; Robbins, R. A.; Thompson, L. E.

    2015-10-01

    This report describes the benchscale testing with simulant and radioactive Hanford Tank Blends, mineral product characterization and testing, and monolith testing and characterization. These projects were funded by DOE EM-31 Technology Development & Deployment (TDD) Program Technical Task Plan WP-5.2.1-2010-001 and are entitled “Fluidized Bed Steam Reformer Low-Level Waste Form Qualification”, Inter-Entity Work Order (IEWO) M0SRV00054 with Washington River Protection Solutions (WRPS) entitled “Fluidized Bed Steam Reforming Treatability Studies Using Savannah River Site (SRS) Low Activity Waste and Hanford Low Activity Waste Tank Samples”, and IEWO M0SRV00080, “Fluidized Bed Steam Reforming Waste Form Qualification Testing Using SRS Low Activity Waste and Hanford Low Activity Waste Tank Samples”. This was a multi-organizational program that included Savannah River National Laboratory (SRNL), THOR® Treatment Technologies (TTT), Pacific Northwest National Laboratory (PNNL), Oak Ridge National Laboratory (ORNL), Office of River Protection (ORP), and Washington River Protection Solutions (WRPS). The SRNL testing of the non-radioactive pilot-scale Fluidized Bed Steam Reformer (FBSR) products made by TTT, subsequent SRNL monolith formulation and testing and studies of these products, and SRNL Waste Treatment Plant Secondary Waste (WTP-SW) radioactive campaign were funded by DOE Advanced Remediation Technologies (ART) Phase 2 Project in connection with a Work-For-Others (WFO) between SRNL and TTT.

  2. Agriculture--Agricultural Production 1, Seed Bed. Kit No. 6. Instructor's Manual [and] Student Learning Activity Guide.

    ERIC Educational Resources Information Center

    Sloan, Lee

    An instructor's manual and student activity guide on the seed bed are provided in this set of prevocational education materials which focuses on the vocational area of agriculture. (This set of materials is one of ninety-two prevocational education sets arranged around a cluster of seven vocational offerings: agriculture, home economics,…

  3. [Relation between neural structures possessing acetylcholinesterase activity and the hemomicrocirculatory bed of the fascia of the rat].

    PubMed

    Vshivtseva, V V; Lesova, L D

    1986-05-01

    By means of Karnovsky--Roots method the nervous apparatus of the hemomicrocirculatory bed has been revealed in the subcutaneous muscle fascia possessing acetylcholinesterase (AChE) activity. Innervational peculiarities in some microvascular branches, bushy pattern of AChE-positive nervous structures have been stated, as well as their uneven distribution along the vessels.

  4. Increased Brain Activation for Dual Tasking with 70-Days Head-Down Bed Rest

    PubMed Central

    Yuan, Peng; Koppelmans, Vincent; Reuter-Lorenz, Patricia A.; De Dios, Yiri E.; Gadd, Nichole E.; Wood, Scott J.; Riascos, Roy; Kofman, Igor S.; Bloomberg, Jacob J.; Mulavara, Ajitkumar P.; Seidler, Rachael D.

    2016-01-01

    Head-down tilt bed rest (HDBR) has been used as a spaceflight analog to simulate the effects of microgravity exposure on human physiology, sensorimotor function, and cognition on Earth. Previous studies have reported that concurrent performance of motor and cognitive tasks can be impaired during space missions. Understanding the consequences of HDBR for neural control of dual tasking may possibly provide insight into neural efficiency during spaceflight. In the current study, we evaluated how dual task performance and the underlying brain activation changed as a function of HDBR. Eighteen healthy men participated in this study. They remained continuously in the 6° head-down tilt position for 70 days. Functional MRI for bimanual finger tapping was acquired during both single task and dual task conditions, and repeated at 7 time points pre-, during- and post-HDBR. Another 12 healthy males participated as controls who did not undergo HDBR. A widely distributed network involving the frontal, parietal, cingulate, temporal, and occipital cortices exhibited increased activation for dual tasking and increased activation differences between dual and single task conditions during HDBR relative to pre- or post-HDBR. This HDBR-related brain activation increase for dual tasking implies that more neurocognitive control is needed for dual task execution during HDBR compared to pre- and post-HDBR. We observed a positive correlation between pre-to-post HDBR changes in dual-task cost of reaction time and pre-to-post HDBR change in dual-task cost of brain activation in several cerebral and cerebellar regions. These findings could be predictive of changes in dual task processing during spaceflight.

  5. Increased Brain Activation for Dual Tasking with 70-Days Head-Down Bed Rest.

    PubMed

    Yuan, Peng; Koppelmans, Vincent; Reuter-Lorenz, Patricia A; De Dios, Yiri E; Gadd, Nichole E; Wood, Scott J; Riascos, Roy; Kofman, Igor S; Bloomberg, Jacob J; Mulavara, Ajitkumar P; Seidler, Rachael D

    2016-01-01

    Head-down tilt bed rest (HDBR) has been used as a spaceflight analog to simulate the effects of microgravity exposure on human physiology, sensorimotor function, and cognition on Earth. Previous studies have reported that concurrent performance of motor and cognitive tasks can be impaired during space missions. Understanding the consequences of HDBR for neural control of dual tasking may possibly provide insight into neural efficiency during spaceflight. In the current study, we evaluated how dual task performance and the underlying brain activation changed as a function of HDBR. Eighteen healthy men participated in this study. They remained continuously in the 6° head-down tilt position for 70 days. Functional MRI for bimanual finger tapping was acquired during both single task and dual task conditions, and repeated at 7 time points pre-, during- and post-HDBR. Another 12 healthy males participated as controls who did not undergo HDBR. A widely distributed network involving the frontal, parietal, cingulate, temporal, and occipital cortices exhibited increased activation for dual tasking and increased activation differences between dual and single task conditions during HDBR relative to pre- or post-HDBR. This HDBR-related brain activation increase for dual tasking implies that more neurocognitive control is needed for dual task execution during HDBR compared to pre- and post-HDBR. We observed a positive correlation between pre-to-post HDBR changes in dual-task cost of reaction time and pre-to-post HDBR change in dual-task cost of brain activation in several cerebral and cerebellar regions. These findings could be predictive of changes in dual task processing during spaceflight. PMID:27601982

  6. Increased Brain Activation for Dual Tasking with 70-Days Head-Down Bed Rest

    PubMed Central

    Yuan, Peng; Koppelmans, Vincent; Reuter-Lorenz, Patricia A.; De Dios, Yiri E.; Gadd, Nichole E.; Wood, Scott J.; Riascos, Roy; Kofman, Igor S.; Bloomberg, Jacob J.; Mulavara, Ajitkumar P.; Seidler, Rachael D.

    2016-01-01

    Head-down tilt bed rest (HDBR) has been used as a spaceflight analog to simulate the effects of microgravity exposure on human physiology, sensorimotor function, and cognition on Earth. Previous studies have reported that concurrent performance of motor and cognitive tasks can be impaired during space missions. Understanding the consequences of HDBR for neural control of dual tasking may possibly provide insight into neural efficiency during spaceflight. In the current study, we evaluated how dual task performance and the underlying brain activation changed as a function of HDBR. Eighteen healthy men participated in this study. They remained continuously in the 6° head-down tilt position for 70 days. Functional MRI for bimanual finger tapping was acquired during both single task and dual task conditions, and repeated at 7 time points pre-, during- and post-HDBR. Another 12 healthy males participated as controls who did not undergo HDBR. A widely distributed network involving the frontal, parietal, cingulate, temporal, and occipital cortices exhibited increased activation for dual tasking and increased activation differences between dual and single task conditions during HDBR relative to pre- or post-HDBR. This HDBR-related brain activation increase for dual tasking implies that more neurocognitive control is needed for dual task execution during HDBR compared to pre- and post-HDBR. We observed a positive correlation between pre-to-post HDBR changes in dual-task cost of reaction time and pre-to-post HDBR change in dual-task cost of brain activation in several cerebral and cerebellar regions. These findings could be predictive of changes in dual task processing during spaceflight. PMID:27601982

  7. Sublethal Effects of ActiveGuard Exposure on Feeding Behavior and Fecundity of the Bed Bug (Hemiptera: Cimicidae).

    PubMed

    Jones, Susan C; Bryant, Joshua L; Sivakoff, Frances S

    2015-05-01

    Sublethal exposure to pesticides can alter insect behavior with potential for population-level consequences. We investigated sublethal effects of ActiveGuard, a permethrin-impregnated fabric, on feeding behavior and fecundity of bed bugs (Cimex lectularius L.) from five populations that ranged from susceptible to highly pyrethroid resistant. After exposure to ActiveGuard fabric or untreated fabric for 1 or 10 min, adult virgin female bed bugs were individually observed when offered a blood meal to determine feeding attempts and weight gain. Because bed bug feeding behavior is tightly coupled with its fecundity, all females were then mated, and the number of eggs laid and egg hatch rate were used as fecundity measures. We observed that pyrethroid-resistant and -susceptible bugs were not significantly different for all feeding and fecundity parameters. Bed bugs exposed to ActiveGuard for 10 min were significantly less likely to attempt to feed or successfully feed, and their average blood meal size was significantly smaller compared with individuals in all other groups. Independent of whether or not feeding occurred, females exposed to ActiveGuard for 10 min were significantly more likely to lay no eggs. Only a single female exposed to ActiveGuard for 10 min laid any eggs. Among the other fabric treatment-exposure time groups, there were no observable differences in egg numbers or hatch rates. Brief exposure of 10 min to ActiveGuard fabric appeared to decrease feeding and fecundity of pyrethroid-resistant and susceptible bed bugs, suggesting the potentially important role of sublethal exposure for the control of this ectoparasitic insect. PMID:26334815

  8. 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.

  9. Hierarchically structured activated carbon for ultracapacitors

    PubMed Central

    Kim, Mok-Hwa; Kim, Kwang-Bum; Park, Sun-Min; Roh, Kwang Chul

    2016-01-01

    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. PMID:26878820

  10. Analysis of up-flow aerated biological activated carbon filter technology in drinking water treatment.

    PubMed

    Lu, Shaoming; Liu, Jincui; Li, Shaowen; Biney, Elizabeth

    2013-01-01

    Problems have been found in the traditional post-positioned down-flow biological activated carbon filter (DBACF), such as microorganism leakage and low biodegradability. A pilot test was carried out to place a BACF between the sediment tank and the sand filter; a new technology of dual media up-flow aerated biological activated carbon filter (UBACF) was developed. Results showed that in terms of the new process, the up-flow mode was better than the down-flow. Compared with the DBACF, the problem of microorganism leakage could be well resolved with the UBACF process by adding disinfectant before the sand filtration, and a similar adsorption effect could be obtained. For the tested raw water, the COD(Mn) and NH3-N removal rate was 54.6% and 85.0%, respectively, similar to the waterworks with the DBACF process. The UBACF greatly enhanced oxygen supply capability and mass transfer rate via aeration, and the NH3-N removal ability was significantly improved from 1.5 mg/L to more than 3 mg/L. Influent to the UBACF with higher turbidity could be coped with through the primary filtration of the ceramisite layer combined with fluid-bed technology, which gave the carbon bed a low-turbidity environment of less than 1.0 NTU. The backwashing parameters and carbon abrasion rate of the two processes were almost the same.

  11. Numerical investigation of the seismic detectability of carbonate thin beds in the Boom Clay formation

    NASA Astrophysics Data System (ADS)

    Carcione, José M.; Gei, Davide

    2016-07-01

    The present study evaluates the capacity of the Boom Clay as a host rock for disposal purposes, more precisely its seismic characterization, which may assess its long-term performance to store radioactive wastes. Although the formation is relatively uniform and homogeneous, there are embedded thin layers of septaria (carbonates) that may affect the integrity of the Boom Clay. Therefore, it is essential to locate these geobodies. The seismic data to characterize the Boom Clay has been acquired at the Kruibeke test site. The inversion, which allowed us to obtain the anisotropy parameters and seismic velocities of the clay, is complemented with further information such as log and laboratory data. The attenuation properties have been estimated from equivalent formations (having similar composition and seismic velocities). The inversion yields quite consistent results although the symmetry of the medium is unusual but physically possible, since the anisotropy parameter ɛ is negative. According to a time-domain calculation of the energy velocity at four frequency bands up to 900 Hz, velocity increases with frequency, a behaviour described by the Zener model. Then, we use this model to describe anisotropy and anelasticity that are implemented into the equation of motion to compute synthetic seismograms in the space-time domain. The technique is based on memory variables and the Fourier pseudospectral method. We have computed reflection coefficients of the septaria thin layer. At normal incidence, the P-wave coefficient vanishes at specific thicknesses of the layer and there is no conversion to the S wave. For example, calculations at 600 Hz show that for thicknesses of 1 m the septarium can be detected more easily since the amplitudes are higher (nearly 0.8). Converted PS waves have a high amplitude at large offsets (between 30° and 80°) and can be useful to identify the target on this basis. Moreover, we have investigated the effect of septaria embedded in the Boom

  12. Development of a Cl-impregnated activated carbon for entrained-flow capture of elemental mercury.

    PubMed

    Ghorishi, S Behrooz; Keeney, Robert M; Serre, Shannon D; Gullett, Brian K; Jozewicz, Wojciech S

    2002-10-15

    Efforts to discern the role of an activated carbon's surface functional groups on the adsorption of elemental mercury (Hg0) and mercuric chloride demonstrated that chlorine (Cl) impregnation of a virgin activated carbon using dilute solutions of hydrogen chloride leads to increases (by a factor of 2-3) in fixed-bed capture of these mercury species. A commercially available activated carbon (DARCO FGD, NORITAmericas Inc. [FGD])was Cl-impregnated (Cl-FGD) [5 lb (2.3 kg) per batch] and tested for entrained-flow, short-time-scale capture of Hg0. In an entrained flow reactor, the Cl-FGD was introduced in Hg0-laden flue gases (86 ppb of Hg0) of varied compositions with gas/solid contact times of about 3-4 s, resulting in significant Hg0 removal (80-90%), compared to virgin FGD (10-15%). These levels of Hg0 removal were observed across a wide range of very low carbon-to-mercury weight ratios (1000-5000). Variation of the natural gas combustion flue gas composition, by doping with nitrogen oxides and sulfur dioxide, and the flow reactor temperature (100-200 degrees C) had minimal effects on Hg0 removal bythe Cl-FGD in these carbon-to-mercury weight ratios. These results demonstrate significant enhancement of activated carbon reactivity with minimal treatment and are applicable to combustion facilities equipped with downstream particulate matter removal such as an electrostatic precipitator.

  13. INVESTIGATION OF FLY ASH AND ACTIVATED CARBON OBTAINED FROM PULVERIZED COAL BOILERS

    SciTech Connect

    Edward K. Levy; Christopher Kiely

    2005-11-01

    One of the techniques for Hg capture in coal-fired boilers involves injection of activated carbon (AC) into the boiler downstream of the air preheater. Hg is adsorbed onto the AC particles and fly ash, which are then both removed in an electrostatic precipitator or baghouse. This project addresses the issues of Hg on activated carbon and on fly ash from a materials re-use point of view. It also addresses the possible connection between SCR reactors, fly ash properties and Hg capture. The project is determining the feasibility of separating AC from fly ash in a fluidized bed and of regenerating the separated AC by heating the AC to elevated temperatures in a fluidized bed. The temperatures needed to drive off the Hg from the ash in a fluidized bed are also being determined. Finally, samples of fly ash from power plants with SCR reactors for NO{sub x} control, are being analyzed to determine the effect of SCR on the ash.

  14. Investigation of Fly Ash and Activated Carbon Obtained from Pulverized Coal Boilers

    SciTech Connect

    Edward K. Levy; Christopher Kiely; Zheng Yao

    2006-08-31

    One of the techniques for Hg capture in coal-fired boilers involves injection of activated carbon (AC) into the boiler downstream of the air preheater. Hg is adsorbed onto the AC particles and fly ash, which are then both removed in an electrostatic precipitator or baghouse. This project addressed the issues of Hg on activated carbon and on fly ash from a materials re-use point of view. It also addressed the possible connection between SCR reactors, fly ash properties and Hg capture. The project has determined the feasibility of separating AC from fly ash in a fluidized bed and of regenerating the separated AC by heating the AC to elevated temperatures in a fluidized bed. The temperatures needed to drive off the Hg from the ash in a fluidized bed have also been determined. Finally, samples of fly ash from power plants with SCR reactors for NO{sub x} control have been analyzed in an effort to determine the effects of SCR on the ash.

  15. INVESTIGATION OF FLY ASH AND ACTIVATED CARBON OBTAINED FROM PULVERIZED COAL BOILERS

    SciTech Connect

    Edward K. Levy; Christopher Kiely

    2004-11-01

    One of the techniques for Hg capture in coal-fired boilers involves injection of activated carbon (AC) into the boiler downstream of the air preheater. Hg is adsorbed onto the AC particles and fly ash, which are then both removed in an electrostatic precipitator or baghouse. This project addresses the issues of Hg on activated carbon and on fly ash from a materials re-use point of view. It also addresses the possible connection between SCR reactors, fly ash properties and Hg capture. The project is determining the feasibility of separating AC from fly ash in a fluidized bed and of regenerating the separated AC by heating the AC to elevated temperatures in a fluidized bed. The temperatures needed to drive off the Hg from the ash in a fluidized bed are also being determined. Finally, samples of fly ash from power plants with SCR reactors for NO{sub x} control, are being analyzed to determine the effect of SCR on the ash. These analyses will also determine the properties of ash which are important for Hg capture.

  16. Second generation pressurized fluidized-bed combustion (PFBC) research and development, Phase 2 --- Task 4, carbonizer testing. Volume 2, Data reconciliation

    SciTech Connect

    Froehlich, R.; Robertson, A.; Vanhook, J.; Goyal, A.; Rehmat, A.; Newby, R.

    1994-11-01

    During the period beginning November 1991 and ending September 1992, a series of tests were conducted at Foster Wheeler Development Corporation in a fluidized-bed coal carbonizer to determine its performance characteristics. The carbonizer was operated for 533 hours in a jetting fluidized-bed configuration during which 36 set points (steady-state periods) were achieved. Extensive data were collected on the feed and product stream compositions, heating values, temperatures, and flow rates. With these data, elemental and energy balances were computed to evaluate and confirm accuracy of the data. The carbonizer data were not as self-consistent as could be desired (balance closure imperfection). A software package developed by Science Ventures, Inc., of California, called BALAID, was used to reconcile the carbonizer data; the details of the reconciliation have been given in Volume 1 of this report. The reconciled data for the carbonizer were rigorously analyzed, correlations were developed, and the model was updated accordingly. The model was then used in simulating each of the 36 steady-state periods achieved in the pilot plant. The details are given in this Volume one. This Volume 2 provides details of the carbonizer data reconciliation.

  17. Vibration damping with active carbon fiber structures

    NASA Astrophysics Data System (ADS)

    Neugebauer, Reimund; Kunze, Holger; Riedel, Mathias; Roscher, Hans-Jürgen

    2007-04-01

    This paper presents a mechatronic strategy for active reduction of vibrations on machine tool struts or car shafts. The active structure is built from a carbon fiber composite with embedded piezofiber actuators that are composed of piezopatches based on the Macro Fiber Composite (MFC) technology, licensed by NASA and produced by Smart Material GmbH in Dresden, Germany. The structure of these actuators allows separate or selectively combined bending and torsion, meaning that both bending and torsion vibrations can be actively absorbed. Initial simulation work was done with a finite element model (ANSYS). This paper describes how state space models are generated out of a structure based on the finite element model and how controller codes are integrated into finite element models for transient analysis and the model-based control design. Finally, it showcases initial experimental findings and provides an outlook for damping multi-mode resonances with a parallel combination of resonant controllers.

  18. Design method for adsorption beds

    NASA Technical Reports Server (NTRS)

    Blakely, R. L.; Jackson, J. K.

    1970-01-01

    Regenerable adsorption beds for long-term life support systems include synthetic geolite to remove carbon dioxide and silica gel to dehumidify the atmospheric gas prior to its passage through the geolite beds. Bed performance is evaluated from adsorption characteristics, heat and mass transfer, and pressure drop.

  19. Fluidized bed combustor modeling

    NASA Technical Reports Server (NTRS)

    Horio, M.; Rengarajan, P.; Krishnan, R.; Wen, C. Y.

    1977-01-01

    A general mathematical model for the prediction of performance of a fluidized bed coal combustor (FBC) is developed. The basic elements of the model consist of: (1) hydrodynamics of gas and solids in the combustor; (2) description of gas and solids contacting pattern; (3) kinetics of combustion; and (4) absorption of SO2 by limestone in the bed. The model is capable of calculating the combustion efficiency, axial bed temperature profile, carbon hold-up in the bed, oxygen and SO2 concentrations in the bubble and emulsion phases, sulfur retention efficiency and particulate carry over by elutriation. The effects of bed geometry, excess air, location of heat transfer coils in the bed, calcium to sulfur ratio in the feeds, etc. are examined. The calculated results are compared with experimental data. Agreement between the calculated results and the observed data are satisfactory in most cases. Recommendations to enhance the accuracy of prediction of the model are suggested.

  20. Charcoal and activated carbon at elevated pressure

    SciTech Connect

    Antal, M.J. Jr.; Dai, Xiangfeng; Norberg, N.

    1995-12-01

    High quality charcoal has been produced with very high yields of 50% to 60% from macadamia nut and kukui nut shells and of 44% to 47% from Eucalyptus and Leucaena wood in a bench scale unit at elevated pressure on a 2 to 3 hour cycle, compared to commercial practice of 25% to 30% yield on a 7 to 12 day operating cycle. Neither air pollution nor tar is produced by the process. The effects of feedstock pretreatments with metal additives on charcoal yield are evaluated in this paper. Also, the influences of steam and air partial pressure and total pressure on yields of activated carbon from high yield charcoal are presented.

  1. Adsorbed natural gas storage with activated carbon

    SciTech Connect

    Sun, Jian; Brady, T.A.; Rood, M.J.

    1996-12-31

    Despite technical advances to reduce air pollution emissions, motor vehicles still account for 30 to 70% emissions of all urban air pollutants. The Clean Air Act Amendments of 1990 require 100 cities in the United States to reduce the amount of their smog within 5 to 15 years. Hence, auto emissions, the major cause of smog, must be reduced 30 to 60% by 1998. Natural gas con be combusted with less pollutant emissions. Adsorbed natural gas (ANG) uses adsorbents and operates with a low storage pressure which results in lower capital costs and maintenance. This paper describes the production of an activated carbon adsorbent produced from an Illinois coal for ANG.

  2. MBBR system performance improvement for petroleum hydrocarbon removal using modified media with activated carbon.

    PubMed

    Sayyahzadeh, Amir Hossein; Ganjidoust, Hossein; Ayati, Bita

    2016-01-01

    Moving bed biofilm reactor (MBBR) system has a successful operation in the treatment of different types of wastewater. Since the media, i.e. the place of growth and formation of biofilm, play the main role in the treatment in this system, MBBR systems were operated in the present research with modified Bee-cell media. Activated carbon granules of almond or walnut shells were placed in media pores to improve the treatment of refinery oil wastewater and their operation with MBBR system was compared with the conventional Bee-cell media. In these experiments, the effects of organic loading rate, hydraulic retention time (HRT), media filling ratio (MFR), and activated carbon concentration (ACC) used in the media were investigated on the operation of MBBR systems. The analysis of results estimated the optimal values of HRT, MFR, and ACC used in the media between the studied levels, being equal to 22 h, 50%, and 7.5 g/L, respectively. Under these conditions, total petroleum hydrocarbons removal efficiencies for MBBR systems using Bee-cell media with carbon of almond, carbon of walnut shells, and a carbon-free system were 95 ± 1.17%, 91 ± 1.11%, and 57 ± 1.7%, respectively, which confirms the adsorption ability of systems with the media containing activated carbon in the removal of petroleum compounds from wastewater. PMID:27148731

  3. MBBR system performance improvement for petroleum hydrocarbon removal using modified media with activated carbon.

    PubMed

    Sayyahzadeh, Amir Hossein; Ganjidoust, Hossein; Ayati, Bita

    2016-01-01

    Moving bed biofilm reactor (MBBR) system has a successful operation in the treatment of different types of wastewater. Since the media, i.e. the place of growth and formation of biofilm, play the main role in the treatment in this system, MBBR systems were operated in the present research with modified Bee-cell media. Activated carbon granules of almond or walnut shells were placed in media pores to improve the treatment of refinery oil wastewater and their operation with MBBR system was compared with the conventional Bee-cell media. In these experiments, the effects of organic loading rate, hydraulic retention time (HRT), media filling ratio (MFR), and activated carbon concentration (ACC) used in the media were investigated on the operation of MBBR systems. The analysis of results estimated the optimal values of HRT, MFR, and ACC used in the media between the studied levels, being equal to 22 h, 50%, and 7.5 g/L, respectively. Under these conditions, total petroleum hydrocarbons removal efficiencies for MBBR systems using Bee-cell media with carbon of almond, carbon of walnut shells, and a carbon-free system were 95 ± 1.17%, 91 ± 1.11%, and 57 ± 1.7%, respectively, which confirms the adsorption ability of systems with the media containing activated carbon in the removal of petroleum compounds from wastewater.

  4. 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

  5. Study on Adsorption Process of Ethanol Vapor to Activated Carbon Fibers

    NASA Astrophysics Data System (ADS)

    Kariya, Keishi; I. I., El-Sharkawy; Suda, Keisuke; B. B., Saha; Kuwahara, Ken; Koyama, Shigeru

    Performance enhancement of adsorption cooling system has been required for commercial use. Therefore, revealing details of adsorption phenomena are important for optimizing adsorber/desorber heat exchanger which is the bottle-neck of the system. This study deals with the experimental investigation of ethanol vapor adsorption on activated carbon fiber (ACF) under equilibrium condition along with one-dimensional transient numerical simulation of heat and mass transfer in the adsorbent bed is also performed. In order to suggest optimizing method for performance improvement, the present study considered the relationships between cooling capacity and system performance inducing parameters, such as cooling water temperature, ACF height and apparent density in the simulation model. Simulation results agreed well with the experimental data and it is found that the cooling capacity can be enhanced by optimizing ACF bed thickness. Simulation results also shows that the temperatures of adsorber and evaporator do not have significant effects on the optimum adsorption cycle time.

  6. Reduction of bromate by granular activated carbon

    SciTech Connect

    Kirisits, M.J.; Snoeyink, V.L.; Kruithof, J.C.

    1998-07-01

    Ozonation of waters containing bromide can lead to the formation of bromate, a probable human carcinogen. Since bromate will be regulated at 10 {micro}g/L by the Stage 1 Disinfectants/Disinfection By-Products Rule, there is considerable interest in finding a suitable method of bromate reduction. Granular activated carbon (GAC) can be used to chemically reduce bromate to bromide, but interference from organic matter and anions present in natural water render this process inefficient. In an effort to improve bromate reduction by GAC, several modifications were made to the GAC filtration process. The use of a biologically active carbon (BAC) filter ahead of a fresh GAC filter with and without preozonation, to remove the biodegradable organic matter, did not substantially improve the bromate removal of the GAC filter. The use of the BAC filter for biological bromate reduction proved to be the most encouraging experiment. By lowering the dissolved oxygen in the influent to the BAC from 8.0 mg/L to 2.0 mg/L, the percent bromate removal increased from 42% to 61%.

  7. REPEATED REDUCTIVE AND OXIDATIVE TREATMENTS ON GRANULAR ACTIVATED CARBON

    EPA Science Inventory

    Fenton oxidation and Fenton oxidation preceded by reduction solutions were applied to granular activated carbon (GAC) to chemically regenerate the adsorbent. No adsorbate was present on the GAC so physicochemical effects from chemically aggressive regeneration of the carbon coul...

  8. Annealing effect on the particle size and chemical composition of activated carbon obtained from vacuum furnace of teak sawdust

    SciTech Connect

    Armynah, B. Tahir, D. Jaya, N.

    2014-09-25

    Activated carbon was produced from sawdust by using physical method in a high temperature vacuum furnace without additional chemical. Fast pyrolysis process was carried out prior in fluidized a bed furnace to produce char before activation process. Experiments were conducted to investigate the influence of various process parameters such as particle size, activation temperature and activation time on the quality of the activated carbon. In addition, the chemical composition studies were done by using x-ray fluorescence (XRF) spectroscopy. The crystallite sizes were calculated by using Scherer equation based on x-ray diffraction (XRD) spectroscopy data. The pyrolysis temperature and time were varied from 600°C to 900°C and from 3 hours to 6 hours, respectively. The particle size of activated carbon was increase with increasing temperature. The composition and crystallite size of the prepared activated carbon was compared with the non-activated carbon. The results indicated that the teak sawdust carbon could be employed as a low cost alternative to produce commercial activated carbon.

  9. Adsorption characteristics of activated carbon fibers (ACFs) for toluene: application in respiratory protection.

    PubMed

    Balanay, Jo Anne G; Bartolucci, Alfred A; Lungu, Claudiu T

    2014-01-01

    Granular activated carbon (GAC) is currently the standard adsorbent in respirators against several gases and vapors because of its efficiency, low cost, and available technology. However, a drawback of GAC due to its granular form is its need for containment, adding weight and bulkiness to respirators. This makes respirators uncomfortable to wear, resulting in poor compliance in their use. Activated carbon fibers (ACF) are considered viable alternative adsorbent materials for developing thinner, light-weight, and efficient respirators because of their larger surface area, lighter weight, and fabric form. This study aims to determine the critical bed depth and adsorption capacity of different types of commercially available ACFs for toluene to understand how thin a respirator can be and the service life of the adsorbents, respectively. ACF in cloth (ACFC) and felt (ACFF) forms with three different surface areas per form were tested. Each ACF type was challenged with six concentrations of toluene (50, 100, 200, 300, 400, 500 ppm) at constant air temperature (23°C), relative humidity (50%), and airflow (16 LPM) at different adsorbent weights and bed depths. Breakthrough data were obtained for each adsorbent using gas chromatography with flame ionization detector. The ACFs' surface areas were measured by an automatic physisorption analyzer. The results showed that ACFC has a lower critical bed depth and higher adsorption capacity compared to ACFF with similar surface area for each toluene concentration. Among the ACF types, ACFC2000 (cloth with the highest measured surface area of 1614 ± 5 m(2)/g) has one of the lowest critical bed depths (ranging from 0.11-0.22 cm) and has the highest adsorption capacity (ranging from 595-878 mg/g). Based on these studied adsorption characteristics, it is concluded that ACF has great potential for application in respiratory protection against toluene, particularly the ACFC2000, which is the best candidate for developing thinner and

  10. Improved granular activated carbon for the stabilization of wastewater pH

    SciTech Connect

    1996-10-01

    Many times the start up of granular activated carbon adsorption systems for the control of organic contaminants in wastewater cm exhibit unacceptable increases in the adscurber effluent pH. Experience shows that the duration of the pH increase ranges from several hours to several days, during which time several hundred bed volumes of water can be discharged with a pH in excess of 9. Laboratory studies have identified the cause of the pH rise as an interaction between the naturally occurring anions and protons ar the water and the carbon surface. The interaction can be described as an ion exchange type of phenomenon, in which the carbon surface sorbs the anions and corresponding hydronium ions from the water. Capacities of the carbon for the anions range from 2 to 9 mg/g GAC, depending upon the water characteristics, the carbon type, the nature of the anion and its influent concentration. These studies have shown de the anion sorption and resulting pH increase is independent of the raw material used for die activated carbon production, e.g. bituminous or sub-bituminous coal, peat, wood or coconut. Also, the pH excursions occur with virgin, reactivated, and acid washed granular carbons. Current pH control technologies focus on adjustment of wastewater pH prior to discharge or recycle of the initial effluent water until the pH increase abates. However, improved water pH control options have been realized by altering the carbon surface rather than the water chemistry. The change to the carbon surface is accomplished through a controlled oxidation process. This process provides a more acidic carbon surface with a reduced affinity for the anions in the waste water. As a result, the pH excursions above 9 are eliminated and the initial effluent from the adsorption system can be discharged without further treatment.

  11. Testing iodized activated carbon filters with non-radioactive methyl iodide. Final report

    SciTech Connect

    Deitz, V.R.; Romans, J.B.

    1980-05-30

    Iodized carbons, impregnated with KIx(KI + xI2), were evaluated for trapping methyl iodide-127. In this method the complete effluent of the carbon is sampled and analyzed continuously. In contrast, the RDT-M16 test procedure counts the carbon and the back-up beds for the accumulated 131 species and no information is obtained for the interaction of the large amount of carrier methyl iodide-127 with the iodized charcoal. The test apparatus to measure the penetration of methyl iodide-127 is described and the calibration procedures are detailed. Results are given for the penetration of methyl iodide-127 through new activated carbons, carbons in service, and exhausted carbons withdrawn from service. The reduction in trapping efficiency with service is accompanied by the development of a maximum in the concentration of methyl iodide-127 during the air purge after the dose period. This behavior has escaped notice with methyl iodide-131 due to the way that test is made. The chromatographic holdup of methyl iodide-127 by carbons in service, together with the subsequent slow desorption step, could result in a dilution of the penetration iodine to acceptable levels under some conditions encountered in plant filter operations.

  12. Seal evaluation and confinement screening criteria for beneficial carbon dioxide storage with enhanced coal bed methane recovery in the Pocahontas Basin, Virginia

    USGS Publications Warehouse

    Grimm, R.P.; Eriksson, K.A.; Ripepi, N.; Eble, C.; Greb, S.F.

    2012-01-01

    The geological storage of carbon dioxide in Appalachian basin coal seams is one possible sink for sequestration of greenhouse gases, with the added benefit of enhanced-coal bed methane (ECBM) recovery. The Pocahontas Basin (part of the central Appalachian Basin) of southwestern Virginia is a major coal bed methane (CBM) province with production mostly from coal beds in the Lower Pennsylvanian Pocahontas and New River formations. As part of the Southeast Regional Carbon Sequestration Partnership's Phase II research program, a CO 2-injection demonstration well was installed into Lower Pennsylvanian coal bed-methane producing strata in southwest Virginia. Samples of siliciclastic lithologies above coal beds in this Oakwood Field well, and from several other cores in the Nora Field were taken to establish a baseline of the basic confinement properties of overlying strata to test seal competency at local and regional scales.Strata above CBM-producing coal beds in the Pocahontas and New River formations consist of dark-gray shales; silty gray shales; heterolithic siltstones, sandstones, and shales; lithic sandstones, and quartzose sandstones. Standard measurements of porosity, permeability and petrography were used to evaluate potential leakage hazards and any possible secondary storage potential for typical lithologies. Both lithic- and quartz-rich sandstones exhibit only minor porosity, with generally low permeability (<0.042mD). Interconnected porosity and permeability are strongly impacted by diverse cementation types and compaction. Analyzed siliciclastic lithologies are considered tight, with limited primary matrix permeability risks for leakage, providing an ensemble of redundant CO 2-ECBM traps.One of the most promising confining intervals above the major coal bed-methane producing interval is the Hensley Shale Member. Analyses of 1500 geophysical logs in southwest Virginia indicate that this unit is moderately thick (>50ft, 15m), laterally continuous (>3000km 2

  13. 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.

  14. Metal-carbon nanocomposites based on activated IR pyrolized polyacrylonitrile

    NASA Astrophysics Data System (ADS)

    Efimov, Mikhail N.; Zhilyaeva, Natalya A.; Vasilyev, Andrey A.; Muratov, Dmitriy G.; Zemtsov, Lev M.; Karpacheva, Galina P.

    2016-05-01

    In this paper we report about new approach to preparation of metal-carbon nanocomposites based on activated carbon. Polyacrylonitrile is suggested as a precursor for Co, Pd and Ru nanoparticles carbon support which is prepared under IR pyrolysis conditions of a precursor. The first part of the paper is devoted to study activated carbon structural characteristics dependence on activation conditions. In the second part the effect of type of metal introduced in precursor on metal-carbon nanocomposite structural characteristics is shown. Prepared AC and nanocomposite samples are characterized by BET, TEM, SEM and X-ray diffraction.

  15. Activated Carbon Composites for Air Separation

    SciTech Connect

    Baker, Frederick S; Contescu, Cristian I; Tsouris, Costas; Burchell, Timothy D

    2011-09-01

    Coal-derived synthesis gas is a potential major source of hydrogen for fuel cells. Oxygen-blown coal gasification is an efficient approach to achieving the goal of producing hydrogen from coal, but a cost-effective means of enriching O2 concentration in air is required. A key objective of this project is to assess the utility of a system that exploits porous carbon materials and electrical swing adsorption to produce an O2-enriched air stream for coal gasification. As a complement to O2 and N2 adsorption measurements, CO2 was used as a more sensitive probe molecule for the characterization of molecular sieving effects. To further enhance the potential of activated carbon composite materials for air separation, work was implemented on incorporating a novel twist into the system; namely the addition of a magnetic field to influence O2 adsorption, which is accompanied by a transition between the paramagnetic and diamagnetic states. The preliminary findings in this respect are discussed.

  16. Treatment of semivolatile compounds in high strength wastes using an anaerobic expanded-bed GAC reactor

    EPA Science Inventory

    The potential of the anaerobic, expanded bed granular activated carbon (GAC) reactor in treating a high strength waste containing RCRA semivolatile organic compounds (VOCs) was studied. Six semivolatiles, orthochlorophenol, nitrobenzene, naphthalene, para-nitrophenol, lindane, a...

  17. Highly porous activated carbons prepared from carbon rich Mongolian anthracite by direct NaOH activation

    NASA Astrophysics Data System (ADS)

    Byamba-Ochir, Narandalai; Shim, Wang Geun; Balathanigaimani, M. S.; Moon, Hee

    2016-08-01

    Highly porous activated carbons (ACs) were prepared from Mongolian raw anthracite (MRA) using sodium hydroxide as an activation agent by varying the mass ratio (powdered MRA/NaOH) as well as the mixing method of chemical agent and powdered MRA. The specific BET surface area and total pore volume of the prepared MRA-based activated carbons (MACs) are in the range of 816-2063 m2/g and of 0.55-1.61 cm3/g, respectively. The pore size distribution of MACs show that most of the pores are in the range from large micropores to small mesopores and their distribution can be controlled by the mass ratio and mixing method of the activating agent. As expected from the intrinsic property of the MRA, the highly graphitic surface morphology of prepared carbons was confirmed from Raman spectra and transmission electron microscopy (TEM) studies. Furthermore the FTIR and XPS results reveal that the preparation of MACs with hydrophobic in nature is highly possible by controlling the mixing conditions of activating agent and powdered MRA. Based on all the results, it is suggested that the prepared MACs could be used for many specific applications, requiring high surface area, optimal pore size distribution, proper surface hydrophobicity as well as strong physical strength.

  18. Toluene vapor capture by activated carbon particles in a dual gas-solid cyclone system.

    PubMed

    Lim, Yun Hui; Ngo, Khanh Quoc; Park, Young Koo; Jo, Young Min

    2012-08-01

    Capturing of odorous compounds such as toluene vapor by a particulate-activated carbon adsorbent was investigated in a gas-solid cyclone, which is one type of mobile beds. The test cyclone was early modified with the post cyclone (PoC) and a spiral flow guide to the vortex finder. The proposed process may contribute to the reduction of gases and dust from industrial exhausts, especially when dealing with a low concentration of odorous elements and a large volume ofdust flow. In this device, the toluene capturing efficiency at a 400 ppm concentration rose up to 77.4% when using activated carbon (AC) particles with a median size of 27.03 microm. A maximum 96% of AC particles could be collected for reuse depending on the size and flow rate. The AC regenerated via thermal treatment showed an adsorption potential up to 66.7% throughout repeated tests.

  19. Modeling moisture diffusivity, activation energy and specific energy consumption of squash seeds in a semi fluidized and fluidized bed drying.

    PubMed

    Chayjan, Reza Amiri; Salari, Kamran; Abedi, Qasem; Sabziparvar, Ali Akbar

    2013-08-01

    This study investigated thin layer drying of squash seeds under semi fluidized and fluidized bed conditions with initial moisture content about 83.99% (d.b.). An experimental fluidized bed dryer was also used in this study. Air temperature levels of 50, 60, 70 and 80 °C were applied in drying samples. To estimate the drying kinetic of squash seed, seven mathematical models were used to fit the experimental data of thin layer drying. Among the applied models, Two-term model has the best performance to estimate the thin layer drying behavior of the squash seeds. Fick's second law in diffusion was used to determine the effective moisture diffusivity of squash seeds. The range of calculated values of effective moisture diffusivity for drying experiments were between 0.160 × 10(-9) and 0.551 × 10(-10) m(2)/s. Moisture diffusivity values decreased as the input air temperature decreased. Activation energy values were found to be between 31.94 and 34.49 kJ/mol for 50 °C to 80 °C, respectively. The specific energy consumption for squash seeds was calculated at the boundary of 0.783 × 10(6) and 2.303 × 10(6) kJ/kg. Increasing in drying air temperature in different bed conditions led to decrease in specific energy value. Results showed that applying the semi fluidized bed condition is more effective for convective drying of squash seeds. The aforesaid drying characteristics are useful to select the best operational point of fluidized bed dryer and to precise design of system.

  20. Modeling moisture diffusivity, activation energy and specific energy consumption of squash seeds in a semi fluidized and fluidized bed drying.

    PubMed

    Chayjan, Reza Amiri; Salari, Kamran; Abedi, Qasem; Sabziparvar, Ali Akbar

    2013-08-01

    This study investigated thin layer drying of squash seeds under semi fluidized and fluidized bed conditions with initial moisture content about 83.99% (d.b.). An experimental fluidized bed dryer was also used in this study. Air temperature levels of 50, 60, 70 and 80 °C were applied in drying samples. To estimate the drying kinetic of squash seed, seven mathematical models were used to fit the experimental data of thin layer drying. Among the applied models, Two-term model has the best performance to estimate the thin layer drying behavior of the squash seeds. Fick's second law in diffusion was used to determine the effective moisture diffusivity of squash seeds. The range of calculated values of effective moisture diffusivity for drying experiments were between 0.160 × 10(-9) and 0.551 × 10(-10) m(2)/s. Moisture diffusivity values decreased as the input air temperature decreased. Activation energy values were found to be between 31.94 and 34.49 kJ/mol for 50 °C to 80 °C, respectively. The specific energy consumption for squash seeds was calculated at the boundary of 0.783 × 10(6) and 2.303 × 10(6) kJ/kg. Increasing in drying air temperature in different bed conditions led to decrease in specific energy value. Results showed that applying the semi fluidized bed condition is more effective for convective drying of squash seeds. The aforesaid drying characteristics are useful to select the best operational point of fluidized bed dryer and to precise design of system. PMID:24425968

  1. Adsorption of N-nitrosodimethylamine precursors by powdered and granular activated carbon.

    PubMed

    Hanigan, David; Zhang, Jinwei; Herckes, Pierre; Krasner, Stuart W; Chen, Chao; Westerhoff, Paul

    2012-11-20

    Activated carbon (AC) has been shown to remove precursors of halogenated disinfection byproducts. Granular and powdered activated carbon (GAC, PAC) were investigated for their potential to adsorb N-nitrosodimethylamine (NDMA) precursors from blends of river water and effluent from a wastewater treatment plant (WWTP). At bench scale, waters were exposed to lignite or bituminous AC, either as PAC in bottle point experiments or as GAC in rapid small-scale column tests (RSSCTs). NDMA formation potential (FP) was used as a surrogate for precursor removal. NDMA FP was reduced by 37, 59, and 91% with 3, 8, and 75 mg/L of one PAC, respectively, with a 4-h contact time. In RSSCTs and in full-scale GAC contactors, NDMA FP removal always exceeded that of the bulk dissolved organic carbon (DOC) and UV absorbance at 254 nm. For example, whereas DOC breakthrough exceeded 90% of its influent concentration after 10,000 bed volumes of operation in an RSSCT, NDMA FP was less than 40% of influent concentration after the same bed life of the GAC. At full or pilot scale, high NDMA FP reduction ranging from >60 to >90% was achieved across GAC contactors, dependent upon the GAC bed life and/or use of a preoxidant (chlorine or ozone). In all experiments, NDMA formation was not reduced to zero, which suggests that although some precursors are strongly sorbed, others are not. This is among the first studies to show that AC is capable of adsorbing NDMA precursors, but further research is needed to better understand NDMA precursor chemical properties (e.g., hydrophobicity, molecular size) and evaluate how best to incorporate this finding into full-scale designs and practice.

  2. Adsorption of N-nitrosodimethylamine precursors by powdered and granular activated carbon.

    PubMed

    Hanigan, David; Zhang, Jinwei; Herckes, Pierre; Krasner, Stuart W; Chen, Chao; Westerhoff, Paul

    2012-11-20

    Activated carbon (AC) has been shown to remove precursors of halogenated disinfection byproducts. Granular and powdered activated carbon (GAC, PAC) were investigated for their potential to adsorb N-nitrosodimethylamine (NDMA) precursors from blends of river water and effluent from a wastewater treatment plant (WWTP). At bench scale, waters were exposed to lignite or bituminous AC, either as PAC in bottle point experiments or as GAC in rapid small-scale column tests (RSSCTs). NDMA formation potential (FP) was used as a surrogate for precursor removal. NDMA FP was reduced by 37, 59, and 91% with 3, 8, and 75 mg/L of one PAC, respectively, with a 4-h contact time. In RSSCTs and in full-scale GAC contactors, NDMA FP removal always exceeded that of the bulk dissolved organic carbon (DOC) and UV absorbance at 254 nm. For example, whereas DOC breakthrough exceeded 90% of its influent concentration after 10,000 bed volumes of operation in an RSSCT, NDMA FP was less than 40% of influent concentration after the same bed life of the GAC. At full or pilot scale, high NDMA FP reduction ranging from >60 to >90% was achieved across GAC contactors, dependent upon the GAC bed life and/or use of a preoxidant (chlorine or ozone). In all experiments, NDMA formation was not reduced to zero, which suggests that although some precursors are strongly sorbed, others are not. This is among the first studies to show that AC is capable of adsorbing NDMA precursors, but further research is needed to better understand NDMA precursor chemical properties (e.g., hydrophobicity, molecular size) and evaluate how best to incorporate this finding into full-scale designs and practice. PMID:23106335

  3. Characterization of Activated Carbons from Oil-Palm Shell by CO2 Activation with No Holding Carbonization Temperature

    PubMed Central

    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. PMID:23737721

  4. Biological activated carbon as tertiary treatment for municipal-industrial wastewater

    SciTech Connect

    Smith, R.P.

    1986-01-01

    Granular Activated Carbon (GAC) as tertiary treatment to secondary biological effluent (trickling filters) was studied at Duck Creek Wastewater Treatment Plant, Garland, Texas. Two sets of pilot plants were operated for a period of eighteen months to determine optimum treatment conditions to obtain best effluent water quality. Performance of the pilot plants far exceeded expectations of pollutant removal capacity which could be achieved by adsorption alone. The sustained high level of treatment efficiency was attributed to biological activity within the GAC beds, generally referred to as Biological Activated Carbon. Increasing Empty Bed Contact Time (EBCT) improved performance, but pretreatments which increased dissolved oxygen concentration prior to GAC contact were more beneficial to effluent water quality than EBCT alone. No significant differences in water quality between pretreatment with oxygen or oxygen-ozone (10 mg/L applied ozone dose) were observed, demonstrating that the main benefit of oxygen-ozone was the oxygen component. Pretreatment with oxygen or oxygen-ozone resulted in nitrification, achieving 85% ammonia reduction, from 10 mg/L to 1 mg/L or less.

  5. Tailoring activated carbons for the development of specific adsorbents of gasoline vapors.

    PubMed

    Vivo-Vilches, J F; Bailón-García, E; Pérez-Cadenas, A F; Carrasco-Marín, F; Maldonado-Hódar, F J

    2013-12-15

    The specific adsorption of oxygenated and aliphatic gasoline components onto activated carbons (ACs) was studied under static and dynamic conditions. Ethanol and n-octane were selected as target molecules. A highly porous activated carbon (CA) was prepared by means of two processes: carbonization and chemical activation of olive stone residues. Different types of oxygenated groups, identified and quantified by TPD and XPS, were generated on the CA surface using an oxidation treatment with ammonium peroxydisulfate and then selectively removed by thermal treatments, as confirmed by TPD results. Chemical and porous transformations were carefully analyzed throughout these processes and related to their VOC removal performance. The analysis of the adsorption process under static conditions and the thermal desorption of VOCs enabled us to determine the total adsorption capacity and regeneration possibilities. Breakthrough curves obtained for the adsorption process carried out under dynamic conditions provided information about the mass transfer zone in each adsorption bed. While n-octane adsorption is mainly determined by the porosity of activated carbons, ethanol adsorption is related to their surface chemistry, and in particular is enhanced by the presence of carboxylic acid groups.

  6. Low temperature regeneration of activated carbons using microwaves: revising conventional wisdom.

    PubMed

    Calışkan, E; Bermúdez, J M; Parra, J B; Menéndez, J A; Mahramanlıoğlu, M; Ania, C O

    2012-07-15

    The purpose of this work was to explore the application of microwaves for the low temperature regeneration of activated carbons saturated with a pharmaceutical compound (promethazine). Contrary to expectations, microwave-assisted regeneration did not lead to better results than those obtained under conventional electric heating. At low temperatures the regeneration was incomplete either under microwave and conventional heating, being this attributed to the insufficient input energy. At mild temperatures, a fall in the adsorption capacity upon cycling was obtained in both devices, although this was much more pronounced for the microwave. These results contrast with previous studies on the benefits of microwaves for the regeneration of carbon materials. The fall in the adsorption capacity after regeneration was due to the thermal cracking of the adsorbed molecules inside the carbon porous network, although this effect applies to both devices. When microwaves are used, along with the thermal heating of the carbon bed, a fraction of the microwave energy seemed to be directly used in the decomposition of promethazine through the excitation of the molecular bonds by microwaves (microwave-lysis). These results point out that the nature of the adsorbate and its ability to interact with microwave are key factors that control the application of microwaves for regeneration of exhausted activated carbons.

  7. Record Methane Storage in Monolithic and Powdered Activated Carbons

    NASA Astrophysics Data System (ADS)

    Soo, Yuchoong; Nordwald, E.; Hester, B.; Romanos, J.; Isaacson, B.; Stalla, D.; Moore, D.; Kraus, M.; Burress, J.; Dohnke, E.; Pfeifer, P.

    2010-03-01

    The Alliance for Collaborative Research in Alternative Fuel Technology (ALL-CRAFT) has developed activated carbons from corn cob as adsorbent materials for methane gas storage by physisorption at low pressures. KOH activated carbons were compressed into carbon monolith using chemical binders. High pressure methane isotherms up to 250 bar at room temperature on monolithic and powdered activated carbons were measured gravimetrically and volumetrically. Record methane storage capacities of 250 g CH4/kg carbon and 130 g CH4/liter carbon at 35 bar and 293 K have been achieved. BET surface area, porosity, and pore size distributions were measured from sub-critical nitrogen isotherms. Pore entrances were characterized using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). A prototype adsorbed natural gas (ANG) tank, loaded with carbon monoliths, was tested in Kansas City.

  8. Synthesis of fluorescent carbon nanoparticles directly from active carbon via a one-step ultrasonic treatment

    SciTech Connect

    Li, Haitao; He, Xiaodie; Liu, Yang; Yu, Hang; Kang, Zhenhui; Lee, Shuit-Tong

    2011-01-15

    Water-soluble fluorescent carbon nanoparticles were synthesized directly from active carbon by a one-step hydrogen peroxide-assisted ultrasonic treatment. The carbon nanoparticles were characterized by transmission electron microscopy, optical fluorescent microscopy, fluorescent spectroscopy, Fourier transform infrared spectroscopy and ultraviolet-visible spectrophotometer. The results showed that the surface of carbon nanoparticles was rich of hydroxyl groups resulting in high hydrophilicity. The carbon nanoparticles could emit bright and colorful photoluminescence covering the entire visible-to-near infrared spectral range. Furthermore, these carbon nanoparticles also had excellent up-conversion fluorescent properties.

  9. User-oriented batch reactor solutions to the homogeneous surface diffusion model for different activated carbon dosages.

    PubMed

    Zhang, Qiong; Crittenden, John; Hristovski, Kiril; Hand, David; Westerhoff, Paul

    2009-04-01

    This paper presents a simplified approach and user-oriented solutions to the homogeneous surface diffusion model (HSDM) equations for determining the surface diffusivity using a batch reactor system. Once the surface diffusivity is known, this model could also be used to estimate the performance of activated carbon (AC) applications as a function of contact time. In addition, fixed-bed performance can be predicted using the user-oriented solutions to the HSDM for fixed beds. The step-by-step procedure for determining surface diffusion coefficients of an activated carbon adsorber, which was initially developed by Hand, Crittenden and Thacker in 1983 for a carbon dose where C(equilibrium)/C(0)=0.5, is modified to allow calculations for different carbon dosages. This modification provides solutions to the HSDM equations for different activated carbon dosages. The solutions to the HSDM framework are provided as simplified algebraic equations suitable for quick and easy estimations of D(S). The excel spread sheet is provided in the supplemental information and a detailed example is discussed. PMID:19249812

  10. [Effects of different fertilizer application on soil active organic carbon].

    PubMed

    Zhang, Rui; Zhang, Gui-Long; Ji, Yan-Yan; Li, Gang; Chang, Hong; Yang, Dian-Lin

    2013-01-01

    The variation characteristics of the content and components of soil active organic carbon under different fertilizer application were investigated in samples of calcareous fluvo-aquic soil from a field experiment growing winter wheat and summer maize in rotation in the North China Plain. The results showed that RF (recommended fertilization), CF (conventional fertilization) and NPK (mineral fertilizer alone) significantly increased the content of soil dissolved organic carbon and easily oxidized organic carbon by 24.92-38.63 mg x kg(-1) and 0.94-0.58 mg x kg(-1) respectively compared to CK (unfertilized control). The soil dissolved organic carbon content under OM (organic manure) increased greater than those under NPK and single fertilization, soil easily oxidized organic carbon content under OM and NPK increased greater than that under single chemical fertilization. OM and NPK showed no significant role in promoting the soil microbial biomass carbon, but combined application of OM and NPK significantly increased the soil microbial biomass carbon content by 36.06% and 20.69%, respectively. Soil easily oxidized organic carbon, dissolved organic carbon and microbial biomass carbon accounted for 8.41% - 14.83%, 0.47% - 0.70% and 0.89% - 1.20% of the total organic carbon (TOC), respectively. According to the results, the fertilizer application significantly increased the proportion of soil dissolved organic carbon and easily oxidized organic carbon, but there was no significant difference in the increasing extent of dissolved organic carbon. The RF and CF increased the proportion of soil easily oxidized organic carbon greater than OM or NPK, and significantly increased the proportion of microbial biomass carbon. OM or RF had no significant effect on the proportion of microbial biomass carbon. Therefore, in the field experiment, appropriate application of organic manure and chemical fertilizers played an important role for the increase of soil active organic carbon

  11. [Effects of different fertilizer application on soil active organic carbon].

    PubMed

    Zhang, Rui; Zhang, Gui-Long; Ji, Yan-Yan; Li, Gang; Chang, Hong; Yang, Dian-Lin

    2013-01-01

    The variation characteristics of the content and components of soil active organic carbon under different fertilizer application were investigated in samples of calcareous fluvo-aquic soil from a field experiment growing winter wheat and summer maize in rotation in the North China Plain. The results showed that RF (recommended fertilization), CF (conventional fertilization) and NPK (mineral fertilizer alone) significantly increased the content of soil dissolved organic carbon and easily oxidized organic carbon by 24.92-38.63 mg x kg(-1) and 0.94-0.58 mg x kg(-1) respectively compared to CK (unfertilized control). The soil dissolved organic carbon content under OM (organic manure) increased greater than those under NPK and single fertilization, soil easily oxidized organic carbon content under OM and NPK increased greater than that under single chemical fertilization. OM and NPK showed no significant role in promoting the soil microbial biomass carbon, but combined application of OM and NPK significantly increased the soil microbial biomass carbon content by 36.06% and 20.69%, respectively. Soil easily oxidized organic carbon, dissolved organic carbon and microbial biomass carbon accounted for 8.41% - 14.83%, 0.47% - 0.70% and 0.89% - 1.20% of the total organic carbon (TOC), respectively. According to the results, the fertilizer application significantly increased the proportion of soil dissolved organic carbon and easily oxidized organic carbon, but there was no significant difference in the increasing extent of dissolved organic carbon. The RF and CF increased the proportion of soil easily oxidized organic carbon greater than OM or NPK, and significantly increased the proportion of microbial biomass carbon. OM or RF had no significant effect on the proportion of microbial biomass carbon. Therefore, in the field experiment, appropriate application of organic manure and chemical fertilizers played an important role for the increase of soil active organic carbon

  12. Study on preparation of water hyacinth-based activated carbon for pulp and paper mill wastewater treatment.

    PubMed

    Boonpoke, Anusorn

    2015-09-01

    Mulberry pulp and paper mills produce high chemical- and organic matter containing waste water in Thailand. Many of the mills are not equipped with wastewater treatment unit; their untreated effluent is directly discharged into recipient water resources. The effluent constituents are well recognized as acute and chronic pollutants that are hazardous to the environment. The present study aimed to investigate the utilization of an activated carbon from a low-cost material and to examine its adsorption performance using batch and fixed-bed adsorption. Water hyacinth was used as a raw material for activated carbon production via a chemical activation method. The results showed that water hyacinth-based activated carbon (WHAC) provided a high surface area of 912-1,066 m2g(-1) and exhibited micropore structure. Based on the Freundlich fit, the maximum adsorption capacity of COD and color was 4.52 mgg(-1) and 13.57 Pt-Cog(-1), respectively. The fixed bed adsorption provided maximum removal efficiency of 91.70 and 92.62% for COD and color, respectively. A continuous adsorption data agreed well with the Thomas kinetic model. In summary, water hyacinth can be used as a low-cost material for activated carbon production with high removal efficiency of COD and color for pulp and paper mill wastewater treatment.

  13. Study on preparation of water hyacinth-based activated carbon for pulp and paper mill wastewater treatment.

    PubMed

    Boonpoke, Anusorn

    2015-09-01

    Mulberry pulp and paper mills produce high chemical- and organic matter containing waste water in Thailand. Many of the mills are not equipped with wastewater treatment unit; their untreated effluent is directly discharged into recipient water resources. The effluent constituents are well recognized as acute and chronic pollutants that are hazardous to the environment. The present study aimed to investigate the utilization of an activated carbon from a low-cost material and to examine its adsorption performance using batch and fixed-bed adsorption. Water hyacinth was used as a raw material for activated carbon production via a chemical activation method. The results showed that water hyacinth-based activated carbon (WHAC) provided a high surface area of 912-1,066 m2g(-1) and exhibited micropore structure. Based on the Freundlich fit, the maximum adsorption capacity of COD and color was 4.52 mgg(-1) and 13.57 Pt-Cog(-1), respectively. The fixed bed adsorption provided maximum removal efficiency of 91.70 and 92.62% for COD and color, respectively. A continuous adsorption data agreed well with the Thomas kinetic model. In summary, water hyacinth can be used as a low-cost material for activated carbon production with high removal efficiency of COD and color for pulp and paper mill wastewater treatment. PMID:26521558

  14. Systematic approach to determination of maximum achievable capture capacity via leaching and carbonation processes for alkaline steelmaking wastes in a rotating packed bed.

    PubMed

    Pan, Shu-Yuan; Chiang, Pen-Chi; Chen, Yi-Hung; Chen, Chun-Da; Lin, Hsun-Yu; Chang, E-E

    2013-01-01

    Accelerated carbonation of basic oxygen furnace slag (BOFS) coupled with cold-rolling wastewater (CRW) was performed in a rotating packed bed (RPB) as a promising process for both CO2 fixation and wastewater treatment. The maximum achievable capture capacity (MACC) via leaching and carbonation processes for BOFS in an RPB was systematically determined throughout this study. The leaching behavior of various metal ions from the BOFS into the CRW was investigated by a kinetic model. In addition, quantitative X-ray diffraction (QXRD) using the Rietveld method was carried out to determine the process chemistry of carbonation of BOFS with CRW in an RPB. According to the QXRD results, the major mineral phases reacting with CO2 in BOFS were Ca(OH)2, Ca2(HSiO4)(OH), CaSiO3, and Ca2Fe1.04Al0.986O5. Meanwhile, the carbonation product was identified as calcite according to the observations of SEM, XEDS, and mappings. Furthermore, the MACC of the lab-scale RPB process was determined by balancing the carbonation conversion and energy consumption. In that case, the overall energy consumption, including grinding, pumping, stirring, and rotating processes, was estimated to be 707 kWh/t-CO2. It was thus concluded that CO2 capture by accelerated carbonation of BOFS could be effectively and efficiently performed by coutilizing with CRW in an RPB. PMID:24236803

  15. Systematic approach to determination of maximum achievable capture capacity via leaching and carbonation processes for alkaline steelmaking wastes in a rotating packed bed.

    PubMed

    Pan, Shu-Yuan; Chiang, Pen-Chi; Chen, Yi-Hung; Chen, Chun-Da; Lin, Hsun-Yu; Chang, E-E

    2013-01-01

    Accelerated carbonation of basic oxygen furnace slag (BOFS) coupled with cold-rolling wastewater (CRW) was performed in a rotating packed bed (RPB) as a promising process for both CO2 fixation and wastewater treatment. The maximum achievable capture capacity (MACC) via leaching and carbonation processes for BOFS in an RPB was systematically determined throughout this study. The leaching behavior of various metal ions from the BOFS into the CRW was investigated by a kinetic model. In addition, quantitative X-ray diffraction (QXRD) using the Rietveld method was carried out to determine the process chemistry of carbonation of BOFS with CRW in an RPB. According to the QXRD results, the major mineral phases reacting with CO2 in BOFS were Ca(OH)2, Ca2(HSiO4)(OH), CaSiO3, and Ca2Fe1.04Al0.986O5. Meanwhile, the carbonation product was identified as calcite according to the observations of SEM, XEDS, and mappings. Furthermore, the MACC of the lab-scale RPB process was determined by balancing the carbonation conversion and energy consumption. In that case, the overall energy consumption, including grinding, pumping, stirring, and rotating processes, was estimated to be 707 kWh/t-CO2. It was thus concluded that CO2 capture by accelerated carbonation of BOFS could be effectively and efficiently performed by coutilizing with CRW in an RPB.

  16. [Activity of oxidation-reduction enzymes in endotheliocytes of the intestinal hemomicrocirculatory bed under normal conditions and in portal hypertension].

    PubMed

    Gaĭvoronskiĭ, I V; Tikhonova, L P; Chepur, S V; Nichiporuk, G I

    1997-01-01

    An original quantitative examination of oxidation-reduction enzymes activity in endotheliocytes of hemomicroclrculatory vessels of jejunum and rectum submucosal base in normal state and in portal hypertension was performed by the authors. Comparative analysis of the activity of the enzymes studied revealed different metabolic processes intensity in these organs, dependent on current hemodynamic conditions. Cytochemical changes in hemomicrocirculatory bed are consistent with structural reorganizations that arise in the wall of vessels studied, consist of several phases and may be used as an assessment criterion for defining the portal hypertension stage.

  17. Bed bugs.

    PubMed

    Foulke, Galen T; Anderson, Bryan E

    2014-09-01

    The term bed bug is applied to 2 species of genus Cimex: lectularius describes the common or temperate bed bug, and hemipterus its tropical cousin. Cimex lectularius is aptly named; its genus and species derive from the Latin words for bug and bed, respectively. Though the tiny pest is receiving increased public attention and scrutiny, the bed bug is hardly a new problem. PMID:25577850

  18. 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.

  19. The evaluation of empty bed contact time on the biodegradation of pentachlorophenol using an anaerobic GAC fluidized bed

    SciTech Connect

    Wilson, G.J.; Khodadoust, A.P.; Suidan, M.T.; Wagner, J.A.; Brenner, R.C.

    1994-12-31

    The objective of this research is to evaluate the effects of decreasing the empty-bed contact time (EBCT) on pentachlorophenol and its intermediates utilizing an anaerobic granular activated carbon (GAC) fluidized bed. The bioreactor A was fed an 100 mg/l influent concentration of PCP. EBCTs of 1.167 to 0.292 days for reactor A resulted in a PCP reduction greater than 99%. In addition, an equimolar conversion of PCP to monochlorophenol was observed.

  20. 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

  1. Utilization of date stones for production of activated carbon using phosphoric acid

    SciTech Connect

    Haimour, N.M. . E-mail: nomanhaimour@hotmail.com; Emeish, S. . E-mail: s_emiesh@yahoo.com

    2006-07-01

    Date stone wastes have been utilized for production of activated carbon by chemical activation with phosphoric acid using a fluidized-bed reactor. The effects of the activation time, activation temperature, impregnation ratio, and particle size on the yield and the adsorptive capacity towards iodine were studied. The yield and the quality of the activated carbon prepared by using H{sub 3}PO{sub 4} were compared with that prepared from date stones using the same equipment, and under similar conditions by using ZnCl{sub 2} as an oxidizing agent. The maximum value of the iodine number of the activated carbon produced using H{sub 3}PO{sub 4} in this work was about 495 under the following conditions: impregnation ratio 0.4, activation time 60 min, activation temperature 800 deg. C, particle size 0.60 mm. The iodine number for the produced activated carbon was higher when phosphoric acid was used, compared to that when zinc chloride was used as impregnation reagent; however, the yield obtained when H{sub 3}PO{sub 4} was used was lower than the yield when ZnCl{sub 2} was used. The iodine number increases significantly with increasing the activation temperature. By increasing the impregnation ratio at the same temperature, the iodine number decreased sharply and an oscillation is noticed for all the cases but it was clearer at 800 deg. C. The average variation of the iodine number for the whole range of particle size used in this work is {+-}10%.

  2. Bed rest in pregnancy.

    PubMed

    Bigelow, Catherine; Stone, Joanne

    2011-01-01

    The use of bed rest in medicine dates back to Hippocrates, who first recommended bed rest as a restorative measure for pain. With the formalization of prenatal care in the early 1900s, maternal bed rest became a standard of care, especially toward the end of pregnancy. Antepartum bed rest is a common obstetric management tool, with up to 95% of obstetricians utilizing maternal activity restriction in some way in their practice. Bed rest is prescribed for a variety of complications of pregnancy, from threatened abortion and multiple gestations to preeclampsia and preterm labor. Although the use of bed rest is pervasive, there is a paucity of data to support its use. Additionally, many well-documented adverse physical, psychological, familial, societal, and financial effects have been discussed in the literature. There have been no complications of pregnancy for which the literature consistently demonstrates a benefit to antepartum bed rest. Given the well-documented adverse effects of bed rest, disruption of social relationships, and financial implications of this intervention, there is a real need for scientific investigation to establish whether this is an appropriate therapeutic modality. Well-designed randomized, controlled trials of bed rest versus normal activity for various complications of pregnancy are required to lay this debate to rest once and for all. PMID:21425272

  3. Tracking small mountainous river derived terrestrial organic carbon across the active margin marine environment

    NASA Astrophysics Data System (ADS)

    Childress, L. B.; Blair, N. E.; Orpin, A. R.

    2015-12-01

    Active margins are particularly efficient in the burial of organic carbon due to the close proximity of highland sources to marine sediment sinks and high sediment transport rates. Compared with passive margins, active margins are dominated by small mountainous river systems, and play a unique role in marine and global carbon cycles. Small mountainous rivers drain only approximately 20% of land, but deliver approximately 40% of the fluvial sediment to the global ocean. Unlike large passive margin systems where riverine organic carbon is efficiently incinerated on continental shelves, small mountainous river dominated systems are highly effective in the burial and preservation of organic carbon due to the rapid and episodic delivery of organic carbon sourced from vegetation, soil, and rock. To investigate the erosion, transport, and burial of organic carbon in active margin small mountainous river systems we use the Waipaoa River, New Zealand. The Waipaoa River, and adjacent marine depositional environment, is a system of interest due to a large sediment yield (6800 tons km-2 yr-1) and extensive characterization. Previous studies have considered the biogeochemistry of the watershed and tracked the transport of terrestrially derived sediment and organics to the continental shelf and slope by biogeochemical proxies including stable carbon isotopes, lignin phenols, n-alkanes, and n-fatty acids. In this work we expand the spatial extent of investigation to include deep sea sediments of the Hikurangi Trough. Located in approximately 3000 m water depth 120 km from the mouth of the Waipaoa River, the Hikurangi Trough is the southern extension of the Tonga-Kermadec-Hikurangi subduction system. Piston core sediments collected by the National Institute of Water and Atmospheric Research (NIWA, NZ) in the Hikurangi Trough indicate the presence of terrestrially derived material (lignin phenols), and suggest a continuum of deposition, resuspension, and transport across the margin

  4. On the reactive adsorption of ammonia on activated carbons modified by impregnation with inorganic compounds.

    PubMed

    Bandosz, Teresa J; Petit, Camille

    2009-10-15

    Ammonia adsorption was studied under dynamic conditions, at room temperature, on activated carbons of different origins (coal-based, wood-based and coconut-shell-based carbons) before and after their impregnation with various inorganic compounds including metal chlorides, metal oxides and polycations. The role of humidity was evaluated by running tests in both dry and moist conditions. Adsorbents were analyzed before and after exposure to ammonia by thermal analyses, sorption of nitrogen, potentiometric titration, X-ray diffraction and FTIR spectroscopy. Results of breakthrough tests show significant differences in terms of adsorption capacity depending on the parent carbon, the impregnates and the experimental conditions. It is found that surface chemistry governs ammonia adsorption on the impregnated carbons. More precisely, it was demonstrated that a proper combination of the surface pH, the strength, type and amount of functional groups present on the adsorbents' surface is a key point in ammonia uptake. Water can have either positive or negative effects on the performance of adsorbents. It can enhance NH(3) adsorption capacity since it favors ammonia dissolution and thus enables reaction between ammonium ions and carboxylic groups from the carbons' surface. On the other hand, water can also reduce the performance from the strength of adsorption standpoint. It promotes dissolution of ammonia and that ammonia is first removed from the system when the adsorbent bed is purged with air. Ammonia, besides adsorption by van der Waals forces and dissolution in water, is also retained on the surface via reactive mechanisms such as acid-base reactions (Brønsted and Lewis) or complexation. Depending on the materials used and the experimental conditions, 6-47% ammonia adsorbed is strongly retained on the surface even when the bed is purged with air. PMID:19615690

  5. On the reactive adsorption of ammonia on activated carbons modified by impregnation with inorganic compounds

    SciTech Connect

    Bandosz, T.J.; Petit, C.

    2009-10-15

    Ammonia adsorption was studied under dynamic conditions, at room temperature, on activated carbons of different origins (coal-based, wood-based and coconut-shell-based carbons) before and after their impregnation with various inorganic compounds including metal chlorides, metal oxides and polycations. The role of humidity was evaluated by running tests in both dry and moist conditions. Adsorbents were analyzed before and after exposure to ammonia by thermal analyses, sorption of nitrogen, potentiometric titration, X-ray diffraction and FTIR spectroscopy. Results of breakthrough tests show significant differences in terms of adsorption capacity depending on the parent carbon, the impregnates and the experimental conditions. It is found that surface chemistry governs ammonia adsorption on the impregnated carbons. More precisely, it was demonstrated that a proper combination of the surface pH, the strength, type and amount of functional groups present on the adsorbents' surface is a key point in ammonia uptake. Water can have either positive or negative effects on the performance of adsorbents. It can enhance NH{sub 3} adsorption capacity since it favors ammonia dissolution and thus enables reaction between ammonium ions and carboxylic groups from the carbons' surface. On the other hand, water can also reduce the performance from the strength of adsorption standpoint. It promotes dissolution of ammonia and that ammonia is first removed from the system when the adsorbent bed is purged with air. Ammonia, besides adsorption by van der Waals forces and dissolution in water, is also retained on the surface via reactive mechanisms such as acid-base reactions (Bronsted and Lewis) or complexation. Depending on the materials used and the experimental conditions, 6-47% ammonia adsorbed is strongly retained on the surface even when the bed is purged with air.

  6. Effect of three day bed-rest on circulatory and hormonal responses to active orthostatic test in endurance trained athletes and untrained subjects

    NASA Technical Reports Server (NTRS)

    Kubala, P.; Smorawinski, J.; Kaciuba-Uscilko, H.; Nazar, K.; Bicz, B.; Greenleaf, J. E.

    1996-01-01

    Circulatory and hormonal parameters were measured in endurance-trained athletes and control subjects during orthostatic tolerance tests conducted prior to and after three days of bed rest. Heart rate and blood pressure changes due to bed rest appeared to be the same in both groups. Hormonal changes, however, were different between the two groups, with the athletes having decreased sympathoadrenal activity and increased plasma renin activity. Untrained subjects had changes in cortisol secretion only.

  7. Preparation of nitrogen-enriched activated carbons from brown coal

    SciTech Connect

    Robert Pietrzak; Helena Wachowska; Piotr Nowicki

    2006-05-15

    Nitrogen-enriched activated carbons were prepared from a Polish brown coal. Nitrogen was introduced from urea at 350{sup o}C in an oxidizing atmosphere both to carbonizates obtained at 500-700{sup o}C and to activated carbons prepared from them. The activation was performed at 800{sup o}C with KOH in argon. It has been observed that the carbonization temperature determines the amount of nitrogen that is incorporated (DC5U, 8.4 wt % N{sup daf}; DC6U, 6.3 wt % N{sup daf}; and DC7U, 5.4 wt % N{sup daf}). X-ray photoelectron spectroscopy (XPS) measurements have shown that nitrogen introduced both at the stage of carbonizates and at the stage of activated carbons occurs mainly as -6, -5, and imine, amine and amide groups. On the other hand, the activation of carbons enriched with nitrogen results in the formation of pyridonic nitrogen and N-Q. The introduction of nitrogen at the activated carbon stage leads to a slight decrease in surface area. It has been proven that the most effective way of preparing microporous activated carbons enriched with nitrogen to a considerable extent and having high surface area ({approximately} 3000 m{sup 2}/g) is the following: carbonization - activation - reaction with urea. 40 refs., 1 fig., 6 tabs.

  8. Acoustical Evaluation of Carbonized and Activated Cotton Nonwovens

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The process of manufacturing a carbonized and activated nonwoven made by cotton fiber was investigated in this paper. The study was focused on the acoustic application and nonwoven composites with cotton nonwoven as a base layer and glass fiber nonwoven, cotton nonwoven, and carbonized and activated...

  9. A Magnesium-Activated Carbon Hybrid Capacitor

    SciTech Connect

    Yoo, HD; Shterenberg, I; Gofer, Y; Doe, RE; Fischer, CC; Ceder, G; Aurbach, D

    2013-12-11

    Prototype cells of hybrid capacitor were developed, comprising activated carbon (AC) cloth and magnesium (Mg) foil as the positive and negative electrodes, respectively. The electrolyte solution included ether solvent (TBF) and a magnesium organo-halo-aluminate complex 0.25 M Mg2Cl3+-Ph2AlCl2-. In this solution Mg can be deposited/dissolved reversibly for thousands of cycles with high reversibility (100% cycling efficiency). The main barrier for integrating porous AC electrodes with this electrolyte solution was the saturation of the pores with the large ions in the AC prior to reaching the potential limit. This is due to the existence of bulky Mg and Al based ionic complexes consisting Cl, alkyl or aryl (R), and THF ligands. This problem was resolved by adding 0.5 M of lithium chloride (LiCl), thus introducing smaller ionic species to the solution. This Mg hybrid capacitor system demonstrated a stable cycle performance for many thousands of cycles with a specific capacitance of 90 Fg(-1) for the AC positive electrodes along a potential range of 2.4 V. (C) 2014 The Electrochemical Society. All rights reserved.

  10. Application of sulfur impregnated activated carbons for the control of mercury emissions

    SciTech Connect

    Vidic, R.D.; Liu, W.; Brown, T.D.

    1998-12-31

    The dynamics of granular activated carbon (GAC) adsorbers for the uptake of vapor-phase mercury was evaluated as a function of temperature, influent mercury concentration, and empty bed contact time. Sulfur-impregnated carbons exhibited enhanced mercury removal efficiency over virgin carbon due to formation of mercuric sulfide on the carbon surface. The effect of the sulfur impregnation method on mercury removal efficiency was examined through experiments conducted on commercially available sulfur-impregnated carbon (HGR) and carbon impregnated with sulfur in the laboratory (BPL-S). Although HGR and BPL-S possess similar sulfur contents, BPL-S is impregnated at a higher temperature which promotes a more uniform distribution of sulfur in the GAC pore structure. At low influent mercury concentrations and low temperatures, HGR and BPL-S performed similarly in the removal of mercury vapor. However, as the temperature was increased above the melting point of sulfur, the performance of HGR deteriorated significantly, while the performance of BPL-S slightly improved. For both HGR and BPL-S, the observed dynamic mercury adsorptive capacities were far below the capacities predicted by the stoichiometry of mercuric sulfide formation. In HGR carbon the sulfur is very accessible, but agglomeration which occurs at high temperatures causes the sulfur to become relatively unreactive. In BPL-S carbon, on the other hand, the sulfur remains in a highly reactive form, but its location deep in the internal pores makes it relatively inaccessible and susceptible to blockage by HgS formation. Impregnation temperature and the initial sulfur to carbon ratio (SCR) during the impregnation are the two key control parameters for the preparation of these new (BPL-S) sorbents. Higher impregnation temperatures can significantly enhance mercury removal capacity for adsorbents derived either from virgin or re-generated activated carbons. Large fraction of active sulfur atoms that are created at

  11. Disinfection by-products and microbial contamination in the treatment of pool water with granular activated carbon.

    PubMed

    Uhl, W; Hartmann, C

    2005-01-01

    For swimming pools, it is generally agreed that free chlorine levels have to be maintained to guarantee adequate disinfection. Recommended free chlorine levels can vary between 0.3 and 0.6 mg/L in Germany and up to 3 mg/L in other countries. Bathers introduce considerable amounts of organic matter, mainly in the form of such as urine and sweat, into the pool water. As a consequence, disinfection byproducts (DBPs) are formed. Regulations in Germany recommend levels of combined chlorine of less than 0.2 mg/L and levels of trihalomethanes (THMs) of less than 20 microg/L. Haloacetic acids (HAAs), haloacetonitriles (HANs), chloropicrin and chloral hydrate are also detected in considerable amounts. However, these compounds are not regulated yet. Swimming pool staff and swimmers, especially athletes, are primarily exposed to these byproducts by inhalation and/or dermal uptake. In Germany, new regulations for swimming pool water treatment generally require the use of activated carbon. In this project, three different types of granular activated carbon (GAC) (one standard GAC, two catalytic GACs) are compared for their long time behaviour in pool water treatment. In a pilot plant operated with real swimming pool water, production and removal of disinfection byproducts (THMs, HAAs, AOXs), of biodegradable substances (AOC), of bacteria (Pseudomonas aeruginosa, Legionella, coliforms, HPC) as well as the removal of chlorine and chloramines are monitored as function of GAC bed depth. Combined chlorine penetrates deeper in the filter bed than free chlorine does. However, both, free and combined chlorine removal efficiencies decrease over the time of filter operation. The decreases of removal efficiencies are also observed for parameters such as dissolved organic carbon, spectral absorption coefficient, adsorbable organic carbon and most of the disinfection byproducts. However, THMs, especially chloroform are produced in the filter bed. The GAC beds were contaminated microbially

  12. 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.

  13. Ozone Removal by Filters Containing Activated Carbon: A Pilot Study

    SciTech Connect

    Fisk, William; Spears, Mike; Sullivan, Douglas; Mendell, Mark

    2009-09-01

    This study evaluated the ozone removal performance of moderate-cost particle filters containing activated carbon when installed in a commercial building heating, ventilating, and air conditioning (HVAC) system. Filters containing 300 g of activated carbon per 0.09 m2 of filter face area were installed in two 'experimental' filter banks within an office building located in Sacramento, CA. The ozone removal performance of the filters was assessed through periodic measurements of ozone concentrations in the air upstream and downstream of the filters. Ozone concentrations were also measured upstream and downstream of a 'reference' filter bank containing filters without any activated carbon. The filter banks with prefilters containing activated carbon were removing 60percent to 70percent of the ozone 67 and 81 days after filter installation. In contrast, there was negligible ozone removal by the reference filter bank without activated carbon.

  14. Fractal analysis of granular activated carbons using isotherm data

    SciTech Connect

    Khalili, N.R.; Pan, M.; Sandi, G.

    1997-08-01

    Utilization of adsorption on solid surfaces was exercised for the first time in 1785. Practical application of unactivated carbon filters, and powdered carbon were first demonstrated in the American water treatment plant, and a municipal treatment plant in New Jersey, in 1883 and 1930, respectively. The use of activated carbon became widespread in the next few decades. At present, adsorption on carbons has a wide spread application in water treatment and removal of taste, odor, removal of synthetic organic chemicals, color-forming organics, and desinfection by-products and their naturally occurring precursors. This paper presents an analysis of the surface fractal dimension and adsorption capacity of a group of carbons.

  15. Isolation and metagenomic characterization of bacteria associated with calcium carbonate and struvite precipitation in a pure moving bed biofilm reactor-membrane bioreactor.

    PubMed

    Gonzalez-Martinez, A; Leyva-Díaz, J C; Rodriguez-Sanchez, A; Muñoz-Palazon, B; Rivadeneyra, A; Poyatos, J M; Rivadeneyra, M A; Martinez-Toledo, M V

    2015-01-01

    A bench-scale pure moving bed bioreactor-membrane bioreactor (MBBR-MBR) used for the treatment of urban wastewater was analyzed for the identification of bacterial strains with the potential capacity for calcium carbonate and struvite biomineral formation. Isolation of mineral-forming strains on calcium carbonate and struvite media revealed six major colonies with a carbonate or struvite precipitation capacity in the biofouling on the membrane surface and showed that heterotrophic bacteria with the ability to precipitate calcium carbonate and struvite constituted ~7.5% of the total platable bacteria. These belonged to the genera Lysinibacillus, Trichococcus, Comamomas and Bacillus. Pyrosequencing analysis of the microbial communities in the suspended cells and membrane biofouling showed a high degree of similarity in all the samples collected with respect to bacterial assemblage. The study of operational taxonomic units (OTUs) identified through pyrosequencing suggested that ~21% of the total bacterial community identified in the biofouling could potentially form calcium carbonate or struvite crystals in the pure MBBR-MBR system used for the treatment of urban wastewater.

  16. Isolation and metagenomic characterization of bacteria associated with calcium carbonate and struvite precipitation in a pure moving bed biofilm reactor-membrane bioreactor.

    PubMed

    Gonzalez-Martinez, A; Leyva-Díaz, J C; Rodriguez-Sanchez, A; Muñoz-Palazon, B; Rivadeneyra, A; Poyatos, J M; Rivadeneyra, M A; Martinez-Toledo, M V

    2015-01-01

    A bench-scale pure moving bed bioreactor-membrane bioreactor (MBBR-MBR) used for the treatment of urban wastewater was analyzed for the identification of bacterial strains with the potential capacity for calcium carbonate and struvite biomineral formation. Isolation of mineral-forming strains on calcium carbonate and struvite media revealed six major colonies with a carbonate or struvite precipitation capacity in the biofouling on the membrane surface and showed that heterotrophic bacteria with the ability to precipitate calcium carbonate and struvite constituted ~7.5% of the total platable bacteria. These belonged to the genera Lysinibacillus, Trichococcus, Comamomas and Bacillus. Pyrosequencing analysis of the microbial communities in the suspended cells and membrane biofouling showed a high degree of similarity in all the samples collected with respect to bacterial assemblage. The study of operational taxonomic units (OTUs) identified through pyrosequencing suggested that ~21% of the total bacterial community identified in the biofouling could potentially form calcium carbonate or struvite crystals in the pure MBBR-MBR system used for the treatment of urban wastewater. PMID:26000766

  17. Carbonate-cemented hardgrounds: a subtle indicator for seep activity offshore Humboldt Bay

    NASA Astrophysics Data System (ADS)

    Shapiro, R. S.; Bazard, D.

    2007-12-01

    Active hydrocarbon seeps are common in the accretionary prism of the Cascadia subduction zone. In Humboldt County, California, the prism is exposed at the surface as a series of fault-propagated anticlines trending NW-SE. Offshore of the town of Samoa, a northwest-plunging anticline is breached at approximately 40 meters water depth, allowing hydrocarbons to seep out to the seafloor (40.8° N, 124.25° W). The assumed microbial activity at the seep leads to the production of interstitial carbonate cements forming hardgrounds. Cementation is pervasive and blocks eroded from the seep area of the seabed are transported onshore during storm events. Blocks collected from the beach range from 3--40 centimeters across. The sediments of the blocks are palimpsest transgressive deposits composed mostly of immature fine sand, but ranging from very fine to rounded gravels 4 cm diameter. Cementation is not dependent on grain size as all of the sediment sizes are cemented. In rare void spaces, a concentric banding of cements is obvious. The interstitial cements preserve original sedimentary structures including graded beds and high-angle cross-beds. Centimeter-scale subspherical concretions occur on the undersides of some blocks. There is no disruption of bedding in contrast to other seeps where the expulsion of gas can create pockmarks, brecciation, and other disturbances. Unlike the better studied seeps farther south in the Eel River basin, the Samoa seeps do not seem to host a rich chemosynthetic fauna. Whole and (mostly) fragmented shells preserved by the cemented sands represent a typical benthic inner shelf community including Dendraster, Macoma, and Olivella. Burrows preserved in the sands are largely horizontal and 1--2 mm diameter. Seep carbonate-cemented hardgrounds are less well studied then the more obvious meter-scale 'chemoherm' deposits. However, they may be more prevalent in the rock record and provide a new proxy for locating ancient seeps and hydrocarbon

  18. Geochemical investigation of the potential for mobilizing non-methane hydrocarbons during carbon dioxide storage in deep coal beds

    USGS Publications Warehouse

    Kolak, J.J.; Burruss, R.C.

    2006-01-01

    Coal samples of different rank (lignite to anthracite) were extracted in the laboratory with supercritical CO2 (40 ??C; 10 MPa) to evaluate the potential for mobilizing non-methane hydrocarbons during CO2 storage (sequestration) or enhanced coal bed methane recovery from deep (???1-km depth) coal beds. The total measured alkane concentrations mobilized from the coal samples ranged from 3.0 to 64 g tonne-1 of dry coal. The highest alkane concentration was measured in the lignite sample extract; the lowest was measured in the anthracite sample extract. Substantial concentrations of polycyclic aromatic hydrocarbons (PAHs) were also mobilized from these samples: 3.1 - 91 g tonne-1 of dry coal. The greatest amounts of PAHs were mobilized from the high-volatile bituminous coal samples. The distributions of aliphatic and aromatic hydrocarbons mobilized from the coal samples also varied with rank. In general, these variations mimicked the chemical changes that occur with increasing degrees of coalification and thermal maturation. For example, the amount of PAHs mobilized from coal samples paralleled the general trend of bitumen formation with increasing coal rank. The coal samples yielded hydrocarbons during consecutive extractions with supercritical CO2, although the amount of hydrocarbons mobilized declined with each successive extraction. These results demonstrate that the potential for supercritical CO2 to mobilize non-methane hydrocarbons from coal beds, and the effect of coal rank on this process, are important to consider when evaluating deep coal beds for CO2 storage.

  19. Selecting activated carbon for water and wastewater treatability studies

    SciTech Connect

    Zhang, W.; Chang, Q.G.; Liu, W.D.; Li, B.J.; Jiang, W.X.; Fu, L.J.; Ying, W.C.

    2007-10-15

    A series of follow-up investigations were performed to produce data for improving the four-indicator carbon selection method that we developed to identify high-potential activated carbons effective for removing specific organic water pollutants. The carbon's pore structure and surface chemistry are dependent on the raw material and the activation process. Coconut carbons have relatively more small pores than large pores; coal and apricot nutshell/walnut shell fruit carbons have the desirable pore structures for removing adsorbates of all sizes. Chemical activation, excessive activation, and/or thermal reactivation enlarge small pores, resulting in reduced phenol number and higher tannic acid number. Activated carbon's phenol, iodine, methylene blue, and tannic acid numbers are convenient indicators of its surface area and pore volume of pore diameters < 10, 10-15, 15-28, and > 28 angstrom, respectively. The phenol number of a carbon is also a good indicator of its surface acidity of oxygen-containing organic functional groups that affect the adsorptive capacity for aromatic and other small polar organics. The tannic acid number is an indicator of carbon's capacity for large, high-molecular-weight natural organic precursors of disinfection by-products in water treatment. The experimental results for removing nitrobenzene, methyl-tert-butyl ether, 4,4-bisphenol, humic acid, and the organic constituents of a biologically treated coking-plant effluent have demonstrated the effectiveness of this capacity-indicator-based method of carbon selection.

  20. Effect of nutrient enrichment on the source and composition of sediment organic carbon in tropical seagrass beds in the South China Sea.

    PubMed

    Liu, Songlin; Jiang, Zhijian; Zhang, Jingping; Wu, Yunchao; Lian, Zhonglian; Huang, Xiaoping

    2016-09-15

    To assess the effect of nutrient enrichment on the source and composition of sediment organic carbon (SOC) beneath Thalassia hemprichii and Enhalus acoroides in tropical seagrass beds, Xincun Bay, South China Sea, intertidal sediment, primary producers, and seawater samples were collected. No significant differences on sediment δ(13)C, SOC, and microbial biomass carbon (MBC) were observed between T. hemprichii and E. acoroides. SOC was mainly of autochthonous origin, while the contribution of seagrass to SOC was less than that of suspended particulate organic matter, macroalgae and epiphytes. High nutrient concentrations contributed substantially to SOC of seagrass, macroalgae, and epiphytes. The SOC, MBC, and MBC/SOC ratio in the nearest transect to fish farming were the highest. This suggested a more labile composition of SOC and shorter turnover times in higher nutrient regions. Therefore, the research indicates that nutrient enrichment could enhance plant-derived contributions to SOC and microbial use efficiency. PMID:27334726

  1. Effect of nutrient enrichment on the source and composition of sediment organic carbon in tropical seagrass beds in the South China Sea.

    PubMed

    Liu, Songlin; Jiang, Zhijian; Zhang, Jingping; Wu, Yunchao; Lian, Zhonglian; Huang, Xiaoping

    2016-09-15

    To assess the effect of nutrient enrichment on the source and composition of sediment organic carbon (SOC) beneath Thalassia hemprichii and Enhalus acoroides in tropical seagrass beds, Xincun Bay, South China Sea, intertidal sediment, primary producers, and seawater samples were collected. No significant differences on sediment δ(13)C, SOC, and microbial biomass carbon (MBC) were observed between T. hemprichii and E. acoroides. SOC was mainly of autochthonous origin, while the contribution of seagrass to SOC was less than that of suspended particulate organic matter, macroalgae and epiphytes. High nutrient concentrations contributed substantially to SOC of seagrass, macroalgae, and epiphytes. The SOC, MBC, and MBC/SOC ratio in the nearest transect to fish farming were the highest. This suggested a more labile composition of SOC and shorter turnover times in higher nutrient regions. Therefore, the research indicates that nutrient enrichment could enhance plant-derived contributions to SOC and microbial use efficiency.

  2. An extended equation for rate coefficients for adsorption of organic vapors and gases on activated carbons in air-purifying respirator cartridges.

    PubMed

    Wood, G O; Lodewyckx, P

    2003-01-01

    Organic vapor adsorption rates in air-purifying respirator cartridges (and other packed beds of activated carbon granules) need to be known for estimating service lives. The correlation of Lodewyckx and Vansant [AIHAJ 61:501-505 (2000)] for mass transfer coefficients for organic vapor adsorption onto activated carbon was tested with additional data from three sources. It was then extended to better describe all the data, including that for gases. The additional parameter that accomplished this was the square root of molar equilibrium capacity of the vapor or gas on the carbon. This change, along with skew corrections when appropriate, resulted in better correlations with all experimental rate coefficients. PMID:14521430

  3. Control of acid gases using a fluidized bed adsorber.

    PubMed

    Chiang, Bo-Chin; Wey, Ming-Yen; Yeh, Chia-Lin

    2003-08-01

    During incineration, secondary pollutants such as acid gases, organic compounds, heavy metals and particulates are generated. Among these pollutants, the acid gases, including sulfur oxides (SO(x)) and hydrogen chloride (HCl), can cause corrosion of the incinerator piping and can generate acid rain after being emitted to the atmosphere. To address this problem, the present study used a novel combination of air pollution control devices (APCDs), composed of a fluidized bed adsorber integrated with a fabric filter. The major objective of the work is to demonstrate the performance of a fluidized bed adsorber for removal of acid gases from flue gas of an incinerator. The adsorbents added in the fluidized bed adsorber were mainly granular activated carbon (AC; with or without chemical treatment) and with calcium oxide used as an additive. The advantages of a fluidized bed reactor for high mass transfer and high gas-solid contact can enhance the removal of acid gases when using a dry method. On the other hand, because the fluidized bed can filter particles, fine particles prior to and after passing through the fluidized bed adsorber were investigated. The competing adsorption on activated carbon between different characteristics of pollutants was also given preliminary discussion. The results indicate that the removal efficiencies of the investigated acid gases, SO(2) and HCl, are higher than 94 and 87%, respectively. Thus, a fluidized bed adsorber integrated with a fabric filter has the potential to replace conventional APCDs, even when there are other pollutants at the same time.

  4. 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.

  5. Removal potential of toxic 2378-substituted PCDD/F from incinerator flue gases by waste-derived activated carbons

    SciTech Connect

    Hajizadeh, Yaghoub; Onwudili, Jude A.; Williams, Paul T.

    2011-06-15

    The application of activated carbons has become a commonly used emission control protocol for the removal or adsorption of persistent organic pollutants from the flue gas streams of waste incinerators. In this study, the 2378-substituted PCDD/F removal efficiency of three types of activated carbons derived from the pyrolysis of refuse derived fuel, textile waste and scrap tyre was investigated and compared with that of a commercial carbon. Experiments were carried out in a laboratory scale fixed-bed reactor under a simulated flue gas at 275 deg. C with a reaction period of four days. The PCDD/F in the solid matrices and exhaust gas, were analyzed using gas chromatography coupled with a triple quadrupole mass spectrometer. In the absence of activated carbon adsorbent, there was a significant increase in the concentration of toxic PCDD/F produced in the reacted flyash, reaching up to 6.6 times higher than in the raw flyash. In addition, there was a substantial release of PCDD/F into the gas phase, which was found in the flue gas trapping system. By application of the different commercial, refuse derived fuel, textile and tyre activated carbons the total PCDD/F toxic equivalent removal efficiencies in the exhaust gas stream were 58%, 57%, 64% and 52%, respectively. In general, the removal of the PCDDs was much higher with an average of 85% compared to PCDFs at 41%. Analysis of the reacted activated carbons showed that there was some formation of PCDD/F, for instance, a total of 60.6 {mu}g I-TEQ kg{sup -1} toxic PCDD/F was formed in the refuse derived fuel activated carbon compared to 34 {mu}g I-TEQ kg{sup -1} in the commercial activated carbon. The activated carbons derived from the pyrolysis of waste, therefore, showed good potential as a control material for PCDD/F emissions in waste incinerator flue gases.

  6. Grain-based activated carbons for natural gas storage.

    PubMed

    Zhang, Tengyan; Walawender, Walter P; Fan, L T

    2010-03-01

    Natural gas has emerged as a potential alternative to gasoline due to the increase in global energy demand and environmental concerns. An investigation was undertaken to explore the technical feasibility of implementing the adsorbed natural gas (ANG) storage in the fuel tanks of motor vehicles with activated carbons from biomass, e.g., sorghum and wheat. The grain-based activated carbons were prepared by chemical activation; the experimental parameters were varied to identify the optimum conditions. The porosity of the resultant activated carbons was evaluated through nitrogen adsorption; and the storage capacity, through methane adsorption. A comparative study was also carried out with commercial activated carbons from charcoal. The highest storage factor attained was 89 for compacted grain-based activated carbons from grain sorghum with a bulk density of 0.65 g/cm(3), and the highest storage factor attained is 106 for compacted commercial activated carbons (Calgon) with a bulk density of 0.70 g/cm(3). The storage factor was found to increase approximately linearly with increasing bulk density and to be independent of the extent of compaction. This implies that the grain-based activated carbons are the ideal candidates for the ANG storage.

  7. CCN activation of pure and coated carbon black particles.

    PubMed

    Dusek, U; Reischl, G P; Hitzenberger, R

    2006-02-15

    The CCN (cloud condensation nucleus) activation of pure and coated carbon black particles was investigated using the University of Vienna cloud condensation nuclei counter (Giebl, H.; Berner, A.; Reischl, G.; Puxbaum, H.; Kasper-Giebl, A.; Hitzenberger, R. J. Aerosol Sci. 2002, 33, 1623-1634). The particles were produced by nebulizing an aqueous suspension of carbon black in a Collison atomizer. The activation of pure carbon black particles was found to require higher supersaturations than predicted by calculations representing the particles as insoluble, wettable spheres with mobility equivalent diameter. To test whether this effect is an artifact due to heating of the light-absorbing carbon black particles in the laser beam, experiments at different laser powers were conducted. No systematic dependence of the activation of pure carbon black particles on laser power was observed. The observations could be modeled using spherical particles and an effective contact angle of 4-6 degrees of water at their surface. The addition of a small amount of NaCl to the carbon black particles (by adding 5% by mass NaCl to the carbon black suspension) greatly enhanced their CCN efficiency. The measured CCN efficiencies were consistent with Kohler theory for particles consisting of insoluble and hygroscopic material. However, coating the carbon black particles with hexadecanol (a typical film-forming compound with one hydrophobic and one hydrophilic end) efficiently suppressed the CCN activation of the carbon black particles.

  8. Soil Inorganic Carbon in Deserts: Active Carbon Sink or Inert Reservoir?

    NASA Astrophysics Data System (ADS)

    Monger, H. C.; Cole, D. R.

    2011-12-01

    Soil inorganic carbon is the third largest C pool in the active global carbon cycle, containing at least 800 petagrams of carbon. Although carbonate dissolution-precipitation reactions have been understood for over a century, the role of soil inorganic carbon in carbon sequestration, and in particular pedogenic carbonate, is a deceptively complex process because it involves interdependent connections among climate, plants, microorganisms, silicate minerals, soil moisture, pH, and Ca supply via rain, dust, or in situ weathering. An understanding of soil inorganic carbon as a sink or reservoir also requires examination of the system at local to continental scales and at seasonal to millennial time scales. In desert soils studied in North America, carbon isotope ratios and radiocarbon dates were measured in combination with electron microscopy, lab and field experiments with biological calcite formation, and field measurements of carbon dioxide emissions. These investigations reveal that soil inorganic carbon is both an active sink and a inert reservoir depending on the spatial and temporal scale and source of calcium.

  9. Economical and ecological comparison of granular activated carbon (GAC) adsorber refill strategies.

    PubMed

    Bayer, Peter; Heuer, Edda; Karl, Ute; Finkel, Michael

    2005-05-01

    Technical constraints can leave a considerable freedom in the design of a technology, production or service strategy. Choosing between economical or ecological decision criteria then characteristically leads to controversial solutions of ideal systems. For the adaptation of granular-activated carbon (GAC) fixed beds, various technical factors determine the adsorber volume required to achieve a desired service life. In considering carbon replacement and recycling, a variety of refill strategies are available that differ in terms of refill interval, respective adsorber volume, and time-dependent use of virgin, as well as recycled GAC. Focusing on the treatment of contaminant groundwater, we compare cost-optimal reactor configurations and refill strategies to the ecologically best alternatives. Costs and consumption of GAC are quantified within a technical-economical framework. The emissions from GAC production out of hard coal, transport and recycling are equally derived through a life cycle impact assessment. It is shown how high discount rates lead to a preference of small fixed-bed volumes, and accordingly, a high number of refills. For fixed discount rates, the investigation reveals that both the economical as well as ecological assessment of refill strategies are especially sensitive to the relative valuation of virgin and recycled GAC. Since recycling results in economic and ecological benefits, optimized systems thus may differ only slightly.

  10. Effectiveness of a Sugar-Yeast Monitor and a Chemical Lure for Detecting Bed Bugs.

    PubMed

    Singh, Narinderpal; Wang, Changlu; Cooper, Richard

    2015-06-01

    Effective bed bug (Cimex lectularius L.) monitors have been actively sought in the past few years to help detect bed bugs and measure the effectiveness of treatments. Most of the available active monitors are either expensive or ineffective. We designed a simple and affordable active bed bug monitor that uses sugar-yeast fermentation and an experimental chemical lure to detect bed bugs. The sugar-yeast mixture released carbon dioxide at a similar rate (average 405.1 ml/min) as dry ice (average 397.0 ml/min) during the first 8 h after activation. In naturally infested apartments, the sugar-yeast monitor containing an experimental chemical lure (nonanal, L-lactic acid, 1-octen-3-ol, and spearmint oil) was equally effective as the dry ice monitor containing the same lure in trapping bed bugs. Placing one sugar-yeast monitor per apartment for 1-d was equally effective as 11-d placement of 6-18 Climbup insect interceptors (a commonly used bed bug monitor) under furniture legs for trapping bed bugs. When carbon dioxide was present, pair-wise comparisons showed the experimental lure increased trap catch by 7.2 times. This sugar-yeast monitor with a chemical lure is an affordable and effective tool for monitoring bed bugs. This monitor is especially useful for monitoring bed bugs where a human host is not present. PMID:26470258

  11. Effectiveness of a Sugar-Yeast Monitor and a Chemical Lure for Detecting Bed Bugs.

    PubMed

    Singh, Narinderpal; Wang, Changlu; Cooper, Richard

    2015-06-01

    Effective bed bug (Cimex lectularius L.) monitors have been actively sought in the past few years to help detect bed bugs and measure the effectiveness of treatments. Most of the available active monitors are either expensive or ineffective. We designed a simple and affordable active bed bug monitor that uses sugar-yeast fermentation and an experimental chemical lure to detect bed bugs. The sugar-yeast mixture released carbon dioxide at a similar rate (average 405.1 ml/min) as dry ice (average 397.0 ml/min) during the first 8 h after activation. In naturally infested apartments, the sugar-yeast monitor containing an experimental chemical lure (nonanal, L-lactic acid, 1-octen-3-ol, and spearmint oil) was equally effective as the dry ice monitor containing the same lure in trapping bed bugs. Placing one sugar-yeast monitor per apartment for 1-d was equally effective as 11-d placement of 6-18 Climbup insect interceptors (a commonly used bed bug monitor) under furniture legs for trapping bed bugs. When carbon dioxide was present, pair-wise comparisons showed the experimental lure increased trap catch by 7.2 times. This sugar-yeast monitor with a chemical lure is an affordable and effective tool for monitoring bed bugs. This monitor is especially useful for monitoring bed bugs where a human host is not present.

  12. Breakthrough curves for toluene adsorption on different types of activated carbon fibers: application in respiratory protection.

    PubMed

    Balanay, Jo Anne G; Floyd, Evan L; Lungu, Claudiu T

    2015-05-01

    Activated carbon fibers (ACF) are considered viable alternative adsorbent materials in respirators because of their larger surface area, lighter weight, and fabric form. The purpose of this study was to characterize the breakthrough curves of toluene for different types of commercially available ACFs to understand their potential service lives in respirators. Two forms of ACF, cloth (AC) and felt (AF), with three surface areas each were tested. ACFs were challenged with six toluene concentrations (50-500 p.p.m.) at constant air temperature (23°C), relative humidity (50%), and air flow (16 l min-1) at different bed depths. Breakthrough data were obtained using continuous monitoring by gas chromatography using a gas sampling valve. The ACF specific surface areas were measured by an automatic physisorption analyzer. Results showed unique shapes of breakthrough curves for each ACF form: AC demonstrated a gradual increase in breakthrough concentration, whereas AF showed abrupt increase in concentration from the breakpoint, which was attributed to the difference in fiber density between the forms. AF has steeper breakthrough curves compared with AC with similar specific surface area. AC exhibits higher 10% breakthrough times for a given bed depth due to higher mass per bed depth compared with AF, indicating more adsorption per bed depth with AC. ACF in respirators may be appropriate for use as protection in environments with toluene concentration at the Occupational Safety and Health Administration Permissible Exposure Limit, or during emergency escape for higher toluene concentrations. ACF has shown great potential for application in respiratory protection against toluene and in the development of thinner, lighter, and more efficient respirators. PMID:25528579

  13. Breakthrough curves for toluene adsorption on different types of activated carbon fibers: application in respiratory protection.

    PubMed

    Balanay, Jo Anne G; Floyd, Evan L; Lungu, Claudiu T

    2015-05-01

    Activated carbon fibers (ACF) are considered viable alternative adsorbent materials in respirators because of their larger surface area, lighter weight, and fabric form. The purpose of this study was to characterize the breakthrough curves of toluene for different types of commercially available ACFs to understand their potential service lives in respirators. Two forms of ACF, cloth (AC) and felt (AF), with three surface areas each were tested. ACFs were challenged with six toluene concentrations (50-500 p.p.m.) at constant air temperature (23°C), relative humidity (50%), and air flow (16 l min-1) at different bed depths. Breakthrough data were obtained using continuous monitoring by gas chromatography using a gas sampling valve. The ACF specific surface areas were measured by an automatic physisorption analyzer. Results showed unique shapes of breakthrough curves for each ACF form: AC demonstrated a gradual increase in breakthrough concentration, whereas AF showed abrupt increase in concentration from the breakpoint, which was attributed to the difference in fiber density between the forms. AF has steeper breakthrough curves compared with AC with similar specific surface area. AC exhibits higher 10% breakthrough times for a given bed depth due to higher mass per bed depth compared with AF, indicating more adsorption per bed depth with AC. ACF in respirators may be appropriate for use as protection in environments with toluene concentration at the Occupational Safety and Health Administration Permissible Exposure Limit, or during emergency escape for higher toluene concentrations. ACF has shown great potential for application in respiratory protection against toluene and in the development of thinner, lighter, and more efficient respirators.

  14. Ocean bottom sediments as an active carbon pool.

    NASA Astrophysics Data System (ADS)

    Zimov, N.; Zimov, S. A.

    2015-12-01

    Bottom deposits of oceans, seas and lakes are long term carbon sinks - particulate organic carbon falls to the bottom where it is covered by sediments and preserved by anoxic conditions. However, the upper horizons of these deep sediments ('active layer') interact with bottom waters through diffusion, bubbling of gasses and bioturbation and can thus also act as temporary carbon sources given favorable environment conditions. Oxygen diffusion is the main factor that limits organic decomposition in bottom deposits. Depth of diffusion depends on porosity of sediments and rates of oxygen consumption in the upper horizons. Amplified organic rain leads to higher oxygen demand and, consequently, to a thinner oxic horizon in the bottom sediments. Declined ocean productivity, in contrast, allows oxygen to diffuse deeper into the bottom sediments and remobilizes previously preserved carbon. Therefore a substantial decline in ocean productivity during glacial periods could cause ocean sediments to shift abruptly from a carbon sink to a considerable carbon source. To estimate the effects of the phenomena described above, we present a model of the dynamics and vertical distribution of organic carbon in ocean sediments that considers the input of organic rain, sediments porosity, oxygen availability, rates of sedimentation to the ocean floor and bioturbation. The model enables quantification of bulk carbon storage, carbon distribution within the 'active layer', and the flux of carbon from the upper sediment horizons to deeper deposits as sediments accumulate on the ocean floor. Applying our model, we find that during glacial periods, decreased ocean productivity led to the mobilization of old carbon previously stored within anoxic horizons. Under this scenario, carbon transfer from sediments to ocean waters would have exceeded 10 kg/m2. Our study therefore, suggests that the ocean floor is not merely a passive buffer in the global carbon cycle, but instead an active pool which

  15. Liquid-phase adsorption of organic compounds by granular activated carbon and activated carbon fibers

    SciTech Connect

    Lin, S.H.; Hsu, F.M.

    1995-06-01

    Liquid-phase adsorption of organic compounds by granular activated carbon (GAC) and activated carbon fibers (ACFs) is investigated. Acetone, isopropyl alcohol (IPA), phenol, and tetrahydrofuran (THF) were employed as the model compounds for the present study. It is observed from the experimental results that adsorption of organic compounds by GAC and ACF is influenced by the BET (Brunauer-Emmett-Teller) surface area of adsorbent and the molecular weight, polarity, and solubility of the adsorbate. The adsorption characteristics of GAC and ACFs were found to differ rather significantly. In terms of the adsorption capacity of organic compounds, the time to reach equilibrium adsorption, and the time for complete desorption, ACFs have been observed to be considerably better than GAC. For the organic compounds tested here, the GAC adsorptions were shown to be represented well by the Langmuir isotherm while the ACF adsorption could be adequately described by the Langmuir or the Freundlich isotherm. Column adsorption tests indicated that the exhausted ACFs can be effectively regenerated by static in situ thermal desorption at 150 C, but the same regeneration conditions do not do as well for the exhausted GAC.

  16. Activation of peroxymonosulfate by graphitic carbon nitride loaded on activated carbon for organic pollutants degradation.

    PubMed

    Wei, Mingyu; Gao, Long; Li, Jun; Fang, Jia; Cai, Wenxuan; Li, Xiaoxia; Xu, Aihua

    2016-10-01

    Graphitic carbon nitride supported on activated carbon (g-C3N4/AC) was prepared through an in situ thermal approach and used as a metal free catalyst for pollutants degradation in the presence of peroxymonosulfate (PMS) without light irradiation. It was found that g-C3N4 was highly dispersed on the surface of AC with the increase of surface area and the exposition of more edges and defects. The much easier oxidation of C species in g-C3N4 to CO was also observed from XPS spectra. Acid Orange 7 (AO7) and other organic pollutants could be completely degraded by the g-C3N4/AC catalyst within 20min with PMS, while g-C3N4+PMS and AC+PMS showed no significant activity for the reaction. The performance of the catalyst was significantly influenced by the amount of g-C3N4 loaded on AC; but was nearly not affected by the initial solution pH and reaction temperature. In addition, the catalysts presented good stability. A nonradical mechanism accompanied by radical generation (HO and SO4(-)) in AO7 oxidation was proposed in the system. The CO groups play a key role in the process; while the exposure of more N-(C)3 group can further increase its electron density and basicity. This study can contribute to the development of green materials for sustainable remediation of aqueous organic pollutants. PMID:27214000

  17. Activation of peroxymonosulfate by graphitic carbon nitride loaded on activated carbon for organic pollutants degradation.

    PubMed

    Wei, Mingyu; Gao, Long; Li, Jun; Fang, Jia; Cai, Wenxuan; Li, Xiaoxia; Xu, Aihua

    2016-10-01

    Graphitic carbon nitride supported on activated carbon (g-C3N4/AC) was prepared through an in situ thermal approach and used as a metal free catalyst for pollutants degradation in the presence of peroxymonosulfate (PMS) without light irradiation. It was found that g-C3N4 was highly dispersed on the surface of AC with the increase of surface area and the exposition of more edges and defects. The much easier oxidation of C species in g-C3N4 to CO was also observed from XPS spectra. Acid Orange 7 (AO7) and other organic pollutants could be completely degraded by the g-C3N4/AC catalyst within 20min with PMS, while g-C3N4+PMS and AC+PMS showed no significant activity for the reaction. The performance of the catalyst was significantly influenced by the amount of g-C3N4 loaded on AC; but was nearly not affected by the initial solution pH and reaction temperature. In addition, the catalysts presented good stability. A nonradical mechanism accompanied by radical generation (HO and SO4(-)) in AO7 oxidation was proposed in the system. The CO groups play a key role in the process; while the exposure of more N-(C)3 group can further increase its electron density and basicity. This study can contribute to the development of green materials for sustainable remediation of aqueous organic pollutants.

  18. Physicochemical and porosity characteristics of thermally regenerated activated carbon polluted with biological activated carbon process.

    PubMed

    Dong, Lihua; Liu, Wenjun; Jiang, Renfu; Wang, Zhansheng

    2014-11-01

    The characteristics of thermally regenerated activated carbon (AC) polluted with biological activated carbon (BAC) process were investigated. The results showed that the true micropore and sub-micropore volume, pH value, bulk density, and hardness of regenerated AC decreased compared to the virgin AC, but the total pore volume increased. XPS analysis displayed that the ash contents of Al, Si, and Ca in the regenerated AC respectively increased by 3.83%, 2.62% and 1.8%. FTIR spectrum showed that the surface functional groups of virgin and regenerated AC did not change significantly. Pore size distributions indicated that the AC regeneration process resulted in the decrease of micropore and macropore (D>10 μm) volume and the increase of mesopore and macropore (0.1 μm

  19. 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.

  20. 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.

  1. Nickel adsorption by sodium polyacrylate-grafted activated carbon.

    PubMed

    Ewecharoen, A; Thiravetyan, P; Wendel, E; Bertagnolli, H

    2009-11-15

    A novel sodium polyacrylate grafted activated carbon was produced by using gamma radiation to increase the number of functional groups on the surface. After irradiation the capacity for nickel adsorption was studied and found to have increased from 44.1 to 55.7 mg g(-1). X-ray absorption spectroscopy showed that the adsorbed nickel on activated carbon and irradiation-grafted activated carbon was coordinated with 6 oxygen atoms at 2.04-2.06 A. It is proposed that this grafting technique could be applied to other adsorbents to increase the efficiency of metal adsorption.

  2. 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.

  3. Tapered bed bioreactor

    DOEpatents

    Scott, Charles D.; Hancher, Charles W.

    1977-01-01

    A vertically oriented conically shaped column is used as a fluidized bed bioreactor wherein biologically catalyzed reactions are conducted in a continuous manner. The column utilizes a packing material a support having attached thereto a biologically active catalytic material.

  4. Physical and electrochemical study of halide-modified activated carbons

    NASA Astrophysics Data System (ADS)

    Barpanda, Prabeer

    The current thesis aims to improve the electrochemical capacity of activated carbon electrodes, which enjoy prominent position in commercial electrochemical capacitors. Our approach was to develop electrochemical capacity by developing faradaic pseudocapacitance in carbon through a novel mechanochemical modification using iodine and bromine. Various commercial carbons were mechanochemically modified via solid-state iodation and vapour phase iodine-incorporation. The halidation-induced changes in the structure, composition, morphology, electrical and electrochemical properties of carbon materials were studied using different characterization techniques encompassing XRD, XRF, XPS, Raman spectroscopy, BET study, TEM, SAXS and electrochemical testing followed by an intensive battery of physical and electrochemical characterization. The introduction of iodine into carbon system led to the formation of polyiodide species that were preferentially reacted within the micropore voids within the carbon leading to the development of a faradaic reaction at 3.1V. In spite of the lower surface area of modified carbon, we observed manyfold increase in its electrochemical capacity. Parallel inception of non-faradaic development and faradaic pseudocapacitive reaction led to promising gravimetric, surface area normalized and volumetric capacity in iodated carbons. With promising electrochemical improvement post halidation process, the chemical halidation method was extended to different class of carbons and halides. Carbons ranging from amorphous (activated) carbons to crystalline carbons (graphites, fluorographites) were iodine-modified to gain further insight on the local graphite-iodine chemical interaction. In addition, the effect of pore size distribution on chemical iodation process was studied by using in-house fabricated microporous carbon. A comparative study of commercial mesoporous carbons and in-house fabricated microporous carbons showed higher iodine-uptake ability and

  5. Hydrogen storage on activated carbon. Final report

    SciTech Connect

    Schwarz, J.A.

    1994-11-01

    The project studied factors that influence the ability of carbon to store hydrogen and developed techniques to enhance that ability in naturally occurring and factory-produced commercial carbon materials. During testing of enhanced materials, levels of hydrogen storage were achieved that compare well with conventional forms of energy storage, including lead-acid batteries, gasoline, and diesel fuel. Using the best materials, an electric car with a modern fuel cell to convert the hydrogen directly to electricity would have a range of over 1,000 miles. This assumes that the total allowable weight of the fuel cell and carbon/hydrogen storage system is no greater than the present weight of batteries in an existing electric vehicle. By comparison, gasoline cars generally are limited to about a 450-mile range, and battery-electric cars to 40 to 60 miles. The project also developed a new class of carbon materials, based on polymers and other organic compounds, in which the best hydrogen-storing factors discovered earlier were {open_quotes}molecularly engineered{close_quotes} into the new materials. It is believed that these new molecularly engineered materials are likely to exceed the performance of the naturally occurring and manufactured carbons seen earlier with respect to hydrogen storage.

  6. Production and characterization of activated carbons from cereal grains

    SciTech Connect

    Venkatraman, A.; Walawender, W.P.; Fan, L.T.

    1996-12-31

    The term, activated carbon, is a generic name for a family of carbonaceous materials with well-developed porosities and consequently, large adsorptive capacities. Activated carbons are increasingly being consumed worldwide for environmental applications such as separation of volatiles from bulk gases and purification of water and waste-water streams. The global annual production is estimated to be around 300 million kilograms, with a rate of increase of 7% each year. Activated carbons can be prepared from a variety of raw materials. Approximately, 60% of the activated carbons generated in the United States is produced from coal; 20%, from coconut shells; and the remaining 20% from wood and other sources of biomass. The pore structure and properties of activated carbons are influenced by the nature of the starting material and the initial physical and chemical conditioning as well as the process conditions involved in its manufacture. The porous structures of charcoals and activated carbons obtained by the carbonization of kernels have been characterized.

  7. Microstructure and surface properties of lignocellulosic-based activated carbons

    NASA Astrophysics Data System (ADS)

    González-García, P.; Centeno, T. A.; Urones-Garrote, E.; Ávila-Brande, D.; Otero-Díaz, L. C.

    2013-01-01

    Low cost activated carbons have been produced via chemical activation, by using KOH at 700 °C, from the bamboo species Guadua Angustifolia and Bambusa Vulgaris Striata and the residues from shells of the fruits of Castanea Sativa and Juglans Regia as carbon precursors. The scanning electron microscopy micrographs show the conservation of the precursor shape in the case of the Guadua Angustifolia and Bambusa Vulgaris Striata activated carbons. Transmission electron microscopy analyses reveal that these materials consist of carbon platelet-like particles with variable length and thickness, formed by highly disordered graphene-like layers with sp2 content ≈ 95% and average mass density of 1.65 g/cm3 (25% below standard graphite). Textural parameters indicate a high porosity development with surface areas ranging from 850 to 1100 m2/g and average pore width centered in the supermicropores range (1.3-1.8 nm). The electrochemical performance of the activated carbons shows specific capacitance values at low current density (1 mA/cm2) as high as 161 F/g in the Juglans Regia activated carbon, as a result of its textural parameters and the presence of pseudocapacitance derived from surface oxygenated acidic groups (mainly quinones and ethers) identified in this activated carbon.

  8. Adsorption of selected pharmaceuticals and an endocrine disrupting compound by granular activated carbon. 2. Model prediction

    SciTech Connect

    Yu, Z.; Peldszus, S.; Huck, P.M.

    2009-03-01

    The adsorption of two representative pharmaceutically active compounds (PhACs) naproxen and carbamazepine and one endocrine disrupting compound (EDC) nonylphenol was studied in pilot-scale granular activated carbon (GAC) adsorbers using post-sedimentation (PS) water from a full-scale drinking water treatment plant. The GAC adsorbents were coal-based Calgon Filtrasorb 400 and coconut shell-based PICA CTIF TE. Acidic naproxen broke through fastest while nonylphenol was removed best, which was consistent with the degree to which fouling affected compound removals. Model predictions and experimental data were generally in good agreement for all three compounds, which demonstrated the effectiveness and robustness of the pore and surface diffusion model (PSDM) used in combination with the time-variable parameter approach for predicting removals at environmentally relevant concentrations (i.e., ng/L range). Sensitivity analyses suggested that accurate determination of film diffusion coefficients was critical for predicting breakthrough for naproxen and carbamazepine, in particular when high removals are targeted. Model simulations demonstrated that GAC carbon usage rates (CURs) for naproxen were substantially influenced by the empty bed contact time (EBCT) at the investigated conditions. Model-based comparisons between GAC CURs and minimum CURs for powdered activated carbon (PAC) applications suggested that PAC would be most appropriate for achieving 90% removal of naproxen, whereas GAC would be more suitable for nonylphenol. 25 refs., 4 figs., 1 tab.

  9. Adsorption of selected pharmaceuticals and an endocrine disrupting compound by granular activated carbon. 2. Model prediction.

    PubMed

    Yu, Zirui; Peldszus, Sigrid; Huck, Peter M

    2009-03-01

    The adsorption of two representative pharmaceutically active compounds (PhACs)-naproxen and carbamazepine and one endocrine disrupting compound (EDC)-nonylphenol was studied in pilot-scale granular activated carbon (GAC) adsorbers using post-sedimentation (PS) water from a full-scale drinking water treatment plant. Acidic naproxen broke through fastest while nonylphenol was removed best, which was consistent with the degree to which fouling affected compound removals. Model predictions and experimental data were generally in good agreement for all three compounds, which demonstrated the effectiveness and robustness of the pore and surface diffusion model (PSDM) used in combination with the time-variable parameter approach for predicting removals at environmentally relevant concentrations (i.e., ng/L range). Sensitivity analyses suggested that accurate determination of film diffusion coefficients was critical for predicting breakthrough for naproxen and carbamazepine, in particular when high removals are targeted. Model simulations demonstrated that GAC carbon usage rates (CURs) for naproxen were substantially influenced by the empty bed contact time (EBCT) at the investigated conditions. Model-based comparisons between GAC CURs and minimum CURs for powdered activated carbon (PAC) applications suggested that PAC would be most appropriate for achieving 90% removal of naproxen, whereas GAC would be more suitable for nonylphenol. PMID:19350922

  10. Effect of Surface Characteristics of Wood-Based Activated Carbons on Adsorption of Hydrogen Sulfide.

    PubMed

    Adib; Bagreev; Bandosz

    1999-06-15

    Three wood-based commercial activated carbons supplied by Westvaco were studied as adsorbents of hydrogen sulfide. The initial materials were characterized using sorption of nitrogen, Boehm titration, potentiometric titration, water sorption, thermal analysis, and temperature-programmed desorption. The breakthrough tests were done at low concentrations of H2S in the input gas to simulate conditions in water pollution control plants where carbon beds are used as odor adsorbents. In spite of apparent general similarities in the origin of the materials, method of activation, surface chemistry, and porosity, significant differences in their performance as hydrogen sulfide adsorbents were observed. Results show that the combined effect of the presence of pores large enough to accommodate surface functional groups and small enough to have the film of water at relatively low pressure contributes to oxidation of hydrogen sulfide. Moreover, there are features of activated carbon surfaces such as local environment of acidic/basic groups along with the presence of alkali metals which are important to the oxidation process. Copyright 1999 Academic Press.

  11. CO(2) adsorption on supported molecular amidine systems on activated carbon.

    PubMed

    Alesi, W Richard; Gray, McMahan; Kitchin, John R

    2010-08-23

    The CO(2) capture capacities for typical flue gas capture and regeneration conditions of two tertiary amidine N-methyltetrahydropyrimidine (MTHP) derivatives supported on activated carbon were determined through temperature-controlled packed-bed reactor experiments. Adsorption-desorption experiments were conducted at initial adsorption temperatures ranging from 29 degrees C to 50 degrees C with temperature-programmed regeneration under an inert purge stream. In addition to the capture capacity of each amine, the efficiencies at which the amidines interact with CO(2) were determined. Capture capacities were obtained for 1,5-diazo-bicyclo[4.3.0]non-5-ene (DBN) and 1,8-diazobicyclo[5.4.0]-undec-7-ene (DBU) supported on activated carbon at a loading of approximately 2.7 mol amidine per kg of sorbent. Moisture was found to be essential for CO(2) capture on the amidines, but parasitic moisture sorption on the activated carbon ultimately limited the capture capacities. DBN was shown to have a higher capture capacity of 0.8 mol CO(2) per kg of sorbent and an efficiency of 0.30 mol CO(2) per mol of amidine at an adsorption temperature of 29 degrees C compared to DBU. The results of these experiments were then used in conjunction with a single-site adsorption model to derive the Gibbs free energy for the capture reaction, which can provide information about the suitability of the sorbent under different operating conditions. PMID:20730982

  12. Mechanism of phenol adsorption onto electro-activated carbon granules.

    PubMed

    Lounici, H; Aioueche, F; Belhocine, D; Drouiche, M; Pauss, A; Mameri, N

    2004-01-01

    The main purpose of this paper is to determine the mechanisms which govern the adsorption of the phenol onto electro-activated carbon granules. This new activation technique allowed an increase of the performance of the adsorbent. Two models were utilised to understand the improvement in the performance of electroactivated carbon granules. The first, a simple external resistance model based on film resistance, gave acceptable predictions, with an error of less than 15%, between the theoretical results and experimental data independent of the activation potential and phenol initial concentration. The second linear model, based on diffusion phenomena, was more representative in describing the experiment than the first model. It was observed that the electro-activation method did not change the mechanism which governs phenol adsorption onto granular carbon. Indeed, the same mathematical model based on diffusion phenomena made it possible to predict with a very low error (less than 5%) the experimental data obtained for the favourable activation potential, without activation potential and with an unfavourable activation potential. The electro-activation technique makes it possible to increase the number of active sites that improve the performance of the electro-activated granular carbon compared with conventional granular activated carbon.

  13. Production of Very Pure Hydrogen with Simultaneous Capture of Carbon Dioxide using the Redox Reactions of Iron Oxides in Packed Beds

    SciTech Connect

    Bohn, C.D.; Muller, C.R.; Cleeton, J.P.; Hayhurst, A.N.; Davidson,J.F.; Scott, S.A.; Dennis, J.S.

    2008-10-15

    A chemical looping process, which uses a packed bed of the various oxides of iron, has been formulated to produce separate, pure streams of H{sub 2} and CO{sub 2} from syngas. The process has the following stages: (1) Reduction of Fe{sub 2}O{sub 3} to Fe{sub 0.947}O in the syngas from gasifying coal or biomass. This stage generates pure CO{sub 2}, once the water has been condensed. (2) Subsequent oxidation of Fe{sub 0.947}O to Fe3O{sub 4} using stearn, to simultaneously produce H{sub 2}. (3) Further oxidation of Fe3O{sub 4} to Fe{sub 2}O{sub 3} using air to return the oxide to step 1. Step 1 was studied here using a Mixture of CO + CO{sub 2} + N{sub 2} as the feed to a packed bed of iron oxide particles, while measuring the concentrations of CO and CO{sub 2} in the off-gas; step 2 was investigated by passing steam in N{sub 2} through the packed bed and measuring the quantity of H{sub 2} produced. The third step simply involved passing air through the bed. Reduction to Fe, rather than Fe{sub 0.947}O, in step 1 gave low levels of H{sub 2} in step 2 after 10 cycles of reduction and oxidation and led to the deposition of carbon at lower temperature. Step 3, i.e. reoxidizing the particles in air to Fe{sub 2}O{sub 3}, led to no deterioration of the hydrogen yield in step 2 and benefited the process by (I) increasing the heat produced in each redox cycle and (ii) preventing the slip of CO from the bed in step 1. The proposed process is exothermic overall and very usefully generates separate streams of very pure H{sub 2} and CO, without complicated separation units.

  14. Selection and preparation of activated carbon for fuel gas storage

    DOEpatents

    Schwarz, James A.; Noh, Joong S.; Agarwal, Rajiv K.

    1990-10-02

    Increasing the surface acidity of active carbons can lead to an increase in capacity for hydrogen adsorption. Increasing the surface basicity can facilitate methane adsorption. The treatment of carbons is most effective when the carbon source material is selected to have a low ash content i.e., below about 3%, and where the ash consists predominantly of alkali metals alkali earth, with only minimal amounts of transition metals and silicon. The carbon is washed in water or acid and then oxidized, e.g. in a stream of oxygen and an inert gas at an elevated temperature.

  15. TESTING GUIDELINES FOR TECHNETIUM-99 ABSORPTION ON ACTIVATED CARBON

    SciTech Connect

    BYRNES ME

    2010-09-08

    CH2M HILL Plateau Remediation Company (CHPRC) is currently evaluating the potential use of activated carbon adsorption for removing technetium-99 from groundwater as a treatment method for the Hanford Site's 200 West Area groundwater pump-and-treat system. The current pump-and-treat system design will include an ion-exchange (IX) system for selective removal of technetium-99 from selected wells prior to subsequent treatment of the water in the central treatment system. The IX resin selected for technetium-99 removal is Purolite A530E. The resin service life is estimated to be approximately 66.85 days at the design technetium-99 loading rate, and the spent resin must be replaced because it cannot be regenerated. The resulting operating costs associated with resin replacement every 66.85 days are estimated at $0.98 million/year. Activated carbon pre-treatment is being evaluated as a potential cost-saving measure to offset the high operating costs associated with frequent IX resin replacement. This document is preceded by the Literature Survey of Technetium-99 Groundwater Pre-Treatment Option Using Granular Activated Carbon (SGW-43928), which identified and evaluated prior research related to technetium-99 adsorption on activated carbon. The survey also evaluated potential operating considerations for this treatment approach for the 200 West Area. The preliminary conclusions of the literature survey are as follows: (1) Activated carbon can be used to selectively remove technetium-99 from contaminated groundwater. (2) Technetium-99 adsorption onto activated carbon is expected to vary significantly based on carbon types and operating conditions. For the treatment approach to be viable at the Hanford Site, activated carbon must be capable of achieving a designated minimum technetium-99 uptake. (3) Certain radionuclides known to be present in 200 West Area groundwater are also likely to adsorb onto activated carbon. (4) Organic solvent contaminants of concern (COCs) will

  16. Complement activation and protein adsorption by carbon nanotubes.

    PubMed

    Salvador-Morales, Carolina; Flahaut, Emmanuel; Sim, Edith; Sloan, Jeremy; Green, Malcolm L H; Sim, Robert B

    2006-02-01

    As a first step to validate the use of carbon nanotubes as novel vaccine or drug delivery devices, their interaction with a part of the human immune system, complement, has been explored. Haemolytic assays were conducted to investigate the activation of the human serum complement system via the classical and alternative pathways. Western blot and sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) techniques were used to elucidate the mechanism of activation of complement via the classical pathway, and to analyse the interaction of complement and other plasma proteins with carbon nanotubes. We report for the first time that carbon nanotubes activate human complement via both classical and alternative pathways. We conclude that complement activation by nanotubes is consistent with reported adjuvant effects, and might also in various circumstances promote damaging effects of excessive complement activation, such as inflammation and granuloma formation. C1q binds directly to carbon nanotubes. Protein binding to carbon nanotubes is highly selective, since out of the many different proteins in plasma, very few bind to the carbon nanotubes. Fibrinogen and apolipoproteins (AI, AIV and CIII) were the proteins that bound to carbon nanotubes in greatest quantity.

  17. 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.

  18. Microbial community distribution and extracellular enzyme activities in leach bed reactor treating food waste: effect of different leachate recirculation practices.

    PubMed

    Xu, Su Yun; Karthikeyan, Obuli P; Selvam, Ammaiyappan; Wong, Jonathan W C

    2014-09-01

    This study aimed at understanding the relationship between microbial community and extracellular enzyme activities of leach bed reactor (LBR) treating food waste under different leachate recirculation practices (once per day and continuous) and liquid to solid (L/S) ratios (1:1 and 0.5:1). Microbial community analysis using PCR-DGGE revealed that Lactobacillus sp., Bifidobacter sp., and Proteobacteria were the most abundant species. Number of phylotypes was higher in LBRs with intermittent recirculation; whereas, lower number of phylotypes dominated by the key players of degradation was observed with continuous recirculation. The L/S ratio of 1:1 significantly enhanced the volatile solids removal compared with 0.5:1; however, this effect was insignificant under once a day leachate recirculation. Continuous leachate recirculation with 1:1 L/S ratio significantly improved the organic leaching (240 g COD/kgvolatile solid) and showed distinct extracellular enzyme activities suitable for food waste acidogenesis.

  19. Sustainable Regeneration of Nanoparticle Enhanced Activated Carbon in Water

    EPA Science Inventory

    The regeneration and reuse of exhausted granular activated carbon (GAC) is an appropriate method for lowering operational and environmental costs. Advanced oxidation is a promising environmental friendly technique for GAC regeneration. The main objective of this research was to ...

  20. GRANULAR ACTIVATED CARBON ADSORPTION AND INFRARED REACTIVATION: A CASE STUDY

    EPA Science Inventory

    A study evaluated the effectiveness and cost of removing trace organic contaminants and surrogates from drinking water by granular activated carbon (GAC) adsorption. The effect of multiple reactivations of spent GAC was also evaluated. Results indicated that reactivated GAC eff...

  1. [Influence of biological activated carbon dosage on landfill leachate treatment].

    PubMed

    Cui, Yan-Rui; Guo, Yan; Wu, Qing

    2014-08-01

    Effects of biological activated carbon (BAC) dosage on COD removal in landfill leachate treatment were compared. The COD removal efficiency of reactors with 0, 100 and 300 g activated carbon dosage per litre activated sludge was 12.9%, 19.6% and 27.7%, respectively. The results indicated that BAC improved the refractory organic matter removal efficiency and there was a positive correlation between COD removal efficiency and BAC dosage. The output of carbon dioxide after 8h of aeration in reactors was 109, 193 and 306 mg corresponding to the activated carbon dosages mentioned above, which indicated the amount of biodegradation and BAC dosage also had a positive correlation. The combination of adsorption and bioregeneration of BAC resulted in the positive correlation betweem organic matter removal efficiency and BAC dosage, and bioregeneration was the root cause for the microbial decomposition of refractory organics.

  2. Adsorption of dichlorodifluoromethane, chlorodifluoromethane, and chloropentafluoroethane on activated carbon

    SciTech Connect

    Berlier, K.; Frere, M.; Bougard, J.

    1995-09-01

    The CFCs (chlorofluorocarbons) are used as working refrigerant fluids. Recent concerns of the effects of CFCs on the ozone layer requires the development of efficient recovery methods. One technique is to adsorb the fluids onto a porous medium such as silica gel or activated carbon. Isotherms and enthalpies of adsorption curves of dichlorodifluoromethane (R12), chlorodifluoromethane (R22), and chloropentafluoroethane (R115) on three different activated carbons have been obtained at 303 K and at pressures to 602 kPa.

  3. Carbon Nanotube Materials for Substrate Enhanced Control of Catalytic Activity

    SciTech Connect

    Heben, M.; Dillon, A. C.; Engtrakul, C.; Lee, S.-H.; Kelley, R. D.; Kini, A. M.

    2007-05-01

    Carbon SWNTs are attractive materials for supporting electrocatalysts. The properties of SWNTs are highly tunable and controlled by the nanotube's circumferential periodicity and their surface chemistry. These unique characteristics suggest that architectures constructed from these types of carbon support materials would exhibit interesting and useful properties. Here, we expect that the structure of the carbon nanotube support will play a major role in stabilizing metal electrocatalysts under extreme operating conditions and suppress both catalyst and support degradation. Furthermore, the chemical modification of the carbon nanotube surfaces can be expected to alter the interface between the catalyst and support, thus, enhancing the activity and utilization of the electrocatalysts. We plan to incorporate discrete reaction sites into the carbon nanotube lattice to create intimate electrical contacts with the catalyst particles to increase the metal catalyst activity and utilization. The work involves materials synthesis, design of electrode architectures on the nanoscale, control of the electronic, ionic, and mass fluxes, and use of advanced optical spectroscopy techniques.

  4. Preparation and characterization of activated carbon from sugarcane bagasse by physical activation with CO2 gas

    NASA Astrophysics Data System (ADS)

    Bachrun, Sutrisno; AyuRizka, Noni; Annisa, SolichaHidayat; Arif, Hidayat

    2016-01-01

    A series of experiments have been conducted to study the effects of different carbonization temperatures (400, 600, and 800oC) on characteristics of porosity in activated carbon derived from carbonized sugarcane bagassechar at activation temperature of 800oC. The results showed that the activated carbon derived from high carbonized temperature of sugarcane bagassechars had higher BET surface area, total volume, micropore volume and yield as compared to the activated carbon derived from low carbonized temperature. The BET surface area, total volume and micropore volume of activated carbon prepared from sugarcane bagassechars obtained at 800oC of carbonized temperature and activation time of 120 min were 661.46m2/g, 0.2455cm3/g and 0.1989cm3/g, respectively. The high carbonization temperature (800oC) generated a highly microporous carbonwith a Type-I nitrogen adsorption isotherm, while the low carbonization temperature (400 and 600oC) generated a mesoporous one with an intermediate between types I and IInitrogen adsorption isotherm.

  5. The effects of repeated cycles of calcination and carbonation on a variety of different limestones, as measured in a hot fluidized bed of sand

    SciTech Connect

    Paul S. Fennell; Roberta Pacciani; John S. Dennis; John F. Davidson; Allan N. Hayhurst

    2007-08-15

    The capacity of calcined limestone to react repeatedly with CO{sub 2}, according to CaO{sub cr} + CO{sub 2(g)} = CaCO{sub 3(cr)} (eq I), and also its regeneration in the reverse reaction have been studied in a small, electrically heated fluidized bed of sand, for five different limestones. The forward step of eq I is a promising way of removing CO{sub 2} from the exhaust of, for example, a coal-fired power station, ready for sequestration or as part of a scheme to generate H{sub 2} using an enhanced water-gas shift reaction. The reverse step regenerates the sorbent. The uptake of CO{sub 2} by CaO, produced by calcining limestone, was measured using a bed of sand fluidized by N{sub 2} at about 1023 K. For each experiment, a small quantity of limestone particles was added to the hot sand, whereupon the limestone calcined to produce CaO. Calcination was completed in about 500 s for particles of a mean diameter of about 600 {mu}m. Next, CO{sub 2} was added to the fluidizing nitrogen to carbonate the CaO for about 500 s. Measurements of (CO{sub 2}) in the off-gases enabled the rates of calcination and the subsequent carbonation to be measured as functions of time. Many successive cycles of calcination and carbonation were studied. The forward step of reaction I is shown to exhibit an apparent final conversion, which decreases with the number of cycles of reaction; the final conversion fits well to a correlation from the literature. The reverse (calcination) reaction always proceeded to completion. It was found that the carrying capacity of CaO for CO{sub 2} on the nth cycle of carbonation was roughly proportional to the voidage inside pores narrower than about 150 nm in the calcined CaO before carbonation began. Thus, morphological changes, including reduction in the volume of pores narrower than 150 nm within a calcined limestone, were found to be responsible for much of the fall in conversion of reaction I with increasing numbers of cycles. 19 refs., 9 figs., 4 tabs.

  6. Application of a fluidized bed reactor charged with aragonite for control of alkalinity, pH and carbon dioxide in marine recirculating aquaculture systems

    USGS Publications Warehouse

    Paul S Wills, PhD; Pfeiffer, Timothy; Baptiste, Richard; Watten, Barnaby J.

    2016-01-01

    Control of alkalinity, dissolved carbon dioxide (dCO2), and pH are critical in marine recirculating aquaculture systems (RAS) in order to maintain health and maximize growth. A small-scale prototype aragonite sand filled fluidized bed reactor was tested under varying conditions of alkalinity and dCO2 to develop and model the response of dCO2 across the reactor. A large-scale reactor was then incorporated into an operating marine recirculating aquaculture system to observe the reactor as the system moved toward equilibrium. The relationship between alkalinity dCO2, and pH across the reactor are described by multiple regression equations. The change in dCO2 across the small-scale reactor indicated a strong likelihood that an equilibrium alkalinity would be maintained by using a fluidized bed aragonite reactor. The large-scale reactor verified this observation and established equilibrium at an alkalinity of approximately 135 mg/L as CaCO3, dCO2 of 9 mg/L, and a pH of 7.0 within 4 days that was stable during a 14 day test period. The fluidized bed aragonite reactor has the potential to simplify alkalinity and pH control, and aid in dCO2 control in RAS design and operation. Aragonite sand, purchased in bulk, is less expensive than sodium bicarbonate and could reduce overall operating production costs.

  7. 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.

  8. Fluidized bed deposition of diamond

    DOEpatents

    Laia, Jr., Joseph R.; Carroll, David W.; Trkula, Mitchell; Anderson, Wallace E.; Valone, Steven M.

    1998-01-01

    A process for coating a substrate with diamond or diamond-like material including maintaining a substrate within a bed of particles capable of being fluidized, the particles having substantially uniform dimensions and the substrate characterized as having different dimensions than the bed particles, fluidizing the bed of particles, and depositing a coating of diamond or diamond-like material upon the substrate by chemical vapor deposition of a carbon-containing precursor gas mixture, the precursor gas mixture introduced into the fluidized bed under conditions resulting in excitation mechanisms sufficient to form the diamond coating.

  9. Activated carbon fiber composite material and method of making

    DOEpatents

    Burchell, Timothy D.; Weaver, Charles E.; Chilcoat, Bill R.; Derbyshire, Frank; Jagtoyen, Marit

    2000-01-01

    An activated carbon fiber composite for separation and purification, or catalytic processing of fluids is described. The activated composite comprises carbon fibers rigidly bonded to form an open, permeable, rigid monolith capable of being formed to near-net-shape. Separation and purification of gases are effected by means of a controlled pore structure that is developed in the carbon fibers contained in the composite. The open, permeable structure allows the free flow of gases through the monolith accompanied by high rates of adsorption. By modification of the pore structure and bulk density the composite can be rendered suitable for applications such as gas storage, catalysis, and liquid phase processing.

  10. Activated carbon fiber composite material and method of making

    DOEpatents

    Burchell, Timothy D.; Weaver, Charles E.; Chilcoat, Bill R.; Derbyshire, Frank; Jagtoyen, Marit

    2001-01-01

    An activated carbon fiber composite for separation and purification, or catalytic processing of fluids is described. The activated composite comprises carbon fibers rigidly bonded to form an open, permeable, rigid monolith capable of being formed to near-net-shape. Separation and purification of gases are effected by means of a controlled pore structure that is developed in the carbon fibers contained in the composite. The open, permeable structure allows the free flow of gases through the monolith accompanied by high rates of adsorption. By modification of the pore structure and bulk density the composite can be rendered suitable for applications such as gas storage, catalysis, and liquid phase processing.

  11. Water vapor adsorption on activated carbon preadsorbed with naphtalene.

    PubMed

    Zimny, T; Finqueneisel, G; Cossarutto, L; Weber, J V

    2005-05-01

    The adsorption of water vapor on a microporous activated carbon derived from the carbonization of coconut shell has been studied. Preadsorption of naphthalene was used as a tool to determine the location and the influence of the primary adsorbing centers within the porous structure of active carbon. The adsorption was studied in the pressure range p/p0=0-0.95 in a static water vapor system, allowing the investigation of both kinetic and equilibrium experimental data. Modeling of the isotherms using the modified equation of Do and Do was applied to determine the effect of preadsorption on the mechanism of adsorption. PMID:15797395

  12. DESIGNING FIXED-BED ADSORBERS TO REMOVE MIXTURES OF ORGANICS.

    EPA Science Inventory

    A liquid-phase granular activated carbon (GAC) pilot plant and a full-scale GAC adsorber were designed, built, and operated in order to evaluate their performance for treating a groundwater contaminated with several volatile and synthetic organic chemicals. Several empty bed con...

  13. Carbon-Carbon Bond Cleavage in Activation of the Prodrug Nabumetone

    PubMed Central

    Varfaj, Fatbardha; Zulkifli, Siti N. A.; Park, Hyoung-Goo; Challinor, Victoria L.; De Voss, James J.

    2014-01-01

    Carbon-carbon bond cleavage reactions are catalyzed by, among others, lanosterol 14-demethylase (CYP51), cholesterol side-chain cleavage enzyme (CYP11), sterol 17β-lyase (CYP17), and aromatase (CYP19). Because of the high substrate specificities of these enzymes and the complex nature of their substrates, these reactions have been difficult to characterize. A CYP1A2-catalyzed carbon-carbon bond cleavage reaction is required for conversion of the prodrug nabumetone to its active form, 6-methoxy-2-naphthylacetic acid (6-MNA). Despite worldwide use of nabumetone as an anti-inflammatory agent, the mechanism of its carbon-carbon bond cleavage reaction remains obscure. With the help of authentic synthetic standards, we report here that the reaction involves 3-hydroxylation, carbon-carbon cleavage to the aldehyde, and oxidation of the aldehyde to the acid, all catalyzed by CYP1A2 or, less effectively, by other P450 enzymes. The data indicate that the carbon-carbon bond cleavage is mediated by the ferric peroxo anion rather than the ferryl species in the P450 catalytic cycle. CYP1A2 also catalyzes O-demethylation and alcohol to ketone transformations of nabumetone and its analogs. PMID:24584631

  14. Electrochemical characterisation of activated carbon particles used in redox flow battery electrodes

    NASA Astrophysics Data System (ADS)

    Radford, G. J. W.; Cox, J.; Wills, R. G. A.; Walsh, F. C.

    The Faradaic and non-Faradaic characteristics of a series of activated carbon particles (used to produce composite carbon-polymer electrodes for redox flow cells) have been determined using aqueous electrolytes (sulfuric acid and sodium polysulfide) at 295 K. The particles were mounted as a circular section (ca. 0.80 cm 2) shallow packed bed of 2.5 mm thickness in the direction of electrolyte flow (mean linear flow velocity ≈ 6 mm s -1). Cyclic voltammetry in deaerated, 1 mol dm -3 H 2SO 4 at 295 K indicated a specific capacitance in the range of 50-140 F g -1. Linear sweep voltammetry and galvanostatic step studies in an alkaline sodium polysulfide electrolyte (1.8 mol dm -3 Na 2S 2.11) have demonstrated marked differences amongst various types of activated carbon. Such differences are highlighted during galvanostatic charge-discharge cycling of half-cell electrodes in the polysulfide electrolyte. The electrochemical characteristics are compared to those based on (N 2 adsorption) gas porosimetry measurements.

  15. Influence of COD/N ratio and carbon source on nitrogen removal in a structured-bed reactor subjected to recirculation and intermittent aeration (SBRRIA).

    PubMed

    Santos, Carla E D; Moura, Rafael B; Damianovic, Márcia H R Z; Foresti, Eugenio

    2016-01-15

    This study aimed to evaluate the influence of COD/N ratio and carbon source on simultaneous nitrogen and carbon removal processes. A continuous up-flow structured-bed reactor subjected to recirculation and intermittent aeration (SBRRIA) was operated with hydraulic retention time (HRT) of 11.2 ± 0.6 h. The carbon sources were meat peptone and sucrose. The COD/N ratio varied by maintaining the organic loading rate fixed at 1.07 kg COD m(-3) d(-1) and changing the total-N concentration. The COD/N ratios tested were 9.7 ± 1 (sucrose); 7.6 ± 1 (meat peptone); 2.9 ± 1 (meat peptone) and 2.9 ± 0.4 (sucrose). COD removal efficiencies remained above 90% in all experimental phases. At lower COD/N ratios, NH4(+)-N oxidation efficiencies were higher than 90%. An autotrophic metabolism by anammox process was observed in Phases III and IV, which was responsible for 35% and 27% of total-N loading removal rates, respectively. Therefore, the system achieved total nitrogen removal efficiencies of 84.6 ± 10.1 and 81.5 ± 5.3%, under low availability of organic electron donors.

  16. The Formation of Carbon Nanofibers on Powdered Activated Carbon Impregnated with Nickel

    NASA Astrophysics Data System (ADS)

    Ahmed, Y. M.; Al-Mamun, A. A.; Muyibi, S. A.; Al-Khatib, M. F. R.; Jameel, A. T.; AlSaadi, M. A.

    2009-06-01

    In the present work, the production and characterization of carbon nanofibers (CNFs) composite is reported. Carbon nanofibers (CNF) were produced on powdered activated carbon PAC—impregnated with nickel—by Chemical Vapor Deposition (CVD) of a hydrocarbon in the presence of hydrogen at ˜780° C. The flow rates of carbon source and hydrogen were fixed. The CNFs were formed directly over the impregnated AC. Variable weight percentage ratios of the catalyst salt (Ni+2) were used for the impregnation (1, 3, 5, 7 and 9%, respectively). The product displays a relatively high surface area, essentially constituted by the external surface, and the absence of the bottled pores encountered with activated carbon. FSEM, TEM and TGA were used for the characterization of the product.

  17. Waste polyvinylchloride derived pitch as a precursor to develop carbon fibers and activated carbon fibers.

    PubMed

    Qiao, W M; Yoon, S H; Mochida, I; Yang, J H

    2007-01-01

    Polyvinylchloride (PVC) was successfully recycled through the solvent extraction from waste pipe with an extraction yield of ca. 86%. The extracted PVC was pyrolyzed by a two-stage process (260 and 410 degrees C) to obtain free-chlorine PVC based pitch through an effective removal of chlorine from PVC during the heat-treatment. As-prepared pitch (softening point: 220 degrees C) was spun, stabilized, carbonized into carbon fibers (CFs), and further activated into activated carbon fibers (ACFs) in a flow of CO2. As-prepared CFs show comparable mechanical properties to commercial CFs, whose maximum tensile strength and modulus are 862 MPa and 62 GPa, respectively. The resultant ACFs exhibit a high surface area of 1200 m2/g, narrow pore size distribution and a low oxygen content of 3%. The study provides an effective insight to recycle PVC from waste PVC and develop a carbon precursor for high performance carbon materials such as CFs and ACFs.

  18. Numerical Analysis of Carbon Monoxide-Hydrogen Gas Reduction of Iron Ore in a Packed Bed by an Euler-Lagrange Approach

    NASA Astrophysics Data System (ADS)

    Natsui, Shungo; Kikuchi, Tatsuya; Suzuki, Ryosuke O.

    2014-12-01

    In recent years, various methods to decrease carbon dioxide emissions from iron and steel making industries have been developed. The latest blast furnace operation design is intended to induce the low reducing agent operation, highly reactive material is considered a promising way to improve reaction efficiency. Another method utilizes hydrogen in the blast furnace process for highly efficient reduction. Mathematical modeling may help to predict complex in-furnace phenomena, including momentum, heat, and mass transport. However, the current macroscopic continuum model gives no information on the individual particles. In this work, a new approach based on the discrete element method was introduced to consider the interaction between particles under fluid flow in accordance with the arrangement and properties of individual particles. We used an Euler-Lagrange method to precisely understand the influence of the reaction conditions on the behavior of coke and ore particles in three dimensions. The heterogeneity of the reaction rate and temperature distribution was observed to be influenced by the particle arrangement. The endothermic and exothermic reactions influenced each other in the packed bed. Temperature distributions nearly correlated with the gas velocity distribution because convection processes greatly affected the reaction rate. Although convection heat transfer was not a dominant issue in the packed bed, promotion of the reaction by a gas flow was effective.

  19. The effect of ocean acidification on carbon storage and sequestration in seagrass beds; a global and UK context.

    PubMed

    Garrard, Samantha L; Beaumont, Nicola J

    2014-09-15

    Ocean acidification will have many negative consequences for marine organisms and ecosystems, leading to a decline in many ecosystem services provided by the marine environment. This study reviews the effect of ocean acidification (OA) on seagrasses, assessing how this may affect their capacity to sequester carbon in the future and providing an economic valuation of these changes. If ocean acidification leads to a significant increase in above- and below-ground biomass, the capacity of seagrass to sequester carbon will be significantly increased. The associated value of this increase in sequestration capacity is approximately £500 and 600 billion globally between 2010 and 2100. A proportionally similar increase in carbon sequestration value was found for the UK. This study highlights one of the few positive stories for ocean acidification and underlines that sustainable management of seagrasses is critical to avoid their continued degradation and loss of carbon sequestration capacity.

  20. Use of an in vitro flat-bed biofilm model to measure biologically active anti-odour compounds.

    PubMed

    Saad, S; Hewett, K; Greenman, J

    2013-09-01

    The objective of this study was to demonstrate the utility of a modified flat-bed perfusion biofilm matrix system for testing toothpaste formulations directly, without dilution, as a layer in direct contact with the biofilm matrix surface. Final biofilm yields and volatile sulphur compounds (VSC) biogenesis were measured to show the relative efficacy of toothpaste formulations. Diffusion characteristics of the flat-bed system to exposure with Meridol® tooth and tongue gel (TTG; 1,400 ppm F(-) from amine fluoride/stannous fluoride, 0.5 % zinc lactate, oral malodour counteractives) was assessed using a bioluminescent target species Escherichia coli Nissle 1917/pGLITE coupled with a low-light photon camera to visualise the kill kinetics. Tongue-flora derived, mixed culture biofilms (n = 4) received 5, 15 and 30 min treatment with TTG, respectively, to determine the optimum time of exposure. VSC biogenesis was measured from headspace samples by gas chromatography prior to and following treatment of two daily applications for 4 days of treatment (TTG), positive control (CHX gel) and negative controls (placebo and sham treatment). Viable counts were performed at the end of experiments by destructive sampling of the biofilms and plating onto selective and non-selective agar. Following a single treatment with TTG, the E. coli biofilm with lux target gave >50 % reduction of luminescence within 2 to 3 h before recovering to a steady state over 10 h, suggesting biofilm cidal activity rather biostasis. For mixed culture biofilms, 15- and 30-min treatment exposure with TTG gave almost identical reductions in final biofilm yields. For comparing efficacy of treatments, biofilms treated with TTG gave greatest reductions in both pre-post levels of H2S (P < 0.01) and CH3SH (P < 0.05) and population yields at the end of the experiments (P < 0.001) compared to placebo and positive control. The in vitro flat-bed perfusion model may be used to replicate many of

  1. Use of an in vitro flat-bed biofilm model to measure biologically active anti-odour compounds.

    PubMed

    Saad, S; Hewett, K; Greenman, J

    2013-09-01

    The objective of this study was to demonstrate the utility of a modified flat-bed perfusion biofilm matrix system for testing toothpaste formulations directly, without dilution, as a layer in direct contact with the biofilm matrix surface. Final biofilm yields and volatile sulphur compounds (VSC) biogenesis were measured to show the relative efficacy of toothpaste formulations. Diffusion characteristics of the flat-bed system to exposure with Meridol® tooth and tongue gel (TTG; 1,400 ppm F(-) from amine fluoride/stannous fluoride, 0.5 % zinc lactate, oral malodour counteractives) was assessed using a bioluminescent target species Escherichia coli Nissle 1917/pGLITE coupled with a low-light photon camera to visualise the kill kinetics. Tongue-flora derived, mixed culture biofilms (n = 4) received 5, 15 and 30 min treatment with TTG, respectively, to determine the optimum time of exposure. VSC biogenesis was measured from headspace samples by gas chromatography prior to and following treatment of two daily applications for 4 days of treatment (TTG), positive control (CHX gel) and negative controls (placebo and sham treatment). Viable counts were performed at the end of experiments by destructive sampling of the biofilms and plating onto selective and non-selective agar. Following a single treatment with TTG, the E. coli biofilm with lux target gave >50 % reduction of luminescence within 2 to 3 h before recovering to a steady state over 10 h, suggesting biofilm cidal activity rather biostasis. For mixed culture biofilms, 15- and 30-min treatment exposure with TTG gave almost identical reductions in final biofilm yields. For comparing efficacy of treatments, biofilms treated with TTG gave greatest reductions in both pre-post levels of H2S (P < 0.01) and CH3SH (P < 0.05) and population yields at the end of the experiments (P < 0.001) compared to placebo and positive control. The in vitro flat-bed perfusion model may be used to replicate many of

  2. Nitrogen and carbon removal from synthetic wastewater in a vertical structured-bed reactor under intermittent aeration.

    PubMed

    Moura, Rafael B; Damianovic, Márcia H R Z; Foresti, Eugenio

    2012-05-15

    The removal of nitrogen and organic matter using a single reactor has been a common focus of investigation, and reactors operated in batch mode and under intermittent aeration have attracted special attention. This study aimed to evaluate the application of a new reactor configuration consisting of a fixed-bed reactor that was operated under conditions of continuous feeding and intermittent aeration. The reactor was built using acrylic, with a working volume of 6.1L. The fixed bed used for biomass support was composed of polyurethane foam cylinders vertically oriented inside the reaction zone. The reactor was operated under intermittent aeration (2h aerated and 1h non-aerated) and a recirculation ratio Q(r)/Q=5. Three different operating conditions (Phase I, Phase II, and Phase III) corresponding to hydraulic retention times (HRT) of 12h, 8h, and 10h, respectively, were tested. In Phase I, the system achieved total nitrogen (TN) and chemical oxygen demand (COD) removal efficiencies of 82% and 89%, respectively. At HRTs of 8 h and 10 h, the reactor was unstable with respect to TN removal, and the average resultant removal efficiencies were 49% and 45%, respectively. However, COD removal efficiencies remained high with mean values of 85% and 88% for Phases II and III, respectively. Based on these results, it can be concluded that this new reactor configuration constitutes an alternative method for effective removal of organic matter and nitrogen from wastewater.

  3. Nitrogen and carbon removal from synthetic wastewater in a vertical structured-bed reactor under intermittent aeration.

    PubMed

    Moura, Rafael B; Damianovic, Márcia H R Z; Foresti, Eugenio

    2012-05-15

    The removal of nitrogen and organic matter using a single reactor has been a common focus of investigation, and reactors operated in batch mode and under intermittent aeration have attracted special attention. This study aimed to evaluate the application of a new reactor configuration consisting of a fixed-bed reactor that was operated under conditions of continuous feeding and intermittent aeration. The reactor was built using acrylic, with a working volume of 6.1L. The fixed bed used for biomass support was composed of polyurethane foam cylinders vertically oriented inside the reaction zone. The reactor was operated under intermittent aeration (2h aerated and 1h non-aerated) and a recirculation ratio Q(r)/Q=5. Three different operating conditions (Phase I, Phase II, and Phase III) corresponding to hydraulic retention times (HRT) of 12h, 8h, and 10h, respectively, were tested. In Phase I, the system achieved total nitrogen (TN) and chemical oxygen demand (COD) removal efficiencies of 82% and 89%, respectively. At HRTs of 8 h and 10 h, the reactor was unstable with respect to TN removal, and the average resultant removal efficiencies were 49% and 45%, respectively. However, COD removal efficiencies remained high with mean values of 85% and 88% for Phases II and III, respectively. Based on these results, it can be concluded that this new reactor configuration constitutes an alternative method for effective removal of organic matter and nitrogen from wastewater. PMID:22277346

  4. Wet oxidative regeneration of activated carbon loaded with reactive dye.

    PubMed

    Shende, R V; Mahajani, V V

    2002-01-01

    Wet Oxidative Regeneration (WOR) of powdered activated carbon (PAC) and granular activated carbon (GAC) loaded with the reactive dyes, namely chemictive brilliant blue R and cibacron turquoise blue G, was studied. Attempts were made to regenerate the loaded carbons designated now as spent carbon. A slurry (10% w/v) of spent carbon in distilled water was oxidized by wet oxidation in the temperature range of 150-250 degrees C using oxygen partial pressures between 0.69-1.38 MPa in an 1 1 SS 316 autoclave. The percent regeneration was determined from a ratio, X(RC)/X(VC), corresponding to an equilibrium adsorption capacity of regenerated carbon/equilibrium adsorption capacity of virgin carbon from an initial adsorption period of 3 h. It was observed that the regeneration mainly occurred due to the oxidation of the adsorbates taking place on the surface of carbon. It was possible to regenerate the spent GAC and PAC to the extent of more than 98% (approximately X(RC)/X(VC) > 0.98) by wet oxidation. After four consecutive cycles of adsorption and regeneration using the same stocks of GAC, carbon weight loss observed at 200 degrees C was about 40%. SEM studies of the regenerated carbon showed widening of the pores and loss of structure between the adjacent pores as compared with the virgin carbon. PAC was found to be more suitable as compared with GAC for the adsorption and wet oxidative regeneration processes to treat the aqueous solution containing lower concentration of unhydrolyzed reactive dye. The suitability of wet oxidative regeneration is demonstrated at a bench scale to treat the synthetic reactive dye solution.

  5. Wet oxidative regeneration of activated carbon loaded with reactive dye.

    PubMed

    Shende, R V; Mahajani, V V

    2002-01-01

    Wet Oxidative Regeneration (WOR) of powdered activated carbon (PAC) and granular activated carbon (GAC) loaded with the reactive dyes, namely chemictive brilliant blue R and cibacron turquoise blue G, was studied. Attempts were made to regenerate the loaded carbons designated now as spent carbon. A slurry (10% w/v) of spent carbon in distilled water was oxidized by wet oxidation in the temperature range of 150-250 degrees C using oxygen partial pressures between 0.69-1.38 MPa in an 1 1 SS 316 autoclave. The percent regeneration was determined from a ratio, X(RC)/X(VC), corresponding to an equilibrium adsorption capacity of regenerated carbon/equilibrium adsorption capacity of virgin carbon from an initial adsorption period of 3 h. It was observed that the regeneration mainly occurred due to the oxidation of the adsorbates taking place on the surface of carbon. It was possible to regenerate the spent GAC and PAC to the extent of more than 98% (approximately X(RC)/X(VC) > 0.98) by wet oxidation. After four consecutive cycles of adsorption and regeneration using the same stocks of GAC, carbon weight loss observed at 200 degrees C was about 40%. SEM studies of the regenerated carbon showed widening of the pores and loss of structure between the adjacent pores as compared with the virgin carbon. PAC was found to be more suitable as compared with GAC for the adsorption and wet oxidative regeneration processes to treat the aqueous solution containing lower concentration of unhydrolyzed reactive dye. The suitability of wet oxidative regeneration is demonstrated at a bench scale to treat the synthetic reactive dye solution. PMID:11942707

  6. Biodegradation of benzotriazoles and hydroxy-benzothiazole in wastewater by activated sludge and moving bed biofilm reactor systems.

    PubMed

    Mazioti, Aikaterini A; Stasinakis, Athanasios S; Pantazi, Ypapanti; Andersen, Henrik R

    2015-09-01

    Two laboratory scale fully aerated continuous flow wastewater treatment systems were used to compare the removal of five benzotriazoles and one benzothiazole by suspended and attached growth biomass. The activated sludge system was operated under low organic loading conditions. The moving bed biofilm reactor (MBBR) system consisted of two serially connected reactors filled with K3-biocarriers. It was either operated under low or high organic loading conditions. Target compounds were removed partially and with different rates in tested systems. For MBBR, increased loading resulted in significantly lower biodegradation for 4 out of 6 examined compounds. Calculation of specific removal rates (normalized to biomass) revealed that attached biomass had higher biodegradation potential for target compounds comparing to suspended biomass. Clear differences in the biodegradation ability of attached biomass grown in different bioreactors of MBBR systems were also observed. Batch experiments showed that micropollutants biodegradation by both types of biomass is co-metabolic. PMID:26093257

  7. Biodegradation of benzotriazoles and hydroxy-benzothiazole in wastewater by activated sludge and moving bed biofilm reactor systems.

    PubMed

    Mazioti, Aikaterini A; Stasinakis, Athanasios S; Pantazi, Ypapanti; Andersen, Henrik R

    2015-09-01

    Two laboratory scale fully aerated continuous flow wastewater treatment systems were used to compare the removal of five benzotriazoles and one benzothiazole by suspended and attached growth biomass. The activated sludge system was operated under low organic loading conditions. The moving bed biofilm reactor (MBBR) system consisted of two serially connected reactors filled with K3-biocarriers. It was either operated under low or high organic loading conditions. Target compounds were removed partially and with different rates in tested systems. For MBBR, increased loading resulted in significantly lower biodegradation for 4 out of 6 examined compounds. Calculation of specific removal rates (normalized to biomass) revealed that attached biomass had higher biodegradation potential for target compounds comparing to suspended biomass. Clear differences in the biodegradation ability of attached biomass grown in different bioreactors of MBBR systems were also observed. Batch experiments showed that micropollutants biodegradation by both types of biomass is co-metabolic.

  8. 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.

  9. 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

  10. 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

  11. 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

  12. Preparation and evaluation of coal-derived activated carbons for removal of mercury vapor from simulated coal combustion flue fases

    USGS Publications Warehouse

    Hsi, H.-C.; Chen, S.; Rostam-Abadi, M.; Rood, M.J.; Richardson, C.F.; Carey, T.R.; Chang, R.

    1998-01-01

    Coal-derived activated carbons (CDACs) were tested for their suitability in removing trace amounts of vapor-phase mercury from simulated flue gases generated by coal combustion. CDACs were prepared in bench-scale and pilot-scale fluidized-bed reactors with a three-step process, including coal preoxidation, carbonization, and then steam activation. CDACs from high-organicsulfur Illinois coals had a greater equilibrium Hg0 adsorption capacity than activated carbons prepared from a low-organic-sulfur Illinois coal. When a low-organic-sulfur CDAC was impregnated with elemental sulfur at 600 ??C, its equilibrium Hg0 adsorption capacity was comparable to the adsorption capacity of the activated carbon prepared from the high-organicsulfur coal. X-ray diffraction and sulfur K-edge X-ray absorption near-edge structure examinations showed that the sulfur in the CDACs was mainly in organic forms. These results suggested that a portion of the inherent organic sulfur in the starting coal, which remained in the CDACs, played an important role in adsorption of Hg0. Besides organic sulfur, the BET surface area and micropore area of the CDACs also influenced Hg0 adsorption capacity. The HgCl2 adsorption capacity was not as dependent on the surface area and concentration of sulfur in the CDACs as was adsorption of Hg0. The properties and mercury adsorption capacities of the CDACs were compared with those obtained for commercial Darco FGD carbon.

  13. Effect of powdered activated carbon technology on short-cut nitrogen removal for coal gasification wastewater.

    PubMed

    Zhao, Qian; Han, Hongjun; Xu, Chunyan; Zhuang, Haifeng; Fang, Fang; Zhang, Linghan

    2013-08-01

    A combined process consisting of a powdered activated carbon technology (PACT) and short-cut biological nitrogen removal reactor (SBNR) was developed to enhance the removal efficiency of the total nitrogen (TN) from the effluent of an upflow anaerobic sludge bed (UASB) reactor, which was used to treat coal gasification wastewater (CGW). The SBNR performance was improved with the increasing of COD and TP removal efficiency via PACT. The average removal efficiencies of COD and TP in PACT were respectively 85.80% and 90.30%. Meanwhile, the NH3-N to NO2-N conversion rate was achieved 86.89% in SBNR and the total nitrogen (TN) removal efficiency was 75.54%. In contrast, the AOB in SBNR was significantly inhibited without PACT or with poor performance of PACT in advance, which rendered the removal of TN. Furthermore, PAC was demonstrated to remove some refractory compounds, which therefore improved the biodegradability of the coal gasification wastewater. PMID:23735800

  14. Development of an activated carbon-packed microbial bioelectrochemical system for azo dye degradation.

    PubMed

    Cardenas-Robles, Arely; Martinez, Eduardo; Rendon-Alcantar, Idelfonso; Frontana, Carlos; Gonzalez-Gutierrez, Linda

    2013-01-01

    A microbial bioelectrochemical reactor (BER) was employed for the degradation of azo dyes without the use of an external electron donor, using activated carbon (GAC) as a redox mediator. Contribution of pH values, open circuit potential (OCP), dye concentration and applied current were individually studied. A batch system and an upflow fixed bed bioreactor were built for analyzing the effect of the applied current on biodegradation of the azo dye Reactive Red 272. The presence of GAC (20% w/v) regulated both pH and OCP values in solution and led to a removal efficiency of 98%. Cyclic voltammetry results indicate a dependence of the electron transfer mechanism with the concentration of the azo compound. With these results, a continuous flow reactor operating with J=0.045 mA cm(-2), led to removal rates of 95% (± 3.5%) in a half-residence time of 1 hour. PMID:23128299

  15. Effect of powdered activated carbon technology on short-cut nitrogen removal for coal gasification wastewater.

    PubMed

    Zhao, Qian; Han, Hongjun; Xu, Chunyan; Zhuang, Haifeng; Fang, Fang; Zhang, Linghan

    2013-08-01

    A combined process consisting of a powdered activated carbon technology (PACT) and short-cut biological nitrogen removal reactor (SBNR) was developed to enhance the removal efficiency of the total nitrogen (TN) from the effluent of an upflow anaerobic sludge bed (UASB) reactor, which was used to treat coal gasification wastewater (CGW). The SBNR performance was improved with the increasing of COD and TP removal efficiency via PACT. The average removal efficiencies of COD and TP in PACT were respectively 85.80% and 90.30%. Meanwhile, the NH3-N to NO2-N conversion rate was achieved 86.89% in SBNR and the total nitrogen (TN) removal efficiency was 75.54%. In contrast, the AOB in SBNR was significantly inhibited without PACT or with poor performance of PACT in advance, which rendered the removal of TN. Furthermore, PAC was demonstrated to remove some refractory compounds, which therefore improved the biodegradability of the coal gasification wastewater.

  16. Activated Carbon Composites for Air Separation

    SciTech Connect

    Contescu, Cristian I; Baker, Frederick S; Tsouris, Costas; McFarlane, Joanna

    2008-03-01

    In continuation of the development of composite materials for air separation based on molecular sieving properties and magnetic fields effects, several molecular sieve materials were tested in a flow system, and the effects of temperature, flow conditions, and magnetic fields were investigated. New carbon materials adsorbents, with and without pre-loaded super-paramagnetic nanoparticles of Fe3O4 were synthesized; all materials were packed in chromatographic type columns which were placed between the poles of a high intensity, water-cooled, magnet (1.5 Tesla). In order to verify the existence of magnetodesorption effect, separation tests were conducted by injecting controlled volumes of air in a flow of inert gas, while the magnetic field was switched on and off. Gas composition downstream the column was analyzed by gas chromatography and by mass spectrometry. Under the conditions employed, the tests confirmed that N2 - O2 separation occurred at various degrees, depending on material's intrinsic properties, temperature and flow rate. The effect of magnetic fields, reported previously for static conditions, was not confirmed in the flow system. The best separation was obtained for zeolite 13X at sub-ambient temperatures. Future directions for the project include evaluation of a combined system, comprising carbon and zeolite molecular sieves, and testing the effect of stronger magnetic fields produced by cryogenic magnets.

  17. DEVELOPMENT OF ACTIVATED CARBONS FROM COAL COMBUSTION BY-PRODUCTS

    SciTech Connect

    Prof. Harold H. Schobert; Dr. M. Mercedes Maroto-Valer; Ms. Zhe Lu

    2001-09-29

    The implementation of increasingly stringent Clean Air Act Regulations by the coal utility industry has resulted in an increase in the concentration of unburned carbon in coal combustion fly ash. In 1999, around 6 million tons of unburned carbon were disposed in the US, due to the present lack of efficient routes for its utilization. However, unburned carbon is a potential precursor for the production of adsorbent carbons, since it has gone through a devolatilization process while in the combustor, and therefore, only requires to be activated. Accordingly, this report evaluates and compares several routes for the production of activated carbons from unburned carbon, including physical activation with steam or CO{sub 2}, and chemical activation using KOH pretreatment. During the present reporting period (June 30, 2000--June 29, 2001), Task 1 ''Procurement and characterization of CCBPs'' was concluded, including samples from pulverized utility boilers, a utility cyclone unit equipped with a beneficiation technology, a suspension-fired research boiler, and a class C fly ash. The characterization studies showed that the samples collected have significantly different carbon contents, as determined by the ASTM C114 procedure, with the sample from the cyclone unit containing the highest carbon content (LOI of {approx} 80%), since this unit has been retrofitted with a technology to separate the unburned carbon from the fly ash. The porosity of the samples assembled was characterized by N{sub 2} adsorption isotherms at 77K. The surface areas of the class F fly ash samples from pulverized coal combustors are between 30-40 m{sup 2}/g, while the samples from the suspension-fired research boiler had surface area around 115 m{sup 2}/g. As expected, the surface areas of the class C ash is much higher than that of the class F ashes, with values up to 390 m{sup 2}/g. In addition, during the current reporting period, also Task 2 ''Development of activated carbons'' and Task 3

  18. Time in Bed is Associated with Decreased Physical Activity and Higher BMI in Women Seeking Weight Loss Treatment.

    PubMed

    Hart, Chantelle N; Fava, Joseph L; Subak, Leslee L; Stone, Katie; Vittinghoff, Eric; Demos, Kathryn; O'Brien, Erin; Cairns, Alyssa; Wing, Rena

    2012-01-01

    Short sleep duration is associated with obesity risk. Despite calls to incorporate strategies to enhance sleep within the context of behavioral weight loss (BWL) treatment, little is known regarding the association between sleep and body mass index (BMI) among individuals presenting for BWL. Moreover, most research has focused on eating pathways linking sleep and BMI, and have not explored how sleep may impact engagement in physical activity. The purpose of the present study was to determine whether, in a sample of women seeking treatment for weight loss, there was an association between reported time in bed (TIB), higher BMI, lower physical activity, and less favorable dietary composition. Prior to randomization, 318 women completed measures of TIB, eating, and activity; weight and height were measured. Findings demonstrated that report of '6 hours or less' TIB/night was associated with higher BMI and lower reported physical activity compared to the referent (>7 to ≤ 8 hours/night). It was not associated with the number of reported calories consumed each day or with the percent of calories consumed from fat, carbohydrates or protein. Better understanding the role of sleep within the context of BWL treatment in women seems warranted.

  19. Alkali activation of recovered fuel-biofuel fly ash from fluidised-bed combustion: Stabilisation/solidification of heavy metals.

    PubMed

    Yliniemi, Juho; Pesonen, Janne; Tiainen, Minna; Illikainen, Mirja

    2015-09-01

    Recovered fuel-biofuel fly ash from a fluidized bed boiler was alkali-activated and granulated with a sodium-silicate solution in order to immobilise the heavy metals it contains. The effect of blast-furnace slag and metakaolin as co-binders were studied. Leaching standard EN 12457-3 was applied to evaluate the immobilisation potential. The results showed that Ba, Pb and Zn were effectively immobilised. However, there was increased leaching after alkali activation for As, Cu, Mo, Sb and V. The co-binders had minimal or even negative effect on the immobilisation. One exception was found for Cr, in which the slag decreased leaching, and one was found for Cu, in which the slag increased leaching. A sequential leaching procedure was utilized to gain a deeper understanding of the immobilisation mechanism. By using a sequential leaching procedure it is possible fractionate elements into watersoluble, acid-soluble, easily-reduced and oxidisable fractions, yielding a total 'bioavailable' amount that is potentially hazardous for the environment. It was found that the total bioavailable amount was lower following alkali activation for all heavy metals, although the water-soluble fraction was higher for some metals. Evidence from leaching tests suggests the immobilisation mechanism was chemical retention, or trapping inside the alkali activation reaction products, rather than physical retention, adsorption or precipitation as hydroxides. PMID:26054963

  20. Cannabidiol injected into the bed nucleus of the stria terminalis modulates baroreflex activity through 5-HT1A receptors.

    PubMed

    Alves, Fernando H F; Crestani, Carlos C; Gomes, Felipe V; Guimarães, Francisco S; Correa, Fernando M A; Resstel, Leonardo B M

    2010-09-01

    Cannabidiol (CBD) is a non-psychotomimetic constituent of the Cannabis sativa plant that inhibits behavioral and cardiovascular responses to aversive situations, facilitating 5-HT1A-mediated neurotransmission. Previous results from our group suggest that the bed nucleus of the stria terminalis (BNST) may be involved in CBD's anti-aversive effects. To investigate whether the cardiovascular effects of the CBD could involve a direct drug effect on the BNST, we evaluated the effects of CBD microinjection into this structure on baroreflex activity. We also verified whether these effects were mediated by the activation of 5-HT(1A) receptors. Bilateral microinjection of CBD (60 nmol/100 nL) into the BNST increased the bradycardiac response to arterial pressure increases. However, no changes were observed in tachycardiac responses evoked by arterial pressure decreases. Pretreatment of the BNST with the selective 5-HT(1A) receptor antagonist WAY100635 (0.37 nmol/100 nL) prevented CBD effects on the baroreflex activity. Moreover, microinjection of the 5-HT(1A) receptor agonist 8-OH-DPAT (4 nmol/100 nL) caused effects that were similar to those observed after the microinjection of CBD, which were also blocked by pretreatment with WAY100635. In conclusion, the present studies show that the microinjection of CBD into the BNST has a facilitatory influence on the baroreflex response to blood pressure increases, acting through the activation of 5-HT1A receptors. PMID:20621717

  1. Porous texture evolution in Nomex-derived activated carbon fibers.

    PubMed

    Villar-Rodil, S; Denoyel, R; Rouquerol, J; Martínez-Alonso, A; Tascón, J M D

    2002-08-01

    In the present work, the textural evolution of a series of activated carbon fibers with increasing burn-off degree, prepared by the pyrolysis and steam activation of Nomex aramid fibers, is followed by measurements of physical adsorption of N(2) (77 K) and CO(2) (273 K) and immersion calorimetry into different liquids (dichloromethane, benzene, cyclohexane). The immersion calorimetry results are discussed in depth, paying special attention to the choice of the reference material. The activated carbon fibers studied possess an essentially homogeneous microporous texture, which suggests that these materials may be applied in gas separation, either directly or with additional CVD treatment. PMID:16290775

  2. A comparison of the electrochemical behavior of carbon aerogels and activated carbon fiber cloths

    SciTech Connect

    Tran, T.D.; Alviso, C.T.; Hulsey, S.S.; Nielsen, J.K.; Pekala, R.W.

    1996-05-10

    Electrochemical capacitative behavior of carbon aerogels and commercial carbon fiber cloths was studied in 5M KOH, 3M sulfuric acid, and 0.5M tetrethylammonium tetrafluoroborate/propylene carbonate electrolytes. The resorcinol-formaldehyde based carbon aerogels with a range of denisty (0.2-0.85 g/cc) have open-cell structures with ultrafine pore sizes (5-50 nm), high surface area (400-700 m{sup 2}/g), and a solid matrix composed of interconnected particles or fibers with characteristic diameters of 10 nm. The commercial fiber cloths in the density range 0.2-04g/cc have high surface areas (1000-2500 m{sup 2}/g). The volumetric capacitances of high-density aerogels are shown to be comparable to or exceeding those from activated carbon fibers. Electrochemical behavior of these materials in various electrolytes is compared and related to their physical properties.

  3. Effects of resource activities upon repository siting and waste containment with reference to bedded salt

    SciTech Connect

    Ashby, J.; Rowe, J.

    1980-02-01

    The primary consideration for the suitability of a nuclear waste repository site is the overall ability of the repository to safely contain radioactive waste. This report is a discussion of the past, present, and future effects of resource activities on waste containment. Past and present resource activities which provide release pathways (i.e., leaky boreholes, adjacent mines) will receive initial evaluation during the early stages of any repository site study. However, other resource activities which may have subtle effects on containment (e.g., long-term pumping causing increased groundwater gradients, invasion of saline water causing lower retardation) and all potential future resource activities must also be considered during the site evaluation process. Resource activities will affect both the siting and the designing of repositories. Ideally, sites should be located in areas of low resource activity and low potential for future activity, and repository design should seek to eliminate or minimize the adverse effects of any resource activity. Buffer zones should be created to provide areas in which resource activities that might adversely affect containment can be restricted or curtailed. This could mean removing large areas of land from resource development. The impact of these frozen assets should be assessed in terms of their economic value and of their effect upon resource reserves. This step could require a major effort in data acquisition and analysis followed by extensive numerical modeling of regional fluid flow and mass transport. Numerical models should be used to assess the effects of resource activity upon containment and should include the cumulative effects of different resource activities. Analysis by other methods is probably not possible except for relatively simple cases.

  4. [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. PMID:21936376

  5. 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...

  6. Biofuel intercropping effects on soil carbon and microbial activity.

    PubMed

    Strickland, Michael S; Leggett, Zakiya H; Sucre, Eric B; Bradford, Mark A

    2015-01-01

    Biofuels will help meet rising demands for energy and, ideally, limit climate change associated with carbon losses from the biosphere to atmosphere. Biofuel management must therefore maximize energy production and maintain ecosystem carbon stocks. Increasingly, there is interest in intercropping biofuels with other crops, partly because biofuel production on arable land might reduce availability and increase the price of food. One intercropping approach involves growing biofuel grasses in forest plantations. Grasses differ from trees in both their organic inputs to soils and microbial associations. These differences are associated with losses of soil carbon when grasses become abundant in forests. We investigated how intercropping switchgrass (Panicum virgalum), a major candidate for cellulosic biomass production, in loblolly pine (Pinus taeda) plantations affects soil carbon, nitrogen, and microbial dynamics. Our design involved four treatments: two pine management regimes where harvest residues (i.e., biomass) were left in place or removed, and two switchgrass regimes where the grass was grown with pine under the same two biomass scenarios (left or removed). Soil variables were measured in four 1-ha replicate plots in the first and second year following switchgrass planting. Under switchgrass intercropping, pools of mineralizable and particulate organic matter carbon were 42% and 33% lower, respectively. These declines translated into a 21% decrease in total soil carbon in the upper 15 cm of the soil profile, during early stand development. The switchgrass effect, however, was isolated to the interbed region where switchgrass is planted. In these regions, switchgrass-induced reductions in soil carbon pools with 29%, 43%, and 24% declines in mineralizable, particulate, and total soil carbon, respectively. Our results support the idea that grass inputs to forests can prime the activity of soil organic carbon degrading microbes, leading to net reductions in stocks

  7. 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. PMID:25704972

  8. 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.

  9. Experimental Determination of the Effects Carbon Sequestration into Dolomite and Marl Beds of the Jefferson Formation, Montana

    NASA Astrophysics Data System (ADS)

    Mangini, S. A.; Skidmore, M. L.; Shaw, C. A.

    2014-12-01

    The Jefferson Formation is a Devonian carbonate that is currently being targeted for a pilot scale CO2 injection project in Toole County Montana. This experiment uses samples from an analogous outcrop to experimentally determine what the consequences of CO2 injection will be. Samples from two potential reservoir zones were quarried from an outcrop south of the drill site in Sun Canyon, Montana. One sample is from a highly porous dolomite. The second sample is from a marginally porous argillaceous carbonate. The purpose of these experiments is to determine whether carbonate minerals (in the marl and dolomite) and susceptible silicate minerals (in the marl) undergo in-situ "weathering" reactions when exposed to the high concentrations of carbonic acid generated by the dissolution of supercritical CO2 in formation water. The reactions of these minerals to carbonic acid has the potential to: 1.) open up pore space through dissolution; 2.) reduce pore space and/or close pore throats by precipitating new minerals, or 3.) cause little change if the reactions take place slowly. Cores were cut and their physical, chemical, and mineralogical properties analyzed. Mineralogy was determined by thin section analysis, X-ray diffraction, and SEM. Bulk composition was measured by XRF. Experiments exposed the cores to CO2 saturated brine in a flow-through reactor at conditions similar to those found in the subsurface (100C and 15MPa). Changes to the chemical composition of the brine were determined by withdrawing samples at regular intervals during the experiment and analyzing their contents with ion chromatography, spectrophotometry, and ICP-OES. The physical and mineralogical properties of the cores were analyzed after each experiment and compared to the initial conditions.

  10. Integrating powdered activated carbon into wastewater tertiary filter for micro-pollutant removal.

    PubMed

    Hu, Jingyi; Aarts, Annelies; Shang, Ran; Heijman, Bas; Rietveld, Luuk

    2016-07-15

    Integrating powdered activated carbon (PAC) into wastewater tertiary treatment is a promising technology to reduce organic micro-pollutant (OMP) discharge into the receiving waters. To take advantage of the existing tertiary filter, PAC was pre-embedded inside the filter bed acting as a fixed-bed adsorber. The pre-embedding (i.e. immobilization) of PAC was realized by direct dosing a PAC solution on the filter top, which was then promoted to penetrate into the filter media by a down-flow of tap water. In order to examine the effectiveness of this PAC pre-embedded filter towards OMP removal, batch adsorption tests, representing PAC contact reactor (with the same PAC mass-to-treated water volume ratio as in the PAC pre-embedded filter) were performed as references. Moreover, as a conventional dosing option, PAC was dosed continuously with the filter influent (i.e. the wastewater secondary effluent with the investigated OMPs). Comparative results confirmed a higher OMP removal efficiency associated with the PAC pre-embedded filter, as compared to the batch system with a practical PAC residence time. Furthermore, over a filtration period of 10 h (approximating a realistic filtration cycle for tertiary filters), the continuous dosing approach resulted in less OMP removal. Therefore, it was concluded that the pre-embedding approach can be preferentially considered when integrating PAC into the wastewater tertiary treatment for OMP elimination. PMID:27082256

  11. Seasonal changes in the invertebrate community of granular activated carbon filters and control technologies.

    PubMed

    Wang, Qing; You, Wei; Li, Xiaowei; Yang, Yufeng; Liu, Lijun

    2014-03-15

    Invertebrate colonization of granular activated carbon (GAC) filters in the waterworks is one of the most frequently occurring and least studied biological problems of water processing in China. A survey of invertebrate colonization of GAC filters was carried out weekly from October 2010 to December 2011 at a reservoir water treatment works in South China. Twenty-six kinds of invertebrates were observed. The abundance was as high as 5600ind.m(-3) with a mean of 860ind.m(-3). Large variations in abundance were observed among different seasons and before and after GAC filtration. The dominant organisms were rotifers and copepods. The average invertebrate abundance in the filtrate was 12-18.7 times of that in the pre-filtered water. Results showed that the GAC filters were colonized by invertebrates which may lead to a higher output of organisms in the filtrate than in the pre-filtered water. The invertebrate abundance in the GAC filters was statistically correlated with the water temperature. Seasonal patterns were observed. The invertebrate abundance grew faster in the spring and summer. Copepods were dominant in the summer while rotifers dominated in all other seasons of the year. There was a transition of small invertebrates (rotifers) gradually being substituted by larger invertebrates (copepods) from spring to summer. Control measures such as backwashing with chloric water, drying filter beds and soaking with saliferous water were implemented in the waterworks to reduce invertebrate abundances in the GAC filters. The results showed that soaking with saliferous water (99%, reduction in percent) was best but drying the filter beds (84%) was more economical. Soaking filter beds with 20g/L saliferous water for one day can be implemented in case of emergency. In order to keep invertebrate abundance in the acceptable range, some of these measures should be adopted.

  12. Soil moisture estimation by airborne active and passive microwave remote sensing: A test-bed for SMAP fusion algorithms

    NASA Astrophysics Data System (ADS)

    Montzka, Carsten; Bogena, Heye; Jagdhuber, Thomas; Hajnsek, Irena; Horn, Ralf; Reigber, Andreas; Hasan, Sayeh; Rüdiger, Christoph; Jaeger, Marc; Vereecken, Harry

    2014-05-01

    The objective of the NASA Soil Moisture Active & Passive (SMAP) mission is to provide global measurements of soil moisture and its freeze/thaw state. The SMAP launch is currently planned for 2014-2015. The SMAP measurement approach is to integrate L-band radar and L-band radiometer as a single observation system combining the respective strengths of active and passive remote sensing for enhanced soil moisture mapping. The radar and radiometer measurements can be effectively combined to derive soil moisture maps that approach the accuracy of radiometer-only retrievals, but with a higher resolution (being able to approach the radar resolution under some conditions). Aircraft and tower-based instruments will be a key part of the SMAP validation program. Here, we present an airborne campaign in the Rur catchment in Germany, in which the passive L-band system Polarimetric L-band Multi-beam Radiometer (PLMR2) and the active L-band system DLR F-SAR were flown on six dates in 2013. The flights covered the full heterogeneity of the area under investigation, i.e. all types of land cover and experimental monitoring sites. These data are used as a test-bed for the analysis of existing and development of new active-passive fusion techniques. A synergistic use of the two signals can help to decouple soil moisture effects from the effects of vegetation (or roughness) in a better way than in the case of a single instrument. In this study, we present and evaluate three approaches for the fusion of active and passive microwave records for an enhanced representation of the soil moisture status: i) estimation of soil moisture by passive sensor data and subsequent disaggregation by active sensor backscatter data, ii) disaggregation of passive microwave brightness temperature by active microwave backscatter and subsequent inversion to soil moisture, and iii) fusion of two single-source soil moisture products from radar and radiometer.

  13. Bed bug detection: current technologies and future directions.

    PubMed

    Vaidyanathan, Rajeev; Feldlaufer, Mark F

    2013-04-01

    Technologies to detect bed bugs have not kept pace with their global resurgence. Early detection is critical to prevent infestations from spreading. Detection based exclusively on bites is inadequate, because reactions to insect bites are non-specific and often misdiagnosed. Visual inspections are commonly used and depend on identifying live bugs, exuviae, or fecal droplets. Visual inspections are inexpensive, but they are time-consuming and unreliable when only a few bugs are present. Use of a dog to detect bed bugs is gaining in popularity, but it can be expensive, may unintentionally advertise a bed bug problem, and is not foolproof. Passive monitors mimic natural harborages; they are discreet and typically use an adhesive to trap bugs. Active monitors generate carbon dioxide, heat, a pheromone, or a combination to attract bed bugs to a trap. New technologies using DNA analysis, mass spectrometry, and electronic noses are innovative but impractical and expensive for widespread use. PMID:23553226

  14. Bed Bug Detection: Current Technologies and Future Directions

    PubMed Central

    Vaidyanathan, Rajeev; Feldlaufer, Mark F.

    2013-01-01

    Technologies to detect bed bugs have not kept pace with their global resurgence. Early detection is critical to prevent infestations from spreading. Detection based exclusively on bites is inadequate, because reactions to insect bites are non-specific and often misdiagnosed. Visual inspections are commonly used and depend on identifying live bugs, exuviae, or fecal droplets. Visual inspections are inexpensive, but they are time-consuming and unreliable when only a few bugs are present. Use of a dog to detect bed bugs is gaining in popularity, but it can be expensive, may unintentionally advertise a bed bug problem, and is not foolproof. Passive monitors mimic natural harborages; they are discreet and typically use an adhesive to trap bugs. Active monitors generate carbon dioxide, heat, a pheromone, or a combination to attract bed bugs to a trap. New technologies using DNA analysis, mass spectrometry, and electronic noses are innovative but impractical and expensive for widespread use. PMID:23553226

  15. Activation of galanin pathways across puberty in the male rat: galanin gene expression in the bed nucleus of the stria terminalis and medial amygdala.

    PubMed

    Planas, B; Kolb, P E; Raskind, M A; Miller, M A

    1994-12-01

    Galanin and vasopressin are coexpressed in the bed nucleus of the stria terminalis and medial amygdala of the male rat. In adult males, the level of gene expression for both peptides in these regions is dependent on circulating levels of testosterone. We hypothesized that galanin messenger RNA levels would be enhanced in adult males compared with prepubertal males due to the rise in plasma testosterone levels. We used in situ hybridization and quantitative autoradiography to measure galanin messenger RNA in cells of the bed nucleus of the stria terminalis and medial amygdala of prepubertal and adult male rats. Our results show that significantly (P < or = 0.05) more galanin messenger RNA expressing neurons are detectable in the bed nucleus of the stria terminalis of adult compared with prepubertal male rats. In contrast, no differences were observed between the groups in the number of labeled neurons detected within the medial amygdala. However, the average labeling intensity was significantly enhanced in both the bed nucleus of the stria terminalis (P < or = 0.001) and medial amygdala (P < or = 0.001) of adult compared with prepubertal animals. The present findings are consistent with the hypothesis that gonadal hormones regulate galanin gene expression in some brain regions and suggest that the activation of the hypothalamic-pituitary-gonadal axis which occurs naturally with puberty is associated with activation of galanin pathways in the bed nucleus of the stria terminalis and medial amygdala.

  16. Modeling the heat and mass transfers in temperature-swing adsorption of volatile organic compounds onto activated carbons

    SciTech Connect

    Sylvain Giraudet; Pascaline Pre; Pierre Le Cloirec

    2009-02-15

    A theoretical model was built to simulate the adsorption of volatile organic compounds (VOCs) onto activated carbons in a fixed bed. This model was validated on a set of experimental data obtained for the adsorption of acetone, ethyl formate, and dichloromethane onto five commercial activated carbons. The influence of operating conditions was modeled with various VOC contents at the inlet of the adsorber and superficial velocities of the gas-phase from 0.14 to 0.28 m.s{sup -1}. Breakthrough times and maximum temperature rises were computed with a coefficient of determination of 0.988 and 0.901, respectively. The simulation was then extended to the adsorption of mixtures of VOCs. From the comparison of simulation and experimental results, the advantage of accounting for dispersions of heat and mass is shown and the importance in taking into account the temperature effect on the equilibrium data is demonstrated. 29 refs., 6 figs., 1 tab.

  17. Diurnal time-activity budgets of redheads (Aythya americana) wintering in seagrass beds and coastal ponds in Louisiana and Texas

    USGS Publications Warehouse

    Michot, T.C.; Woodin, M.C.; Adair, S.E.; Moser, E.B.

    2006-01-01

    Diurnal time-activity budgets were determined for wintering redheads (Aythya americana) from estuarine seagrass beds in Louisiana (Chandeleur Sound) and Texas (Laguna Madre) and from ponds adjacent to the Laguna Madre. Activities differed (p<0.0001) by location, month, and diurnal time period. Resting and feeding were the most frequent activities of redheads at the two estuarine sites, whereas drinking was almost nonexistent. Birds on ponds in Texas engaged most frequently in resting and drinking, but feeding was very infrequent. Redheads from the Louisiana estuarine site rested less than birds in Texas at either the Laguna Madre or freshwater ponds. Redheads in Louisiana fed more than birds in Texas; this was partially because of weather differences (colder temperatures in Louisiana), but the location effect was still significant even when we adjusted the model for weather effects. Redheads in Louisiana showed increased resting and decreased feeding as winter progressed, but redheads in Texas did not exhibit a seasonal pattern in either resting or feeding. In Louisiana, birds maintained a high level of feeding activity during the early morning throughout the winter, whereas afternoon feeding tapered off in mid- to late-winter. Texas birds showed a shift from morning feeding in early winter to afternoon feeding in late winter. Males and females at both Chandeleur Sound and Laguna Madre showed differences in their activities, but because the absolute difference seldom exceeded 2%, biological significance is questionable. Diurnal time-activity budgets of redheads on the wintering grounds are influenced by water salinities and the use of dietary fresh water, as well as by weather conditions, tides, and perhaps vegetation differences between sites. The opportunity to osmoregulate via dietary freshwater, vs. via nasal salt glands, may have a significant effect on behavioral allocations. ?? Springer 2006.

  18. Bed exit alarms.

    PubMed

    2004-09-01

    Bed-exit alarms alert caregivers that a patient who should not get out of bed unassisted is doing so. These alarms can help reduce the likelihood of falls and can promote speedy assistance to patients who have already fallen. But as we described in our May 2004 Guidance Article on bed-exit alarms, they don't themselves prevent falls. They are only effective if used as part of an overall fall-prevention program and with a clear understanding of their limitations. This Evaluation examines the effectiveness of 16 bed-exit alarms from seven suppliers. Our ratings focus primarily on each product's reliability in detecting bed-exit events and alerting caregivers, its ability to minimize nuisance alarms (alarms that sound even though the patient isn't leaving the bed or that sound while a caregiver is helping the patient to leave the bed), and its resistance to deliberate or inadvertent tampering. Twelve of the products use pressure-sensor-activated alarms (mainly sensor pads placed on or under the mattress); three use a cord that can attach to the patient's garment, alarming if the cord is pulled loose from the control unit; and one is a position-sensitive alarm attached to a leg cuff. All the products reliably detect attempted or successful bed exits. But they vary greatly in how effectively they alert staff, minimize nuisance alarms, and resist tampering. Ease of use and battery performance also vary for many units. Of the pressure-sensor units, three are rated Preferred. Those units meet most of our criteria and have no significant disadvantages. Five of the other pressure-sensor products are Acceptable, and the remaining four are Not Recommended. All three cord-activated alarms are rated Acceptable, as is the patient-worn alarm.

  19. Modified Activated Carbon to be Used in Clinical Applications

    NASA Astrophysics Data System (ADS)

    Fernando, M. S.; de Silva, W. R. M.; de Silva, K. M. N.

    2014-11-01

    In this study a novel nano composite of hydroxyapatite nano particles impregnated activated carbon (C-HAp), which was synthesized in our own method, was used in iron adsorption studies. The study was conducted in order to investigate the potential of using C-HAp nanocomposite to be used in clinical detoxifications such as acute iron toxicity where the use of Activated carbon (GAC) is not very effective. Adsorption studies were conducted for synthetic solutions of Fe2+, Fe3+ and iron syrup using GAC, C-HAp and neat HAp as adsorbents. According to the results C-HAp nano composite showed improved properties than GAC in adsorbing Fe2+, Fe3+ and also Fe ions in iron syrup solutions. Thus the results of the in-vitro studies of iron adsorption studies indicated the potential of using C-HAp as an alternative to activated carbon in such clinical applications.

  20. Chars pyrolyzed from oil palm wastes for activated carbon preparation

    SciTech Connect

    Lua, A.C.; Guo, J.

    1999-01-01

    Chars pyrolyzed from extracted oil palm fibers for the preparation of activated carbons were studied. The effects of pyrolysis temperature and hold time on density, porosity, yield, BET and micropore surface areas, total pore volume, and pore size distributions of chars were investigated. The optimum conditions for pyrolysis were found to be at a pyrolysis temperature of 850 C for a hold time of 3.5 h. Scanning electron micrographs of the char surfaces verified the presence of porosities. The experimental results showed that it was feasible to produce chars with high BET and micropore surface areas from extracted oil palm fibers. The resulting chars will be subjected to steam or carbon dioxide activation to prepare activated carbons for use as gas adsorbents for air pollution control.

  1. Dissolution of bedded rock salt: A seismic profile across the active eastern margin of the Hutchinson Salt Member, central Kansas

    USGS Publications Warehouse

    Anderson, N.L.; Hopkins, J.; Martinez, A.; Knapp, R.W.; Macfarlane, P.A.; Watney, W.L.; Black, R.

    1994-01-01

    Since late Tertiary, bedded rock salt of the Permian Hutchinson Salt Member has been dissolved more-or-less continuously along its active eastern margin in central Kansas as a result of sustained contact with unconfined, undersaturated groundwater. The associated westward migration of the eastern margin has resulted in surface subsidence and the contemporaneous sedimentation of predominantly valley-filling Quarternary alluvium. In places, these alluvium deposits extend more than 25 km to the east of the present-day edge of the main body of contiguous rock salt. The margin could have receded this distance during the past several million years. From an environmental perspective, the continued leaching of the Hutchinson Salt is a major concern. This predominantly natural dissolution occurs in a broad zone across the central part of the State and adversely affects groundwater and surface-water quality as nonpoint source pollution. Significant surface subsidence occurs as well. Most of these subsidence features have formed gradually; others developed in a more catastrophic manner. The latter in particular pose real threats to roadways, railways, and buried oil and gas pipelines. In an effort to further clarify the process of natural salt dissolution in central Kansas and with the long-term goal of mitigating the adverse environmental affects of such leaching, the Kansas Geological Survey acquired a 4-km seismic profile across the eastern margin of the Hutchinson Salt in the Punkin Center area of central Kansas. The interpretation of these seismic data (and supporting surficial and borehole geologic control) is consistent with several hypotheses regarding the process and mechanisms of dissolution. More specifically these data support the theses that: 1. (1) Dissolution along the active eastern margin of the Hutchinson Salt Member was initiated during late Tertiary. Leaching has resulted in the steady westward migration of the eastern margin, surface subsidence, and the

  2. Dissolution of bedded rock salt: A seismic profile across the active eastern margin of the Hutchinson Salt Member, central Kansas

    NASA Astrophysics Data System (ADS)

    Anderson, Neil L.; Hopkins, John; Martinez, Alex; Knapp, Ralph W.; Macfarlane, P. Allan; Watney, W. Lynn; Black, Ross

    1994-06-01

    Since late Tertiary, bedded rock salt of the Permian Hutchinson Salt Member has been dissolved more-or-less continuously along its active eastern margin in central Kansas as a result of sustained contact with unconfined, undersaturated groundwater. The associated westward migration of the eastern margin has resulted in surface subsidence and the contemporaneous sedimentation of predominantly valley-filling Quarternary alluvium. In places, these alluvium deposits extend more than 25 km to the east of the present-day edge of the main body of contiguous rock salt. The margin could have receded this distance during the past several million years. From an environmental perspective, the continued leaching of the Hutchinson Salt is a major concern. This predominantly natural dissolution occurs in a broad zone across the central part of the State and adversely affects groundwater and surface-water quality as nonpoint source pollution. Significant surface subsidence occurs as well. Most of these subsidence features have formed gradually; others developed in a more catastrophic manner. The latter in particular pose real threats to roadways, railways, and buried oil and gas pipelines. In an effort to further clarify the process of natural salt dissolution in central Kansas and with the long-term goal of mitigating the adverse environmental affects of such leaching, the Kansas Geological Survey acquired a 4-km seismic profile across the eastern margin of the Hutchinson Salt in the Punkin Center area of central Kansas. The interpretation of these seismic data (and supporting surficial and borehole geologic control) is consistent with several hypotheses regarding the process and mechanisms of dissolution. More specifically these data support the theses that: (1) Dissolution along the active eastern margin of the Hutchinson Salt Member was initiated during late Tertiary. Leaching has resulted in the steady westward migration of the eastern margin, surface subsidence, and the

  3. 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.

  4. Improved granular activated carbon for the stabilization of wastewater PH

    SciTech Connect

    Farmer, R.W.; Dussert, B.W.; Kovacic, S.L.

    1996-12-31

    Laboratory studies have identified the cause of the pH rise, which occurs during water treatment with activated carbon, as an interaction between the naturally occurring anions and protons in the water and the carbon surface. The interaction can be described as an ion exchange type of phenomenon, in which the carbon surface sorbs the anions and corresponding hydronium ions from the water. These studies have shown that the anion sorption and resulting pH increase is independent of the raw material used for the activated carbon production, e.g. bituminous or subbituminous coal, peat, wood or coconut. Also, the pH excursions occur with virgin, reactivated, and acid washed granular carbons. Current pH control technologies focus on adjustment of the wastewater pH prior to discharge or recycle of the initial effluent water until the pH increase abates. However, improved water pH control options have been realized by altering the carbon surface through controlled oxidation rather than the water chemistry or extended preprocessing at the treatment site.

  5. MODELING THE INFLUENCE OF ACTIVE SUBSLAB DEPRESSURIZATION (ASD) SYSTEMS ON AIRFLOWS IN SUBSLAB AGGREGATE BEDS

    EPA Science Inventory

    A simple model is presented that allows the pressure difference in a subslab aggregate layer to be estimated as a function of radial distance from the central suction point of an active subslab depressurization system by knowing the average size, thickness, porosity, and permeabi...

  6. Role of predation by zooplankton in transport and fate of protozoan (oo)cysts in granular activated carbon filtration.

    PubMed

    Bichai, Françoise; Barbeau, Benoit; Dullemont, Yolanda; Hijnen, Wim

    2010-02-01

    The significance of zooplankton in the transport and fate of pathogenic organisms in drinking water is poorly understood, although many hints of the role of predation in the persistence of microorganisms through water treatment processes can be found in literature. The objective of this study was to assess the impact of predation by natural zooplankton on the transport and fate of protozoan (oo)cysts in granular activated carbon (GAC) filtration process. UV-irradiated unlabelled Cryptosporidium parvum and Giardia lamblia (oo)cysts were seeded into two pilot-scale GAC filtration columns operated under full-scale conditions. In a two-week period after seeding, a reduction of free (oo)cysts retained in the filter bed was observed. Zooplankton was isolated from the filter bed and effluent water on a 30 microm net before and during the two-week period after seeding; it was enumerated and identified. Rotifers, which are potential predators of (oo)cysts, accounted for the major part of the isolated zooplankton. Analytical methods were developed to detect (oo)cysts internalized in natural zooplankton isolated from the filter bed and effluent water. Sample sonication was optimized to disrupt zooplankton organisms and release internalized microorganisms. (Oo)cysts released from zooplankton after sonication were isolated by IMS and stained (EasyStain) for microscopic counting. Both Cryptosporidium and Giardia (oo)cysts were detected in association with zooplankton in the filter bed samples as well as in the effluent of GAC filters. The results of this study suggest that predation by zooplankton can play a role in the remobilization of persistent pathogens such as Cryptosporidium and Giardia (oo)cysts retained in GAC filter beds, and consequently in the transmission of these pathogens in drinking water.

  7. Assessment of Service Life for Regenerative ECLSS Resin Beds

    NASA Technical Reports Server (NTRS)

    Cloud, Dale L.; Keilich, Maria C.; Polis, Peter C.; Yanczura, Stephen J.

    2013-01-01

    The International Space Station (ISS) Water Processor Assembly (WPA) and Oxygen Generation Assembly (OGA) manage and process water at various levels of cleanliness for multiple purposes. The effluent of theWPA and the influent of the OGA require water at very high levels of purity. The bulk of the water purification that occurs in both systems is performed by consumable activated carbon and ion exchange resin beds. Replacement beds must be available on orbit in order to continue the ISS critical processes of water purification and oxygen generation. Various hurdles exist in order to ensure viable spare resin beds. These include the characteristics of resin beds such as: storage environment, shelf life requirements, microbial growth, and variations in the levels and species of contaminants the beds are required to remove. Careful consideration has been given to match water models, bed capacities and spares traffic models to ensure that spares are always viable. The results of these studies and considerations, in particular, how shelf life requirements affect resin bed life management, are documented in this paper.

  8. Carbon-Based Supercapacitors Produced by Activation of Graphene

    SciTech Connect

    Zhu, Y.; Su, D.; Murali, S.; Stoller, M.D.; Ganesh, K.J.; Cai, W.; Ferreira, P.J.; Pirkle, A.; Wallace, R.M.; Cychosz, K.A., Thommes, M.; Stach, E.A.; Ruoff, R.S.

    2011-06-24

    Supercapacitors, also called ultracapacitors or electrochemical capacitors, store electrical charge on high-surface-area conducting materials. Their widespread use is limited by their low energy storage density and relatively high effective series resistance. Using chemical activation of exfoliated graphite oxide, we synthesized a porous carbon with a Brunauer-Emmett-Teller surface area of up to 3100 square meters per gram, a high electrical conductivity, and a low oxygen and hydrogen content. This sp{sup 2}-bonded carbon has a continuous three-dimensional network of highly curved, atom-thick walls that form primarily 0.6- to 5-nanometer-width pores. Two-electrode supercapacitor cells constructed with this carbon yielded high values of gravimetric capacitance and energy density with organic and ionic liquid electrolytes. The processes used to make this carbon are readily scalable to industrial levels.

  9. Carbon-based Supercapacitors Produced by Activation of Graphene

    SciTech Connect

    Y Zhu; S Murali; M Stoller; K Ganesh; W Cai; P Ferreira; A Pirkle; R Wallace; K Cychosz; et al.

    2011-12-31

    Supercapacitors, also called ultracapacitors or electrochemical capacitors, store electrical charge on high-surface-area conducting materials. Their widespread use is limited by their low energy storage density and relatively high effective series resistance. Using chemical activation of exfoliated graphite oxide, we synthesized a porous carbon with a Brunauer-Emmett-Teller surface area of up to 3100 square meters per gram, a high electrical conductivity, and a low oxygen and hydrogen content. This sp{sup 2}-bonded carbon has a continuous three-dimensional network of highly curved, atom-thick walls that form primarily 0.6- to 5-nanometer-width pores. Two-electrode supercapacitor cells constructed with this carbon yielded high values of gravimetric capacitance and energy density with organic and ionic liquid electrolytes. The processes used to make this carbon are readily scalable to industrial levels.

  10. Electroadsorption of acilan blau dye from textile effluents by using activated carbon-perlite mixtures.

    PubMed

    Koparal, A S; Yavuz, Y; Bakir Ogütveren, U

    2002-01-01

    The feasibility of the removal of dye stuffs from textile effluents by electroadsorption has been investigated. An activated carbon-perlite mixture with a ratio of 8:1 for bipolarity has been used as the adsorbent. Conventional adsorption experiments have also been conducted for comparison. A bipolar trickle reactor has been used in the electroadsorption experiments. The model wastewater has been prepared by using acilan blau dye. Initial dye concentration, bed height between the electrodes, applied potential, flowrate, and the supporting electrolyte concentration have been examined as the parameters affecting the removal efficiency. A local textile plant effluent has been treated in the optimum values of these parameters obtained from the experimental studies. Adsorption kinetics and the amount of adsorbent required to reach the maximum removal efficiency have also been investigated and mass-transfer coefficients have been calculated for adsorption and electroadsorption. The results showed that a removal efficiency of up to 100% can be achieved with energy consumption values of 1.58 kWh/m3 of wastewater treated. However, energy consumption decreases to 0.09 kWh/m3 if an exit dye concentration of 4.65 mg/L is accepted. It can be concluded from this work that this method combines all of the advantages of the activated-carbon adsorption and electrolytic methods for the removal of dyes from wastewater.

  11. Tc-99 Adsorption on Selected Activated Carbons - Batch Testing Results

    SciTech Connect

    Mattigod, Shas V.; Wellman, Dawn M.; Golovich, Elizabeth C.; Cordova, Elsa A.; Smith, Ronald M.

    2010-12-01

    CH2M HILL Plateau Remediation Company (CHPRC) is currently developing a 200-West Area groundwater pump-and-treat system as the remedial action selected under the Comprehensive Environmental Response, Compensation, and Liability Act Record of Decision for Operable Unit (OU) 200-ZP-1. This report documents the results of treatability tests Pacific Northwest National Laboratory researchers conducted to quantify the ability of selected activated carbon products (or carbons) to adsorb technetium-99 (Tc-99) from 200-West Area groundwater. The Tc-99 adsorption performance of seven activated carbons (J177601 Calgon Fitrasorb 400, J177606 Siemens AC1230AWC, J177609 Carbon Resources CR-1240-AW, J177611 General Carbon GC20X50, J177612 Norit GAC830, J177613 Norit GAC830, and J177617 Nucon LW1230) were evaluated using water from well 299-W19-36. Four of the best performing carbons (J177606 Siemens AC1230AWC, J177609 Carbon Resources CR-1240-AW, J177611 General Carbon GC20X50, and J177613 Norit GAC830) were selected for batch isotherm testing. The batch isotherm tests on four of the selected carbons indicated that under lower nitrate concentration conditions (382 mg/L), Kd values ranged from 6,000 to 20,000 mL/g. In comparison. Under higher nitrate (750 mg/L) conditions, there was a measureable decrease in Tc-99 adsorption with Kd values ranging from 3,000 to 7,000 mL/g. The adsorption data fit both the Langmuir and the Freundlich equations. Supplemental tests were conducted using the two carbons that demonstrated the highest adsorption capacity to resolve the issue of the best fit isotherm. These tests indicated that Langmuir isotherms provided the best fit for Tc-99 adsorption under low nitrate concentration conditions. At the design basis concentration of Tc 0.865 µg/L(14,700 pCi/L), the predicted Kd values from using Langmuir isotherm constants were 5,980 mL/g and 6,870 mL/g for for the two carbons. These Kd values did not meet the target Kd value of 9,000 mL/g. Tests

  12. Pore structure of the activated coconut shell charcoal carbon

    NASA Astrophysics Data System (ADS)

    Budi, E.; Nasbey, H.; Yuniarti, B. D. P.; Nurmayatri, Y.; Fahdiana, J.; Budi, A. S.

    2014-09-01

    The development of activated carbon from coconut shell charcoal has been investigated by using physical method to determine the influence of activation parameters in term of temperature, argon gas pressure and time period on the pore structure of the activated carbon. The coconut shell charcoal was produced by pyrolisis process at temperature of about 75 - 150 °C for 6 hours. The charcoal was activated at various temperature (532, 700 and 868 °C), argon gas pressure (6.59, 15 and 23.4 kgf/cm2) and time period of (10, 60 and 120 minutes). The results showed that the pores size were reduced and distributed uniformly as the activation parameters are increased.

  13. Production Scale-Up or Activated Carbons for Ultracapacitors

    SciTech Connect

    Dr. Steven D. Dietz

    2007-01-10

    Transportation use accounts for 67% of the petroleum consumption in the US. Electric and hybrid vehicles are promising technologies for decreasing our dependence on petroleum, and this is the objective of the FreedomCAR & Vehicle Technologies Program. Inexpensive and efficient energy storage devices are needed for electric and hybrid vehicle to be economically viable, and ultracapacitors are a leading energy storage technology being investigated by the FreedomCAR program. The most important parameter in determining the power and energy density of a carbon-based ultracapacitor is the amount of surface area accessible to the electrolyte, which is primarily determined by the pore size distribution. The major problems with current carbons are that their pore size distribution is not optimized for liquid electrolytes and the best carbons are very expensive. TDA Research, Inc. (TDA) has developed methods to prepare porous carbons with tunable pore size distributions from inexpensive carbohydrate based precursors. The use of low-cost feedstocks and processing steps greatly lowers the production costs. During this project with the assistance of Maxwell Technologies, we found that an impurity was limiting the performance of our carbon and the major impurity found was sulfur. A new carbon with low sulfur content was made and found that the performance of the carbon was greatly improved. We also scaled-up the process to pre-production levels and we are currently able to produce 0.25 tons/year of activated carbon. We could easily double this amount by purchasing a second rotary kiln. More importantly, we are working with MeadWestvaco on a Joint Development Agreement to scale-up the process to produce hundreds of tons of high quality, inexpensive carbon per year based on our processes.

  14. Effects of organic carbon sequestration strategies on soil enzymatic activities

    NASA Astrophysics Data System (ADS)

    Puglisi, E.; Suciu, N.; Botteri, L.; Ferrari, T.; Coppolecchia, D.; Trevisan, M.; Piccolo, A.

    2009-04-01

    Greenhouse gases emissions can be counterbalanced with proper agronomical strategies aimed at sequestering carbon in soils. These strategies must be tested not only for their ability in reducing carbon dioxide emissions, but also for their impact on soil quality: enzymatic activities are related to main soil ecological quality, and can be used as early and sensitive indicators of alteration events. Three different strategies for soil carbon sequestration were studied: minimum tillage, protection of biodegradable organic fraction by compost amendment and oxidative polimerization of soil organic matter catalyzed by biometic porfirins. All strategies were compared with a traditional agricultural management based on tillage and mineral fertilization. Experiments were carried out in three Italian soils from different pedo-climatic regions located respectively in Piacenza, Turin and Naples and cultivated with maize or wheat. Soil samples were taken for three consecutive years after harvest and analyzed for their content in phosphates, ß-glucosidase, urease and invertase. An alteration index based on these enzymatic activities levels was applied as well. The biomimetic porfirin application didn't cause changes in enzymatic activities compared to the control at any treatment or location. Enzymatic activities were generally higher in the minimum tillage and compost treatment, while differences between location and date of samplings were limited. Application of the soil alteration index based on enzymatic activities showed that soils treated with compost or subjected to minimum tillage generally have a higher biological quality. The work confirms the environmental sustainability of the carbon sequestering agronomical practices studied.

  15. [Preparation and optimum process of walnut peel activated carbon by zinc chloride as activating agent].

    PubMed

    Liu, Xiao-hong; Wang, Xing-wei; Zhao, Bo; Lü, Jun-fang; Kang, Ni-na; Zhang, Yao-jun

    2014-12-01

    Walnut peel as raw material, zinc chloride was used as activating agent for preparation walnut peel activated carbon in the muffle furnace in this experiment, using orthogonal design. Yield, the specific surface area and iodine number of walnut peel activated carbon were determined at all designed experimental conditions and the optimum technological condition of preparation was obtained. By analysis of aperture, infrared spectra and the content of acidic group in surface with Boehm, walnut peel activated carbon of prepared at the optimum condition was characterized. The results showed the optimum technological parameters of preparation: activation temperature (600 °C), activation time (1 h), the concentration of zinc chloride (50%), the particle size (60 mesh). The specific surface area of walnut peel activated carbon obtained at optimum condition was mounting to 1258.05 m2 · g(-1), the ratio of medium porous 32.18%. Therefore, walnut peel can be used in the preparation of the high-quality activated carbon of large surface area. Agricultural wastes, as walnut peel, not only were implemented recycle, but also didn't make any pollution. Meanwhile, a cheap adsorbent was provided and it was of great significance to open a new source of activated carbon.

  16. [Preparation and optimum process of walnut peel activated carbon by zinc chloride as activating agent].

    PubMed

    Liu, Xiao-hong; Wang, Xing-wei; Zhao, Bo; Lü, Jun-fang; Kang, Ni-na; Zhang, Yao-jun

    2014-12-01

    Walnut peel as raw material, zinc chloride was used as activating agent for preparation walnut peel activated carbon in the muffle furnace in this experiment, using orthogonal design. Yield, the specific surface area and iodine number of walnut peel activated carbon were determined at all designed experimental conditions and the optimum technological condition of preparation was obtained. By analysis of aperture, infrared spectra and the content of acidic group in surface with Boehm, walnut peel activated carbon of prepared at the optimum condition was characterized. The results showed the optimum technological parameters of preparation: activation temperature (600 °C), activation time (1 h), the concentration of zinc chloride (50%), the particle size (60 mesh). The specific surface area of walnut peel activated carbon obtained at optimum condition was mounting to 1258.05 m2 · g(-1), the ratio of medium porous 32.18%. Therefore, walnut peel can be used in the preparation of the high-quality activated carbon of large surface area. Agricultural wastes, as walnut peel, not only were implemented recycle, but also didn't make any pollution. Meanwhile, a cheap adsorbent was provided and it was of great significance to open a new source of activated carbon. PMID:25881437

  17. The Impact of Ozone Treatment in Dynamic Bed Parameters on Changes in Biologically Active Substances of Juniper Berries

    PubMed Central

    Brodowska, Agnieszka Joanna; Śmigielski, Krzysztof; Nowak, Agnieszka; Czyżowska, Agata; Otlewska, Anna

    2015-01-01

    The development of the parameters of ozone decontamination method assuring the least possible losses of biologically active substances (essential oils and polyphenols) and their activity in common juniper (Juniperus communis (L.)) berries was studied. Ozone treatment in dynamic bed was conducted 9 times. The process was conducted under different ozone concentrations (100.0; 130.0; 160.0 g O3/m3) and times (30, 60, 90 min). After each decontamination, the microbiological profile of the juniper berries was studied, and the contaminating microflora was identified. Next to the microbiological profile, the phenolic profile, as well as antioxidant activity of extracts and essential oils were determined. The total polyphenol content (TPC), composition of essential oils, free radical-scavenging capacity, total antioxidant capacity, ferric-reducing antioxidant power (FRAP), beta-carotene bleaching test (BCB) and LC-MS polyphenol analysis were carried out. The study reveals that during short ozone contact times, higher amounts of TPC, 15.47 and 12.91 mg CE/g of extract, for samples 100/30 and 130/30, respectively, were demonstrated. Whereas samples 100/60, 130/60, 100/90, and 160/90 exhibited the lowest amount of phenolics. The highest antioxidant activity was found in the methanol extract obtained from ozonated berries which exhibited the lowest IC50 in all the antioxidant assays, such as DPPH, FRAP, and BCB assays. Ozone treatment showed noteworthy potential and its usage in food manufacturing and as an alternative decontamination method should be considered. PMID:26659905

  18. Synthesis and characterization of activated carbon from asphalt

    NASA Astrophysics Data System (ADS)

    Kandah, Munther Issa; Shawabkeh, Reyad; Al-Zboon, Mahmoud Ar'ef

    2006-11-01

    Asphalt (cheap and available in huge amount in Jordan) was converted into activated carbon powder by chemical treatment with sulphuric and nitric acids at 450 °C. The final product was characterized and found effective as adsorbent material. Its cation exchange capacity reaches 191.2 meq/100-g carbons when treated with 30 wt% acid/asphalt ratio without airflow rate injection and 208 meq/100-g carbons when 6.5 ml air/min was injected into the surface of the asphalt during activation at the same acid/asphalt weight ratio of 30 and temperature 450 °C. The zero point of charge for this product was found to be stable at pH value around 3 in the range of initial pH between 3 and 10.

  19. Mutual interactions of Pleurotus ostreatus with bacteria of activated sludge in solid-bed bioreactors.

    PubMed

    Svobodová, Kateřina; Petráčková, Denisa; Kozická, Barbora; Halada, Petr; Novotný, Čeněk

    2016-06-01

    White rot fungi are well known for their ability to degrade xenobiotics in pure cultures but few studies focus on their performance under bacterial stress in real wastewaters. This study investigated mutual interactions in co-cultures of Pleurotus ostreatus and activated sludge microbes in batch reactors and different culture media. Under the bacterial stress an increase in the dye decolorization efficiency (95 vs. 77.1 %) and a 2-fold elevated laccase activity (156.7 vs. 78.4 Ul(-1)) were observed in fungal-bacterial cultures compared to pure P. ostreatus despite a limited growth of bacteria in mixed cultures. According to 16S-rDNA analyses, P. ostreatus was able to alter the structure of bacterial communities. In malt extract-glucose medium the fungus inhibited growth of planktonic bacteria and prevented shifts in bacterial utilization of potential C-sources. A model bacterium, Rhodococcus erythropolis responded to fungal metabolites by down regulation of uridylate kinase and acetyl-CoA synthetase. PMID:27116960

  20. Activity of catalase adsorbed to carbon nanotubes: effects of carbon nanotube surface properties.

    PubMed

    Zhang, Chengdong; Luo, Shuiming; Chen, Wei

    2013-09-15

    Nanomaterials have been studied widely as the supporting materials for enzyme immobilization. However, the interactions between enzymes and carbon nanotubes (CNT) with different morphologies and surface functionalities may vary, hence influencing activities of the immobilized enzyme. To date how the adsorption mechanisms affect the activities of immobilized enzyme is not well understood. In this study the adsorption of catalase (CAT) on pristine single-walled carbon nanotubes (SWNT), oxidized single-walled carbon nanotubes (O-SWNT), and multi-walled carbon nanotubes (MWNT) was investigated. The adsorbed enzyme activities decreased in the order of O-SWNT>SWNT>MWNT. Fourier transforms infrared spectroscopy (FTIR) and circular dichrois (CD) analyses reveal more significant loss of α-helix and β-sheet of MWNT-adsorbed than SWNT-adsorbed CAT. The difference in enzyme activities between MWNT-adsorbed and SWNT-adsorbed CAT indicates that the curvature of surface plays an important role in the activity of immobilized enzyme. Interestingly, an increase of β-sheet content was observed for CAT adsorbed to O-SWNT. This is likely because as opposed to SWNT and MWNT, O-SWNT binds CAT largely via hydrogen bonding and such interaction allows the CAT molecule to maintain the rigidity of enzyme structure and thus the biological function.

  1. 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.

  2. Effects of aquifer storage and recovery activities on water quality in the Little Arkansas River and Equus Beds Aquifer, south-central Kansas, 2011-14

    USGS Publications Warehouse

    Stone, Mandy L.; Garrett, Jessica D.; Poulton, Barry C.; Ziegler, Andrew C.

    2016-07-18

    maximum contaminant level to a post recharge nonexceedance. Shallow groundwater chemical concentrations or rates of detection increased after artificial recharge began for the ions potassium, chloride, and fluoride; phosphorus and organic carbon species; trace elements barium, manganese, nickel, arsenate, arsenic, and boron; agricultural pesticides atrazine, metolachlor, metribuzin, and simazine; organic disinfection byproducts bromodichloromethane and trichloromethane; and gross beta levels. Additionally, water temperature, and pH were larger after recharge began; and total solids and slime-forming bacteria concentrations and densities were smaller. Total solids, nitrate, and selenium significantly decreased; and potassium, chloride, nickel, arsenic, fluoride, phosphorus and carbon species, and gross beta levels significantly increased in shallow groundwater after artificial recharge. Results of biological activity reaction tests indicated that water quality microbiology was different before and after artificial recharge began; at times, these differences may lead to changes in dominant bacterial populations that, in turn, may lead to formation and expansion in populations that may cause bioplugging and other unwanted effects. Calcite, iron (II) hydroxide, hydroxyapatite, and similar minerals, had shifts in saturation indices that generally were from undersaturation toward equilibrium and, in some cases, toward oversaturation. These shifts toward neutral saturation indices might suggest reduced weathering of the minerals present in the Equus Beds aquifer. Chemical weathering in the shallow parts of the aquifer may be accelerated because of the increased water temperatures and the system is more vulnerable to clogged pores and mineral dissolution as the equilibrium state is affected by recharge and withdrawal. When oversaturation is indicated for iron minerals, plugging of aquifer materials may happen.

  3. 40 CFR 60.1820 - How do I monitor the injection rate of activated carbon?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... activated carbon? 60.1820 Section 60.1820 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... activated carbon? If your municipal waste combustion unit uses activated carbon to control dioxins/furans or mercury emissions, you must meet three requirements: (a) Select a carbon injection system...

  4. Overview of EPA activities and research related to black carbon

    EPA Science Inventory

    The purpose of this international presentation is to give an overview of EPA activities related to black carbon (BC). This overview includes some summary information on how EPA defines BC, current knowledge on United States emissions and forecasted emission reductions, and ongoin...

  5. Preparation and characterization of activated carbon from demineralized tyre char

    NASA Astrophysics Data System (ADS)

    Manocha, S.; Prasad, Guddu R.; Joshi, Parth.; Zala, Ranjitsingh S.; Gokhale, Siddharth S.; Manocha, L. M.

    2013-06-01

    Activated carbon is the most adsorbing material for industrial waste water treatment. For wider applications, the main consideration is to manufacture activated carbon from low cost precursors, which are easily available and cost effective. One such source is scrap tyres. Recently much effort has been devoted to the thermal degradation of tyres into gaseous and liquid hydrocarbons and solid char residue, all of which have the potential to be processed into valuable products. As for solid residue, char can be used either as low-grade reinforcing filler or as activated carbon. The product recovered by a typical pyrolysis of tyres are usually, 33-38 wt% pyrolytic char, 38-55 wt% oil and 10-30 wt% solid fractions. In the present work activated carbon was prepared from pyrolyzed tyre char (PC). Demineralization involves the dissolution of metal into acids i.e. HCl, HNO3 and H2SO4 and in base i.e. NaOH. Different concentration of acid and base were used. Sodium hydroxide showed maximum amount of metal oxide removal. Further the concentration of sodium hydroxide was varied from 1N to 6N. As the concentration of acid are increased demineralization increases. 6N Sodium hydroxide is found to be more effective demineralising agent of tyre char.

  6. Activated carbon injection - a mercury control success story

    SciTech Connect

    2008-07-01

    Almost 100 full-scale activated carbon injection (ACI) systems have been ordered by US electric utilities. These systems have the potential to remove over 90% of the mercury in flue, at a cost below $10,000 per pound of mercury removal. Field trials of ACI systems arm outlined. 1 fig.

  7. Acoustical Evaluation of Carbonized and Activated Cotton Nonwovens

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An activated carbon fiber nonwoven (ACF) was manufactured from cotton nonowoven fabric. For the ACF acoustical application, a nonwoven composite of ACF with cotton nonwoven as a base layer was developed. Also produced were the composites of the cotton nonwoven base layer with a layer of glass fiber ...

  8. 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. PMID:26141882

  9. 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.

  10. Activation and micropore structure of carbon-fiber composites

    SciTech Connect

    Jagtoyen, M.; Derbyshire, F.; Kimber, G.

    1997-12-01

    Rigid, high surface area activated carbon fiber composites have been produced with high permeabilities for environmental applications in gas and water purification. The project involves a collaboration between the Oak Ridge National Laboratory (ORNL) and the Center for Applied Energy Research (CAER), University of Kentucky. The main focus of recent work has been to find a satisfactory means to uniformly activate large samples of carbon fiber composites to produce controlled pore structures. Processes have been developed using activation in steam and CO{sub 2}, and a less conventional method involving oxygen chemisorption and subsequent heat treatment. Another objective has been to explore applications for the activated composites in environmental applications related to fossil energy production.

  11. Petroleum pollutants in surface and groundwater as indicated by the carbon-14 activity of dissolved organic carbon.

    PubMed

    Spiker, E C; Rubin, M

    1975-01-10

    The (14)C activity of dissolved organic carbon (DOC) can be used to distinguish between the fossil organic carbon due to petrochemical effluents and modern organic carbon due to domestic wastes and natural decaying organic matter. Rivers polluted by petrochemical effluents show varying amounts of depression of the DOC (14)C activity, reflecting concentrations of (14)C-deficient fossil carbon of as much as about 40 percent of the total DOC.

  12. Characteristics of activated carbon and carbon nanotubes as adsorbents to remove annatto (norbixin) in cheese whey.

    PubMed

    Zhang, Yue; Pan, Kang; Zhong, Qixin

    2013-09-25

    Removing annatto from cheese whey without bleaching has potential to improve whey protein quality. In this work, the potential of two activated carbon products and multiwalled carbon nanotubes (CNT) was studied for extracting annatto (norbixin) in aqueous solutions. Batch adsorption experiments were studied for the effects of solution pH, adsorbent mass, contact duration, and ionic strength. The equilibrium adsorption data were observed to fit both Langmuir and Freundlich isotherm models. The thermodynamic parameters estimated from adsorption isotherms demonstrated that the adsorption of norbixin on three adsorbents is exothermic, and the entropic contribution differs with adsorbent structure. The adsorption kinetics, with CNT showing a higher rate than activated carbon, followed the pseudo first order and second order rate expressions and demonstrated the significance of intraparticle diffusion. Electrostatic interactions were observed to be significant in the adsorption. The established adsorption parameters may be used in the dairy industry to decolorize cheese whey without applying bleaching agents.

  13. The Local Complement Activation on Vascular Bed of Patients with Systemic Sclerosis: A Hypothesis-Generating Study

    PubMed Central

    Scambi, Cinzia; Ugolini, Sara; Jokiranta, T. Sakari; De Franceschi, Lucia; Bortolami, Oscar; La Verde, Valentina; Guarini, Patrizia; Caramaschi, Paola; Ravagnani, Viviana; Martignoni, Guido; Colato, Chiara; Pedron, Serena; Benedetti, Fabio; Sorio, Marco; Poli, Fabio; Biasi, Domenico

    2015-01-01

    Objective The role of complement system in the pathogenesis of systemic sclerosis (SSc) has been debated during the last decade but an evident implication in this disease has never been found. We carried out an explorative study on SSc patients to evaluate the expression of soluble and local C5b-9 complement complex and its relation with a complement regulator, the Membrane Cofactor Protein (MCP, CD46) on skin vascular bed as target distinctive of SSc disease. We also analyzed two polymorphic variants in the complement activation gene cluster involving the MCP region. Methods C5b-9 plasma levels of SSc patients and healthy subjects were analyzed by ELISA assay. Archival skin biopsies of SSc patients and controls were subjected to immunofluorescence analysis to detect C5b-9 and MCP on vascular endothelial cells. The expression of MCP was validated by immunoblot analysis with specific antibody. Polymorphic variants in the MCP gene promoter were tested by a quantitative PCR technique-based allelic discrimination method. Results Even though circulating levels of C5b-9 did not differ between SSc and controls, C5b-9 deposition was detected in skin biopsies of SSc patients but not in healthy subjects. MCP was significantly lower in skin vessels of SSc patients than in healthy controls and was associated with the over-expression of two polymorphic variants in the MCP gene promoter, which has been related to more aggressive phenotypes in other immune-mediated diseases. Conclusions Our results firsty document the local complement activation with an abnormal expression of MCP in skin vessels of SSc patients, suggesting that a subset of SSc patients might be exposed to more severe organ complications and clinical evolution due to abnormal local complement activation. PMID:25658605

  14. Effects on the efficiency of activated carbon on exposure to welding fumes

    SciTech Connect

    Ghosh, D.

    1995-02-01

    It is the intention of this paper to document that certain types of welding fumes have little or no effect on the effectiveness of the carbon filter air filtration efficiency when directly exposed to a controlled amount of welding fumes for a short-term period. The welding processes studied were restricted to shielded metal arc welding (SMAW), flux cored arc welding (FCAW), gas tungsten arc welding (GTAW) and gas metal arc welding (GMAW) processes. Contrary to the SMAW and FCAW processes, the GTAW (or TIG) and the GMAW (or MIG) welding processes do not require the use of flux as part of the overall process. Credit was taken for these processes occurring in inert gas environments and producing minimal amount of smoke. It was concluded that a study involving the SMAW process would also envelop the effects of the TIG and MIG welding processes. The quantity of welding fumes generated during the arc welding process is a function of the particular process, the size and type of electrode, welding machine amperage, and operator proficiency. For this study, the amount of welding for specific testing was equated to the amount of welding normally conducted during plant unit outages. Different welding electrodes were also evaluated, and the subsequent testing was limited to an E7018 electrode which was judged to be representative of all carbon and stainless steel electrodes commonly used at the site. The effect of welding fumes on activated charcoal was tested using a filtration unit complete with prefilters, upstream and downstream high efficiency particulate air (HEPA) filters, and a carbon adsorber section. The complete system was field tested in accordance with ANSI N510 standards prior to exposing the filters and the adsorber bed to welding fumes. The carbon samples were tested at an established laboratory using ASTM D3803-1989 standards.

  15. Adsorption and desorption of noble gases on activated charcoal: I. 133Xe studies in a monolayer and packed bed.

    PubMed

    Scarpitta, S C; Harley, N H

    1990-10-01

    Detailed desorption studies using petroleum-based activated charcoals were conducted in monolayers and packed beds. Less extensive studies were conducted on several other types of charcoal. Kinetic studies, using 133Xe, demonstrated the existence of a micropore volume with entrance capillaries that together determined the response characteristics of charcoal to external concentration gradients of tracer gases. This new two-phase model, composed of micropores and entrance capillaries, describes the desorption dynamics of an adsorbed gas in the presence of water vapor. Condensed water vapor in the entrance capillaries of the charcoal reduced the effective pore radius and increased the diffusion half-time. Water could also adversely affect the integrating capability of the charcoal dramatically if the adsorbed water completely blocked the entrance capillaries. The amount of adsorbed water required to block the capillaries varied with the charcoal type and was termed here as the "break-point." The desorption parameters measured in this work can be used to design an improved passive Rn monitor to effectively integrate during a 3-7 d exposure period by eliminating the adverse effects of water vapor. The improved canister design would provide more accurate and reproducible measurements of indoor Rn concentrations than are currently available. PMID:2398007

  16. Determining water content in activated carbon for double-layer capacitor electrodes

    NASA Astrophysics Data System (ADS)

    Egashira, Minato; Izumi, Takuma; Yoshimoto, Nobuko; Morita, Masayuki

    2016-09-01

    Karl-Fisher titration is used to estimate water contents in activated carbon and the distribution of impurity-level water in an activated carbon-solvent system. Normalization of the water content of activated carbon is attempted using vacuum drying after immersion in water was controlled. Although vacuum drying at 473 K and 24 h can remove large amounts of water, a substantial amount of water remains in the activated carbon. The water release to propylene carbonate is less than that to acetonitrile. The degradation of capacitor cell capacitance for activated carbon with some amount of water differs according to the electrolyte solvent type: acetonitrile promotes greater degradation than propylene carbonate does.

  17. Esterase activity of carbonic anhydrases serves as surrogate for selecting antibodies blocking hydratase activity.

    PubMed

    Uda, Narasimha Rao; Seibert, Volker; Stenner-Liewen, Frank; Müller, Philipp; Herzig, Petra; Gondi, Gabor; Zeidler, Reinhard; van Dijk, Marc; Zippelius, Alfred; Renner, Christoph

    2015-12-01

    Carbonic anhydrase 9 (CA9) and carbonic anhydrase 12 (CA12) were proposed as potential targets for cancer therapy more than 20 years ago. However, to date, there are only very few antibodies that have been described to specifically target CA9 and CA12 and also block the enzymatic activity of their targets. One of the early stage bottlenecks in identifying CA9- and CA12-inhibiting antibodies has been the lack of a high-throughput screening system that would allow for rapid assessment of inhibition of the targeted carbon dioxide hydratase activity of carbonic anhydrases. In this study, we show that measuring the esterase activity of carbonic anhydrase offers a robust and inexpensive screening method for identifying antibody candidates that block both hydratase and esterase activities of carbonic anhydrase's. To our knowledge, this is the first implementation of a facile surrogate-screening assay to identify potential therapeutic antibodies that block the clinically relevant hydratase activity of carbonic anhydrases. PMID:25775095

  18. 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. PMID:22370231

  19. 40 CFR 62.15275 - How do I monitor the injection rate of activated carbon?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... carbon? If your municipal waste combustion unit uses activated carbon to control dioxins/furans or... dioxins/furans and mercury stack test, determine the average carbon feed rate in kilograms (or pounds)...

  20. Waste polyvinylchloride derived pitch as a precursor to develop carbon fibers and activated carbon fibers.

    PubMed

    Qiao, W M; Yoon, S H; Mochida, I; Yang, J H

    2007-01-01

    Polyvinylchloride (PVC) was successfully recycled through the solvent extraction from waste pipe with an extraction yield of ca. 86%. The extracted PVC was pyrolyzed by a two-stage process (260 and 410 degrees C) to obtain free-chlorine PVC based pitch through an effective removal of chlorine from PVC during the heat-treatment. As-prepared pitch (softening point: 220 degrees C) was spun, stabilized, carbonized into carbon fibers (CFs), and further activated into activated carbon fibers (ACFs) in a flow of CO2. As-prepared CFs show comparable mechanical properties to commercial CFs, whose maximum tensile strength and modulus are 862 MPa and 62 GPa, respectively. The resultant ACFs exhibit a high surface area of 1200 m2/g, narrow pore size distribution and a low oxygen content of 3%. The study provides an effective insight to recycle PVC from waste PVC and develop a carbon precursor for high performance carbon materials such as CFs and ACFs. PMID:17157493

  1. Removing 17β-estradiol from drinking water in a biologically active carbon (BAC) reactor modified from a granular activated carbon (GAC) reactor.

    PubMed

    Li, Zhongtian; Dvorak, Bruce; Li, Xu

    2012-06-01

    Estrogenic compounds in drinking water sources pose potential threats to human health. Treatment technologies are needed to effectively remove these compounds for the production of safe drinking water. In this study, GAC adsorption was first tested for its ability to remove a model estrogenic compound, 17β-estradiol (E2). Although GAC showed a relatively high adsorption capacity for E2 in isotherm experiments, it appeared to have a long mass transfer zone in a GAC column reactor, causing an early leakage of E2 in the effluent. With an influent E2 concentration of 20 μg/L, the GAC reactor was able to bring down effluent E2 to ≈ 200 ng/L. To further enhance E2 removal, the GAC reactor was converted to a biologically active carbon (BAC) reactor by promoting biofilm growth in the reactor. Under optimal operating conditions, the BAC reactor had an effluent E2 concentration of ≈ 50 ng/L. With the empty bed contact times tested, the reactor exhibited more robust E2 removal performance under the BAC operation than under the GAC operation. It is noted that estrone (E1), an E2 biodegradation intermediate, was frequently detected in reactor effluent during the BAC operation. Results from this study suggested that BAC could be an effective drinking water treatment process for E2 removal and in the meantime E1 accumulation needs to be addressed.

  2. Simultaneous removal of chromate and nitrate in a packed-bed bioreactor using biodegradable meal box as carbon source and biofilm carriers.

    PubMed

    Li, Jie; Jin, Ruofei; Liu, Guangfei; Tian, Tian; Wang, Jing; Zhou, Jiti

    2016-05-01

    An up-flow packed-bed bioreactor was constructed to investigate the simultaneous removal of chromate and nitrate using biodegradable meal box as carbon source and biofilm carriers. The bioreactor was operated for 164days with varying influent Cr(VI) concentrations (2.0-50.0mg/L) and hydraulic retention times (HRT, 10-24h). It was shown that complete denitrification and Cr(VI) reduction could be achieved when influent Cr(VI) concentrations were lower than 20mg/L with a HRT of 17h. Shortening the HRT could significantly reduce the effluent CODcr. It was also observed that Cr(III) was mainly immobilized on the biofilm. Further investigation on Cr distribution in the biofilm compartments indicated that Cr(VI) reduction occurred in all compartments and the intercellular Cr was dominant. High-throughput sequencing analysis showed that Proteobacteria, Bacteroidetes and Firmicutes were the dominant phyla in the biofilm and Cr(VI) stress had a negative effect on the abundance of most bacteria. PMID:26896715

  3. PERFORMANCE OF ACTIVATED SLUDGE-POWDERED ACTIVATED CARBON-WET AIR REGENERATION SYSTEMS

    EPA Science Inventory

    The investigation summarized in the report was undertaken to evaluate the performance of powdered activated carbon (PAC) technology used in conjunction with wet air regeneration (WAR) at municipal wastewater treatment plants. Excessive ash concentrations accumulated in the mixed ...

  4. Modeling trapping mechanism for PCB adsorption on activated carbon

    NASA Astrophysics Data System (ADS)

    Jensen, Bjørnar; Kvamme, Bjørn; Kuznetsova, Tatyana; Oterhals, A.˚ge

    2012-12-01

    The levels of polychlorinated dibenzo-p-dioxin, polychlorinated dibenzofuran (PCDD/F) and dioxin-like polychlorinated biphenyl (DL-PCB) in fishmeal and fish oil produced for use in feed for salmon is above present European legislation levels in some regions of the world and different decontamination approaches have been proposed [1]. One of these is adsorption on activated carbon. This approach appears to be efficient for adsorption of PCDD/F but less efficient for DL-PCB [2]. Activated carbon consists of slit pores with average sizes of 20 - 50 Ångstroms. One hypothesis [2] for the mechanism of trapping DL-PCB is reduced ability for intramolecular movements of the PCB molecules inside the slit pores. In order to investigate this hypothesis we have used quantum mechanics [3] to characterize two DL-PCB congeners, respectively congener 77 (3,3',4,4'-Tetrachlorobiphenyl) and congener 118 (2,3',4,4',5-Pentachlorobiphenyl) and Triolein (18:1) [4] as a major constituent of the solvent fish oil. A model for activated carbon was constructed using a crystal structure of graphite from the American Mineralogist Crystal Structure Database [5]. The crystal structure used was originally from Wyckoff [6]. A small program had to be written to generate the desired graphite structure as it contains no less than 31232 Carbon atoms. Partial atomic charges were estimated using QM with DFT/B3LYP/6-311+g** and SM6 [7].

  5. Preloading hydrous ferric oxide into granular activated carbon for arsenic removal.

    PubMed

    Jang, Min; Chen, Weifang; Cannon, Fred S

    2008-05-01

    Arsenic is of concern in water treatment because of its health effects. This research focused on incorporating hydrous ferric oxide (HFO) into granular activated carbon (GAC) for the purpose of arsenic removal. Iron was incorporated into GAC via incipient wetness impregnation and cured at temperatures ranging from 60 to 90 degrees C. X-ray diffractions and arsenic sorption as a function of pH were conducted to investigate the effect of temperature on final iron oxide (hydroxide) and their arsenic removal capabilities. Results revealed that when curing at 60 degrees C, the procedure successfully created HFO in the pores of GAC, whereas at temperatures of 80 and 90 degrees C, the impregnated iron oxide manifested a more crystalline form. In the column tests using synthetic water, the HFO-loaded GAC prepared at 60 degrees C also showed higher sorption capacities than media cured at higher temperatures. These results indicated that the adsorption capacity for arsenic was closely related to the form of iron (hydr)oxide for a given iron content For the column test using a natural groundwater, HFO-loaded GAC (Fe, 11.7%) showed an arsenic sorption capacity of 26 mg As/g when the influent contained 300 microg/L As. Thus, the preloading of HFO into a stable GAC media offered the opportunity to employ fixed carbon bed reactors in water treatment plants or point-of-use filters for arsenic removal. PMID:18522120

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

    PubMed

    Clack, Herek L

    2012-07-01

    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. PMID:22663136

  7. Formation of continuous activated carbon fibers for barrier fabrics

    NASA Astrophysics Data System (ADS)

    Liang, Ying

    1997-08-01

    Commercial protective suits made of active carbon granules or nonwoven fabrics are heavy, have low moisture vapor transport rate, and are uncomfortable. Inherent problems due to construction of barrier fabrics lead to severe heat stress when worn for even short time in warm environments. One proposed method to eliminate these problems is to facilitate the construction of a fabric made of continuous activated carbon fibers (CACF). This study is directed toward investigating the possibility of developing CAFC from two precursors: aramid and fibrillated PAN fiber. It was shown in this study that Kevlar-29 fibers could be quickly carbonized and activated to CACF with high adsorptivity and relatively low weight loss. CACF with high surface area (>500 msp2/g) and reasonable tenacity (≈1g/denier) were successfully prepared from Kevlar fibers through a three-step process: pretreatment, carbonization, and activation. X-ray diffraction, Fourier Transform Infrared Spectroscopy (FTIR), and thermal analysis were conducted to understand the evolution of physical and chemical properties during pretreatment. The influence of temperature, heating rate, and pyrolysis environment on the thermal behavior was determined by DSC and TGA/DTA and used as an indicator for optimizing the pyrolysis conditions. Surface analysis by nitrogen isotherms indicated that the resultant fibers had micropores and mesopores on the surface of CACF. This was also inferred by studies on the surface morphology through Scanning Electron Microscopy (SEM) and Scanning Tunneling Microscopy (STM). An investigation of the surface chemical structure by X-ray photoelectron spectroscopy (XPS) before and after activation and elemental analysis confirmed that adsorption of Kevlar based CACF mainly arises due to the physisorption instead of chemisorption. A multistep stabilization along with carbonization and activation was used to prepare active carbon fiber from fibrillated PAN fiber. The resultant fiber retained

  8. Nitric acid vapor removal by activated, impregnated carbons

    SciTech Connect

    Wood, G.O.

    1996-12-31

    Laboratory and industrial workers can be exposed to vapors of nitric acid, especially in accidents, such as spills. Nitric acid can also be a product of incineration for energy production or waste (e.g., CW agent) disposal. Activated carbons containing impregnants for enhancing vapor and gas removal have been tested for effectiveness in removing vapors of nitric acid from air. The nitric acid vapor was generated from concentrated acid solutions and detected by trapping in a water bubbler for pH measurements. Both low and moderate relative humidity conditions were used. All carbons were effective at vapor contact times representative of air-purifying respirator use. One surprising observation was the desorption of low levels of ammonia from impregnated carbons. This was apparently due to residual ammonia from the impregnation processes.

  9. Sorption of cobalt on activated carbons from aqueous solutions

    SciTech Connect

    Paajanen, A.; Lehto, J.; Santapakka, T.; Morneau, J.P.

    1997-01-01

    The efficiencies of 15 commercially available activated carbons were tested for the separation of trace cobalt ({sup 60}Co) in buffer solutions at pH 5.0, 6.7, and 9.1. On the basis of the results four carbon products, Diahope-006, Eurocarb TN5, Hydraffin DG47, and Norit ROW Supra, were selected for further study. These carbons represented varying (low, medium and high) cobalt removal efficiencies and were prepared of three typical raw materials: peat, coconut shell, or coal. Study was made of the effects on sorption efficiencies of factors of interest in metal/radionuclide-bearing waste effluents. These factors were pH, sodium ions, borate, and citrate.

  10. Structural characteristics of modified activated carbons and adsorption of explosives.

    PubMed

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

    2003-10-15

    Several series of activated carbons prepared by catalytic and noncatalytic gasification and subsequent deposition of pyrocarbon by pyrolysis of methylene chloride or n-amyl alcohol were studied by FTIR, chromatography, and adsorption methods using nitrogen and probe organics (explosives). The relationships between the textural characteristics of carbon samples and the recovery rates (eta) of explosives on solid-phase extraction (SPE) using different solvents for their elution after adsorption were analyzed using experimental and quantum chemical calculation results. The eta values for nitrate esters, cyclic nitroamines, and nitroaromatics only partially correlate with different adsorbent parameters (characterizing microporosity, mesoporosity, pore size distributions, etc.), polarity of eluting solvents, or characteristics of probe molecules, since there are many factors strongly affecting the recovery rates. Some of the synthesized carbons provide higher eta values than those for such commercial adsorbents as Hypercarb and Envicarb.

  11. Waste management activities and carbon emissions in Africa

    SciTech Connect

    Couth, R.; Trois, C.

    2011-01-15

    This paper summarizes research into waste management activities and carbon emissions from territories in sub-Saharan Africa with the main objective of quantifying emission reductions (ERs) that can be gained through viable improvements to waste management in Africa. It demonstrates that data on waste and carbon emissions is poor and generally inadequate for prediction models. The paper shows that the amount of waste produced and its composition are linked to national Gross Domestic Product (GDP). Waste production per person is around half that in developed countries with a mean around 230 kg/hd/yr. Sub-Saharan territories produce waste with a biogenic carbon content of around 56% (+/-25%), which is approximately 40% greater than developed countries. This waste is disposed in uncontrolled dumps that produce large amounts of methane gas. Greenhouse gas (GHG) emissions from waste will rise with increasing urbanization and can only be controlled through funding mechanisms from developed countries.

  12. Irreversible adsorption of phenolic compounds by activated carbons

    SciTech Connect

    Grant, T.M.; King, C.J.

    1988-12-01

    Studies were undertaken to determine the reasons why phenolic sorbates can be difficult to remove and recover from activated carbons. The chemical properties of the sorbate and the adsorbent surface, and the influences of changes in the adsorption and desorption conditions were investigated. Comparison of isotherms established after different contact times or at different temperatures indicated that phenolic compounds react on carbon surfaces. The reaction rate is a strong function of temperature. Regeneration of carbons by leaching with acetone recovered at least as much phenol as did regeneration with other solvents or with displacers. The physiochemical properties of adsorbents influences irreversible uptakes. Sorbates differed markedly in their tendencies to undergo irreversible adsorption. 64 refs., 47 figs., 32 tabs.

  13. Authigenic carbonates from active methane seeps offshore southwest Africa

    NASA Astrophysics Data System (ADS)

    Pierre, Catherine; Blanc-Valleron, Marie-Madeleine; Demange, Jérôme; Boudouma, Omar; Foucher, Jean-Paul; Pape, Thomas; Himmler, Tobias; Fekete, Noemi; Spiess, Volkhard

    2012-12-01

    The southwest African continental margin is well known for occurrences of active methane-rich fluid seeps associated with seafloor pockmarks at water depths ranging broadly from the shelf to the deep basins, as well as with high gas flares in the water column, gas hydrate accumulations, diagenetic carbonate crusts and highly diverse benthic faunal communities. During the M76/3a expedition of R/V METEOR in 2008, gravity cores recovered abundant authigenic carbonate concretions from three known pockmark sites—Hydrate Hole, Worm Hole, the Regab pockmark—and two sites newly discovered during that cruise, the so-called Deep Hole and Baboon Cluster. The carbonate concretions were commonly associated with seep-benthic macrofauna and occurred within sediments bearing shallow gas hydrates. This study presents selected results from a comprehensive analysis of the mineralogy and isotope geochemistry of diagenetic carbonates sampled at these five pockmark sites. The oxygen isotope stratigraphy obtained from three cores of 2-5 m length indicates a maximum age of about 60,000-80,000 years for these sediments. The authigenic carbonates comprise mostly magnesian calcite and aragonite, associated occasionally with dolomite. Their very low carbon isotopic compositions (-61.0 < δ13C ‰ V-PDB < -40.1) suggest anaerobic oxidation of methane (AOM) as the main process controlling carbonate precipitation. The oxygen isotopic signatures (+2.4 < δ18O ‰ V-PDB < +6.2) lie within the range in equilibrium under present-day/interglacial to glacial conditions of bottom seawater; alternatively, the most positive δ18O values might reflect the contribution of 18O-rich water from gas hydrate decomposition. The frequent occurrence of diagenetic gypsum crystals suggests that reduced sulphur (hydrogen sulphide, pyrite) from sub-seafloor sediments has been oxidized by oxygenated bottom water. The acidity released during this process can potentially induce the dissolution of carbonate, thereby

  14. Activated carbons obtained from sewage sludge by chemical activation: gas-phase environmental applications.

    PubMed

    Boualem, T; Debab, A; Martínez de Yuso, A; Izquierdo, M T

    2014-07-01

    The objective of this study was to evaluate the adsorption capacity for toluene and SO2 of low cost activated carbons prepared from sewage sludge by chemical activation at different impregnation ratios. Samples were characterized by proximate and ultimate analyses, thermogravimetry, infrared spectroscopy and N2 adsorption. Because of the low carbon content of the raw material, the development of porosity in the activated carbons was mainly of a mesoporous nature, with surface areas lower than 300 m(2)/g. The study of gas-phase applications for activated carbons from sewage sludge was carried out using both an organic and an inorganic compound in order to screen for possible applications. Toluene adsorption capacity at saturation was around 280 mg/g, which is a good level of performance given the high ash content of the activated carbons. However, dynamic experiments at low toluene concentration presented diffusion problems resulting from low porosity development. SO2 adsorption capacity is associated with average micropore size, which can be controlled by the impregnation ratio used to prepare the activated carbons.

  15. Preparation of activated carbons from macadamia nut shell and coconut shell by air activation

    SciTech Connect

    Tam, M.S.; Antal, M.J. Jr.

    1999-11-01

    A novel, three-step process for the production of high-quality activated carbons from macadamia nut shell and coconut shell charcoals is described. In this process the charcoal is (1) heated to a high temperature (carbonized), (2) oxidized in air following a stepwise heating program from low (ca. 450 K) to high (ca. 660 K) temperatures (oxygenated), and (3) heated again in an inert environment to a high temperature (activated). By use of this procedure, activated carbons with surface areas greater than 1,000 m{sub 2}/g are manufactured with an overall yield of 15% (based on the dry shell feed). Removal of carbon mass by the development of mesopores and macropores is largely responsible for increases in the surface area of the carbons above 600 m{sub 2}/g. Thus, the surface area per gram of activated carbon can be represented by an inverse function of the yield for burnoffs between 15 and 60%. These findings are supported by mass-transfer calculations and pore-size distribution measurements. A kinetic model for gasification of carbon by oxygen, which provides for an Eley-Rideal type reaction of a surface oxide with oxygen in air, fits the measured gasification rates reasonably well over the temperature range of 550--660 K.

  16. Characterization and metal sorptive properties of oxidized active carbon.

    PubMed

    Strelko, Vladimir; Malik, Danish J

    2002-06-01

    A commercial activated carbon Chemviron F 400 has been oxidized using nitric acid in order to introduce a variety of acidic surface functional groups. Both unoxidized and oxidized carbon samples were characterized using nitrogen porosimetry, elemental analysis, pH titration, Boehm's titration, and electrophoretic mobility measurements. Results show that oxidation treatment reduced surface area and pore volume. However, the carbon surface acquires an acidic character with carboxylic groups being the dominant surface functional groups. The modified sample displays cation-exchange properties over a wide range of pH values and exhibits polyfunctional nature. Both carbon samples were challenged for the removal of transition metals such as copper(II), nickel(II), cobalt(II), zinc(II), and manganese(II). The affinity series Mn2+Zn2+ has been found to coincide with the general stability sequence of metal complexes (the Irving-Williams series). The higher preference displayed by carbons toward copper(II) is a consequence of the fact that copper(II) often forms distorted and more stable octahedral complexes. PMID:16290653

  17. Enhancing capacitive deionization performance of electrospun activated carbon nanofibers by coupling with carbon nanotubes.

    PubMed

    Dong, Qiang; Wang, Gang; Wu, Tingting; Peng, Senpei; Qiu, Jieshan

    2015-05-15

    Capacitive deionization (CDI) is an alternative, effective and environmentally friendly technology for desalination of brackish water. The performance of the CDI device is highly determined by the electrode materials. In this paper, a composite of carbon nanotubes (CNTs) embedded in activated carbon nanofiber (ACF) was prepared by a direct co-electrospinning way and subsequent CO2 activation. The introduction of CNTs can greatly improve the conductivity while the CO2-mediated activation can render the final product with high porosity. As such, the hybrid structure can provide an excellent storage space and pathways for ion adsorption and conduction. When evaluated as electrode materials for CDI, the as-prepared CNT/ACF composites with higher electrical conductivity and mesopore ratios exhibited higher electrosorption capacity and good regeneration performance in comparison with the pure ACF.

  18. Nomex-derived activated carbon fibers as electrode materials in carbon based supercapacitors

    NASA Astrophysics Data System (ADS)

    Leitner, K.; Lerf, A.; Winter, M.; Besenhard, J. O.; Villar-Rodil, S.; Suárez-García, F.; Martínez-Alonso, A.; Tascón, J. M. D.

    Electrochemical characterization has been carried out for electrodes prepared of several activated carbon fiber samples derived from poly (m-phenylene isophthalamide) (Nomex) in an aqueous solution. Depending on the burn-off due to activation the BET surface area of the carbons was in the order of 1300-2800 m 2 g -1, providing an extensive network of micropores. Their capability as active material for supercapacitors was evaluated by using cyclic voltammetry and impedance spectroscopy. Values for the capacitance of 175 F g -1 in sulfuric acid were obtained. Further on, it was observed that the specific capacitance and the performance of the electrode increase significantly with increasing burn-off degree. We believe that this fact can be attributed to the increase of surface area and porosity with increasing burn-off.

  19. Understanding the fate of organic micropollutants in sand and granular activated carbon biofiltration systems.

    PubMed

    Paredes, L; Fernandez-Fontaina, E; Lema, J M; Omil, F; Carballa, M

    2016-05-01

    In this study, sand and granular activated carbon (GAC) biofilters were comparatively assessed as post-treatment technologies of secondary effluents, including the fate of 18 organic micropollutants (OMPs). To determine the contribution of adsorption and biotransformation in OMP removal, four reactors were operated (two biofilters (with biological activity) and two filters (without biological activity)). In addition, the influence of empty bed contact time (EBCT), ranging from 0.012 to 3.2d, and type of secondary effluent (anaerobic and aerobic) were evaluated. Organic matter, ammonium and nitrate were removed in both biofilters, being their adsorption higher on GAC than on sand. According to the behaviour exhibited, OMPs were classified in three different categories: I) biotransformation and high adsorption on GAC and sand (galaxolide, tonalide, celestolide and triclosan), II) biotransformation, high adsorption on GAC but low or null adsorption on sand (ibuprofen, naproxen, fluoxetine, erythromycin, roxythromycim, sulfamethoxazole, trimethoprim, bisphenol A, estrone, 17β-estradiol and 17α-ethinylestradiol), and, III) only adsorption on GAC (carbamazepine, diazepam and diclofenac). No influence of EBCT (in the range tested) and type of secondary effluent was observed in GAC reactors, whereas saturation and kinetic limitation of biotransformation were observed in sand reactors. Taking into account that most of the organic micropollutants studied (around 60%) fell into category II, biotransformation is crucial for the elimination of OMPs in sand biofilters. PMID:26897407

  20. Nitrogen-doped carbon nanotubes as a highly active metal-free catalyst for selective oxidation.

    PubMed

    Chizari, Kambiz; Deneuve, Adrien; Ersen, Ovidiu; Florea, Ileana; Liu, Yu; Edouard, David; Janowska, Izabela; Begin, Dominique; Pham-Huu, Cuong

    2012-01-01

    Catalytic reactions are generally carried out on supported metals or oxides, which act as an active phase and require impregnation and thermal treatment steps. During tests, the metal or oxide nanoparticles could be further sintered, which would induces deactivation. Direct incorporation of the active phase into the matrix of a support could be an elegant alternative to prevent catalyst deactivation. Here, we report that nitrogen-doped carbon nanotubes (N-CNTs) can be efficiently employed as a metal-free catalyst for oxidative reactions that allow the selective transformation of the harmful, gaseous H(2)S into solid sulfur. The catalyst exhibits a high stability during the test at high space velocity. The macroscopic shaping of the catalyst on the silicon carbide foam also increases its catalytic activity by improving the contact between the reactants and the catalyst. Such macroscopic shaping allows the avoidance of problems linked with transport and handling of nanoscopic materials and also reduces the pressure drop across the catalyst bed to a large extent.

  1. Production of charcoal and activated carbon at elevated pressure

    SciTech Connect

    Dai, Xiangfeng; Norberg, N.; Antal, M.J. Jr.

    1995-12-31

    With its wide range of properties, charcoal finds many commercial applications for domestic cooking, refining of metals (steel, copper, bronze, nickel, aluminum and electro-manganese), production of chemicals (carbon disulfide, calcium carbide, silicon carbide, sodium cyanide, carbon black, fireworks, gaseous chemicals, absorbents, soil conditioners and pharmaceuticals), as well as production of activated carbon and synthesis gas. In 1991, the world production of charcoal was 22.8 million cubic meters (3.8 million metric tons) as shown in Table 1. Brazil is the world`s largest charcoal producer --- 5.9 million cubic meters or one million metric tons was produced in 1991, most of which is used in steel and iron industry. African countries produced 45% of the world total amount of charcoal, where 86% of the wood-based energy is for domestic use, most of which is inefficiently used. Charcoal is produced commercially in kilns with a 25% to 30% yield by mass on a 7 to 12 day operating cycle. Until recently, the highest yield of good quality charcoal reported in the literature was 38%. In this paper, and ASME code rated experimental system is presented for producing charcoal and activated carbon from biomass.

  2. Synthesis and Antioxidant Activity of Hydroxytyrosol Alkyl-Carbonate Derivatives.

    PubMed

    Fernandez-Pastor, Ignacio; Fernandez-Hernandez, Antonia; Rivas, Francisco; Martinez, Antonio; Garcia-Granados, Andres; Parra, Andres

    2016-07-22

    Three procedures have been investigated for the isolation of tyrosol (1) and hydroxytyrosol (2) from a phenolic extract obtained from the solid residue of olive milling. These three methods, which facilitated the recovery of these phenols, were chemical or enzymatic acetylation, benzylation, and carbomethoxylation, and subsequent carbonylation or acetonation reactions. Several new lipophilic alkyl-carbonate derivatives of hydroxytyrosol have been synthesized, coupling the primary hydroxy group of this phenol, through a carbonate linker, using alcohols with different chain lengths. The antioxidant properties of these lipophilic derivatives have been evaluated by different methods and compared with free hydroxytyrosol (2) and also with the well-known antioxidants BHT and α-tocopherol. Three methods were used for the determination of this antioxidant activity: FRAP and ABTS assays, to test the antioxidant power in hydrophilic media, and the Rancimat test, to evaluate the antioxidant capacity in a lipophilic matrix. These new alkyl-carbonate derivatives of hydroxytyrosol enhanced the antioxidant activity of this natural phenol, with their antioxidant properties also being higher than those of the commercial antioxidants BHT and α-tocopherol. There was no clear influence of the side-chain length on the antioxidant properties of the alkyl-carbonate derivatives of 2, although the best results were achieved mainly by the compounds with a longer chain on the primary hydroxy group of this natural phenolic substance. PMID:27337069

  3. Bed Bugs FAQs

    MedlinePlus

    ... Tropical Diseases Laboratory Diagnostic Assistance [DPDx] Parasites Home Bed Bugs FAQs Recommend on Facebook Tweet Share Compartir On ... are bed bugs treated and prevented? What are bed bugs? Bed bugs ( Cimex lectularius ) are small, flat, parasitic ...

  4. Activated carbon from flash pyrolysis of eucalyptus residue.

    PubMed

    Grima-Olmedo, C; Ramírez-Gómez, Á; Gómez-Limón, D; Clemente-Jul, C

    2016-09-01

    Forestry waste (eucalyptus sp) was converted into activated carbon by initial flash pyrolysis followed carbonization and CO2 activation. These residues were obtained from a pilot plant in Spain that produces biofuel, the biochar represented 10-15% in weight. It was observed that the highest activation was achieved at a temperature of 800 °C, the specific surface increased with time but, on the contrary, high loss of matter was observed. At 600 °C, although there was an important increase of the specific surface and the volume of micropores, at this temperature it was observed that the activation time was not an influential parameter. Finally, at 400 °C it was observed that the activation process was not very significant. Assessing the average pore diameter it was found that the lowest value corresponded to the activation temperature of 600 °C, which indicated the development of microporosity. When the activation temperature increases up to 800 °C the pore diameter increased developing mesoporosity. PMID:27668291

  5. Activated carbon from flash pyrolysis of eucalyptus residue.

    PubMed

    Grima-Olmedo, C; Ramírez-Gómez, Á; Gómez-Limón, D; Clemente-Jul, C

    2016-09-01

    Forestry waste (eucalyptus sp) was converted into activated carbon by initial flash pyrolysis followed carbonization and CO2 activation. These residues were obtained from a pilot plant in Spain that produces biofuel, the biochar represented 10-15% in weight. It was observed that the highest activation was achieved at a temperature of 800 °C, the specific surface increased with time but, on the contrary, high loss of matter was observed. At 600 °C, although there was an important increase of the specific surface and the volume of micropores, at this temperature it was observed that the activation time was not an influential parameter. Finally, at 400 °C it was observed that the activation process was not very significant. Assessing the average pore diameter it was found that the lowest value corresponded to the activation temperature of 600 °C, which indicated the development of microporosity. When the activation temperature increases up to 800 °C the pore diameter increased developing mesoporosity.

  6. Wetting and Non-Wetting Models of Black Carbon Activation

    NASA Astrophysics Data System (ADS)

    Henson, B. F.; Laura, S.

    2006-12-01

    We present the results of recent modeling studies on the activation of black carbon (BC) aerosol to form cloud condensation nuclei (CCN). We use a model of BC activation based on a general modification of the Koehler equation for insoluble activation in which we introduce a term based on the activity of water adsorbed on the particle surface. We parameterize the model using the free energy of adsorption, a parameter directly comparable to laboratory measurements of water adsorption on carbon. Although the model of the water- surface interaction is general, the form of the activation equation that results depends upon a further model of the distribution of water on the particle. One possible model involves the symmetric growth of a water shell around the isoluble particle core (wetting). This model predicts upper and lower bounding curves for the activation supersaturation given by the range of water interaction energies from hydrophobic to hydrophilic which are in agreement with a large body of recent activation data. The resulting activation diameters are from 3 to 10 times smaller than activation of soluble particles of identical dry diameter. Another possible model involves an exluded liquid droplet growing in contact with the particle (non-wetting). The geometry of this model much more resembles classic assumptions of heterogeneous nucleation theory. This model can yield extremely high activation supersaturation as a function of diameter, as has been observed in some experiments, and enables calculations in agreement with some of these results. We discuss these two geometrical models of water growth, the different behaviors predicted by the resulting activation equation, and the means to determine which model of growth is appropriate for a given BC particle characterized by either water interaction energy or morphology. These simple models enable an efficient and physically reasonable means to calculate the activation of BC aerosol to form CCN based upon a

  7. Ultrahigh surface area carbon from carbonated beverages. Combining self-templaing process and in situ activation

    SciTech Connect

    Zhang, Pengfei; Zhang, Zhiyong; Chen, Jihua; Dai, Sheng

    2015-05-11

    Ultrahigh surface area carbons (USACs, e.g., >2000 m2/g) are attracting tremendous attention due to their outstanding performance in energy-related applications. The state-of-art approaches to USACs involve templating or activation methods and all these techniques show certain drawbacks. In this work, a series of USACs with specific surface areas up to 3633 m2/g were prepared in two steps: hydrothermal carbonization (200 °C) of carbonated beverages (CBs) and further thermal treatment in nitrogen (600–1000 °C). The rich inner porosity is formed by a self-templated process during which acids and polyelectrolyte sodium salts in the beverage formulas make some contribution. This strategy covers various CBs such as Coca Cola®, Pepsi Cola®, Dr. Pepper®, andFanta® and it enables an acceptable product yield (based on sugars), for example: 21 wt% for carbon (2940 m2/g) from Coca Cola®. Being potential electrode materials for supercapacitors, those carbon materials possessed a good specific capacitance (57.2–185.7 F g-1) even at a scan rate of 1000 mV s-1. Thus, a simple and efficient strategy to USACs has been presented.

  8. Ultrahigh surface area carbon from carbonated beverages. Combining self-templaing process and in situ activation

    DOE PAGES

    Zhang, Pengfei; Zhang, Zhiyong; Chen, Jihua; Dai, Sheng

    2015-05-11

    Ultrahigh surface area carbons (USACs, e.g., >2000 m2/g) are attracting tremendous attention due to their outstanding performance in energy-related applications. The state-of-art approaches to USACs involve templating or activation methods and all these techniques show certain drawbacks. In this work, a series of USACs with specific surface areas up to 3633 m2/g were prepared in two steps: hydrothermal carbonization (200 °C) of carbonated beverages (CBs) and further thermal treatment in nitrogen (600–1000 °C). The rich inner porosity is formed by a self-templated process during which acids and polyelectrolyte sodium salts in the beverage formulas make some contribution. This strategy coversmore » various CBs such as Coca Cola®, Pepsi Cola®, Dr. Pepper®, andFanta® and it enables an acceptable product yield (based on sugars), for example: 21 wt% for carbon (2940 m2/g) from Coca Cola®. Being potential electrode materials for supercapacitors, those carbon materials possessed a good specific capacitance (57.2–185.7 F g-1) even at a scan rate of 1000 mV s-1. Thus, a simple and efficient strategy to USACs has been presented.« less

  9. 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. PMID:23794416

  10. Carbon-enriched coal fly ash as a precursor of activated carbons for SO2 removal.

    PubMed

    Izquierdo, M T; Rubio, B

    2008-06-30

    Carbon-enriched coal fly ash was evaluated in this work as a low-cost adsorbent for SO2 removal from stack gases. The unburned carbon in coal fly ash was concentrated by mechanical sieving and vegetal oil agglomeration. The carbon concentrates were activated with steam at 900 degrees C in order to develop porosity onto the samples. The performance of these samples in the SO2 abatement was tested in the following conditions: 100 degrees C, 1000 ppmv SO2, 5% O2, 6% water vapor. A good SO2 removal capacity was shown by some of the studied samples that can be related to their textural properties. Cycles of SO2 adsorption/regeneration were carried out in order to evaluate the possibility of thermal regeneration and re-use of these carbons. Regeneration of the exhausted carbons was carried out at 400 degrees C of temperature and a flow of 25 ml/min of Ar. After each cycle, the SO2 removal capacity of the sample decreases.

  11. Activation and micropore structure determination of activated carbon-fiber composites

    SciTech Connect

    Jagtoyen, M.; Derbyshire, F.; Kimber, G.

    1997-09-05

    Rigid, high surface area activated carbon fiber composites have been produced with high permeabilities for environmental applications in gas and water purification. These novel monolithic adsorbents can be produced in single pieces to a given size and shape. The project involves a collaboration between the Oak Ridge National Laboratory (ORNL) and the Center for Applied Energy Research (CAER), University of Kentucky. The carbon fiber composites are produced at the ORNL and activated at the CAER using different methods, with the aims of producing a uniform degree of activation, and of closely controlling pore structure and adsorptive properties. The main focus of the present work has been to find a satisfactory means to uniformly activate large samples of carbon fiber composites and produce controlled pore structures. Several environmental applications have been explored for the activated carbon fiber composites. One of these was to evaluate the activated composites for the separation of CH{sub 4}-CO{sub 2} mixtures, and an apparatus was constructed specifically for this purpose. The composites were further evaluated in the cyclic recovery of volatile organics. The activated carbon fiber composites have also been tested for possible water treatment applications by studying the adsorption of sodium pentachlorophenolate, PCP.

  12. Removal of carbonyl sulfide using activated carbon adsorption.

    PubMed

    Sattler, Melanie L; Rosenberk, Ranjith Samuel

    2006-02-01

    Wastewater treatment plant odors are caused by compounds such as hydrogen sulfide (H2S), methyl mercaptans, and carbonyl sulfide (COS). One of the most efficient odor control processes is activated carbon adsorption; however, very few studies have been conducted on COS adsorption. COS is not only an odor causing compound but is also listed in the Clean Air Act as a hazardous air pollutant. Objectives of this study were to determine the following: (1) the adsorption capacity of 3 different carbons for COS removal; (2) the impact of relative humidity (RH) on COS adsorption; (3) the extent of competitive adsorption of COS in the presence of H2S; and (4) whether ammonia injection would increase COS adsorption capacity. Vapor phase react (VPR; reactivated), BPL (bituminous coal-based), and Centaur (physically modified to enhance H2S adsorption) carbons manufactured by Calgon Carbon Corp. were tested in three laboratory-scale columns, 6 in. in depth and 1 in. in diameter. Inlet COS concentrations varied from 35 to 49 ppmv (86-120 mg/m3). RHs of 17%, 30%, 50%, and 90% were tested. For competitive adsorption studies, H2S was tested at 60 ppmv, with COS at 30 ppmv. COS, RH, H2S, and ammonia concentrations were measured using an International Sensor Technology Model IQ-350 solid state sensor, Cole-Parmer humidity stick, Interscan Corp. 1000 series portable analyzer, and Drager Accuro ammonia sensor, respectively. It was found that the adsorption capacity of Centaur carbon for COS was higher than the other two carbons, regardless of RH. As humidity increased, the percentage of decrease in adsorption capacity of Centaur carbon, however, was greater than the other two carbons. The carbon adsorption capacity for COS decreased in proportion to the percentage of H2S in the gas stream. More adsorption sites appear to be available to H2S, a smaller molecule. Ammonia, which has been found to increase H2S adsorption capacity, did not increase the capacity for COS.

  13. RADIOACTIVE DEMONSTRATIONS OF FLUIDIZED BED STEAM REFORMING WITH ACUTAL HANFORD LOW ACTIVITY WASTES VERIFYING FBSR AS A SUPPLEMENTARY TREATMENT

    SciTech Connect

    Jantzen, C.; Crawford, C.; Burket, P.; Bannochie, C.; Daniel, G.; Nash, C.; Cozzi, A.; Herman, C.

    2012-01-12

    The U.S. Department of Energy's Office of River Protection is responsible for the retrieval, treatment, immobilization, and disposal of Hanford's tank waste. Currently there are approximately 56 million gallons of highly radioactive mixed wastes awaiting treatment. A key aspect of the River Protection Project cleanup mission is to construct and operate the Waste Treatment and Immobilization Plant (WTP). The WTP will separate the tank waste into high-level waste (HLW) and low-activity waste (LAW) fractions, both of which will subsequently be vitrified. The projected throughput capacity of the WTP LAW Vitrification Facility is insufficient to complete the cleanup mission in the time frame required by the Hanford Federal Facility Agreement and Consent Order, also known as the Tri-Party Agreement (TPA). Therefore, Supplemental Treatment is required both to meet the TPA treatment requirements as well as to more cost effectively complete the tank waste treatment mission. Fluidized Bed Steam Reforming (FBSR) is one of the supplementary treatments being considered. FBSR offers a moderate temperature (700-750 C) continuous method by which LAW and other secondary wastes can be processed irrespective of whether they contain organics, nitrates/nitrites, sulfates/sulfides, chlorides, fluorides, and/or radio-nuclides like I-129 and Tc-99. Radioactive testing of Savannah River LAW (Tank 50) shimmed to resemble Hanford LAW and actual Hanford LAW (SX-105 and AN-103) have produced a ceramic (mineral) waste form which is the same as the non-radioactive waste simulants tested at the engineering scale. The radioactive testing demonstrated that the FBSR process can retain the volatile radioactive components that cannot be contained at vitrification temperatures. The radioactive and nonradioactive mineral waste forms that were produced by co-processing waste with kaolin clay in an FBSR process are shown to be as durable as LAW glass.

  14. 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.

  15. Cost and performance of activated carbon injection for mercury control

    SciTech Connect

    2006-08-15

    Activated carbon injection (ACI) is one technology being developed to absorb mercury from mercury emitted from coal-fired power plants. In 2003/04, the USDOE and NETL selected 14 projects to test and evaluate mercury control technologies. While field testing is still ongoing, DOE/NETL recently completed an economic analysis of mercury control for six test sites spanning three ACI variations - conventional powdered activated carbon (PAC), brominated PAC and conventional PAC combined with a sorbent enhancement additive (SEA) applied to the coal. To evaluate the progress of the field testing program and discern the performance of ACI, a data adjustment methodology was developed to account for baseline methane capture. This data were used to perform economic analyses to achieve low, mid and high levels of mercury control. The costs are given in the article. Full details are available on the DOE/NETL website, www.netl.doe.gov. 2 figs., 1 photo.

  16. Predictions of adsorption equilibria of nonpolar hydrocarbons onto activated carbon

    SciTech Connect

    Do, D.D.; Wang, K.

    1998-12-08

    This paper presents a new approach to analyze the adsorption equilibria of nonpolar hydrocarbons onto activated carbon. The kinetic theory of gases and the 10-4-3 potential energy were employed to describe the adsorption process inside micropores. On the basis of this theory, a general isotherm model was proposed which possesses the potential capability of predicting the adsorption equilibria of an adsorbent by using the knowledge of its microporous structure and molecular properties of adsorbates. Experimental data of gases and vapors on Ajax activated carbon were employed to examine the model. Adsorption equilibria of binary mixtures were also investigated with the model, and it is shown that the model is capable of simulating the nonideal, or azeotropic, adsorption behaviors resulting from the structural heterogeneity of the adsorbent.

  17. Activated carbon treatment of municipal solid waste incineration flue gas.

    PubMed

    Lu, Shengyong; Ji, Ya; Buekens, Alfons; Ma, Zengyi; Jin, Yuqi; Li, Xiaodong; Yan, Jianhua

    2013-02-01

    Activated carbon injection is widely used to control dioxins and mercury emissions. Surprisingly little attention has been paid to its modelling. This paper proposes an expansion of the classical Everaerts-Baeyens model, introducing the expression of fraction of free adsorption sites, f (s), and asserting the significant contribution of fly ash to dioxins removal. Moreover, the model monitors dioxins partitioning between vapour and particulate phase, as well as removal efficiency for each congener separately. The effects of the principal parameters affecting adsorption are analysed according to a semi-analytical, semi-empirical model. These parameters include temperature, contact time during entrained-flow, characteristics (grain-size, pore structure, specific surface area) and dosage of activated carbon, lignite cokes or mineral adsorbent, fly ash characteristics and concentration, and type of incinerator plant. PMID:23179511

  18. Liquid Phase Adsorption of α-Tocopherol by Activated Carbon

    NASA Astrophysics Data System (ADS)

    Bono, Awang; Ming, Chu Chi; Sundang, Murni

    α-Tocopherol or commonly called vitamin E can be found in major commercial vegetable oils such as soya oil and palm oil. However the existence in these oil is in low concentration. The recovery of low concentration of α-tocopherol from palm oils is increasingly popular. Adsorption technique for the recovery of α-tocopherol from palm oil is believed to be much lower in cost and more effective. As a case study in this work, activated carbon is chosen as the adsorbent and ethanol as the solvent. The adsorption equilibria of α-tocopherol onto activated carbon was conducted in batch and the concentration of α-tocopherol was identified by LCMS. Langmuirian monolayer adsorption theory was used for the analysis of the isotherm equilibria. The adsorptivity of α-tocopherol onto activated carbon was identified. The adsorption equilibria at low concentration found to be linear. The breakthrough curve was then generated using model assuming isothermal, single transition trace component with intraparticle diffusion. Sensitivity test on the curve indicated that the system is very sensitive to changes in diffusitivity and passive to changes on the equilibrium constant.

  19. Adsorption of dyes onto activated carbon prepared from olive stones.

    PubMed

    Najar-Souissi, Souad; Ouederni, Abdelmottaleb; Ratel, Abdelhamid

    2005-01-01

    Activated carbon was produced from olive stones(OSAC) by a physical process in two steps. The adsorption character of this activated carbon was tested on three colour dyes molecules in aqueous solution: Methylene blue (MB), Rhodamine B (RB) and Congo Red(CR). The adsorption equilibrium was studied through isotherms construction at 30 degrees C, which were well described by Langmuir model. The adsorption capacity on the OSAC was estimated to be 303 mg/g, 217 mg/g and 167 mg/g respectively for MB, RB and CR. This activated carbon has a similar adsorption properties to that of commercial ones and show the same adsorption performances. The adsorption kinetics of the MB molecule in aqueous solution at different initial concentrations by OSAC was also studied. Kinetic experiments were well fitted by a simple intra-particle diffusion model. The measured kinetics constant was influenced by the initial concentration and we found the following correlation: Kid = 1.55 C0(0.51). PMID:16465895

  20. [Adsorption of perfluorooctanesulfonate (PFOS) onto modified activated carbons].

    PubMed

    Tong, Xi-Zhen; Shi, Bao-You; Xie, Yue; Wang, Dong-Sheng

    2012-09-01

    Modified coal and coconut shell based powdered activated carbons (PACs) were prepared by FeCl3 and medium power microwave treatment, respectively. Batch experiments were carried out to evaluate the characteristics of adsorption equilibrium and kinetics of perfluorooctanesulfonate (PFOS) onto original and modified PACs. Based on pore structure and surface functional groups characterization, the adsorption behaviors of modified and original PACs were compared. The competitive adsorption of humic acid (HA) and PFOS on original and modified coconut shell PACs were also investigated. Results showed that both Fe3+ and medium power microwave treatments changed the pore structure and surface functional groups of coal and coconut shell PACs, but the changing effects were different. The adsorption of PFOS on two modified coconut shell-based PACs was significantly improved. While the adsorption of modified coal-based activated carbons declined. The adsorption kinetics of PFOS onto original and modified coconut shell-based activated carbons were the same, and the time of reaching adsorption equilibrium was about 6 hours. In the presence of HA, the adsorption of PFOS by modified PAC was reduced but still higher than that of the original. PMID:23243870

  1. Restricted dynamics of molecular hydrogen confined in activated carbon nanopores

    SciTech Connect

    Contescu, Cristian I; Saha, Dipendu; Gallego, Nidia C; Mamontov, Eugene; Kolesnikov, Alexander I; Bhat, Vinay V

    2012-01-01

    Quasi-elastic neutron scattering was used for characterization of dynamics of molecular hydrogen confined in narrow nanopores of two activated carbon materials: PFAC (derived from polyfurfuryl alcohol) and UMC (ultramicroporous carbon). Fast, but incomplete ortho-para conversion was observed at 10 K, suggesting that scattering originates from the fraction of unconverted ortho isomer which is rotation-hindered because of confinement in nanopores. Hydrogen molecules entrapped in narrow nanopores (<7 ) were immobile below 22-25 K. Mobility increased rapidly with temperature above this threshold, which is 8 K higher than the melting point of bulk hydrogen. Diffusion obeyed fixed-jump length mechanism, indistinguishable between 2D and 3D processes. Thermal activation of diffusion was characterized between ~22 and 37 K, and structure-dependent differences were found between the two carbons. Activation energy of diffusion was higher than that of bulk solid hydrogen. Classical notions of liquid and solid do not longer apply for H2 confined in narrow nanopores.

  2. Enzymatic synthesis of farnesyl laurate in organic solvent: initial water activity, kinetics mechanism, optimization of continuous operation using packed bed reactor and mass transfer studies.

    PubMed

    Rahman, N K; Kamaruddin, A H; Uzir, M H

    2011-08-01

    The influence of water activity and water content was investigated with farnesyl laurate synthesis catalyzed by Lipozyme RM IM. Lipozyme RM IM activity depended strongly on initial water activity value. The best results were achieved for a reaction medium with an initial water activity of 0.11 since it gives the best conversion value of 96.80%. The rate constants obtained in the kinetics study using Ping-Pong-Bi-Bi and Ordered-Bi-Bi mechanisms with dead-end complex inhibition of lauric acid were compared. The corresponding parameters were found to obey the Ordered-Bi-Bi mechanism with dead-end complex inhibition of lauric acid. Kinetic parameters were calculated based on this model as follows: V (max) = 5.80 mmol l(-1) min(-1) g enzyme(-1), K (m,A) = 0.70 mmol l(-1) g enzyme(-1), K (m,B) = 115.48 mmol l(-1) g enzyme(-1), K (i) = 11.25 mmol l(-1) g enzyme(-1). The optimum conditions for the esterification of farnesol with lauric acid in a continuous packed bed reactor were found as the following: 18.18 cm packed bed height and 0.9 ml/min substrate flow rate. The optimum molar conversion of lauric acid to farnesyl laurate was 98.07 ± 0.82%. The effect of mass transfer in the packed bed reactor has also been studied using two models for cases of reaction limited and mass transfer limited. A very good agreement between the mass transfer limited model and the experimental data obtained indicating that the esterification in a packed bed reactor was mass transfer limited.

  3. Arsenate sorption by hydrous ferric oxide incorporated onto granular activated carbon with phenol formaldehyde resins coating.

    PubMed

    Zhuang, J M; Hobenshield, E; Walsh, T

    2008-04-01

    A simple and effective method was developed using phenol formaldehyde (PF) resins to immobilize hydrous ferric oxide (HFO) onto granular activated carbon (GAC). The resulting sorbent possesses advantages for both the ferric oxide and the GAC, such as a great As-affinity of ferric oxide, large surface area of GAC, and enhanced physical strength. The studies showed that within one hour this sorbent was able to remove 85% of As(V) from water containing an initial As(V) concentration of 1.74 mg l(-1). The As(V) adsorption onto the sorbent was found to follow a pseudo-second order kinetics model. The adsorption isotherms were interpreted in terms of the Langmuir and Freundlich models. The equilibrium data fitted very well to both models. Column tests showed that this sorbent was able to achieve residual concentrations of As(V) in a range of 0.1-2.0 microg l(-1) while continuously treating about 180 bed volume (BV, 130 ml-BV) of arsenate water with an initial As(V) concentration of 1886 microg l(-1) at a filtration rate of 13.5 ml min(-1), i.e., an empty bed contact time (EBCT) of 9.6 min and a gram sorbent contact time (GSCT) of 0.15 min. After passing 635 BV of arsenate water, the exhausted sorbent was then tested by the Toxicity Characteristic Leaching Procedure (TCLP, US EPA Method 1311) test, and classified as non-hazardous for disposal. Hence, this HFO-PF-coated GAC has the capability to remove As(V) from industrial wastewater containing As(V) levels of about 2 mg l(-1). PMID:18619145

  4. Granular biochar compared with activated carbon for wastewater treatment and resource recovery.

    PubMed

    Huggins, Tyler M; Haeger, Alexander; Biffinger, Justin C; Ren, Zhiyong Jason

    2016-05-01

    Granular wood-derived biochar (BC) was compared to granular activated carbon (GAC) for the treatment and nutrient recovery of real wastewater in both batch and column studies. Batch adsorption studies showed that BC material had a greater adsorption capacity at the high initial concentrations of total chemical oxygen demand (COD-T) (1200 mg L(-1)), PO4 (18 mg L(-1)), and NH4 (50 mg L(-1)) compared to GAC. Conversely the BC material showed a lower adsorption capacity for all concentrations of dissolved chemical oxygen demand (COD-D) and the lower concentrations of PO4 (5 mg L(-1)) and NH4 (10 mg L(-1)). Packed bed column studies showed similar average COD-T removal rate for BC with 0.27 ± 0.01 kg m(-3) d(-1) and GAC with 0.24 ± 0.01 kg m(-3) d(-1), but BC had nearly twice the average removal rate (0.41 ± 0.08 kg m(-3) d(-3)) compared to GAC during high COD-T concentrations (>500 mg L(-1)). Elemental analysis showed that both materials accumulated phosphorous during wastewater treatment (2.6 ± 0.4 g kg(-1) and 1.9 ± 0.1 g kg(-1) for BC and GAC respectively). They also contained high concentrations of other macronutrients (K, Ca, and Mg) and low concentrations of metals (As, Cd, Cr, Pb, Zn, and Cu). The good performance of BC is attributed to its macroporous structure compared with the microporous GAC. These favorable treatment data for high strength wastewater, coupled with additional life-cycle benefits, helps support the use of BC in packed bed column filters for enhanced wastewater treatment and nutrient recovery. PMID:26954576

  5. The effects of activation temperature on physico-chemical characteristics of activated carbons derived from biomass wastes

    NASA Astrophysics Data System (ADS)

    Sutrisno, Bachrun; Hidayat, Arif

    2015-12-01

    This research focused on investigating in the effect of activation temperature on the physico-chemical properties of palm empty fruit bunch (PEFB) based activated carbon prepared by physical activation with carbon dioxide. The activation temperature was studied in the range of 400-800°C by keeping the activation temperature at 800°C for 120 min. It was found that the porous properties of activated carbon decreased with an increase in carbonization temperature. The activated carbons prepared at the highest activation temperature at 800°C and activation time of 120 min gave the activated carbon with the highest of BET surface area and pore volume of 938 m2/g and 0.4502 cm3/g, respectively

  6. Liquid-Phase Adsorption of Phenol onto Activated Carbons Prepared with Different Activation Levels.

    PubMed

    Hsieh; Teng

    2000-10-01

    The influence of the pore size distribution of activated carbon on the adsorption of phenol from aqueous solutions was explored. Activated carbons with different porous structures were prepared by gasifying a bituminous coal char to different extents of burn-off. The results of adsorption experiments show that the phenol capacity of these carbons does not proportionally increase with their BET surface area. This reflects the heterogeneity of the carbon surface for adsorption. The pore size distributions of these carbons, determined according to the Dubinin-Stoeckli equation, were found to vary with the burn-off level. By incorporating the distribution with the Dubinin-Radushkevich equation using an inverse proportionality between the micropore size and the adsorption energy, the isotherms for the adsorption of phenol onto these carbons can be well predicted. The present study has demonstrated that the heterogeneity of carbon surface for the phenol adsorption can be attributed to the different energies required for adsorption in different-size micropores. Copyright 2000 Academic Press. PMID:10998301

  7. Characterising biofilm development on granular activated carbon used for drinking water production.

    PubMed

    Gibert, Oriol; Lefèvre, Benoît; Fernández, Marc; Bernat, Xavier; Paraira, Miquel; Calderer, Montse; Martínez-Lladó, Xavier

    2013-03-01

    Under normal operation conditions, granular activated carbon (GAC) employed in drinking water treatment plants (DWTPs) for natural organic matter (NOM) removal can be colonised by microorganisms which can eventually establish active biofilms. The formation of such biofilms can contribute to NOM removal by biodegradation, but also in clogging phenomena that can make necessary more frequent backwashes. Biofilm occurrence and evolution under full-scale-like conditions (i.e. including periodic backwashing) are still uncertain, and GAC filtration is usually operated with a strong empirical component. The aim of the present study was to assess the formation and growth, if any, of biofilm in a periodically backwashed GAC filter. For this purpose, an on-site pilot plant was assembled and operated to closely mimic the GAC filters installed in the DWTP in Sant Joan Despí (Barcelona, Spain). The study comprised a monitoring of both water and GAC cores withdrawn at various depths and times throughout 1 year operation. The biomass parameters assessed were total cell count by confocal laser scanning microscopy (CLSM), DNA and adenosine triphosphate (ATP). Visual examination of GAC particles was also conducted by high-resolution field emission scanning electron microscopy (FESEM). Additionally, water quality and GAC surface properties were monitored. Results provided insight into the extent and spatial distribution of biofilm within the GAC bed. To sum up, it was found that backwashing could physically detach bacteria from the biofilm, which could however build back up to its pre-backwashing concentration before next backwashing cycle.

  8. Investigation on the mechanism of H(2)S removal by biological activated carbon in a horizontal biotrickling filter.

    PubMed

    Duan, Huiqi; Yan, Rong; Koe, Lawrence Choon Chiaw

    2005-12-01

    The use of supporting media for the immobilization of microorganisms is widely known to provide a surface for microbial growth and a shelter that protects the microorganisms from inhibitory compounds. In our previous studies, activated carbon (AC) alone used as a support medium for H(2)S biological removal was proved prompt and efficient in a bench-scale biofilter and biotrickling filter. In this study, the mechanisms of H(2)S elimination using microbial immobilized activated carbon, i.e., biological activated carbon (BAC), are investigated. A series of BAC as supporting medium were taken from the inlet to outlet of a bench-scale horizontal biotrickling filter to examine the different effects of physical/chemical adsorption and microbial degradation on the overall removal of H(2)S. The surface properties of BAC together with virgin and exhausted carbon (after H(2)S breakthrough test, non-microbial immobilization) were characterized using the sorption of nitrogen (Braunner-Emmett-Teller test), scanning electron microscopy (SEM), surface pH, thermal, carbon-hydrogen-nitrogen-sulfur (CHNS) elemental and Fourier transform infrared (FTIR) analyses. Tests of porosity and surface area provide detailed information about the pore structure of BAC along the bed facilitating the understanding of potential pore blockages due to biofilm coating. A correlation between the available surface area and pore volume with the extent of microbial immobilization and H(2)S uptake is evidenced. SEM photographs show the direct carbon structure and biofilm coated on carbon surface. FTIR spectra, differential thermogravimetric curves and CHNS results indicate less diversity of H(2)S oxidation products on BAC than those previously observed on exhausted carbon from H(2)S adsorption only. The predominant oxidation product on BAC is sulfuric acid, and biofilm is believed to enhance the oxidation of H(2)S on carbon surface. The combination of biodegradation and physical adsorption of using BAC in

  9. Removal efficiencies for 136 tetra- through octa-chlorinated dibenzo-p-dioxins and dibenzofuran congeners with activated carbons.

    PubMed

    Zhou, Xu-Jian; Li, Xiao-Dong; Ni, Ming-Jiang; Cen, Ke-Fa

    2015-11-01

    In this study, the removal efficiency of 136 tetra- to octa-chlorinated dibenzo-p-dioxin (CDD)/furan (F) congeners from a nitrogen + oxygen carrier gas was studied using a laboratory-scale, fixed bed adsorption system. Two kinds of activated carbon with dissimilar pore structures were used as adsorbents. The total concentration of polychlorinated dibenzo-p-dioxins/furans (PCDD/Fs) in the source gas was 541 ng/Nm(3) and that of the 17 toxic 2,3,7,8-substituted PCDD/Fs 96.35 ng/Nm(3), accounting for 17.8% of the total original weight amount. Their toxic equivalent quantity (TEQ) was 8.31 ng I-TEQ/Nm(3). For both activated carbons, the removal efficiencies of the ten PCDD/F homologue groups rise with chlorine substitution number. The removal efficiencies vary approximately as a power function of vapor pressure (correlation coefficients r(2) = 0.93 and 0.81, respectively). Competitive adsorption and desorption occur as adsorption time went on, causing elution of the lower chlorinated homologues, i.e. tetra-CDD/F and Penta-CDD/F congeners. In addition, there are significantly different concentration distributions for isomers in the same homologue groups. However, their removal efficiencies have weak correlation with their initial concentrations. The correlation coefficients are from -0.47 to 0.32 and from -0.57 to 0.46 respectively for the two kinds of activated carbons.

  10. Degradation of paracetamol by catalytic wet air oxidation and sequential adsorption - Catalytic wet air oxidation on activated carbons.

    PubMed

    Quesada-Peñate, I; Julcour-Lebigue, C; Jáuregui-Haza, U J; Wilhelm, A M; Delmas, H

    2012-06-30

    The concern about the fate of pharmaceutical products has raised owing to the increasing contamination of rivers, lakes and groundwater. The aim of this paper is to evaluate two different processes for paracetamol removal. The catalytic wet air oxidation (CWAO) of paracetamol on activated carbon was investigated both as a water treatment technique using an autoclave reactor and as a regenerative treatment of the carbon after adsorption in a sequential fixed bed process. Three activated carbons (ACs) from different source materials were used as catalysts: two microporous basic ACs (S23 and C1) and a meso- and micro-porous acidic one (L27). During the first CWAO experiment the adsorption capacity and catalytic performance of fresh S23 and C1 were higher than those of fresh L27 despite its higher surface area. This situation changed after AC reuse, as finally L27 gave the best results after five CWAO cycles. Respirometry tests with activated sludge revealed that in the studied conditions the use of CWAO enhanced the aerobic biodegradability of the effluent. In the ADOX process L27 also showed better oxidation performances and regeneration efficiency. This different ageing was examined through AC physico-chemical properties.

  11. Preparation of functionalized and metal-impregnated activated carbon by a single-step activation method

    NASA Astrophysics Data System (ADS)

    Dastgheib, Seyed A.; Ren, Jianli; Rostam-Abadi, Massoud; Chang, Ramsay

    2014-01-01

    A rapid method to prepare functionalized and metal-impregnated activated carbon from coal is described in this paper. A mixture of ferric chloride and a sub-bituminous coal was used to demonstrate simultaneous coal activation, chlorine functionalization, and iron/iron oxides impregnation in the resulting porous carbon products. The FeCl3 concentration in the mixture, the method to prepare the FeCl3-coal mixture (solid mixing or liquid impregnation), and activation atmosphere and temperature impacted the surface area and porosity development, Cl functionalization, and iron species impregnation and dispersion in the carbon products. Samples activated in nitrogen or a simulated flue gas at 600 or 1000 °C for 1-2 min had surface areas up to ∼800 m2/g, bulk iron contents up to 18 wt%, and surface chlorine contents up to 27 wt%. Potential catalytic and adsorption application of the carbon materials was explored in catalytic wet air oxidation (CWAO) of phenol and adsorption of ionic mercury from aqueous solutions. Results indicated that impregnated activated carbons outperformed their non-impregnated counterparts in both the CWAO and adsorption tests.

  12. Large-aperture active optical carbon fiber reinforced polymer mirror

    NASA Astrophysics Data System (ADS)

    Jungwirth, Matthew E. L.; Wilcox, Christopher C.; Wick, David V.; Baker, Michael S.; Hobart, Clinton G.; Milinazzo, Jared J.; Robichaud, Joseph; Romeo, Robert C.; Martin, Robert N.; Ballesta, Jerome; Lavergne, Emeric; Dereniak, Eustace L.

    2013-05-01

    An active reflective component can change its focal length by physically deforming its reflecting surface. Such elements exist at small apertures, but have yet to be fully realized at larger apertures. This paper presents the design and initial results of a large-aperture active mirror constructed of a composite material called carbon fiber reinforced polymer (CFRP). The active CFRP mirror uses a novel actuation method to change radius of curvature, where actuators press against two annular rings placed on the mirror's back. This method enables the radius of curvature to increase from 2000mm to 2010mm. Closed-loop control maintains good optical performance of 1.05 waves peak-to-valley (with respect to a HeNe laser) when the active CFRP mirror is used in conjunction with a commercial deformable mirror.

  13. 40 CFR 60.1330 - How do I monitor the injection rate of activated carbon?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... activated carbon? 60.1330 Section 60.1330 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Requirements § 60.1330 How do I monitor the injection rate of activated carbon? If your municipal waste combustion unit uses activated carbon to control dioxins/furans or mercury emissions, you must meet...

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

    DOEpatents

    Srinivasachar, Srivats; Benson, Steven; Crocker, Charlene; Mackenzie, Jill

    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.

  15. Preparation and characterization of activated carbon from marine macro-algal biomass.

    PubMed

    Aravindhan, R; Raghava Rao, J; Unni Nair, B

    2009-03-15

    Activated carbons prepared from two macro-algal biomass Sargassum longifolium (SL) and Hypnea valentiae (HV) have been examined for the removal of phenol from aqueous solution. The activated carbon has been prepared by zinc chloride activation. Experiments have been carried out at different activating agent/precursor ratio and carbonization temperature, which had significant effect on the pore structure of carbon. Developed activated carbon has been characterized by BET surface area (S(BET)) analysis and iodine number. The carbons, ZSLC-800 and ZHVC-800, showed surface area around 802 and 783 m(2)g(-1), respectively. The activated carbon developed showed substantial capability to adsorb phenol from aqueous solutions. The kinetic data were fitted to the models of pseudo-first-order, pseudo-second-order and intraparticle diffusion models. Column studies have also been carried out with ZSLC-800 activated carbon.

  16. Barrier properties of poly(vinyl alcohol) membranes containing carbon nanotubes or activated carbon.

    PubMed

    Surdo, Erin M; Khan, Iftheker A; Choudhury, Atif A; Saleh, Navid B; Arnold, William A

    2011-04-15

    Carbon nanotube addition has been shown to improve the mechanical properties of some polymers. Because of their unique adsorptive properties, carbon nanotubes may also improve the barrier performance of polymers used in contaminant containment. This study compares the barrier performance of poly(vinyl alcohol) (PVA) membranes containing single-walled carbon nanotubes (SWCNTs) to that for PVA containing powdered activated carbon (PAC). Raw and surface-functionalized versions of each sorbent were tested for their abilities to adsorb 1,2,4-trichlorobenzene and Cu(2+), representing the important hydrophobic organic and heavy metal contaminant classes, as they diffused across the PVA. In both cases, PAC (for 1,2,4-trichlorobenzene) and functionalized PAC (for Cu(2+)) outperformed SWCNTs on a per mass basis by trapping more of the contaminants within the barrier membrane. Kinetics of sorption are important in evaluating barrier properties, and poor performance of SWCNT-containing membranes as 1,2,4-TCB barriers is attributed to kinetic limitations. PMID:21349636

  17. Development of carbon free diffusion layer for activated carbon air cathode of microbial fuel cells.

    PubMed

    Yang, Wulin; Kim, Kyoung-Yeol; Logan, Bruce E

    2015-12-01

    The fabrication of activated carbon air cathodes for larger-scale microbial fuel cells requires a diffusion layer (DL) that is highly resistant to water leakage, oxygen permeable, and made using inexpensive materials. A hydrophobic polyvinylidene fluoride (PVDF) membrane synthesized using a simple phase inversion process was examined as a low cost ($0.9/m(2)), carbon-free DL that prevented water leakage at high pressure heads compared to a polytetrafluoroethylene/carbon black DL ($11/m(2)). The power density produced with a PVDF (20%, w/v) DL membrane of 1400±7mW/m(2) was similar to that obtained using a wipe DL [cloth coated with poly(dimethylsiloxane)]. Water head tolerance reached 1.9m (∼19kPa) with no mesh supporter, and 2.1m (∼21kPa, maximum testing pressure) with a mesh supporter, compared to 0.2±0.05m for the wipe DL. The elimination of carbon black from the DL greatly simplified the fabrication procedure and further reduced overall cathode costs. PMID:26342345

  18. An active carbon catalyst prevents coke formation from asphaltenes during the hydrocracking of vacuum residue

    SciTech Connect

    Fukuyama, H.; Terai, S.

    2007-07-01

    Active carbons were prepared by the steam activation of a brown coal char. The active carbon with mesopores showed greater adsorption selectivity for asphaltenes. The active carbon was effective at suppressing coke formation, even with the high hydrocracking conversion of vacuum residue. The analysis of the change in the composition of saturates, aromatics, resins, and asphaltenes in the cracked residue with conversion demonstrated the ability of active carbon to restrict the transformation of asphaltenes to coke. The active carbon that was richer in mesopores was presumably more effective at providing adsorption sites for the hydrocarbon free-radicals generated initially during thermal cracking to prevent them from coupling and polycondensing.

  19. An Update on Natural Products with Carbonic Anhydrase Inhibitory Activity.

    PubMed

    Karioti, Anastasia; Carta, Fabrizio; Supuran, Claudiu T

    2016-01-01

    Carbonic anhydrases (CAs, EC 4.2.1.1) catalyze the fundamental reaction of CO2 hydration in all living organisms, being actively involved in the regulation of a plethora of patho/physiological processes. They represent a typical example of enzyme convergent evolution, as six genetically unrelated families of such enzymes were described so far. It is more than 70 years that synthetic compounds, mainly sulfonamides, have been used in clinical practice as diuretics and systemic acting antiglaucoma drugs. Recent studies using natural product libraries and isolated constituents from natural sources (such as fungi and plants) have disclosed novel chemotypes possessing carbonic anhydrase inhibition activities. These natural sources offer new opportunities in the search for new and more effective carbonic anhydrase inhibitors, and may serve as new leads for the design and development of future drugs. This review will discuss the most recent advances in the search of naturally occurring products and their synthetic derivatives that inhibit the CAs and their mechanisms of action at molecular level. Plant extracts are not considered in the present review. PMID:26654592

  20. Passive, integrated measurement of indoor radon using activated carbon.

    PubMed

    George, A C

    1984-04-01

    Activated carbon canisters were tested to determine their adsorption and retention characteristics for radon. Our tests conducted indoors under typical conditions of temperature and relative humidity indicate that simple, inexpensive and maintenance-free passive devices containing 150-200 g of activated carbon can measure radon conveniently and adequately. The amount of radon absorbed in the collector is determined by counting the gamma rays from the decay products of radon. The lower limit of detection for radon is 0.2 pCi/l. for an exposure of 72 hr. Greater sensitivity can be obtained with larger counting systems and devices containing carbon with more surface area. Tests in a residential building and in a test chamber indicate that the measured radon in the canister is proportional to the mean concentration of radon during the period of exposure when correction for relative humidity is made. For practical situations encountered indoors, the device yields results accurate to within +/- 20%. Results from field measurements indicate that the use of the device is feasible.

  1. Novel electro-fenton approach for regeneration of activated carbon.

    PubMed

    Bañuelos, Jennifer A; Rodríguez, Francisco J; Manríquez Rocha, Juan; Bustos, Erika; Rodríguez, Adrián; Cruz, Julio C; Arriaga, L G; Godínez, Luis A

    2013-07-16

    An electro-Fenton-based method was used to promote the regeneration of granular activated carbon (GAC) previously adsorbed with toluene. Electrochemical regeneration experiments were carried out using a standard laboratory electrochemical cell with carbon paste electrodes and a batch electrochemical reactor. For each system, a comparison was made using FeSO4 as a precursor salt in solution (homogeneous system) and an Fe-loaded ion-exchange resin (Purolite C-100, heterogeneous system), both in combination with electrogenerated H2O2 at the GAC cathode. In the two cases, high regeneration efficiencies were obtained in the presence of iron using appropriate conditions of applied potential and adsorption-polarization time. Consecutive loading and regeneration cycles of GAC were performed in the reactor without great loss of the adsorption properties, only reducing the regeneration efficiency by 1% per cycle during 10 cycles of treatment. Considering that, in the proposed resin-containing process, the use of Fe salts is avoided and that GAC cathodic polarization results in efficient cleaning and regeneration of the adsorbent material, this novel electro-Fenton approach could constitute an excellent alternative for regenerating activated carbon when compared to conventional methods. PMID:23782426

  2. Laser light triggered-activated carbon nanosystem for cancer therapy.

    PubMed

    Chu, Maoquan; Peng, Jinliang; Zhao, Jiajia; Liang, Shanlu; Shao, Yuxiang; Wu, Qiang

    2013-02-01

    Among carbon-based nanomaterials, activated carbon (AC) may be an ideal candidate as a carrier for tumor therapeutic agents. Here we found a new property of nanoscale activated carbon (NAC) with narrow size distribution, namely the rapid conversion of light to thermal energy both in vitro and in vivo. An aqueous suspension of 200 μL of NAC (1 mg/mL) exhibited a rapid temperature increase of more than 35 °C after irradiation for 20 min with a 655-nm laser; this was within the temperature range for effective tumor treatment. We demonstrated that lung cancer cells (H-1299) incubated with bamboo nano-AC (BNAC) were killed with high efficiency after laser irradiation. In addition, mouse tumors with sizes smaller than the laser spot that had been injected with BNAC disappeared after irradiation. For tumors larger than the laser spot area, the incorporation of the photosensitizer ZnPc obviously increased the tumor growth inhibition efficiency of BNAC. BNAC-ZnPc was found to exhibit a synergistic effect when photothermal and photodynamic therapies were administered in combination. These results indicated that NAC can be used for high efficiency cancer phototherapy.

  3. Utilizing the fluidized bed to initiate water treatment on site

    SciTech Connect

    Ahmadvand, H.; Germann, G.; Gandee, J.P.; Buehler, V.T.

    1995-12-31

    Escalating wastewater disposal costs coupled with enforcement of stricter regulations push industrial sites previously without water treatment to treat on site. These sites, inexperienced in water treatment, require a treatment technology that is easily installed, operated, and maintained. The aerobic granular activated carbon (GAC) fluidized bed incorporates biological and adsorptive technologies into a simple, cost-effective process capable of meeting strict effluent requirements. Two case studies at industrial sites illustrate the installation and operation of the fluidized bed and emphasize the ability to use the fluidized bed singularly or as an integral component of a treatment system capable of achieving treatment levels that allow surface discharge and reinjection. Attention is focused on BTEX (benzene, toluene, ethylbenzene, and xylenes).

  4. Activation and Micropore Structure Determination of Activated Carbon-Fiber Composites

    SciTech Connect

    Jagtoyen, M.; Derbyshire, F.

    1999-04-23

    Previous work focused on the production of carbon fiber composites and subsequently activating them to induce adsorbent properties. One problem related to this approach is the difficulty of uniformly activating large composites. In order to overcome this problem, composites have been made from pre-activated fibers. The loss of surface area upon forming the composites after activation of the fibers was investigated. The electrical resistivity and strength of these composites were compared to those made by activation after forming. It was found that the surface area is reduced by about 35% by forming the composite from pre-activated fibers. However, the properties of the activated sample are very uniform: the variation in surface area is less than {+-}0.5%. So, although the surface area is somewhat reduced, it is believed that making composites from pre-activated fibers could be useful in applications where the BET surface area is not required to be very high. The strength of the composites produced from pre-activated fibers is lower than for composites activated after forming when the carbon burnoff is below 45%. For higher burnoffs, the strength of composites made with pre-activated fibers is as good or better. In both cases, there is a dramatic decrease in strength when the fiber:binder ratio is reduced below 4:1. The electrical resistivity is slightly higher for composites made from pre-activated fibers than for composites that are activated after forming, other parameters being constant (P-200 fibers, similar carbon burnoffs). For both types of composite the resistivity was also found to increase with carbon burnoff. This is attributed to breakage of the fiber causing shorter conductive paths. The electrical resistivity also increases when the binder content is lowered, which suggests that there are fewer solid contact points between the fibers.

  5. Adsorption and structural properties of soft-templated mesoporous carbons obtained by carbonization at different temperatures and KOH activation

    NASA Astrophysics Data System (ADS)

    Górka, Joanna; Zawislak, Aleksandra; Choma, Jerzy; Jaroniec, Mietek

    2010-06-01

    Two series of phenolic resin-based mesoporous carbons were prepared by soft-templating strategy, which involves the formation of thermosetting carbon precursor by polymerization of phloroglucinol and formaldehyde in hydrophilic mesodomains of a thermally decomposable triblock copolymer used as a soft-template. It was shown that the volumes of mesopores and micropores in the resulting carbons can be tuned by varying carbonization temperature of phenolic resins in the range from 400 to 1000 °C followed by the post-synthesis KOH activation at 700 °C. The highly microporous carbons were obtained by KOH activation of phenolic resins pyrolyzed at lower temperature (˜500 °C), while high temperature KOH activation (˜800 °C) afforded microporous carbons with preserved mesoporosity.

  6. Synthesis and characterization of vanadium nanoparticles on activated carbon and their catalytic activity in thiophene hydrodesulphurization

    NASA Astrophysics Data System (ADS)

    Pinto, Susana; D'Ornelas, Lindora; Betancourt, Paulino

    2008-06-01

    Vanadium nanoparticles (˜7 nm) stabilized on activated carbon were synthesized by the reduction of VCl 3·3THF with K[BEt 3H]. This material was characterized by inductive coupled plasma-atomic emission spectroscopy (ICP-AES), high-resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS) analyses. The catalytic performance of the carbon-supported vanadium was studied using thiophene hydrodesulfurization (HDS) as model reaction at 300 °C and P = 1 atm. The catalytic activity of the vanadium carbide phase on the activated carbon carrier was more significant than that of the reference catalysts, alumina supported NiMoS. The method proposed for the synthesis of such a catalyst led to an excellent performance of the HDS process.

  7. Preparation of activated carbons from cherry stones by activation with potassium hydroxide

    NASA Astrophysics Data System (ADS)

    Olivares-Marín, M.; Fernández-González, C.; Macías-García, A.; Gómez-Serrano, V.

    2006-06-01

    Using cherry stones, the preparation of activated carbon has been undertaken in the present study by chemical activation with potassium hydroxide. A series of KOH-activated products was prepared by varying the carbonisation temperature in the 400 900 °C range. Such products were characterised texturally by gas adsorption (N2, -196 °C), mercury porosimetry, and helium and mercury density measurements. FT-IR spectroscopy was also applied. The carbons prepared as a rule are microporous and macroporous solids. The degree of development of surface area and porosity increases with increasing carbonisation temperature. For the carbon heated at 900 °C the specific surface area (BET) is 1624 m2 g-1, the micropore volume is 0.67 cm3 g-1, the mesopore volume is 0.28 cm3 g-1, and the macropore volume is 1.84 cm3 g-1.

  8. 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.

  9. Activated carbon derived from carbon residue from