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Sample records for active surface carbon

  1. Technique for surface oxidation of activated carbon

    SciTech Connect

    Sircar, S.; Golden, T.C.

    1987-10-27

    A method of activating a carbon adsorbent is described, which comprises oxidizing the surface of the carbon adsorbent with a mild oxidizing acid in the presence of a metal oxidation catalyst at an elevated temperature and boiling the mixture of the carbon adsorbent, mild oxidizing acid and metal oxidation catalyst to dryness. Then rinse the surface oxidizing carbon adsorbent with water; and dry the rinsed surface oxidized carbon adsorbent. In a process for the removal of water or carbon dioxide from a gas stream containing water or carbon dioxide of the type wherein the gas stream containing water or carbon dioxide is contacted with a solid phase adsorbent under pressure-swing adsorption or thermal-swing adsorption processing conditions, the improvement is described comprising utilizing an adsorbent produced by the activation of a carbon adsorbent. The activation comprises oxidizing the surface of the carbon adsorbent with a mold oxidizing acid in the presence of a metal oxidation catalyst at an elevated temperature and boiling the mixture of the carbon adsorbent, mild oxidizing acid and metal oxidation catalyst to dryness. Then rinse the surface oxidized carbon adsorbent with water; and dry the rinsed surface oxidized carbon adsorbent.

  2. Activation of carbon dioxide on metal and metal oxide surfaces

    SciTech Connect

    Tan, C.D.; Chuang, S.S.C.

    1995-12-31

    The environmental concern about the impact of CO{sub 2} has grown recently due to its rapidly increasing concentration. Deforestation strongly affects the natural reduction of CO{sub 2} by water into carbohydrates by photosynthesis. Industrial utilization of CO{sub 2} by heterogeneous catalytic reactions can be one of the effective ways to cut the CO{sub 2} level. The first step in catalytic reaction of CO{sub 2} is the adsorption. The objective of this study is to investigate the adsorption of CO{sub 2} on the Rh/Al{sub 2}O{sub 3} surfaces. Rh is selected for this study because of its unique activity to catalyze a number of CO{sub 2} related reactions. In situ infrared results show that CO{sub 2} adsorbed on the alumina oxide support as bidentate carbonate and non-coordinated carbon which are the dominant species during the CO{sub 2} adsorption.

  3. Surface modification of activated carbons for CO 2 capture

    NASA Astrophysics Data System (ADS)

    Pevida, C.; Plaza, M. G.; Arias, B.; Fermoso, J.; Rubiera, F.; Pis, J. J.

    2008-09-01

    The reduction of anthropogenic CO 2 emissions to address the consequences of climate change is a matter of concern for all developed countries. In the short term, one of the most viable options for reducing carbon emissions is to capture and store CO 2 at large stationary sources. Adsorption with solid sorbents is one of the most promising options. In this work, two series of materials were prepared from two commercial activated carbons, C and R, by heat treatment with gaseous ammonia at temperatures in the 200-800 °C range. The aim was to improve the selectivity and capacity of the sorbents to capture CO 2, by introducing basic nitrogen-functionalities into the carbons. The sorbents were characterised in terms of texture and chemical composition. Their surface chemistry was studied through temperature-programmed desorption tests and X-ray photoelectron spectroscopy. The capture performance of the carbons was evaluated by using a thermogravimetric analyser to record mass uptakes by the samples when exposed to a CO 2 atmosphere.

  4. Preparation of high surface area activated carbon from coconut shells using microwave heating.

    PubMed

    Yang, Kunbin; Peng, Jinhui; Srinivasakannan, C; Zhang, Libo; Xia, Hongying; Duan, Xinhui

    2010-08-01

    The present study attempts to utilize coconut shell to prepare activated carbon using agents such as steam, CO(2) and a mixture of steam-CO(2) with microwave heating. Experimental results show that the BET surface area of activated carbons irrespective of the activation agent resulted in surface area in excess of 2000 m(2)/g. The activation time using microwave heating is very much shorter, while the yield of the activated carbon compares well with the conventional heating methods. The activated carbon prepared using CO(2) activation has the largest BET surface area, however the activation time is approximately 2.5 times higher than the activation using steam or mixture of steam-CO(2). The chemical structure of activated carbons examined using Fourier transformed infra-red spectra (FTIR) did not show any variation in the surface functional groups of the activated carbon prepared using different activation agents.

  5. High surface area activated carbon prepared from cassava peel by chemical activation.

    PubMed

    Sudaryanto, Y; Hartono, S B; Irawaty, W; Hindarso, H; Ismadji, S

    2006-03-01

    Cassava is one of the most important commodities in Indonesia, an agricultural country. Cassava is one of the primary foods in our country and usually used for traditional food, cake, etc. Cassava peel is an agricultural waste from the food and starch processing industries. In this study, this solid waste was used as the precursor for activated carbon preparation. The preparation process consisted of potassium hydroxide impregnation at different impregnation ratio followed by carbonization at 450-750 degrees C for 1-3 h. The results revealed that activation time gives no significant effect on the pore structure of activated carbon produced, however, the pore characteristic of carbon changes significantly with impregnation ratio and carbonization temperature. The maximum surface area and pore volume were obtained at impregnation ratio 5:2 and carbonization temperature 750 degrees C.

  6. 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.

  7. 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.

  8. 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.

  9. Ultrahigh surface area carbon from carbonated beverages. Combining self-templaing process and in situ activation

    DOE PAGES

    Zhang, Pengfei; Zhang, Zhiyong; Chen, Jihua; ...

    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

  10. Influence of activated carbon characteristics on toluene and hexane adsorption: Application of surface response methodology

    NASA Astrophysics Data System (ADS)

    Izquierdo, Mª Teresa; de Yuso, Alicia Martínez; Valenciano, Raquel; Rubio, Begoña; Pino, Mª Rosa

    2013-01-01

    The objective of this study was to evaluate the adsorption capacity of toluene and hexane over activated carbons prepared according an experimental design, considering as variables the activation temperature, the impregnation ratio and the activation time. The response surface methodology was applied to optimize the adsorption capacity of the carbons regarding the preparation conditions that determine the physicochemical characteristics of the activated carbons. The methodology of preparation produced activated carbons with surface areas and micropore volumes as high as 1128 m2/g and 0.52 cm3/g, respectively. Moreover, the activated carbons exhibit mesoporosity, ranging from 64.6% to 89.1% the percentage of microporosity. The surface chemistry was characterized by TPD, FTIR and acid-base titration obtaining different values of surface groups from the different techniques because the limitation of each technique, but obtaining similar trends for the activated carbons studied. The exhaustive characterization of the activated carbons allows to state that the measured surface area does not explain the adsorption capacity for either toluene or n-hexane. On the other hand, the surface chemistry does not explain the adsorption results either. A compromise between physical and chemical characteristics can be obtained from the appropriate activation conditions, and the response surface methodology gives the optimal activated carbon to maximize adsorption capacity. Low activation temperature, intermediate impregnation ratio lead to high toluene and n-hexane adsorption capacities depending on the activation time, which a determining factor to maximize toluene adsorption.

  11. Surface modification of activated carbon for enhanced adsorption of perfluoroalkyl acids from aqueous solutions.

    PubMed

    Zhi, Yue; Liu, Jinxia

    2016-02-01

    The objective of the research was to examine the effect of increasing carbon surface basicity on uptake of perfluorooctane sulfonic (PFOS) and carboxylic acids (PFOA) by activated carbon. Granular activated carbons made from coal, coconut shell, wood, and phenolic-polymer-based activated carbon fibers were modified through high-temperature and ammonia gas treatments to facilitate systematical evaluation of the impact of basicity of different origins. Comparison of adsorption isotherms and adsorption distribution coefficients showed that the ammonia gas treatment was more effective than the high-temperature treatment in enhancing surface basicity. The resultant higher point of zero charges and total basicity (measured by total HCl uptake) correlated with improved adsorption affinity for PFOS and PFOA. The effectiveness of surface modification to enhance adsorption varied with carbon raw material. Wood-based carbons and activated carbon fibers showed enhancement by one to three orders of magnitudes while other materials could experience reduction in adsorption towards either PFOS or PFOA.

  12. Surface heterogeneity effects of activated carbons on the kinetics of paracetamol removal from aqueous solution

    NASA Astrophysics Data System (ADS)

    Ruiz, B.; Cabrita, I.; Mestre, A. S.; Parra, J. B.; Pires, J.; Carvalho, A. P.; Ania, C. O.

    2010-06-01

    The removal of a compound with therapeutic activity (paracetamol) from aqueous solutions using chemically modified activated carbons has been investigated. The chemical nature of the activated carbon material was modified by wet oxidation, so as to study the effect of the carbon surface chemistry and composition on the removal of paracetamol. The surface heterogeneity of the carbon created upon oxidation was found to be a determinant in the adsorption capability of the modified adsorbents, as well as in the rate of paracetamol removal. The experimental kinetic data were fitted to the pseudo-second order and intraparticle diffusion models. The parameters obtained were linked to the textural and chemical features of the activated carbons. After oxidation the wettability of the carbon is enhanced, which favors the transfer of paracetamol molecules to the carbon pores (smaller boundary layer thickness). At the same time the overall adsorption rate and removal efficiency are reduced in the oxidized carbon due to the competitive effect of water molecules.

  13. 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...

  14. Influence of process parameters on the surface and chemical properties of activated carbon obtained from biochar by chemical activation.

    PubMed

    Angın, Dilek; Altintig, Esra; Köse, Tijen Ennil

    2013-11-01

    Activated carbons were produced from biochar obtained through pyrolysis of safflower seed press cake by chemical activation with zinc chloride. The influences of process variables such as the activation temperature and the impregnation ratio on textural and chemical-surface properties of the activated carbons were investigated. Also, the adsorptive properties of activated carbons were tested using methylene blue dye as the targeted adsorbate. The experimental data indicated that the adsorption isotherms are well described by the Langmuir equilibrium isotherm equation. The optimum conditions resulted in activated carbon with a monolayer adsorption capacity of 128.21 mg g(-1) and carbon content 76.29%, while the BET surface area and total pore volume corresponded to 801.5m(2)g(-1) and 0.393 cm(3)g(-1), respectively. This study demonstrated that high surface area activated carbons can be prepared from the chemical activation of biochar with zinc chloride as activating agents.

  15. IMPORTANCE OF ACTIVATED CARBON'S OXYGEN SURFACE FUNCTIONAL GROUPS ON ELEMENTAL MERCURY ADSORPTION

    EPA Science Inventory

    The effect of varying physical and chemical properties of activated carbons on adsorption of elemental mercury [Hg(0)] was studied by treating two activated carbons to modify their surface functional groups and pore structures. Heat treatment (1200 K) in nitrogen (N2), air oxidat...

  16. Decomposition degree of chlorofluorocarbon (CFC) and CFC replacements during recovery with surface-modified activated carbon

    SciTech Connect

    Tanada, Seiki; Kawasaki, Naohito; Nakamura, Takeo; Abe, Ikuo

    1996-02-10

    The recovery efficiency of 1,1,2-trichloro-1,2,2-trifluoroethane (CFC113) and three CFC replacements (1,1-dichloro-1-fluoroethane, HCFC141b; 1,3-dichloro-1,1,2,2,3-pentafluoro-propane, HCFC225cb; and 2,2,3,3,3-pentafluoro-1-propanol, 5FP) were investigated on the basis of their degree of decomposition and adsorption isotherms. The authors prepared activated carbons with various surface polarities to elucidate the recovery efficiency, the amount adsorbed, and the degree of decomposition. The amount of CFC113 adsorbed onto untreated activated carbon was the largest of all. That of HCFC225cb adsorbed onto activated carbon treated with hydrogen gas was larger than that adsorbed onto untreated activated carbon and activated carbon treated with 6 N nitric acid. The amount of 5FP and HCFC141b adsorbed on the various activated carbons was not substantial. The degree of decomposition of CFC replacements using the untreated activated carbon except for HCFC225cb was the largest of all. In the case without the activated carbon, that of CFC and the CFC replacements increased in the order 5FP, CFC113 or HCFC225cb, and HCFC141b. It is concluded that the recovery of CFC replacements was possible using the surface-modified activated carbons rather than the untreated activated carbon. The degree of decomposition of the CFC replacements during recovery using the activated carbon depends on the relationship between the adsorption site of the surface of the activated carbon and the polarity, hydrophilic site, or hydrophobic site of the CFC replacement molecule.

  17. [Surface characteristics of alkali modified activated carbon and the adsorption capacity of methane].

    PubMed

    Zhang, Meng-Zhu; Li, Lin; Liu, Jun-Xin; Sun, Yong-Jun; Li, Guo-Bin

    2013-01-01

    Coconut shell based activated carbon was modified by alkali with different concentrations. The surface structures of tested carbons were observed and analyzed by SEM and BET methods. Boehm's titration and SEM/EDS methods were applied to assay the functional groups and elements on the carbon surface. The adsorption of methane on tested carbons was investigated and adsorption behavior was described by the adsorption isotherms. Results showed that surface area and pore volume of modified carbon increased and surface oxygen groups decreased as the concentration of the alkali used increased, with no obvious change in pore size. When concentration of alkali was higher than 3.3 mol x L(-1), the specific surface area and pore volume of modified carbon was larger than that of original carbon. Methane adsorption capacity of alkali modified carbon increased 24%. Enlargement of surface area and pore volume, reduction of surface oxygen groups will benefit to enhance the methane adsorption ability on activated carbon. Adsorption behavior of methane followed the Langmuir isotherm and the adsorption coefficient was 163.7 m3 x mg(-1).

  18. [Preparation, characterization and adsorption performance of high surface area biomass-based activated carbons].

    PubMed

    Li, Kun-Quan; Li, Ye; Zheng, Zheng; Sang, Da-Zhi

    2013-01-01

    High surface area activated carbons were prepared with Spartina alterniflora and cotton stalk as raw materials and KOH as activating agent. Effects of materials type, impregnation ratio, activation temperature and heat preservation time on the yield, elemental composition and adsorptive capacity of activated carbon were studied. The properties and pore structure of the carbons were characterized with nitrogen adsorption, powder X-ray diffractometry (XRD), infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Main pore characteristics of activated carbons were analyzed by BET equation, Horvath-Kawazoe BET method and DFT method. The considerable preparation conditions are obtained as follows: impregnation ratio of 3: 1, an activation temperature of 800 degrees C and an activation time of 1.5 h. The BET surface area of activated carbon prepared from Spartina alterniflora reached 2 825 m2 x g(-1) when its total pore volume, yield, iodine number and methylene blue adsorption were 1.374 cm3 x g(-1), 16.36%, 1797 mg x g(-1) and 495 mg x g(-1) respectively under above conditions. The activated carbon from cotton stalk was prepared with BET surface area of 2 135 m2 x g(-1), total pore volume of 1.038 cm3 x g(-1), yield of 11.22%, methylene blue adsorption of 1 251 mg x g(-1), and iodine number of 478 mg x g(-1), respectively. The methylene blue adsorption and iodine number are much higher than the national first level for activated carbon. The Langmuir maximum adsorption capacities of 2,4-dinitrophenol on the two carbons were 932 mg x g(-1) and 747 mg x g(-1), respectively, which are superior to ordinary activated carbon and activated carbon fiber.

  19. Carbon activation process for increased surface accessibility in electrochemical capacitors

    DOEpatents

    Doughty, Daniel H.; Eisenmann, Erhard T.

    2001-01-01

    A process for making carbon film or powder suitable for double capacitor electrodes having a capacitance of up to about 300 F/cm.sup.3 is disclosed. This is accomplished by treating in aqueous nitric acid for a period of about 5 to 15 minutes thin carbon films obtained by carbonizing carbon-containing polymeric material having a high degree of molecular directionality, such as polyimide film, then heating the treated carbon film in a non-oxidizing atmosphere at a non-graphitizing temperature of at least 350.degree. C. for about 20 minutes, and repeating alternately the nitric acid step and the heating step from 7 to 10 times. Capacitors made with this carbon may find uses ranging from electronic devices to electric vehicle applications.

  20. Activation and splitting of carbon dioxide on the surface of an inorganic electride material.

    PubMed

    Toda, Yoshitake; Hirayama, Hiroyuki; Kuganathan, Navaratnarajah; Torrisi, Antonio; Sushko, Peter V; Hosono, Hideo

    2013-01-01

    Activation of carbon dioxide is the most important step in its conversion into valuable chemicals. Surfaces of stable oxide with a low work function may be promising for this purpose. Here we report that the surfaces of the inorganic electride [Ca24Al28O64](4+)(e(-))4 activate and split carbon dioxide at room temperature. This behaviour is attributed to a high concentration of localized electrons in the near-surface region and a corrugation of the surface that can trap oxygen atoms and strained carbon monoxide and carbon dioxide molecules. The [Ca24Al28O64](4+)(e(-))4 surface exposed to carbon dioxide is studied using temperature-programmed desorption, and spectroscopic methods. The results of these measurements, corroborated with ab initio simulations, show that both carbon monoxide and carbon dioxide adsorb on the [Ca24Al28O64](4+)(e(-))4 surface at RT and above and adopt unusual configurations that result in desorption of molecular carbon monoxide and atomic oxygen upon heating.

  1. Process effects on activated carbon with large specific surface area from corn cob.

    PubMed

    Cao, Qing; Xie, Ke-Chang; Lv, Yong-Kang; Bao, Wei-Ren

    2006-01-01

    The main factors that affect the large specific surface area (SSA) of the activated carbon from agricultural waste corn cobs were studied by chemically activated method with solution of KOH and soap which acted as surfactant. The experiment showed that not only the activation temperature, activation time and the mass ratio of KOH to the carbonized material, but also the activated methods using activator obviously influenced the SSA of activated carbon. The experimental operating conditions were as follows: the carbonized temperature being 450 degrees C and keeping time being 4 h using N2 as protective gas; the activation temperature being 850 degrees C and holding time being 1.2 h; the mass ratio of KOH to carbonized material being 4.0; the time of soaking carbonized material in the solution of KOH and soap being 30 min. Under the optimal conditions, the SSA of activated carbon from corn cobs reached 2700 m2/g. And the addition of the soap as surfactant may shorten the soaking time. The structure of the activated carbon prepared had narrow distribution of pore size and the micro-pores accounted for 78%. The advantages of the method described were easy and feasible.

  2. Impact of carbon on the surface and activity of silica-carbon supported copper catalysts for reduction of nitrogen oxides

    NASA Astrophysics Data System (ADS)

    Spassova, I.; Stoeva, N.; Nickolov, R.; Atanasova, G.; Khristova, M.

    2016-04-01

    Composite catalysts, prepared by one or more active components supported on a support are of interest because of the possible interaction between the catalytic components and the support materials. The supports of combined hydrophilic-hydrophobic type may influence how these materials maintain an active phase and as a result a possible cooperation between active components and the support material could occur and affects the catalytic behavior. Silica-carbon nanocomposites were prepared by sol-gel, using different in specific surface areas and porous texture carbon materials. Catalysts were obtained after copper deposition on these composites. The nanocomposites and the catalysts were characterized by nitrogen adsorption, TG, XRD, TEM- HRTEM, H2-TPR, and XPS. The nature of the carbon predetermines the composite's texture. The IEPs of carbon materials and silica is a force of composites formation and determines the respective distribution of the silica and carbon components on the surface of the composites. Copper deposition over the investigated silica-carbon composites leads to formation of active phases in which copper is in different oxidation states. The reduction of NO with CO proceeds by different paths on different catalysts due to the textural differences of the composites, maintaining different surface composition and oxidation states of copper.

  3. Mesopore control of high surface area NaOH-activated carbon.

    PubMed

    Tseng, Ru-Ling

    2006-11-15

    Activated carbon with BET surface areas in a narrow range from 2318 to 2474 m2/g was made by soaking the char made from corncob in a concentrated NaOH solution at NaOH/char ratios from 3 to 6; the mesopore volumes of the activated carbon were significantly changed from 21 to 58%. The relationships between pore properties (Sp, Vpore, Vmicro/Vpore, Dp) and NaOH dosage were investigated. Comparisons between the methods of NaOH and KOH activation revealed that NaOH activation can suitably control the mesopore specific volume of the activated carbon. Elemental analysis revealed that the H/C and O/C values of the activated carbons of NaOH/char ratios from 3 to 6 were significantly lower. SEM observation of surface hole variation of the activated carbon ascertained that the reaction process was inner pore etching. Based on the above three measurements and experimental investigations, the assumption made by previous researchers, namely that NaOH and KOH produce similar results, was challenged. Furthermore, the adsorption kinetics was used to investigate the adsorption rate of an Elovich equation to determine the relationships between the adsorption behavior on larger molecules (dyes) and smaller molecules (phenols) and the pore structure of the activated carbon.

  4. Tailoring the surface chemistry of activated carbon cloth by electrochemical methods.

    PubMed

    Tabti, Zakaria; Ruiz-Rosas, Ramiro; Quijada, César; Cazorla-Amorós, Diego; Morallón, Emilia

    2014-07-23

    This paper presents a systematic study of the effect of the electrochemical treatment (galvanostatic electrolysis in a filter-press electrochemical cell) on the surface chemistry and porous texture of commercial activated carbon cloth. The same treatments have been conducted over a granular activated carbon in order to clarify the effect of morphology. The influence of different electrochemical variables, such as the electrode polarity (anodic or cathodic), the applied current (between 0.2 and 1.0 A) and the type of electrolyte (HNO3 and NaCl) have also been analyzed. The anodic treatment of both activated carbons causes an increase in the amount of surface oxygen groups, whereas the cathodic treatment does not produce any relevant modification of the surface chemistry. The HNO3 electrolyte produced a lower generation of oxygen groups than the NaCl one, but differences in the achieved distribution of surface groups can be benefitial to selectively tune the surface chemistry. The porous texture seems to be unaltered after the electro-oxidation treatment. The validity of this method to introduce surface oxygen groups with a pseudocapacitive behavior has been corroborated by cyclic voltammetry. As a conclusion, the electrochemical treatment can be easily implemented to selectively and quantitatively modify the surface chemistry of activated carbons with different shapes and morphologies.

  5. Adsorption characteristics of N-nitrosodimethylamine from aqueous solution on surface-modified activated carbons.

    PubMed

    Dai, Xiaodong; Zou, Linda; Yan, Zifeng; Millikan, Mary

    2009-08-30

    This study investigated the removal of N-nitrosodimethylamine (NDMA) by an adsorption mechanism using commercially available activated carbons and surface-modified activated carbons. The effects of the modification on the properties of the activated carbon were studied by N(2) adsorption/desorption, Diffuse Reflectance Infrared Fourier Transmission (DRIFT) analysis and X-Ray Photoelectron Spectroscopy (XPS). Adsorption experiments revealed that the activated carbons demonstrated a greater capacity for NDMA adsorption capacity than can be achieved using zeolite. The equilibrium data was fitted to the Freundlich equation and it was found that the adsorption capacity was significantly influenced by the micropore size, relative pore volume and surface characteristics. Adsorption experiments were conducted using unmodified and modified activated carbons. The results indicated that the adsorption capacity of NDMA can be significantly improved by heat treatment and doping of TiO(2) particles. This was because the surface treatments yielded more hydrophobic sites and fewer oxygen-containing surface functional groups, and consequently an increased capacity for NDMA adsorption.

  6. Surface modification of coconut shell based activated carbon for the improvement of hydrophobic VOC removal.

    PubMed

    Li, Lin; Liu, Suqin; Liu, Junxin

    2011-08-30

    In this study, coconut shell based carbons were chemically treated by ammonia, sodium hydroxide, nitric acid, sulphuric acid, and phosphoric acid to determine suitable modification for improving adsorption ability of hydrophobic volatile organic compounds (VOCs) on granular activated carbons (GAC). The saturated adsorption capacities of o-xylene, a hydrophobic volatile organic compound, were measured and adsorption effects of the original and modified activated carbons were compared. Results showed that GAC modified by alkalis had better o-xylene adsorption capacity. Uptake amount was enhanced by 26.5% and reduced by 21.6% after modification by NH(3)H(2)O and H(2)SO(4), respectively. Compared with the original, GAC modified by acid had less adsorption capacity. Both SEM/EDAX and BET were used to identify the structural characteristics of the tested GAC, while IR spectroscopy and Boehm's titration were applied to analysis the surface functional groups. Relationships between physicochemical characteristics of GAC and their adsorption performances demonstrated that o-xylene adsorption capacity was related to surface area, pore volume, and functional groups of the GAC surface. Removing surface oxygen groups, which constitute the source of surface acidity, and reducing hydrophilic carbon surface favors adsorption capacity of hydrophobic VOCs on carbons. The performances of modified GACs were also investigated in the purification of gases containing complex components (o-xylene and steam) in the stream.

  7. High surface area porous carbons prepared from hydrochars by phosphoric acid activation.

    PubMed

    Wang, Lili; Guo, Yupeng; Zou, Bo; Rong, Chunguang; Ma, Xiaoyu; Qu, Yuning; Li, Ying; Wang, Zichen

    2011-01-01

    In the present work, a new route for preparation of high-performance porous carbons under mild conditions was reported. The high surface area (2700 m2/g) and large pore volume (1.98 cm3/g) porous carbons were prepared from hydrochars by conventional phosphoric acid activation method. The hydrochars described here can be obtained from sulfuric acid hydrolysis of rice husk via dehydration, polymerization and carbonization. A specific capacitance of 130 F g(-1) was achieved by using the porous carbon, indicating that the porous carbon prepared by this route has good electrochemical performance. Furthermore, the localized graphitic nature of the porous carbon was proved by X-ray diffraction pattern.

  8. Effect of Activating Agent on the Preparation of Bamboo-Based High Surface Area Activated Carbon by Microwave Heating

    NASA Astrophysics Data System (ADS)

    Xia, Hongying; Wu, Jian; Srinivasakannan, Chandrasekar; Peng, Jinhui; Zhang, Libo

    2016-06-01

    The present work attempts to convert bamboo into a high surface area activated carbon via microwave heating. Different chemical activating agents such as KOH, NaOH, K2CO3 and Na2CO3 were utilized to identify a most suitable activating agent. Among the activating agents tested KOH was found to generate carbon with the highest porosity and surface area. The effect of KOH/C ratio on the porous nature of the activated carbon has been assessed. An optimal KOH/C ratio of 4 was identified, beyond which the surface area as well as the pore volume were found to decrease. At the optimized KOH/C ratio the surface area and the pore volume were estimated to be 3,441 m2/g and 2.093 ml/g, respectively, with the significant proportion of which being microporous (62.3%). Activated carbon prepared under the optimum conditions was further characterized using Fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM). Activated carbons with so high surface area and pore volume are very rarely reported, which could be owed to the nature of the precursor and the optimal conditions of mixture ratio adopted in the present work.

  9. Effects of nitrogen plasma treatment on the surface characteristics of olive stone-based activated carbon.

    PubMed

    Soudani, Nouha; Najar-Souissi, Souad; Abderkader-Fernandez, Victor K; Ouederni, Abdelmottalab

    2017-04-01

    Nitrogen plasma treatment (NPT) of activated carbon (AC) at different conditions was carried out to introduce nitrogen-containing groups onto olive stone-activated carbon (OSAC) surfaces. Textural characteristics of raw and irradiated samples were analyzed by N2 and CO2 adsorption. Surface chemical functional groups were analyzed by X-ray photoelectron spectrometry (XPS) and Fourier Transformed Infrared spectroscopy. The results showed that after NPT, the surface textural properties of irradiated OSAC were slightly damaged, and a gradual decrease in surface area and pore volume was observed during the irradiation. XPS revealed that NPT could change the distribution of oxygen functional groups on the OSAC surface and there were more nitrogen atoms incorporated into the aromatic ring. A tentative explanation for the modification process is proposed. Phenol adsorption was enhanced from 110 mg/g for untreated AC to 635 mg/g for 30-min plasma-treated OSAC.

  10. The recovery of chlorofluorocarbons and chlorofluorocarbon replacements by surface modified activated carbon

    SciTech Connect

    Kawasaki, Naohito; Tanada, Seiki; Nakamura, Takeo; Abe, Ikuo

    1995-06-15

    The adsorption properties of chlorofluorocarbon CFC113 and CFC replacements (HCFC225cb and 5FP) on activated carbon treated with 6 N nitric acid or hydrogen gas were investigated on the basis of their physicochemical adsorption isotherm and Dubinin-Rudshkevich plot to elucidate the difference between untreated activated carbon (U-AC) and surface modified activated carbon (NT-AC and HT-AC) during interaction with CFCs and CFC replacements. No correlation between the physicochemical properties of the activated carbon surface and the polarity of CFCs or CFC replacements was observed. The adsorption isotherms of CFC113, HCFC225cb, and 5FP on U-AC, NT-AC, and HT-AC have different branch points, that is, selective adsorption (HT-AC) and nonselective adsorption (NT-AC). NT-AC is well suited for the recovery of a mixture of CFCs and CFC replacements, while HT-AC is good for a sample of CFC replacements. Studying the adsorption rate is useful for increasing the recovery efficiency. Therefore, the rate of adsorption of CFCs and CFC replacements onto surface modified activated carbon was investigated. The Sameshima equation fits the adsorption isotherms. The initial rate constants k for CFC113, HCFC225cb, and 5FP onto U-AC, HT-AC, and HT-AC, respectively, were the largest. HT-AC could be adapted for the recover of HCFC225cb and 5FP.

  11. High surface area microporous activated carbons prepared from Fox nut (Euryale ferox) shell by zinc chloride activation

    NASA Astrophysics Data System (ADS)

    Kumar, Arvind; Mohan Jena, Hara

    2015-11-01

    High surface area microporous activated carbon has been prepared from Fox nutshell (Euryale ferox) by chemical activation with ZnCl2 as an activator. The process has been conducted at different impregnation (ZnCl2/Fox nutshell) ratios (1-2.5) and carbonization temperatures (500-700 °C). The thermal decomposition behavior of Fox nutshell and impregnated Fox nutshell has been carried out by thermogravimetric analysis. The pore properties including the BET surface area, micropore surface area, micropore volume, and pore size distribution of the activated carbons have been determined by nitrogen adsorption-desorption isotherms at -196 °C using the BET, t-plot method, DR, and BJH methods. The BET surface area, the microporous surface area, total pore volume, and micropore volume have been obtained as 2869 m2/g, 2124 m2/g, 1.96 cm3/g, and 1.68 cm3/g, respectively, and the microporosity percentage of the prepared activated carbon is 85.71%. The prepared activated carbons have been also characterized with instrumental methods such as Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and field emission scanning electron microscopy (FESEM).

  12. Preparation and characterization of high-specific-surface-area activated carbons from K2CO3-treated waste polyurethane.

    PubMed

    Hayashi, J; Yamamoto, N; Horikawa, T; Muroyama, K; Gomes, V G

    2005-01-15

    An activated carbon with high specific surface area was prepared from polyurethane foam by chemical activation with K2CO3 and the influences of carbonization temperature and impregnation ratio on the pore structure of the prepared activated carbon were investigated. It was found that the specific surface area of the activated carbon was at a maximum value (about 2800 m(2)/g) at a carbonization temperature of 1073 K and at an impregnation ratio of 1.0. It was concluded that the polyurethane foam structure was modified during impregnation by K2CO3, K2CO3 promoted charring during carbonization, and then the weight loss behavior was changed below 700 and above 1000 K, carbon in the char was consumed by K2CO3 reduction, and this led to the high specific surface area. The prepared activated carbon had a very sharp micropore size distribution, compared with the commercial activated carbon having high specific surface area. The amounts of three organic vapors (benzene, acetone, and octane) adsorbed on the prepared activated carbons was much larger than those on the traditional coconut shell AC and the same as those on the commercial activated carbon except for octane. We surmised that the high specific surface area was due to the modification of the carbonization behavior of polyurethane foam by K2CO3.

  13. N-nitrosamines formation from secondary amines by nitrogen fixation on the surface of activated carbon.

    PubMed

    Padhye, Lokesh P; Hertzberg, Benjamin; Yushin, Gleb; Huang, Ching-Hua

    2011-10-01

    Our previous study demonstrated that many commercial activated carbon (AC) particles may catalyze transformation of secondary amines to yield trace levels of N-nitrosamines under ambient aerobic conditions. Because of the widespread usage of AC materials in numerous analytical and environmental applications, it is imperative to understand the reaction mechanism responsible for formation of nitrosamine on the surface of ACs to minimize their occurrence in water treatment systems and during analytical methods employing ACs. The study results show that the AC-catalyzed nitrosamine formation requires both atmospheric oxygen and nitrogen. AC's surface reactive sites react with molecular oxygen to form reactive oxygen species (ROS), which facilitate fixation of molecular nitrogen on the carbon surfaces to generate reactive nitrogen species (RNS) likely nitrous oxide and hydroxylamine that can react with adsorbed amines to form nitrosamines. AC's properties play a crucial role as more nitrosamine formation is associated with carbon surfaces with higher surface area, more surface defects, reduced surface properties, higher O(2) uptake capacity, and higher carbonyl group content. This study is a first of its kind on the nitrosamine formation mechanism involving nitrogen fixation on AC surfaces, and the information will be useful for minimization of nitrosamines in AC-based processes.

  14. Adsorption of cadmium ions on oxygen surface sites in activated carbon

    SciTech Connect

    Jia, Y.F.; Thomas, K.M.

    2000-02-08

    Various types of oxygen functional groups were introduced onto the surface of coconut shell derived activated carbon by oxidation using nitric acid. Fourier-transform infrared spectroscopy (FTIR), temperature-programmed desorption (TPD), and selective neutralization were used to characterize the surface oxygen functional groups. The oxidized carbons were also heat treated to provide a suite of carbons where the oxygen functional groups of various thermal stabilities were varied progressively. The adsorption of cadmium ions was enhanced dramatically by oxidation of the carbon. The ratio of released protons to adsorbed cadmium ions on oxidized carbon was approximately 2, indicating cation exchange was involved in the process of adsorption. Na{sup +} exchange studies with the oxidized carbon gave a similar ratio. After heat treatment of the oxidized carbons to remove oxygen functional groups, the ratio of H{sup +} released to Cd{sup 2+} adsorbed and the adsorption capacity decreased significantly. Both reversible and irreversible processes were involved in cadmium ion adsorption with reversible adsorption having higher enthalpy. The irreversible adsorption resulted from cation exchange with carboxylic acid groups, whereas the reversible adsorption probably involved physisorption of the partially hydrated cadmium ion.

  15. Initial heats of H{sub 2}S adsorption on activated carbons: Effect of surface features

    SciTech Connect

    Bagreev, A.; Adib, F.; Bandosz, T.J.

    1999-11-15

    The sorption of hydrogen sulfide was studied on activated carbons of various origins by means of inverse gas chromatography at infinite dilution. The conditions of the experiment were dry and anaerobic. Prior to the experiments the surface of some carbon samples was oxidized using either nitric acid or ammonium persulfate. Then the structural parameters of carbons were evaluated from the sorption of nitrogen. From the IGC experiments at various temperatures, heats of adsorption were calculated. The results showed that the heat of H{sub 2}S adsorption under dry anaerobic conditions does not depend on surface chemistry. The dependence of the heat of adsorption on the characteristic energy of nitrogen adsorption calculated from the Dubinin-Raduskevich equation was found. This correlation can be used to predict the heat of H{sub 2}S adsorption based on the results obtained from nitrogen adsorption.

  16. Surface Properties and Catalytic Performance of Activated Carbon Fibers Supported TiO2 Photocatalyst

    NASA Astrophysics Data System (ADS)

    Yang, Huifen; Fu, Pingfeng

    Activated carbon fibers supported TiO2 photocatalyst (TiO2/ACF) in felt-form was successfully prepared with a dip-coating process using organic silicon modified acrylate copolymer as a binder followed by calcination at 500°C in a stream of Ar gas. The photocatalyst was characterized by SEM, XRD, XPS, FTIR, and BET surface area. Most of carbon fibers were coated with uniformly distributed TiO2 clusters of nearly 100 nm. The loaded TiO2 layer was particulate for the organic binder in the compact film was carbonized. According to XPS and FTIR analysis, amorphous silica in carbon grains was synthesized after carbonizing organic silicon groups, and the Ti-O-Si bond was formed between the interface of loaded TiO2 and silica. Additionally, the space between adjacent carbon fibers still remained unfilled after TiO2 coating, into which both UV light and polluted solutions could penetrate to form a three-dimensional environment for photocatalytic reactions. While loaded TiO2 amount increased to 456 mg TiO2/1 g ACF, the TiO2/ACF catalyst showed its highest photocatalytic activity, and this activity only dropped about 10% after 12 successive runs, exhibiting its high fixing stability of coated TiO2.

  17. Energy storage on ultrahigh surface area activated carbon fibers derived from PMIA.

    PubMed

    Castro-Muñiz, Alberto; Suárez-García, Fabián; Martínez-Alonso, Amelia; Tascón, Juan M D; Kyotani, Takashi

    2013-08-01

    High-performance carbon materials for energy storage applications have been obtained by using poly(m-phenylene isophthalamide), PMIA, as a precursor through the chemical activation of the carbonized aramid fiber by using KOH. The yield of the process of activation was remarkably high (25-40 wt%), resulting in activated carbon fibers (ACFs) with ultrahigh surface areas, over 3000 m(2) g(-1) , and pore volumes exceeding 1.50 cm(3) g(-1) , keeping intact the fibrous morphology. The porous structure and the surface chemical properties could easily be controlled through the conditions of activation. The PMIA-derived ACFs were tested in two types of energy storage applications. At -196 °C and 1 bar, H2 uptake values of approximately 3 t% were obtained, which, in combination with the textural properties, rendered it a good candidate for H2 adsorption at high pressure and temperature. The performance of the ACFs as electrodes for electrochemical supercapacitors was also investigated. Specific capacitance values between 297 and 531 g(-1) at 50 mA g(-1) were obtained in aqueous electrolyte (1 H2 SO4 ), showing different behaviors depending on the surface chemical properties.

  18. Role of the surface chemistry of activated carbons in dye removal from aqueous solution

    NASA Astrophysics Data System (ADS)

    Zhou, Hua-lei; Zhen, Wen-juan; Zhu, Qian; Wu, Xiao-bin; Chang, Zhi-dong; Li, Wen-jun

    2015-07-01

    Commercial activated carbons were modified by a series of chemical or physical treatments using H2O2, NH3, and heating under N2 flow without notably changing their pore structures. The resultant carbons were characterized by N2 adsorption and Bohem titration and then used to remove Ponceau 4R, methyl orange and brilliant blue from aqueous solutions. Surface chemistry was found to play a significantly different role in removing these three compounds. The removal of anionic Ponceau 4R increases with increasing carbon surface basicity due to the predominant dispersive interaction mechanism. In contrast, surface chemistry has little effect on the removal of anionic methyl orange, which can be explained by two parallel mechanisms involving electrostatic and dispersive interactions due to the basic amine group in a dye molecule. The influence of surface chemistry on the removal of amphoteric brilliant blue dye can also be ignored due to a weak interaction between the carbons and dye molecules, which is resulted from strong cohesive energy from electrostatic forces inside amphoteric dye molecules.

  19. Utilization of zinc chloride for surface modification of activated carbon derived from Jatropha curcas L. for absorbent material.

    PubMed

    Pratumpong, P; Toommee, S

    2016-12-01

    The objective of this research is to produce the low-cost activated carbon from Jatropha curcas L. by chemical activation using zinc chloride ZnCl2. The effects of the impregnation ratio on the surface and chemical properties of activated carbon were investigated. The impregnation ratio was selected at the range of 1:1-10:1 for investigation. The optimum conditions resulted in an activated carbon with a carbon content of 80% wt, while the specific surface area evaluated using nitrogen adsorption isotherm corresponds to 600 m(2)/g.

  20. Influence of surface modification on catalytic activity of activated carbon toward decomposition of hydrogen peroxide and 2-chlorophenol.

    PubMed

    Huang, Hsu-Hui; Lu, Ming-Chun; Chen, Jong-Nan; Lee, Cheng-Te

    2003-07-01

    The objective of this research was to investigate the influence of the activated carbons modified by chemical treatment on the surface catalyzed loss of H2O2 and 2-CP. The characteristics of the modified activated carbons were examined by several techniques including nitrogen adsorption, SEM, and EDS. The H2O2 decomposition rate would be suppressed significantly either by the change of surface properties modified with chemical treatment or the reduction of active sites occupied with the adsorption of 2-CP. In addition, the H2O2 decomposition rate with activated carbons within a specific time can be described by a second-order kinetic expression with respect to the concentration of GAC and H2O2 in the absence or presence of 2-CP. The catalytic activities of the three activated carbons toward 2-CP reduction followed the inverse sequence of those toward H2O2 loss, implying that acidic surface functional group could retard the H2O2 loss and reduce the effect of surface scavenging resulting in increasing the reduction efficiency of 2-CP. By the detection of chloride ions in reaction mixture, it can be demonstrated that the reduction of 2-CP was not only attributed to the advanced adsorption but also the oxidation of the 2-CP with effective radicals. The real oxidation efficiency of 2-CP for the activated carbon modified with hot nitric acid was observed between 0.04 and 0.01 (mol/mol), offering a comparable efficiency to that of the other oxidation system using metal oxide as catalyst.

  1. Effect of surface characteristics of wood-based activated carbons on adsorption of hydrogen sulfide

    SciTech Connect

    Adib, F.; Bagreev, A.; Bandosz, T.J.

    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 H{sub 2}S 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.

  2. 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).

  3. Interactions of water, methanol and diethyl ether molecules with the surface of oxidized activated carbon

    NASA Astrophysics Data System (ADS)

    Salame, Issa I.; Bandosz, Teresa J.

    Two samples of oxidized activated carbon of wood origin were used as adsorbents of water, methanol, and diethyl ether. Structural and chemical characteristics of the samples' surfaces were obtained using adsorption of nitrogen and Boehm titration. The adsorption isotherms of water and methanol were measured using a volumetric apparatus whereas the adsorption of diethyl ether was studied by means of inverse gas chromatography at finite concentration. Then the isotherms at three different temperatures were used to calculate the isosteric heats of adsorption. The results showed that the strength of interaction depends on the porosity of the sample and its surface chemistry. The effect of surface chemistry and the presence of oxygenated groups are predominant in the case of water and the least important in the case of diethyl ether. This is the result of the chemical nature of the molecules, their sizes, and the relative strengths of the dispersive interactions in small pores in comparison with hydrogen bonding to surface functional groups.

  4. Effect of Microwave Heating Conditions on the Preparation of High Surface Area Activated Carbon from Waste Bamboo

    NASA Astrophysics Data System (ADS)

    Wu, Jian; Hongying Xia; Zhang, Libo; Xia, Yi; Peng, Jinhui; Wang, Shixing; Zheng, Zhaoqiang; Zhang, Shengzhou

    2015-11-01

    The present study reports the effect of microwave power and microwave heating time on activated carbon adsorption ability. The waste bamboo was used to preparing high surface area activated carbon via microwave heating. The bamboo was carbonized for 2 h at 600°C to be used as the raw material. According to the results, microwave power and microwave heating time had a significant impact on the activating effect. The optimal KOH/C ratio of 4 was identified when microwave power and microwave heating time were 700 W and 15 min, respectively. Under the optimal conditions, surface area was estimated to be 3441 m2/g with pore volume of 2.093 ml/g and the significant proportion of activated carbon was microporous (62.3%). The results of Fourier transform infrared spectroscopy (FTIR) were illustrated that activated carbon surface had abundant functional groups. Additionally the pore structure is characterized using Scanning Electron Microscope (SEM).

  5. Preparation and characterization of high surface area activated carbon from Fox nut (Euryale ferox) shell by chemical activation with H3PO4

    NASA Astrophysics Data System (ADS)

    Kumar, Arvind; Jena, Hara Mohan

    Activated carbons were prepared from Fox nutshell by chemical activation with H3PO4 in N2 atmosphere and their characteristics were studied. The effects of activation temperature and impregnation ratio were examined. N2 adsorption isotherms characterized the surface area, total pore volume, micropore volume and pore size distribution of activated carbons. Activated carbon was produced at 700 °C with a 1.5 impregnation ratio and one hour of activation time has found 2636 m2/g and 1.53 cm3/g of highest BET surface area and total pore volume, respectively. The result of Fourier-infrared spectroscopy analysis of the prepared activated carbon confirmed that the carbon has abundant functional groups on the surface. Field emission scanning electron micrographs of the prepared activated carbon showed that a porous structure formed during activation.

  6. Surface Alteration of Activated Carbon for Detoxification of Copper (ii) from Industrial Effluents

    NASA Astrophysics Data System (ADS)

    Bhutto, Sadaf; Khan, M. Nasiruddin

    2013-04-01

    The low-cost modified activated carbons were prepared from Thar and Lakhra (Pakistan) coals by activation with sulfuric acid and further modified with citric, tartaric and acetic acids for the selective adsorption of Cu(II) from aqueous solution. The original carbon obtained from activated Thar and Lakhra coals at pH 3.0 displayed significant adsorption capacity for lead and insignificant capacity values (0.880 and 0.830 mgṡg-1) for copper. However, after modification with citric, tartaric and acetic acid the copper adsorption capacities enhanced in the range of 5.56-21.85 and 6.05-44.61 times, respectively. The Langmuir, Freundlich and Temkin adsorption isotherms were used to elucidate the observed sorption phenomena. The isotherm equilibrium data was well fitted by the Langmuir and sufficiently fitted to the Freundlich models. The calculated thermodynamic parameters such as change in Gibbs free energy (ΔG°), enthalpy (ΔH°) and entropy (ΔS°) inferred that the investigated adsorption was spontaneous and endothermic in nature. Based on the results, it was concluded that the surface alteration with citric and tartaric acid, Thar and Lakhra activated carbons had significant potential for selective removal of copper(II) from industrial wastewater.

  7. The effect of activated carbon support surface modification on characteristics of carbon nanospheres prepared by deposition precipitation of Fe-catalyst

    NASA Astrophysics Data System (ADS)

    Kristianto, H.; Arie, A. A.; Susanti, R. F.; Halim, M.; Lee, J. K.

    2016-11-01

    In this study the effect of activated carbon support modification to synthesis of CNSs was observed. Modification of activated carbon was done by using nitric acid. The effect of modification was analyzed from its FTIR spectra. The Fe catalysts were deposited on to the support by using urea deposition precipitation method at various initial catalysts concentration. CNSs was synthesized by utilizing cooking palm oil as renewable carbon source, and pyrolized at 700°C for 1 hour under nitrogen atmosphere. The products obtained then analyzed using SEM-EDS, TEM, XRD, and Raman spectroscopy. The modification of activated carbon support had increased the oxygen functional group. This increase resulted on increase of metal catalysts deposited on activated carbon surface. Peak of C (100) was observed, while ID/IG of samples were obtained around 0.9, which is commonly obtained for CNSs. High catalysts loading on modified activated carbon support caused decomposition of CNSs and formation carbon onion.

  8. Effect of surface acidic oxides of activated carbon on adsorption of ammonia.

    PubMed

    Huang, Chen-Chia; Li, Hong-Song; Chen, Chien-Hung

    2008-11-30

    The influence of surface acidity of activated carbon (AC) was experimentally studied on adsorption of ammonia (NH(3)). Coconut shell-based AC was modified by various acids at different concentrations. There were five different acids employed to modified AC, which included nitric acid, sulfuric acid, hydrochloric acid, phosphoric acid, and acetic acid. Acidic functional groups on the surface of ACs were determined by a Fourier transform infrared spectrograph (FTIR) and by the Boehm titration method. Specific surface area and pore volume of the ACs were measured by a nitrogen adsorption apparatus. Adsorption amounts of NH(3) onto the ACs were measured by a dynamic adsorption system at room temperature according to the principle of the ASTM standard test method. The concentration of NH(3) in the effluent stream was monitored by a gas-detecting tube technique. Experimental results showed that adsorption amounts of NH(3) on the modified ACs were all enhanced. The ammonia adsorption amounts on various activated carbons modified by different acids are in the following order: nitric acid>sulfuric acid>acetic acid approximately phosphoric acid>hydrochloric acid. It is worth to note that the breakthrough capacity of NH(3) is linearly proportional to the amount of acidic functional groups of the ACs.

  9. Effect of surface property of activated carbon on adsorption of nitrate ion.

    PubMed

    Iida, Tatsuya; Amano, Yoshimasa; Machida, Motoi; Imazeki, Fumio

    2013-01-01

    In this study, the removal of acidic functional groups and introduction of basic groups/sites on activated carbons (ACs) by outgassing and ammonia gas treatment were respectively carried out to enhance the nitrate ion adsorption in aqueous solution. Then, the relationships between nitrate ion adsorption and solution pH as well as surface charge of AC were investigated to understand the basic mechanisms of nitrate ion adsorption by AC. The result showed that the nitrate ion adsorption depended on the equilibrium solution pH (pHe) and the adsorption amount was promoted with decreasing pHe. The ACs treated by outgassing and ammonia gas treatment showed larger amount of nitrate ion adsorption than that by untreated AC. These results indicated that, since basic groups/sites could adsorb protons in the solution, the AC surface would be charged positively, and that the nitrate ion would be electrically interacted with positively charged carbon surface. Accordingly, it was concluded that basic groups/sites on the surface of AC could promote nitrate ion adsorption.

  10. Surface functional characteristics (C, O, S) of waste tire-derived carbon black before and after steam activation.

    PubMed

    Lin, Hsun-Yu; Chen, Wei-Chin; Yuan, Chung-Shin; Hung, Chung-Hsuang

    2008-01-01

    The effects of steam activation on the surface functional characteristics of waste tire-derived carbon black were investigated. Two carbon-based materials, powdered carbon black (PCB) and PCB-derived powdered activated carbon (PCB-PAC), were selected for this study. A stainless steel tubular oven was used to activate the PCB at an activation temperature of 900 degrees C and 1 atm using steam as an activating reagent. X-ray photoelectron spectroscopy (XPS) was adopted to measure the surface composition and chemical structure of carbon surface. Various elemental spectra (C, O, and S) of each carbon sample were further deconvoluted by peak synthesis. Results showed that the surfaces of PCB and PCB-PAC consisted mainly of C-C and C-O. The PCB-PAC surface had a higher percentage of oxygenated functional groups (C=O and O-C=O) than PCB. The O1s spectra show that the oxygen detected on the PCB surface was mainly bonded to carbon (C-O), whereas the oxygen on the PCB-PAC surface could be bonded to hydrogen (O-H) and carbon (C-O). Sulfur on the surface of PCB consisted of 58.9 wt% zinc sulfide (ZnS) and 41.1 wt% S=C=S, whereas that on the surfaces of PCB-PAC consisted mainly of S=C=S. Furthermore, the increase of oxygen content from 9.6% (PCB) to 11.9% (PCB-PAC) resulted in the increase of the pH values of PCB-PAC after steam activation.

  11. Surface activated carbon nanospheres for fast adsorption of silver ions from aqueous solutions.

    PubMed

    Song, Xianghua; Gunawan, Poernomo; Jiang, Rongrong; Leong, Susanna Su Jan; Wang, Kean; Xu, Rong

    2011-10-30

    We report the synthesis and activation of colloidal carbon nanospheres (CNS) for adsorption of Ag(I) ions from aqueous solutions. CNS (400-500 nm in diameter) was synthesized via simple hydrothermal treatment of glucose solution. The surface of nonporous CNS after being activated by NaOH was enriched with -OH and -COO(-) functional groups. Despite the low surface area (<15m(2)/g), the activated CNS exhibited a high adsorption capacity of 152 mg silver/g. Under batch conditions, all Ag(I) ions can be completely adsorbed in less than 6 min with the initial Ag(I) concentrations lower than 2 ppm. This can be attributed to the minimum mass transfer resistance as Ag(I) ions were all deposited and reduced as Ag(0) nanoparticles on the external surface of CNS. The kinetic data can be well fitted to the pseudo-second-order kinetics model. The adsorbed silver can be easily recovered by dilute acid solutions and the CNS can be reactivated by the same treatment with NaOH solution. The excellent adsorption performance and reusability have also been demonstrated in a continuous mode. The NaOH activated CNS reported here could represent a new type of low-cost and efficient adsorbent nanomaterials for removal of trace Ag(I) ions for drinking water production.

  12. Control of Surface Functional Groups on Pertechntate Sorption on Activated Carbon

    SciTech Connect

    Y. Wang; H. Gao; R. Yeredla; H. Xu; M. Abrecht; G.D. Stasio

    2006-07-05

    {sup 99}Tc is highly soluble and poorly adsorbed by natural materials under oxidizing conditions, thus being of particular concern for radioactive waste disposal. Activated carbon can potentially be used as an adsorbent for removing Tc from aqueous solutions. We have tested six commercial activated carbon materials for their capabilities for sorption of pertechnetate (TcO{sub 4}{sup -}). The tested materials can be grouped into two distinct types: Type I materials have high sorption capabilities with the distribution coefficients (K{sub d}) varying from 9.5 x 10{sup 5} to 3.2 x 10{sup 3} mL/g as the pH changes from 4.5 to 9.5, whereas type II materials have relatively low sorption capabilities with K{sub d} remaining more or less constant (1.1 x 10{sup 3} - 1.8 x 10{sup 3} mL/g) over a similar pH range. The difference in sorption behavior between the two types of materials is attributed to the distribution of surface functional groups. The predominant surface groups are identified to be carboxylic and phenolic groups. The carboxylic group can be further divided into three subgroups A, B, and C in the order of increasing acidity. The high sorption capabilities of type I materials are found to be caused by the presence of a large fraction of carboxylic subgroups A and B, while the low sorption capabilities of type II materials are due to the exclusive presence of phenolic and carboxylic subgroup C. Therefore, the performance of activated carbon for removing TcO{sub 4}{sup -} can be improved by enhancing the formation of carboxylic subgroups A and B during material processing.

  13. Ozone treatment of coal- and coffee grounds-based active carbons: Water vapor adsorption and surface fractal micropores

    SciTech Connect

    Tsunoda, Ryoichi; Ozawa, Takayoshi; Ando, Junichi

    1998-09-15

    Characteristics of the adsorption iostherms of water vapor on active carbons from coal and coffee grounds and those ozonized ones from the surface fractal dimension analysis are discussed. The upswing of the adsorption isotherms in the low relative pressure of coffee grounds-based active carbon, of which isotherms were not scarcely affected on ozonization, was attributed to the adsorption of water molecules on the metallic oxides playing the role of oxygen-surface complexes, which formed the corrugated surfaces on the basal planes of micropore walls with the surface fractal dimension D{sub s} > 2. On the other hand, coal-based active carbon with D{sub s} < 2, which indicated the flat surfaces of micropore walls, showed little effect on the upswing even on ozonization, even though the adsorption amounts of water vapor were increased in the low relative pressure.

  14. Production of activated carbon from coconut shell: optimization using response surface methodology.

    PubMed

    Gratuito, M K B; Panyathanmaporn, T; Chumnanklang, R-A; Sirinuntawittaya, N; Dutta, A

    2008-07-01

    The production of activated carbon from coconut shell treated with phosphoric acid (H3PO4) was optimized using the response surface methodology (RSM). Fifteen combinations of the three variables namely; impregnation ratio (1, 1.5, and 2); activation time (10, 20, and 30 min); and activation temperature (400, 450, and 500 degrees C) were optimized based on the responses evaluated (yield, bulk density, average pore diameter, small pore diameter, and number of pores in a unit area). Pore diameters were directly measured from scanning electron microscope (SEM) images. Individual second-order response surface models were developed and contour plots were generated for the optimization analysis. The optimum range identified for impregnation ratio was from 1.345 to 2, while for the activation time was from 14.9 to 23.9 min. For the activation temperature it was from 394 to 416 degrees C. The optimum points are 1.725, 19.5 min, and 416 degrees C, respectively. The models were able to predict well the values of the responses when the optimum variable parameters were validated as proven by the generally acceptable values of the residual percentages. Direct characterization of the pores using the SEM was found to be a good technique to actually see the pores and get actual measurements. Additionally, RSM has also proven to be a good tool in optimization analysis to get not only optimum production condition points but ranges, which are crucial for the flexibility of the production process, as well.

  15. Role of surface chemistry in modified ACF (activated carbon fiber)-catalyzed peroxymonosulfate oxidation

    NASA Astrophysics Data System (ADS)

    Yang, Shiying; Li, Lei; Xiao, Tuo; Zheng, Di; Zhang, Yitao

    2016-10-01

    A commercial activated carbon fiber (ACF-0) was modified by three different methods: nitration treatment (ACF-N), heat treatment (ACF-H) and heat treatment after nitration (ACF-NH), and the effects of textural and chemical properties on the ability of the metal-free ACF-catalyzed peroxymonosulfate (PMS) oxidation of Reactive Black 5 (RB5), an azo dye being difficultly adsorbed onto ACF, in aqueous solution were investigated in this work. Surface density of functional groups, surface area changes, surface morphology and the chemical state inside ACF samples were characterized by Boehm titration, N2 adsorption, scanning electron microscopy in couple with energy dispersive spectroscopy (SEM-EDS) and X-ray photoelectron spectroscopy (XPS), respectively. XPS spectra deconvolution was applied to figure out the importance of surface nitrogen-containing function groups. We found that π-π, pyridine and amine have promoting effect on the catalytic oxidation while the -NO2 has inhibitory effect on the ACF/PMS systems for RB5 destroy. Sustainability and renewability of the typical ACF-NH for catalytic oxidation of RB5 were also discussed in detail. Information about our conclusions are useful to control and improve the performance of ACF-catalyzed PMS oxidation for organic pollutants in wastewater treatment.

  16. Analysis of the relationship between H{sub 2}S removal capacity and surface properties of unimpregnated activated carbons

    SciTech Connect

    Adib, F.; Bagreev, A.; Bandosz, T.J.

    2000-02-15

    The H{sub 2}S breakthrough capacity was measured on two series of activated carbons of a coconut shell and a bituminous coal origins. To broaden the spectrum of surface features the samples were oxidized using nitric acid or ammonium persulfate under conditions chosen to preserve their pore structures. Then the carbons were characterized using Boehm titration, potentiometric titration, thermal analysis, temperature programmed desorption, sorption of nitrogen, and sorption of water. It was found that the choice of unimpregnated carbon for application as H{sub 2}S adsorbent should be made based on parameters of its acidity such as number of acidic groups, pH of surface, amount of surface groups oxygen, or weight loss associated to decomposition of surface oxygen species. The results obtained from the analyses of six unimpregnated carbon samples suggest that there are certain threshold values of these quantities which, when exceeded, have a dramatic effect on the H{sub 2}S breakthrough capacity.

  17. Microwave permittivity and dielectric relaxation of a high surface area activated carbon

    NASA Astrophysics Data System (ADS)

    Atwater, J. E.; Wheeler, R. R., Jr.

    Carbonaceous materials are amenable to microwave heating to varying degrees. The primary indicator of susceptibility is the complex permittivity (ɛ*), of which, the real component correlates with polarization, and the imaginary term represents dielectric loss. For a given material, the complex permittivity is dependent upon both frequency and temperature. Here we report the complex permittivity of a high surface area coconut shell activated carbon which is commonly used in analytical chemistry and a wide variety of industrial separations. Associated polarization-relaxation phenomena are also characterized. Broadband measurements were made using a high temperature compatible open-ended coaxial dielectric probe at frequencies between 0.2 and 26 GHz, and across the temperature region between 24 °C and 191 °C.

  18. Microbial production, enzyme activity, and carbon turnover in surface sediments of the Hudson River estuary.

    PubMed

    Sinsabaugh, R L; Findlay, S

    1995-09-01

    The detrital food web is a major nexus of energy flow in nearly all aquatic ecosystems. Energy enters this nexus by microbial assimilation of detrital carbon. To link microbiological variables with ecosystem process, it is necessary to understand the regulatory hierarchy that controls the distribution of microbial biomass and activity. Toward that goal, we investigated variability in microbial abundance and activities within the tidal freshwater estuary of the Hudson River. Surface sediments were collected from four contrasting sites: a mid-channel shoal, two types of wetlands, and a tributary confluence. These samples, collected in June to August 1992, were sorted into two to four size fractions, depending on the particle size distribution at each site. Each fraction was analyzed for bacterial biomass (by acridine orange direct counting), bacterial production (by (3)H-thymidine incorporation into DNA), fungal biomass (by ergosterol extraction), fungal production (by biomass accrual), and the potential activities of seven extracellular enzymes involved in the degradation of detrital structural molecules. Decomposition rates for particulate organic carbon (POC) were estimated from a statistical model relating mass loss rates to endocellulase activity. Within samples, bacterial biomass and productivity were negatively correlated with particle size: Standing stocks and rates in the <63-μm class were roughly twofold greater than in the >4-mm class. Conversely, fungal biomass was positively correlated with particle size, with standing stocks in the largest size class more than 1OX greater than in the smallest. Extracellular enzyme activities also differed significantly among size classes, with high carbohydrase activities associated with the largest particles, while oxidative activities predominated in the smallest size classes. Among sites, the mid-channel sediments had the lowest POC standing stock (2% of sediment dry mass) and longest turnover time (approximately 1

  19. Optimization of Orange G dye adsorption by activated carbon of Thespesia populnea pods using response surface methodology.

    PubMed

    Arulkumar, M; Sathishkumar, P; Palvannan, T

    2011-02-15

    Thespesia populnea is a large tree found in the tropical regions and coastal forests of India. Its pods were used as a raw material for the preparation of activated carbon. The prepared activated carbon was used for the adsorptive removal of Orange G dye from aqueous system. The effects of various parameters such as agitation time, initial dye concentration and adsorbent dosage were studied using response surface methodology (RSM). RSM results show that 0.54 g of activated carbon was required for the maximum adsorption of Orange G dye (17.6 mg L(-1)) within a time period of 4.03 h. Adsorption data were modeled using Freundlich and Langmuir adsorption isotherms. The adsorption of Orange G dye by activated carbon obeyed both Fruendlich and Langmuir isotherm. Adsorption kinetic data were tested using pseudo-zero, first, second-order and intraparticle diffusion models. Kinetic studies revealed that the adsorption followed pseudo-second-order reaction with regard to the intraparticle diffusion. FTIR spectral result indicated all the functional group except primary amines (3417 cm(-1)) and CN (1618 cm(-1)) were involved in the adsorption process. XRD data showed that Orange G dye adsorbed activated carbon might not induce the bulk phase changes. SEM results showed that the surface of the activated carbon was turned from dark to light color after dye adsorption.

  20. Modification of granular activated carbon surface by chitosan coating for geosmin removal: sorption performances.

    PubMed

    Vinitnantharat, S; Rattanasirisophon, W; Ishibashi, Y

    2007-01-01

    This study presents the results of the sorption performances for geosmin removal by sorption onto granular activated carbons (GAC) manufactured from different raw materials of coconut shell and bituminous coal. The surface of GAC was modified by chitosan coating. The 90% deacetylated chitosan flakes were used for coating on GAC with the GAC: chitosan ratio of 5:1. The surface of GAC was characterised by scanning electron microscope (SEM) analysis, Fourier transform infrared spectroscopy and measurement of the pH solution of GAC samples. The sorption of geosmin onto the chitosan for both uncoated and coated GACs could be described by the Freundlich adsorption model. Data revealed that the sequence of Freundlich constant (K(F)) was chitosan coated bitominous coal (CB) > uncoated bituminous coal (UB) > chitos approximately equal to an coated coconut shell (CC) approximately equal to uncoated coconut shell (UC). The bituminous coal based GAC with chitosan coating had a maximum capacity of 23.57 microg/g which was approximately two-fold of uncoated bituminous coal based GAC. Two simplified kinetic models, pseudo-first order and pseudo-second order, were tested to investigate the sorption mechanisms. It was found that the intraparticle diffusion was a rate controlling step for the sorption and followed the pseudo-second order equation.

  1. [Adsorption behavior and influence factors of p-nitroaniline on high surface area activated carbons prepared from plant stems].

    PubMed

    Li, Kun-quan; Zheng, Zheng; Luo, Xing-zhang

    2010-08-01

    Low-cost and high surface area microporous activated carbons were prepared from Spartina alternilora and cotton stalk with KOH activation under the conditions of impregnation ratio of 3.0, activation temperature at 800 degrees C and activation time of 1.5 h. The adsorption behavior of p-nitroaniline on the activated carbons was investigated by batch sorption experiments. The influences of solution pH value, adsorbent dose and temperature were investigated. The adsorption isotherm and thermodynamic characteristics were also discussed. The Spartina alterniflora activated carbon (SA-AC) has a high surface area of 2825 m2 x g(-1) and a micropore volume of 1.192 cm3 x g(-1). The BET surface area and micropore volume of the cotton stalk activated carbon (CS-AC) are 2135 m2 x g(-1) and 1.011 cm3 x g(-1), respectively. The sorption experiments show that both the activated carbons have high sorption capacity for p-nitroaniline. The Langmuir maximum sorption amount was found to be 719 mg x g(-1) for SA-AC and 716 mg x g(-1) for CS-AC, respectively. The sorption was found to depend on solution pH, adsorbent dose, and temperature. The optimum pH for the removal of p-nitroaniline was found to be 7.0. The Freundlich model and Redlich-Peterson model can describe the experimental data effectively. The negative changes in free energy (delta G0) and enthalpy (delta H0) indicate that the sorption is a spontaneous and exothermic procedure. The negative values of the adsorption entropy delta S0 indicate that the mobility of p-nitroaniline on the carbon surface becomes more restricted as compared with that of those in solution.

  2. Surface activity of a fluorinated carbohydrate ester in water/carbon dioxide emulsions.

    PubMed

    Favrelle, Audrey; Boyère, Cédric; Tran, Kien My; Alaimo, David; Calvignac, Brice; Paquot, Michel; Boury, Frank; Jérôme, Christine; Debuigne, Antoine

    2013-05-15

    The water/carbon dioxide (W/CO2) interfacial activity and emulsifying capacity of hydrocarbon and fluorinated carbohydrate esters are investigated of the first time and compared to the performance of sodium-bis(2-ethylhexyl)sulfosuccinate (AOT). The reduction of the W/CO2 interfacial tension was measured using a pendant drop tensiometer equipped with a cell view pressurized with CO2 at 80 bar and 45°C. It was found that the interface stabilization improved in the order AOT<6-O-myristoyl mannose<6-O-(2H,2H,3H,3H-perfluoroundecanoyl)-D-mannose. In the latter case, a drastic reduction of the W/CO2 interfacial tension was observed (85% reduction, interfacial tension at the equilibrium=3.6 mN/m), which emphasizes the advantage of using a fluorinated CO2-philic tail and the potential of sugars as hydrophilic head. The formulation of stable W/CO2 emulsions was also achieved using the fluorinated mannose derivative. This study paves the way to the design of a novel class of competitive surface active agents for W/CO2 emulsions.

  3. Energetic changes in the surface of activated carbons and relationship with Ni(II) adsorption from aqueous solution

    NASA Astrophysics Data System (ADS)

    Rodríguez-Estupiñan, Paola; Giraldo, Liliana; Moreno-Piraján, Juan Carlos

    2013-12-01

    This study investigated Ni(II) ion adsorption from aqueous solution on activated carbons obtained by chemically modifying the surface with the oxidizing agents nitric acid and hydrogen peroxide (CAGoxP and CAGoxN, respectively). The activated carbons were characterized by total acidity and basicity, pH at the point of charge zero determination and IR spectroscopy. Textural parameters such as the BET area and pore volumes were evaluated by gas adsorption. The BET area of the materials was between 816 and 876 m2 g-1. Additionally, the immersion enthalpies of the activated carbons in water and benzene were determined. The experimental results on adsorption in solution were adjusted to the Langmuir and Freundlich models, obtaining values for the monolayer capacity between 29.68 and 50.97 mg g-1, which indicates that the adsorption capacity depends largely on solid surface chemistry.

  4. Mechanisms for Olivine Carbonation at the Nili Fossae/Isidis Basin Boundary, Mars: Evidence of Intense Surface Aqueous Activity

    NASA Astrophysics Data System (ADS)

    Mustard, J. F.

    2015-12-01

    One of the most extensive surface deposits of carbonate on Mars is on the slopes of the Isidis Basin rising up to the Nili Fossae region (Ehlmann et al., 2008; Niles et al., 2012; Edwards and Ehlmann 2015). A key factor for the formation of carbonate in this region is the association of carbonate with olivine: this ubiquitous relationship shows the reactants and products are in direct association. There are four clear hypotheses for the geologic environment of formation. 1) Water-rock interaction in the shallow subsurface at slightly elevated temperatures altered olivine to Mg-carbonate perhaps through extended periods of heat and water with burial leading to olivine-serpentine-talc-chlorite alteration pathway (Brown et al., 2010; Viviano et al., 2013). 2) Olivine-rich material, heated by impact or volcanic processes, emplaced on top of a water-bearing phyllosilicate rich unit initiated hydrothermal alteration along the contact. 3) Olivine-rich rocks were weathered to carbonate at surface (cold) temperatures in a manner similar to olivine weathering of meteorites in Antarctica. 4) Carbonate precipitated from shallow ephemeral lakes. These hypotheses are quite different in their predictions of mineral assemblage, water requirements, and habitability. I will show new data and analyses that are providing insights to the question of the mineralogy and assemblages of carbonate-bearing units in the region, diagostic of processes. It is becoming more evident that surface aqueous activity, perhaps involving an extensive cryosphere in the form of Hesperian ice sheets.

  5. Adhesion, cytoskeletal architecture and activation status of primary human macrophages on a diamond-like carbon coated surface.

    PubMed

    Linder, Stefan; Pinkowski, Wolfhard; Aepfelbacher, Martin

    2002-02-01

    Diamond-like carbon is a promising surface coating for biomedicinal implants like coronary stents or hip joints. Before widespread clinical use of this material, its biocompatibility has to be thoroughly assessed. Cells likely to encounter a diamond-like coated implant in the human body are cells of the monocytic lineage. Their interaction with the diamond-like carbon coated surface will probably critically influence the fate of the implant, as monocytes orchestrate inflammatory reactions and also affect osseointegration of implants. We therefore investigated adhesion, cytoarchitecture and activation status of primary human monocytes and their differentiated derivatives, macrophages, on diamond-like coated glass coverslips using immunofluorescence technique. We show that adhesion of primary monocytes to a diamond-like-coated coverslip is slightly, but not significantly, enhanced in comparison to uncoated coverslips, while the actin and microtubule cytoskeletons of mature macrophages show a normal development. The activation status of macrophages, as judged by polarization of the cell body, was not affected by growth on a diamond-like carbon surface. We conclude that diamond-like carbon shows good indications for biocompatibility to blood monocytes in vitro. It is therefore unlikely that contact with a diamond-like carbon coated surface in the human body will elicit inflammatory signals by these cells.

  6. Activated carbon enhanced ozonation of oxalate attributed to HO oxidation in bulk solution and surface oxidation: effect of activated carbon dosage and pH.

    PubMed

    Xing, Linlin; Xie, Yongbing; Minakata, Daisuke; Cao, Hongbin; Xiao, Jiadong; Zhang, Yi; Crittenden, John C

    2014-10-01

    Ozonation of oxalate in aqueous phase was performed with a commercial activated carbon (AC) in this work. The effect of AC dosage and solution pH on the contribution of hydroxyl radicals (HO) in bulk solution and oxidation on the AC surface to the removal of oxalate was studied. We found that the removal of oxalate was reduced by tert-butyl alcohol (tBA) with low dosages of AC, while it was hardly affected by tBA when the AC dosage was greater than 0.3g/L. tBA also inhibited ozone decomposition when the AC dosage was no more than 0.05g/L, but it did not work when the AC dosage was no less than 0.1g/L. These observations indicate that HO in bulk solution and oxidation on the AC surface both contribute to the removal of oxalate. HO oxidation in bulk solution is significant when the dosage of AC is low, whereas surface oxidation is dominant when the dosage of AC is high. The oxalate removal decreased with increasing pH of the solution with an AC dosage of 0.5g/L. The degradation of oxalate occurs mainly through surface oxidation in acid and neutral solution, but through HO oxidation in basic bulk solution. A mechanism involving both HO oxidation in bulk solution and surface oxidation was proposed for AC enhanced ozonation of oxalate.

  7. Importance of surface diffusivities in pesticide adsorption kinetics onto granular versus powdered activated carbon: experimental determination and modeling.

    PubMed

    Baup, S; Wolbert, D; Laplanche, A

    2002-10-01

    Three pesticides (atrazine, bromoxynil and diuron) and two granular activated carbons are involved in equilibrium and kinetic adsorption experiments. Equilibrium is represented by Freundlich isotherm law and kinetic is described by the Homogeneous Surface Diffusion Model, based on external mass transfer and intraparticle surface diffusion. Equilibrium and long-term experiments are conducted to compare Powdered Activated Carbon and Granular Activated Carbon. These first investigations show that crushing GAC into PAC improves the accessibility of the adsorption sites without increasing the number of these sites. In a second part, kinetics experiments are carried out using a Differential Column Batch Reactor. Thanks to this experimental device, the external mass transfer coefficient k(f) is calculated from empirical correlation and the effect of external mass transfer on adsorption is likely to be minimized. In order to obtain the intraparticle surface diffusion coefficient D. for these pesticides, comparisons between experimental kinetic data and simulations are conducted and the best agreement leads to the Ds coefficient. This procedure appears to be an efficient way to acquire surface diffusion coefficients for the adsorption of pesticides onto GAC. Finally it points out the role of surface diffusivity in the adsorption rate. As a matter of fact, even if the amount of the target-compound that could be potentially adsorbed is really important, its surface diffusion coefficient may be small, so that its adsorption may not have enough contact time to be totally achieved.

  8. Observational evidence for an active surface reservoir of solid carbon dioxide on Mars.

    PubMed

    Malin, M C; Caplinger, M A; Davis, S D

    2001-12-07

    High-resolution images of the south polar residual cap of Mars acquired in 1999 and 2001 show changes in the configuration of pits, intervening ridges, and isolated mounds. Escarpments have retreated 1 to 3 meters in 1 martian year, changes that are an order of magnitude larger than can be explained by the sublimation of water ice, but close to what is expected for sublimation of carbon dioxide ice. These observations support a 35-year-old conjecture that Mars has a large surface reservoir of solid carbon dioxide. The erosion implies that this reservoir is not in equilibrium with the present environment and that global climate change is occurring on Mars.

  9. Specific Surface versus Electrochemically Active Area of the Carbon/Polypyrrole Capacitor: Correlation of Ion Dynamics Studied by an Electrochemical Quartz Crystal Microbalance with BET Surface.

    PubMed

    Mosch, Heike L K S; Akintola, Oluseun; Plass, Winfried; Höppener, Stephanie; Schubert, Ulrich S; Ignaszak, Anna

    2016-05-10

    Carbon/polypyrrole (PPy) composites are promising electrode materials for energy storage applications such as lightweight capacitors. Although these materials are composed of relatively inexpensive components, there is a gap of knowledge regarding the correlation between surface, porosity, ion exchange dynamics, and the interplay of the double layer capacitance and pseudocapacitance. In this work we evaluate the specific surface area analyzed by the BET method and the area accessible for ions using electrochemical quartz-crystal microbalance (EQCM) for SWCNT/PPy and carbon black Vulcan XC72-R/PPy composites. The study revealed that the polymer has significant influence on the pore size of the composites. Although the BET surface is low for the polypyrrole, the electrode mass change and thus the electrochemical area are large for the polymer-containing electrodes. This indicates that multiple redox active centers in the charged polymer chain are good ion scavengers. Also, for the composite electrodes, the effective charge storage occurs at the polypyrrole-carbon junctions, which are easy to design/multiply by a proper carbon-to-polymer weight ratio. The specific BET surface and electrochemically accessible surface area are both important parameters in calculation of the electrode capacitance. SWCNTs/PPy showed the highest capacitances normalized to the BET and electrochemical surface as compared to the polymer-carbon black. TEM imaging revealed very homogeneous distribution of the nanosized polymer particles onto the CNTs, which facilitates the synergistic effect of the double layer capacitance (CNTs) and pseudocapacitance (polymer). The trend in the electrode mass change in correlation with the capacitance suggest additional effects such as a solvent co-insertion into the polymer and the contribution of the charge associated with the redox activity of oxygen-containing functional groups on the carbon surface.

  10. Effects of Temperature and Pore Structure on High Surface Area-Activated Carbon Obtained from Peanut Shells.

    PubMed

    Kalpana, D; Lee, Y S

    2016-03-01

    Activated carbon was synthesized from peanut shells by treating with H3PO4 with an intention to enhance the surface area and to find its electrochemical performance in EDLC as electrode material. The powdered peanut shells were pyrolyzed at three different temperatures namely 300 degrees C, 600 degrees C and 800 degrees C respectively. The structural and surface properties of the pyrolyzed carbon materials were studied using N2 adsorption/desorption, Raman, TEM and SEM analysis. There has been remarkable increase in the surface area of the carbon pyrolyzed at 600 degrees C due to the effect of pore generations. The surface area of the 600 degrees C pyrolyzed sample was found to be 1629 m2/g. The electrochemical properties of all the samples were evaluated by cyclic voltammetry, impedance spectroscopy, and galvanostatic charge-discharge tests. The system showed excellent cycleability and a maximum specific capacitance of 291 Fg(-1) was obtained in a 0.1 M H2SO4 electrolyte solution. The effects of the various properties of the activated carbon on the EDLC performance are discussed.

  11. A key parameter on the adsorption of diluted aniline solutions with activated carbons: The surface oxygen content.

    PubMed

    Pardo, Beatrice; Ferrer, Nabí; Sempere, Julià; Gonzalez-Olmos, Rafael

    2016-11-01

    A total of 11 different commercial activated carbons (AC) with well characterized textural properties and oxygen surface content were tested as adsorbents for the removal of aniline as a target water pollutant. The maximum adsorption capacity of aniline for the studied AC was from 138.9 to 257.9 mg g(-1) at 296.15 K and it was observed to be strongly related to the textural properties of the AC, mainly with the BET surface area and the micropore volume. It was not observed any influence of the oxygen surface content of the AC on the maximum adsorption capacity. However, it was found that at low aniline aqueous concentration, the presence of oxygen surface groups plays a dominant role during the adsorption. A high concentration of oxygen surface groups, mainly carboxylic and phenolic groups, decreases the aniline adsorption regardless of the surface area of the AC.

  12. Effects of surface-active organic matter on carbon dioxide nucleation in atmospheric wet aerosols: a molecular dynamics study.

    PubMed

    Daskalakis, Vangelis; Charalambous, Fevronia; Panagiotou, Fostira; Nearchou, Irene

    2014-11-21

    Organic matter (OM) uptake in cloud droplets produces water-soluble secondary organic aerosols (SOA) via aqueous chemistry. These play a significant role in aerosol properties. We report the effects of OM uptake in wet aerosols, in terms of the dissolved-to-gas carbon dioxide nucleation using molecular dynamics (MD) simulations. Carbon dioxide has been implicated in the natural rainwater as well as seawater acidity. Variability of the cloud and raindrop pH is assumed in space and time, as regional emissions, local human activities and geophysical characteristics differ. Rain scavenging of inorganic SOx, NOx and NH3 plays a major role in rain acidity in terms of acid-base activity, however carbon dioxide solubility also remains a key parameter. Based on the MD simulations we propose that the presence of surface-active OM promotes the dissolved-to-gas carbon dioxide nucleation in wet aerosols, even at low temperatures, strongly decreasing carbon dioxide solubility. A discussion is made on the role of OM in controlling the pH of a cloud or raindrop, as a consequence, without involving OM ionization equilibrium. The results are compared with experimental and computational studies in the literature.

  13. Optimum BET surface areas for activated carbon produced from textile sewage sludges and its application as dye removal.

    PubMed

    Kacan, Erdal

    2016-01-15

    The purpose of this experimental study is to determine optimum preparation conditions for activated carbons obtained from textile sewage sludge (TSS) for removal of dyes from aqueous solutions. The textile sewage sludge activated carbon (TSSAC) was prepared by chemical activation with potassium hydroxide using Response Surface Methodology (RSM). The most influential factor on each experimental design responses was identified via ANNOVA analysis. Based on the central composite design (CCD), quadratic model was developed to correlate the preparation variables for one response which is the Brunauer-Emmelt-Teller (BET) surface area. RSM based on a three-variable CCD was used to determine the effect of pyrolyzed temperature (400-700 °C), carbonization time (45-180 min) and KOH: weight of TSS (wt%) impregnation ratio (0.5:1-1.5:1) on BET surface area. According to the results, pyrolyzed temperature and impregnation ratio were found as the significant factors for maximizing the BET surface area. The major effect which influences the BET surface area was found as pyrolyzed temperature. Both carbonization time and impregnation ratio of KOH had no significant effect. The optimum conditions for preparing TSSAC, based on response surface and contour plots, were found as follows: pyrolyzed temperature 700 °C, carbonization time of 45 min and chemical impregnation ratio of 0.5. The maximum and optimum BET surface area of TSSAC were found as 336 m(2)/g and 310.62 m(2)/g, respectively. Synozol Blue reactive (RSB) and Setapers Yellow-Brown (P2RFL) industrial textile dyes adsorption capacities were investigated. As expected the TSSAC which has the biggest BET surface area (336 m(2)/g) adsorbed dye best. The maximum (RSB) and (P2RFL) uptake capacities were found as 8.5383 mg/g and 5.4 mg/g, respectively. The results of this study indicated the applicability of TSSAC for removing industrial dyes from aqueous solution.

  14. Effect of activated carbon surface oxygen- and/or nitrogen-containing groups on adsorption of copper(II) ions from aqueous solution

    SciTech Connect

    Biniak, S.; Pakula, M.; Szymanski, G.S.; Swiatkowski, A.

    1999-08-31

    The adsorption properties of a modified activated carbon with various oxygen-and/or nitrogen-containing surface groups toward copper ions was studied. Previously de-ashed and chemically modified commercial activated carbon D-43/1 (carbo-Tech, Essen, Germany) was used. The chemical properties of the modified carbon surface were estimated by standard neutralization titration with HCl, NaOH, and HaOC{sub 2}{sub 5}. The adsorption of Cu{sup 2+} ions on three modified activated carbons from aqueous CuSO{sub 4} solution of various pH was measured. The carbon samples with adsorbed Cu{sup 2+} ions were analyzed by spectroscopic methods (X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy). In addition, an electrochemical measurement (cyclic voltammetry) was performed using powdered activated carbon electrodes. While the modification procedures employed alter the surface only slightly, they strongly influence the surface chemical structure. Basic groups are predominant in the heat-treated samples; acidic functional groups are predominant in the oxidized sample. Both the copper cation adsorption studies and the spectral and electrochemical measurements show that adsorbed ions interact with the carbon surface in different ways. The number of adsorbed ions depends on the nature and quantity of surface acid-base functionalities and on the pH equilibrium in the aqueous solution. The possible mechanisms of interactions between metal ions and carbon surface functionalities are summarized and discussed.

  15. Preparation of oil palm empty fruit bunch-based activated carbon for removal of 2,4,6-trichlorophenol: optimization using response surface methodology.

    PubMed

    Hameed, B H; Tan, I A W; Ahmad, A L

    2009-05-30

    The effects of three preparation variables: CO(2) activation temperature, CO(2) activation time and KOH:char impregnation ratio (IR) on the 2,4,6-trichlorophenol (2,4,6-TCP) uptake and carbon yield of the activated carbon prepared from oil palm empty fruit bunch (EFB) were investigated. Based on the central composite design, two quadratic models were developed to correlate the three preparation variables to the two responses. The activated carbon preparation conditions were optimized using response surface methodology by maximizing both the 2,4,6-TCP uptake and activated carbon yield within the ranges studied. The optimum conditions for preparing activated carbon from EFB for adsorption of 2,4,6-TCP were found as follows: CO(2) activation temperature of 814 degrees C, CO(2) activation time of 1.9h and IR of 2.8, which resulted in 168.89 mg/g of 2,4,6-TCP uptake and 17.96% of activated carbon yield. The experimental results obtained agreed satisfactorily with the model predictions. The activated carbon prepared under optimum conditions was mesoporous with BET surface area of 1141 m(2)/g, total pore volume of 0.6 cm(3)/g and average pore diameter of 2.5 nm. The surface morphology and functional groups of the activated carbon were respectively determined from the scanning electron microscopy and Fourier transform infrared analysis.

  16. Adsorption of a Textile Dye on Commercial Activated Carbon: A Simple Experiment to Explore the Role of Surface Chemistry and Ionic Strength

    ERIC Educational Resources Information Center

    Martins, Angela; Nunes, Nelson

    2015-01-01

    In this study, an adsorption experiment is proposed using commercial activated carbon as adsorbent and a textile azo dye, Mordant Blue-9, as adsorbate. The surface chemistry of the activated carbon is changed through a simple oxidation treatment and the ionic strength of the dye solution is also modified, simulating distinct conditions of water…

  17. Powder Activated Carbon Pretreatment of a Microfiltration Membrane for the Treatment of Surface Water.

    PubMed

    Song, Yali; Dong, Bingzhi; Gao, Naiyun; Ma, Xiaoyan

    2015-09-10

    This study focused on the effect of powder activated carbon (PAC) adsorption on microfiltration (MF) membrane performance. The results showed that PAC pretreatment offered high organic matter removal rates for both dissolved organic carbon (DOC) and ultraviolet absorbance at 254 nm (UV254) during 10-200 mg/L PAC dosage. The removal efficiencies of organic matter by MF membrane filtration decreased with the increase of organic matter removal rate by PAC adsorption. PAC mainly removed organic matter of about 3 kDa molecular weight (MW). MF membrane maintained more than 5 kDa MW organic matter on the membrane after PAC adsorption. The results of membrane filtration indicated that PAC pretreatment slightly promoted membrane flux, regardless of PAC dosage. It seems that the organic matter fouling membrane was concentrated in more than 3 kDa MW. PAC removed markedly less than 3 kDa MW organic matter and had less effect on more than 3 kDa organic matter. Thus, PAC cannot reduce membrane fouling.

  18. Surface modification of carbon fuels for direct carbon fuel cells

    NASA Astrophysics Data System (ADS)

    Li, Xiang; Zhu, Zhonghua; Chen, Jiuling; De Marco, Roland; Dicks, Andrew; Bradley, John; Lu, Gaoqing

    The direct carbon fuel cell (DCFC) is a promising power-generation device that has much higher efficiency (80%) and less emissions than conventional coal-fired power plants. Two commercial carbons (activated carbon and carbon black) pre-treated with HNO 3, HCl or air plasma are tested in a DCFC. The correlation between the surface properties and electrochemical performance of the carbon fuels is explored. The HNO 3-treated carbon fuels have the highest electrochemical reactivity in the DCFC due to the largest degree of surface oxygen functional groups. The overall effect on changing the electrochemical reactivity of carbon fuels is in the order HNO 3 > air plasma ≈ HCl. Product gas analysis indicates that complete oxidation of carbon to CO 2 can be achieved at 600-700 °C.

  19. In vitro platelet activation, aggregation and platelet-granulocyte complex formation induced by surface modified single-walled carbon nanotubes.

    PubMed

    Fent, János; Bihari, Péter; Vippola, Minnamari; Sarlin, Essi; Lakatos, Susan

    2015-08-01

    Surface modification of single-walled carbon nanotubes (SWCNTs) such as carboxylation, amidation, hydroxylation and pegylation is used to reduce the nanotube toxicity and render them more suitable for biomedical applications than their pristine counterparts. Toxicity can be manifested in platelet activation as it has been shown for SWCNTs. However, the effect of various surface modifications on the platelet activating potential of SWCNTs has not been tested yet. In vitro platelet activation (CD62P) as well as the platelet-granulocyte complex formation (CD15/CD41 double positivity) in human whole blood were measured by flow cytometry in the presence of 0.1mg/ml of pristine or various surface modified SWCNTs. The effect of various SWCNTs was tested by whole blood impedance aggregometry, too. All tested SWCNTs but the hydroxylated ones activate platelets and promote platelet-granulocyte complex formation in vitro. Carboxylated, pegylated and pristine SWCNTs induce whole blood aggregation as well. Although pegylation is preferred from biomedical point of view, among the samples tested by us pegylated SWCNTs induced far the most prominent activation and a well detectable aggregation of platelets in whole blood.

  20. Uniform implantation of CNTs on total activated carbon surfaces: a smart engineering protocol for commercial supercapacitor applications.

    PubMed

    Jiang, Jian; Li, Linpo; Liu, Yani; Liu, Siyuan; Xu, Maowen; Zhu, Jianhui

    2017-04-07

    The main obstacles to building better supercapacitors are still trade-offs between energy and power parameters. To promote commercial supercapacitor behaviors, proper optimization toward electrode configurations/architectures may be a feasible and effective way. We herein propose a smart and reliable electrode engineering protocol, by in situ implantation of carbon nanotubes (CNTs) on total activated carbon (AC) surfaces via a mild chemical vapor deposition process at ∼550 °C, using nickel nitrate hydroxide (NNH) thin films and waste ethanol solvents as the catalyst and carbon sources, respectively. The direct and conformal growth of NNH layers onto carbonaceous scaffold guarantees the later uniform implantation of long and high-quality CNTs on total AC outer surfaces. Such fluffy and entangled CNTs preserve ionic diffusion channels, well connect neighboring ACs and function as superhighways for electrons transfer, endowing electrodes with outstanding capacitive behaviors including large output capacitances of ∼230 F g(-1) in 1 M Na2SO4 neutral solution and ∼502.5 F g(-1) in 6 M KOH using Ni valence state variation, and very negligible capacity decay in long-term cycles. Furthermore, a full symmetric supercapacitor device of CNTs@ACs//CNTs@ACs has been constructed, capable of delivering both high specific energy and power densities (maximum values reaching up to ∼97.2 Wh kg(-1) and ∼10.84 kW kg(-1)), which holds great potential in competing with current mainstream supercapacitors.

  1. Uniform implantation of CNTs on total activated carbon surfaces: a smart engineering protocol for commercial supercapacitor applications

    NASA Astrophysics Data System (ADS)

    Jiang, Jian; Li, Linpo; Liu, Yani; Liu, Siyuan; Xu, Maowen; Zhu, Jianhui

    2017-04-01

    The main obstacles to building better supercapacitors are still trade-offs between energy and power parameters. To promote commercial supercapacitor behaviors, proper optimization toward electrode configurations/architectures may be a feasible and effective way. We herein propose a smart and reliable electrode engineering protocol, by in situ implantation of carbon nanotubes (CNTs) on total activated carbon (AC) surfaces via a mild chemical vapor deposition process at ∼550 °C, using nickel nitrate hydroxide (NNH) thin films and waste ethanol solvents as the catalyst and carbon sources, respectively. The direct and conformal growth of NNH layers onto carbonaceous scaffold guarantees the later uniform implantation of long and high-quality CNTs on total AC outer surfaces. Such fluffy and entangled CNTs preserve ionic diffusion channels, well connect neighboring ACs and function as superhighways for electrons transfer, endowing electrodes with outstanding capacitive behaviors including large output capacitances of ∼230 F g‑1 in 1 M Na2SO4 neutral solution and ∼502.5 F g‑1 in 6 M KOH using Ni valence state variation, and very negligible capacity decay in long-term cycles. Furthermore, a full symmetric supercapacitor device of CNTs@ACs//CNTs@ACs has been constructed, capable of delivering both high specific energy and power densities (maximum values reaching up to ∼97.2 Wh kg‑1 and ∼10.84 kW kg‑1), which holds great potential in competing with current mainstream supercapacitors.

  2. New Carbon Activation Process for Increased Surface Accessibility in Electrochemical Capacitors

    SciTech Connect

    Doughty, Daniel H.; Eisenmann, Erhard T.

    1999-03-16

    A process for making carbon film or powder suitable for double capacitor electrodes having a capacitance of up to about 300 F/cm{sup 3} is disclosed. This is accomplished by treating in aqueous nitric acid for a period of about 5 to 15 minutes thin carbon films obtained by carbonizing carbon-containing polymeric material having a high degree of molecular directionality, such as polyimide film, then heating the treated carbon film in a non-oxidizing atmosphere at a non-graphitizing temperature of at least 350 C for about 20 minutes, and repeating alternately the nitric acid step and the heating step from 7 to 10 times. Capacitors made with this carbon may find uses ranging from electronic devices to electric vehicle applications.

  3. Carbon spectrum utilization by an indigenous strain of Pseudomonas aeruginosa NCIM 5514: Production, characterization and surface active properties of biosurfactant.

    PubMed

    Varjani, Sunita J; Upasani, Vivek N

    2016-12-01

    The present research work was undertaken with a mandate to study carbon spectrum utilization and structural characterization of biosurfactant produced by indigenous Pseudomonas aeruginosa NCIM 5514, which showed unique properties to utilize a large number of carbon sources effectively for production of biosurfactant, although glucose was the best carbon substrate. In Bushnell-Hass medium supplemented with glucose (1%, w/v), 3.178±0.071g/l biosurfactant was produced by this isolate in 96h. The biosurfactant produced showed surface tension and emulsification activity values from 29.14±0.05 to 62.29±0.13mN/m and 88.50±1.96 to 15.40±0.91%, respectively. Toluene showed highest emulsification activity followed by kerosene. However, kerosene exhibited emulsion stability for 30days. Biosurfactant was characterized as a mixture of di-rhamnolipid (Rha-Rha-C10-C14:1) and mono-rhamnolipid (Rha-C8-C10) by FTIR, ESI-MS and LC-MS techniques. High biosurfactant yield opens up doors for the isolate to find utility in various industries.

  4. Development of surface functionalized activated carbon fiber for control of NO and particulate matter.

    PubMed

    Rathore, Rajveer Singh; Srivastava, Dhananjay Kumar; Agarwal, Avinash Kumar; Verma, Nishith

    2010-01-15

    This study investigates the development and potential application of activated carbon fibers (ACF) functionalized with ammonia for control of NO and particulate matter (PM) in diesel engine exhaust. A tubular reactor packed with ACF was used to experimentally study the oxidation of NO at room temperature. Tests were conducted at ACF functionalized with three aqueous ammonia concentrations (3, 5, 10 M), three basic reagents (ammonia, pyridine, amine) and three NO concentrations (100, 300, 500 ppm). After offline investigation, the ACF-packed tubular reactor was installed downstream of the engine's exhaust to ascertain the PM capturing efficiency of ACF. The experimental conditions for PM removal included three weights of ACF (2, 3.5, 4.5 g), three engine loads (0, 25, 50 Nm) and three temperatures (150, 300, 450 degrees C). The maximum 70% conversion for NO was obtained at NO concentration of 300 ppm for ACF functionalized with 5M ammonia, whereas maximum 90% reduction in PM was observed at engine load of 25 Nm and 450 degrees C. The study shows significant potential for the ACF based filters in capturing both homogeneous and heterogeneous pollutants emitted from automobiles. Our previously developed transport model incorporating the mechanism for the oxidation of NO was also used to explain the experimental data.

  5. Effect of Polarity of Activated Carbon Surface, Solvent and Adsorbate on Adsorption of Aromatic Compounds from Liquid Phase.

    PubMed

    Goto, Tatsuru; Amano, Yoshimasa; Machida, Motoi; Imazeki, Fumio

    2015-01-01

    In this study, introduction of acidic functional groups onto a carbon surface and their removal were carried out through two oxidation methods and outgassing to investigate the adsorption mechanism of aromatic compounds which have different polarity (benzene and nitrobenzene). Adsorption experiments for these aromatics in aqueous solution and n-hexane solution were conducted in order to obtain the adsorption isotherms for commercial activated carbon (BAC) as a starting material, its two types of oxidized BAC samples (OXs), and their outgassed samples at 900 °C (OGs). Adsorption and desorption kinetics of nitrobenzene for the BAC, OXs and OGs in aqueous solution were also examined. The results showed that the adsorption of benzene molecules was significantly hindered by abundant acidic functional groups in aqueous solution, whereas the adsorbed amount of nitrobenzene on OXs gradually increased as the solution concentration increased, indicating that nitrobenzene can adsorb favourably on a hydrophilic surface due to its high dipole moment, in contrast to benzene. In n-hexane solution, it was difficult for benzene to adsorb on any sample owing to the high affinity between benzene and n-hexane solvent. On the other hand, adsorbed amounts of nitrobenzene on OXs were larger than those of OGs in n-hexane solution, implying that nitrobenzene can adsorb two adsorption sites, graphene layers and surface acidic functional groups. The observed adsorption and desorption rate constants of nitrobenzene on the OXs were lower than those on the BAC due to disturbance of diffusion by the acidic functional groups.

  6. Effects of pretreatment on the surface chemistry and pore size properties of nitrogen functionalized and alkylated granular activated carbon

    NASA Astrophysics Data System (ADS)

    Chen, Jiajun; Zhai, Yunbo; Chen, Hongmei; Li, Caiting; Zeng, Guangming; Pang, Daoxiong; Lu, Pei

    2012-12-01

    In this paper, granular activated carbon (GAC) from coconut shell was pretreated by HNO3, H2O2 and urea-formaldehyde resin, respectively. Then the obtained materials were functionalized in the same way for nitrogen group, and then alkylated. Effects of pretreatment on the surface chemistry and pore size of modified GACs were studied. Surface area and micropore volume of modified GAC which pretreated by HNO3 were 723.88 m2/g and 0.229 cm3/g, respectively, while virgin GAC were 742.34 m2/g and 0.276 cm3/g. Surface area and micropore volume decrease of the modified GACs which pretreated by the others two methods were more drastically. The types of groups presented were analyzed by electrophoresis, Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). Nsbnd CH3 group and Cdbnd N group were detected on the surfaces of these three kinds of modified GACs. Results of XPS showed that the nitrogen functions of modified GAC which pretreated by H2O2 was 4.07%, it was more than that of the others two pretreatment methods. However, the modified GAC which pretreated by urea-formaldehyde resin was fixed more pyridine structure, which structure percentage was 45.88%, in addition, there were more basic groups or charge on the surface than the others.

  7. High surface area carbon and process for its production

    DOEpatents

    Romanos, Jimmy; Burress, Jacob; Pfeifer, Peter; Rash, Tyler; Shah, Parag; Suppes, Galen

    2016-12-13

    Activated carbon materials and methods of producing and using activated carbon materials are provided. In particular, biomass-derived activated carbon materials and processes of producing the activated carbon materials with prespecified surface areas and pore size distributions are provided. Activated carbon materials with preselected high specific surface areas, porosities, sub-nm (<1 nm) pore volumes, and supra-nm (1-5 nm) pore volumes may be achieved by controlling the degree of carbon consumption and metallic potassium intercalation into the carbon lattice during the activation process.

  8. Impact of natural organic matter on monochloramine reduction by granular activated carbon: the role of porosity and electrostatic surface properties

    SciTech Connect

    Julian L. Fairey; Gerald E. Speitel Jr.; Lynn E. Katz

    2006-07-01

    Steady-state monochloramine reduction in fixed-bed reactors (FBRs) was quantified on five types of granular activated carbon (GAC) using two background waters - one natural source water (LAW) containing 2.5-3.5 mg/L organic carbon and one synthetic organic-free water (NW). GACs used were coal-based Filtrasorb 400, Filtrasorb 600, Centaur and Medical Grade, and wood-based AquaGuard. While more monochloramine was reduced at steady-state using NW compared to LAW for each GAC and empty-bed contact time studied, the differences in removal varied considerably among the GACs tested. Physical characterization of the GACs suggested that the degree of interference caused by natural organic matter (NOM) increased with increasing GAC surface area contained within pores greater than 2 nm in width. Acid/base and electrostatic properties of the GACs were not found to be significant in terms of NOM uptake, which indicated that size exclusion effects of the GAC pores overwhelmed the impact of the GAC surface chemistry. Therefore, selection of GAC to limit the impact of NOM on monochloramine reduction in FBRs should be based on pore size distribution alone, with the impact of NOM decreasing with decreasing mesoporosity and macroporosity. 23 refs., 4 figs., 3 tabs.

  9. Theoretical study of γ-hexachlorocyclohexane and β-hexachlorocyclohexane isomers interaction with surface groups of activated carbon model.

    PubMed

    Enriquez-Victorero, Carlos; Hernández-Valdés, Daniel; Montero-Alejo, Ana Lilian; Durimel, Axelle; Gaspard, Sarra; Jáuregui-Haza, Ulises

    2014-06-01

    Activated carbon (AC) is employed in drinking water purification without almost any knowledge about the adsorption mechanism of persistent organic pollutants (POPs) onto it. Hexachlorocyclohexane (HCH) is an organochlorinated contaminant present in water and soils of banana crops production zones of the Caribbean. The most relevant isomers of HCH are γ-HCH and β-HCH, both with great environmental persistence. A theoretical study of the influence of AC surface groups (SGs) on HCH adsorption is done in order to help to understand the process and may lead to improve the AC selection process. A simplified AC model consisting of naphthalene with a functional group was used to assess the influence of SGs over the adsorption process. The Multiple Minima Hypersurface (MMH) methodology was employed to study γ-HCH and β-HCH interactions with different AC SGs (hydroxyl and carboxyl) under different hydration and pH conditions. The results obtained showed that association of HCH with SGs preferentially occurs between the axial protons of HCH and SG's oxygen atom, and the most favorable interactions occurring with charged SGs. An increase in carboxylic SGs content is proposed to enhance HCH adsorption onto AC under neutral pH conditions. Finally, this work presents an inexpensive computer aided methodology for preselecting activated carbon SGs content for the removal of a given compound.

  10. Landfill leachate treatment using powdered activated carbon augmented sequencing batch reactor (SBR) process: optimization by response surface methodology.

    PubMed

    Aziz, Shuokr Qarani; Aziz, Hamidi Abdul; Yusoff, Mohd Suffian; Bashir, Mohammed J K

    2011-05-15

    In this study, landfill leachate was treated by using the sequencing batch reactor (SBR) process. Two types of the SBR, namely non-powdered activated carbon and powdered activated carbon (PAC-SBR) were used. The influence of aeration rate and contact time on SBR and PAC-SBR performances was investigated. Removal efficiencies of chemical oxygen demand (COD), colour, ammoniacal nitrogen (NH(3)-N), total dissolved salts (TDS), and sludge volume index (SVI) were monitored throughout the experiments. Response surface methodology (RSM) was applied for experimental design, analysis and optimization. Based on the results, the PAC-SBR displayed superior performance in term of removal efficiencies when compared to SBR. At the optimum conditions of aeration rate of 1L/min and contact time of 5.5h the PAC-SBR achieved 64.1%, 71.2%, 81.4%, and 1.33% removal of COD, colour, NH(3)-N, and TDS, respectively. The SVI value of PAC-SBR was 122.2 mL/g at optimum conditions.

  11. Optimization of process variables by response surface methodology for malachite green dye removal using lime peel activated carbon

    NASA Astrophysics Data System (ADS)

    Ahmad, Mohd Azmier; Afandi, Nur Syahidah; Bello, Olugbenga Solomon

    2015-04-01

    This study investigates the adsorptive removal of malachite green (MG) dye from aqueous solutions using chemically modified lime-peel-based activated carbon (LPAC). The adsorbent prepared was characterized using FTIR, SEM, Proximate analysis and BET techniques, respectively. Central composite design (CCD) in response surface methodology (RSM) was used to optimize the adsorption process. The effects of three variables: activation temperature, activation time and chemical impregnation ratio (IR) using KOH and their effects on percentage of dye removal and LPAC yield were investigated. Based on CCD design, quadratic models and two factor interactions (2FI) were developed correlating the adsorption variables to the two responses. Analysis of variance (ANOVA) was used to judge the adequacy of the model. The optimum conditions of MG dye removal using LPAC are: activation temperature (796 °C), activation time (1.0 h) and impregnation ratio (2.6), respectively. The percentage of MG dye removal obtained was 94.68 % resulting in 17.88 % LPAC yield. The percentage of error between predicted and experimental results for the removal of MG dye is 0.4 %. Model prediction was in good agreement with experimental results and LPAC was found to be effective in removing MG dye from aqueous solution.

  12. Influence of the pore structure and surface chemical properties of activated carbon on the adsorption of mercury from aqueous solutions.

    PubMed

    Lu, Xincheng; Jiang, Jianchun; Sun, Kang; Wang, Jinbiao; Zhang, Yanping

    2014-01-15

    Reactivation and chemical modification were used to obtain modified activated carbons with different pore structure and surface chemical properties. The samples were characterized by nitrogen absorption-desorption, Fourier transform infrared spectroscopy and the Bothem method. Using mercury chloride as the target pollutant, the Hg(2+) adsorption ability of samples was investigated. The results show that the Hg(2+) adsorption capacity of samples increased significantly with increases in micropores and acidic functional groups and that the adsorption process was exothermic. Different models and thermodynamic parameters were evaluated to establish the mechanisms. It was concluded that the adsorption occurred through a monolayer mechanism by a two-speed process involving both rapid adsorption and slow adsorption. The adsorption rate was determined by chemical reaction.

  13. Surface carbon transformations at a site of active continental serpentinization: the Tablelands, Newfoundland, Canada

    NASA Astrophysics Data System (ADS)

    Rietze, A.; Szponar, N.; Lang, S. Q.; Kohl, L.; Morrill, P. L.

    2013-12-01

    The Tablelands in Newfoundland, Canada contain terrestrial peridotite-hosted groundwater springs associated with serpentinization. These springs act as windows into subsurface systems and provide insight into their biogeochemistry. However, at sites where ultra-basic water pools and mixes with overland flow the reactions in the pools must be considered when trying to source organic compounds. We will present data from a pool (WHC2) located in the Tablelands to determine the biogeochemical carbon transformations at this mixing site. The ultra-basic, reducing groundwater springs had higher concentrations of alkanes (C1-C4) and organic acids (acetate and formate) than the overland flow, suggesting that these organics originated from the groundwater source. A two component mixing model was developed to predict what the concentrations of alkanes and organic acids would be in the WHC2 pool based on physical mixing of groundwater and overland flow. Acetate and C2-C4 alkane concentrations were fairly well predicted by the mixing model, suggesting little consumption or production of this organic acid and these alkanes in the pool. However, methane concentrations were under predicted by the model at two sampling points in the pool, suggesting production of methane at these sites. At the same two sampling locations formate concentrations were over predicted by the model, suggesting that formate was being consumed in the pool. The water at these sampling times was highly reducing; therefore oxidation of formate was not likely responsible for the consumption of formate. Organic acid fermentation using formate is one possible sink for formate and source for methane. However, the genomic data from the site has shown little evidence for microbial methanogenesis (1). Geochemical measurements of the carbon in the pool can help elucidate the most dominant source of methane. On a Bernard plot (C1/C2+ vs. δ13CCH4 (‰)) the alkanes measured at the springs plot in the thermogenic

  14. Equilibrium and column adsorption studies of 2,4-dinitroanisole (DNAN) on surface modified granular activated carbons.

    PubMed

    Boddu, V M; Abburi, K; Fredricksen, A J; Maloney, S W; Damavarapu, R

    2009-02-01

    2,4-Dinitroanisole (DNAN) is used as a component extensively in the development of insensitive munitions. This may result in release of DNAN into the environment. Here, the results are reported of a study on the removal characteristics of DNAN through adsorption on granular activated carbon (GAC), chitosan coated granular activated carbon (CGAC), acid treated granular activated carbon (AGAC) and alkali treated granular activated carbon (BGAC) under equilibrium and column flow conditions. The effect of pH, contact time, concentration of DNAN, and presence of electrolytes on the uptake of DNAN by the adsorbents was investigated. The equilibrium data were fitted to different types of adsorption isotherms. The data were further analysed on the basis of Lagergren first-order, pseudo second-order and intraparticle diffusion kinetic models. Breakthrough curves were obtained based on column flow results. All the adsorbents were capable of removing about 99% of DNAN from aqueous media, except CGAC which adsorbed about 87% of DNAN.

  15. 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.

  16. 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.

  17. Synergy between surface adsorption and photocatalysis during degradation of humic acid on TiO2/activated carbon composites.

    PubMed

    Xue, Gang; Liu, Huanhuan; Chen, Quanyuan; Hills, Colin; Tyrer, Mark; Innocent, Francis

    2011-02-15

    A photocatalyst comprising nano-sized TiO(2) particles on granular activated carbon (GAC) was prepared by a sol-dipping-gel process. The TiO(2)/GAC composite was characterized by scanning electron microscopy (SEM), X-ray diffractiometry (XRD) and nitrogen sorptometry, and its photocatalytic activity was studied through the degradation of humic acid (HA) in a quartz glass reactor. The factors influencing photocatalysis were investigated and the GAC was found to be an ideal substrate for nano-sized TiO(2) immobilization. A 99.5% removal efficiency for HA from solution was achieved at an initial concentration of 15 mg/L in a period of 3h. It was found that degradation of HA on the TiO(2)/GAC composite was facilitated by the synergistic relationship between surface adsorption characteristics and photocatalytic potential. The fitting of experimental results with the Langmuir-Hinshelwood (L-H) model showed that the reaction rate constant and the adsorption constant values were 0.1124 mg/(L min) and 0.3402 L/mg. The latter is 1.7 times of the calculated value by fitting the adsorption equilibrium data into the Langmuir equation.

  18. Theoretical study of chlordecone and surface groups interaction in an activated carbon model under acidic and neutral conditions.

    PubMed

    Gamboa-Carballo, Juan José; Melchor-Rodríguez, Kenia; Hernández-Valdés, Daniel; Enriquez-Victorero, Carlos; Montero-Alejo, Ana Lilian; Gaspard, Sarra; Jáuregui-Haza, Ulises Javier

    2016-04-01

    Activated carbons (ACs) are widely used in the purification of drinking water without almost any knowledge about the adsorption mechanisms of the persistent organic pollutants. Chlordecone (CLD, Kepone) is an organochlorinated synthetic compound that has been used mainly as agricultural insecticide. CLD has been identified and listed as a persistent organic pollutant by the Stockholm Convention. The selection of the best suited AC for this type of contaminants is mainly an empirical and costly process. A theoretical study of the influence of AC surface groups (SGs) on CLD adsorption is done in order to help understanding the process. This may provide a first selection criteria for the preparation of AC with suitable surface properties. A model of AC consisting of a seven membered ring graphene sheet (coronene) with a functional group on the edge was used to evaluate the influence of the SGs over the adsorption. Multiple Minima Hypersurface methodology (MMH) coupled with PM7 semiempirical Hamiltonian was employed in order to study the interactions of the chlordecone with SGs (hydroxyl and carboxyl) at acidic and neutral pH and different hydration conditions. Selected structures were re-optimized using CAM-B3LYP to achieve a well-defined electron density to characterize the interactions by the Quantum Theory of Atoms in Molecules approach. The deprotonated form of surface carboxyl and hydroxyl groups of AC models show the strongest interactions, suggesting a chemical adsorption. An increase in carboxylic SGs content is proposed to enhance CLD adsorption onto AC at neutral pH conditions.

  19. 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.

  20. Toward the use of surface modified activated carbon in speciation: selective preconcentration of selenite and selenate in environmental waters.

    PubMed

    Tsoi, Yeuk-Ki; Leung, Kelvin Sze-Yin

    2011-04-22

    This paper describes a novel application of tetrabutylammonium hydroxide-modified activated carbon (AC-TBAH) to the speciation of ultra-trace Se(IV) and Se(VI) using LC-ICP-DRC-MS. The anion exchange functionality was immobilized onto the AC surface enables selective preconcentration of inorganic Se anions in a wide range of working pHs. Simultaneous retention and elution of both analytes, followed by subsequent analysis with LC-ICP-DRC-MS, allows to accomplish speciation analysis in natural samples without complicated redox pre-treatment. The laboratory-made column of immobilized AC (0.4 g of sorbent packed in a 6 mL syringe barrel) has achieved analyte enrichment factors of 76 and 93, respectively, for Se(IV) and Se(VI), thus proving its superior preconcentration efficiency and selectivity over common AC. The considerable enhancement in sensitivity achieved by using the preconcentration column has improved the method's detection limits to 1.9-2.2 ng L(-1), which is a 100-fold improvement compared with direct injection. The analyte recoveries from heavily polluted river matrix were between 95.3 and 107.7% with less than 5.0% RSD. The robustness of the preconcentration and speciation method was validated by analysis of natural waters collected from rivers and reservoirs in Hong Kong. The modified AC material is hence presented as a low-cost yet robust substitute for conventional anion exchange resins for routine applications.

  1. Optimization of Cu/activated carbon catalyst in low temperature selective catalytic reduction of NO process using response surface methodology.

    PubMed

    Amanpour, Javad; Salari, Dariush; Niaei, Aligholi; Mousavi, Seyed Mahdi; Panahi, Parvaneh Nakhostin

    2013-01-01

    Preparation of Cu/Activated Carbon (Cu/AC) catalyst was optimized for low temperature selective catalytic reduction of NO by using response surface methodology. A central composite design (CCD) was used to investigate the effects of three independent variables, namely pre-oxidization degree (HNO3%), Cu loading (wt.%) and calcination temperature on NO conversion efficiency. The CCD was consisted of 20 different preparation conditions of Cu/AC catalysts. The prepared catalysts were characterized by XRD and SEM techniques. Predicting NO conversion was carried out using a second order model obtained from designed experiments and statistical software Minitab 14. Regression and Pareto graphic analysis showed that all of the chosen parameters and some interactions were effective on the NO conversion. The optimal values were pre-oxidization in 10.2% HNO3, 6.1 wt.% Cu loading and 480°C for calcination temperature. Under the optimum condition, NO conversion (94.3%) was in a good agreement with predicted value (96.12%).

  2. Influence of surface oxygenated groups on the formation of active Cu species and the catalytic activity of Cu/AC catalyst for the synthesis of dimethyl carbonate

    NASA Astrophysics Data System (ADS)

    Zhang, Guoqiang; Li, Zhong; Zheng, Huayan; Hao, Zhiqiang; Wang, Xia; Wang, Jiajun

    2016-12-01

    Activated carbon (AC) supported Cu catalysts are employed to study the influence of surface oxygenated groups on the formation of active Cu species and the catalytic activity of Cu/AC catalyst for oxidative carbonylation of methanol to dimethyl carbonate (DMC). The AC supports are thermal treated under different temperatures in order to adjust the levels of surface oxygenated groups. The AC supports are characterized by BET, TPD-MS and XRD, and the Cu/AC catalysts are characterized by BET, XRD, TEM, XPS, AAS, CH3OH-TPD and N2O chemisorption. The results show that as the treatment temperature is below 800 °C, the BET surface area of the corresponding AC supports are nearly unchanged and close to that of the original AC (1529.6 m2/g). But as the thermal treatment temperature is elevated from 1000 to 1600 °C, the BET surface area of AC supports gradually decreases from 1407.6 to 972.2 m2/g. After loading of Cu, the BET surface area of copper catalysts is in the range of 834.4 to 1545.3 m2/g, which is slightly less than that of the respective supports. When AC is thermal treated at 400 and 600 °C, the unstable carboxylic acid and anhydrides groups are selectively removed, which has weakened the mobility and agglomeration of Cu species during the calcination process, and thus improve the Cu species dispersion over AC support. But as the treatment temperature is elevated from 600 °C to 1200 °C, the Cu species dispersion begins to decline suggesting further removal of stable surface oxygenated groups is unfavorable for Cu species dispersion. Moreover, higher thermal treatment temperature (above 1200 °C) promotes the graphitization degree of AC and leds to the decrease of Cu loading on AC support. Meanwhile, the removal of surface oxygenated groups by thermal treatment is conducive to the formation of more π-sites, and thus promote the reduction of Cu2+ to Cu+ and Cu0 as active centers. The specific surface area of (Cu+ + Cu0) is improved by thermal treatment of AC

  3. 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.

  4. 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.

  5. Effect of pH and surface chemistry on the mechanism of H{sub 2}S removal by activated carbons

    SciTech Connect

    Adib, F.; Bagreev, A.; Bandosz, T.J.

    1999-08-15

    The performances of three wood-based activated carbons as adsorbents of hydrogen sulfide were evaluated by dynamic breakthrough testing. The subsequent products of H{sub 2}S oxidation on the carbon surfaces were analyzed. The adsorbents were studied using sorption of nitrogen, thermal analysis, Boehm titration, FTIR, ion chromatography, and temperature programmed desorption. Based on the results, the effects of surface chemistry and structural features on the yield of water soluble products and on the regenerability of the exhausted carbons were evaluated. The results showed that the breakthrough capacity and the yield on regeneration depend on the average pH of the carbon surface related to the pH in local pore environment. When the surface is very acidic, the dissociation of H{sub 2}S is suppressed resulting in a very small concentration of hydrogen sulfide ions and thus in the formation of highly dispersed sulfur. Such conditions are favorable for oxidation of sulfur to S{sup 4+} and S{sup 6+}. When the surface is less acidic the degree of dissociation is higher and the creation of polymeric elemental sulfur species resistant to further oxidation is more favorable. A small increase in pH (half a unit) in the acidic range results in a 15-fold increase in hydrogen sulfide breakthrough capacity accompanied by only a one third decrease in the yield of sulfur oxides.

  6. Mesoporous magnetic activated carbon: Effect of preparation route on texture and surface properties and on effect for Reactive Black 5 adsorption.

    NASA Astrophysics Data System (ADS)

    Giannakoudakis, Dimitrios; Saroyan, Hayarpi; Lazaridis, Nikolaos; Deliyanni, Eleni

    2016-04-01

    Mesoporous magnetic activated carbon: Effect of preparation route on texture and surface properties and on effect for Reactive Black 5 adsorption. Dimitrios Giannakoudakis1, Hayarpi Saroyan2, Nikolaos Lazaridis2, Eleni Deliyanni2 1 City College of New York, Chemistry Department, 160 Convent Avenue, New York, United States 2 Laboratory of General and oInorganic Chemical Technology, Department of Chemistry, Aristotle University of Thessaloniki, GR-541 24 Thessaloniki, Greece In this study, the effect of preparation route of a mesoporous magnetic activated carbon on Reactive Black 5 (RB5) adsorption was investigated. The synthesis of the magnetic activated carbon was achieved both with (i) impregnation method (Bmi), and (ii) co-precipitation with two precipitation agents: NaOH (Bm) and NH4OH (Bma). After synthesis, the full characterization with various techniques (SEM, FTIR, XRD, DTA, DTG, VSM) was achieved in order to testify the effect of the preparation route on its textural and surface properties. It was shown that after the precipitation method the prepared carbon presented a collapsed texture and small magnetic properties. Effects of initial solution pH, effect of temperature, adsorption isotherms and kinetics were investigated in order to conclude about the aforementioned effect of the preparation method on dye adsorption performance of the magnetic carbons. The adsorption evaluation of the magnetic activated carbon presented higher adsorption capacity of Bmi carbon (350 mg/g) and lower of Bm (150 mg/g). Equilibrium experiments are also performed studying the effect of contact time (pseudo-first and -second order equations) and temperature (isotherms at 25, 45 and 65 °C fitted to Langmuir and Freundlich model). A full thermodynamic evaluation was carried out, calculating the parameters of enthalpy, free energy and entropy (ΔHο, ΔGο and ΔSο). The characterization with various techniques revealed the possible interactions/forces of dye-composite system.

  7. Bacterial community in the biofilm of granular activated carbon (GAC) PreBiofilter in bench-scale pilot plants for surface water pretreatment.

    PubMed

    Wu, Tiehang; Fu, George Yuzhu; Sabula, Michael; Brown, Tommy

    2014-12-01

    Biofilters of granular activated carbon (GAC) are responsible for the removal of organic matters in drinking water treatments. PreBiofilters, which operate as the first unit in a surface water treatment train, are a cost-effective pretreatment for conventional surface water treatment and provide more consistent downstream water quality. This study investigated bacterial communities from the samples of raw surface water, biofilm on the PreBiofilter, and filtrates for surface water pretreatment. A bench-scale pilot plant of PreBiofilter was constructed to pretreat surface water from the Canoochee River, GA, USA. PreBiofilter exhibited a significant reduction of total organic carbon and dissolved organic carbon. The evenness and Shannon diversity of bacterial operational taxonomic units (OTUs) were significantly higher on the biofilm of PreBiofilter than in raw water and filtrates. Similar bacteria communities were observed in the raw water and filtrates using relative abundance of bacterial OTUs. However, the bacterial communities in the filtrates became relatively similar to those in the biofilm using presence/absence of bacterial OTUs. GAC biofilm or raw water and filtrates greatly contributed to the abundance of bacteria; whereas, bacteria sheared from colonized biofilm and entered filtrates. Evenly distributed, diverse and unique bacteria in the biofilm played an important role to remove organic matters from surface water for conventional surface water pretreatment.

  8. Surface Seal for Carbon Parts

    NASA Technical Reports Server (NTRS)

    Shuford, D. M.; Spruiell, J. P.

    1982-01-01

    Surface pores in parts made of graphite or reinforced-carbon/ carbon materials are sealed by a silicon carbide-based coating. Coating inhibits subsurface oxidation and lengthens part life. Starting material for coating is graphite felt, which is converted to silicon carbide felt by processing it according to a prescribed time/temperature schedule. Converted felt is pulverized in a ball mill and resulting powder is mixed with an equal weight of black silicon carbide powder. Powder mixture is combined with an equal weight of adhesive to form a paste.

  9. SERS activity of Ag decorated nanodiamond and nano-β-SiC, diamond-like-carbon and thermally annealed diamond thin film surfaces.

    PubMed

    Kuntumalla, Mohan Kumar; Srikanth, Vadali Venkata Satya Siva; Ravulapalli, Satyavathi; Gangadharini, Upender; Ojha, Harish; Desai, Narayana Rao; Bansal, Chandrahas

    2015-09-07

    In the recent past surface enhanced Raman scattering (SERS) based bio-sensing has gained prominence owing to the simplicity and efficiency of the SERS technique. Dedicated and continuous research efforts have been made to develop SERS substrates that are not only stable, durable and reproducible but also facilitate real-time bio-sensing. In this context diamond, β-SiC and diamond-like-carbon (DLC) and other related thin films have been promoted as excellent candidates for bio-technological applications including real time bio-sensing. In this work, SERS activities of nanodiamond, nano-β-SiC, DLC, thermally annealed diamond thin film surfaces were examined. DLC and thermally annealed diamond thin films were found to show SERS activity without any metal nanostructures on their surfaces. The observed SERS activities of the considered surfaces are explained in terms of the electromagnetic enhancement mechanism and charge transfer resonance process.

  10. Nanostructure of Poly(Acrylic Acid) Adsorption Layer on the Surface of Activated Carbon Obtained from Residue After Supercritical Extraction of Hops

    NASA Astrophysics Data System (ADS)

    Wiśniewska, M.; Nosal-Wiercińska, A.; Ostolska, I.; Sternik, D.; Nowicki, P.; Pietrzak, R.; Bazan-Wozniak, A.; Goncharuk, O.

    2017-01-01

    The nanostructure of poly(acrylic acid) (PAA) adsorption layer on the surface of mesoporous-activated carbon HPA obtained by physical activation of residue after supercritical extraction of hops was characterized. This characterization has been done based on the analysis of determination of adsorbed polymer amount, surface charge density, and zeta potential of solid particles (without and in the PAA presence). The SEM, thermogravimetric, FTIR, and MS techniques have allowed one to examine the solid surface morphology and specify different kinds of HPA surface groups. The effects of solution pH, as well as polymer molecular weight and concentration, were studied. The obtained results indicated that the highest adsorption on the activated carbon surface was exhibited by PAA with lower molecular weight (i.e., 2000 Da) at pH 3. Under such conditions, polymeric adsorption layer is composed of nanosized PAA coils (slightly negatively charged) which are densely packed on the positive surface of HPA. Additionally, the adsorption of polymeric macromolecules into solid pores is possible.

  11. Nanostructure of Poly(Acrylic Acid) Adsorption Layer on the Surface of Activated Carbon Obtained from Residue After Supercritical Extraction of Hops.

    PubMed

    Wiśniewska, M; Nosal-Wiercińska, A; Ostolska, I; Sternik, D; Nowicki, P; Pietrzak, R; Bazan-Wozniak, A; Goncharuk, O

    2017-12-01

    The nanostructure of poly(acrylic acid) (PAA) adsorption layer on the surface of mesoporous-activated carbon HPA obtained by physical activation of residue after supercritical extraction of hops was characterized. This characterization has been done based on the analysis of determination of adsorbed polymer amount, surface charge density, and zeta potential of solid particles (without and in the PAA presence). The SEM, thermogravimetric, FTIR, and MS techniques have allowed one to examine the solid surface morphology and specify different kinds of HPA surface groups. The effects of solution pH, as well as polymer molecular weight and concentration, were studied. The obtained results indicated that the highest adsorption on the activated carbon surface was exhibited by PAA with lower molecular weight (i.e., 2000 Da) at pH 3. Under such conditions, polymeric adsorption layer is composed of nanosized PAA coils (slightly negatively charged) which are densely packed on the positive surface of HPA. Additionally, the adsorption of polymeric macromolecules into solid pores is possible.

  12. Electrochemical capacitors utilizing low surface area carbon fiber

    SciTech Connect

    Lipka, S.M.

    1997-12-01

    The performance of electrochemical capacitors containing different commercial carbon fibers is reviewed. High specific capacitances (ca. 300 F/g) are obtained with low surface area carbon fiber (<1 m2/g) using a proprietary activation process. Capacitance is primarily achieved through pseudocapacitance resulting from surface functional groups. The performance of these devices is dependent on the type of carbon fiber, its carbon content, aspect ratio and microstructure. These devices can achieve high cycle life (ca. 100k) without significant loss in capacitance.

  13. Carbon Nanomaterials: Surface Structure and Morphology

    NASA Astrophysics Data System (ADS)

    Mansurov, Z. A.; Shabanova, T. A.; Mofa, N. N.; Glagolev, V. A.

    2014-09-01

    We propose a classification of individual nanoparticles on the basis of the form of the surface and the internal architectural packing for investigations carried out with the help of transmission electron microscopy. The investigated samples contain individual nanoparticles of seven kinds in different ratios: rounded, tubular, fibrous, fi lm, "veil," "active" particles and "particles with regular geometric contours." The classification was made on the basis of an analysis of the results of investigations of the surfaces and internal architectural packing of carbon particles obtained in different physiochemical processes (carbonization, carburizing, arc discharge, mechanochemical treatment, plasma chemistry, and in carbon-containing fl ames). For the source materials, we used waste of farming products and widely distributed mineral raw materials.

  14. Effects of Microporosity and Surface Chemistry on Separation Performances of N-Containing Pitch-Based Activated Carbons for CO2/N2 Binary Mixture

    PubMed Central

    Lee, Min-Sang; Park, Mira; Kim, Hak Yong; Park, Soo-Jin

    2016-01-01

    In this study, N-containing pitch-based activated carbons (NPCs) were prepared using petroleum pitch with a low softening point and melamine with a high nitrogen content. The major advantage of the preparation method is that it enables variations in chemical structures and textural properties by steam activation at high temperatures. The adequate micropore structures, appropriate chemical modifications, and high adsorption enthalpies of NPCs are favorable for CO2 adsorption onto carbon surfaces. Furthermore, the structure generates a considerable gas/N-containing carbon interfacial area, and provides selective access to CO2 molecules over N2 molecules by offering an increased number of active sites on the carbon surfaces. The highest CO2/N2 selectivity, i.e., 47.5, and CO2 adsorption capacity for a CO2/N2 (0.15:0.85) binary gas mixture, i.e., 5.30 wt%, were attained at 298 K. The NPCs also gave reversible and durable CO2-capturing performances. All the results suggest that NPCs are promising CO2 sorbents, which can meet the challenges of current CO2 capture and separation techniques. PMID:26987683

  15. Effects of Microporosity and Surface Chemistry on Separation Performances of N-Containing Pitch-Based Activated Carbons for CO2/N2 Binary Mixture

    NASA Astrophysics Data System (ADS)

    Lee, Min-Sang; Park, Mira; Kim, Hak Yong; Park, Soo-Jin

    2016-03-01

    In this study, N-containing pitch-based activated carbons (NPCs) were prepared using petroleum pitch with a low softening point and melamine with a high nitrogen content. The major advantage of the preparation method is that it enables variations in chemical structures and textural properties by steam activation at high temperatures. The adequate micropore structures, appropriate chemical modifications, and high adsorption enthalpies of NPCs are favorable for CO2 adsorption onto carbon surfaces. Furthermore, the structure generates a considerable gas/N-containing carbon interfacial area, and provides selective access to CO2 molecules over N2 molecules by offering an increased number of active sites on the carbon surfaces. The highest CO2/N2 selectivity, i.e., 47.5, and CO2 adsorption capacity for a CO2/N2 (0.15:0.85) binary gas mixture, i.e., 5.30 wt%, were attained at 298 K. The NPCs also gave reversible and durable CO2-capturing performances. All the results suggest that NPCs are promising CO2 sorbents, which can meet the challenges of current CO2 capture and separation techniques.

  16. Photoconductivity of activated carbon fibers

    SciTech Connect

    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. 54 refs., 11 figs., 3 tabs.

  17. 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.

  18. In-duct removal of mercury from coal-fired power plant flue gas by activated carbon: assessment of entrained flow versus wall surface contributions

    SciTech Connect

    Scala, F.; Chirone, R.; Lancia, A.

    2008-12-15

    In-duct mercury capture efficiency by activated carbon from coal-combustion flue gas was investigated. To this end, elemental mercury capture experiments were conducted at 100 C in a purposely designed 65-mm ID labscale pyrex apparatus operated as an entrained flow reactor. Gas residence times were varied between 0.7 and 2.0 s. Commercial-powdered activated carbon was continuously injected in the reactor and both mercury concentration and carbon elutriation rate were followed at the outlet. Transient mercury concentration profiles at the outlet showed that steady-state conditions were reached in a time interval of 15-20 min, much longer than the gas residence time in the reactor. Results indicate that the influence of the walls is non-negligible in determining the residence time of fine carbon particles in the adsorption zone, because of surface deposition and/or the establishment of a fluid-dynamic boundary layer near the walls. Total mercury capture efficiencies of 20-50% were obtained with carbon injection rates in the range 0.07-0.25 g/min. However, only a fraction of this capture was attributable to free-flowing carbon particles, a significant contribution coming from activated carbon staying near the reactor walls. Entrained bed experiments at lab-scale conditions are probably not properly representative of full-scale conditions, where the influence of wall interactions is lower. Moreover, previously reported entrained flow lab-scale mercury capture data should be reconsidered by taking into account the influence of particle-wall interactions.

  19. Effect of surface modification of an engineered activated carbon on the sorption of 2,4-dichlorophenoxy acetic acid and benazolin from water.

    PubMed

    Chingombe, P; Saha, B; Wakeman, R J

    2006-05-15

    The performance of a conventional (F400) and a surface modified activated carbon (F400AN) has been investigated for the sorption of benazolin and 2,4-dichlorophenoxy acetic acid (2,4-D) from water. It was observed that the modified carbon, F400AN, which was obtained by annealing the conventional sample had a higher BET surface area (960 m2 g(-1) compared to 790 m2 g(-1)) and it had a higher proportion of micropores. This was attributed to the loss of oxygen containing functional groups during the thermal treatment. Zeta potential and pH titration measurements also showed that acidic functionality had been lost on the F400AN sample. The adsorption data were analysed and were fitted well using the Langmuir isotherm. The modified carbon marginally out-performed the conventional activated carbon for sorption of these two herbicides. Thermodynamic parameters (DeltaG0, DeltaH0, and DeltaS0) were determined and their values indicated that the sorption process was spontaneous and endothermic for both herbicides. A pseudo-second-order kinetic model was employed for analysing the kinetic data. It was concluded that the herbicide sorption process was controlled by a film diffusion mechanism.

  20. Surface modification of porous suspended ceramsite used for water treatment by activated carbon/Fe3O4 magnetic composites.

    PubMed

    Lu, Mang; Xia, Guang-Hua; Zhao, Xiao-Dong

    2013-01-01

    In this study, porous suspended ceramsite with a specific density close to that of water was prepared by high-temperature calcination using fly ash, feldspar, calcite, fired talc and kaolin as the raw materials. The ceramsite was modified by activated carbon/Fe3O4 magnetic composites. The optimum modification conditions determined by methylene blue adsorption experiment were: KOH/glucose ratio of 1.5:1, carbonization temperature of 400 degrees C, activation temperature of 850 degrees C, activation time of 1 h, and Fe3O4/KOH+glucose ratio of 1:10. The results demonstrated that the adsorption capacity of the modified ceramsite for methylene blue was significantly higher than that of the unmodified ones. The presence of the composites did not lead to significant decrease in the mechanical properties of the modified ceramsite. Moreover, the modified ceramsite showed good resistance towards acid and alkali. The modified ceramsite can be used as biocarrier and adsorbent for a wide range of contaminants in water and can subsequently be removed from the medium by a simple magnetic procedure.

  1. High concentration powdered activated carbon-membrane bioreactor (PAC-MBR) for slightly polluted surface water treatment at low temperature.

    PubMed

    Ma, Cong; Yu, Shuili; Shi, Wenxin; Tian, Wende; Heijman, S G J; Rietveld, L C

    2012-06-01

    In this study, different concentrations of PAC combined with MBR were carried out to treat slightly polluted surface water (SPSW) at low temperature (10°C). Effects of PAC on the efficiencies of operation, treatment, and the performance of the process were investigated. It was found that the effluent quality, performance efficiency, resistance of shock load were all enhanced and chemical irreversible membrane fouling was reduced with increasing dosage of PAC in MBR. Only when the concentration of PAC which acted as biological carriers was high enough (i.g., 50 g/L), nitrification without initial inoculation in the filtration tank could start within 19 days and be completed within 35 days at 10°C. Fifty grams per liter PAC was the optimal dosage in MBR for stable and extended operation. Under this condition, mean removal efficiencies of ammonia nitrogen (NH(3)-N), dissolved organic carbon (DOC) and UV(254) were 93%, 75%, and 85%, respectively.

  2. The electrode as organolithium reagent: catalyst-free covalent attachment of electrochemically active species to an azide-terminated glassy carbon electrode surface.

    PubMed

    Das, Atanu K; Engelhard, Mark H; Liu, Fei; Bullock, R Morris; Roberts, John A S

    2013-12-02

    The reaction of a lithium acetylide-ethylenediamine complex with azide-terminated glassy carbon surfaces affords 1,2,3-triazolyllithium surface groups that are active toward covalent C-C coupling reactions, including salt metathesis with an aliphatic halide and nucleophilic addition at an aldehyde. Surface ferrocenyl groups were introduced by reaction with (6-iodohexyl)ferrocene; the voltammetry of electrode samples shows narrow, symmetric peaks indicating uniform attachment. X-ray photoelectron and reflectance infrared spectroscopic data provide further support for the surface-attached products. Formation of the 1,2,3-triazolyllithium linkage requires neither a catalyst nor a strained alkyne. Coverages obtained by this route are similar to those obtained by the more common Cu(I)-catalyzed alkyne-azide coupling (CuAAC) of ethynylferrocene with surface azides. Preconditioning of the glassy carbon disk electrodes at ambient temperature under nitrogen affords coverages comparable to those reported with preconditioning at 1000 °C under hydrogen/nitrogen.

  3. 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.

  4. 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.

  5. 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

  6. Response surface modeling and optimization of chromium(VI) removal from aqueous solution using Tamarind wood activated carbon in batch process.

    PubMed

    Sahu, J N; Acharya, Jyotikusum; Meikap, B C

    2009-12-30

    The present paper discusses response surface methodology (RSM) as an efficient approach for predictive model building and optimization of chromium adsorption on developed activated carbon. In this work the application of RSM is presented for optimizing the removal of Cr(VI) ions from aqua solutions using activated carbon as adsorbent. All experiments were performed according to statistical designs in order to develop the predictive regression models used for optimization. The optimization of adsorption of chromium on activated carbon was carried out to ensure a high adsorption efficiency at low adsorbent dose and high initial concentration of Cr(VI). While the goal of adsorption of chromium optimization was to improve adsorption conditions in batch process, i.e., to minimize the adsorbent dose and to increase the initial concentration of Cr(VI). In the adsorption experiments a laboratory developed Tamarind wood activated carbon made of chemical activation (zinc chloride) was used. A 2(4) full factorial central composite design experimental design was employed. Analysis of variance (ANOVA) showed a high coefficient of determination value (R(2)=0.928) and satisfactory prediction second-order regression model was derived. Maximum chromium removal efficiency was predicted and experimentally validated. The optimum adsorbent dose, temperature, initial concentration of Cr(VI) and initial pH of the Cr(VI) solution were found to be 4.3g/l, 32 degrees C, 20.15 mg/l and 5.41 respectively. Under optimal value of process parameters, high removal (>89%) was obtained for Cr(VI).

  7. Application of optimized large surface area date stone (Phoenix dactylifera ) activated carbon for rhodamin B removal from aqueous solution: Box-Behnken design approach.

    PubMed

    Danish, Mohammed; Khanday, Waheed Ahmad; Hashim, Rokiah; Sulaiman, Nurul Syuhada Binti; Akhtar, Mohammad Nishat; Nizami, Maniruddin

    2017-05-01

    Box-Behnken model of response surface methodology was used to study the effect of adsorption process parameters for Rhodamine B (RhB) removal from aqueous solution through optimized large surface area date stone activated carbon. The set experiments with three input parameters such as time (10-600min), adsorbent dosage (0.5-10g/L) and temperature (25-50°C) were considered for statistical significance. The adequate relation was found between the input variables and response (removal percentage of RhB) and Fisher values (F- values) along with P-values suggesting the significance of various term coefficients. At an optimum adsorbent dose of 0.53g/L, time 593min and temperature 46.20°C, the adsorption capacity of 210mg/g was attained with maximum desirability. The negative values of Gibb(')s free energy (ΔG) predicted spontaneity and feasibility of adsorption; whereas, positive Enthalpy change (ΔH) confirmed endothermic adsorption of RhB onto optimized large surface area date stone activated carbons (OLSADS-AC). The adsorption data were found to be the best fit on the Langmuir model supporting monolayer type of adsorption of RhB with maximum monolayer layer adsorption capacity of 196.08mg/g.

  8. Textured carbon surfaces on copper by sputtering

    NASA Technical Reports Server (NTRS)

    Curren, A. N. (Inventor); Jensen, K. A. (Inventor); Roman, R. F. (Inventor)

    1986-01-01

    A very thin layer of highly textured carbon is applied to a copper surface by a triode sputtering process. A carbon target and a copper substrate are simultaneously exposed to an argon plasma in a vacuum chamber. The resulting carbon surface is characterized by a dense, random array of needle like spires or peaks which extend perpendicularly from the copper surface. The coated copper is especially useful for electrode plates in multistage depressed collectors.

  9. Surface free energy ( γsd) of active carbons determined by inverse gas chromatography: influences of the origin of precursors, the burn off level and the chemical modification

    NASA Astrophysics Data System (ADS)

    Cossarutto, L.; Vagner, C.; Finqueneisel, G.; Weber, J. V.; Zimny, T.

    2001-06-01

    The dispersive component of the surface free energies ( γsd) of commercial active carbons (AC) from various origins were determined by inverse gas chromatography at infinite dilution (IGC-ID). This method discriminates clearly the AC produced from wood (and activated/carbonised with phosphoric acid) and those from coconut-shell (carbonised and steam activated at 850°C). The values for the last AC (from coconut) are twice higher than the values for AC of wood origin. The structure and shape of the pores have to be considered to explain these values. It seems that for AC, IGC-ID globally characterises the most energetic micropores. This can be observed, in this work, by two ways: (i) washing of commercial AC (chemically activated) allows to liberate a part of the micropores blocked by soluble phosphate and consequently increases the γsd value; (ii) modifying coconuts AC by chemical treatment (formamide) results in a strong decrease of both microporosity and γsd value. On the contrary, thermal activation of the modified AC increases at the same time the microporosity and the surface free energy. Finally, we demonstrate that the IGC method is also an useful tool to monitor in situ the evolutions of the surface properties of carbonaceous materials.

  10. 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.

  11. 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.

  12. Deposition of Magnetite Nanoparticles in Activated Carbons and Preparation of Magnetic Activated Carbons

    NASA Astrophysics Data System (ADS)

    Kahani, S. A.; Hamadanian, M.; Vandadi, O.

    2007-08-01

    Magnetic activated carbons (MACs) for gold recovery from alkaline cyanide solutions have been developed by mixing a magnetic precursor with a carbon source, and treating the mixture under controlled conditions. As would be expected, these activated carbons have high specific surface areas due to their microporous structure. In addition, the small particle size of the MACs produced allows rapid adsorption of gold in solution, and the magnetic character of these MACs enables recovery from suspension by magnetic separation.

  13. Chemical activation of carbon mesophase pitches.

    PubMed

    Mora, E; Blanco, C; Pajares, J A; Santamaría, R; Menéndez, R

    2006-06-01

    This paper studies the chemical activation of mesophase pitches of different origins in order to obtain activated carbons suitable for use as electrodes in supercapacitors. The effect that the activating agent (NaOH, LiOH, and KOH), the alkaline hydroxide/pitch ratio, and the activation temperature had on the characteristics of the resultant activated carbons was studied. LiOH was found to be a noneffective activating agent, while activation with NaOH and KOH yielded activated carbons with high apparent surface areas and pore volumes. The increase of the KOH/pitch ratio caused an increase of the chemical attack on the carbon, producing higher burnoffs and development of porosity. Extremely high apparent surface areas were obtained when the petroleum pitch was activated with 5:1 KOH/carbon ratio. The increase of the activation temperature caused an increase of the burnoff, although the differences were not as significant as those derived from the use of different proportions of activating agent.

  14. Carbon speciation and surface tension of fog

    USGS Publications Warehouse

    Capel, P.D.; Gunde, R.; Zurcher, F.; Giger, W.

    1990-01-01

    The speciation of carbon (dissolved/particulate, organic/inorganic) and surface tension of a number of radiation fogs from the urban area of Zurich, Switzerland, were measured. The carbon species were dominated by "dissolved" organic carbon (DOC; i.e., the fraction that passes through a filter), which was typically present at levels of 40-200 mg/L. Less than 10% of the DOC was identified as specific individual organic compounds. Particulate organic carbon (POC) accounted for 26-41% of the mass of the particles, but usually less than 10% of the total organic carbon mass. Inorganic carbon species were relatively minor. The surface tensions of all the measured samples were less than pure water and were correlated with their DOC concentrations. The combination of high DOC and POC and low surface tension suggests a mechanism for the concentration of hydrophobic organic contaminants in the fog droplet, which have been observed by numerous investigators. ?? 1990 American Chemical Society.

  15. Preparation of mesoporous activated carbon from palm-date pits: optimization study on removal of bentazon, carbofuran, and 2,4-D using response surface methodology.

    PubMed

    Salman, J M; Abid, F M

    2013-01-01

    Palm-date pits were used to prepare activated carbon by physiochemical activation method, which consisted of potassium hydroxide (KOH) treatment and carbon dioxide (CO(2)) gasification. The effects of variable parameters, activation temperature, activation time and chemical impregnation ratios (KOH: char by weight) on the preparation of activated carbon and for removal of pesticides: bentazon, carbofuran and 2,4-dichlorophenoxyacetic acid (2,4-D) were investigated. Based on the central composite design (CCD), two factor interaction (2FI) and quadratic models were respectively employed to correlate the effect of variable parameters on the preparation of activated carbon used for removal of pesticides with carbon yield. From the analysis of variance (ANOVA), the most influential factor on each experimental design response was identified. The optimum conditions for preparing activated carbon from palm-date pits were found to be: activation temperature of 850 °C, activation time of 3 h and chemical impregnation ratio of 3.75, which resulted in an activated carbon yield of 19.5% and bentazon, carbofuran, and 2,4-D removal of 84, 83, and 93%, respectively.

  16. 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.

  17. 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

  18. An X-ray photoelectron spectroscopy study of surface changes on brominated and sulfur-treated activated carbon sorbents during mercury capture: performance of pellet versus fiber sorbents.

    PubMed

    Saha, Arindom; Abram, David N; Kuhl, Kendra P; Paradis, Jennifer; Crawford, Jenni L; Sasmaz, Erdem; Chang, Ramsay; Jaramillo, Thomas F; Wilcox, Jennifer

    2013-12-03

    This work explores surface changes and the Hg capture performance of brominated activated carbon (AC) pellets, sulfur-treated AC pellets, and sulfur-treated AC fibers upon exposure to simulated Powder River Basin-fired flue gas. Hg breakthrough curves yielded specific Hg capture amounts by means of the breakthrough shapes and times for the three samples. The brominated AC pellets showed a sharp breakthrough after 170-180 h and a capacity of 585 μg of Hg/g, the sulfur-treated AC pellets exhibited a gradual breakthrough after 80-90 h and a capacity of 661 μg of Hg/g, and the sulfur-treated AC fibers showed no breakthrough even after 1400 h, exhibiting a capacity of >9700 μg of Hg/g. X-ray photoelectron spectroscopy was used to analyze sorbent surfaces before and after testing to show important changes in quantification and oxidation states of surface Br, N, and S after exposure to the simulated flue gas. For the brominated and sulfur-treated AC pellet samples, the amount of surface-bound Br and reduced sulfur groups decreased upon Hg capture testing, while the level of weaker Hg-binding surface S(VI) and N species (perhaps as NH4(+)) increased significantly. A high initial concentration of strong Hg-binding reduced sulfur groups on the surface of the sulfur-treated AC fiber is likely responsible for this sorbent's minimal accumulation of S(VI) species during exposure to the simulated flue gas and is linked to its superior Hg capture performance compared to that of the brominated and sulfur-treated AC pellet samples.

  19. Preparation and Electrocatalytic Activity of Gold Nanoparticles Immobilized on the Surface of 4-Mercaptobenzoyl-Functionalized Multiwalled Carbon Nanotubes

    DTIC Science & Technology

    2010-12-20

    Friedel - Crafts acylation reaction. 24-26 The reaction medium is both mild and nondestructive and plays two important roles for the effective dispersion...the functionalization of multiwalled carbon nano- tubes (MWCNTs) with 4-mercaptobenzoic acid by a “direct” Friedel - Crafts acylation reaction to afford...MWCNTs were prepared using a “direct” Friedel - Crafts acylation reaction in a PPA/P2O5 medium. The reaction between the MWCNTs and MBAc typi- cally

  20. 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.

  1. The Electrode as Organolithium Reagent: Catalyst-Free Covalent Attachment of Electrochemically Active Species to an Azide-Terminated Glassy Carbon Electrode Surface

    SciTech Connect

    Das, Atanu K.; Engelhard, Mark H.; Liu, Fei; Bullock, R. Morris; Roberts, John A.

    2013-12-02

    Glassy carbon electrodes have been activated for modification with azide groups and subsequent coupling with ferrocenyl reagents by a catalyst-free route using lithium acetylide-ethylenediamine complex, and also by the more common Cu(I)-catalyzed alkyne-azide coupling (CuAAC) route, both affording high surface coverages. Electrodes were preconditioned at ambient temperature under nitrogen, and ferrocenyl surface coverages obtained by CuAAC were comparable to those reported with preconditioning at 1000 °C under hydrogen/nitrogen. The reaction of lithium acetylide-ethylenediamine with the azide-terminated electrode affords a 1,2,3-triazolyllithium-terminated surface that is active toward covalent C-C coupling reactions including displacement at an aliphatic halide and nucleophilic addition at an aldehyde. For example, surface ferrocenyl groups were introduced by reaction with (6-iodohexyl)ferrocene; the voltammetry shows narrow, symmetric peaks indicating uniform attachment. Coverages are competitive with those obtained by the CuAAC route. X-ray photoelectron spectroscopic data, presented for each synthetic step, are consistent with the proposed reactions. This research was supported as part of the Center for Molecular Electrocatalysis, an Energy Frontier Research Center funded by the US Department of Energy, Office of Science, Office of Basic Energy Sciences. Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy. A portion of the research was performed using EMSL, a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory.

  2. Preparation of nitrogen-doped cotton stalk microporous activated carbon fiber electrodes with different surface area from hexamethylenetetramine-modified cotton stalk for electrochemical degradation of methylene blue

    NASA Astrophysics Data System (ADS)

    Li, Kunquan; Rong, Zhang; Li, Ye; Li, Cheng; Zheng, Zheng

    Cotton-stalk activated carbon fibers (CSCFs) with controllable micropore area and nitrogen content were prepared as an efficient electrode from hexamethylenetetramine-modified cotton stalk by steam/ammonia activation. The influence of microporous area, nitrogen content, voltage and initial concentration on the electrical degradation efficiency of methylene blue (MB) was evaluated by using CSCFs as anode. Results showed that the CSCF electrodes exhibited excellent MB electrochemical degradation ability including decolorization and COD removal. Increasing micropore surface area and nitrogen content of CSCF anode leaded to a corresponding increase in MB removal. The prepared CSCF-800-15-N, which has highest N content but lowest microporous area, attained the best degradation effect with 97% MB decolorization ratio for 5 mg/L MB at 12 V in 4 h, implying the doped nitrogen played a prominent role in improving the electrochemical degradation ability. The electrical degradation reaction was well described by first-order kinetics model. Overall, the aforesaid findings suggested that the nitrogen-doped CSCFs were potential electrode materials, and their electrical degradation abilities could be effectively enhanced by controlling the nitrogen content and micropore surface area.

  3. 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.

  4. Surface photovoltage spectroscopy of carbon nitride powder

    SciTech Connect

    Dittrich, Th.; Fiechter, S.; Thomas, A.

    2011-08-22

    Powder of carbon nitride has been investigated by surface photovoltage spectroscopy at temperatures between 30 deg. C and 150 deg. C. Photo-generated holes were preferentially separated towards the external surface. Electronic states below the optical band gap from which charge separation may be possible have not been observed. The band gap of the investigated carbon nitride decreased from 2.93 to 2.80 eV with increasing temperature from 30 deg. C to 150 deg. C. The material exhibits a higher optical transition at E = 3.6 eV. Results are discussed from the point of view of photo-catalytic water splitting with carbon nitride.

  5. ROLE OF SURFACE FUNCTIONAL GROUPS IN THE CAPTURE OF ELEMENTAL MERCURY AND MERCURIC CHLORIDE BY ACTIVATED CARBONS

    EPA Science Inventory

    The paper discusses using a laboratory-scale, fixed bed apparatus to study the role of surface functional groups (SFGs) in the capture of mercuric chloride (HgC12) and elemental mercury (Hgo) in nitrogen (N2) prior to flue gas atmosphere studies. The study focused on two activat...

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

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

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

  7. 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

  8. Influence of activated carbon porosity and surface oxygen functionalities' presence on adsorption of acetonitrile as a simple polar volatile organic compound.

    PubMed

    Furmaniak, Sylwester

    2015-01-01

    Based on series of porous carbon models, systematic Monte Carlo studies on the adsorption of acetonitrile (as a simple representative of polar volatile organic compounds) were performed. The influence of porosity and chemical composition of the carbon surface on CH3CN adsorption was studied and it was shown that both the factors influenced the adsorption mechanism. A decrease in the pore size and the introduction of oxygen surface groups led to a rise in adsorption energy and to an increase in the filling of accessible volume in the low-pressure part of the isotherm. However, from a practical point of view, it is easier to increase the adsorption by introducing polar groups on the carbon surface than by modifying the porosity.

  9. 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.

  10. CARBON SEQUESTRATION SURFACE MINE LANDS

    SciTech Connect

    Donald H. Graves; Christopher Barton; Richard Sweigard; Richard Warner

    2003-07-24

    Over 160 acres of tree seedlings were planted during the last quarter. This quarter marked the beginning of the installation of new instrumentation and the inspection and calibration of previously installed recording devices. Sampling systems were initiated to quantify initial seedling success as well as height measurements. Nursery seedlings have been inoculated to produce mycorrhizal treated stock for 2004 spring plantings to determine the effects on carbon sequestration. All planting areas in western Kentucky have been sampled with the recording cone penetrometer and the nuclear density gauge to measure soil density.

  11. Making Activated Carbon for Storing Gas

    NASA Technical Reports Server (NTRS)

    Wojtowicz, Marek A.; Serio, Michael A.; Suuberg, Eric M.

    2005-01-01

    Solid disks of microporous activated carbon, produced by a method that enables optimization of pore structure, have been investigated as means of storing gas (especially hydrogen for use as a fuel) at relatively low pressure through adsorption on pore surfaces. For hydrogen and other gases of practical interest, a narrow distribution of pore sizes <2 nm is preferable. The present method is a variant of a previously patented method of cyclic chemisorption and desorption in which a piece of carbon is alternately (1) heated to the lower of two elevated temperatures in air or other oxidizing gas, causing the formation of stable carbon/oxygen surface complexes; then (2) heated to the higher of the two elevated temperatures in flowing helium or other inert gas, causing the desorption of the surface complexes in the form of carbon monoxide. In the present method, pore structure is optimized partly by heating to a temperature of 1,100 C during carbonization. Another aspect of the method exploits the finding that for each gas-storage pressure, gas-storage capacity can be maximized by burning off a specific proportion (typically between 10 and 20 weight percent) of the carbon during the cyclic chemisorption/desorption process.

  12. Method for in-situ cleaning of carbon contaminated surfaces

    DOEpatents

    Klebanoff, Leonard E.; Grunow, Philip; Graham, Jr., Samuel

    2006-12-12

    Activated gaseous species generated adjacent a carbon contaminated surface affords in-situ cleaning. A device for removing carbon contamination from a surface of the substrate includes (a) a housing defining a vacuum chamber in which the substrate is located; (b) a source of gaseous species; and (c) a source of electrons that are emitted to activate the gaseous species into activated gaseous species. The source of electrons preferably includes (i) a filament made of a material that generates thermionic electron emissions; (ii) a source of energy that is connected to the filament; and (iii) an electrode to which the emitted electrons are attracted. The device is particularly suited for photolithography systems with optic surfaces, e.g., mirrors, that are otherwise inaccessible unless the system is dismantled. A method of removing carbon contaminants from a substrate surface that is housed within a vacuum chamber is also disclosed. The method employs activated gaseous species that react with the carbon contaminants to form carbon containing gaseous byproducts.

  13. Stability and effects of carbon-induced surface reconstructions in cobalt Fischer-Tropsch synthesis

    NASA Astrophysics Data System (ADS)

    Ciobîcă, I. M.; van Helden, P.; van Santen, R. A.

    2016-11-01

    This computational study of carbon induced reconstruction of Co surfaces demonstrates that surface reconstruction is stable in the presence of a hydrogen at low coverage. These reconstructions can create new sites that allow for low activation energy CO dissociation. Carbon induced surface reconstruction of the edge of the FCC-Co(221) step surface will result in highly reactive step-edge sites. Such sites also provide a low activation energy for carbon to diffuse into the subsurface layer of cobalt.

  14. Superhydrophobic activated carbon-coated sponges for separation and absorption.

    PubMed

    Sun, Hanxue; Li, An; Zhu, Zhaoqi; Liang, Weidong; Zhao, Xinhong; La, Peiqing; Deng, Weiqiao

    2013-06-01

    Highly porous activated carbon with a large surface area and pore volume was synthesized by KOH activation using commercially available activated carbon as a precursor. By modification with polydimethylsiloxane (PDMS), highly porous activated carbon showed superhydrophobicity with a water contact angle of 163.6°. The changes in wettability of PDMS- treated highly porous activated carbon were attributed to the deposition of a low-surface-energy silicon coating onto activated carbon (confirmed by X-ray photoelectron spectroscopy), which had microporous characteristics (confirmed by XRD, SEM, and TEM analyses). Using an easy dip-coating method, superhydrophobic activated carbon-coated sponges were also fabricated; those exhibited excellent absorption selectivity for the removal of a wide range of organics and oils from water, and also recyclability, thus showing great potential as efficient absorbents for the large-scale removal of organic contaminants or oil spills from water.

  15. 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

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

    PubMed

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

    2013-01-01

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

  17. Experimental design based response surface methodology optimization of ultrasonic assisted adsorption of safaranin O by tin sulfide nanoparticle loaded on activated carbon.

    PubMed

    Roosta, M; Ghaedi, M; Daneshfar, A; Sahraei, R

    2014-03-25

    In this research, the adsorption rate of safranine O (SO) onto tin sulfide nanoparticle loaded on activated carbon (SnS-NPAC) was accelerated by the ultrasound. SnS-NP-AC was characterized by different techniques such as SEM, XRD and UV-Vis measurements. The present results confirm that the ultrasound assisted adsorption method has remarkable ability to improve the adsorption efficiency. The influence of parameters such as the sonication time, adsorbent dosage, pH and initial SO concentration was examined and evaluated by central composite design (CCD) combined with response surface methodology (RSM) and desirability function (DF). Conducting adsorption experiments at optimal conditions set as 4 min of sonication time, 0.024 g of adsorbent, pH 7 and 18 mg L(-1) SO make admit to achieve high removal percentage (98%) and high adsorption capacity (50.25 mg g(-)(1)). A good agreement between experimental and predicted data in this study was observed. The experimental equilibrium data fitting to Langmuir, Freundlich, Tempkin and Dubinin-Radushkevich models show that the Langmuir model is a good and suitable model for evaluation and the actual behavior of adsorption. Kinetic evaluation of experimental data showed that the adsorption processes followed well pseudo-second-order and intraparticle diffusion models.

  18. Experimental design based response surface methodology optimization of ultrasonic assisted adsorption of safaranin O by tin sulfide nanoparticle loaded on activated carbon

    NASA Astrophysics Data System (ADS)

    Roosta, M.; Ghaedi, M.; Daneshfar, A.; Sahraei, R.

    2014-03-01

    In this research, the adsorption rate of safranine O (SO) onto tin sulfide nanoparticle loaded on activated carbon (SnS-NPAC) was accelerated by the ultrasound. SnS-NP-AC was characterized by different techniques such as SEM, XRD and UV-Vis measurements. The present results confirm that the ultrasound assisted adsorption method has remarkable ability to improve the adsorption efficiency. The influence of parameters such as the sonication time, adsorbent dosage, pH and initial SO concentration was examined and evaluated by central composite design (CCD) combined with response surface methodology (RSM) and desirability function (DF). Conducting adsorption experiments at optimal conditions set as 4 min of sonication time, 0.024 g of adsorbent, pH 7 and 18 mg L-1 SO make admit to achieve high removal percentage (98%) and high adsorption capacity (50.25 mg g-1). A good agreement between experimental and predicted data in this study was observed. The experimental equilibrium data fitting to Langmuir, Freundlich, Tempkin and Dubinin-Radushkevich models show that the Langmuir model is a good and suitable model for evaluation and the actual behavior of adsorption. Kinetic evaluation of experimental data showed that the adsorption processes followed well pseudo-second-order and intraparticle diffusion models.

  19. Removal of Cr(VI) from low-temperature micro-polluted surface water by tannic acid immobilized powdered activated carbon.

    PubMed

    Li, Weiguang; Gong, Xujin; Li, Xin; Zhang, Duoying; Gong, Hainan

    2012-06-01

    In this study, food-grade tannic acid-immobilized powdered activated carbon (TA-PAC) was prepared, and adsorption of Cr(VI) (0.500 mg/L) onto TA-PAC as a function of pH, contact time, adsorption capacities and adsorption isotherms at 280 K was investigated. The results indicated that the immobilization process introduced abundant acid functional groups. The adsorption capacity of TA-PAC was found to be pH-dependent, and the optimal pH value was found to be 4.0. The equilibrium time was 240 min for TA-PAC. Adsorption data for total chromium were modeled using both two-parameter and three-parameter isotherm models. Freundlich and linear forms of three-parameter models yielded the best results for all of the data. Desorption studies of immobilized material suggested that the immobilization of food-grade tannic acid is steady. The adsorption mechanism of Cr(VI) on TA-PAC was assumed to be a comprehensive process consisting of surface reduction of Cr(VI), esterification between catechol and chromate, and ion exchange.

  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. Ellipsometric and Electrochemical Characterization of Charge Transport in Electroactive Polymers and of the Surface Phase Produced by Electrochemical Activation of Glassy Carbon Electrodes

    NASA Astrophysics Data System (ADS)

    Kepley, Larry Joe

    1990-01-01

    In situ ellipsometry was used to study the electrodeposition of polymer films formed by oxidation of bipyrazine, polyvinylferrocene (PVF), and aniline; the deposition of a viologen-containing siloxane polymer (PQ^{2+/+}) formed by electroreduction of N,N^' -bis (-3-(trimethoxysilyl)propyl) -4,4^ '-bipyridinium dichloride (I) solutions and by spin-casting solutions of I; and the oxidation-dependent swelling of spin-cast films of two structurally similar, ferrocene-containing polyamides. Electrodeposited films displayed good optical characteristics (i.e., high reflectivity, uniform coverage, and homogeneity) for thicknesses up to 400 nm in some cases. Nonideal illipsometric behavior was observed when film morphology varied with film growth. The complex refractive index, film thickness, and the viologen and ferrocene concentrations in the films were measured as a function of oxidation state, both during depositions and after transferring coated-electrodes into blank electrolyte solutions. The voltammetry of the redox polymers was studied and charge-transport modeled by finite -difference simulations of charge diffusion and diffusion coupled to dimerization/monomerization reactions. Equations were derived for linear-sweep voltammetry of a reversible couple in equilibrium with its dimer in a thin-layer cell. Ellipsometric data during electrolysis of the redox films by potential sweeps and steps were compared to theoretical curves for diffusional transport to determine the mechanism of charge transport and to optically measure its rate. The influence of redox-induced thickness changes and solvent sorption on charge transport and voltammetric behavior is described. The electrochemical activation of glassy carbon electrodes for electrolysis of aromatic molecules, such as catechol and hydroquinone, was studied by combined ellipsometric and voltammetric measurements. Ellipsometry was used to detect the anodic growth of nearly transparent layer which activated the surface. X

  2. CARBON SEQUESTRATION SURFACE MINE LANDS

    SciTech Connect

    Donald H. Graves

    2003-05-06

    An authorized budget was unavailable during this first 3-month working period of this project. Our ability to use the $100K that DOE had dedicated to the project was frustrated by the internal problem of getting an account number issued to bill our expenses to. This has delayed the initiation of a portion of the tasks to be performed. However, enough has been accomplished to allow the project to meet the first years planting goals. This will also allow the initiation of several start-up activities that could not have been possible without established tree plantations.

  3. Preparation of binderless activated carbon monolith from pre-carbonization rubber wood sawdust by controlling of carbonization and activation condition

    NASA Astrophysics Data System (ADS)

    Taer, E.; Deraman, M.; Taslim, R.; Iwantono

    2013-09-01

    Binderless activated carbon monolith (ACM) was prepared from pre-carbonized rubber wood sawdust (RWSD). The effect of the carbonization temperature (400, 500, 600, 700, 800 dan 900 °C) on porosity characteristic of the ACM have been studied. The optimum carbonization temperature for obtaining ACM with high surface area of 600 °C with CO2 activation at 800 °C for one hour. At this condition, the surface area as high as 733 m2 g-1 could be successfully obtained. By improved the activation temperature at 900 °C for 2.5 h, it was found that the surface area of 860 m2 g-1. For this condition, the ACM exhibit the specific capacitance of 90 F g-1. In addition the termogravimertic (TG)-differential termografimertic (DTG) and field emission scanning electron microscope (FESEM) measurement were also performed on the ACMs and the result has been studied. Finally, it was conclude that the high surface area of ACM from RWSD could be produced by proper selections of carbonization and activation condition.

  4. Preparation of activated carbons from bituminous coal pitches

    NASA Astrophysics Data System (ADS)

    Gañan, J.; González-García, C. M.; González, J. F.; Sabio, E.; Macías-García, A.; Díaz-Díez, M. A.

    2004-11-01

    High-porosity carbons were prepared from bituminous coal pitches by combining chemical and physical activation. The chemical activation process consisted of potassium hydroxide impregnation followed by carbonization in nitrogen atmosphere. The effect of the KOH impregnation ratio on the surface area and pore volumes evolution of the carbons derived from mesophase pitch was studied. The optimum KOH:pitch ratio was fixed to realize a physical activation process in order to increase the textural parameters of the KOH-activated carbons. Physical activation was performed by carbonizing the KOH-activated carbons followed by gasifying with air. The influence of the carbonization temperature and the residence time of the gasification with air were explored to optimize those preparation parameters.

  5. Carbon Sequestration on Surface Mine Lands

    SciTech Connect

    Donald H. Graves; Christopher Barton; Richard Sweigard; Richard Warner

    2005-10-02

    During this quarter a general forest monitoring program was conducted to measure treatment effects on above ground and below ground carbon C and Nitrogen (N) pools for the tree planting areas. Detailed studies to address specific questions pertaining to Carbon cycling was initiated with the development of plots to examine the influence of mycorrhizae, spoil chemical and mineralogical properties, and use of amendment on forest establishment and carbon sequestration. Efforts continued during this period to examine decomposition and heterotrophic respiration on C cycling in the reforestation plots. Projected climate change resulting from elevated atmospheric carbon dioxide has given rise to various strategies to sequester carbon in various terrestrial ecosystems. Reclaimed surface mine soils present one such potential carbon sink where traditional reclamation objectives can complement carbon sequestration. New plantings required the modification and design and installation on monitoring equipment. Maintenance and data monitoring on past and present installations are a continuing operation. The Department of Mining Engineering continued the collection of penetration resistance, penetration depth, and bulk density on both old and new treatment areas. Data processing and analysis is in process for these variables. Project scientists and graduate students continue to present results at scientific meetings, tours and field days presentations of the research areas are being conducted on a request basis.

  6. Interaction of Surface Modified Carbon Nanotubes with Supercritical Carbon Dioxide

    NASA Astrophysics Data System (ADS)

    Baysal, Nihat; Unsal, Banu; Ozisik, Rahmi

    2006-03-01

    The properties of carbon nanotube (CNT)-polymer nanocomposites are far below than those calculated, mainly due to poor dispersion or interface quality. This is particularly difficult for single walled carbon nanotubes (SWNTs) as they tend to form bundles or ropes that are difficult to exfoliate. Supercritical fluid (SCF) assisted processing is one of the methods that can be used to exfoliate/disperse CNTs along with modifiying the interface of the CNTs. Molecular dynamics simulations were performed to understand how the surface modifiers behave near SWNT surface with and without the presence of SCF molecules. It is also important to understand the diffusivity of SCF molecules between SWNT bundles and the effect of surface modifiers on diffusion. Octane and n-perflourooctane molecules were used as surface modifiers with varying tethering density and carbon dioxide (CO2) was chosen as the SCF. Results showed that the system with highest number of n-perfluorooctanes presented the highest degree of success in separating the SWNTs in the presence of CO2.

  7. Apparatus for in situ cleaning of carbon contaminated surfaces

    DOEpatents

    Klebanoff, Leonard E.; Grunow, Philip; Graham, Jr., Samuel

    2004-08-10

    Activated gaseous species generated adjacent a carbon contaminated surface affords in-situ cleaning. A device for removing carbon contamination from a surface of the substrate includes (a) a housing defining a vacuum chamber in which the substrate is located; (b) a source of gaseous species; and (c) a source of electrons that are emitted to activate the gaseous species into activated gaseous species. The source of electrons preferably includes (i) a filament made of a material that generates thermionic electron emissions; (ii) a source of energy that is connected to the filament; and (iii) an electrode to which the emitted electrons are attracted. The device is particularly suited for photolithography systems with optic surfaces, e.g., mirrors, that are otherwise inaccessible unless the system is dismantled.

  8. 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.

  9. 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.

  10. Simultaneous ultrasound-assisted ternary adsorption of dyes onto copper-doped zinc sulfide nanoparticles loaded on activated carbon: optimization by response surface methodology.

    PubMed

    Asfaram, Arash; Ghaedi, Mehrorang; Hajati, Shaaker; Goudarzi, Alireza; Bazrafshan, Ali Akbar

    2015-06-15

    The simultaneous and competitive ultrasound-assisted removal of Auramine-O (AO), Erythrosine (Er) and Methylene Blue (MB) from aqueous solutions were rapidly performed onto copper-doped zinc sulfide nanoparticles loaded on activated carbon (ZnS:Cu-NP-AC). ZnS:Cu nanoparticles were studied by FESEM, XRD and TEM. First, the effect of pH was optimized in a one-at-a-time procedure. Then the dependency of dyes removal percentage in their ternary solution on the level and magnitude of variables such as sonication time, initial dyes concentrations and adsorbent dosage was fully investigated and optimized by central composite design (CCD) under response surface methodology (RSM) as well as by regarding desirability function (DF) as a good and general criterion. The good agreement found between experimental and predicted values supports and confirms the suitability of the present model to predict adsorption state. The applied ultrasound strongly enhanced mass transfer process and subsequently performance. Hence, a small amount of the adsorbent (0.04 g) was capable to remove high percentage of dyes, i.e. 100%, 99.6% and 100% for MB, AO and Er, respectively, in very short time (2.5 min). The experimental equilibrium data fitting to Langmuir, Freundlich, Temkin and Dubinin-Radushkevich models showed that the Langmuir model applies well for the evaluation and description of the actual behavior of adsorption. The small amount of proposed adsorbent (0.015 g) was applicable for successful removal of dyes (RE>99.0%) in short time (2.5 min) with high adsorption capacity in single component system (123.5 mg g(-1) for MB, 123 mg g(-1) for AO and 84.5 mg g(-1) for Er). Kinetics evaluation of experiments at various time intervals reveals that adsorption processes can be well predicated and fitted by pseudo-second-order and Elovich models.

  11. Simultaneous ultrasound-assisted ternary adsorption of dyes onto copper-doped zinc sulfide nanoparticles loaded on activated carbon: Optimization by response surface methodology

    NASA Astrophysics Data System (ADS)

    Asfaram, Arash; Ghaedi, Mehrorang; Hajati, Shaaker; Goudarzi, Alireza; Bazrafshan, Ali Akbar

    2015-06-01

    The simultaneous and competitive ultrasound-assisted removal of Auramine-O (AO), Erythrosine (Er) and Methylene Blue (MB) from aqueous solutions were rapidly performed onto copper-doped zinc sulfide nanoparticles loaded on activated carbon (ZnS:Cu-NP-AC). ZnS:Cu nanoparticles were studied by FESEM, XRD and TEM. First, the effect of pH was optimized in a one-at-a-time procedure. Then the dependency of dyes removal percentage in their ternary solution on the level and magnitude of variables such as sonication time, initial dyes concentrations and adsorbent dosage was fully investigated and optimized by central composite design (CCD) under response surface methodology (RSM) as well as by regarding desirability function (DF) as a good and general criterion. The good agreement found between experimental and predicted values supports and confirms the suitability of the present model to predict adsorption state. The applied ultrasound strongly enhanced mass transfer process and subsequently performance. Hence, a small amount of the adsorbent (0.04 g) was capable to remove high percentage of dyes, i.e. 100%, 99.6% and 100% for MB, AO and Er, respectively, in very short time (2.5 min). The experimental equilibrium data fitting to Langmuir, Freundlich, Temkin and Dubinin-Radushkevich models showed that the Langmuir model applies well for the evaluation and description of the actual behavior of adsorption. The small amount of proposed adsorbent (0.015 g) was applicable for successful removal of dyes (RE > 99.0%) in short time (2.5 min) with high adsorption capacity in single component system (123.5 mg g-1 for MB, 123 mg g-1 for AO and 84.5 mg g-1 for Er). Kinetics evaluation of experiments at various time intervals reveals that adsorption processes can be well predicated and fitted by pseudo-second-order and Elovich models.

  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. Surface analyses of carbon fibers produced from polyacrylonitrile fibers at low carbonization temperatures

    NASA Technical Reports Server (NTRS)

    Cagliostro, D. E.

    1983-01-01

    A process for producing carbon fibers from polyacrylonitrile at low carbonization temperatures was studied. The bulk and surface properties of fibers obtained after reaction with benzoic acid, air and carbonizing in nitrogen or a dilute acetylene atmosphere are discussed. All fiber products had different surface and internal compositions. Samples produced at temperatures up to 950 C and carbonized in nitrogen contained substantial quantities of nitrogen and oxygen at the surface. During carbonization, the surface nitrogen converted into two new forms, possibly nitrile and an azo or a new carbon-nitrogen bond. Samples carbonized in acetylene contained a carbon-rich surface stable to oxidation.

  14. The biomass derived activated carbon for supercapacitor

    NASA Astrophysics Data System (ADS)

    Senthilkumar, S. T.; Selvan, R. Kalai; Melo, J. S.

    2013-06-01

    In this work, the activated carbon was prepared from biowaste of Eichhornia crassipes by chemical activation method using KOH as the activating agent at various carbonization temperatures (600 °C, 700 °C and 800 °C). The disordered nature, morphology and surface functional groups of ACs were examined by XRD, SEM and FT-IR. The electrochemical properties of AC electrodes were studied in 1M H2SO4 in the potential range of -0.2 to 0.8 V using cyclic voltammetry (CV), galvanostatic charge-discharge and electrochemical impedance spectroscopy (EIS) techniques in a three electrode system. Subsequently, the fabricated supercapacitor using AC electrode delivered the higher specific capacitance and energy density of 509 F/g at current density of 1 mA/cm2 and 17 Wh/kg at power density of 0.416 W/g.

  15. 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

  16. 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.

  17. Solvent-regenerated activated carbon

    SciTech Connect

    McLaughlin, H. )

    1988-07-01

    This report summarizes the results of a University/Industry research project, sponsored by the New York State Energy Research and Development Authority and Fluids Design Corporation. The research project studied the solvent regeneration of activated carbon. Activate carbon was used to remove trace organics from aqueous streams, then regenerated by desorbing the adsorbates with organic solvents. The project included a survey of the potential applications in New York State industries, fundamental research on the adsorption/desorption phenomena, and design of a full-scale process. The economics of the full-scale process were evaluated and compared to alternate available technologies. The result of this work is a versatile process with attractive economics. A wide range of adsorbates and solvents were found to be acceptable for this process. The design methodologies are developed and the techniques for evaluating a new application are delineated. 13 refs., 12 figs., 4 tabs.

  18. Carbon Dioxide Chemistry on Titan's Surface

    NASA Astrophysics Data System (ADS)

    Hodyss, R. P.; Cable, M. L.; Malaska, M. J.; Vu, T. H.

    2015-12-01

    The surfaces of the moons of the outer Solar System are usually considered too cold (30-100 K) for significant chemistry to occur without the input of energy from exogenic sources (such as charged particles or VUV irradiation). In particular, Titan's thick atmosphere prevents significant amounts of high energy radiation from reaching the surface, limiting opportunities for surface chemical reactivity. Recently, we have identified carbamation, the reaction of carbon dioxide with primary amines to form carbamic acids, as a reaction that could occur thermally on Titan's surface. Amines should be present on Titan's surface, formed by photochemical reactions of N2 and CH4 in the upper atmosphere, and amine-containing molecules have been detected as a component of laboratory tholins made in terrestrial laboratories. There is some spectral evidence that CO2 is present on the surface, and CO2 has been definitively identified in the atmosphere. We use a combination of micro-Raman spectroscopy and UHV FTIR spectroscopy to examine the reaction products and kinetics of the carbamation reaction for a variety of primary amines. The reaction occurs readily at Titan surface temperatures (94 K), and leads to both carbamic acids and ammonium carbamate salts. Our kinetic data can be used to estimate the lifetime of CO2 on Titan's surface, and thus constrain the age of possible CO2-bearing cryovolcanic deposits.

  19. 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.

  20. Modified Activated Carbon Perchlorate Sorbents

    DTIC Science & Technology

    2007-01-25

    nitrosodimethylamine precursors in municipal wastewater treatment plants. Environ. Sci. Technol., 2004. 38: p. 1445-1454. 15. Shmidt, V., K. Rybakov...Engineering and Management, 1994. 141: p. 12. 33. Walker, G. and L. Weatherley, Biological Activated Carbon Treatment of Industrial Wastewater in... Treatment with Ammonia (NAC), Urea-formaldehyde Resin (UAC), and Hydrogen (HAC). Data are Indicated by the Symbol and Least Squares Fit of the Langmuir

  1. Risk Assessment of Carbon Fiber Composite in Surface Transportation

    NASA Technical Reports Server (NTRS)

    Hathaway, W. T.; Hergenrother, K. M.

    1980-01-01

    The vulnerability of surface transportation to airborne carbon fibers and the national risk associated with the potential use of carbon fibers in the surface transportation system were evaluated. Results show airborne carbon fibers may cause failure rates in surface transportation of less than one per year by 1995. The national risk resulting from the use of carbon fibers in the surface transportation system is discussed.

  2. 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.

  3. Activated carbon briquettes from biomass materials.

    PubMed

    Amaya, Alejandro; Medero, Natalia; Tancredi, Néstor; Silva, Hugo; Deiana, Cristina

    2007-05-01

    Disposal of biomass wastes, produced in different agricultural activities, is frequently an environmental problem. A solution for such situation is the recycling of these residues for the production of activated carbon, an adsorbent which has several applications, for instance in the elimination of contaminants. For some uses, high mechanical strength and good adsorption characteristics are required. To achieve this, carbonaceous materials are conformed as pellets or briquettes, in a process that involves mixing and pressing of char with adhesive materials prior to activation. In this work, the influence of the operation conditions on the mechanical and surface properties of briquettes was studied. Eucalyptus wood and rice husk from Uruguay were used as lignocellulosic raw materials, and concentrated grape must from Cuyo Region-Argentina, as a binder. Different wood:rice and solid:binder ratios were used to prepare briquettes in order to study their influence on mechanical and surface properties of the final products.

  4. Role of heteroatoms in activated carbon for removal of hexavalent chromium from wastewaters.

    PubMed

    Valix, M; Cheung, W H; Zhang, K

    2006-07-31

    Heteroatoms are elements including sulfur, nitrogen, oxygen and hydrogen which are found on the surface of activated carbons. This study investigated the surface modification arising from heteroatoms bonding to carbon aromatic rings within the activated carbon and their corresponding influence on the chromium adsorption process. Activated carbons were prepared from bagasse by physical. Chromium removal capacities of these activated carbons by adsorption and reduction were determined. Models which related the chromium adsorption and reduction capacities of activated carbons to carbon acidity and heteroatom site concentrations were established using multi-variable linear regression method. It was found the individual heteroatoms contributed separately to the basicity of the carbon which in turn determined the mechanism by which chromium was removed from solution. The surface areas of the carbons were also observed to influence the adsorption and reduction of chromium. These understandings provide the fundamental method of optimising chromium removal through suitable control of carbon surface chemistry and textural properties.

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

    PubMed

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

    2011-04-01

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

  6. Surface analysis of carbon black waste materials from tire residues

    NASA Astrophysics Data System (ADS)

    Lee, W. H.; Kim, J. Y.; Ko, Y. K.; Reucroft, P. J.; Zondlo, J. W.

    1999-03-01

    X-ray photoelectron spectroscopy (XPS) has been used to obtain surface chemical state information on two carbon black waste materials in terms of the surface element distribution/concentration and chemical structure. Small amounts of sulfur in the form of CS 2 were detected on the surface (less than 1.7 mass %). C-H/C-C was the major carbon functional component on the surface of carbon black samples but other functional forms of carbon were also present such as CO and C-O. The surface of the carbon black obtained from a hydropyrolysis process was highly oxidized primarily in the form of carbon based oxygen groups. On the other hand, surface oxygen atoms on the surface of the carbon black obtained from a pyrolysis process in the absence of H 2 were in the form of both metal oxides and carbon based oxygen groups.

  7. 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.

  8. 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.

  9. Gold Nanoparticles Deposited on Surface Modified Carbon Xerogels as Reusable Catalysts for Cyclohexane C-H Activation in the Presence of CO and Water.

    PubMed

    Ribeiro, Ana Paula da Costa; Martins, Luísa Margarida Dias Ribeiro de Sousa; Carabineiro, Sónia Alexandra Correia; Figueiredo, José Luís; Pombeiro, Armando José Latourrette

    2017-04-09

    The use of gold as a promotor of alkane hydrocarboxylation is reported for the first time. Cyclohexane hydrocarboxylation to cyclohexanecarboxylic acid (up to 55% yield) with CO, water, and peroxodisulfate in a water/acetonitrile medium at circa 50 °C has been achieved in the presence of gold nanoparticles deposited by a colloidal method on a carbon xerogel in its original form (CX), after oxidation with HNO₃ (-ox), or after oxidation with HNO₃ and subsequent treatment with NaOH (-ox-Na). Au/CX-ox-Na behaves as re-usable catalyst maintaining its initial activity and selectivity for at least seven consecutive cycles. Green metric values of atom economy or carbon efficiency also attest to the improvement brought by this novel catalytic system to the hydrocarboxylation of cyclohexane.

  10. Iron cycling at corroding carbon steel surfaces.

    PubMed

    Lee, Jason S; McBeth, Joyce M; Ray, Richard I; Little, Brenda J; Emerson, David

    2013-01-01

    Surfaces of carbon steel (CS) exposed to mixed cultures of iron-oxidizing bacteria (FeOB) and dissimilatory iron-reducing bacteria (FeRB) in seawater media under aerobic conditions were rougher than surfaces of CS exposed to pure cultures of either type of microorganism. The roughened surface, demonstrated by profilometry, is an indication of loss of metal from the surface. In the presence of CS, aerobically grown FeOB produced tight, twisted helical stalks encrusted with iron oxides. When CS was exposed anaerobically in the presence of FeRB, some surface oxides were removed. However, when the same FeOB and FeRB were grown together in an aerobic medium, FeOB stalks were less encrusted with iron oxides and appeared less tightly coiled. These observations suggest that iron oxides on the stalks were reduced and solubilized by the FeRB. Roughened surfaces of CS and denuded stalks were replicated with culture combinations of different species of FeOB and FeRB under three experimental conditions. Measurements of electrochemical polarization resistance established different rates of corrosion of CS in aerobic and anaerobic media, but could not differentiate rate differences between sterile controls and inoculated exposures for a given bulk concentration of dissolved oxygen. Similarly, total iron in the electrolyte could not be used to differentiate treatments. The experiments demonstrate the potential for iron cycling (oxidation and reduction) on corroding CS in aerobic seawater media.

  11. High surface area silicon carbide-coated carbon aerogel

    DOEpatents

    Worsley, Marcus A; Kuntz, Joshua D; Baumann, Theodore F; Satcher, Jr, Joe H

    2014-01-14

    A metal oxide-carbon composite includes a carbon aerogel with an oxide overcoat. The metal oxide-carbon composite is made by providing a carbon aerogel, immersing the carbon aerogel in a metal oxide sol under a vacuum, raising the carbon aerogel with the metal oxide sol to atmospheric pressure, curing the carbon aerogel with the metal oxide sol at room temperature, and drying the carbon aerogel with the metal oxide sol to produce the metal oxide-carbon composite. The step of providing a carbon aerogel can provide an activated carbon aerogel or provide a carbon aerogel with carbon nanotubes that make the carbon aerogel mechanically robust. Carbon aerogels can be coated with sol-gel silica and the silica can be converted to silicone carbide, improved the thermal stability of the carbon aerogel.

  12. Degradation characteristics of 17beta-estradiol by ozone treatment with activated carbon.

    PubMed

    Kawasaki, Naohito; Ogata, Fumihiko; Yamaguchi, Isao; Tominaga, Hisato

    2009-01-01

    The present study investigates (1) ozone treatment, (2) adsorption treatment using activated carbon treatment, and (3) ozone treatment with activated carbon for their efficacy in removing 17beta-estradiol (E2) present in an aqueous solution. Both ozone and activated carbon treatments for 20 min were effective in removing E2 (initial concentration, 100 mg/L). However, both treatments have been used for two processes, and the disposal time with these treatments is more than that of another treatment. In this study, ozone treatment with activated carbon was investigated with regard to the percentage of E2 removal, pH, and chemical oxygen demand (COD). The physical and chemical characteristics of the activated carbon surface were modified due to the ozone treatment: the surface was oxidized by ozone. The surface of activated carbon exhibited polarity groups and became porous after ozone treatment. The amount of E2 adsorbed onto the ozone-treated activated carbon surface was similar to that adsorbed onto the untreated activated carbon surface. The percentage of E2 removal by ozone treatment with activated carbon was greater than that by ozone treatment alone. Moreover, the rate of E2 removal by ozone treatment with activated carbon was higher than that by ozone or activated carbon treatments alone. Ozone with activated carbon treatment may be used for the removal of E2. However, this ozone treatment for the degradation of E2 may have a greater COD than that in the case of activated carbon treatment alone.

  13. Microscopic Study of Carbon Surfaces Interacting with High Carbon Ferromanganese Slag

    NASA Astrophysics Data System (ADS)

    Safarian, Jafar; Kolbeinsen, Leiv

    2015-02-01

    The interaction of carbon materials with molten slags occurs in many pyro-metallurgical processes. In the production of high carbon ferromanganese in submerged arc furnace, the carbothermic reduction of MnO-containing silicate slags yields the metal product. In order to study the interaction of carbon with MnO-containing slags, sessile drop wettability technique is employed in this study to reduce MnO from a molten slag drop by carbon substrates. The interfacial area on the carbon substrate before and after reaction with slag is studied by scanning electron microscope. It is indicated that no Mn metal particles are found at the interface through the reduction of the MnO slag. Moreover, the reduction of MnO occurs through the contribution of Boudouard reaction and it causes carbon consumption in particular active sites at the interface, which generate carbon degradation and open pore growth at the interface. It is shown that the slag is fragmented to many micro-droplets at the reaction interface, potentially due to the effect on the interfacial energies of a provisional liquid Mn thin film. The rapid reduction of these slag micro-droplets affects the carbon surface with making deep micro-pores. A mechanism for the formation of slag micro-droplets is proposed, which is based on the formation of provisional micro thin films of liquid Mn at the interface.

  14. Microscopic Study of Carbon Surfaces Interacting with High Carbon Ferromanganese Slag

    NASA Astrophysics Data System (ADS)

    Safarian, Jafar; Kolbeinsen, Leiv

    2014-09-01

    The interaction of carbon materials with molten slags occurs in many pyro-metallurgical processes. In the production of high carbon ferromanganese in submerged arc furnace, the carbothermic reduction of MnO-containing silicate slags yields the metal product. In order to study the interaction of carbon with MnO-containing slags, sessile drop wettability technique is employed in this study to reduce MnO from a molten slag drop by carbon substrates. The interfacial area on the carbon substrate before and after reaction with slag is studied by scanning electron microscope. It is indicated that no Mn metal particles are found at the interface through the reduction of the MnO slag. Moreover, the reduction of MnO occurs through the contribution of Boudouard reaction and it causes carbon consumption in particular active sites at the interface, which generate carbon degradation and open pore growth at the interface. It is shown that the slag is fragmented to many micro-droplets at the reaction interface, potentially due to the effect on the interfacial energies of a provisional liquid Mn thin film. The rapid reduction of these slag micro-droplets affects the carbon surface with making deep micro-pores. A mechanism for the formation of slag micro-droplets is proposed, which is based on the formation of provisional micro thin films of liquid Mn at the interface.

  15. Production and characterization of lignocellulosic biomass-derived activated carbon.

    PubMed

    Namazi, A B; Jia, C Q; Allen, D G

    2010-01-01

    The goal of this work is to establish the technical feasibility of producing activated carbon from pulp mill sludges. KOH chemical activation of four lignocellulosic biomass materials, two sludges from pulp mills, one sludge for a linerboard mill, and cow manure, were investigated experimentally, with a focus on the effects of KOH/biomass ratio (1/1, 1.5/1 and 2/1), activation temperature (400-600 °C) and activation time (1 to 2 h) on the development of porosity. The activation products were characterized for their physical and chemical properties using a surface area analyzer, scanning electron microscopy and Fourier transform infrared spectroscopy. Experiments were carried out to establish the effectiveness of the lignocellulosic biomass-derived activated carbon in removing methylene blue (MB), a surrogate of large organic molecules. The results show that the activated carbon are highly porous with specific surface area greater than 500 m²/g. The yield of activated carbon was greater than the percent of fixed carbon in the dry sludge, suggesting that the activation process was able to capture a substantial amount of carbon from the organic matter in the sludge. While 400 °C was too low, 600 °C was high enough to sustain a substantial rate of activation for linerboard sludge. The KOH/biomass ratio, activation temperature and time all play important roles in pore development and yield control, allowing optimization of the activation process. MB adsorption followed a Langmuir isotherm for all four activated carbon, although the adsorption capacity of NK-primary sludge-derived activated carbon was considerably lower than the rest, consistent with its lower specific surface area.

  16. Surface chemistry of carbon dioxide revisited

    NASA Astrophysics Data System (ADS)

    Taifan, William; Boily, Jean-François; Baltrusaitis, Jonas

    2016-12-01

    This review discusses modern developments in CO2 surface chemistry by focusing on the work published since the original review by H.J. Freund and M.W. Roberts two decades ago (Surface Science Reports 25 (1996) 225-273). It includes relevant fundamentals pertaining to the topics covered in that earlier review, such as conventional metal and metal oxide surfaces and CO2 interactions thereon. While UHV spectroscopy has routinely been applied for CO2 gas-solid interface analysis, the present work goes further by describing surface-CO2 interactions under elevated CO2 pressure on non-oxide surfaces, such as zeolites, sulfides, carbides and nitrides. Furthermore, it describes additional salient in situ techniques relevant to the resolution of the interfacial chemistry of CO2, notably infrared spectroscopy and state-of-the-art theoretical methods, currently used in the resolution of solid and soluble carbonate species in liquid-water vapor, liquid-solid and liquid-liquid interfaces. These techniques are directly relevant to fundamental, natural and technological settings, such as heterogeneous and environmental catalysis and CO2 sequestration.

  17. Evidence for Carbonate Surface Complexation during Forsterite Carbonation in Wet Supercritical Carbon Dioxide

    SciTech Connect

    Loring, John S.; Chen, Jeffrey; Benezeth Ep Gisquet, Pascale; Qafoku, Odeta; Ilton, Eugene S.; Washton, Nancy M.; Thompson, Christopher J.; Martin, Paul F.; McGrail, B. Peter; Rosso, Kevin M.; Felmy, Andrew R.; Schaef, Herbert T.

    2015-07-14

    Continental flood basalts are attractive formations for geologic sequestration of carbon dioxide because of their reactive divalent-cation containing silicates, such as forsterite (Mg2SiO4), suitable for long-term trapping of CO2 mineralized as metal carbonates. The goal of this study was to investigate at a molecular level the carbonation products formed during the reaction of forsterite with supercritical CO2 (scCO2) as a function of the concentration of H2O adsorbed to the forsterite surface. Experiments were performed at 50 °C and 90 bar using an in situ IR titration capability, and post-reaction samples were examined by ex situ techniques, including SEM, XPS, FIB-TEM, TGA-MS, and MAS-NMR. Carbonation products and reaction extents varied greatly with adsorbed H2O. We show for the first time evidence of Mg-carbonate surface complexation under wet scCO2 conditions. Carbonate is found to be coordinated to Mg at the forsterite surface in a predominately bidentate fashion at adsorbed H2O concentrations below 27 µmol/m2. Above this concentration and up to 76 µmol/m2, monodentate coordinated complexes become dominant. Beyond a threshold adsorbed H2O concentration of 76 µmol/m2, crystalline carbonates continuously precipitate as magnesite, and the particles that form are hundreds of times larger than the estimated thicknesses of the adsorbed water films of about 7 to 15 Å. At an applied level, these results suggest that mineral carbonation in scCO2 dominated fluids near the wellbore and adjacent to caprocks will be insignificant and limited to surface complexation, unless adsorbed H2O concentrations are high enough to promote crystalline carbonate formation. At a fundamental level, the surface complexes and their dependence on adsorbed H2O concentration give insights regarding forsterite dissolution processes and magnesite nucleation and growth.

  18. 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.

  19. Potential for carbon adsorption on concrete: surface XPS analyses.

    PubMed

    Haselbach, Liv M; Ma, Shuguo

    2008-07-15

    The concrete industry is a contributor to the global carbon cycle particularly with respect to the contribution of carbon dioxide in the manufacturing of cement (calcination). The reverse reaction of carbonation is known to occur in concrete, but is usually limited to exterior surfaces exposed to carbon dioxide and humidity in the air. As alternate concrete uses expand which have more surface area, such as crushed concrete for recycling, it is important to understand surface adsorption of carbon dioxide and the positive impacts it might have on the carbon cycle. X-ray photoelectron spectroscopy (XPS) is used in this study to evaluate carbon species on hydrated cement mortar surfaces. Initial estimates for carbon absorption in concrete using othertechniques predictthe potential for carbonate species to be a fraction of the calcination stoichiometric equivalent The XPS results indicate that there is a rapid and substantial uptake of carbon dioxide on the surfaces of these mortars, sometimes exceeding the calcination stoichiometric equivalents, indicative of carbon dioxide surface complexation species. On pure calcite, the excess is on the order of 30%. This accelerated carbon dioxide surface adsorption phenomenon may be importantfor determining novel and effective carbon sequestration processes using recycled concrete.

  20. Apparatus and process for the surface treatment of carbon fibers

    SciTech Connect

    Paulauskas, Felix Leonard; Ozcan, Soydan; Naskar, Amit K.

    2016-05-17

    A method for surface treating a carbon-containing material in which carbon-containing material is reacted with decomposing ozone in a reactor (e.g., a hollow tube reactor), wherein a concentration of ozone is maintained throughout the reactor by appropriate selection of at least processing temperature, gas stream flow rate, reactor dimensions, ozone concentration entering the reactor, and position of one or more ozone inlets (ports) in the reactor, wherein the method produces a surface-oxidized carbon or carbon-containing material, preferably having a surface atomic oxygen content of at least 15%. The resulting surface-oxidized carbon material and solid composites made therefrom are also described.

  1. Adsorption of aromatic compounds by carbonaceous adsorbents: a comparative study on granular activated carbon, activated carbon fiber, and carbon nanotubes.

    PubMed

    Zhang, Shujuan; Shao, Ting; Kose, H Selcen; Karanfil, Tanju

    2010-08-15

    Adsorption of three aromatic organic compounds (AOCs) by four types of carbonaceous adsorbents [a granular activated carbon (HD4000), an activated carbon fiber (ACF10), two single-walled carbon nanotubes (SWNT, SWNT-HT), and a multiwalled carbon nanotube (MWNT)] with different structural characteristics but similar surface polarities was examined in aqueous solutions. Isotherm results demonstrated the importance of molecular sieving and micropore effects in the adsorption of AOCs by carbonaceous porous adsorbents. In the absence of the molecular sieving effect, a linear relationship was found between the adsorption capacities of AOCs and the surface areas of adsorbents, independent of the type of adsorbent. On the other hand, the pore volume occupancies of the adsorbents followed the order of ACF10 > HD4000 > SWNT > MWNT, indicating that the availability of adsorption site was related to the pore size distributions of the adsorbents. ACF10 and HD4000 with higher microporous volumes exhibited higher adsorption affinities to low molecular weight AOCs than SWNT and MWNT with higher mesopore and macropore volumes. Due to their larger pore sizes, SWNTs and MWNTs are expected to be more efficient in adsorption of large size molecules. Removal of surface oxygen-containing functional groups from the SWNT enhanced adsorption of AOCs.

  2. Carbon Sequestration on Surface Mine Lands

    SciTech Connect

    Donald H. Graves; Christopher Barton; Bon Jun Koo; Richard Sweigard; Richard Warner

    2004-11-30

    The first quarter of 2004 was dedicated to tree planting activities in two locations in Kentucky. During the first year of this project there was not available mine land to plant in the Hazard area, so 107 acres were planted in the Martin County mine location. This year 120 acres were planted in the Hazard area to compensate for the prior year and an additional 57 acres were planted on Peabody properties in western Kentucky. Additional sets of special plots were established on each of these areas that contained 4800 seedlings each for carbon sequestration demonstrations. Plantings were also conducted to continue compaction and water quality studies on the newly established areas as well as continual measurements of the first year's plantings. Total plantings on this project now amount to 357 acres containing 245,960 seedlings. During the second quarter of this year monitoring systems were established for all the new research areas. Weather data pertinent to the research as well as hydrology and water quality monitoring continues to be conducted on all areas. Studies established to assess specific questions pertaining to carbon flux and the invasion of the vegetation by small mammals are being quantified. Experimental practices initiated with this research project will eventually allow for the planting on long steep slopes with loose grading systems and allow mountain top removal areas to be constructed with loose spoil with no grading of the final layers of rooting material when establishing trees for the final land use designation. Monitoring systems have been installed to measure treatment effects on both above and below ground carbon and nitrogen pools in the planting areas. Soil and tissue samples were collected from both years planting and analyses were conducted in the laboratory. Examination of decomposition and heterotropic respiration on carbon cycling in the reforestation plots continued during the reporting period. Entire planted trees were extracted

  3. Evidence for Carbonate Surface Complexation during Forsterite Carbonation in Wet Supercritical Carbon Dioxide

    SciTech Connect

    Loring, John S.; Chen, Jeffrey; Benezeth, Pascale; Qafoku, Odeta; Ilton, Eugene S.; Washton, Nancy M.; Thompson, Christopher J.; Martin, Paul F.; McGrail, B. Peter; Rosso, Kevin M.; Felmy, Andrew R.; Schaef, Herbert T.

    2015-06-16

    Continental flood basalts are attractive formations for geologic sequestration of carbon dioxide because of their reactive divalent-cation containing silicates, such as forsterite (Mg2SiO4), suitable for long-term trapping of CO2 mineralized as metal carbonates. The goal of this study was to investigate at a molecular level the carbonation products formed during the reaction of forsterite with supercritical CO2 (scCO2) as a function of the concentration of H2O adsorbed to the forsterite surface. Experiments were performed at 50 °C and 90 bar using an in situ IR titration capability, and post-reaction samples were examined by ex situ techniques, including SEM, XPS, FIB-TEM, TGA-MS, and MAS-NMR. Carbonation products and reaction extents varied greatly with adsorbed H2O. We show for the first time evidence of Mg-carbonate surface complexation under wet scCO2 conditions. Carbonate is found to be coordinated to Mg at the forsterite surface in a predominately bidentate fashion at adsorbed H2O concentrations below 27 µmol/m2. Above this concentration and up to 76 µmol/m2, monodentate coordinated complexes become dominant. Beyond a threshold adsorbed H2O concentration of 76 µmol/m2, crystalline carbonates continuously precipitate as magnesite, and the particles that form are hundreds of times larger than the estimated thicknesses of the adsorbed water films of about 7 to 15 Å. At an applied level, the implication of these results is that mineral trapping in scCO2 dominated fluids will be insignificant and limited to surface complexation unless adsorbed H2O concentrations are high enough to promote crystalline carbonate formation. At a fundamental level, the surface complexes and their dependence on adsorbed H2O concentration give insights regarding forsterite dissolution processes and magnesite nucleation and growth.

  4. Microbial Surfaces and their Effects on Carbonate Mineralization

    NASA Astrophysics Data System (ADS)

    Cappuccio, J. A.; Pillar, V. D.; Lui, G. V.; Ajo-Franklin, C.

    2011-12-01

    Geologic carbon dioxide sequestration, the underground storage of carbon dioxide (CO2), will be an essential component of climate change mitigation. Carbonate minerals are a promising form of stable CO2 storage, but their geologic formation is slow. Many microbes can increase the rate of carbonate mineral formation; however the mechanisms of such mineralization are largely unknown. Hypothesized mechanisms include metabolic processes that alter pH and supersaturation, as well as cell surface properties that induce mineral nucleation. This work systematically investigates these mechanisms by allowing calcium carbonate (CaCO3) to form in the presence or absence of microbes with various surfaces features included Escherichia coli, Synechocystis sp. PCC 6803, Caulobacter vibrioides, and Lysinibacilllus sphaericus. Surprisingly, formation of stable crystalline CaCO3 was accelerated by the presence of all microbes relative to abiotic solutions. This rate acceleration also occurred for metabolically inactive bacteria, indicating that metabolic activity was not the operating mechanism. Rather, since the CaCO3 crystals increased in number as the cell density increased, these results indicate that many bacterial species accelerate the nucleation of CaCO3 crystals. To understand the role of specific biomolecules on nucleation, we used genetic mutants with altered lipopolysaccharides (LPS) and crystalline surface layer proteins (S-layers). Bacterial surface charge and cation binding was assessed using zeta potential measurements and correlated to the bacterial surface chemistry and biomineralization experiments with varying Ca2+ concentrations. From these results, we postulate that the S-layer surfaces can selectively attract Ca2+ ions, serving as nucleation sites for CaCO3, thereby accelerating crystal formation. These observations provide substantive evidence for a non-specific nucleation mechanism, and stress the importance of microbes, even dead ones, on the rate of

  5. Thermal performance enhancement of erythritol/carbon foam composites via surface modification of carbon foam

    NASA Astrophysics Data System (ADS)

    Li, Junfeng; Lu, Wu; Luo, Zhengping; Zeng, Yibing

    2017-03-01

    The thermal performance of the erythritol/carbon foam composites, including thermal diffusivity, thermal capacity, thermal conductivity and latent heat, were investigated via surface modification of carbon foam using hydrogen peroxide as oxider. It was found that the surface modification enhanced the wetting ability of carbon foam surface to the liquid erythritol of the carbon foam surface and promoted the increase of erythritol content in the erythritol/carbon foam composites. The dense interfaces were formed between erythritol and carbon foam, which is due to that the formation of oxygen functional groups C=O and C-OH on the carbon surface increased the surface polarity and reduced the interface resistance of carbon foam surface to the liquid erythritol. The latent heat of the erythritol/carbon foam composites increased from 202.0 to 217.2 J/g through surface modification of carbon foam. The thermal conductivity of the erythritol/carbon foam composite before and after surface modification further increased from 40.35 to 51.05 W/(m·K). The supercooling degree of erythritol also had a large decrease from 97 to 54 °C. Additionally, the simple and effective surface modification method of carbon foam provided an extendable way to enhance the thermal performances of the composites composed of carbon foams and PCMs.

  6. 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.

  7. 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

  8. CARBON SEQUESTRATION ON SURFACE MINE LANDS

    SciTech Connect

    Donald H. Graves; Christopher Barton; Richard Sweigard; Richard Warner

    2001-01-30

    The October-December 2003 Quarter was dedicated to analyzing the first years tree planting activities and evaluation of the results. This included the analyses of the species success at each of the sites and quantifying the baseline data for future year determination of research levels of mixes. The small mammal colonization study of revegetated surface mines was also initiated and sampling systems initiated.

  9. 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.

  10. 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.

  11. Blood biocompatibility of surface-bound multi-walled carbon nanotubes.

    PubMed

    Gaffney, Alan M; Santos-Martinez, Maria J; Satti, Amro; Major, Terry C; Wynne, Kieran J; Gun'ko, Yurii K; Annich, Gail M; Elia, Giuliano; Radomski, Marek W

    2015-01-01

    Blood clots when it contacts foreign surfaces following platelet activation. This can be catastrophic in clinical settings involving extracorporeal circulation such as during heart-lung bypass where blood is circulated in polyvinyl chloride tubing. Studies have shown, however, that surface-bound carbon nanotubes may prevent platelet activation, the initiator of thrombosis. We studied the blood biocompatibility of polyvinyl chloride, surface-modified with multi-walled carbon nanotubes in vitro and in vivo. Our results show that surface-bound multi-walled carbon nanotubes cause platelet activation in vitro and devastating thrombosis in an in vivo animal model of extracorporeal circulation. The mechanism of the pro-thrombotic effect likely involves direct multi-walled carbon nanotube-platelet interaction with Ca(2+)-dependant platelet activation. These experiments provide evidence, for the first time, that modification of surfaces with nanomaterials modulates blood biocompatibility in extracorporeal circulation.

  12. Effects of CO 2 activation on porous structures of coconut shell-based activated carbons

    NASA Astrophysics Data System (ADS)

    Guo, Shenghui; Peng, Jinhui; Li, Wei; Yang, Kunbin; Zhang, Libo; Zhang, Shimin; Xia, Hongying

    2009-07-01

    In this paper, textural characterization of an activated carbon derived from carbonized coconut shell char obtained at carbonization temperature of 600 °C for 2 h by CO 2 activation was investigated. The effects of activation temperature, activation time and flow rate of CO 2 on the BET surface area, total volume, micropore volume and yield of activated carbons prepared were evaluated systematically. The results showed that: (i) enhancing activation temperature was favorable to the formation of pores, widening of pores and an increase in mesopores; (ii) increasing activation time was favorable to the formation of micropores and mesopores, and longer activation time would result in collapsing of pores; (iii) increasing flow rate of CO 2 was favorable to the reactions of all active sites and formation of pores, further increasing flow rate of CO 2 would lead carbon to burn out and was unfavorable to the formation of pores. The degree of surface roughness of activated carbon prepared was measured by the fractal dimension which was calculated by FHH (Frenkel-Halsey-Hill) theory. The fractal dimensions of activated carbons prepared were greater than 2.6, indicating the activated carbon samples prepared had very irregular structures, and agreed well with those of average micropore size.

  13. 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.

  14. Adsorption of perfluoroalkyl acids by carbonaceous adsorbents: Effect of carbon surface chemistry.

    PubMed

    Zhi, Yue; Liu, Jinxia

    2015-07-01

    Adsorption by carbonaceous sorbents is among the most feasible processes to remove perfluorooctane sulfonic (PFOS) and carboxylic acids (PFOA) from drinking and ground waters. However, carbon surface chemistry, which has long been recognized essential for dictating performance of such sorbents, has never been considered for PFOS and PFOA adsorption. Thus, the role of surface chemistry was systematically investigated using sorbents with a wide range in precursor material, pore structure, and surface chemistry. Sorbent surface chemistry overwhelmed physical properties in controlling the extent of uptake. The adsorption affinity was positively correlated carbon surface basicity, suggesting that high acid neutralizing or anion exchange capacity was critical for substantial uptake of PFOS and PFOA. Carbon polarity or hydrophobicity had insignificant impact on the extent of adsorption. Synthetic polymer-based Ambersorb and activated carbon fibers were more effective than activated carbon made of natural materials in removing PFOS and PFOA from aqueous solutions.

  15. 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.

  16. Active particles on curved surfaces

    NASA Astrophysics Data System (ADS)

    Fily, Yaouen; Baskaran, Aparna; Hagan, Michael

    Active systems have proved to be very sensitive to the geometry of their environment. This is often achieved by spending significant time at the boundary, probing its shape by gliding along it. I will discuss coarse graining the microscopic dynamics of self-propelled particles on a general curved surface to predict the way the density profile on the surface depends on its geometry. Beyond confined active particles, this formalism is a natural starting point to study objects that cannot leave the boundary at all, such as cells crawling on a curved substrate, animals running on uneven ground, or active colloids trapped at an interface.

  17. CARBON SEQUESTRATION ON SURFACE MINE LANDS

    SciTech Connect

    Donald H. Graves; Christopher Barton; Richard Sweigard; Richard Warner

    2004-08-02

    The April-June 2004 quarter was dedicated to the establishment of monitoring systems for all the new research areas. Hydrology and water quality monitoring continues to be conducted on all areas as does weather data pertinent to the research. Studies assessing specific questions pertaining to carbon flux has been established and the invasion of the vegetation by small mammals is being quantified. The approval of two experimental practices associated with this research by the United States Office of Surface Mining was a major accomplishment during this period of time. These experimental practices will eventually allow for tree planting on long steep slopes with loose grading systems and for the use of loose dumped spoil on mountain top removal areas with no grading in the final layer of rooting material for tree establishment.

  18. Adsorption of carbon monoxide on activated carbon tin ligand

    NASA Astrophysics Data System (ADS)

    Mohamad, A. B.; Iyuke, S. E.; Daud, W. R. W.; Kadhum, A. A. H.; Fisal, Z.; Al-Khatib, M. F.; Shariff, A. M.

    2000-09-01

    Activated carbon was impregnated with 34.57% SnCl 2·2H 2O salt and then dried at 180°C to produce AC-SnO 2 to improve its adsorptive interaction with CO. Besides the fact that activated carbon has its original different pore sizes for normal gas phase CO adsorption (as in the case of pure carbon), the impregnated carbon has additional CO adsorption ability due to the presence of O -(ads) on the active sites. AC-SnO 2 proved to be a superior adsorber of CO than pure carbon when used for H 2 purification in a PSA system. Discernibly, the high adsorptive selectivity of AC-SnO 2 towards gas phase CO portrays a good future for the applicability of this noble adsorbent, since CO has become a notorious threat to the global ecosystem due to the current level of air pollution.

  19. Endothelial retention and phenotype on carbonized cardiovascular implant surfaces.

    PubMed

    Frendl, Christopher M; Tucker, Scott M; Khan, Nadeem A; Esch, Mandy B; Kanduru, Shrinidhi; Cao, Thong M; García, Andrés J; King, Michael R; Butcher, Jonathan T

    2014-09-01

    Heart valve disease is an increasing clinical burden for which there is no effective treatment outside of prosthetic replacement. Over the last 20 years, clinicians have increasingly preferred the use of biological prosthetics to mechanical valves despite their superior durability because of the lifelong anticoagulation therapy that is required. Mechanical valve surface engineering has largely focused on being as non-thrombogenic as possible, but despite decades of iteration has had insufficient impact on the anticoagulation burden. In this study, we systematically evaluate the potential for endothelialization of the pyrolytic carbon surface used in mechanical valves. We compared adsorbed adhesion ligand type (collagen I, fibronectin, laminin, and purified adhesion domain fragments GFOGER and FN7-10) and concentration on endothelial adhesion rates and adhesion strength on Medtronic-Hall prosthetic valve surfaces. Regardless of ligand type or concentration, endothelial adhesion strengthening was insufficient for their intended ultra-high shear stress environment. We then hypothesized that microfabricated trenches would reduce shear stress to tolerable levels while maintaining endothelial access to the flow stream, thereby promoting a confluent and anticoagulant endothelial monolayer. Computational fluid dynamics simulations predicted an empirical relationship of channel width, depth, and spacing that would maintain interior surface shear stress within tolerable levels. Endothelial cells seeded to confluence in these channels retained a confluent monolayer when exposed to 600 dyn/cm(2) shear stress for 48 h regardless of applied adhesive ligand. Furthermore, sheared EC expressed a mature anti-coagulant profile, including endothelial nitric oxide synthase (eNOS), VE-cadherin, and significantly downregulated plasminogen activator inhibitor-1 (PAI-1). As a final test, channeled pyrolytic carbon surfaces with confluent EC reduced human platelet adhesion 1000-fold over

  20. Endothelial retention and phenotype on carbonized cardiovascular implant surfaces

    PubMed Central

    Frendl, Chris; Tucker, Scott; Khan, Nadeem; Esch, Mandy; Kanduru, Shrinidhi; Cao, Thong M.; García, Andrés J.; King, Michael R.; Butcher, Jonathan T.

    2014-01-01

    Heart valve disease is an increasing clinical burden for which there is no effective treatment outside of prosthetic replacement. Over the last 20 years, clinicians have increasingly preferred the use of biological prosthetics to mechanical valves despite their superior durability because of the lifelong anticoagulation therapy that is required. Mechanical valve surface engineering has largely focused on being as non-thrombogenic as possible, but despite decades of iteration has had insufficient impact on the anticoagulation burden. In this study, we systematically evaluate the potential for endothelialization of the pyrolytic carbon surface used in mechanical valves. We compared adsorbed adhesion ligand type (collagen I, fibronectin, laminin, and purified adhesion domain fragments GFOGER and FN7-10) and concentration on endothelial adhesion rates and adhesion strength on Medtronic-Hall prosthetic valve surfaces. Regardless of ligand type or concentration, endothelial adhesion strengthening was insufficient for their intended ultra-high shear stress environment. We then hypothesized that microfabricated trenches would reduce shear stress to tolerable levels while maintaining endothelial access to the flow stream, thereby promoting a confluent and anticoagulant endothelial monolayer. Computational fluid dynamics simulations predicted an empirical relationship of channel width, depth, and spacing that would maintain interior surface shear stress within tolerable levels. Endothelial cells seeded to confluence in these channels retained a confluent monolayer when exposed to 600 dynes/cm2 shear stress for 48 hours regardless of applied adhesive ligand. Furthermore, sheared EC expressed a mature anti-coagulant profile, including endothelial nitric oxide synthase (eNOS), VE-cadherin, and significantly downregulated plasminogen activator inhibitor-1 (PAI-1). As a final test, channeled pyrolytic carbon surfaces with confluent EC reduced human platelet adhesion 1000-fold

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

    NASA Astrophysics Data System (ADS)

    Sajad, Mehran; Kazemzad, Mahmood; Hosseinnia, Azarmidokht

    2014-04-01

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

  2. Effect of preparation method on the surface characteristics and activity of the Pd/OMS-2 catalysts for the oxidation of carbon monoxide, toluene, and ethyl acetate

    NASA Astrophysics Data System (ADS)

    Liu, Lisha; Song, Yong; Fu, Zhidan; Ye, Qing; Cheng, Shuiyuan; Kang, Tianfang; Dai, Hongxing

    2017-02-01

    The cryptomelane-type manganese oxide octahedral molecular sieve (OMS-2)-supported Pd (0.5 wt% Pd/OMS-2-DP, 0.5 wt% Pd/OMS-2-PI, and 0.5 wt% Pd/OMS-2-EX) catalysts were prepared by the deposition-precipitation, pre-incorporation, and ion-exchanging strategies, respectively. It is shown that the preparation method exerted an important effect on the physicochemical property of the sample. Among the OMS-2-supported Pd catalysts, 0.5 wt% Pd/OMS-2-DP possessed the highest surface (Mn2+ + Mn3+)/Mn4+ atomic ratio and the highest surface Pd loading and acid sites. The 0.5 wt% Pd/OMS-2 catalysts outperformed the Pd-free counterpart, among which 0.5 wt% Pd/OMS-2-DP presented the best catalytic activity (T50% and T90% were 25 and 55 °C for CO oxidation, 240 and 285 °C for toluene oxidation, and 160 and 200 °C for ethyl acetate oxidation, respectively). We believe that the high Pd surface loading, high surface atomic ratio of (Mn2+ + Mn3+)/Mn4+, and good low-temperature reducibility, good oxygen mobility, and high acidity were responsible for the excellent performance of the 0.5 wt% Pd/OMS-2-DP catalyst.

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

    PubMed

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

    2006-10-01

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

  4. Active Free Surface Density Maps

    NASA Astrophysics Data System (ADS)

    Çelen, S.

    2016-10-01

    Percolation problems were occupied to many physical problems after their establishment in 1957 by Broadbent and Hammersley. They can be used to solve complex systems such as bone remodeling. Volume fraction method was adopted to set some algorithms in the literature. However, different rate of osteoporosis could be observed for different microstructures which have the same mass density, mechanical stimuli, hormonal stimuli and nutrition. Thus it was emphasized that the bone might have identical porosity with different specific surfaces. Active free surface density of bone refers the used total area for its effective free surface. The purpose of this manuscript is to consolidate a mathematical approach which can be called as “active free surface density maps” for different surface patterns and derive their formulations. Active free surface density ratios were calculated for different Archimedean lattice models according to Helmholtz free energy and they were compared with their site and bond percolation thresholds from the background studies to derive their potential probability for bone remodeling.

  5. 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.

  6. Gold Nanoparticles Supported on Carbon Nitride: Influence of Surface Hydroxyls on Low Temperature Carbon Monoxide Oxidation

    SciTech Connect

    Singh, Joseph A; Dudney, Nancy J; Li, Meijun; Overbury, Steven {Steve} H; Veith, Gabriel M

    2012-01-01

    This paper reports the synthesis of 2.5 nm gold clusters on the oxygen free and chemically labile support carbon nitride (C3N4). Despite having small particle sizes and high enough water partial pressure these Au/C3N4 catalysts are inactive for the gas phase and liquid phase oxidation of carbon monoxide. The reason for the lack of activity is attributed to the lack of surface OH groups on the C3N4. These OH groups are argued to be responsible for the activation of CO in the oxidation of CO. The importance of basic OH groups explains the well document dependence of support isoelectric point versus catalytic activity.

  7. Evidence for Carbonate Surface Complexation during Forsterite Carbonation in Wet Supercritical Carbon Dioxide.

    PubMed

    Loring, John S; Chen, Jeffrey; Bénézeth, Pascale; Qafoku, Odeta; Ilton, Eugene S; Washton, Nancy M; Thompson, Christopher J; Martin, Paul F; McGrail, B Peter; Rosso, Kevin M; Felmy, Andrew R; Schaef, Herbert T

    2015-07-14

    Continental flood basalts are attractive formations for geologic sequestration of carbon dioxide because of their reactive divalent-cation containing silicates, such as forsterite (Mg2SiO4), suitable for long-term trapping of CO2 mineralized as metal carbonates. The goal of this study was to investigate at a molecular level the carbonation products formed during the reaction of forsterite with supercritical CO2 (scCO2) as a function of the concentration of H2O adsorbed to the forsterite surface. Experiments were performed at 50 °C and 90 bar using an in situ IR titration capability, and postreaction samples were examined by ex situ techniques, including scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), focused ion beam transmission electron microscopy (FIB-TEM), thermal gravimetric analysis mass spectrometry (TGA-MS), and magic angle spinning nuclear magnetic resonance (MAS NMR). Carbonation products and reaction extents varied greatly with adsorbed H2O. We show for the first time evidence of Mg-carbonate surface complexation under wet scCO2 conditions. Carbonate is found to be coordinated to Mg at the forsterite surface in a predominately bidentate fashion at adsorbed H2O concentrations below 27 μmol/m(2). Above this concentration and up to 76 μmol/m(2), monodentate coordinated complexes become dominant. Beyond a threshold adsorbed H2O concentration of 76 μmol/m(2), crystalline carbonates continuously precipitate as magnesite, and the particles that form are hundreds of times larger than the estimated thicknesses of the adsorbed water films of about 7 to 15 Å. At an applied level, these results suggest that mineral carbonation in scCO2 dominated fluids near the wellbore and adjacent to caprocks will be insignificant and limited to surface complexation, unless adsorbed H2O concentrations are high enough to promote crystalline carbonate formation. At a fundamental level, the surface complexes and their dependence on adsorbed H2O

  8. 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.

  9. [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.

  10. Multiwalled Carbon Nanotube Deposition on Model Environmental Surfaces

    EPA Science Inventory

    Deposition of multiwalled carbon nanotubes (MWNTs) on model environmental surfaces was investigated using a quartz crystal microbalance with dissipation monitoring (QCM-D). Deposition behaviors of MWNTs on positively and negatively charged surfaces were in good agreement with Der...

  11. CARBON SEQUESTRATION OF SURFACE MINE LANDS

    SciTech Connect

    Donald H. Graves; Christopher Barton; Richard Sweigard; Richard Warner

    2004-05-19

    The January-March 2004 Quarter was dedicated to tree planting activities in two locations in Kentucky. During year one of this project there was no available mine land to plant in the Hazard area so 107 acres were planted in the Martin county mine location. This year 120 acres was planted in the Hazard area to compensate for the prior year and an additional 57 acres was planted on Peabody properties in western Kentucky. An additional set of special plots were established on each of these areas that contained 4800 seedlings each for special carbon sequestration determinations. Plantings were also conducted to continue compaction and water quality studies on two newly established areas as well as confirmed measurements on the first years plantings. Total plantings on this project now amount to 357 acres containing 245,960 tree seedlings.

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

    SciTech Connect

    Zhang Yifu; Liu Xinghai; Nie Jiaorong; Yu Lei; Zhong Yalan; Huang Chi

    2011-02-15

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

  13. Reaction of carbon and water as catalyzed by nickel and iron surfaces

    SciTech Connect

    Kelemen, S.R.

    1986-01-01

    The individual steps of the reaction of carbon and water to produce CO and H/sub 2/ were quantified on nickel and iron surfaces using temperature-programmed reaction spectroscopy (TPRS), Auger electron spectroscopy (AES), Ultraviolet photoelectron spectroscopy (UPS) and X-ray photoelectron spectroscopy (XPS). Surface graphite and carbide, two metastable surface carbon forms, were prepared by dehydrogenation of C/sub 2/H/sub 2/ and served as reactant carbon. UPS of the graphite monolayer in contact with the metal yielded a valence electronic structure that could be interpreted in terms of the bulk band structure of graphite. The CO formation step is rate limiting in the uncatalyzed H/sub 2/O gasification reaction of graphite. The nickel surface in contact with graphitic carbon lowers the barrier for the CO formation step. The catalytic action occurs directly without isolated prior breaking of carbon-carbon bonds. The estimated activation energy for the direct reaction was 44 kcal/mole. The fully carbided surfaces of Ni and Fe were active for H/sub 2/O dissociation with an estimated activation energy between 5.0 and 10.0 kcal/mole. A different catalytic reaction cycle involving carbon-carbon bond breaking followed by oxidation of the carbide is energetically more demanding. The activation energy for direct carbon-carbon bond breaking was estimated between 65-70 kcal/mole on both nickel and iron. Following this demanding step, the reaction between carbidic carbon and oxygen proceeded on nickel and iron with estimated activation energies of 31 and 39 kcal/mole, respectively. This indirect carbide reaction cycle changed the energetics of the steam gasification of carbon.

  14. Arundo donax cane as a precursor for activated carbons preparation by phosphoric acid activation.

    PubMed

    Vernersson, T; Bonelli, P R; Cerrella, E G; Cukierman, A L

    2002-06-01

    Canes from Arundo donax, a herbaceous rapid-growing plant, were used as precursor for activated carbon preparation by phosphoric acid activation under a self-generated atmosphere. The influence of the carbonization temperature in the range 400-550 degrees C and of the weight ratio phosphoric acid to precursor (R = 1.5-2.5) on the developed porous structure of the resulting carbons was studied for 1 h of carbonization time. Surface properties of the activated carbons were dependent on a combined effect of the conditions employed. Carbons developed either with R = 1.5 over the range 400-500 degrees C, or with R = 2 at 500 degrees C exhibited surface areas of around 1100 m2/g, the latter conditions promoting a larger pore volume and enhanced mesoporous character. For both ratios, temperature above 500 degrees C led to reduction in porosity development. A similar effect was found for the highest ratio (R = 2.5) and 500 degrees C. The influence of carrying out the carbonization either for times shorter than 1 h or under flowing N2 was also examined at selected conditions (R = 2, 500 degrees C). Shorter times induced increase in the surface area (approximately 1300 m2/g), yielding carbons with smaller mean pore radius. Activated carbons obtained under flowing N2 possessed predominant microporous structures and larger ash contents than the samples derived in the self-generated atmosphere.

  15. 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

  16. 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.

  17. Removal of E. coli from water using surface-modified activated carbon filter media and its performance over an extended use.

    PubMed

    Pal, Sukdeb; Joardar, J; Song, Joon Myong

    2006-10-01

    Modification of activated carbon (AC) by aluminum hydroxychloride (AHC), and diatomaceous earth by zinc hydroxide changed the zeta potentials of these filter media from negative to positive. The modification method is amenable to room temperature, and eliminates the essential requirement of strong base treatment for making metal hydroxide coated filter media. Solid-state MAS 27Al NMR spectra suggested the presence of Al13-mer in the AHC-treated AC. AHC-modified AC samples were further treated with silver halide, and two antibacterial compounds to prevent microbial growth on filter media. In situ precipitation of silver bromide on AC resulted in formation of nanosized AgBr crystals. Bacteria removal performances of the modified media were tested in columns. For the first time, we demonstrated that only 30 g of either AHC-treated AC (60 x 200 mesh) or nano AgBr supported AC could provide >6 log E. coli removal over approximately 1000 L when the input water had a bacterial load of 10(7) CFU/mL. The filter media were robust enough to perform even when water was passed at superficial velocities 3-10 times the typical velocity (6 cm/min) of water treatment processes. Metal leaching from the modified media was found to be less than the USEPA specified Maximum Contaminant Level.

  18. 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.

  19. Surface-functionalized mesoporous carbon materials

    DOEpatents

    Dai, Sheng; Gorka, Joanna; Mayes, Richard T.

    2016-02-02

    A functionalized mesoporous carbon composition comprising a mesoporous carbon scaffold having mesopores in which polyvinyl polymer grafts are covalently attached, wherein said mesopores have a size of at least 2 nm and up to 50 nm. Also described is a method for producing the functionalized mesoporous composition, wherein a reaction medium comprising a precursor mesoporous carbon, vinyl monomer, initiator, and solvent is subjected to sonication of sufficient power to result in grafting and polymerization of the vinyl monomer into mesopores of the precursor mesoporous carbon. Also described are methods for using the functionalized mesoporous carbon, particularly in extracting metal ions from metal-containing solutions.

  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.

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

    PubMed

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

    2016-11-24

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

  2. [Raman spectra of PAN-based carbon fibers during surface treatment].

    PubMed

    Cao, Wei-wei; Zhu, Bo; Jing, Min; Wang, Cheng-guo

    2008-12-01

    Laser Raman spectroscopy was employed to characterize the microstructure changes of PAN based carbon fibers among different surface treatments, and the characteristics of first-order Raman spectra of carbon fibers during surface treatment were investigated in the present paper. The results show that the variety of carbon fibers' phase structures can be represented by Raman spectroscopy parameters, such as the Raman frequency shifts of main D and G bands, FWHMs and additive bands' area ratios at the positions of different Raman frequency shifts. During different surface treatment, some changes in the first-order Raman spectroscopy parameters of PAN based carbon fibers were observed, the Raman frequency shifts of D and G bands moved toward higher wavenumber, and the values of R(I(D)/I(G)) also improved, which can be used to measure the graphite crystallite size of carbon fiber. It is suggested that the graphite microstructure of carbon fibers is decomposed during surface treatment, the crystallite size is reduced, and the activity of the graphite crystallite boundary is improved. Moreover, the full-widths at half maximum (FWHM) of D and G bands both decrease, which can give information on the order of graphite microstructure and the quantity of defects in carbon fibers, and the relative bands' areas of A and D" bands also decrease, which can be attributed to the structure of amorphous carbon or some kinds of organic functional groups in carbon fibers. These differences among the spectra demonstrate that the structure of amorphous carbon in carbon fibers is easier to oxidize or decompose than multilayer graphite structure, so the relative proportion of amorphous carbon decreases during surface treatment. The conclusions obtained by Raman spectra are basically in agreement with the improvement of apparent crystallization degrees of carbon fibers during surface treatment, which were calculated by X-ray diffraction method. So the variety rules of carbon fibers' phase

  3. Carbon Sequestration on Surface Mine Lands

    SciTech Connect

    Donald Graves; Christopher Barton; Richard Sweigard; Richard Warner; Carmen Agouridis

    2006-03-31

    Since the implementation of the federal Surface Mining Control and Reclamation Act of 1977 (SMCRA) in May of 1978, many opportunities have been lost for the reforestation of surface mines in the eastern United States. Research has shown that excessive compaction of spoil material in the backfilling and grading process is the biggest impediment to the establishment of productive forests as a post-mining land use (Ashby, 1998, Burger et al., 1994, Graves et al., 2000). Stability of mine sites was a prominent concern among regulators and mine operators in the years immediately following the implementation of SMCRA. These concerns resulted in the highly compacted, flatly graded, and consequently unproductive spoils of the early post-SMCRA era. However, there is nothing in the regulations that requires mine sites to be overly compacted as long as stability is achieved. It has been cultural barriers and not regulatory barriers that have contributed to the failure of reforestation efforts under the federal law over the past 27 years. Efforts to change the perception that the federal law and regulations impede effective reforestation techniques and interfere with bond release must be implemented. Demonstration of techniques that lead to the successful reforestation of surface mines is one such method that can be used to change perceptions and protect the forest ecosystems that were indigenous to these areas prior to mining. The University of Kentucky initiated a large-scale reforestation effort to address regulatory and cultural impediments to forest reclamation in 2003. During the three years of this project 383,000 trees were planted on over 556 acres in different physiographic areas of Kentucky (Table 1, Figure 1). Species used for the project were similar to those that existed on the sites before mining was initiated (Table 2). A monitoring program was undertaken to evaluate growth and survival of the planted species as a function of spoil characteristics and

  4. 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.

  5. 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.

  6. Iron oxide nanoparticles embedded in activated carbons prepared from hydrothermally treated waste biomass.

    PubMed

    Hao, Wenming; Björkman, Eva; Yun, Yifeng; Lilliestråle, Malte; Hedin, Niklas

    2014-03-01

    Particles of iron oxide (Fe3O4 ; 20–40 nm) were embedded within activated carbons during the activation of hydrothermally carbonized (HTC) biomasses in a flow of CO2. Four different HTC biomass samples (horse manure, grass cuttings, beer production waste, and biosludge) were used as precursors for the activated carbons. Nanoparticles of iron oxide formed from iron catalyst included in the HTC biomasses. After systematic optimization, the activated carbons had specific surface areas of about 800 m2g1. The pore size distributions of the activated carbons depended strongly on the degree of carbonization of the precursors. Activated carbons prepared from highly carbonized precursors had mainly micropores, whereas those prepared from less carbonized precursors contained mainly mesopores. Given the strong magnetism of the activated carbon–nano-Fe3O4 composites, they could be particularly useful for water purification.

  7. CARBON SEQUESTRATION ON SURFACE MINE LANDS

    SciTech Connect

    Donald H. Graves; Christopher Barton; Richard Sweigard; Richard Warner

    2005-02-25

    The October-December Quarter was dedicated to analyzing the first two years tree planting activities and evaluation of the results. This included the analyses of the species success at each of the sites and quantifying the data for future year determination of research levels. Additional detailed studies have been planned to further quantify total carbon storage accumulation on the research areas. At least 124 acres of new plantings will be established in 2005 to bring the total to 500 acres or more in the study area across the state of Kentucky. During the first 2 years of activities, 172,000 tree seedlings were planted on 257 acres in eastern Kentucky and 77,520 seedlings were planted on 119 acres in western Kentucky. The quantities of each species was discussed in the first Annual Report. A monitoring program was implemented to measure treatment effects on above and below ground C and nitrogen (N) pools and fluxes. A sampling strategy was devised that will allow for statistical comparisons of the various species within planting conditions and sites. Seedling heights and diameters are measured for initial status and re-measured on an annual basis. Leaves were harvested and leaf area measurements were performed. They were then dried and weighed and analyzed for C and N. Whole trees were removed to determine biomass levels and to evaluate C and N levels in all components of the trees. Clip plots were taken to determine herbaceous production and litter was collected in baskets and gathered each month to quantify C & N levels. Soil samples were collected to determine the chemical and mineralogical characterization of each area. The physical attributes of the soils are also being determined to provide information on the relative level of compaction. Hydrology and water quality monitoring is being conducted on all areas. Weather data is also being recorded that measures precipitation values, temperature, relative humidity wind speed and direction and solar radiation

  8. Active and responsive polymer surfaces.

    PubMed

    Zhang, Jilin; Han, Yanchun

    2010-02-01

    A central challenge in polymer science today is creating materials that dynamically alter their structures and properties on demand, or in response to changes in their environment. Surfaces represent an attractive area of focus, since they exert disproportionately large effects on properties such as wettability, adhesiveness, optical appearance, and bioactivity, enabling pronounced changes in properties to be accomplished through subtle changes in interfacial structure or chemistry. In this critical review, we review the recent research progress into active and responsive polymer surfaces. The chief purpose of this article is to summarize the advanced preparation techniques and applications in this field from the past decade. This review should be of interest both to new scientists in this field and the interdisciplinary researchers who are working on "intelligent" polymer surfaces (117 references).

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

    PubMed

    Qiu, Guannan; Guo, Mingxin

    2010-01-01

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

  10. Electroadsorption of Arsenic from natural water in granular activated carbon

    NASA Astrophysics Data System (ADS)

    Beralus, Jean-Mackson; Ruiz Rosas, Ramiro; Cazorla-Amoros, Diego; Morallon, Emilia

    2014-11-01

    The adsorption and electroadsorption of arsenic from a natural water has been studied in a filter-press electrochemical cell using a commercial granular activated carbon as adsorbent and Pt/Ti and graphite as electrodes. A significant reduction of the arsenic concentration is achieved when current is imposed between the electrodes, especially when the activated carbon was located in the vicinity of the anode. This enhancement can be explained in terms of the presence of electrostatic interactions between the polarized carbon surface and the arsenic ions, and changes in the distribution of most stable species of arsenic in solution due to As(III) to As(V) oxidation. In summary, electrochemical adsorption on a filter press cell can be used for enhancement the arsenic remediation with activated carbon in the treatment of a real groundwater.

  11. 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.

  12. 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.

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

    NASA Technical Reports Server (NTRS)

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

    1996-01-01

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

  14. 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

  15. 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

  16. Adsorption Properties of Lignin-derived Activated Carbon Fibers (LACF)

    SciTech Connect

    Contescu, Cristian I.; Gallego, Nidia C.; Thibaud-Erkey, Catherine; Karra, Reddy

    2016-04-01

    The object of this CRADA project between Oak Ridge National Laboratory (ORNL) and United Technologies Research Center (UTRC) is the characterization of lignin-derived activated carbon fibers (LACF) and determination of their adsorption properties for volatile organic compounds (VOC). Carbon fibers from lignin raw materials were manufactured at Oak Ridge National Laboratory (ORNL) using the technology previously developed at ORNL. These fibers were physically activated at ORNL using various activation conditions, and their surface area and pore-size distribution were characterized by gas adsorption. Based on these properties, ORNL did down-select five differently activated LACF materials that were delivered to UTRC for measurement of VOC adsorption properties. UTRC used standard techniques based on breakthrough curves to measure and determine the adsorption properties of indoor air pollutants (IAP) - namely formaldehyde and carbon dioxide - and to verify the extent of saturated fiber regenerability by thermal treatments. The results are summarized as follows: (1) ORNL demonstrated that physical activation of lignin-derived carbon fibers can be tailored to obtain LACF with surface areas and pore size distributions matching the properties of activated carbon fibers obtained from more expensive, fossil-fuel precursors; (2) UTRC investigated the LACF potential for use in air cleaning applications currently pursued by UTRC, such as building ventilation, and demonstrated their regenerability for CO2 and formaldehyde, (3) Both partners agree that LACF have potential for possible use in air cleaning applications.

  17. Surface Modification of a Nanoporous Carbon Photoanode upon Irradiation.

    PubMed

    Gomis-Berenguer, Alicia; Velo-Gala, Inmaculada; Rodríguez-Castellón, Enrique; Ania, Conchi O

    2016-11-23

    The photocorrosion of a nanoporous carbon photoanode, with low surface functionalization and high performance towards the photoelectrochemical oxidation of water using simulated solar light, was investigated. Two different light configurations were used to isolate the effect of the irradiation wavelength (UV and visible light) on the textural and chemical features of the carbon photoanode, and its long-term photocatalytic performance for the oxygen evolution reaction. A complete characterization of the carbon showed that the photocorrosion of carbon anodes of low functionalization follows a different pathway than highly functionalized carbons. The carbon matrix gets slightly oxidized, with the formation of carboxylic and carbonyl-like moieties in the surface of the carbon anode after light exposure. The oxidation of the carbon occurred due to the photogeneration of oxygen reactive species upon the decomposition of water during the irradiation of the photoanodes. Furthermore, the photoinduced surface reactions depend on the nature of the carbon anode and its ability to photogenerate reactive species in solution, rather than on the wavelength of the irradiation source. This surface modification is responsible for the decreased efficiency of the carbon photoanode throughout long illumination periods, due to the effect of the oxidation of the carbon matrix on the charge transfer. In this work, we have corroborated that, in the case of a low functionalization carbon material, the photocorrosion also occurs although it proceeds through a different pathway. The carbon anode gets gradually slightly oxidized due to the photogeneration of O-reactive species, being the incorporation of the O-groups responsible for the decreased performance of the anode upon long-term irradiation due to the effect of the oxidation of the carbon matrix on the electron transfer.

  18. Solvent recovery improved with activated carbon fibers

    SciTech Connect

    Not Available

    1982-11-01

    A non-woven net of activated carbon fibers as absorbing media, representing a major advancement in vapor recovery technology, is presented. The carbon fiber exhibits mass transfer coefficients for adsorption description of up to 100 times that of conventional systems.

  19. Heterogeneity of activated carbons in adsorption of aniline from aqueous solutions

    NASA Astrophysics Data System (ADS)

    Podkościelny, P.; László, K.

    2007-08-01

    The heterogeneity of activated carbons (ACs) prepared from different precursors is investigated on the basis of adsorption isotherms of aniline from dilute aqueous solutions at various pH values. The APET carbon prepared from polyethyleneterephthalate (PET), as well as, commercial ACP carbon prepared from peat were used. Besides, to investigate the influence of carbon surface chemistry, the adsorption was studied on modified carbons based on ACP carbon. Its various oxygen surface groups were changed by both nitric acid and thermal treatments. The Dubinin-Astakhov (DA) equation and Langmuir-Freundlich (LF) one have been used to model the phenomenon of aniline adsorption from aqueous solutions on heterogeneous carbon surfaces. Adsorption-energy distribution (AED) functions have been calculated by using an algorithm based on a regularization method. Analysis of these functions for activated carbons studied provides important comparative information about their surface heterogeneity.

  20. Carbon-based supercapacitors produced by activation of graphene.

    PubMed

    Zhu, Yanwu; Murali, Shanthi; Stoller, Meryl D; Ganesh, K J; Cai, Weiwei; Ferreira, Paulo J; Pirkle, Adam; Wallace, Robert M; Cychosz, Katie A; Thommes, Matthias; Su, Dong; Stach, Eric A; Ruoff, Rodney 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(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.

  1. 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.

  2. 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.

  3. 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.

  4. Activated Carbon Textile via Chemistry of Metal Extraction for Supercapacitors.

    PubMed

    Lam, Do Van; Jo, Kyungmin; Kim, Chang-Hyun; Kim, Jae-Hyun; Lee, Hak-Joo; Lee, Seung-Mo

    2016-12-27

    Carbothermic reduction in the chemistry of metal extraction (MO(s) + C(s) → M(s) + CO(g)) using carbon as a sacrificial agent has been used to smelt metals from diverse oxide ores since ancient times. Here, we paid attention to another aspect of the carbothermic reduction to prepare an activated carbon textile for high-rate-performance supercapacitors. On the basis of thermodynamic reducibility of metal oxides reported by Ellingham, we employed not carbon, but metal oxide as a sacrificial agent in order to prepare an activated carbon textile. We conformally coated ZnO on a bare cotton textile using atomic layer deposition, followed by pyrolysis at high temperature (C(s) + ZnO(s) → C'(s) + Zn(g) + CO(g)). We figured out that it leads to concurrent carbonization and activation in a chemical as well as mechanical way. Particularly, the combined effects of mechanical buckling and fracture that occurred between ZnO and cotton turned out to play an important role in carbonizing and activating the cotton textile, thereby significantly increasing surface area (nearly 10 times) compared with the cotton textile prepared without ZnO. The carbon textiles prepared by carbothermic reduction showed impressive combination properties of high power and energy densities (over 20-fold increase) together with high cyclic stability.

  5. Collector surface for a microwave tube comprising a carbon-bonded carbon-fiber composite

    DOEpatents

    Lauf, R.J.; McMillan, A.D.; Johnson, A.C.; Moorhead, A.J.

    1998-07-28

    In a microwave tube, an improved collector surface coating comprises a porous carbon composite material, preferably a carbon-bonded carbon fiber composite having a bulk density less than about 2 g/cc. Installation of the coating is readily adaptable as part of the tube manufacturing process. 4 figs.

  6. Collector surface for a microwave tube comprising a carbon-bonded carbon-fiber composite

    DOEpatents

    Lauf, Robert J.; McMillan, April D.; Johnson, Arvid C.; Moorhead, Arthur J.

    1998-01-01

    In a microwave tube, an improved collector surface coating comprises a porous carbon composite material, preferably a carbon-bonded carbon fiber composite having a bulk density less than about 2 g/cc. Installation of the coating is readily adaptable as part of the tube manufacturing process.

  7. Monitoring by Control Technique - Activated Carbon Adsorber

    EPA Pesticide Factsheets

    Stationary source emissions monitoring is required to demonstrate that a source is meeting the requirements in Federal or state rules. This page is about Activated Carbon Adsorber control techniques used to reduce pollutant emissions.

  8. Activated carbon from char obtained from vacuum pyrolysis of teak sawdust: pore structure development and characterization.

    PubMed

    Ismadji, S; Sudaryanto, Y; Hartono, S B; Setiawan, L E K; Ayucitra, A

    2005-08-01

    The preparation of activated carbon from vacuum pyrolysis char of teak sawdust was studied and the results are presented in this paper. The effects of process variables such as temperature and activation time on the pore structure of activated carbons were studied. The activated carbon prepared from char obtained by vacuum pyrolysis has higher surface area and pore volume than that from atmospheric pyrolysis char. The BET surface area and pore volume of activated carbon prepared from vacuum pyrolysis char were 1150 m2/g and 0.43 cm3/g, respectively.

  9. Physicochemical effect of activation temperature on the sorption properties of pine shell activated carbon.

    PubMed

    Wasim, Agha Arslan; Khan, Muhammad Nasiruddin

    2017-03-01

    Activated carbons produced from a variety of raw materials are normally selective towards a narrow range of pollutants present in wastewater. This study focuses on shifting the selectivity of activated carbon from inorganic to organic pollutants using activation temperature as a variable. The material produced from carbonization of pine shells substrate was activated at 250°C and 850°C. Both adsorbents were compared with commercial activated carbon for the sorption of lead, cadmium, methylene blue, methyl blue, xylenol orange, and crystal violet. It was observed that carbon activated at 250°C was selective for lead and cadmium whereas the one activated at 850°C was selective for the organic dyes. The Fourier transform infrared spectroscopy study revealed that AC850 had less surface functional groups as compared to AC250. Point of zero charge and point of zero salt effect showed that AC250 had acidic groups at its surface. Scanning electron microscopy depicted that increase in activation temperature resulted in an increase in pore size of activated carbon. Both AC250 and AC850 followed pseudo-second-order kinetics. Temkin isotherm model was a best fit for empirical data obtained at equilibrium. The model also showed that sorption process for both AC250 and AC850 was physisorption.

  10. Dye removal of activated carbons prepared from NaOH-pretreated rice husks by low-temperature solution-processed carbonization and H3PO4 activation.

    PubMed

    Chen, Yun; Zhai, Shang-Ru; Liu, Na; Song, Yu; An, Qing-Da; Song, Xiao-Wei

    2013-09-01

    A coupling of low-temperature sulfuric acid-assisted carbonization and H3PO4 activation was employed to convert NaOH-pretreated rice husks into activated carbons with extremely high surface area (2028 m(2) g(-1)) and integrated characteristics. The influences of the activation temperature and impregnation ratio on the surface area, pore volume of activated carbons were thoroughly investigated. The morphology and surface chemistry of activated carbons were characterized using N2 sorption, FTIR, XPS, SEM, TEM, etc. The adsorption capacity of resulting carbons obtained under optimum preparation conditions was systematically evaluated using methylene blue under various simulated conditions. The adsorption process can be well described by both Langmuir isotherm model and the pseudo-second order kinetics models; and the maximum monolayer capacity of methylene blue was ca. 578 mg g(-1).

  11. Bimodal activated carbons derived from resorcinol-formaldehyde cryogels

    PubMed Central

    Szczurek, Andrzej; Amaral-Labat, Gisele; Fierro, Vanessa; Pizzi, Antonio; Celzard, Alain

    2011-01-01

    Resorcinol-formaldehyde cryogels prepared at different dilution ratios have been activated with phosphoric acid at 450 °C and compared with their carbonaceous counterparts obtained by pyrolysis at 900 °C. Whereas the latter were, as expected, highly mesoporous carbons, the former cryogels had very different pore textures. Highly diluted cryogels allowed preparation of microporous materials with high surface areas, but activation of initially dense cryogels led to almost non-porous carbons, with much lower surface areas than those obtained by pyrolysis. The optimal acid concentration for activation, corresponding to stoichiometry between molecules of acid and hydroxyl groups, was 2 M l−1, and the acid–cryogel contact time also had an optimal value. Such optimization allowed us to achieve surface areas and micropore volumes among the highest ever obtained by activation with H3PO4, close to 2200 m2 g−1 and 0.7 cm3 g−1, respectively. Activation of diluted cryogels with a lower acid concentration of 1.2 M l−1 led to authentic bimodal activated carbons, having a surface area as high as 1780 m2 g−1 and 0.6 cm3 g−1 of microporous volume easily accessible through a widely developed macroporosity. PMID:27877405

  12. 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

    2016-10-05

    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.

  13. Oxidation of activated carbon: application to vinegar decolorization.

    PubMed

    López, Francisco; Medina, Francisco; Prodanov, Marin; Güell, Carme

    2003-01-15

    This article reports studies on the feasibility of increasing the decoloring capacity of a granular activated carbon (GAC) by using oxidation with air at 350 degrees C to modify its surface activity and porosity. The GAC, obtained from olive stones, had a maximum decolorization capacity of 92% for doses of 20 g/l, while the maximum decolorization capacity of the modified granular activated carbon (MGAC) was about 96% at a dose of 10 g/l. The increase in decoloring capacity is thought to be due to an increase in mesopore area (from 129 to 340 m2/g) in the MGAC. The maximum decoloring values and the doses needed to attain them are very close to values obtained in previous studies using coconut shell powder-activated carbon (94 and 98% for red and white vinegar for a dose of 10 g/l, respectively).

  14. Surface Chemistry and Water Dispersability of Carbon Black Materials

    SciTech Connect

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

    2006-01-01

    Formulation of water-stable carbon black dispersions is a double-sided task, which requires selection of a proper dispersing agents and matching it with the properties of a specific carbon black. Among other properties that affect water dispersability of carbon blacks (particle size, surface area, and aggregate structure), surface chemistry plays a prime-order role. We have characterized physical and chemical properties of several carbon black materials, and correlated them with the stability of dispersions formed with ionic and non-ionic surfactants. In particular, chemical characterization of surface functional groups on carbon blacks based on potentiometric titration measurements (pKa spectra) provided a comprehensive picture of pH effects on dispersion stability. The results obtained were complemented by information from physical characterization methods, such as XPS and FTIR. The selection of a suitable dispersing agent able to withstand large pH variations will be discussed.

  15. 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.

  16. 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.

  17. 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

  18. Synthesis of High-Surface-Area Nitrogen-Doped Porous Carbon Microflowers and Their Efficient Carbon Dioxide Capture Performance.

    PubMed

    Li, Yao; Cao, Minhua

    2015-07-01

    Sustainable carbon materials have received particular attention in CO2 capture and storage owing to their abundant pore structures and controllable pore parameters. Here, we report high-surface-area hierarchically porous N-doped carbon microflowers, which were assembled from porous nanosheets by a three-step route: soft-template-assisted self-assembly, thermal decomposition, and KOH activation. The hydrazine hydrate used in our experiment serves as not only a nitrogen source, but also a structure-directing agent. The activation process was carried out under low (KOH/carbon=2), mild (KOH/carbon=4) and severe (KOH/carbon=6) activation conditions. The mild activated N-doped carbon microflowers (A-NCF-4) have a hierarchically porous structure, high specific surface area (2309 m(2)  g(-1)), desirable micropore size below 1 nm, and importantly large micropore volume (0.95 cm(3)  g(-1)). The remarkably high CO2 adsorption capacities of 6.52 and 19.32 mmol g(-1) were achieved with this sample at 0 °C (273 K) and two pressures, 1 bar and 20 bar, respectively. Furthermore, this sample also exhibits excellent stability during cyclic operations and good separation selectivity for CO2 over N2.

  19. Enhanced mercuric chloride adsorption onto sulfur-modified activated carbons derived from waste tires.

    PubMed

    Yuan, Chung-Shin; Wang, Guangzhi; Xue, Sheng-Han; Ie, Iau-Ren; Jen, Yi-Hsiu; Tsai, Hsieh-Hung; Chen, Wei-Jin

    2012-07-01

    A number of activated carbons derived from waste tires were further impregnated by gaseous elemental sulfur at temperatures of 400 and 650 degrees C, with a carbon and sulfur mass ratio of 1:3. The capabilities of sulfur diffusing into the micropores of the activated carbons were significantly different between 400 and 650 degrees C, resulting in obvious dissimilarities in the sulfur content of the activated carbons. The sulfur-impregnated activated carbons were examined for the adsorptive capacity of gas-phase mercuric chloride (HgC1) by thermogravimetric analysis (TGA). The analytical precision of TGA was up to 10(-6) g at the inlet HgCl2 concentrations of 100, 300, and 500 microg/m3, for an adsorption time of 3 hr and an adsorption temperature of 150 degrees C, simulating the flue gas emitted from municipal solid waste (MSW) incinerators. Experimental results showed that sulfur modification can slightly reduce the specific surface area of activated carbons. High-surface-area activated carbons after sulfur modification had abundant mesopores and micropores, whereas low-surface-area activated carbons had abundant macropores and mesopores. Sulfur molecules were evenly distributed on the surface of the inner pores after sulfur modification, and the sulfur content of the activated carbons increased from 2-2.5% to 5-11%. After sulfur modification, the adsorptive capacity of HgCl2 for high-surface-area sulfurized activated carbons reached 1.557 mg/g (22 times higher than the virgin activated carbons). The injection of activated carbons was followed by fabric filtration, which is commonly used to remove HgCl2 from MSW incinerators. The residence time of activated carbons collected in the fabric filter is commonly about 1 hr, but the time required to achieve equilibrium is less than 10 min. Consequently, it is worthwhile to compare the adsorption rates of HgCl2 in the time intervals of < 10 and 10-60 min.

  20. Investigating effectiveness of activated carbons of natural sources on various supercapacitors

    NASA Astrophysics Data System (ADS)

    Faisal, Md. Shahnewaz Sabit; Rahman, Muhammad M.; Asmatulu, Ramazan

    2016-04-01

    Activated carbon can be produced from natural sources, such as pistachio and acorn shells, which can be an inexpensive and sustainable sources of natural wastes for the energy storage devices, such as supercapacitors. The carbonaceous materials used in this study were carbonized at the temperatures of 700°C and 900°C after the stabilization process at 240°C for two hours. These shells showed approximately 60% carbon yield. Carbonized nutshells were chemically activated using1wt% potassium hydroxide (KOH). Activated carbon powders with polyvinylidene fluoride (PVdF) were used to construct carbon electrodes. A 1M of tetraethylammonium tetrafluoroborate (TEABF4) and propylene carbonate (PC) were used as electrolytes. Electrochemical techniques, such as cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used for the characterization of the supercapacitors. Scanning electron microscopy (SEM) was used to inspect the surface texture of the activated carbons. Activated pistachio shells carbonized at 700°C showed more porous surface texture than those carbonized at 900°C. Effects of the carbonization temperatures were studied for their electrochemical characteristics. The shells carbonized at 700°C showed better electrochemical characteristics compared to those carbonized at 900°C. The test results provided about 27,083 μF/g specific capacitance at a scan rate of 10mV/s. This study showed promising results for using these activated carbons produced from the natural wastes for supercapacitor applications.

  1. Autonomous Experimentation of Carbon Nanotube Using Response Surface Methods

    DTIC Science & Technology

    2015-03-26

    copyright protection in the United States. AFIT-ENS-MS-15-M-113 AUTOMONOUS EXPERIMENTATION OF CARBON NANOTUBE GROWTH USING RESPONSE SURFACE...UNLIMITED. AFIT-ENS-MS-15-M-113 AUTOMONOUS EXPERIMENTATION OF CARBON NANOTUBE GROWTH USING RESPONSE SURFACE METHODS William Adorno III, BS...discussed as an emerging technology for many applications, but AFRL has yet to discover what factors optimize the nanotube initial growth rate. In this

  2. Carbon dioxide in the ocean surface: The homogeneous buffer factor

    USGS Publications Warehouse

    Sundquist, E.T.; Plummer, L.N.; Wigley, T.M.L.

    1979-01-01

    The amount of carbon dioxide that can be dissolved in surface seawater depends at least partially on the homogeneous buffer factor, which is a mathematical function of the chemical equilibrium conditions among the various dissolved inorganic species. Because these equilibria are well known, the homogeneous buffer factor is well known. Natural spatial variations depend very systematically on sea surface temperatures, and do not contribute significantly to uncertainties in the present or future carbon dioxide budget. Copyright ?? 1979 AAAS.

  3. Activated carbon derived from carbon residue from biomass gasification and its application for dye adsorption: Kinetics, isotherms and thermodynamic studies.

    PubMed

    Maneerung, Thawatchai; Liew, Johan; Dai, Yanjun; Kawi, Sibudjing; Chong, Clive; Wang, Chi-Hwa

    2016-01-01

    In this work, activated carbon (AC) as an effective and low-cost adsorbent was successfully prepared from carbon residue (or char, one of the by-products from woody biomass gasification) via physical activation. The surface area of char was significantly increased from 172.24 to 776.46m(2)/g after steam activation at 900°C. The obtained activated carbons were then employed for the adsorption of dye (Rhodamine B) and it was found that activated carbon obtained from steam activation exhibited the highest adsorption capability, which is mainly attributed to the higher surface area and the abundance of hydroxyl (-OH) and carboxyl (-COOH) groups on the activated carbon surface. Moreover, it was also found that the adsorption capability significantly increased under the basic condition, which can be attributed to the increased electrostatic interaction between the deprotonated (negatively charged) activated carbon and dye molecules. Furthermore, the equilibrium data were fitted into different adsorption isotherms and found to fit well with Langmuir model (indicating that dye molecules form monolayer coverage on activated carbon) with a maximum monolayer adsorption capability of 189.83mg/g, whereas the adsorption kinetics followed the pseudo-second-order kinetics.

  4. Studies on Supercapacitor Electrode Material from Activated Lignin-Derived Mesoporous Carbon

    SciTech Connect

    Saha, Dipendu; Li, Yunchao; Bi, Zhonghe; Chen, Jihua; Keum, Jong Kahk; Hensley, Dale K; Grappe, Hippolyte A.; Meyer III, Harry M; Dai, Sheng; Paranthaman, Mariappan Parans; Naskar, Amit K

    2014-01-01

    We synthesized mesoporous carbon from pre-cross-linked lignin gel impregnated with a surfactant as the pore-forming agent, and then activated the carbon through physical and chemical methods to obtain activated mesoporous carbon. The activated mesoporous carbons exhibited 1.5- to 6-fold increases in porosity with a maximum BET specific surface area of 1148 m2/g and a pore volume of 1.0 cm3/g. Slow physical activation helped retain dominant mesoporosity; however, aggressive chemical activation caused some loss of the mesopore volume fraction. Plots of cyclic voltammetric data with the capacitor electrode made from these carbons showed an almost rectangular curve depicting the behavior of ideal double-layer capacitance. Although the pristine mesoporous carbon exhibited the same range of surface-area-based capacitance as that of other known carbon-based supercapacitors, activation decreased the surface-area-based specific capacitance and increased the gravimetric-specific capacitance of the mesoporous carbons. Surface activation lowered bulk density and electrical conductivity. Warburg impedance as a vertical tail in the lower frequency domain of Nyquist plots supported good supercapacitor behavior for the activated mesoporous carbons. Our work demonstrated that biomass-derived mesoporous carbon materials continue to show potential for use in specific electrochemical applications.

  5. Mesoporous carbons with self-assembled surfaces of defined crystal orientation.

    PubMed

    Jian, Kengqing; Truong, Trung C; Hoffman, Wesley P; Hurt, Robert H

    2008-02-01

    The design of carbon sorbents traditionally focuses on the control of pore structure and the number and type of surface functional groups. The present paper explores the potential of also controlling the carbon crystal structure, or graphene layer orientation, in the immediate vicinity of the internal surfaces. We hypothesize that this crystal structure influences the properties of the carbon surfaces and affects the number and type of active sites for functionalization. Here a series of mesoporous carbons are fabricated by capillary infiltration of mesophase pitch (naphthalene homopolymer) into a series of controlled pore glass templates of different characteristic pore size followed by carbonization and template etching. The liquid crystalline mesogens are known to adopt perpendicular alignment (anchoring) at liquid/silica interfaces, which after carbonization lead to a high concentration of graphene edge sites at the inner surfaces. These surfaces are shown to have elevated chemical reactivity, and the pore structures are shown to be consistent with predictions of a quantitative model based on the negative replica concept. Overall, the use of mesophase pitch for templated mesoporous carbons allows systematic and simultaneous control of both pore structure and interfacial crystal structure through the well-defined rules of liquid crystal surface anchoring.

  6. Mesoporous carbons with self-assembled surfaces of defined crystal orientation

    PubMed Central

    Jian, Kengqing; Truong, Trung C.; Hoffman, Wesley P.; Hurt, Robert H.

    2008-01-01

    The design of carbon sorbents traditionally focuses on the control of pore structure and the number and type of surface functional groups. The present paper explores the potential of also controlling the carbon crystal structure, or graphene layer orientation, in the immediate vicinity of the internal surfaces. We hypothesize that this crystal structure influences the properties of the carbon surfaces and affects the number and type of active sites for functionalization. Here a series of mesoporous carbons are fabricated by capillary infiltration of mesophase pitch (naphthalene homopolymer) into a series of controlled pore glass templates of different characteristic pore size followed by carbonization and template etching. The liquid crystalline mesogens are known to adopt perpendicular alignment (anchoring) at liquid/silica interfaces, which after carbonization lead to a high concentration of graphene edge sites at the inner surfaces. These surfaces are shown to have elevated chemical reactivity, and the pore structures are shown to be consistent with predictions of a quantitative model based on the negative replica concept. Overall, the use of mesophase pitch for templated mesoporous carbons allows systematic and simultaneous control of both pore structure and interfacial crystal structure through the well-defined rules of liquid crystal surface anchoring. PMID:19190761

  7. Magnetite impregnation effects on the sorbent properties of activated carbons and biochars.

    PubMed

    Han, Zhantao; Sani, Badruddeen; Mrozik, Wojciech; Obst, Martin; Beckingham, Barbara; Karapanagioti, Hrissi K; Werner, David

    2015-03-01

    This paper discusses the sorbent properties of magnetic activated carbons and biochars produced by wet impregnation with iron oxides. The sorbents had magnetic susceptibilities consistent with theoretical predictions for carbon-magnetite composites. The high BET surface areas of the activated carbons were preserved in the synthesis, and enhanced for one low surface area biochar by dissolving carbonates. Magnetization decreased the point of zero charge. Organic compound sorption correlated strongly with BET surface areas for the pristine and magnetized materials, while metal cation sorption did not show such a correlation. Strong sorption of the hydrophobic organic contaminant phenanthrene to the activated carbon or biochar surfaces was maintained following magnetite impregnation, while phenol sorption was diminished, probably due to enhanced carbon oxidation. Copper, zinc and lead sorption to the activated carbons and biochars was unchanged or slightly enhanced by the magnetization, and iron oxides also contributed to the composite metal sorption capacity. While a magnetic biochar with 219 ± 3.7 m(2)/g surface area nearly reached the very strong organic pollutant binding capacity of the two magnetic activated carbons, a magnetic biochar with 68 ± 2.8 m(2)/g surface area was the best metal sorbent. Magnetic biochars thus hold promise as more sustainable alternatives to coal-derived magnetic activated carbons.

  8. Surface characterization of LDEF carbon fiber/polymer matrix composites

    NASA Technical Reports Server (NTRS)

    Grammer, Holly L.; Wightman, James P.; Young, Philip R.; Slemp, Wayne S.

    1995-01-01

    XPS (x-ray photoelectron spectroscopy) and SEM (scanning electron microscopy) analysis of both carbon fiber/epoxy matrix and carbon fiber/polysulfone matrix composites revealed significant changes in the surface composition as a result of exposure to low-earth orbit. The carbon 1s curve fit XPS analysis in conjunction with the SEM photomicrographs revealed significant erosion of the polymer matrix resins by atomic oxygen to expose the carbon fibers of the composite samples. This erosion effect on the composites was seen after 10 months in orbit and was even more obvious after 69 months.

  9. Hydrogen adsorption on functionalized nanoporous activated carbons.

    PubMed

    Zhao, X B; Xiao, B; Fletcher, A J; Thomas, K M

    2005-05-12

    There is considerable interest in hydrogen adsorption on carbon nanotubes and porous carbons as a method of storage for transport and related energy applications. This investigation has involved a systematic investigation of the role of functional groups and porous structure characteristics in determining the hydrogen adsorption characteristics of porous carbons. Suites of carbons were prepared with a wide range of nitrogen and oxygen contents and types of functional groups to investigate their effect on hydrogen adsorption. The porous structures of the carbons were characterized by nitrogen (77 K) and carbon dioxide (273 K) adsorption methods. Hydrogen adsorption isotherms were studied at 77 K and pressure up to 100 kPa. All the isotherms were Type I in the IUPAC classification scheme. Hydrogen isobars indicated that the adsorption of hydrogen is very temperature dependent with little or no hydrogen adsorption above 195 K. The isosteric enthalpies of adsorption at zero surface coverage were obtained using a virial equation, while the values at various surface coverages were obtained from the van't Hoff isochore. The values were in the range 3.9-5.2 kJ mol(-1) for the carbons studied. The thermodynamics of the adsorption process are discussed in relation to temperature limitations for hydrogen storage applications. The maximum amounts of hydrogen adsorbed correlated with the micropore volume obtained from extrapolation of the Dubinin-Radushkevich equation for carbon dioxide adsorption. Functional groups have a small detrimental effect on hydrogen adsorption, and this is related to decreased adsorbate-adsorbent and increased adsorbate-adsorbate interactions.

  10. Controlling the BET Surface Area of Porous Carbon by Using the Cd/C Ratio of a Cd-MOF Precursor and Enhancing the Capacitance by Activation with KOH.

    PubMed

    Li, Zuo-Xi; Zhang, Xue; Liu, Yi-Chen; Zou, Kang-Yu; Yue, Man-Li

    2016-12-05

    Herein, four new cadmium metal-organic frameworks (Cd-MOFs), [Cd(bib)(bdc)]∞ (1), [Cd(bbib)(bdc)(H2 O)]∞ (2), [Cd(bibp)(bdc)]∞ (3), and [Cd2 (bbibp)2 (bdc)2 (H2 O)]∞ (4), have been constructed from the reaction of Cd(NO3 )2 ⋅4 H2 O with 1,4-benzenedicarboxylate (H2 bdc) and structure-related bis(imidazole) ligands (1,4-bis(imidazol-1-yl)benzene (bib), 1,4-bis(benzoimidazol-1-yl)benzene (bbib), 4,4'-bis(imidazol-1-yl)biphenyl (bibp), and 4,4'-bis(benzoimidazol-1-yl)biphenyl (bbibp)) under solvothermal conditions. Cd-MOF 1 shows a 2D (4,4) lattice with parallel interpenetration, whereas 2 displays an interesting 3D interpenetrating dia network, 3 exhibits an unusual 3D interpenetrating dmp network, and 4 presents a 3D self-catenated pillar-layered framework with a Schäfli symbol of [4(3) ⋅6(3) ]2 ⋅[4(6) ⋅6(16) ⋅8(6) ]. The structural diversity indicates that the backbone of the bis(imidazole) ligand (including the terminal group and spacer) plays a crucial role in the assembly of mixed-ligand frameworks. By using the pore-forming effect of cadmium vapor, for the first time we have utilized these Cd-MOFs as precursors to further prepare porous carbon materials (PCs) in a calcination-thermolysis procedure. These PCs show different porous features that correspond to the topological structures of Cd-MOFs. Significantly, it was found that the specific surface area and capacitance of PCs are tuned by the Cd/C ratio of the MOF. Furthermore, the as-synthesized PCs were processed with KOH to obtain activated porous carbon materials (APCs) with higher specific surface area and porosity, which greatly promoted the energy-storage capacity. After full characterization, we found that APC-bib displays the largest specific surface area (1290 m(2)  g(-1) ) and total pore volume (1.37 cm(3)  g(-1) ) of this series of carbon materials. Consequently, APC-bib demonstrates the highest specific capacitance of 164 F g(-1) at a current density of 0.5

  11. Converting Poultry Litter into Activated Carbon

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Disposal of animal manure is one of the biggest problems facing agriculture today. Now new technology has been designed to covert manure into environmentally friendly and highly valued activated carbon. When pelletized and activated under specific conditions, the litter becomes a highly porous mat...

  12. Stability of Carbon Incorpoated Semipolar GaN(1101) Surface

    NASA Astrophysics Data System (ADS)

    Akiyama, Toru; Nakamura, Kohji; Ito, Tomonori

    2011-08-01

    The structural stability of carbon incorporated GaN(1101) surfaces is theoretically investigated by performing first-principles pseudopotential calculations. The calculated surface formation energies taking account of the metal organic vapor phase epitaxy conditions demonstrate that several carbon incorporated surfaces are stabilized depending on the growth conditions. Using surface phase diagrams, which are obtained by comparing the calculated adsorption energy with vapor-phase chemical potentials, we find that the semipolar surface forms NH2 and CH2 below ˜1660 K while the polar GaN(0001) surface with CH3 is stabilized below ˜1550 K. This difference could be one of possible explanations for p-type doping on the semipolar GaN(1101) surface.

  13. 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.

  14. 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.

  15. Heterologous expression of the hydrophobin FcHyd5p from Fusarium culmorum in Pichia pastoris and evaluation of its surface activity and contribution to gushing of carbonated beverages.

    PubMed

    Stübner, Matthias; Lutterschmid, Georg; Vogel, Rudi F; Niessen, Ludwig

    2010-06-30

    The class II hydrophobin FcHyd5p from Fusarium culmorum was heterologously expressed by Pichia pastoris. Transcription of the recombinant gene was confirmed by RT-PCR and expression of FcHyd5p was demonstrated using SDS-PAGE and immuno-staining with 6 x His-tag antibodies. FcHyd5p was purified and concentrated by dialysis, isoelectric focussing and the use of ultra filtration. It was demonstrated that FcHyd5p is able to change the hydrophopic properties of surfaces rendering them wettable after coating with the supernatant of recombinant P. pastoris cultures. Furthermore, due to its surface activity, FcHyd5p was able to stabilise air bubbles in aqueous solutions. The supernatant of a culture medium containing a FcHyd5p producing P. pastoris clone remained turbid for 24h and the foam stable for more than 72 h after the treatment with a homogeniser, whereas the liquid of the wild type strain clarified after 10 min and the foam disintegrated after 2h. Finally it was demonstrated, that FcHyd5p can induce spontaneous overfoaming of carbonated liquids, referred to as gushing. Addition of 2 mg freeze-dried culture supernatant from a FcHyd5p producing P. pastoris clone resulted in a lost volume of 252 ml +/- 20 per 500 ml of beer (50%) and 179 ml +/- 7 per 330 ml of carbonated water (54%), respectively. Neither untreated beer/water, nor beer/water treated with freeze-dried culture supernatant from the wild type strain showed any gushing. Furthermore, addition of 215 microg highly purified FcHyd5p resulted in a lost volume of 77 ml +/- 40 per 500 ml beer (15%).

  16. Plasma-Surface Interactions of Hydrogenated Carbon

    DTIC Science & Technology

    2009-01-01

    with a collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. 1...rate of progress in the area of tritium re- moval, together with favorable results from divertor tokamaks with high atomic number (e.g. tungsten) walls...hydrogen ions and thermal atomic hydrogen, both for pure carbon as well as mixed materials systems . Properly bench- marked molecular dynamics (MD

  17. 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.

  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. Comparison on pore development of activated carbon produced by chemical and physical activation from palm empty fruit bunch

    NASA Astrophysics Data System (ADS)

    Hidayat, A.; Sutrisno, B.

    2016-11-01

    It is well-known that activated carbon is considered to be the general adsorbent due to the large range of applications. Numerous works are being continuously published concerning its use as adsorbent for: treatment of potable water; purification of air; retention of toxins by respirators; removal of organic and inorganic pollutants from flue gases and industrial waste gases and water; recuperation of solvents and hydrocarbons volatilized from petroleum derivatives; catalysis; separation of gas mixtures (molecularsieve activated carbons); storage of natural gas and hydrogen; energy storage in supercapacitors; recovery of gold, silver and othernoble metals; etc. This work presents producing activated carbons from palm empty fruit bunch using both physical activation with CO2 and chemical activation with KOH. The resultant activated carbons were characterized by measuring their porosities and pore size distributions. A comparison of the textural characteristics and surface chemistry of the activated carbon from palm empty fruit bunch by the CO2 and the KOH activation leads to the following findings: An activated carbon by the CO2 activation under the optimum conditions has a BET surface area of 717 m2/g, while that by the KOH activation has a BET surface area of 613 m2/g. The CO2 activation generated a highly microporous carbon (92%) with a Type-I isotherm, while the KOH activation generated a mesoporous one (70%) with a type-IV isotherm, the pore volumes are 0.2135 and 0.7426 cm3.g-1 respectively. The average pore size of the activated carbons is 2.72 and 2.56 nm for KOH activation and CO2 activation, respectively. The FT-IR spectra indicated significant variation in the surface functional groups are quite different for the KOH activated and CO2 activated carbons.

  20. Understanding the Effects of Surface Chemistry and Microstructure on the Activity and Stability of Pt Electrocatalysts on Non-Carbon Supports

    SciTech Connect

    Mustain, William

    2015-02-12

    The objective of this project is to elucidate the effects of the chemical composition and microstructure of the electrocatalyst support on the activity, stability and utilization of supported Pt clusters.

  1. Chemical modification of sputtered amorphous-carbon surfaces

    NASA Astrophysics Data System (ADS)

    Leezenberg, Pieter B.; Johnston, William H.; Tyndall, George W.

    2001-03-01

    Methods to chemically passivate the surfaces of amorphous-carbon films (a-C) produced by dc magnetron sputtering were studied. The chemical composition of carbon surfaces produced via sputtering are dependent upon the environment to which the carbon is exposed immediately following deposition. When the sputtered film is vented to ambient conditions, free radicals produced at the surface during the deposition process are quenched by reaction with oxygen and/or water to form an oxidized, hydrophilic surface. If the sputtered carbon film is, however, exposed to a reactive gas prior to venting to ambient, the chemical nature of the resulting surface can be modified substantially. Specifically, a less highly oxidized and much more hydrophobic carbon surface is produced when the surface free radicals are quenched via either an addition reaction (demonstrated with a fluorinated olefin) or a hydrogen abstraction reaction (demonstrated with two alkyl amines). Chemical modification of amorphous-carbon films can also be accomplished by performing the sputtering in a reactive plasma formed from mixtures of argon with molecular hydrogen, amines, and perfluorocarbons. The elemental composition of these films, and the relative reactivity of the surfaces formed, were investigated via x-ray photoelectron spectroscopy and contact-angle goniometry, respectively. In the case of sputtering with a mixture of argon and hydrogen, increasing the hydrogen flow results in an increase in the amount of hydrogen incorporated into the carbon film and a decrease in the surface free energy. Sputtering in diethylamine produces an amorphous-carbon film into which nitrogen is incorporated. The free energies of the a-C:N surfaces produced in this process are similar to those of the a-C:H films. Sputtering in a fluorocarbon vapor results in the incorporation of fluorine into the film structure and the formation of very low free-energy surfaces. Increasing the concentration of the fluorocarbon in the

  2. Carbon nanotube oscillator surface profiling device and method of use

    DOEpatents

    Popescu, Adrian [Tampa, FL; Woods, Lilia M [Tampa, FL; Bondarev, Igor V [Fuquay Varina, NC

    2011-11-15

    The proposed device is based on a carbon nanotube oscillator consisting of a finite length outer stationary nanotube and a finite length inner oscillating nanotube. Its main function is to measure changes in the characteristics of the motion of the carbon nanotube oscillating near a sample surface, and profile the roughness of this surface. The device operates in a non-contact mode, thus it can be virtually non-wear and non-fatigued system. It is an alternative to the existing atomic force microscope (AFM) tips used to scan surfaces to determine their roughness.

  3. 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.

  4. Ultrahigh Surface Area Three-Dimensional Porous Graphitic Carbon from Conjugated Polymeric Molecular Framework

    PubMed Central

    2015-01-01

    Porous graphitic carbon is essential for many applications such as energy storage devices, catalysts, and sorbents. However, current graphitic carbons are limited by low conductivity, low surface area, and ineffective pore structure. Here we report a scalable synthesis of porous graphitic carbons using a conjugated polymeric molecular framework as precursor. The multivalent cross-linker and rigid conjugated framework help to maintain micro- and mesoporous structures, while promoting graphitization during carbonization and chemical activation. The above unique design results in a class of highly graphitic carbons at temperature as low as 800 °C with record-high surface area (4073 m2 g–1), large pore volume (2.26 cm–3), and hierarchical pore architecture. Such carbons simultaneously exhibit electrical conductivity >3 times more than activated carbons, very high electrochemical activity at high mass loading, and high stability, as demonstrated by supercapacitors and lithium–sulfur batteries with excellent performance. Moreover, the synthesis can be readily tuned to make a broad range of graphitic carbons with desired structures and compositions for many applications. PMID:27162953

  5. Removal of nitrate from aqueous solutions by activated carbon prepared from sugar beet bagasse.

    PubMed

    Demiral, Hakan; Gündüzoğlu, Gül

    2010-03-01

    In this study, activated carbons were prepared from sugar beet bagasse by chemical activation and the prepared activated carbons were used to remove nitrate from aqueous solutions. In chemical activation, ZnCl(2) was used as chemical agent. The effects of impregnation ratio and activation temperature were investigated. The produced activated carbons were characterized by measuring their porosities and pore size distributions. The microstructure of the activated carbons was examined by scanning electron microscopy (SEM). The maximum specific surface area of the activated carbon was about 1826m(2)/g at 700 degrees C and at an impregnation ratio of 3:1. The resulting activated carbon was used for removal of nitrate from aqueous solution. The effects of pH, temperature and contact time were investigated. Isotherm studies were carried out and the data were analyzed by Langmuir, Freundlich and Temkin equations. Three simplified kinetic models were tested to investigate the adsorption mechanism.

  6. 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.

  7. Adsorption characteristics of acetone, chloroform and acetonitrile on sludge-derived adsorbent, commercial granular activated carbon and activated carbon fibers.

    PubMed

    Tsai, Jiun-Horng; Chiang, Hsiu-Mei; Huang, Guan-Yinag; Chiang, Hung-Lung

    2008-06-15

    The adsorption characteristics of chloroform, acetone, and acetonitrile on commercial activated carbon (C1), two types of activated carbon fibers (F1 and F2), and sludge adsorbent (S1) was investigated. The chloroform influent concentration ranged from 90 to 7800 ppm and the acetone concentration from 80 to 6900 ppm; the sequence of the adsorption capacity of chloroform and acetone on adsorbents was F2>F1 approximately C1 approximately S1. The adsorption capacity of acetonitrile ranged from 4 to 100 mg/g, corresponding to the influent range from 43 to 2700 ppm for C1, S1, and F1. The acetonitrile adsorption capacity of F2 was approximately 20% higher than that of the other adsorbents at temperatures<30 degrees C. The Freundlich equation fit the data better than the Langmuir and Dubinin-Radushkevich (D-R) equations. The adsorption rate of carbon fibers is higher than that of the other adsorbents due to their smaller fiber diameter and higher surface area. The micropore diffusion coefficient of VOC on activated carbon and sludge adsorbent was approximately 10(-4) cm2 s(-1). The diffusion coefficient of VOC on carbon fibers ranged from 10(-8) to 10(-7) cm2 s(-1). The small carbon fiber pore size corresponds to a smaller diffusion coefficient.

  8. CARBON SEQUESTRATION ON SURFACE MINE LANDS

    SciTech Connect

    Donald H. Graves; Christopher Barton; Richard Sweigard; Richard Warner

    2005-06-22

    An area planted in 2004 on Bent Mountain in Pike County was shifted to the Department of Energy project to centralize an area to become a demonstration site. An additional 98.3 acres were planted on Peabody lands in western Kentucky and Bent Mountain to bring the total area under study by this project to 556.5 acres as indicated in Table 2. Major efforts this quarter include the implementation of new plots that will examine the influence of differing geologic material on tree growth and survival, water quality and quantity and carbon sequestration. Normal monitoring and maintenance was conducted and additional instrumentation was installed to monitor the new areas planted.

  9. 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.

  10. Characteristics of activated carbon prepared from pistachio-nut shell by zinc chloride activation under nitrogen and vacuum conditions.

    PubMed

    Lua, Aik Chong; Yang, Ting

    2005-10-15

    Activated carbons with well-developed pore structures were prepared from pistachio-nut shells by chemical activation using zinc chloride under both nitrogen atmosphere and vacuum conditions. The effects of preparation parameters on the carbon pore structure were studied in order to optimize these parameters. It was found that under vacuum conditions, the characteristics of the activated carbons produced are better than those under nitrogen atmosphere. The impregnation ratio, the activation temperature, and the activation hold time are the important parameters that influence the characteristics of the activated carbons. The optimum experimental conditions for preparing predominantly microporous activated carbons with high pore surface area and micropore volume are an impregnation ratio of 0.75, an activation temperature of 400 degrees C, and a hold time of 1 h. Under these conditions, the BET surface areas of the carbons activated under nitrogen atmosphere and vacuum conditions were 1635.37 and 1647.16 m2/g, respectively. However, at a ZnCl2 impregnation ratio of 1.5, a furnace temperature of 500 degrees C, and a hold time of 2 h, the predominantly mesoporous activated carbon prepared under vacuum condition had a BET surface area of 2527 m2/g. Fourier transform infrared spectra were used to detect changes in the surface functional groups of the samples during the different preparation stages.

  11. Nanoscale Etching and Indentation of Silicon Surfaces with Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Dzegilenko, Fedor N.; Srivastava, Deepak; Saini, Subhash

    1998-01-01

    The possibility of nanolithography of silicon and germanium surfaces with bare carbon nanotube tips of scanning probe microscopy devices is considered with large scale classical molecular dynamics (MD) simulations employing Tersoff's reactive many-body potential for heteroatomic C/Si/Ge system. Lithography plays a key role in semiconductor manufacturing, and it is expected that future molecular and quantum electronic devices will be fabricated with nanolithographic and nanodeposition techniques. Carbon nanotubes, rolled up sheets of graphene made of carbon, are excellent candidates for use in nanolithography because they are extremely strong along axial direction and yet extremely elastic along radial direction. In the simulations, the interaction of a carbon nanotube tip with silicon surfaces is explored in two regimes. In the first scenario, the nanotubes barely touch the surface, while in the second they are pushed into the surface to make "nano holes". The first - gentle scenario mimics the nanotube-surface chemical reaction induced by the vertical mechanical manipulation of the nanotube. The second -digging - scenario intends to study the indentation profiles. The following results are reported in the two cases. In the first regime, depending on the surface impact site, two major outcomes outcomes are the selective removal of either a single surface atom or a surface dimer off the silicon surface. In the second regime, the indentation of a silicon substrate by the nanotube is observed. Upon the nanotube withdrawal, several surface silicon atoms are adsorbed at the tip of the nanotube causing significant rearrangements of atoms comprising the surface layer of the silicon substrate. The results are explained in terms of relative strength of C-C, C-Si, and Si-Si bonds. The proposed method is very robust and does not require applied voltage between the nanotube tips and the surface. The implications of the reported controllable etching and hole-creating for

  12. Direct measurement of surface carbon concentrations. [in lunar soil

    NASA Technical Reports Server (NTRS)

    Filleux, C.; Tombrello, T. A.; Burnett, D. S.

    1977-01-01

    Measurements of surface concentrations of carbon in lunar soils and soil breccias provide information on the origin of carbon in the regolith. The reaction C-12 (d, p sub zero) is used to measure 'surface' and 'volume' concentrations in lunar samples. This method has a depth resolution of 1 micron, which permits only a 'surface' and a 'volume' component to be measured. Three of four Apollo 16 double drive tube samples show a surface carbon concentration of about 8 by 10 to the 14th power/sq cm, whereas the fourth sample gave 4 by 10 to the 14th power/sq cm. It can be convincingly shown that the measured concentration does not originate from fluorocarbon or hydrocarbon contaminants. Surface adsorbed layers of CO or CO2 are removed by a sputter cleaning procedure using a 2-MeV F beam. It is shown that the residual C concentration of 8 by 10 to the 14th power/sq cm cannot be further reduced by increased F fluence, and it is therefore concluded that it is truly lunar. If one assumes that the measured surface C concentration is a steady-state concentration determined only by a balance between solar-wind implantation and sputtering, a sputter erosion rate of 0.1 A/yr is obtained. However, it would be more profitable to use an independently derived sputter erosion rate to test the hypothesis of a solar-wind origin of the surface carbon.

  13. Surface selective membranes for carbon dioxide separation

    SciTech Connect

    Luebke, D.R.; Pennline, H.W.; Myers, C.R.

    2005-09-01

    In this study, hybrid membranes have been developed for the selective separation of CO2 from mixtures containing H2. Beginning with commercially available Pall alumina membrane tubes with nominal pore diameter of 5 nm, hybrids were produced by silation with a variety of functionalities designed to facilitate the selective adsorption of CO2 onto the pore surface. The goal is to produce a membrane which can harness the power of surface diffusion to give the selectivity of polymer membranes with the permeance of inorganic membranes.

  14. Removal of arsenic(V) from aqueous solutions using iron-oxide-coated modified activated carbon.

    PubMed

    Zhang, Q L; Gao, Nai-Yun; Lin, Y C; Xu, Bin; Le, Lin-sheng

    2007-08-01

    Removal of arsenic(V) from aqueous solutions was evaluated with the following three different sorption materials: coal-based activated carbon 12 x 40 (activated carbon), iron(II) oxide (FeO)/activated carbon-H, and iron oxide. The apparent characteristics and physical chemistry performances of these adsorbents were investigated by X-ray diffraction, nitrogen adsorption, and scanning electronic microscope. Also, batch experiments for arsenic removal were performed, and the effects of pH value on arsenic(V) removal were studied. The results suggest that the main phases of the iron oxide surface are magnetite, maghemite, hematite, and goethite; fine and uniform iron oxide particles can cover activated carbon surfaces and affect the surface area or pore structures of activated carbon; adsorption kinetics obey a pseudo-first-order rate equation; and adsorption capacities of adsorbents are affected by the values of pH. The optimum value of pH for iron oxide lies in a narrow range between 4.0 and 5.5, and arsenic(V) removal by FeO/activated carbon-H is ideal and stable in the pH range 3 to 7, while activated carbon has the lowest adsorption capacity in the entire pH range. Also, the adsorption characteristics of FeO/activated carbon-H composites and virgin activated carbon match well the Langmuir adsorption model, while those of iron oxide fit well the Freundlich adsorption model.

  15. Revibrational Spectra of Molecules Sputtered of Carbon Surfaces

    NASA Astrophysics Data System (ADS)

    Krstic, Predrag

    2008-10-01

    Irradiation of the carbon surfaces by hydrogen isotopes results in processes of crucial importance for the carbon based divertor tiles of a fusion reactor. Thus the sputtering and implantation, result in erosion, plasma pollution, and tritium retention, as well as carbon deposition all over the reactor first wall. The molecules chemically sputtered upon impact of deuterium of deuterated carbon surface are various hydrocarbons as well as We study the translational and rovibrational energy and angular spectra of sputtered molecules. The energy distributions of ejected molecules confirm the partial thermalization of the impact cascade. Sputtered hydrocarbon molecules have rovibrational energies in the range 1.5-2 eV, with relatively cold translational and rotational motion, close to 0.5 eV. In contrast, translational and rovibrational energies of sputtered deuterium molecules are close to 1 eV, with approximate equipartition between rotational and vibrational modes.

  16. Effect of nitric acid treatment on activated carbon derived from oil palm shell

    NASA Astrophysics Data System (ADS)

    Allwar, Allwar; Hartati, Retno; Fatimah, Is

    2017-03-01

    The primary object of this work is to study the effect of nitric acid on the porous and morphology structure of activated carbon. Production of activated carbon from oil palm shell was prepared with pyrolysis process at temperature 900°C and by introduction of 10 M nitric acid. Determination of surface area, pore volume and pore size distribution of activated carbon was conducted by the N2 adsorption-desorption isotherm at 77 K. Morphology structure and elemental micro-analysis of activated carbon were estimated by Scanning Electron Microscopy (SEM) and energy dispersive X-ray (EDX), respectively. The result shows that activated carbon after treating with nitric acid proved an increasing porous characteristics involving surface area, pore volume and pore size distribution. It also could remove the contaminants including metals and exhibit an increasing of pores and crevices all over the surface.

  17. Constraining surface carbon fluxes using in situ measurements of carbonyl sulfide and carbon dioxide

    NASA Astrophysics Data System (ADS)

    Berkelhammer, M.; Asaf, D.; Still, C.; Montzka, S.; Noone, D.; Gupta, M.; Provencal, R.; Chen, H.; Yakir, D.

    2014-02-01

    Understanding the processes that control the terrestrial exchange of carbon is critical for assessing atmospheric CO2 budgets. Carbonyl sulfide (COS) is taken up by vegetation during photosynthesis following a pathway that mirrors CO2 but has a small or nonexistent emission component, providing a possible tracer for gross primary production. Field measurements of COS and CO2 mixing ratios were made in forest, senescent grassland, and riparian ecosystems using a laser absorption spectrometer installed in a mobile trailer. Measurements of leaf fluxes with a branch-bag gas-exchange system were made across species from 10 genera of trees, and soil fluxes were measured with a flow-through chamber. These data show (1) the existence of a narrow normalized daytime uptake ratio of COS to CO2 across vascular plant species of 1.7, providing critical information for the application of COS to estimate photosynthetic CO2 fluxes and (2) a temperature-dependent normalized uptake ratio of COS to CO2 from soils. Significant nighttime uptake of COS was observed in broad-leafed species and revealed active stomatal opening prior to sunrise. Continuous high-resolution joint measurements of COS and CO2 concentrations in the boundary layer are used here alongside the flux measurements to partition the influence that leaf and soil fluxes and entrainment of air from above have on the surface carbon budget. The results provide a number of critical constraints on the processes that control surface COS exchange, which can be used to diagnose the robustness of global models that are beginning to use COS to constrain terrestrial carbon exchange.

  18. Activated carbon from vetiver roots: gas and liquid adsorption studies.

    PubMed

    Gaspard, S; Altenor, S; Dawson, E A; Barnes, P A; Ouensanga, A

    2007-06-01

    Large quantities of lignocellulosic residues result from the industrial production of essential oil from vetiver grass (Vetiveria zizanioides) roots. These residues could be used for the production of activated carbon. The yield of char obtained after vetiver roots pyrolysis follows an equation recently developed [A. Ouensanga, L. Largitte, M.A. Arsene, The dependence of char yield on the amounts of components in precursors for pyrolysed tropical fruit stones and seeds, Micropor. Mesopor. Mater. 59 (2003) 85-91]. The N(2) adsorption isotherm follows either the Freundlich law K(F)P(alpha) which is the small alpha equation limit of a Weibull shaped isotherm or the classical BET isotherm. The surface area of the activated carbons are determined using the BET method. The K(F) value is proportional to the BET surface area. The alpha value increases slightly when the burn-off increases and also when there is a clear increase in the micropore distribution width.

  19. Selection of pecan shell based activated carbons for removal of organic and inorganic impurities from simulated well-water

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Activated carbons are a byproduct from pyrolysis and have value as a purifying agent. The effectiveness of activated carbons is dependent on feedstock selection and pyrolysis conditions that modify its surface properties. Therefore, pecan shell-based activated carbons (PSACs) were prepared by soakin...

  20. 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.

  1. 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.

  2. The Effect of Anodic Surface Treatment on the Oxidation of Catechols at Ultrasmall Carbon Ring Electrodes

    DTIC Science & Technology

    1991-07-09

    selectivity. A model of the surface formed following anodic oxidation is consistent with previous models involving both surface cleanliness and carbon...involving both surface cleanliness and carbon structure orientation. 2 INTRODUCTION Because of the vast electroanalytical utility of carbon electrodes...of the electron transfer rate following treatment are a function of the surface cleanliness and the orientation of the carbon structure

  3. Surface properties of mesoporous carbon-silica gel adsorbents

    SciTech Connect

    Leboda, R.; Turov, V.V.; Charmas, B.; Skubiszewska-Zieba, J.; Gun'ko, V.M.

    2000-03-01

    Carbon/silica (carbosil) samples prepared utilizing mesoporous silica gel (Si-60) modified by methylene chloride pyrolysis were studied by nitrogen adsorption, quasi-isothermal thermogravimetry, p-nitrophenol adsorption from aqueous solution, and {sup 1}H NMR methods. The structural characteristics and other properties of carbosils depend markedly on the synthetic conditions and the amount of carbon deposited. The changes in the pore size distribution with increasing carbon concentration suggest grafting of carbon mainly in pores, leading to diminution of the mesopore radii. However, heating pure silica gel at the pyrolysis temperature of 550 C leads to an increase in the pore radii. The quasi-isothermal thermogravimetry and {sup 1}H NMR spectroscopy methods used to investigate the water layers on carbosils showed a significant capability of carbosils to adsorb water despite a relatively large content of the hydrophobic carbon deposit, which represents a nonuniform layer incompletely covering the oxide surface.

  4. Understanding reduction of carbon tetrachloride at nickel surfaces.

    PubMed

    Wang, Jiankang; Blowers, Paul; Farrell, James

    2004-03-01

    Nickel has been found to be an effective cathode material and catalyst for reductive destruction of chlorinated solvents in contaminated water. This study investigated reductive dechlorination of carbon tetrachloride (CT) at a nickel rotating disk electrode using chronoamperometry and electrochemical impedance spectroscopy. Chronoamperometry experiments were performed to determine rates of CT reduction as a function of the electrode potential, pH, CT concentration, and temperature. The reaction products of CT dechlorination were 95 +/- 4% methane and 4.1 +/- 2.5% chloroform. Only trace levels of methylene chloride and chloromethane were produced, indicating that sequential hydrogenolysis was not the predominant pathway for methane production. Electrochemical impedance spectroscopy showed that the rate-limiting step for methane production was the transfer of the first electron to a physically adsorbed CT molecule. The temperature independence of the electron transfer coefficient and the decreasing activation energy with decreasing electrode potential indicated that the rate-limiting step involved an outer-sphere electron transfer. At neutral pH values, oxides inactivated much of the electrode surface for both CT reduction and hydrogen evolution. At lower pH values, oxide dissolution served to increase the electroactive surface area of the disk electrode. Anson analysis and kinetic modeling showed that CT adsorption to electroactive sites was a nonlinear function of the CT concentration and was in equilibrium with the bulk solution. CT dechlorination rates on nickel electrodes were 16 times slower than those on iron electrodes under similar conditions. However, CT reactions at nickel surfaces produced predominantly methane as the first detectable product, while reduction at iron surfaces produced chloroform. These results suggest that, although nickel is not a catalyst for the rate-limiting step for CT dechlorination, it may serve a catalytic role in subsequent

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

    PubMed

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

    2015-01-23

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

  6. Water and Carbon Dioxide Adsorption at Olivine Surfaces

    SciTech Connect

    Kerisit, Sebastien N.; Bylaska, Eric J.; Felmy, Andrew R.

    2013-11-14

    Plane-wave density functional theory (DFT) calculations were performed to simulate water and carbon dioxide adsorption at the (010) surface of five olivine minerals, namely, forsterite (Mg2SiO4), calcio-olivine (Ca2SiO4), tephroite (Mn2SiO4), fayalite (Fe2SiO4), and Co-olivine (Co2SiO4). Adsorption energies per water molecule obtained from energy minimizations varied from -78 kJ mol-1 for fayalite to -128 kJ mol-1 for calcio-olivine at sub-monolayer coverage and became less exothermic as coverage increased. In contrast, carbon dioxide adsorption energies at sub-monolayer coverage ranged from -20 kJ mol-1 for fayalite to -59 kJ mol-1 for calcio-olivine. Therefore, the DFT calculations show a strong driving force for carbon dioxide displacement by water at the surface of all olivine minerals in a competitive adsorption scenario. Additionally, adsorption energies for both water and carbon dioxide were found to be more exothermic for the alkaline-earth (AE) olivines than for the transition-metal (TM) olivines and to not correlate with the solvation enthalpies of the corresponding divalent cations. However, a correlation was obtained with the charge of the surface divalent cation indicating that the more ionic character of the AE cations in the olivine structure relative to the TM cations leads to greater interactions with adsorbed water and carbon dioxide molecules at the surface and thus more exothermic adsorption energies for the AE olivines. For calcio-olivine, which exhibits the highest divalent cation charge of the five olivines, ab initio molecular dynamics simulations showed that this effect leads both water and carbon dioxide to react with the surface and form hydroxyl groups and a carbonate-like species, respectively.

  7. Comparison of adsorption behavior of PCDD/Fs on carbon nanotubes and activated carbons in a bench-scale dioxin generating system.

    PubMed

    Zhou, Xujian; Li, Xiaodong; Xu, Shuaixi; Zhao, Xiyuan; Ni, Mingjiang; Cen, Kefa

    2015-07-01

    Porous carbon-based materials are commonly used to remove various organic and inorganic pollutants from gaseous and liquid effluents and products. In this study, the adsorption of dioxins on both activated carbons and multi-walled carbon nanotube was internally compared, via series of bench scale experiments. A laboratory-scale dioxin generator was applied to generate PCDD/Fs with constant concentration (8.3 ng I-TEQ/Nm(3)). The results confirm that high-chlorinated congeners are more easily adsorbed on both activated carbons and carbon nanotubes than low-chlorinated congeners. Carbon nanotubes also achieved higher adsorption efficiency than activated carbons even though they have smaller BET-surface. Carbon nanotubes reached the total removal efficiency over 86.8 % to be compared with removal efficiencies of only 70.0 and 54.2 % for the two other activated carbons tested. In addition, because of different adsorption mechanisms, the removal efficiencies of carbon nanotubes dropped more slowly with time than was the case for activated carbons. It could be attributed to the abundant mesopores distributed in the surface of carbon nanotubes. They enhanced the pore filled process of dioxin molecules during adsorption. In addition, strong interactions between the two benzene rings of dioxin molecules and the hexagonal arrays of carbon atoms in the surface make carbon nanotubes have bigger adsorption capacity.

  8. Supercritical Carbon Dioxide Regeneration of Activated Carbon Loaded with Contaminants from Rocky Mountain Arsenal Well Water.

    DTIC Science & Technology

    1982-05-01

    15 111-7 GRANULAR ACTIVATED CARBON ADSORPTION ISOTHERMS THERMALLY REACTIVATED CARBON .............. 16 I IV-1 PROCESS FLOW DIAGRAM FOR... PROCESSING COST OF ACTIVATED CHARCOAL REGENERATION BY SUPERCRITICAL CARBON DIOXIDE PROCESS ........................... 25 l IV-4 SENSITIVITY OF GAC...regenerate adsorbents such as granular activated carbon loaded with a broad variety of organic adsorbates. This regeneration process uses a supercritical

  9. Spectroscopic study of proflavine adsorption on the carbon nanotube surface.

    PubMed

    Buchelnikov, Anatoly S; Dovbeshko, Galina I; Voronin, Dmitry P; Trachevsky, Vladimir V; Kostjukov, Viktor V; Evstigneev, Maxim P

    2014-01-01

    Despite the fact that non-covalent interactions between various aromatic compounds and carbon nanotubes are being extensively investigated now, there is still a lack of understanding about the nature of such interactions. The present paper sheds light on one of the possible mechanisms of interaction between the typical aromatic dye proflavine and the carbon nanotube surface, namely, π-stacking between aromatic rings of these compounds. To investigate such a complexation, a qualitative analysis was performed by means of ultraviolet visible, infrared, and nuclear magnetic resonance spectroscopy. The data obtained suggest that π-stacking brings the major contribution to the stabilization of the complex between proflavine and the carbon nanotube.

  10. SURFACE MORPHOLOGY OF CARBON FIBER POLYMER COMPOSITES AFTER LASER STRUCTURING

    SciTech Connect

    Sabau, Adrian S; Chen, Jian; Jones, Jonaaron F.; Alexandra, Hackett; Jellison Jr, Gerald Earle; Daniel, Claus; Warren, Charles David; Rehkopf, Jackie D.

    2015-01-01

    The increasing use of Carbon Fiber Polymer Composite (CFPC) as a lightweight material in automotive and aerospace industries requires the control of surface morphology. In this study, the composites surface was prepared by ablating the resin in the top fiber layer of the composite using an Nd:YAG laser. The CFPC specimens with T700S carbon fiber and Prepreg - T83 resin (epoxy) were supplied by Plasan Carbon Composites, Inc. as 4 ply thick, 0/90o plaques. The effect of laser fluence, scanning speed, and wavelength was investigated to remove resin without an excessive damage of the fibers. In addition, resin ablation due to the power variation created by a laser interference technique is presented. Optical property measurements, optical micrographs, 3D imaging, and high-resolution optical profiler images were used to study the effect of the laser processing on the surface morphology.

  11. Adsorption of Hydantoins on Activated Carbon,

    DTIC Science & Technology

    1985-05-01

    performed for single solute, bisolute, and trisolute solutions as well as an undiluted coal gasification wastewater containing predominantly hydantoin...hydantoin, 5,5-dimethylhydantoin, and 5-ethyl-5-methylhydantoin. Absorption using activated carbon did not appear to be an effective treatment process for the removal of hydantoins from the coal gasification wastewater.

  12. ENGINEERING BULLETIN: GRANULAR ACTIVATED CARBON TREATMENT

    EPA Science Inventory

    Granular activated carbon (GAC) treatment is a physicochemical process that removes a wide variety of contaminants by adsorbing them from liquid and gas streams [1, p. 6-3]. This treatment is most commonly used to separate organic contaminants from water or air; however, it can b...

  13. 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...

  14. 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...

  15. Nitrogen-Containing Carbon Nanotube Synthesized from Polymelem and Activated Carbon Derived from Polymer Blend

    NASA Astrophysics Data System (ADS)

    Qin, Nan

    Polymelem possesses a polymeric structure of heptazine (C6N 7) rings connected by amine bridges and our study has demonstrated that it is a promising precursor for the synthesis of nitrogen-containing carbon materials. Nitrogen-containing carbon nanotube (NCNT) was produced by pyrolyzing polymelem as a dual source of carbon and nitrogen with Raney nickel in a high pressure stainless steel cell. Activated carbon was produced from poly(ether ether ketone)/poly(ether imide) (PEEK/PEI blend) and incorporated with polymelem to enhance the hydrogen adsorption. Polymelem was successfully synthesized by pyrolyzing melamine at 450--650 °C and its structure was elucidated by 13C solid state NMR, FTIR, and XRD. The molecular weight determined by a novel LDI MS equipped with a LIFT mode illuminated that polymelem has both linear and cyclic connectivity with a degree of polymerization of 2--5 depending on the synthesis temperature. The decomposition products of polymelem were determined to be cyanoamide, dicyanoamide, and tricyanoamine. Tricyanoamine is the smallest carbon nitride molecule and has been experimentally confirmed for the first time in this study. When polymelem was decomposed in the presence of Raney nickel, homogenous NCNT with nitrogen content of ˜ 4--19 atom% was produced. A mechanism based on a detail analysis of the TEM images at different growth stages proposed that the NCNT propagated via a tip-growth mechanism originating at the nano-domains within the Raney nickel, and was accompanied with the aggregation of the nickel catalysts. Such NCNT exhibited a cup-stack wall structure paired with a compartmental feature. The nitrogen content, tube diameter and wall thickness greatly depended on synthesis conditions. The activated carbon derived from PEEK/PEI blend demonstrated a surface area up to ˜3000 m2/g, and average pore size of < 20 A. Such activated carbon exhibited a hydrogen storage capacity of up to 6.47 wt% at 40 bar, 77 K. The activated carbon has

  16. Atypical Hydrogen Uptake on Chemically Activated, Ultramicroporous Carbon

    SciTech Connect

    Bhat, Vinay V; Contescu, Cristian I; Gallego, Nidia C; Baker, Frederick S

    2010-01-01

    Hydrogen adsorption at near-ambient temperatures on ultramicroporous carbon (UMC), derived through secondary chemical activation from a wood-based activated carbon was studied using volumetric and gravimetric methods. The results showed that physisorption is accompanied by a process of different nature that causes slow uptake at high pressures and hysteresis on desorption. In combination, this results in unusually high levels of hydrogen uptake at near-ambient temperatures and pressures (e.g. up to 0.8 wt % at 25 oC and 2 MPa). The heat of adsorption corresponding to the slow process leading to high uptake (17 20 kJ/mol) is higher than usually reported for carbon materials, but the adsorption kinetics is slow, and the isotherms exhibit pronounced hysteresis. These unusual properties were attributed to contributions from polarization-enhanced physisorption caused by traces of alkali metals residual from chemical activation. The results support the hypothesis that polarization-induced physisorption in high surface area carbons modified with traces of alkali metal ions is an alternate route for increasing the hydrogen storage capacity of carbon adsorbents.

  17. Carbon Surface Modification for Enhanced Corrosion Resistance

    DTIC Science & Technology

    2008-01-01

    LTCSS-treated 316L SS, representing a sig- nificant increase in surface hardness over the substrate material (Vickers 300 HV). To give some perspective...behavior of particular interest to the Navy. Comparison of crevice corrosion resistance for untreated 316L SS and LTCSS- treated 316L is presented in...Fig. 2. Crevice corrosion damage on an untreated 316L coupon following one week of crevice exposure is shown in the center of the figure. LTCSS

  18. 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...

  19. CHARACTERIZATION OF ACTIVATED CARBONS' PHYSICAL AND CHEMICAL PROPERTIES IN RELATION TO THEIR MERCURY ADSORPTION

    EPA Science Inventory

    The paper gives results of a characterization of the physical and chemical properties of the activated carbons used for elemental mercury (Hgo) adsorption, in order to understand the role of oxygen surface functional groups on the mechanism of Hgo adsorption by activated carbons....

  20. DEVELOPMENT OF A CL-IMPREGNATED ACTIVATED CARBON FOR ENTRAINED-FLOW CAPTURE OF ELEMENTAL MERCURY

    EPA Science Inventory

    Efforts to discern the role of an activated carbon's surface functional groups on the adsorption of elemental mercury [Hg(0)] and mercuric chloride demonstrated that chlorine (Cl) impregnation of a virgin activated carbon using dilute solutions of hydrogen chloride leads to incre...

  1. A highly permeable and enhanced surface area carbon-cloth electrode for vanadium redox flow batteries

    NASA Astrophysics Data System (ADS)

    Zhou, X. L.; Zhao, T. S.; Zeng, Y. K.; An, L.; Wei, L.

    2016-10-01

    In this work, a high-performance porous electrode, made of KOH-activated carbon-cloth, is developed for vanadium redox flow batteries (VRFBs). The macro-scale porous structure in the carbon cloth formed by weaving the carbon fibers in an ordered manner offers a low tortuosity (∼1.1) and a broad pore distribution from 5 μm to 100 μm, rendering the electrode a high hydraulic permeability and high effective ionic conductivity, which are beneficial for the electrolyte flow and ion transport through the porous electrode. The use of KOH activation method to create nano-scale pores on the carbon-fiber surfaces leads to a significant increase in the surface area for redox reactions from 2.39 m2 g-1 to 15.4 m2 g-1. The battery assembled with the present electrode delivers an energy efficiency of 80.1% and an electrolyte utilization of 74.6% at a current density of 400 mA cm-2, as opposed to an electrolyte utilization of 61.1% achieved by using a conventional carbon-paper electrode. Such a high performance is mainly attributed to the combination of the excellent mass/ion transport properties and the high surface area rendered by the present electrode. It is suggested that the KOH-activated carbon-cloth electrode is a promising candidate in redox flow batteries.

  2. Activated carbon derived from waste coffee grounds for stable methane storage.

    PubMed

    Kemp, K Christian; Baek, Seung Bin; Lee, Wang-Geun; Meyyappan, M; Kim, Kwang S

    2015-09-25

    An activated carbon material derived from waste coffee grounds is shown to be an effective and stable medium for methane storage. The sample activated at 900 °C displays a surface area of 1040.3 m(2) g(-1) and a micropore volume of 0.574 cm(3) g(-1) and exhibits a stable CH4 adsorption capacity of ∼4.2 mmol g(-1) at 3.0 MPa and a temperature range of 298 ± 10 K. The same material exhibits an impressive hydrogen storage capacity of 1.75 wt% as well at 77 K and 100 kPa. Here, we also propose a mechanism for the formation of activated carbon from spent coffee grounds. At low temperatures, the material has two distinct types with low and high surface areas; however, activation at elevated temperatures drives off the low surface area carbon, leaving behind the porous high surface area activated carbon.

  3. Decolorization of sugar syrups using commercial and sugar beet pulp based activated carbons.

    PubMed

    Mudoga, H L; Yucel, H; Kincal, N S

    2008-06-01

    Sugar syrup decolorization was studied using two commercial and eight beet pulp based activated carbons. In an attempt to relate decolorizing performances to other characteristics, surface areas, pore volumes, bulk densities and ash contents of the carbons in the powdered form; pH and electrical conductivities of their suspensions and their color adsorption properties from iodine and molasses solution were determined. The color removal capabilities of all carbons were measured at 1/100 (w/w) dosage, and isotherms were determined on better samples. The two commercial activated carbons showed different decolorization efficiencies; which could be related to their physical and chemical properties. The decolorization efficiency of beet pulp carbon prepared at 750 degrees C and activated for 5h using CO2 was much better than the others and close to the better one of the commercial activated carbons used. It is evident that beet pulp is an inexpensive potential precursor for activated carbons for use in sugar refining.

  4. Production of activated carbons from waste tyres for low temperature NOx control.

    PubMed

    Al-Rahbi, Amal S; Williams, Paul T

    2016-03-01

    Waste tyres were pyrolysed in a bench scale reactor and the product chars were chemically activated with alkali chemical agents, KOH, K2CO3, NaOH and Na2CO3 to produce waste tyre derived activated carbons. The activated carbon products were then examined in terms of their ability to adsorb NOx (NO) at low temperature (25°C) from a simulated industrial process flue gas. This study investigates the influence of surface area and porosity of the carbons produced with the different alkali chemical activating agents on NO capture from the simulated flue gas. The influence of varying the chemical activation conditions on the porous texture and corresponding NO removal from the flue gas was studied. The activated carbon sorbents were characterized in relation to BET surface area, micropore and mesopore volumes and chemical composition. The highest NO removal efficiency for the waste tyre derived activated carbons was ∼75% which was obtained with the adsorbent treated with KOH which correlated with both the highest BET surface area and largest micropore volume. In contrast, the waste tyre derived activated carbons prepared using K2CO3, NaOH and Na2CO3 alkali activating agents appeared to have little influence on NO removal from the flue gases. The results suggest problematic waste tyres, have the potential to be converted to activated carbons with NOx removal efficiency comparable with conventionally produced carbons.

  5. Production of activated carbons from pyrolysis of waste tires impregnated with potassium hydroxide.

    PubMed

    Teng, H; Lin, Y C; Hsu, L Y

    2000-11-01

    Activated carbons were produced from waste tires using a chemical activation method. The carbon production process consisted of potassium hydroxide (KOH) impregnation followed by pyrolysis in N2 at 600-900 degrees C for 0-2 hr. The activation method can produce carbons with a surface area (SA) and total pore volume as high as 470 m2/g and 0.57 cm3/g, respectively. The influence of different parameters during chemical activation, such as pyrolysis temperature, holding time, and KOH/tire ratio, on the carbon yield and the surface characteristics was explored, and the optimum preparation conditions were recommended. The pore volume of the resulting carbons generally increases with the extent of carbon gasified by KOH and its derivatives, whereas the SA increases with degree of gasification to reach a maximum value, and then decreases upon further gasification.

  6. 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.

  7. Computational Chemistry Approach to Interpret the Crystal Violet Adsorption on Golbasi Lignite Activated Carbon

    NASA Astrophysics Data System (ADS)

    Depci, Tolga; Sarikaya, Musa; Prisbrey, Keith A.; Yucel, Aysegul

    2016-10-01

    In this paper, adsorption mechanism of Crystal Violet (CV) dye from the aqueous solution on the activated carbon prepared from Golbasi lignite was explained and interpreted by a computational chemistry approach and experimental studies. Molecular dynamic simulations and Ab initio frontier orbital analysis indicated relatively high energy and electron transfer processes during adsorption, and molecular dynamics simulations showed CV dye molecules moving around on the activated carbon surface after adsorption, facilitating penetration into cracks and pores. The experimental results supported to molecular dynamic simulation and showed that the monolayer coverage occurred on the activated carbon surface and each CV dye ion had equal sorption activation energy.

  8. Effects of microwave heating on porous structure of regenerated powdered activated carbon used in xylose.

    PubMed

    Li, Wei; Wang, Xinying; Peng, Jinhui

    2014-01-01

    The regeneration of spent powdered activated carbons used in xylose decolourization by microwave heating was investigated. Effects of microwave power and microwave heating time on the adsorption capacity of regenerated activated carbons were evaluated. The optimum conditions obtained are as follows: microwave power 800W; microwave heating time 30min. Regenerated activated carbon in this work has high adsorption capacities for the amount of methylene blue of 16 cm3/0.1 g and the iodine number of 1000.06mg/g. The specific surface areas of fresh commercial activated carbon, spent carbon and regenerated activated carbon were calculated according to the Brunauer, Emmett and Teller method, and the pore-size distributions of these carbons were characterized by non-local density functional theory (NLDFT). The results show that the specific surface area and the total pore volume of regenerated activated carbon are 1064 m2/g and 1.181 mL/g, respectively, indicating the feasibility of regeneration of spent powdered activated carbon used in xylose decolourization by microwave heating. The results of surface fractal dimensions also confirm the results of isotherms and NLDFT.

  9. Cooperative redox activation for carbon dioxide conversion

    NASA Astrophysics Data System (ADS)

    Lian, Zhong; Nielsen, Dennis U.; Lindhardt, Anders T.; Daasbjerg, Kim; Skrydstrup, Troels

    2016-12-01

    A longstanding challenge in production chemistry is the development of catalytic methods for the transformation of carbon dioxide into useful chemicals. Silane and borane promoted reductions can be fined-tuned to provide a number of C1-building blocks under mild conditions, but these approaches are limited because of the production of stoichiometric waste compounds. Here we report on the conversion of CO2 with diaryldisilanes, which through cooperative redox activation generate carbon monoxide and a diaryldisiloxane that actively participate in a palladium-catalysed carbonylative Hiyama-Denmark coupling for the synthesis of an array of pharmaceutically relevant diarylketones. Thus the disilane reagent not only serves as the oxygen abstracting agent from CO2, but the silicon-containing `waste', produced through oxygen insertion into the Si-Si bond, participates as a reagent for the transmetalation step in the carbonylative coupling. Hence this concept of cooperative redox activation opens up for new avenues in the conversion of CO2.

  10. Nanostructure modification to carbon nanowall surface employing hydrogen peroxide solution

    NASA Astrophysics Data System (ADS)

    Shimoeda, Hironao; Kondo, Hiroki; Ishikawa, Kenji; Hiramatsu, Mineo; Sekine, Makoto; Hori, Masaru

    2014-04-01

    Carbon nanowalls (CNWs), which are three-dimensional carbon nanomaterials consisting of stacks of graphene sheets vertically standing on substrates, possess a mazelike architecture containing high-density graphene edges and large-area plane surfaces. A selective morphological modification technique for the surfaces of CNWs after their growth has been developed employing hydrogen peroxide (H2O2) solution. It was found that oxidative radicals in H2O2 solution formed characteristic nanometer-scale asperities on the CNW surface without etching from the top edges. Photoelectron spectra indicate that hydroxyl adsorption and subsequent reactions at the edge and plane of graphene contribute to the selective morphological change on the CNW surface.

  11. Production and characterization of activated carbons from cereal grains

    SciTech Connect

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

    1996-10-01

    The kernels of grain such as corn and hard red winter wheat were subjected to a two-stage pyrolytic process to generate relatively high yields of charcoals. The process involved carbonization of the kernels at low temperatures (250-325{degrees}C) followed by complete devolatilization of the resultant charcoals at around 750{degrees}C. The charcoals were subsequently activated physically with CO{sub 2} at 800{degrees}C to yield activated carbons. The total pore volumes and surface areas of the activated carbons were determined at various degree of activation by physisorption methods. The surface areas from the nitrogen BET method ranged from 500 to 1750 m{sup 2}/g, while the total pore volumes obtained from the volumes at saturation were in the interval from 0.3 to 0.7 cm{sup 3}/g. The fractal nature of the pore interfaces as well as the existence of different types of pores were investigated through small-angle x-ray scattering.

  12. 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.

  13. Application of response surface methodology (RSM) for optimisation of COD, NH3-N and 2,4-DCP removal from recycled paper wastewater in a pilot-scale granular activated carbon sequencing batch biofilm reactor (GAC-SBBR).

    PubMed

    Muhamad, Mohd Hafizuddin; Sheikh Abdullah, Siti Rozaimah; Mohamad, Abu Bakar; Abdul Rahman, Rakmi; Hasan Kadhum, Abdul Amir

    2013-05-30

    In this study, the potential of a pilot-scale granular activated carbon sequencing batch biofilm reactor (GAC-SBBR) for removing chemical oxygen demand (COD), ammoniacal nitrogen (NH3-N) and 2,4-dichlorophenol (2,4-DCP) from recycled paper wastewater was assessed. For this purpose, the response surface methodology (RSM) was employed, using a central composite face-centred design (CCFD), to optimise three of the most important operating variables, i.e., hydraulic retention time (HRT), aeration rate (AR) and influent feed concentration (IFC), in the pilot-scale GAC-SBBR process for recycled paper wastewater treatment. Quadratic models were developed for the response variables, i.e., COD, NH3-N and 2,4-DCP removal, based on the high value (>0.9) of the coefficient of determination (R(2)) obtained from the analysis of variance (ANOVA). The optimal conditions were established at 750 mg COD/L IFC, 3.2 m(3)/min AR and 1 day HRT, corresponding to predicted COD, NH3-N and 2,4-DCP removal percentages of 94.8, 100 and 80.9%, respectively.

  14. Production of activated carbon from a new precursor molasses by activation with sulphuric acid.

    PubMed

    Legrouri, K; Khouya, E; Ezzine, M; Hannache, H; Denoyel, R; Pallier, R; Naslain, R

    2005-02-14

    Activated carbon has been prepared from molasses, a natural precursor of vegetable origin resulting from the sugar industry in Morocco. The preparation of the activated carbon from the molasses has been carried out by impregnation of the precursor with sulphuric acid, followed by carbonisation at varying conditions (temperature and gas coverage) in order to optimize preparation parameters. The influence of activation conditions was investigated by determination of adsorption capacity of methylene blue and iodine, the BET surface area, and the pore volume of the activated carbon were determined while the micropore volume was determined by the Dubinin-Radushkevich (DR) equation. The activated materials are mainly microporous and reveal the type I isotherm of the Brunauer classification for nitrogen adsorption. The activated carbons properties in this study were found for activation of the mixture (molasses/sulphuric acid) in steam at 750 degrees C. The samples obtained in this condition were highly microporous, with high surface area (> or =1200 m2/g) and the maximum adsorption capacity of methylene blue and iodine were 435 and 1430 mg/g, respectively.

  15. Pharmaceutical and biomedical applications of surface engineered carbon nanotubes.

    PubMed

    Mehra, Neelesh Kumar; Jain, Keerti; Jain, Narendra Kumar

    2015-06-01

    Surface engineered carbon nanotubes (CNTs) are attracting recent attention of scientists owing to their vivid biomedical and pharmaceutical applications. The focus of this review is to highlight the important role of surface engineered CNTs in the highly challenging but rewarding area of nanotechnology. The major strength of this review lies in highlighting the exciting applications of CNTs to boost the research efforts, which unfortunately are otherwise scattered in the literature making the reading non-coherent and non-homogeneous.

  16. 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.

  17. Following the Interstellar History of Carbon: From the Interiors of Stars to the Surfaces of Planets.

    PubMed

    Ziurys, L M; Halfen, D T; Geppert, W; Aikawa, Y

    2016-12-01

    The chemical history of carbon is traced from its origin in stellar nucleosynthesis to its delivery to planet surfaces. The molecular carriers of this element are examined at each stage in the cycling of interstellar organic material and their eventual incorporation into solar system bodies. The connection between the various interstellar carbon reservoirs is also examined. Carbon has two stellar sources: supernova explosions and mass loss from evolved stars. In the latter case, the carbon is dredged up from the interior and then ejected into a circumstellar envelope, where a rich and unusual C-based chemistry occurs. This molecular material is eventually released into the general interstellar medium through planetary nebulae. It is first incorporated into diffuse clouds, where carbon is found in polyatomic molecules such as H2CO, HCN, HNC, c-C3H2, and even C60(+). These objects then collapse into dense clouds, the sites of star and planet formation. Such clouds foster an active organic chemistry, producing compounds with a wide range of functional groups with both gas-phase and surface mechanisms. As stars and planets form, the chemical composition is altered by increasing stellar radiation, as well as possibly by reactions in the presolar nebula. Some molecular, carbon-rich material remains pristine, however, encapsulated in comets, meteorites, and interplanetary dust particles, and is delivered to planet surfaces. Key Words: Carbon isotopes-Prebiotic evolution-Interstellar molecules-Comets-Meteorites. Astrobiology 16, 997-1012.

  18. Investigation kinetics mechanisms of adsorption malachite green onto activated carbon.

    PubMed

    Onal, Y; Akmil-Başar, C; Sarici-Ozdemir, C

    2007-07-19

    Lignite was used to prepare activated carbon (T3K618) by chemical activation with KOH. Pore properties of the activated carbon such as BET surface area, pore volume, pore size distribution, and pore diameter were characterized by t-plot based on N2 adsorption isotherm. BET surface area of activated carbon is determined as 1000 m2/g. Adsorption capacity of malachite green (MG) onto T3K618 activated carbon was investigated in a batch system by considering the effects of various parameters like initial concentration (100, 150 and 200 mg/L) and temperature (25, 40 and 50 degrees C). The adsorption process was relatively fast and equilibrium was reached after about 20 min for 100, 150 mg/L at all adsorption temperature. Equilibrium time for 200 mg/L was determined as 20 min and 40 min at 298, 313 and 323 K, respectively. Simple mass and kinetic models were applied to the experimental data to examine the mechanisms of adsorption and potential rate controlling steps such as external mass transfer, intraparticle diffusion. Pseudo second-order model was found to explain the kinetics of MG adsorption most effectively. It was found that both mass transfer and pore diffusion are important in determining the adsorption rates. The intraparticle diffusion rate constant, external mass transfer coefficient, film and pore diffusion coefficient at various temperatures were evaluated. The activation energy (Ea) was determined as 48.56, 63.16, 67.93 kJ/mol for 100, 150, 200 mg/L, respectively. The Langmiur and Freundlich isotherm were used to describe the adsorption equilibrium studies at different temperatures. Langmiur isotherm shows better fit than Freundlich isotherm in the temperature range studied. The thermodynamic parameters, such as DeltaG degrees, DeltaS and DeltaH degrees were calculated. The thermodynamics of dyes-T3K618 system indicates endothermic process.

  19. Oil-containing waste water treating material consisting of modified active carbon

    SciTech Connect

    Sato, H.; Shigeta, S.; Takenaka, Y.

    1982-03-16

    An oil-containing waste water treating material comprises an active carbon upon whose surface is chemically bonded at least one nitrogenous compound which is an amine or a quaternarized derivative thereof.

  20. 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.

  1. CARBON SEQUESTRATION ON SURFACE MINE LANDS

    SciTech Connect

    Donald H. Graves; Christopher Barton; Richard Sweigard; Richard Warner

    2003-10-30

    The 2002-2003 Department of Energy plantings amounted to 164 acres containing 111,520 tree seedlings in eastern and western Kentucky. Data gathered on these trees included an inventory to determine survival of all planted species. A sub-sample of seedlings was selected to assess the height and diameter of individual species of seedlings established. Additional efforts involved collection of soil sample and litter samples, analysis of herbaceous ground cover from vegetation clip plots and leaf area on each tree species, and development of tissue collections. All areas were sampled for penetration resistance, penetration depth (or depth to refusal), and bulk density at various depths. Rain fall events and flow rates were recorded. The water quality of runoff samples involved the determination of total and settleable solids and particle size distribution. A study was initiated that will focus on the colonization of small mammals from forest edges to various areas located on reclaimed surface mines. This effort will provide a better understanding of the role small mammals and birds have in the establishment of plant communities on mine lands that will be useful in developing and improving reclamation techniques.

  2. Highly porous activated carbons from resource-recovered Leucaena leucocephala wood as capacitive deionization electrodes.

    PubMed

    Hou, Chia-Hung; Liu, Nei-Ling; Hsi, Hsing-Cheng

    2015-12-01

    Highly porous activated carbons were resource-recovered from Leucaena leucocephala (Lam.) de Wit. wood through combined chemical and physical activation (i.e., KOH etching followed by CO2 activation). This invasive species, which has severely damaged the ecological economics of Taiwan, was used as the precursor for producing high-quality carbonaceous electrodes for capacitive deionization (CDI). Carbonization and activation conditions strongly influenced the structure of chars and activated carbons. The total surface area and pore volume of activated carbons increased with increasing KOH/char ratio and activation time. Overgasification induced a substantial amount of mesopores in the activated carbons. In addition, the electrochemical properties and CDI electrosorptive performance of the activated carbons were evaluated; cyclic voltammetry and galvanostatic charge/discharge measurements revealed a typical capacitive behavior and electrical double layer formation, confirming ion electrosorption in the porous structure. The activated-carbon electrode, which possessed high surface area and both mesopores and micropores, exhibited improved capacitor characteristics and high electrosorptive performance. Highly porous activated carbons derived from waste L. leucocephala were demonstrated to be suitable CDI electrode materials.

  3. Effect of nanoporous carbon surface chemistry on the removal of endocrine disruptors from water phase.

    PubMed

    Vidal, Carla B; Seredych, Mykola; Rodríguez-Castellón, Enrique; Nascimento, Ronaldo F; Bandosz, Teresa J

    2015-07-01

    Wood-based activated carbon and its sulfur-doped counterpart were used as adsorbents of endocrine disruptor chemicals (EDC) from aqueous solution. Adsorption process was carried out in dynamic conditions and Thomas model was used to predict the performance of the column. The results showed a good fitting of the theoretical curve to the experimental data. S-doped carbon exhibited a higher adsorption capacity of trimethoprim (TMP) and smaller of sulfamethoxazole (SMX) and diclofenac (DCF) in comparison with the carbon with no sulfur incorporated into the matrix. The surface features of the initial carbons and those exposed to EDC were evaluated in order to derive the adsorption mechanism and elucidate the role of surface features. An increase in the amount of TMP from a low concentration solution (10 mg/L) on sulfur-doped carbon was linked to acid-base interactions and the reactive adsorption/oxidation of TMP. A decrease in SMX and DCF after sulfur doping was explained by a considerable increase in surface hydrophobicity, which does not favor the retention of polar DCF and SMX molecules. When the adsorption was measured from a high concentration solution at equilibrium conditions at the dark or under solar light irradiation different trends in the adsorption capacities were found. This was linked to the photoactivity of carbons and the degradation of EDC in the pore system promoted by visible light followed by the adsorption of the products of surface reactions.

  4. Carbon surface conditioning produces an anode suitable for heavy-duty discharge in Li secondary batteries

    SciTech Connect

    Takamura, Tsutomu; Kikuchi, Masahiro; Awano, Hidekazu; Ura, Tetsuya; Ikezawa, Yasunari

    1995-12-31

    Carbon fibers prepared at 1,000 C from mesophase pitch were treated with trimethyl silazane for modifying surface -OH group into trimethyl silyl group. The irreversible reduction current on the first cathodic sweep was diminished. Low-temperature carbon fibers prepared at 700 C and active carbon fibers were evaluated for electrochemical lithium doping and undoping reaction in propylene carbonate (PC)/ethylene carbonate or PC/dimethyl carbonate mixtures (1:1) containing 1 M LiClO{sub 4} at room temperature. Pristine samples prepared at 700 C gave very poor reversibility and capacity on cyclic voltammograms(cv), but a constant current charge/discharge with a very low current gave a capacity over 400 mAh/g. After prolonged heating at 700 C, the cv characteristics were gradually improved. Partial oxidation in a mild oxidizing atmosphere at 700 C for a few minutes was found to be quite effective in improving the cv characteristics remarkably. The charge/discharge capacity, however, was very similar to that obtained for the pristine sample at a very low constant current. Active carbon fibers were found to have considerable capacity after repeated oxidation/reduction cycles in solution. Partial oxidation treatment was also effective in increasing the charge/discharge current. The improvement due to the heat treatment is elucidated based on the removal of a surface inhibiting layer through the treatment.

  5. Transforming hair into heteroatom-doped carbon with high surface area.

    PubMed

    Chaudhari, Kiran N; Song, Min Young; Yu, Jong-Sung

    2014-07-09

    Herein, a unique approach to dispose of human hair by pyrolizing it in a regulated environment is presented, yielding highly porous, conductive hair carbons with heteroatoms and high surface area. α-keratin in the protein network of hair serves as a precursor for the heteroatoms and carbon. The carbon framework is ingrained with heteroatoms such as nitrogen and sulfur, which otherwise are incorporated externally through energy-intensive, hazardous, chemical reactions using proper organic precursors. This judicious transformation of organic-rich waste not only addresses the disposal issue, but also generates valuable functional carbon materials from the discard. This unique synthesis strategy involving moderate activation and further graphitization enhances the electrical conductivity, while still maintaining the precious heteroatoms. The effect of temperature on the structural and functional properties is studied, and all the as-obtained carbons are applied as metal-free catalysts for the oxygen reduction reaction (ORR). Carbon graphitized at 900 °C emerges as a superior ORR electrocatalyst with excellent electrocatalytic performance, high selectivity, and long durability, demonstrating that hair carbon can be a promising alternative for costly Pt-based electrocatalysts in fuel cells. The ORR performance can be discussed in terms of heteroatom doping, surface properties, and electrical conductivity of the resulting porous hair carbon materials.

  6. Migration of Carbon Adatoms on the Surface of Charged SWCNT

    NASA Astrophysics Data System (ADS)

    Han, Longtao; Krstic, Predrag; Kaganovich, Igor

    2016-10-01

    In volume plasma, the growth of SWCNT from a transition metal catalyst could be enhanced by incoming carbon flux on SWCNT surface, which is generated by the adsorption and migration of carbon adatoms on SWCNT surface. In addition, the nanotube can be charged by the irradiation of plasma particles. How this charging effect will influence the adsorption and migration behavior of carbon atom has not been revealed. Using Density Functional Theory, Nudged Elastic Band and Kinetic Monte Carlo method, we found equilibrium sites, vibrational frequency, adsorption energy, most probable pathways for migration of adatoms, and the barrier sizes along these pathways. The metallic (5,5) SWCNT can support a fast migration of the carbon adatom along a straight path with low barriers, which is further enhanced by the presence of negative charge on SWCNT. The enhancement is contributed by the higher adsorption energy and thence longer lifetime of adatom on the charged SWCNT surface. The lifetime and migration distance of adatom increase by three and two orders of magnitude, respectively, as shown by Kinetic Monte Carlo simulation. These results support the surface migration mechanism of SWCNT growth in plasma environment. This work was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Material Sciences and Engineering Division.

  7. Activated carbons prepared from refuse derived fuel and their gold adsorption characteristics.

    PubMed

    Buah, William K; Williams, Paul T

    2010-02-01

    Activated carbons produced from refuse derived fuel (RDF), which had been prepared from municipal solid waste have been characterized and evaluated for their potential for gold adsorption from gold chloride solution. Pyrolysis of the RDF produced a char, which was then activated via steam gasification to produce activated carbons. Steam gasification of the char at 900 degrees C for 3 h yielded 73 wt% activated carbon. The derived activated carbon had a surface area of 500 m2 g(-1) and a total pore volume of 0.19 cm3 g(-1). The gold adsorption capacity of the activated carbon was 32.1 mg Au g(-1) of carbon when contacted with an acidified gold chloride solution. The gold adsorption capacity was comparable to that of a commercial activated carbon tested under the same conditions and was well in the range of values of activated carbons used in the gold industry. Demineralization of the RDF activated carbon in a 5 M HCl solution resulted in enhancement of its textural properties but a reduction in the gold adsorption rate, indicating that the metal content of the RDF activated carbon influenced its gold adsorption rate.

  8. Bioactive carbon-PEEK composites prepared by chemical surface treatment.

    PubMed

    Miyazaki, Toshiki; Matsunami, Chisato; Shirosaki, Yuki

    2017-01-01

    Polyetheretherketone (PEEK) has attracted much attention as an artificial intervertebral spacer for spinal reconstruction. Furthermore, PEEK plastic reinforced with carbon fiber has twice the bending strength of pure PEEK. However, the PEEK-based materials do not show ability for direct bone bonding, i.e., bioactivity. Although several trials have been conducted for enabling PEEK with bioactivity, few studies have reported on bioactive surface modification of carbon-PEEK composites. In the present study, we attempted the preparation of bioactive carbon-PEEK composites by chemical treatments with H2SO4 and CaCl2. Bioactivity was evaluated by in vitro apatite formation in simulated body fluid (SBF). The apatite formation on the carbon-PEEK composite was compared with that of pure PEEK. Both pure PEEK and carbon-PEEK composite formed the apatite in SBF when they were treated with H2SO4 and CaCl2; the latter showed higher apatite-forming ability than the former. It is conjectured that many functional groups able to induce the apatite nucleation, such as sulfo and carboxyl groups, are incorporated into the dispersed carbon phase in the carbon-PEEK composites.

  9. Optimization of microporous palm shell activated carbon production for flue gas desulphurization: experimental and statistical studies.

    PubMed

    Sumathi, S; Bhatia, S; Lee, K T; Mohamed, A R

    2009-02-01

    Optimizing the production of microporous activated carbon from waste palm shell was done by applying experimental design methodology. The product, palm shell activated carbon was tested for removal of SO2 gas from flue gas. The activated carbon production was mathematically described as a function of parameters such as flow rate, activation time and activation temperature of carbonization. These parameters were modeled using response surface methodology. The experiments were carried out as a central composite design consisting of 32 experiments. Quadratic models were developed for surface area, total pore volume, and microporosity in term of micropore fraction. The models were used to obtain the optimum process condition for the production of microporous palm shell activated carbon useful for SO2 removal. The optimized palm shell activated carbon with surface area of 973 m(2)/g, total pore volume of 0.78 cc/g and micropore fraction of 70.5% showed an excellent agreement with the amount predicted by the statistical analysis. Palm shell activated carbon with higher surface area and microporosity fraction showed good adsorption affinity for SO2 removal.

  10. The reaction of carbon dioxide with amines at a Cu(211) surface

    NASA Astrophysics Data System (ADS)

    Davies, Philip R.; Keel, James M.

    2000-12-01

    The activation of carbon dioxide by different amines has been studied at 80 K at clean Cu(211) surfaces using X-ray photoelectron spectroscopy (XPS). Three amines were investigated: monomethylamine (CH 3NH 2), dimethylamine [(CH 3) 2NH] and ethylamine (CH 3CH 2NH 2). All three physisorb at the clean surface at 80 K with characteristic N(1s) and C(1s) binding energies in the range 400.0-400.5 eV and 286.8-286.3 eV, respectively. The amines are more strongly bound to the surface than ammonia, desorbing molecularly between 250 and 290 K, whereas ammonia desorbs from copper surfaces at about 170-190 K. The extra stability of the amines is attributed to a greater interaction between the surface and the nitrogen lone pair. Carbon dioxide physisorbs at clean Cu(211) surfaces and desorbs by 130 K, but when coadsorbed with the amines, XPS spectra show high concentrations of an oxygen-, carbon- and nitrogen-containing species to temperatures above 450 K. On the basis of the N:O:C stoichiometries, the thermal stability of the species and the binding energies of the associated XPS peaks, the products of the amine-carbon dioxide interactions are assigned to carbamates [RR'NCO 2(a)]. On heating, the carbamates desorb leaving no decomposition products at the surface.

  11. Wettability on Inner and Outer Surface of Single Carbon Nanotubes.

    PubMed

    Yamada, Yutaka; Takahashi, Koji; Takata, Yasuyuki; Sefiane, Khellil

    2016-07-19

    The surface wettability of a liquid on the inner and outer surface of single carbon nanotubes (CNTs) was experimentally investigated. Although these contact angles on both surfaces were previously studied separately, the available data are of limited help to elucidate the effect of curvature orientation (concave or convex) on wettability due to the difference in surface structure. Here, we report on the three-phase contact region and wettability on the outer surface of CNT during the dipping and withdrawing experiment of CNT into an ionic liquid. Furthermore, the wettability on the inner surface was measured using a liquid within the same CNT. Our results show that the contact angle on the outer surface of the CNT is larger than that on the flat surface and that on the inner surface is smaller than that on the flat one. These findings suggest that the surface curvature orientation has a noticeable effect on the contact angle at the nanoscale because both inner and outer surfaces expose the same graphite wall structure and the contact line tension will be negligible in this situation. The presented results are rationalized using the free energy balance of liquid on curved surfaces.

  12. 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.

  13. Structural and electronic properties of a tetrahedral amorphous carbon surface

    NASA Astrophysics Data System (ADS)

    Dong, Jianjun; Drabold, D. A.

    1997-03-01

    We present ab initio studies of a model of tetrahedral amorphous carbon (ta-C) surface. Our methodology is LDA (with Harris functional and local basis) molecular dynamics simulations. The surface is modeled by a 216 atom slab supercell. Several candidate slabs are constructed by starting with the DTW model (B.R. Djordjevic, M.F. Thorpe and F. Wooten, Phys. Rev. B 52) 5685 (1995) and applying various simulated heating/quenching cycles. We analyze the structural and electronic properties of the surface , with special attention forcused on the electronic signatures of surface structural defects. Preliminary results indicate that the surface layer significantly graphitizes, and many surface gap states are present in the electronic density of states.

  14. Characterization and restoration of performance of {open_quotes}aged{close_quotes} radioiodine removing activated carbons

    SciTech Connect

    Freeman, W.P.

    1997-08-01

    The degradation of radioiodine removal performance for impregnated activated carbons because of ageing is well established. However, the causes for this degradation remain unclear. One theory is that this reduction in performance from the ageing process results from an oxidation of the surface of the carbon. Radioiodine removing activated carbons that failed radioiodine removal tests showed an oxidized surface that had become hydrophilic compared with new carbons. We attempted to restore the performance of these {open_quotes}failed{close_quotes} carbons with a combination of thermal and chemical treatment. The results of these investigations are presented and discussed with the view of extending the life of radioiodine removing activated carbons. 4 refs., 2 tabs.

  15. Catechol-modified activated carbon prepared by the diazonium chemistry for application as active electrode material in electrochemical capacitor.

    PubMed

    Pognon, Grégory; Cougnon, Charles; Mayilukila, Dilungane; Bélanger, Daniel

    2012-08-01

    Activated carbon (Black Pearls 2000) modified with electroactive catechol groups was evaluated for charge storage application as active composite electrode material in an aqueous electrochemical capacitor. High surface area Black Pearls 2000 carbon was functionalized by introduction of catechol groups by spontaneous reduction of catechol diazonium ions in situ prepared in aqueous solution from the corresponding amine. Change in the specific surface area and pore texture of the carbon following grafting was monitored by nitrogen gas adsorption measurements. The electrochemical properties and the chemical composition of the catechol-modified carbon electrodes were investigated by cyclic voltammetry. Such carbon-modified electrode combines well the faradaic capacitance, originating from the redox activity of the surface immobilized catechol groups, to the electrochemical double layer capacitance of the high surface area Black Pearls carbon. Due to the faradaic contribution, the catechol-modified electrode exhibits a higher specific capacitance (250 F/g) than pristine carbon (150 F/g) over a potential range of -0.4 to 0.75 V in 1 M H(2)SO(4). The stability of the modified electrode evaluated by long-time charge/discharge cycling revealed a low decrease of the capacitance of the catechol-modified carbon due to the loss of the catechol redox activity. Nonetheless, it was demonstrated that the benefit of redox groups persists for 10, 000 constant current charge/discharge cycles.

  16. Effects of Surface Oxygen on the Performance of Carbon as an Anode in Lithium-Ion Batteries

    NASA Technical Reports Server (NTRS)

    Hung, Ching-Cheh; Clark, Gregory W.

    2001-01-01

    Carbon materials with similar bulk structure but different surface oxygen were compared for their performance as anodes in lithium-ion battery. The bulk structure was such that the graphene planes were perpendicular to the surface. Three types of surfaces were examined: surface containing C=O type oxygen. surface containing -O-C type oxygen, and surface containing high concentration of active sites. The test involved cycles of lithium insertion into and release from the carbon materials, which was in the half cells of carbon/saturated LiI-50/50 (vol %) EC and DMC/lithium. During the first cycle of lithium insertion, the presence of adsorbed oxygen, -O-C type oxygen, active carbon sites, and C=O type oxygen resulted in the formation of solid-electrolyte interface (SEI) when the carbon's voltage relative to lithium metal was >1.35, 1 to 1.35, 0.5 to 1, and 0.67 to 0.7 V, respectively. An optimum -O-C type oxygen and a minimum C=O type oxygen was found to increase the reversible and decrease the irreversible capacity of carbon. Active sites on the carbon surface result in a large irreversible capacity and a second lithium insertion-release mechanism. However, this new mechanism has a short cycle life.

  17. [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.

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

    PubMed

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

    2006-08-25

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

  19. Small Si clusters on surfaces of carbon nanotubes

    SciTech Connect

    Meng, Lijun; Zhang, Kaiwang; Stocks, George Malcolm; Zhong, Jianxin

    2006-01-01

    Structures of small Si clusters, Sin, on surfaces of carbon nanotubes have been studied by molecular dynamics simulation. We show that the lowest-energy structures of Sin are three-dimensional clusters rather than thin Si sheets covering the surface of a nanotube. As n increases from 10 to 30, Sin undergoes structural transitions from a tent-like structure (with nanotube surface as its base) to a cage-like structure (without interior atoms) and further to a spherical compact structure (with interior atoms). Our results are different from the structures of small Si clusters found in a free space without Si-nanotube interaction.

  20. Simulation of the Thermographic Response of Near Surface Flaws in Reinforced Carbon-Carbon Panels

    NASA Technical Reports Server (NTRS)

    Winfree, William P.; Howell, Patricia A.; Burke, Eric R.

    2009-01-01

    Thermographic inspection is a viable technique for detecting in-service damage in reinforced carbon-carbon (RCC) composites that are used for thermal protection in the leading edge of the shuttle orbiter. A thermographic technique for detection of near surface flaws in RCC composite structures is presented. A finite element model of the heat diffusion in structures with expected flaw configurations is in good agreement with the experimental measurements.

  1. SIMULATIONS OF THE THERMOGRAPHIC RESPONSE OF NEAR SURFACE FLAWS IN REINFORCED CARBON-CARBON PANELS

    SciTech Connect

    Winfree, William P.; Howell, Patricia A.; Burke, Eric R.

    2010-02-22

    Thermographic inspection is a viable technique for detecting in-service damage in reinforced carbon-carbon (RCC) composites that are used for thermal protection in the leading edge of the shuttle orbiter. A thermographic technique for detection of near surface flaws in RCC composite structures is presented. A finite element model of the heat diffusion in structures with expected flaw configurations is in good agreement with the experimental measurements.

  2. Grafting the surface of carbon nanotubes and carbon black with the chemical properties of hyperbranched polyamines

    PubMed Central

    Morales-Lara, Francisco; Domingo-García, María; López-Garzón, Rafael; Luz Godino-Salido, María; Peñas-Sanjuán, Antonio; López-Garzón, F. Javier; Pérez-Mendoza, Manuel; Melguizo, Manuel

    2016-01-01

    Abstract Controlling the chemistry on the surface of new carbon materials is a key factor to widen the range of their applicability. In this paper we show a grafting methodology of polyalkylamines to the surface of carbon nanomaterials, in particular, carbon nanotubes and a carbon black. The aim of this work is to reach large degrees of covalent functionalization with hyperbranched polyethyleneimines (HBPEIs) and to efficiently preserve the strong chelating properties of the HBPEIs when they are fixed to the surface of these carbon materials. This functionalization opens new possibilities of using these carbon nanotubes-based hybrids. The results show that the HBPEIs are covalently attached to the carbon materials, forming hybrids. These hybrids emerge from the reaction of amine functions of the HBPEIs with carbonyls and carboxylic anhydrides of the carbon surface which become imine and imide bonds. Thus, due to the nature of these bonds, the pre-oxidized samples with relevant number of C=O groups showed an increase in the degree of functionalization with the HBPEIs. Furthermore, both the acid-base properties and the coordination capacity for metal ions of the hybrids are equivalent to that of the free HBPEIs in solution. This means that the chemical characteristics of the HBPEIs have been efficiently transferred to the hybrids. To reach this conclusion we have developed a novel procedure to assess the acid-base and the coordination properties of the hybrids (solids) by means of potentiometric titration. The good agreement of the values obtained for the hybrids and for the free HBPEIs in aqueous solution supports the reliability of the procedure. Moreover, the high capacity of the hybrids to capture Ni2+ by complexation opens new possibilities of using these hybrids to capture high-value metal ions such as Pd2+ and Pt2+. PMID:27877902

  3. [Hydrogen induced C-C, C-N, and C-S bond activities on Pi and Ni surfaces]: Summary

    SciTech Connect

    Gland, J.L.

    1994-12-31

    This document summarizes research applied to chemical bond activation studies. Topics summarized include: Carbon nitrogen bonds experimentation with aniline on Ni(111), Mi(100), and Pt(111) surfaces; carbon sulfur bonds experimentation with methanethiol, phenylthiol, and dimethyl disulfide on Pt(111) and Ni(111) surfaces; carbon-carbon bonds experimentation on Ni(100), Ni(111) and Pt(111) surfaces; and in-situ fluorescence yield near edge spectroscopy.

  4. Tuning the surface wettability of carbon nanotube carpets in multiscale hierarchical solids

    NASA Astrophysics Data System (ADS)

    Karumuri, Anil K.; He, Lvmeng; Mukhopadhyay, Sharmila M.

    2015-02-01

    An attractive approach of increasing functionality of solid surfaces is to create hierarchical multiscale morphology by attaching tailored carpet-like arrays of Carbon nanotubes (CNT) on them. Such surfaces offer fractal morphology along with unprecedented increase in specific surface areas, and significantly boost the potency of porous materials used in surface-active applications. However, full utilization of these structures will require intimate interaction between the solid surface and its environmental fluid. CNT arrays tend to be hydrophobic, which limit their effectiveness in aqueous environments. In this research, we investigated two different surface modifications methods to induce hydrophilic property to CNT nano-carpets on graphitic substrates: dry oxygen plasma treatment and wet sol-gel oxide coating. Structure, morphology, composition and chemistry of these multiscale surfaces have been related to wettability and water flow properties. Plasma oxygen treatments did not alter the surface morphology, but induced temporary wettability, that could be reversed by heat treatment. On the other hand, sol-gel treatment permanently coated the nanotubes with a strongly bonded layer of amorphous SiO2. This coating imparts permanent alterations in surface chemistry, contact angle, wettability and water flow. Porous carbon foams were coated with CNT arrays and their water permeability measured before and after sol-gel silica coating. The hydrophilic coating was seen to increase flow rate and reduce pressure build-up. These results have important implications on all devices that utilize surface activity of porous solids, such as catalytic membranes, antimicrobial filters, and microfluidic sensors.

  5. Granular activated carbons from broiler manure: physical, chemical and adsorptive properties.

    PubMed

    Lima, Isabel M; Marshall, Wayne E

    2005-04-01

    Broiler manure produced at large concentrated facilities poses risks to the quality of water and public health. This study utilizes broiler litter and cake as source materials for granular activated carbon production and optimizes conditions for their production. Pelletized manure samples were pyrolyzed at 700 degrees C for 1 h followed by activation in an inert atmosphere under steam at different water flow rates, for a period ranging from 15 to 75 min. Carbon physical and adsorptive properties were dependent on activation time and quantity of steam used as activant, yields varied from 18% to 28%, surface area varied from 253 to 548 m2/g and copper ion adsorption varied from 0.13 to 1.92 mmol Cu2+/g carbon. Best overall performing carbons were steam activated for 45 min at 3 ml/min. Comparative studies with commercial carbons revealed the broiler cake-based carbon as having the highest copper ion efficiency.

  6. Preparation of activated carbons from raw and biotreated agricultural residues for removal of volatile organic compounds.

    PubMed

    Hsi, Hsing-Cheng; Horng, Richard S; Pan, Tai-An; Lee, Shin-Ku

    2011-05-01

    Activated carbons with diverse physical and chemical properties were produced from four agriculture residues, including raw barley husk, biotreated barley husk, rice husk, and pistachio shell. Results showed that with adequate steam activation (30-90 min, 50% H2O(g),/50% N2), activated carbons with surface areas between 360 and 950 m2 g(-1) were developed. Further increases in the activation time destroyed the pore structure of activated carbons, which resulted in a decrease in the surface area and pore volume. Biotreated agricultural residues were found to be suitable precursors for producing mesoporous activated carbons. The oxygen content of activated carbons increased with increasing activation time. Results from X-ray photoelectron spectroscopy examination further suggested that H2O molecules react with the carbon surface, enhancing the deconvoluted peak area of carbonyl and carboxyl groups. Equilibrium adsorption of toluene indicated that the adsorption capacities increased with an increase in the inlet toluene concentration and a decrease in temperature. The adsorption isotherms were successfully fitted with Freundlich, Langmuir, and Dubinin-Radushkevich equations. Activated carbons derived from agricultural residues appear to be more applicable to adsorb volatile organic compounds at a low concentration and high-temperature environment.

  7. 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.

  8. Carbon Nanotubes Covalently Attached to Functionalized Surfaces Directly through the Carbon Cage.

    PubMed

    Williams, Mackenzie G; Gao, Fei; BenDhiab, Ibtihel; Teplyakov, Andrew

    2017-02-07

    The covalent attachment of nonfunctionalized and carboxylic acid-functionalized carbon nanotubes to amine-terminated organic monolayers on gold and silicon surfaces is investigated. It is well established that the condensation reaction between a carboxylic acid and an amine is a viable method to anchor carbon nanotubes to solid substrates. The work presented here shows that the presence of the carboxylic group on the nanotube is not required for attachment to occur, as direct attachment via the substrate amine and the nanotube cage can take place. Scanning and transmission electron microscopy and atomic force microscopy confirm the presence of carbon nanotubes in intimate contact with the surface. X-ray photoelectron spectroscopy is utilized to compare the surface chemistry of the functionalized and nonfunctionalized carbon nanotubes and is supported by a computational investigation. Ion fragments attributed to the direct attachment between the surface and carbon nanotube cage are detected by time-of-flight secondary ion mass spectrometry. The overall attachment scheme is evaluated and can be further used on multiple carbonaceous materials attached to solid substrates.

  9. Structure and Surface Characterizations of High Strength Carbon Fibers.

    DTIC Science & Technology

    1987-09-01

    g) The ratio of the 100 peak area to the total diffraction area ( h ) The ratio between the 100 and 002 peak areas (i) Crystallinity index (from a...carbon linkages on the surface. These data are derived from the deconvolution of the C l5 peak into two 7 components: the carbons in C-C, C=C and C- H ...AMSTA-UL, Technical Library I AMSTA-R Commander, Army Research Office, P.O. Box 12211, Research 1 AMSTA-NS, Dr. H . H . Dobbs Triangle Park, NC 27709-2211 1

  10. Effect of activator on the structure and desulphurization efficiency of sludge-activated carbon.

    PubMed

    Li, Fen; Yan, Bo; Zhang, Yanping; Zhang, Linhuan; Lei, Tao

    2014-01-01

    Sludge-activated carbons (SACs) prepared with excess of activated sludge are used to solve the problems of sludge disposal and odour pollution in a sewage treatment plant. For the preparation, ZnCl2, KOH and H2SO4 are used as activators, respectively. The structure of the SACs are characterized by scanning electron microscope, X-ray photoelectron spectrometer, specific surface area and pore structure technologies, and the adsorption performance of H2S is investigated. Results indicate that the desulphurization activity of SACs, whose activators are ZnCl2 and KOH (SACZ and SACK), is better than that of carbon with H2SO4 as the activator (SACH). The breakthrough time of SACZ and SACK is up to 86 min, the sulphur capacity is 7.7 mg/cm3, and the maximal iodine value is 409.95 mg/g. While the breakthrough time of SACH is only 26 min with the sulphur capacity of 2.3 mg/cm3. A large percentage of pore volume with a diameter of 2-5 nm in the total pore volume is conductive to the desulphurization reaction. The large amount of surface acid functional groups is also helpful to the adsorption of H2S. The desulphurization activity of SACZ and SACK is superior over that of commercial-activated carbon.

  11. 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.

  12. 78 FR 13894 - Certain Activated Carbon From China

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-01

    ... COMMISSION Certain Activated Carbon From China Determination On the basis of the record \\1\\ developed in the... antidumping duty order on certain activated carbon from China would be likely to lead to continuation or... USITC Publication 4381 (February 2013), entitled Certain Activated Carbon from China: Investigation...

  13. Activated carbons from potato peels: The role of activation agent and carbonization temperature of biomass on their use as sorbents for bisphenol A uptake from aqueous solutions

    NASA Astrophysics Data System (ADS)

    Arampatzidou, An; Deliyanni, Eleni A.

    2015-04-01

    Activated carbons prepared from potato peels, a solid waste by product, and activated with different activating chemicals, have been studied for the adsorption of an endocrine disruptor (Bisphenol-A) from aqueous solutions. The potato peels biomass was activated with phosphoric acid, KOH and ZnCl2. The different activating chemicals were tested in order the better activation agent to be found. The carbons were carbonized by pyrolysis, in one step procedure, at three different temperatures in order the role of the temperature of carbonization to be pointed out. The porous texture and the surface chemistry of the prepared activated carbons were characterized by Nitrogen adsorption (BET), Scanning Electron Microscope (SEM), thermal analysis (DTA) and Fourier Transform Infrared Spectroscopy (FTIR). Batch experiments were performed to investigate the effect of pH, the adsorbent dose, the initial bisphenol A concentration and temperature. Equilibrium adsorption data were analyzed by Langmuir and Freundlich isotherms. The thermodynamic parameters such as the change of enthalpy (ΔH0), entropy (ΔS0) and Gibb's free energy (ΔG0) of adsorption systems were also evaluated. The adsorption capacity calculated from the Langmuir isotherm was found to be 450 mg g-1 at an initial pH 3 at 25 °C for the phosphoric acid activated carbon, that make the activated carbon a promising adsorbent material.

  14. Removal of carbon contaminations by RF plasma generated reactive species and subsequent effects on optical surface

    SciTech Connect

    Yadav, P. K. Rai, S. K.; Modi, M. H.; Nayak, M.; Lodha, G. S.; Kumar, M.; Chakera, J. A.; Naik, P. A.

    2015-06-24

    Carbon contamination on optical elements is a serious issue in synchrotron beam lines for several decades. The basic mechanism of carbon deposition on optics and cleaning strategies are not fully understood. Carbon growth mechanism and optimized cleaning procedures are worldwide under development stage. Optimized RF plasma cleaning is considered an active remedy for the same. In present study carbon contaminated optical test surfaces (carbon capped tungsten thin film) are exposed for 30 minutes to four different gases, rf plasma at constant power and constant dynamic pressure. Structural characterization (thickness, roughness and density) of virgin samples and plasma exposed samples was done by soft x-ray (λ=80 Å) reflectivity measurements at Indus-1 reflectivity beam line. Different gas plasma removes carbon with different rate (0.4 to 0.65 nm /min). A thin layer 2 to 9 nm of different roughness and density is observed at the top surface of tungsten film. Ar gas plasma is found more suitable for cleaning of tungsten surface.

  15. Following the Interstellar History of Carbon: From the Interiors of Stars to the Surfaces of Planets

    NASA Astrophysics Data System (ADS)

    Ziurys, L. M.; Halfen, D. T.; Geppert, W.; Aikawa, Y.

    2016-12-01

    The chemical history of carbon is traced from its origin in stellar nucleosynthesis to its delivery to planet surfaces. The molecular carriers of this element are examined at each stage in the cycling of interstellar organic material and their eventual incorporation into solar system bodies. The connection between the various interstellar carbon reservoirs is also examined. Carbon has two stellar sources: supernova explosions and mass loss from evolved stars. In the latter case, the carbon is dredged up from the interior and then ejected into a circumstellar envelope, where a rich and unusual C-based chemistry occurs. This molecular material is eventually released into the general interstellar medium through planetary nebulae. It is first incorporated into diffuse clouds, where carbon is found in polyatomic molecules such as H2CO, HCN, HNC, c-C3H2, and even C60+. These objects then collapse into dense clouds, the sites of star and planet formation. Such clouds foster an active organic chemistry, producing compounds with a wide range of functional groups with both gas-phase and surface mechanisms. As stars and planets form, the chemical composition is altered by increasing stellar radiation, as well as possibly by reactions in the presolar nebula. Some molecular, carbon-rich material remains pristine, however, encapsulated in comets, meteorites, and interplanetary dust particles, and is delivered to planet surfaces.

  16. Carbon Monoxide Dehydrogenase Activity in Bradyrhizobium japonicum

    PubMed Central

    Lorite, María J.; Tachil, Jörg; Sanjuán, Juán; Meyer, Ortwin; Bedmar, Eulogio J.

    2000-01-01

    Bradyrhizobium japonicum strain 110spc4 was capable of chemolithoautotrophic growth with carbon monoxide (CO) as a sole energy and carbon source under aerobic conditions. The enzyme carbon monoxide dehydrogenase (CODH; EC 1.2.99.2) has been purified 21-fold, with a yield of 16% and a specific activity of 58 nmol of CO oxidized/min/mg of protein, by a procedure that involved differential ultracentrifugation, anion-exchange chromatography, hydrophobic interaction chromatography, and gel filtration. The purified enzyme gave a single protein and activity band on nondenaturing polyacrylamide gel electrophoresis and had a molecular mass of 230,000 Da. The 230-kDa enzyme was composed of large (L; 75-kDa), medium (M; 28.4-kDa), and small (S; 17.2-kDa) subunits occurring in heterohexameric (LMS)2 subunit composition. The 75-kDa polypeptide exhibited immunological cross-reactivity with the large subunit of the CODH of Oligotropha carboxidovorans. The B. japonicum enzyme contained, per mole, 2.29 atoms of Mo, 7.96 atoms of Fe, 7.60 atoms of labile S, and 1.99 mol of flavin. Treatment of the enzyme with iodoacetamide yielded di(carboxamidomethyl)molybdopterin cytosine dinucleotide, identifying molybdopterin cytosine dinucleotide as the organic portion of the B. japonicum CODH molybdenum cofactor. The absorption spectrum of the purified enzyme was characteristic of a molybdenum-containing iron-sulfur flavoprotein. PMID:10788353

  17. Carbon monoxide dehydrogenase activity in Bradyrhizobium japonicum.

    PubMed

    Lorite, M J; Tachil, J; Sanjuán, J; Meyer, O; Bedmar, E J

    2000-05-01

    Bradyrhizobium japonicum strain 110spc4 was capable of chemolithoautotrophic growth with carbon monoxide (CO) as a sole energy and carbon source under aerobic conditions. The enzyme carbon monoxide dehydrogenase (CODH; EC 1.2.99.2) has been purified 21-fold, with a yield of 16% and a specific activity of 58 nmol of CO oxidized/min/mg of protein, by a procedure that involved differential ultracentrifugation, anion-exchange chromatography, hydrophobic interaction chromatography, and gel filtration. The purified enzyme gave a single protein and activity band on nondenaturing polyacrylamide gel electrophoresis and had a molecular mass of 230,000 Da. The 230-kDa enzyme was composed of large (L; 75-kDa), medium (M; 28.4-kDa), and small (S; 17.2-kDa) subunits occurring in heterohexameric (LMS)(2) subunit composition. The 75-kDa polypeptide exhibited immunological cross-reactivity with the large subunit of the CODH of Oligotropha carboxidovorans. The B. japonicum enzyme contained, per mole, 2.29 atoms of Mo, 7.96 atoms of Fe, 7.60 atoms of labile S, and 1.99 mol of flavin. Treatment of the enzyme with iodoacetamide yielded di(carboxamidomethyl)molybdopterin cytosine dinucleotide, identifying molybdopterin cytosine dinucleotide as the organic portion of the B. japonicum CODH molybdenum cofactor. The absorption spectrum of the purified enzyme was characteristic of a molybdenum-containing iron-sulfur flavoprotein.

  18. Anthropogenic carbon in the ocean—Surface to interior connections

    NASA Astrophysics Data System (ADS)

    Groeskamp, Sjoerd; Lenton, Andrew; Matear, Richard; Sloyan, Bernadette M.; Langlais, Clothilde

    2016-11-01

    Quantifying the surface to interior transport of anthropogenic carbon (CA) is critical for projecting future carbon uptake and for improved understanding of the role of the oceans in the global carbon cycle. Here we develop and apply a diagnostic tool that provides a volumetric stream function in (CA,σ0) coordinates to calculate the total diapycnal CA transport in the ocean, where σ0 is the surface referenced potential density anomaly. We combine this with air-sea fluxes of CA to infer the internal ocean mixing of CA to obtain a closed globally integrated budget analyses of the ocean's CA transport. This diagnostic separates the contribution from the mean flow, seasonal cycles, trend, surface fluxes, and mixing in the distribution and the accumulation of CA in the ocean. We find that the redistribution of CA from the surface to the interior of the ocean is due to an interplay between circulation and mixing. The circulation component is dominated by the mean flow; however, effects due to seasonal cycles are significant for the CA redistribution. The two most important pathways for CA subduction are through the transformation of thermocline water (TW) into subantarctic mode water and by transformation of Circumpolar Deep Water (CDW) into lighter Antarctic Intermediate Water. The results suggest that an accurate representation of intermediate and mode water formation, deep water formation, and spatial and temporal distribution of ocean mixing in ocean models is essential to simulate and project the oceanic uptake of CA.

  19. Surface characterization and orientation interaction between diamond- like carbon layer structure and dimeric liquid crystals

    NASA Astrophysics Data System (ADS)

    Naradikian, H.; Petrov, M.; Katranchev, B.; Milenov, T.; Tinchev, S.

    2017-01-01

    Diamond-like carbon (DLC) and amorphous carbon films are very promising type of semiconductor materials. Depending on the hybridization sp2/sp3 ratio, the material’s band gap varies between 0.8 and 3 eV. Moreover carbon films possess different interesting for practice properties: comparable to the Silicon, Diamond like structure has 22-time better thermal conductivity etc. Here we present one type of implementation of such type nanostructure. That is one attempt for orientation of dimeric LC by using of pre-deposited DLC layer with different ratio of sp2/sp3 hybridized carbon content. It could be expected a pronounced π1-π2interaction between s and p orbital levels on the surface and the dimeric ring of LC. We present comparison of surface anchoring strengths of both orientation inter-surfaces DLC/dimeric LC and single wall carbon nanotubes (SWCNT)/dimeric LC. The mechanism of interaction of dimeric LC and activated surfaces with DLC or SWCNT will be discussed. In both cases we have π-π interaction, which in combination with hydrogen bonding, typical for the dimeric LCs, influence the LC alignment. The Raman spectroscopy data evidenced the presence of charge transfer between contacting hexagonal rings of DLC and the C = O groups of the LC molecules.

  20. Activated carbon and tungsten oxide supported on activated carbon catalysts for toluene catalytic combustion.

    PubMed

    Alvarez-Merino, M A; Ribeiro, M F; Silva, J M; Carrasco-Marín, F; Maldonado-Hódar, F J

    2004-09-01

    We have used activated carbon (AC) prepared from almond shells as a support for tungsten oxide to develop a series of WOx/AC catalysts for the catalytic combustion of toluene. We conducted the reaction between 300 and 350 degrees C, using a flow of 500 ppm of toluene in air and space velocity (GHSV) in the range 4000-7000 h(-1). Results show that AC used as a support is an appropriate material for removing toluene from dilute streams. By decreasing the GHSV and increasing the reaction temperature AC becomes a specific catalyst for the total toluene oxidation (SCO2 = 100%), but in less favorable conditions CO appears as reaction product and toluene-derivative compounds are retained inside the pores. WOx/AC catalysts are more selective to CO2 than AC due to the strong acidity of this oxide; this behavior improves with increased metal loading and reaction temperature and contact time. The catalytic performance depends on the nonstoichiometric tungsten oxide obtained during the pretreatment. In comparison with other supports the WOx/AC catalysts present, at low reaction temperatures, higher activity and selectivity than WO, supported on SiO2, TiO2, Al2O3, or Y zeolite. This is due to the hydrophobic character of the AC surface which prevents the adsorption of water produced from toluene combustion thus avoiding the deactivation of the active centers. However, the use of WOx/AC system is always restricted by its gasification temperature (around 400 degrees C), which limits the ability to increase the conversion values by increasing reaction temperatures.

  1. An operando surface enhanced Raman spectroscopy (SERS) study of carbon deposition on SOFC anodes.

    PubMed

    Li, Xiaxi; Liu, Mingfei; Lee, Jung-pil; Ding, Dong; Bottomley, Lawrence A; Park, Soojin; Liu, Meilin

    2015-09-07

    Thermally robust and chemically inert Ag@SiO2 nanoprobes are employed to provide the surface enhanced Raman scattering (SERS) effect for an in situ/operando study of the early stage of carbon deposition on nickel-based solid oxide fuel cell (SOFC) anodes. The enhanced sensitivity to carbon enables the detection of different stages of coking, offering insights into intrinsic coking tolerance of material surfaces. Application of a thin coating of gadolinium doped ceria (GDC) enhances the resistance to coking of nickel surfaces. The electrochemically active Ni-YSZ interface appears to be more active for hydrocarbon reforming, resulting in the accumulation of different hydrocarbon molecules, which can be readily removed upon the application of an anodic current. Operando SERS is a powerful tool for the mechanistic study of coking in SOFC systems. It is also applicable to the study of other catalytic and electrochemical processes in a wide range of conditions.

  2. Surface-Activated Coupling Reactions Confined on a Surface.

    PubMed

    Dong, Lei; Liu, Pei Nian; Lin, Nian

    2015-10-20

    Chemical reactions may take place in a pure phase of gas or liquid or at the interface of two phases (gas-solid or liquid-solid). Recently, the emerging field of "surface-confined coupling reactions" has attracted intensive attention. In this process, reactants, intermediates, and products of a coupling reaction are adsorbed on a solid-vacuum or a solid-liquid interface. The solid surface restricts all reaction steps on the interface, in other words, the reaction takes place within a lower-dimensional, for example, two-dimensional, space. Surface atoms that are fixed in the surface and adatoms that move on the surface often activate the surface-confined coupling reactions. The synergy of surface morphology and activity allow some reactions that are inefficient or prohibited in the gas or liquid phase to proceed efficiently when the reactions are confined on a surface. Over the past decade, dozens of well-known "textbook" coupling reactions have been shown to proceed as surface-confined coupling reactions. In most cases, the surface-confined coupling reactions were discovered by trial and error, and the reaction pathways are largely unknown. It is thus highly desirable to unravel the mechanisms, mechanisms of surface activation in particular, of the surface-confined coupling reactions. Because the reactions take place on surfaces, advanced surface science techniques can be applied to study the surface-confined coupling reactions. Among them, scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS) are the two most extensively used experimental tools. The former resolves submolecular structures of individual reactants, intermediates, and products in real space, while the latter monitors the chemical states during the reactions in real time. Combination of the two methods provides unprecedented spatial and temporal information on the reaction pathways. The experimental findings are complemented by theoretical modeling. In particular, density

  3. On the formation and bonding of a surface carbonate on Ni(100)

    NASA Astrophysics Data System (ADS)

    Behm, R. J.; Brundle, C. R.

    1991-09-01

    The formation, stability, adsorption geometry and electronic structure of a surface carbonate on Ni(100) have been investigated by photoemission (XPS, UPS) and temperature-programmed reaction (TPR). The core level binding energies of 531.2 eV for 0(1s) and 289.0 eV for C(1s) are comparable to those of bulk carbonates. The He(II) spectrum of the carbonate valence levels is not well defined because of the coexisting adsorbed and oxidic oxygen. The angular dependence of the carbonate core level intensities is characteristic of the carbonate being present as an overlayer species rather than a thicker surface phase. The XPS data and isotope labelled TPR experiments indicate the oxygen atoms of the carbonate to be electronically and chemically equivalent, and on this basis we favor a structure in which the carbonate is attached to the metal via all three oxygen atoms. This is supported by comparision with the core level binding energies of HCOO ab and chemisorbed CO 2,ad, which are similarly attached to the surface. From the core level angular behavior, the close similarity of core level binding energies and available vibrational spectroscopic data, a (nearly) planar geometry of the CO 3,ad on Ni(100) is concluded, which is comparable to the planar bulk carbonate anion and the planar carbonate species on Ag(110). The activation barrier for decomposition is estimated from the observed maximum in TPR at 420 K to be 25 ± 2 kcal/mol. CO 2 does not accumulate on the clean or O ad-precovered Ni(100) surface at 130 K. The stabilized, chemisorbed CO 2,ad species often observed on other metal surfaces therefore does not play a critical role for carbonate formation on Ni(100). Also a mechanism involving the disproportionation of a CO 2… CO 2,ad- dimer anion can be ruled out from TPR data. The evidence of the experiments discussed in this paper suggests that the carbonate is predominantly formed by reaction of CO 2,ad with a less stable, defect (disordered) O ad species rather

  4. Characteristic and mercury adsorption of activated carbon produced by CO2 of chicken waste.

    PubMed

    Huang, Yaji; Jin, Baosheng; Zhong, Zhaoping; Zhong, Wenqi; Xiao, Rui

    2008-01-01

    Preparation of activated carbon from chicken waste is a promising way to produce a useful adsorbent for Hg removal. A three-stage activation process (drying at 200 degrees C, pyrolysis in N2 atmosphere, followed by CO2 activation) was used for the production of activated samples. The effects of carbonization temperature (400-600 degrees C), activation temperature (700-900 degrees C), and activation time (1-2.5 h) on the physicochemical properties (weight-loss and BET surface) of the prepared carbon were investigated. Adsorptive removal of mercury from real flue gas onto activated carbon has been studied. The activated carbon from chicken waste has the same mercury capacity as commercial activated carbon (Darco LH) (Hg(v): 38.7% vs. 53.5%, Hg(0): 50.5% vs. 68.8%), although its surface area is around 10 times smaller, 89.5 m2/g vs. 862 m2/g. The low cost activated carbon can be produced from chicken waste, and the procedure is suitable.

  5. Adsorption characteristics of SO2 on activated carbon prepared from coconut shell with potassium hydroxide activation.

    PubMed

    Lee, Young-Whan; Park, Jin-Won; Choung, Jae-Hoon; Choi, Dae-Ki

    2002-03-01

    The adsorption characteristics of SO2 were studied with KOH-impregnated granular activated carbon (K-IAC). To confirm selective SO2 adsorptivity of K-IAC using a fixed bed adsorption column, experiments were conducted on the effects of KOH and of linear velocity, temperature, and concentration. In addition, changes in features before and after adsorption were observed by utilizing FTIR, XRD, ToF-SIMS, and AES/SAM, examining the surface chemistry. K-IAC adsorbed 13.2 times more SO2 than did general activated carbon (GAC). The amount of SO2 adsorbed increased as linear velocity and concentration increased and as temperature decreased. At lower temperature, the dominant reaction between KOH and SO2 produces K2-SO3 and H2O. Any H2O remaining on the surface is converted into H2SO4 as SO2 and O2 are introduced. Then, the KOH and SO2 reaction produces K2SO4 and H2O. The surface characterization results proved that adsorption occurred through chemical reaction between KOH and SO2. The SO2 adsorbed K-IAC exists in the form of stable oxide crystal, K2SO3 and K2SO4, due to potassium. The basic feature given to the surface of activated carbon by KOH impregnation was confirmed to be acting as the main factor in enhancing SO2 adsorptivity.

  6. Improved Composites Using Crosslinked, Surface-Modified Carbon Nanotube Materials

    NASA Technical Reports Server (NTRS)

    Baker, James Stewart

    2014-01-01

    Individual carbon nanotubes (CNTs) exhibit exceptional tensile strength and stiffness; however, these properties have not translated well to the macroscopic scale. Premature failure of bulk CNT materials under tensile loading occurs due to the relatively weak frictional forces between adjacent CNTs, leading to poor load transfer through the material. When used in polymer matrix composites (PMCs), the weak nanotube-matrix interaction leads to the CNTs providing less than optimal reinforcement.Our group is examining the use of covalent crosslinking and surface modification as a means to improve the tensile properties of PMCs containing carbon nanotubes. Sheet material comprised of unaligned multi-walled carbon nanotubes (MWCNT) was used as a drop-in replacement for carbon fiber in the composites. A variety of post-processing methods have been examined for covalently crosslinking the CNTs to overcome the weak inter-nanotube shear interactions, resulting in improved tensile strength and modulus for the bulk sheet material. Residual functional groups from the crosslinking chemistry may have the added benefit of improving the nanotube-matrix interaction. Composites prepared using these crosslinked, surface-modified nanotube sheet materials exhibit superior tensile properties to composites using the as received CNT sheet material.

  7. Friction Properties of Surface-Fluorinated Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Wal, R. L. Vander; Miyoshi, K.; Street, K. W.; Tomasek, A. J.; Peng, H.; Liu, Y.; Margrave, J. L.; Khabashesku, V. N.

    2005-01-01

    Surface modification of the tubular or sphere-shaped carbon nanoparticles through chemical treatment, e.g., fluorination, is expected to significantly affect their friction properties. In this study, a direct fluorination of the graphene-built tubular (single-walled carbon nanotubes) structures has been carried out to obtain a series of fluorinated nanotubes (fluoronanotubes) with variable C(n)F (n =2-20) stoichiometries. The friction coefficients for fluoronanotubes, as well as pristine and chemically cut nanotubes, were found to reach values as low as 0.002-0.07, according to evaluation tests run in contact with sapphire in air of about 40% relative humidity on a ball-on-disk tribometer which provided an unidirectional sliding friction motion. These preliminary results demonstrate ultra-low friction properties and show a promise in applications of surface modified nanocarbons as a solid lubricant.

  8. Ocean Surface Carbon Dioxide Fugacity Observed from Space

    NASA Technical Reports Server (NTRS)

    Liu, W. Timothy; Xie, Xiaosu

    2014-01-01

    We have developed and validated a statistical model to estimate the fugacity (or partial pressure) of carbon dioxide (CO2) at sea surface (pCO2sea) from space-based observations of sea surface temperature (SST), chlorophyll, and salinity. More than a quarter million in situ measurements coincident with satellite data were compiled to train and validate the model. We have produced and made accessible 9 years (2002-2010) of the pCO2sea at 0.5 degree resolutions daily over the global ocean. The results help to identify uncertainties in current JPL Carbon Monitoring System (CMS) model-based and bottom-up estimates over the ocean. The utility of the data to reveal multi-year and regional variability of the fugacity in relation to prevalent oceanic parameters is demonstrated.

  9. Adventitious Carbon on Primary Sample Containment Metal Surfaces

    NASA Technical Reports Server (NTRS)

    Calaway, M. J.; Fries, M. D.

    2015-01-01

    Future missions that return astromaterials with trace carbonaceous signatures will require strict protocols for reducing and controlling terrestrial carbon contamination. Adventitious carbon (AC) on primary sample containers and related hardware is an important source of that contamination. AC is a thin film layer or heterogeneously dispersed carbonaceous material that naturally accrues from the environment on the surface of atmospheric exposed metal parts. To test basic cleaning techniques for AC control, metal surfaces commonly used for flight hardware and curating astromaterials at JSC were cleaned using a basic cleaning protocol and characterized for AC residue. Two electropolished stainless steel 316L (SS- 316L) and two Al 6061 (Al-6061) test coupons (2.5 cm diameter by 0.3 cm thick) were subjected to precision cleaning in the JSC Genesis ISO class 4 cleanroom Precision Cleaning Laboratory. Afterwards, the samples were analyzed by X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy.

  10. Physical and chemical properties and adsorption type of activated carbon prepared from plum kernels by NaOH activation.

    PubMed

    Tseng, Ru-Ling

    2007-08-25

    Activated carbon was prepared from plum kernels by NaOH activation at six different NaOH/char ratios. The physical properties including the BET surface area, the total pore volume, the micropore ratio, the pore diameter, the burn-off, and the scanning electron microscope (SEM) observation as well as the chemical properties, namely elemental analysis and temperature programmed desorption (TPD), were measured. The results revealed a two-stage activation process: stage 1 activated carbons were obtained at NaOH/char ratios of 0-1, surface pyrolysis being the main reaction; stage 2 activated carbons were obtained at NaOH/char ratios of 2-4, etching and swelling being the main reactions. The physical properties of stage 2 activated carbons were similar, and specific area was from 1478 to 1887m(2)g(-1). The results of reaction mechanism of NaOH activation revealed that it was apparently because of the loss ratio of elements C, H, and O in the activated carbon, and the variations in the surface functional groups and the physical properties. The adsorption of the above activated carbons on phenol and three kinds of dyes (MB, BB1, and AB74) were used for an isotherm equilibrium adsorption study. The data fitted the Langmuir isotherm equation. Various kinds of adsorbents showed different adsorption types; separation factor (R(L)) was used to determine the level of favorability of the adsorption type. In this work, activated carbons prepared by NaOH activation were evaluated in terms of their physical properties, chemical properties, and adsorption type; and activated carbon PKN2 was found to have most application potential.

  11. Natural variability in the surface ocean carbonate ion concentration

    NASA Astrophysics Data System (ADS)

    Lovenduski, N. S.; Long, M. C.; Lindsay, K.

    2015-11-01

    We investigate variability in the surface ocean carbonate ion concentration ([CO32-]) on the basis of a~long control simulation with an Earth System Model. The simulation is run with a prescribed, pre-industrial atmospheric CO2 concentration for 1000 years, permitting investigation of natural [CO32-] variability on interannual to multi-decadal timescales. We find high interannual variability in surface [CO32-] in the tropical Pacific and at the boundaries between the subtropical and subpolar gyres in the Northern Hemisphere, and relatively low interannual variability in the centers of the subtropical gyres and in the Southern Ocean. Statistical analysis of modeled [CO32-] variance and autocorrelation suggests that significant anthropogenic trends in the saturation state of aragonite (Ωaragonite) are already or nearly detectable at the sustained, open-ocean time series sites, whereas several decades of observations are required to detect anthropogenic trends in Ωaragonite in the tropical Pacific, North Pacific, and North Atlantic. The detection timescale for anthropogenic trends in pH is shorter than that for Ωaragonite, due to smaller noise-to-signal ratios and lower autocorrelation in pH. In the tropical Pacific, the leading mode of surface [CO32-] variability is primarily driven by variations in the vertical advection of dissolved inorganic carbon (DIC) in association with El Niño-Southern Oscillation. In the North Pacific, surface [CO32-] variability is caused by circulation-driven variations in surface DIC and strongly correlated with the Pacific Decadal Oscillation, with peak spectral power at 20-30-year periods. North Atlantic [CO32-] variability is also driven by variations in surface DIC, and exhibits weak correlations with both the North Atlantic Oscillation and the Atlantic Multidecadal Oscillation. As the scientific community seeks to detect the anthropogenic influence on ocean carbonate chemistry, these results will aid the interpretation of trends

  12. Natural variability in the surface ocean carbonate ion concentration

    NASA Astrophysics Data System (ADS)

    Lovenduski, N. S.; Long, M. C.; Lindsay, K.

    2015-08-01

    We investigate variability in the surface ocean carbonate ion concentration ([CO32-]) on the basis of a long control simulation with a fully-coupled Earth System Model. The simulation is run with a prescribed, pre-industrial atmospheric CO2 concentration for 1000 years, permitting investigation of natural [CO32-] variability on interannual to multi-decadal timescales. We find high interannual variability in surface [CO32-] in the tropical Pacific and at the boundaries between the subtropical and subpolar gyres in the Northern Hemisphere, and relatively low interannual variability in the centers of the subtropical gyres and in the Southern Ocean. Statistical analysis of modeled [CO32-] variance and autocorrelation suggests that significant anthropogenic trends in the saturation state of aragonite (Ωaragonite) are already or nearly detectable at the sustained, open-ocean timeseries sites, whereas several decades of observations are required to detect anthropogenic trends in Ωaragonite in the tropical Pacific, North Pacific, and North Atlantic. The detection timescale for anthropogenic trends in pH is shorter than that for Ωaragonite, due to smaller noise-to-signal ratios and lower autocorrelation in pH. In the tropical Pacific, the leading mode of surface [CO32-] variability is primarily driven by variations in the vertical advection of dissolved inorganic carbon (DIC) in association with El Niño-Southern Oscillation. In the North Pacific, surface [CO32-] variability is caused by circulation-driven variations in surface DIC and strongly correlated with the Pacific Decadal Oscillation, with peak spectral power at 20-30 year periods. North Atlantic [CO32-] variability is also driven by variations in surface DIC, and exhibits weak correlations with both the North Atlantic Oscillation and the Atlantic Multidecadal Oscillation. As the scientific community seeks to detect the anthropogenic influence on ocean carbonate chemistry, these results will aid the

  13. Surface Analysis of sp2 Carbon in Ag and Al Covetic Alloys*

    NASA Astrophysics Data System (ADS)

    Jaim, H. M. Iftekhar; Cole, Daniel P.; Salamanca-Riba, Lourdes G.

    Ag, Al-6061 and Al-7075 were doped with carbon by an electrocharging assisted process where high electric current is applied to the molten metal containing particles of activated carbon. This process gives rise to epitaxial growth of graphene nanoribbons (GNR) and carbon nanostructures within the metal matrix. Alloys produced with such technique are named Covetics. Al-6061 and Al-7075 covetics have shown superior mechanical, electrical and anti-corrosion properties. The nanostructured carbon incorporation has been confirmed by XPS, Raman, and TEM studies. Here, we present detailed surface characterization of the carbon nanostructures in these new alloys. Raman and EELS mapping of carbon nanostructure were carried out to identify the nature of bonding, strain and defect characteristics. Mostly, crystalline GNR or graphene sheets were found to create networks with sp2 character, under compressive strain with high concentration of defects. AFM and KPFM showed contrast in phases and potentials for ribbon like features. Incorporation of sp2 carbon in metals is an initial step for the integration of carbon nanostructures for future applications requiring high strength and conductivity.

  14. Modeling high adsorption capacity and kinetics of organic macromolecules on super-powdered activated carbon.

    PubMed

    Matsui, Yoshihiko; Ando, Naoya; Yoshida, Tomoaki; Kurotobi, Ryuji; Matsushita, Taku; Ohno, Koichi

    2011-02-01

    The capacity to adsorb natural organic matter (NOM) and polystyrene sulfonates (PSSs) on small particle-size activated carbon (super-powdered activated carbon, SPAC) is higher than that on larger particle-size activated carbon (powdered-activated carbon, PAC). Increased adsorption capacity is likely attributable to the larger external surface area because the NOM and PSS molecules do not completely penetrate the adsorbent particle; they preferentially adsorb near the outer surface of the particle. In this study, we propose a new isotherm equation, the Shell Adsorption Model (SAM), to explain the higher adsorption capacity on smaller adsorbent particles and to describe quantitatively adsorption isotherms of activated carbons of different particle sizes: PAC and SPAC. The SAM was verified with the experimental data of PSS adsorption kinetics as well as equilibrium. SAM successfully characterized PSS adsorption isotherm data for SPACs and PAC simultaneously with the same model parameters. When SAM was incorporated into an adsorption kinetic model, kinetic decay curves for PSSs adsorbing onto activated carbons of different particle sizes could be simultaneously described with a single kinetics parameter value. On the other hand, when SAM was not incorporated into such an adsorption kinetic model and instead isotherms were described by the Freundlich model, the kinetic decay curves were not well described. The success of the SAM further supports the adsorption mechanism of PSSs preferentially adsorbing near the outer surface of activated carbon particles.

  15. Physicochemical characteristics and sorption capacities of heavy metal ions of activated carbons derived by activation with different alkyl phosphate triesters

    NASA Astrophysics Data System (ADS)

    Wang, Jing; Liu, Hai; Yang, Shaokun; Zhang, Jian; Zhang, Chenglu; Wu, Haiming

    2014-10-01

    Five alkyl phosphate triesters (APTEs), including trimethyl phosphate (TMP), triethyl phosphate (TEP), triisopropyl phosphate (TPP), tributyl phosphate (TBP) and trioctyl phosphate (TOP), were used as activating agents for preparing activated carbons (AC-APTEs) with high surface acidity and metal ion sorption capacity. N2 adsorption/desorption isotherms, surface morphologies, elemental compositions, results of Boehm's titration and sorption capacities of heavy metal ions of the carbons were investigated. AC-APTEs contained much more acidic groups and exhibited much less surface area (<500 m2/g) in comparison with activated carbon (AC-PPA, 1145 m2/g) obtained from phosphoric acid activation. For the AC-APTEs, AC-TOP had the highest surface area (488 m2/g), AC-TMP showed the highest yield (41.1%), and AC-TBP possessed the highest acidic groups (2.695 mmol/g), oxygen content (47.0%) and metal ion sorption capacities (40.1 mg/g for Ni(II) and 53.5 mg/g for Cd(II)). For the carbons, AC-APTEs showed much larger Ni(II) and Cd(II) sorption capacities than AC-PPA, except AC-TPP. The differences of the carbons in the physicochemical and sorption properties suggested surface chemistry of the carbons was the main factor influencing their sorption capacities whereas the pore structure played a secondary role.

  16. Adsorption ability comparison of plasma proteins on amorphous carbon surface

    NASA Astrophysics Data System (ADS)

    Takeda, Aoi; Akasaka, Hiroki; Ohshio, Shigeo; Toda, Ikumi; Nakano, Masayuki; Saitoh, Hidetoshi

    2012-11-01

    To understand why amorphous carbon (a-C:H) film shows antithrombogenicity, an adsorption ability of plasma proteins on a-C:H surface was investigated. Protein adsorption is the initial process of clot formation. The protein adsorption ability on a-C:H film surface was compared by the detection using the surface plasmon resonance (SPR) phenomenon to estimate the protein adsorption. The protein adsorption abilities of a fibrinogen (Fib) and a human γ-globulin (HGG) were estimated by the SPR method using a multilayer structure of a-C:H/Au/Cr/glass. Although the adsorption of HGG for a-C:H was saturated at 32 μM in HGG concentration, the adsorption of Fib was not saturated under the detection limit of this method. These results indicated that the adsorption ability to the a-C:H film surface of Fib was higher than HGG.

  17. Surface treatment of Glassy Polymeric Carbon artifacts for medical applications

    SciTech Connect

    Rodrigues, M. G.; Zimmerman, R. L.; Rezende, M. C.

    1999-06-10

    Glassy Polymeric Carbon (GPC) has been used for mechanical cardiac valves. GCP valves are chemically biocompatible and durable, but less thromboresistant than biological valves. Enhanced thromboresistance of mechanical cardiac components with porous surface has been demonstrated. The endothelialized tissue blood-contacting surface adheres to the porous prosthetic component and decreases the formation of thrombus. Our experience has shown that the porosity of GPC can be increased and controlled by MeV ion bombardment. We report here that the surface roughness of heat-treated GPC bombarded with C, O, Si and Au is also enhanced. The surface roughness of the ion-bombarded samples is on a smaller scale than those roughened by sand blasting (measurements made with Perthomete S and P). The roughness decreases slightly after heat treatment, in linear proportion to the shrinkage of the test piece. Possible beneficial effects of the imbedded ions on tissue adherence and thromboresistance must be determined by in vivo animal experiments.

  18. Photochemically modified diamond-like carbon surfaces for neural interfaces.

    PubMed

    Hopper, A P; Dugan, J M; Gill, A A; Regan, E M; Haycock, J W; Kelly, S; May, P W; Claeyssens, F

    2016-01-01

    Diamond-like carbon (DLC) was modified using a UV functionalization method to introduce surface-bound amine and aldehyde groups. The functionalization process rendered the DLC more hydrophilic and significantly increased the viability of neurons seeded to the surface. The amine functionalized DLC promoted adhesion of neurons and fostered neurite outgrowth to a degree indistinguishable from positive control substrates (glass coated with poly-L-lysine). The aldehyde-functionalized surfaces performed comparably to the amine functionalized surfaces and both additionally supported the adhesion and growth of primary rat Schwann cells. DLC has many properties that are desirable in biomaterials. With the UV functionalization method demonstrated here it may be possible to harness these properties for the development of implantable devices to interface with the nervous system.

  19. Electric arc surfacing on low carbon steel: Structure and properties

    NASA Astrophysics Data System (ADS)

    Ivanov, Yurii; Gromov, Victor; Kormyshev, Vasilii; Konovalov, Sergey; Kapralov, Evgenii; Semin, Alexander

    2016-11-01

    By the methods of modern materials science, the structure-phase state and microhardness distribution along the cross-section of single and double coatings surfaced on martensite low carbon steel by alloy powder-cored wire were studied. It was established that the increased mechanical properties of surfaced layer are determined by the sub-micro and nanodispersed martensite structure formation, containing iron borides forming the eutectic of lamellar form. The plates of Fe2B are formed mainly in the eutectic of a single-surfaced layer, while FeB is formed in a double-surfaced layer. The existence of bend extinction contours indicating the internal stress fields formation at the boundaries of Fe borides-α-Fe phases were revealed.

  20. Cooperative redox activation for carbon dioxide conversion

    PubMed Central

    Lian, Zhong; Nielsen, Dennis U.; Lindhardt, Anders T.; Daasbjerg, Kim; Skrydstrup, Troels

    2016-01-01

    A longstanding challenge in production chemistry is the development of catalytic methods for the transformation of carbon dioxide into useful chemicals. Silane and borane promoted reductions can be fined-tuned to provide a number of C1-building blocks under mild conditions, but these approaches are limited because of the production of stoichiometric waste compounds. Here we report on the conversion of CO2 with diaryldisilanes, which through cooperative redox activation generate carbon monoxide and a diaryldisiloxane that actively participate in a palladium-catalysed carbonylative Hiyama-Denmark coupling for the synthesis of an array of pharmaceutically relevant diarylketones. Thus the disilane reagent not only serves as the oxygen abstracting agent from CO2, but the silicon-containing ‘waste', produced through oxygen insertion into the Si–Si bond, participates as a reagent for the transmetalation step in the carbonylative coupling. Hence this concept of cooperative redox activation opens up for new avenues in the conversion of CO2. PMID:27981967

  1. Hierarchical porous carbon with ultrahigh surface area from corn leaf for high-performance supercapacitors application

    NASA Astrophysics Data System (ADS)

    Yang, Xiaoqing; Li, Chengfei; Chen, Yue

    2017-02-01

    A new class of hierarchical porous carbon (HPC) with ultrahigh surface area is successfully fabricated by carefully selecting biomass carbon precursors and activation reagent, through which corn leaf (CL) with natural well-defined macropore channels is used as the carbon precursor, and H3PO4 is used as the active agent by virtue of its pore-widening effect. The as-prepared CL-based HPC (CLHPC) with a H3PO4/semi-carbonized CL mass ratio of 2 (CLHPC-2) demonstrates the highest specific surface area of 2507 m2 g-1 donated by 28.3% of micropore and 71.6% of mesopore, while maintaining the channel-like macroporous structure derived from the well-defined natural structure in CL. The combination of the hierarchical porous structure and ultrahigh surface area enables rapid electrolyte diffusion and sufficient active sites for charge accumulation. As a result, CLHPC-2 exhibits excellent electrochemical performance, such as high specific capacitance of 230 F g-1 at the current density of 0.1 A g-1, excellent high-rate capability (retention of 91% from 0.1 to 5 A g-1), and good cycling stability (99% capacitance retention after 10 000 cycles).

  2. 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.

  3. 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.

  4. Surface properties and blood compatibility of commercially available diamond-like carbon coatings for cardiovascular devices.

    PubMed

    Fedel, Mariangela; Motta, Antonella; Maniglio, Devid; Migliaresi, Claudio

    2009-07-01

    The aim of this study was to determine the relationships between the surface properties and blood compatibility of in-use diamond-like carbon (DLC) coatings for cardiovascular components. Commercially available DLC films were characterized with respect to surface topography and wettability, protein adsorption from human plasma, and platelets adhesion/activation. Fibrinogen (Fng) and human serum albumin (HSA) adsorbed onto the sample surfaces were in particular quantified as two of the main proteins involved in blood compatibility. A low tendency of platelets to spread and form aggregates onto the DLC-coated surfaces has been described and related to a low Fng-to-HSA adsorption ratio. This study provides evidence that the rapid and tenacious binding of albumin molecules to DLC materials tends to passivate the surfaces and to inhibit Fng adsorption, thus imparting thromboresistance to the carbon coatings by rendering the surfaces less adhesive and activating for platelets. Albumin preferential adsorption was ascribed to high chemical heterogeneity of the DLC sample surfaces. The DLC films tested present a favorable behavior as regards blood compatibility with respect to platelet thrombus formation by reason of their surface properties.

  5. 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.

  6. Water treatment using activated carbon supporting silver and magnetite.

    PubMed

    Valušová, Eva; Vandžurová, Anna; Pristaš, Peter; Antalík, Marián; Javorský, Peter

    2012-01-01

    Recent efforts in water purification have led to the development of novel materials whose unique properties can offer effective biocidal capabilities with greater ease of use and at lower cost. In this study, we introduce a novel procedure for the preparation of activated carbon (charcoal) composite in which magnetite and silver are incorporated (MCAG); we also describe the use of this material for the disinfection of surface water. The formation process of magnetic MCAG composite was studied using ultraviolet-visible spectroscopy. The results demonstrated the high sorption efficiency of AgNO₃ to magnetic activated carbon. The antimicrobial capabilities of the prepared MCAG were examined and the results clearly demonstrate their inhibitory effect on total river water bacteria and on Pseudomonas koreensis and Bacillus mycoides cultures isolated from river water. The bacterial counts in river water samples were reduced by five orders of magnitude following 30 min of treatment using 1 g l⁻¹ of MCAG at room temperature. The removal of all bacteria from the surface water samples implies that the MCAG material would be a suitable disinfectant for such waters. In combination with its magnetic character, MCAG would be an excellent candidate for the simple ambulatory disinfection of surface water.

  7. Metal chlorides loaded on activated carbon to capture elemental mercury.

    PubMed

    Shen, Zhemin; Ma, Jing; Mei, Zhijian; Zhang, Jianda

    2010-01-01

    Activated carbon (AC) was considered to be an effective sorbent to control mercury in combustion systems. However, its capture capacity was low and it required a high carbon-to-mercury mass ratio. AC loaded with catalyst showed a high elemental mercury (Hg0) capture capacity due to large surface area of AC and high oxidization ability of catalyst. In this study, several metal chlorides and metal oxides were used to promote the sorption capacity of AC. As a result, metal chlorides were better than metal oxides loaded on AC to remove gaseous mercury. X-ray diffractometer (XRD), thermogravimetric analyzer (TGA) and specific surface area by Brunauer-Emmett-Teller method (BET) analysis showed the main mechanisms: first, AC had an enormous surface area for loading enough MClx; second, Cl and MxOy were generated during pyrogenation of MClx; finally, there were lots of active elements such as Cl and MxOy which could react with elemental mercury and convert it to mercury oxide and mercury chloride. The HgO and HgCl2 might be released from AC's porous structure by thermo regeneration. A catalytic chemisorption mechanism predominates the sorption process of elemental mercury. As Co and Mn were valence variable metal elements, their catalytic effect on Hg0 oxidization may accelerate both oxidation and halogenation of Hg0. The sorbents loaded with metal chlorides possessed a synergistic function of catalytic effect of valence variable metal and chlorine oxidation.

  8. Characterization of activated carbon prepared from chicken waste and coal

    SciTech Connect

    Yan Zhang; Hong Cui; Riko Ozao; Yan Cao; Bobby I.-T. Chen; Chia-Wei Wang; Wei-Ping Pan

    2007-12-15

    Activated carbons (ACs) were prepared from chicken waste (CW) and coal (E-coal) blended at the ratios of 100:0, 80:20, 50:50, 20:80, and 0:100. The process included carbonization in flowing gaseous nitrogen (300 mL min{sup -1}) at ca. 430{sup o}C for 60 min and successive steam activation (0.1 mL min{sup -1} water injection with a flow of N{sub 2} at 100 mL min{sup -1}) at 650{sup o}C for 30 min. Chicken waste is low in sulfur content but is high in volatile matter (about 55 wt %), and ACs with higher specific surface area were more successfully obtained by mixing with coal. The specific surface area of the CW/Coal blend AC can be estimated by SSA{sub BET} = -65.8x{sup 2} + 158x + 168, where SSA{sub BET} is the specific surface area in m{sup 2} g{sup -1} as determined by the BET method using CO{sub 2} as the adsorbent, where x is the coal fraction by weight in the CW/coal blend ranging from 0.0 to 1.0 (e.g., x = 0.0 signifies the blend contains no coal and x = 1.0 signifies the blend consists of 100% coal). 26 refs., 7 figs., 3 tabs.

  9. Adsorption onto fluidized powdered activated carbon flocs-pACF.

    PubMed

    Serpa, Ana Lídia; Schneider, Ivo André H; Rubio, Jorge

    2005-02-01

    This work presents a new adsorption technique where the adsorbent (powdered activated carbon-PAC) is in the form of suspended flocs formed with water-soluble polymer flocculants. Thus, the adsorption of a typical dye, methylene blue (MB), was studied onto polyacrylamide flocs of PAC (PACF) in a fluidized bed reactor. The technique is based on the fact that the adsorption capacity of PAC does not decrease after flocculation because the adsorbed polymer occupies only a few surface sites, in the form of trains, loops, and tails. Moreover, the adsorption was found to proceed through a rapid mass transfer of MB to the adsorbing PAC flocs, in the same extent as onto PAC. Because of the rapid settling characteristics of the aggregates formed, the two phase separations, loaded PAC and solution, become easier. Thus, the technique offers the advantages of conducting simultaneously both adsorption and solid/liquid separation all in one single stage. Results obtained showed that high MB removal values can be attained in a fluidized bed reactor (>90%) and that PACF presents a much higher adsorption capacity (breakthrough points) than granulated activated carbon (GAC) in the same adsorbing bed. It is believed that this technique highly broadens the potential of the use of powdered activated carbon or other similar ultrafine adsorbents.

  10. ENTRAINED-FLOW ADSORPTION OF MERCURY USING ACTIVATED CARBON

    EPA Science Inventory

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

  11. Activated-Carbon Sorbent With Integral Heat-Transfer Device

    NASA Technical Reports Server (NTRS)

    Jones, Jack A.; Yavrouian, Andre

    1996-01-01

    Prototype adsorption device used, for example, in adsorption heat pump, to store natural gas to power automobile, or to separate components of fluid mixtures. Device includes activated carbon held together by binder and molded into finned heat-transfer device providing rapid heating or cooling to enable rapid adsorption or desorption of fluids. Concepts of design and fabrication of device equally valid for such other highly thermally conductive devices as copper-finned tubes, and for such other high-surface-area sorbents as zeolites or silicates.

  12. Conducting polymer transistors making use of activated carbon gate electrodes.

    PubMed

    Tang, Hao; Kumar, Prajwal; Zhang, Shiming; Yi, Zhihui; Crescenzo, Gregory De; Santato, Clara; Soavi, Francesca; Cicoira, Fabio

    2015-01-14

    The characteristics of the gate electrode have significant effects on the behavior of organic electrochemical transistors (OECTs), which are intensively investigated for applications in the booming field of organic bioelectronics. In this work, high specific surface area activated carbon (AC) was used as gate electrode material in OECTs based on the conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) doped with poly(styrenesulfonate) (PSS). We found that the high specific capacitance of the AC gate electrodes leads to high drain-source current modulation in OECTs, while their intrinsic quasi-reference characteristics make unnecessary the presence of an additional reference electrode to monitor the OECT channel potential.

  13. Plant diversity increases soil microbial activity and soil carbon storage.

    PubMed

    Lange, Markus; Eisenhauer, Nico; Sierra, Carlos A; Bessler, Holger; Engels, Christoph; Griffiths, Robert I; Mellado-Vázquez, Perla G; Malik, Ashish A; Roy, Jacques; Scheu, Stefan; Steinbeiss, Sibylle; Thomson, Bruce C; Trumbore, Susan E; Gleixner, Gerd

    2015-04-07

    Plant diversity strongly influences ecosystem functions and services, such as soil carbon storage. However, the mechanisms underlying the positive plant diversity effects on soil carbon storage are poorly understood. We explored this relationship using long-term data from a grassland biodiversity experiment (The Jena Experiment) and radiocarbon ((14)C) modelling. Here we show that higher plant diversity increases rhizosphere carbon inputs into the microbial community resulting in both increased microbial activity and carbon storage. Increases in soil carbon were related to the enhanced accumulation of recently fixed carbon in high-diversity plots, while plant diversity had less pronounced effects on the decomposition rate of existing carbon. The present study shows that elevated carbon storage at high plant diversity is a direct function of the soil microbial community, indicating that the increase in carbon storage is mainly limited by the integration of new carbon into soil and less by the decomposition of existing soil carbon.

  14. Comparative Study of Surface-Active Properties and Antimicrobial Activities of Disaccharide Monoesters

    PubMed Central

    Zhang, Xi; Song, Fei; Taxipalati, Maierhaba; Wei, Wei; Feng, Fengqin

    2014-01-01

    The objective of this research was to determine the effect of sugar or fatty acid in sugar ester compounds on the surface-active properties and antimicrobial activities of these compounds. Disaccharides of medium-chain fatty acid monoesters were synthesized through transesterifications by immobilized lipase (Lipozyme TLIM) to yield nine monoesters for subsequent study. Their antimicrobial activities were investigated using three pathogenic microorganisms: Staphylococcus aureus, Escherichia coli O157:H7 and Candida albicans. Their surface-active properties including air–water surface tension, critical micelle concentration, and foaming and emulsion power and stability were also studied. The results showed that all of the tested monoesters were more effective against Staphylococcus aureus (Gram-positive bacterium) than against Escherichia coli O157:H7 (Gram-negative bacterium). The results demonstrated that the carbon chain length was the most important factor influencing the surface properties, whereas degree of esterification and hydrophilic groups showed little effect. PMID:25531369

  15. Immobilization of Active Bacteriophages on Polyhydroxyalkanoate Surfaces.

    PubMed

    Wang, Chanchan; Sauvageau, Dominic; Elias, Anastasia

    2016-01-20

    A rapid, efficient technique for the attachment of bacteriophages (phages) onto polyhydroxyalkanoate (PHA) surfaces has been developed and compared to three reported methods for phage immobilization. Polymer surfaces were modified to facilitate phage attachment using (1) plasma treatment alone, (2) plasma treatment followed by activation by 1-ethyl-3-(3-(dimethylamino)propyl)carbodiimide hydrochloride (EDC) and N-hydroxysulfosuccinimide (sulfo-NHS), (3) plasma-initiated acrylic acid grafting, or (4) plasma-initiated acrylic acid grafting with activation by EDC and sulfo-NHS. The impact of each method on the surface chemistry of PHA was investigated using contact angle analysis and X-ray photoelectron spectroscopy. Each of the four treatments was shown to result in both increased hydrophilicity and in the modification of the surface functional groups. Modified surfaces were immersed in suspensions of phage T4 for immobilization. The highest level of phage binding was observed for the surfaces modified by plasma treatment alone. The change in chemical bond states observed for surfaces that underwent plasma treatment is suspected to be the cause of the increased binding of active phages. Plasma-treated surfaces were further analyzed through phage-staining and fluorescence microscopy to assess the surface density of immobilized phages and their capacity to capture hosts. The infective capability of attached phages was confirmed by exposing the phage-immobilized surfaces to the host bacteria Escherichia coli in both plaque and infection dynamic assays. Plasma-treated surfaces with immobilized phages displayed higher infectivity than surfaces treated with other methods; in fact, the equivalent initial multiplicity of infection was 2 orders of magnitude greater than with other methods. Control samples - prepared by immersing polymer surfaces in phage suspensions (without prior plasma treatment) - did not show any bacterial growth inhibition, suggesting they did not bind

  16. Studies of the Surface Treatment and Sizing of Carbon Fiber Surfaces on the Mechanical Properties of Composites Containing Carbon Fibers

    NASA Technical Reports Server (NTRS)

    Sherwood, Peter M. A.; Lease, Kevin B.; Locke, James E.; Tomblin, John S.; Wang, Youqi

    1996-01-01

    Carbon fiber reinforced composites are materials where carbon fibers are used to reinforce a matrix to produce a light and strong material with important applications in the aerospace industry. There are many aspects of the preparation of these materials that would benefit from a study which combines the research of groups involved in the production, testing and analysis of these materials, and studies of the basic surface chemistry involved. This final reports presents the results of a project that has developed a collaboration between groups in all three of the major research universities in the State of Kansas, and promises to lead to a collaborative program that covers the major aspects of composite development and application. Sherwood has provided initial fiber surface treatment and sizing together with fiber and composite surface analysis; Lease, Tomblin and Wang have worked together toward the goal of preparing pre-preg and fabrication of laminated panels; Locke has developed computational models to evaluate the effect of surface treatment (and chemistry) on mechanical properties; Lease, Tomblin and Wang have worked together to perform all necessary mechanical testing. The research has been focused on materials that would benefit the High Speed Civil Transport (HSCT) program. The group has visited Dr. Howard Maars and his colleagues at NASA Langley, and has focused their studies on the NASA requirements discussed in this meeting. An important development, requested by NASA scientists, has been the acquisition and study of K3B as a matrix material for the composites. The project has led to the successful acquisition and surface analysis of K3B, together with the successful deposition of this material onto surface oxidized carbon fibers. Mechanical testing, modelling and the construction of composite preparation equipment has been achieved during the grant period.

  17. Metal doped carbon nanoneedles and effect of carbon organization with activity for hydrogen evolution reaction (HER).

    PubMed

    Araujo, Rafael A; Rubira, Adley F; Asefa, Tewodros; Silva, Rafael

    2016-02-10

    Cellulose nanowhiskers (CNW) from cotton, was prepared by acid hydrolysis and purified using a size selection process to obtain homogeneous samples with average particle size of 270 nm and 85.5% crystallinity. Purified CNW was used as precursor to carbon nanoneedles (CNN) synthesis. The synthesis of CNN loaded with different metals dopants were carried out by a nanoreactor method and the obtained CNNs applied as electrocatalysts for hydrogen evolution reaction (HER). In the carbon nanoneedles synthesis, Ni, Cu, or Fe worked as graphitization catalyst and the metal were found present as dopants in the final material. The used metal appeared to have direct influence on the degree of organization of the particles and also in the surface density of polar groups. It was evaluated the influence of the graphitic organization on the general properties and nickel was found as the more appropriate metal since it leads to a more organized material and also to a high activity toward HER.

  18. Inversing grided land surface carbon fluxes focusing on Asia region

    NASA Astrophysics Data System (ADS)

    Zhang, Huifang

    2013-04-01

    With the global carbon budget research carrying out, there is a growing scientific and political interest to better understand terrestrial carbon cycle at global and regional scales. Asia, contributed one of the largest uncertainties to global carbon budget, needs further more investigation and study. The contribution of Asia to the global carbon cycle is characterized by its high fossil fuel emissions due to economic booming and demand steep rising in energy, a rapidly increasing land cover change or degradation caused by population explosion and crop land expansion, a fast forest recovering in virtue of forest afforestation in the past 20 years. These unique characteristics force the exchange of terrestrial carbon more heterogeneous in Asian continent, and lead the Asian carbon balance research's implementation more difficult. In view of the Asian net ecosystem exchange (NEE) of carbon characteristics, we used a state-of-the-art CO2 data assimilation system called CarbonTraker to estimate NEE of CO2 in Asia for every week during the years 2000-2009. This approach includes the following three steps: (1) the atmospheric transport model (TM5) used in the data assimilation system was nested to be 1x1 degree grid in Asian area while globally at 2x3 degree resolution; (2) the number of CO2 observation sites was expend with 22 in Asia (including CONTRAIL and NOAA's CO2 measurement); and (3) two different prior flux products were used to estimate uncertainty ranges. We find the Asian terrestrial biosphere absorbed about 1.89 PgC (1 petagram=1015 g) per year averaged over the period studied, partly offsetting the estimated 3.87 PgC/yr release by fossil fuel burning and cement manufacturing. The estimated sink is located mainly in the boreal Asia, while the temperate Asia and the tropical Asia are a week sink and a very small source, respectively. The results also show that the surface fluxes produced by the CarbonTracker system were reasonably consistent with the recent

  19. High adsorption capacity NaOH-activated carbon for dye removal from aqueous solution.

    PubMed

    Wu, Feng-Chin; Tseng, Ru-Ling

    2008-04-15

    In this study, the surface coverage ratio (Sc/Sp) and monolayer cover adsorption amount per unit surface area (qmon/Sp) were employed to investigate the adsorption isotherm equilibrium of the adsorption of dyes (AB74, BB1 and MB) on NaOH-activated carbons (FWNa2, FWNa3 and FWNa4); the adsorption rate of the Elovich equation (1/b) and the ratio of 1min adsorption amount of adsorbate to the monolayer cover amount of adsorbate (q1/qmon) were employed to investigate adsorption kinetics. The qmon/Sp of NaOH-activated carbons was better than that of KOH-activated carbons prepared from the same raw material (fir wood). The Sc/Sp values of the adsorption of all adsorbates on adsorbent FWNa3 in this study were found to be higher than those in related literature. Parameters 1/b and q1 of the adsorption of dyes on activated carbons in this study were higher than those on KOH-activated carbons; the q1/qmon value of FWNa3 was the highest. The pore structure and the TPD measurement of the surface oxide groups were employed to explain the superior adsorption performance of FWNa3. A high surface activated carbon (FWNa3) with excellent adsorption performance on dyes with relation to adsorption isotherm equilibrium and kinetics was obtained in this study. Several adsorption data processing methods were employed to describe the adsorption performance.

  20. 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...

  1. Molecular simulation study of water--methanol mixtures in activated carbon pores

    SciTech Connect

    Shevade, Abhijit V.; Jiang, Shaoyi; Gubbins, Keith E.

    2000-10-22

    We report a theoretical study of the adsorption behavior of water--methanol mixtures in slit activated carbon micropores. The adsorption isotherms are obtained for a pore of width 2 nm at a temperature of 298 K from grand canonical ensemble Monte Carlo simulations. The water molecules are modeled using the four point transferable intermolecular potential functions (TIP4P) and methanol by the optimized potentials for liquid simulations (OPLS). Carboxyl (COOH) groups are used as active sites on a structured carbon surface. The effect of the relative contributions from dispersion and hydrogen bonding interactions of adsorbates, and of the chemical activation of adsorbents on adsorption behavior is investigated. The adsorption of the mixture components in activated carbon pores occurs by continuous filling, without the sharp capillary condensation observed in graphite pores. Water is preferentially adsorbed over methanol in activated carbon pores for a wide range of pressures, except at lower pressures. The hydrophilic nature of activated carbon pores results in the complexation of both water and methanol molecules with the active sites on the surfaces, leading to bulklike water behavior over the entire pore width. Solvation forces are also calculated as a function of pore size. The negative values found for the solvation force for all pore sizes reflect the hydrophilic interactions of the mixtures with the activated carbon surfaces. {copyright} 2000 American Institute of Physics [S0021-9606(00)51339-7

  2. 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%.

  3. Activated Carbon Fibers For Gas Storage

    SciTech Connect

    Burchell, Timothy D; Contescu, Cristian I; Gallego, Nidia C

    2017-01-01

    The advantages of Activated Carbon Fibers (ACF) over Granular Activated Carbon (GAC) are reviewed and their relationship to ACF structure and texture are discussed. These advantages make ACF very attractive for gas storage applications. Both adsorbed natural gas (ANG) and hydrogen gas adsorption performance are discussed. The predicted and actual structure and performance of lignin-derived ACF is reviewed. The manufacture and performance of ACF derived monolith for potential automotive natural gas (NG) storage applications is reported Future trends for ACF for gas storage are considered to be positive. The recent improvements in NG extraction coupled with the widespread availability of NG wells means a relatively inexpensive and abundant NG supply in the foreseeable future. This has rekindled interest in NG powered vehicles. The advantages and benefit of ANG compared to compressed NG offer the promise of accelerated use of ANG as a commuter vehicle fuel. It is to be hoped the current cost hurdle of ACF can be overcome opening ANG applications that take advantage of the favorable properties of ACF versus GAC. Lastly, suggestions are made regarding the direction of future work.

  4. Surface modification of multiwall carbon nanotubes by sulfonitric treatment

    NASA Astrophysics Data System (ADS)

    Gómez, Sofía; Rendtorff, Nicolás M.; Aglietti, Esteban F.; Sakka, Yoshio; Suárez, Gustavo

    2016-08-01

    Carbon nanotubes are widely used for electronic, mechanical, and optical devices due to their unique structural and quantum characteristics. The species generated by oxidation on the surface of these materials permit binding new reaction chains, which improves the dispersibility, processing and compatibility with other materials. Even though different acid treatments and applications of these CNT have been reported, relatively few research studies have focused on the relationship between the acid treatment and the formation of nanodefects, specific oxidized species or CNT surface defects. In this work, multiwall carbon nanotube (MWCNT) oxidation at 90 °C was characterized in order to determine the acid treatment effect on the surface. It was found that oxidized species are already present in MWCNT without an acid treatment, but there are not enough to cause water-based dispersion. The species were identified and quantified by infrared spectroscopy and X-ray photoelectron spectroscopy. Also, transmission electron microscopy observations showed not only modifications of the oxidized species, but also morphological damage on the surfaces of MWCNT after being subjected to the acid treatment. This effect was also confirmed by Raman spectroscopy. The acid treatment generates higher oxidized species, decreasing the zeta potential in the whole pH range.

  5. Heating effects on modifying carbon surface by reactive plasma

    NASA Astrophysics Data System (ADS)

    Izumi, Yori; Katoh, Masaaki; Ohte, Takeo; Ohtani, Sugio; Kojima, Akira; Saitoh, Naoya

    1996-07-01

    In the surface modification by plasma, surface properties changes with time after the plasma treatment. Such changes should be avoided for practical application. Glassy carbon (GC) was subjected to simultaneous plasma and heat treatments in order to investigate the respective effects. Source gases were tetrafluoromethane (CF 4) and oxygen (O 2). Treatment time and heating temperature of the GC plate were 30 min and 200-500°C, respectively. The surface properties before and after plasma treatment were studied with contact angle measurements and ESCA. When the GC was heated at 400°C during CF 4 plasma treatment, the contact angle after plasma treatment was 133° and constant even after 24 h. At 500°C during O 2 plasma treatment, the contact angle after plasma treatment was 0° and constant even after 24 h. It is found that heating carbon surface during CF 4 or O 2 plasma treatment is effective to stop the change with time after plasma treatment.

  6. Flame retardant polypropylene nanocomposites reinforced with surface treated carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Guleria, Abhishant

    Polypropylene nanocomposites are prepared by reinforcing carbon nanotubes by ex-situ solution mixing method. Interfacial dispersion of carbon nanotubes in polypropylene have been improved by surface modification of CNTs and adding surfactants. Polypropylene nanocomposites fabrication was done after treating CNTs. Firstly, oxidation of CNTs followed by silanization for addition of functionalized groups on the surface of CNTs. Maleic anhydride grafted PPs were used as surfactants. Maleic anhydrides with two different molecular weights were LAMPP and HMAPP. Successful oxidation of CNTs by nitric acid and functionalized CNTs by 3-Aminopropyltriethoxysilane was confirmed by attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) with evidence of absorption peak at 1700 and 1100-1000 cm-1. Scanning electron microscopy (SEM) micrographs revealed that the CNTs dispersion quality was improved by directly adding LMAPP/HMAPP into PP/CNTs system and the PP-CNTs adhesion was enhanced through both the CNTs surface treatment and the addition of surfactant. Thermal gravimetric analysis (TGA) revealed an enhanced thermal stability in the PP/CNTs and PP/CNTs/MAPP. Differential scanning calorimetry (DSC) characterization demonstrated that the crystalline temperature, fusion heat and crystalline fraction of hosting PP were decreased with the introduction of CNTs and surface treated CNTs; however, melting temperature was only slightly changed. Melting rheological behaviors including complex viscosity, storage modulus, and loss modulus indicated significant changes in the PP/MAPP/CNTs system before and after functionalization of CNTs, and the mechanism were also discussed in details.

  7. Electrochemical activation of carbon nanotube/polymer composites.

    PubMed

    Sánchez, Samuel; Fàbregas, Esteve; Pumera, Martin

    2009-01-07

    Electrochemical activation of carbon nanotube/polysulfone composite electrodes for enhanced heterogeneous electron transfer is studied. The physicochemical insight into the electrochemical activation of carbon nanotube/polymer composites was provided by transmission electron microscopy, Raman spectroscopy, electrochemical impedance spectroscopy, and cyclic voltammetry. Dopamine, ascorbic acid, NADH, and ferricyanide are used as a model redox system for evaluating the performance of activated carbon nanotube/polymer composite electrodes. We demonstrate that polymer wrapping of carbon nanotubes is subject to defects and to partial removal during activation. Such tunable activation of electrodes would enable on-demand activation of electrodes for satisfying the needs of sensing or energy storage devices.

  8. Characterization of activated carbon prepared from chlorella-based algal residue.

    PubMed

    Chang, Yuan-Ming; Tsai, Wen-Tien; Li, Ming-Hsuan

    2015-05-01

    The chlorella-based microalgal residue (AR) was tested as a novel precursor for preparing activated carbons. A combined carbonization-activation process with flowing N2 and CO2 gases was used to prepare the carbon materials at the activation temperatures of 800-1000 °C and the residence times of 0-30 min in this work. The elemental contents, pore properties and scanning electron microscopy (SEM) observations of the resulting activated carbons have been performed. The results showed that activation temperature may be the most important parameter for determining their pore properties. The maximal Brunauer-Emmett-Teller (BET) surface area and total pore volume of the resulting activated carbon, which was produced at the activation temperature of 950 °C with the residence time of 30 min, were 840 m(2)/g and 0.46 cm(3)/g, respectively. More interestingly, the resulting activated carbons have significant nitrogen contents of 3.6-9.6 wt%, which make them lower carbon contents (i.e., 54.6-68.4 wt%) than those of commercial activated carbons.

  9. JV Task 119 - Effects of Aging on Treated Activated Carbons

    SciTech Connect

    Edwin Olson; Lucinda Hamre; John Pavlish; Blaise Mibeck

    2009-03-25

    For both the United States and Canada, testing has been under way for electric utilities to find viable and economical mercury control strategies to meet pending future mercury emission limits. The technology that holds the most promise for mercury control in low-chlorine lignite to meet the needs of the Clean Air Act in the United States and the Canada-Wide Standards in Canada is injection of treated activated carbon (AC) into the flue gas stream. Most of the treated carbons are reported to be halogenated, often with bromine. Under a previous multiyear project headed by the Energy & Environmental Research Center (EERC), testing was performed on a slipstream unit using actual lignite-derived flue gas to evaluate various sorbent technologies for their effectiveness, performance, and cost. Testing under this project showed that halogenated ACs performed very well, with mercury capture rates often {ge} 90%. However, differences were noted between treated ACs with respect to reactivity and capacity, possibly as a result of storage conditions. Under certain conditions (primarily storage in ambient air), notable performance degradation had occurred in mercury capture efficiency. Therefore, a small exploratory task within this project evaluated possible differences resulting from storage conditions and subsequent effects of aging that might somehow alter their chemical or physical properties. In order to further investigate this potential degradation of treated (halogenated) ACs, the EERC, together with DOE's National Energy Technology Laboratory, the North Dakota Industrial Commission (NDIC), the Electric Power Research Institute (EPRI), SaskPower, and Otter Tail Power Company, assessed the aging effects of brominated ACs for the effect that different storage durations, temperatures, and humidity conditions have on the mercury sorption capacity of treated ACs. No aging effects on initial capture activity were observed for any carbons or conditions in the investigation

  10. Remediation of organochlorine pesticides contaminated lake sediment using activated carbon and carbon nanotubes.

    PubMed

    Hua, Shan; Gong, Ji-Lai; Zeng, Guang-Ming; Yao, Fu-Bing; Guo, Min; Ou, Xiao-Ming

    2017-06-01

    Organochlorine pesticides (OCPs) in sediment were a potential damage for humans and ecosystems. The aim of this work was to determine the effectiveness of carbon materials remedy hexachlorocyclohexane (HCH) and dichlorodiphenyltrichloroethanes (DDTs) in sediment. Two different carbon materials including activated carbon (AC) and multi-walled carbon nanotubes (MWCNTs) were used in the present research. Sediment treated with 2 wt% AC and MWCNTs after 150 d contact showed 97%, and 75% reduction for HCH, and 93% and 59% decrease for DDTs in aqueous equilibrium concentration, respectively. Similarly, the reduction efficiencies of DDT and HCH uptake by semipermeable membrane devices (SPMDs) treated with AC (MWCNTs) were 97% (75%) and 92% (63%), respectively under the identical conditions. Furthermore, for 2 wt% AC (MWCNTs) system, a reduction of XAD beads uptake up to 87% (52%) and 73% (67%) was obtained in HCH and DDT flux to overlying water in quiescent system. Adding MWCNTs to contaminated sediment did not significantly decrease aqueous equilibrium concentration and DDTs and HCH availability in SPMDs compared to AC treatment. A series of results indicated that AC had significantly higher remediation efficiency towards HCH and DDTs in sediment than MWCNTs. Additionally, the removal efficiencies of two organic pollutants improved with increasing material doses and contact times. The greater effectiveness of AC was attributed to its greater specific surface area, which was favorable for binding contaminants. These results highlighted the potential for using AC as in-situ sorbent amendments for sediment remediation.

  11. Platinum electrode modification: Unique surface carbonization approach to improve performance and sensitivity.

    PubMed

    Lee, Hwi Yong; Barber, Cedrick; Minerick, Adrienne R

    2015-08-01

    Many microfluidic devices, also known as lab-on-a-chip devices, employ electrochemical detection methods using microelectrodes. Miniaturizing electrodes inevitably reduces electrode sensitivity and decreases the S/N, which limits applications within microfluidic devices. However, microelectrode surface modification can increase the surface area and sensitivity. In the present work, we report substantial improvement in platinum electrode performance and sensitivity by coating with carbon from red blood cells. The larger goal of this work was to measure DC electrical resistances of red blood cell suspensions in a microchannel for hematocrit determination. It was observed that as current responses of red blood cell suspensions were measured, the platinum electrode performance (reproducibility and S/N) improved with time. The platinum electrode electrocatalytic activity for red blood cell current measurements improved by 140%. Systematic experimentation revealed that red blood cells adsorb and carbonize the platinum electrode surfaces. The electrode surfaces before and after performance improvements were analyzed by field emission scanning electron microscopy, energy dispersive spectrometry, and Raman spectrometry. The formed carbon layers on the electrode surfaces were found to be proteomic and increased surface area with a porous three-dimensional structure, thus improving performance and stabilizing currents.

  12. One-Pot synthesis of phosphorylated mesoporous carbon heterogeneous catalysts with tailored surface acidity

    SciTech Connect

    Fulvio, Pasquale F; Mahurin, Shannon Mark; Mayes, Richard T; Bauer, Christopher; Wang, Xiqing; Veith, Gabriel M; Dai, Sheng

    2012-01-01

    Soft-templated phosphorylated mesoporous carbons with homogeneous distributions of phosphate groups were prepared by a 'one-pot' synthesis method using mixtures of phosphoric acid with hydrochloric, or nitric acids in the presence of Pluronic F127 triblock copolymer. Adjusting the various ratios of phosphoric acid used in these mixtures resulted in carbons with distinct adsorption, structural and surface acidity properties. The pore size distributions (PSDs) from nitrogen adsorption at -196 C showed that mesoporous carbons exhibit specific surface areas as high as 551 m{sup 2}/g and mesopores as large as 13 nm. Both structural ordering of the mesopores and the final phosphate contents were strongly dependent on the ratios of H{sub 3}PO{sub 4} in the synthesis gels, as shown by transmission electron microscopy (TEM), X-ray photoelectron (XPS) and energy dispersive X-ray spectroscopy (EDS). The number of surface acid sites determined from temperature programmed desorption of ammonia (NH{sub 3}-TPD) were in the range of 0.3-1.5 mmol/g while the active surface areas are estimated to comprise 5-54% of the total surface areas. Finally, the conversion temperatures for the isopropanol dehydration were lowered by as much as 100 C by transitioning from the least acidic to the most acidic catalysts surface.

  13. Physical and chemical properties of selected agricultural byproduct-based activated carbons and their ability to adsorb geosmin.

    PubMed

    Ng, Chilton; Losso, Jack N; Marshall, Wayne E; Rao, Ramu M

    2002-09-01

    The objectives of this study were to evaluate selected physical and chemical properties of agricultural byproduct-based activated carbons made from pecan shells and sugarcane bagasse, and compare those properties to a commercial coal-based activated carbon as well as to compare the adsorption efficiency of these carbons for geosmin. Comparison of the physical and chemical properties of pecan shell- and bagasse-based carbons to the commercial carbon, Calgon Filtrasorb 400, showed that pecan shell carbon, but not the bagasse carbon, compared favorably to Filtrasorb 400, especially in terms of surface area, bulk density, ash and attrition. A carbon dosage study done in a model system showed the amount of geosmin adsorbed to be greater for Filtrasorb 400 and the bagasse-based carbon at low carbon concentrations than for the pecan shell carbons, but geosmin adsorption was similar in all carbons at higher carbon dosages. Application of the Freundlich isotherm model to the adsorption data showed that carbons made by steam activation of pecan shells or sugarcane bagasse had geosmin adsorption characteristics most like those of the commercial carbon. In terms of physical, chemical and adsorptive properties, steam-activated pecan shell carbon most resembled the commercial carbon and has the potential to replace Filtrasorb 400 in applications involving removal of geosmin from aqueous environments.

  14. Activated carbon fiber for heterogeneous activation of persulfate: implication for the decolorization of azo dye.

    PubMed

    Chen, Jiabin; Hong, Wei; Huang, Tianyin; Zhang, Liming; Li, Wenwei; Wang, Ying

    2016-09-01

    Activated carbon fiber (ACF) was used as a green catalyst to activate persulfate (PS) for oxidative decolorization of azo dye. ACF demonstrated a higher activity than activated carbon (AC) to activate PS to decolorize Orange G (OG). The decolorization efficiency of OG increased as ACF loading, PS dosage, and temperature increased. OG decolorization followed a pseudo first-order kinetics, and the activation energy was 40.902 kJ/mol. pH had no apparent effect on OG decolorization. Radical quenching experiments with various radical scavengers (e.g., alcohols, phenol) showed that radical-induced decolorization of OG took place on the surface of ACF, and both SO4 (·-) and HO· were responsible for OG decolorization. The impact of inorganic salts was also evaluated because they are important compositions of dye wastewater. Cl(-) and SO4 (2-) exhibited a promoting effect on OG decolorization, and the accelerating rate increased with elevating dosage of ions. Addition of Cl(-) and SO4 (2-) could increase the adsorption of OG on ACF surface, thus favorable for OG decolorization caused by the surface-bound SO4 (·-) and HO·. Conversely, HCO3 (-) and humic acid (HA) slightly inhibited OG decolorization. The azo band and naphthalene ring on OG were remarkably destructed to other intermediates and finally mineralized to CO2 and H2O.

  15. Friction, wear, and transfer of carbon and graphite to copper, chromium, and aluminum metal surfaces in vacuum

    NASA Technical Reports Server (NTRS)

    Buckley, D. H.

    1973-01-01

    Sliding friction experiments were conducted with amorphous and fully graphitized carbons sliding on copper and on films of chromium and aluminum on copper. Auger emission spectroscopy analysis was used to monitor carbon transfer to the metal surfaces. Friction and wear were also measured. Metal surfaces were examined both in the clean state and with normal oxides present. Results indicate that different metals have an important effect on friction, wear, and transfer characteristics. With amorphous carbon, the least chemically active metal gave the highest wear and amount of carbon transfer. Both forms of carbon gave lower friction and wear and lower transfer rates when in contact with clean, as opposed to oxide-covered, chromium surfaces. With copper, the reverse was true; cleaning was detrimental.

  16. Photocatalytic activity and characterization of sol-gel-derived Ni-doped TiO2-coated active carbon composites

    NASA Astrophysics Data System (ADS)

    Bhosale, R. R.; Pujari, S. R.; Lande, M. K.; Arbad, B. R.; Pawar, S. B.; Gambhire, A. B.

    2012-11-01

    Ni-doped, TiO2-coated active carbon (Ni-TiO2/AC) were prepared by a sol-gel method. The effect of supports, including TiO2 and active carbon (AC), on the molecular structure and photocatalytic activity of nickel oxide for complete decomposition of methylene blue has been examined with respect to the content of Ni on the catalyst surface. The photocatalytic activities of the Ni-TiO2/AC composites were evaluated in the decomposition of methylene blue solution under visible-light irradiation. The results indicate that Ni-TiO2/AC has a higher efficiency in decomposition of methylene blue than TiO2 and TiO2/AC. This was attributed to the different functions of active carbon and nickel species. First, nanosize TiO2 particles on composites were not reunited, possible because active carbon retards transformation of anatase into rutile and decrease the crystallite size. Second, production of high concentrations of organic compound near Ni-TiO2. Third, carbon in active carbon causes some of the TiO2 to reduce to Ti3+ ions, which prevents electron-hole pair recombination. It was found that the addition of Ni to TiO2 sol could suppress the grain growth of TiO2 crystals and increase the hydroxyl content on the surface of TiO2/AC. The photocatalytic efficiency and activity of the composites remained good, even after three cycles.

  17. Chemically activated carbon from lignocellulosic wastes for heavy metal wastewater remediation: Effect of activation conditions.

    PubMed

    Nayak, Arunima; Bhushan, Brij; Gupta, Vartika; Sharma, P

    2017-05-01

    Chemical activation is known to induce specific surface features of porosity and functionality which play a definite role in enhancing the adsorptive potential of the developed activated carbons. Different conditions of temperature, time, reagent type and impregnation ratio were applied on sawdust precursor and their effect on the physical, surface chemical features and finally on the adsorption potential of the developed activated carbons were analysed. Under activation conditions of 600°C, 1hr, 1:0.5 ratio, ZnCl2 impregnated carbon (CASD_ZnCl2) resulted in microporosity while KOH impregnation (CASD_KOH) yielded a carbon having a wider pore size distribution. The surface chemistry revealed similar functionalities. At same pH, temperature and adsorbate concentrations, CASD_KOH demonstrated better adsorption potential (1.06mmoles/g for Cd(2+) and 1.61mmoles/g for Ni(2+)) in comparison to CASD_ZnCl2 (0.23mmoles/g and 0.33mmoles/g for Cd(2+) and Ni(2+) respectively). Other features were a short equilibrium time of 60mins and an adsorbent dose of 0.2g/L for the CASD_KOH in comparison to CASD_ZnCl2 (equilibrium time of 150min and dosage of 0.5g/L). The nature of interactions was physical for both adsorbents and pore diffusion mechanisms were operative. The results reveal the potentiality of chemical activation so as to achieve the best physico-chemical properties suited for energy efficient, economical and eco-friendly water treatment.

  18. Catalytic oxidation ofS(IV) on activated carbon in aqueous suspension: kinetics and mechanism

    SciTech Connect

    Brodzinsky, R.

    1981-02-01

    Activated carbon and combustion produced soot particles have been studied for their catalytic effect on the oxidation of aqueous sulfur(IV) species. Detailed kinetic studies of the reaction were performed on three different activated carbons and on a soot collected in a highway tunnel. Combustion produced soots were tested for their catalytic behavior and found to be similar to the activated carbons. The reaction rate was found to be linearly dependent on the concentration of carbon particles in the solution. The rate was found to follow a Langmuir adsorption isotherm for its dependence on oxygen and the product of two adsorption isotherms for S(IV). The reaction is independent of the pH of the solution when the pH is below 7.6. The reaction does not occur when the pH is above 7.6. The three aqueous S(IV) species are catalyzed in their oxidation by the carbon particles in a similar manner. Activation energies for the reactions on the different carbons are all about 8.5 kcal/mole. A possible four-step reaction mechanism is proposed. It consists of the adsorption of a dissolved oxygen molecule onto the carbon surface, followed by the adsorption of two S(IV) molecules or ions. These are oxidized on the surface to sulfate, which desorbs from the surface, regenerating the catalytically active site.

  19. Coupling template nanocasting and self-activation for fabrication of nanoporous carbon

    PubMed Central

    Kong, Lingjun; Liu, Mingxiang; Diao, Zenghui; Chen, Diyun; Chang, Xiangyang; Xiong, Ya

    2016-01-01

    Hierarchical nanoporous carbon (NPC) with great surface area and developed pore size distribution has been intently concerned. Herein, we report a facile method coupling template nanocasting and self-activation to fabricate nanoporous carbon with continuous micro, meso and macro pores, in which CaCO3 acted as template and activation reagent while the flour was the carbon precursor. Effects of mass ratio of CaCO3 to flour and carbonized temperature on the pore structures of NPC were investigated by nitrogen adsorption-desorption isotherms and SEM analysis. Another kind of carbon was prepared by directly mixed powder CaCO3 with flour carbonized at 800 °C (NPC-p) to comparatively investigate the pore fabricating mechanism. Results shown that carbonized at 800 °C was favorable to fabricate the continuous macro, meso and micro pores. The resulted NPC in a mass ratio of 1 to 2 had the considerable SBET and VT of 575.4 m2/g and 0.704 cm3/g, respectively. Only surface activation was observed for NPC-p. Nanocasting of the powder CaCO3 contributed to fabricate macropores and the CO2 activation contributed to meso- and micropores. Coupling activation and nanocasting effect due to the decomposition of CaCO3 template into CO2 and CaO was ascribed to synthesize the nanoporous carbon. PMID:27901109

  20. Coupling template nanocasting and self-activation for fabrication of nanoporous carbon

    NASA Astrophysics Data System (ADS)

    Kong, Lingjun; Liu, Mingxiang; Diao, Zenghui; Chen, Diyun; Chang, Xiangyang; Xiong, Ya

    2016-11-01

    Hierarchical nanoporous carbon (NPC) with great surface area and developed pore size distribution has been intently concerned. Herein, we report a facile method coupling template nanocasting and self-activation to fabricate nanoporous carbon with continuous micro, meso and macro pores, in which CaCO3 acted as template and activation reagent while the flour was the carbon precursor. Effects of mass ratio of CaCO3 to flour and carbonized temperature on the pore structures of NPC were investigated by nitrogen adsorption-desorption isotherms and SEM analysis. Another kind of carbon was prepared by directly mixed powder CaCO3 with flour carbonized at 800 °C (NPC-p) to comparatively investigate the pore fabricating mechanism. Results shown that carbonized at 800 °C was favorable to fabricate the continuous macro, meso and micro pores. The resulted NPC in a mass ratio of 1 to 2 had the considerable SBET and VT of 575.4 m2/g and 0.704 cm3/g, respectively. Only surface activation was observed for NPC-p. Nanocasting of the powder CaCO3 contributed to fabricate macropores and the CO2 activation contributed to meso- and micropores. Coupling activation and nanocasting effect due to the decomposition of CaCO3 template into CO2 and CaO was ascribed to synthesize the nanoporous carbon.

  1. Surface diffusion of a carbon adatom on charged SWCNT

    NASA Astrophysics Data System (ADS)

    Han, Longtao; Krstic, Predrag; Kaganovich, Igor

    2016-09-01

    Diffusion of a carbon adatom on SWCNT could be a mechanism for a CNT growth in a volume plasma, supplementing its growth from a transition metal catalyst nanoparticle. However, being embedded in plasma, the nanotube can charge by the plasma particles irradiation, in particular by electrons. Using Density Functional Theory, Nudged Elastic Band and Kinetic Monte Carlo methods we find (1) equilibrium sites, (2) adsorption energies, (3) potential barriers, (4) vibrational frequencies and (5) most probable pathways for diffusion of the adatom on external surfaces of SWCNTs of (5,5), (10,0) and (10,5) chirality, as function of its charge. The metal (5,5) SWCNT can support a fast diffusion of the carbon adatom, which is accelerated by the presence of the SWCNT negative charge. Reduced model of SWCNT growth is proposed. This work was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division.

  2. X-ray photoemission analysis of clean and carbon monoxide-chemisorbed platinum(111) stepped surfaces using a curved crystal

    PubMed Central

    Walter, Andrew L.; Schiller, Frederik; Corso, Martina; Merte, Lindsay R.; Bertram, Florian; Lobo-Checa, Jorge; Shipilin, Mikhail; Gustafson, Johan; Lundgren, Edvin; Brión-Ríos, Anto´n X.; Cabrera-Sanfelix, Pepa; Sánchez-Portal, Daniel; Ortega, J. Enrique

    2015-01-01

    Surface chemistry and catalysis studies could significantly gain from the systematic variation of surface active sites, tested under the very same conditions. Curved crystals are excellent platforms to perform such systematics, which may in turn allow to better resolve fundamental properties and reveal new phenomena. This is demonstrated here for the carbon monoxide/platinum system. We curve a platinum crystal around the high-symmetry (111) direction and carry out photoemission scans on top. This renders the spatial core-level imaging of carbon monoxide adsorbed on a ‘tunable' vicinal surface, allowing a straightforward visualization of the rich chemisorption phenomenology at steps and terraces. Through such photoemission images we probe a characteristic elastic strain variation at stepped surfaces, and unveil subtle stress-release effects on clean and covered vicinal surfaces. These results offer the prospect of applying the curved surface approach to rationally investigate the chemical activity of surfaces under real pressure conditions. PMID:26561388

  3. X-ray photoemission analysis of clean and carbon monoxide-chemisorbed platinum(111) stepped surfaces using a curved crystal

    DOE PAGES

    Walter, Andrew L.; Schiller, Frederik; Corso, Martina; ...

    2015-11-12

    Surface chemistry and catalysis studies could significantly gain from the systematic variation of surface active sites, tested under the very same conditions. Curved crystals are excellent platforms to perform such systematics, which may in turn allow to better resolve fundamental properties and reveal new phenomena. This is demonstrated here for the carbon monoxide/platinum system. We curve a platinum crystal around the high-symmetry (111) direction and carry out photoemission scans on top. This renders the spatial core-level imaging of carbon monoxide adsorbed on a 'tunable' vicinal surface, allowing a straightforward visualization of the rich chemisorption phenomenology at steps and terraces. Throughmore » such photoemission images we probe a characteristic elastic strain variation at stepped surfaces, and unveil subtle stress-release effects on clean and covered vicinal surfaces. Lastly, these results offer the prospect of applying the curved surface approach to rationally investigate the chemical activity of surfaces under real pressure conditions.« less

  4. X-ray photoemission analysis of clean and carbon monoxide-chemisorbed platinum(111) stepped surfaces using a curved crystal

    SciTech Connect

    Walter, Andrew L.; Schiller, Frederik; Merte, Lindsay R.; Bertram, Florian; Lobo-Checa, Jorge; Gustafson, Johan; Lundgren, Edvin; Brión-Ríos, Anto´n X.; Cabrera-Sanfelix, Pepa; Sánchez-Portal, Daniel

    2015-11-12

    Surface chemistry and catalysis studies could significantly gain from the systematic variation of surface active sites, tested under the very same conditions. Curved crystals are excellent platforms to perform such systematics, which may in turn allow to better resolve fundamental properties and reveal new phenomena. This is demonstrated here for the carbon monoxide/platinum system. We curve a platinum crystal around the high-symmetry (111) direction and carry out photoemission scans on top. This renders the spatial core-level imaging of carbon monoxide adsorbed on a 'tunable' vicinal surface, allowing a straightforward visualization of the rich chemisorption phenomenology at steps and terraces. Through such photoemission images we probe a characteristic elastic strain variation at stepped surfaces, and unveil subtle stress-release effects on clean and covered vicinal surfaces. Lastly, these results offer the prospect of applying the curved surface approach to rationally investigate the chemical activity of surfaces under real pressure conditions.

  5. Synthesis of a high-yield activated carbon by air gasification of macadamia nut shell charcoal

    SciTech Connect

    Dai, X.; Antal, M.J. Jr.

    1999-09-01

    Macadamia nut shell charcoal was heated in an inert environment to temperatures above 1000 K (carbonized), reacted with oxygen (Po{sub 2} = 2.68--11.3 kPa) at temperatures between 525 and 586 K (oxygenated), and heated again in an inert environment to temperatures above 1000 K (activated) to produce an activated carbon. Carbons produced by this process possess surface areas and iodine numbers in the range of 400--550. Overall yields of these carbons (based on the dry, raw macadamia nut shell feed) ranged from 24 to 30 wt %. Under the conditions employed in this work, the rates of chemisorption and gasification were not mass transfer limited. Initially, the gasification reaction was first-order with respect to oxygen concentration but became independent of oxygen concentration as the surface sites of the carbon became saturated with oxygen.

  6. SO{sub 2} oxidation in a periodically operated trickle bed: Comparison of activated carbon catalysts

    SciTech Connect

    Lee, Joong Kee; Hudgins, R.R.; Silveston, P.L.

    1996-12-31

    Catalytic activities of two different activated carbons, BPL{trademark} and Centaur{trademark} catalysts (Calgon Carbon Corp.), were compared in a periodically operated trickle-bed reactor for SO{sub 2} oxidation by varying the cycle period and split. In an effort to characterize the carbon surface, differential thermogravimetric analysis and TPD were used to observe oxygen functional groups. The Centaur catalyst, which appears to have a more suitable density of oxygen functional groups, has the higher catalytic activity for SO{sub 2} oxidation. 8 refs., 8 figs., 1 tab.

  7. Active micromixer using surface acoustic wave streaming

    SciTech Connect

    Branch; Darren W. , Meyer; Grant D. , Craighead; Harold G.

    2011-05-17

    An active micromixer uses a surface acoustic wave, preferably a Rayleigh wave, propagating on a piezoelectric substrate to induce acoustic streaming in a fluid in a microfluidic channel. The surface acoustic wave can be generated by applying an RF excitation signal to at least one interdigital transducer on the piezoelectric substrate. The active micromixer can rapidly mix quiescent fluids or laminar streams in low Reynolds number flows. The active micromixer has no moving parts (other than the SAW transducer) and is, therefore, more reliable, less damaging to sensitive fluids, and less susceptible to fouling and channel clogging than other types of active and passive micromixers. The active micromixer is adaptable to a wide range of geometries, can be easily fabricated, and can be integrated in a microfluidic system, reducing dead volume. Finally, the active micromixer has on-demand on/off mixing capability and can be operated at low power.

  8. Recent Data Analysis of Carbon ACtivation

    NASA Astrophysics Data System (ADS)

    Jiang, Hui Ming; Smith, Elizabeth; Padalino, Stephen; Baumgart, Leigh; Suny Geneseooltz, Katie; Colburn, Robyn; Fuschino, Julia

    2002-10-01

    A method for measuring tertiary neutrons produced in Inertial Confinement Fusion reactions has been developed using carbon activation. Ultra pure samples of carbon, free from positron-emitting contaminants must be used in the detection. Our primary goal has been to reduce the contamination level by refining purification and packaging procedures. This process involves baking the disks in a vacuum oven to 1000¢XC @ 200 microns for a prescribed bake time without exposing the disks to nitrogen in the air which is a major contaminant. Recent experiments were conducted to determine the optimal bake time for purification. Disks were baked for varying times, from one hour to five hours, and then exposed to high-neutron-yield ( 5 x 1013) shots on OMEGA. Data collected was normalized to the same time interval and the same primary neutron yield, and no significant difference in the number of background counts was seen. Experimental results also indicated that disks that were exposed to air for short time intervals showed a significant increase in the number of contamination counts. This further supports our findings that the gaseous diffusion through graphite disks is very high. Experimental results of these findings will be presented. Research funded in part by the United States Department of Energy.

  9. 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.

  10. Cellulose: A review as natural, modified and activated carbon adsorbent.

    PubMed

    Suhas; Gupta, V K; Carrott, P J M; Singh, Randhir; Chaudhary, Monika; Kushwaha, Sarita

    2016-09-01

    Cellulose is a biodegradable, renewable, non-meltable polymer which is insoluble in most solvents due to hydrogen bonding and crystallinity. Natural cellulose shows lower adsorption capacity as compared to modified cellulose and its capacity can be enhanced by modification usually by chemicals. This review focuses on the utilization of cellulose as an adsorbent in natural/modified form or as a precursor for activated carbon (AC) for adsorbing substances from water. The literature revealed that cellulose can be a promising precursor for production of activated carbon with appreciable surface area (∼1300m(2)g(-1)) and total pore volume (∼0.6cm(3)g(-1)) and the surface area and pore volume varies with the cellulose content. Finally, the purpose of review is to report a few controversies and unresolved questions concerning the preparation/properties of ACs from cellulose and to make aware to readers that there is still considerable scope for future development, characterization and utilization of ACs from cellulose.

  11. Adsorption of radon and water vapor on commercial activated carbons

    SciTech Connect

    Hassan, N.M.; Ghosh, T.K.; Hines, A.L.; Loyalka, S.K.

    1995-02-01

    Equilibrium adsorption isotherms are reported for radon and water vapor on two commercial activated carbons: coconut shell Type PCB and hardwood Type BD. The isotherms of the water vapor were measured gravimetrically at 298 K. The isotherms of radon from dry nitrogen were obtained at 293, 298, and 308 K while the data for the mixture of radon and water vapor were measured at 298 K. The concentrations of radon in the gas and solid phases were measured simultaneously, once the adsorption equilibrium and the radioactive equilibrium between the radon and its daughter products were established. The shape of the isotherms was of Type III for the radon and Type V for the water vapor, according to Brunauer`s classification. The adsorption mechanism was similar for both the radon and the water vapor, being physical adsorption on the macropore surface area in the low pressure region and micropore filling near saturation pressure. The uptake capacity of radon decreased both with increasing temperature and relative humidity. The heat of adsorption data indicated that the PCB- and the BD-activated carbons provided a heterogeneous surface for radon adsorption. The equilibrium data for radon were correlated with a modified Freundlich equation.

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

    PubMed

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

    2017-03-01

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