Note: This page contains sample records for the topic activated carbon process from Science.gov.
While these samples are representative of the content of Science.gov,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of Science.gov
to obtain the most current and comprehensive results.
Last update: November 12, 2013.
1

Production of activated carbons from waste tire – process design and economical analysis  

Microsoft Academic Search

The process design and economic analysis of process plants to produce activated carbons from waste tires and coal have been performed. The potential range of products from each process has been considered, namely for waste tire – pyro-gas, active carbon, carbon black and pyro-oil; for coal – pyro-gas and active carbons. Sensitivity analyses have been carried out on the main

Danny C. K. Ko; Edward L. K. Mui; Ken S. T. Lau; Gordon McKay

2004-01-01

2

Concurrent Removal of Toxic Heavy Metals and Organic Substances by Activated Carbon Process from Contaminated Groundwater.  

National Technical Information Service (NTIS)

The treatability of groundwater containing both toxic heavy metals and organic substances was performed in the laboratory using synthetic solutions and activated carbon adsorption process. Two typical activated carbons, i.e., Nuchar SA (an L-type) and Fil...

C. P. Huang

1984-01-01

3

Biofilm processes in biologically active carbon water purification  

Microsoft Academic Search

This review paper serves to describe the composition and activity of a biologically active carbon (BAC) biofilm used in water purification. An analysis of several physical–chemical, biochemical and microbiological methods (indicators) used to characterize the BAC biofilm's composition and activity is provided. As well, the ability of the biofilm to remove and biodegrade waterborne organic substances and pollutants will be

David R. Simpson

2008-01-01

4

ACTIVATED CARBON PROCESS FOR THE TREATMENT OF CADMIUM(II)-CONTAINING WASTEWATERS  

EPA Science Inventory

The removal of cadmium(II) from two synthetic cadmium plating wastewaters by an activated carbon adsorption process has been investigated. Among the 17 different types of activated carbon tested, it was found that the acidic activated carbons, namely Nuchar SA and Nuchar SN exhib...

5

Polymer flotation and activated carbon adsorption treatment for in situ tar sand process water  

Microsoft Academic Search

Process waters collected during a Department of Energy's in situ tar sand extraction experiment near Vernal, Utah were treated by polymer assisted induced air flotation and activated carbon adsorption. The flotation process removed over 99 percent of the organic load as emulsified bitumen but did little to reduce residual toxicity in the effluents. Activated carbon adsorption was needed to remove

W. F. McTernan; W. E. Blanton; G. D. Boardman; B. T. Nolan; D. J. Kocornik

1986-01-01

6

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

PubMed

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 128.21mgg(-1) and carbon content 76.29%, while the BET surface area and total pore volume corresponded to 801.5m(2)g(-1) and 0.393cm(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. PMID:24080293

Ang?n, Dilek; Altintig, Esra; Köse, Tijen Ennil

2013-09-08

7

SYSTEMATIC SCANNING ELECTRON MICROSCOPY FOR EVALUATING COMBINED BIOLOGICAL/GRANULAR ACTIVATED CARBON TREATMENT PROCESSES  

EPA Science Inventory

A semi-quantitative scanning electron microscope (SEK) analytical technique has been developed to examine granular activated carbon (GAC) utilized as media for biomass attachment in liquid waste treatment (combined processes). he procedure allows for the objective monitoring, com...

8

DEVELOPMENT OF THE WESTVACO ACTIVATED CARBON PROCESS FOR SOX RECOVERY AS ELEMENTAL SULFUR. VOLUME II. APPENDIX  

EPA Science Inventory

The report gives results of a demonstration (in a 20,000-cfh integral pilot plant) of an all-dry, fluidized-bed process, using activated carbon for recovering SO2 as elemental sulfur. Granular carbon was recycled continuously more than 20 times between contact with flue gas from ...

9

DEVELOPMENT OF THE WESTVACO ACTIVATED CARBON PROCESS FOR SOX RECOVERY AS ELEMENTAL SULFUR. VOLUME I  

EPA Science Inventory

The report gives results of a demonstration (in a 20,000-cfh integral pilot plant) of an all-dry, fluidized-bed process, using activated carbon for recovering SO2 as elemental sulfur. Granular carbon was recycled continuously more than 20 times between contact with flue gas from ...

10

Production of activated carbons from waste tire--process design and economical analysis.  

PubMed

The process design and economic analysis of process plants to produce activated carbons from waste tires and coal have been performed. The potential range of products from each process has been considered, namely for waste tire--pyro-gas, active carbon, carbon black and pyro-oil; for coal--pyro-gas and active carbons. Sensitivity analyses have been carried out on the main process factors; these are product price, production capacity, total production cost, capital investment and the tipping fee. Net present values for the two plants at various discount factors have been determined and the internal rates of return have been determined as 27.4% and 18.9% for the waste tire plant and the coal plant, respectively. PMID:15504665

Ko, Danny C K; Mui, Edward L K; Lau, Ken S T; McKay, Gordon

2004-01-01

11

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

Microsoft Academic Search

Supercritical fluid technique have been exploited in extraction, separation and crystallization processes. In the field of pharmaceutics, supercritical carbon dioxide (scCO2) has been used for the purpose of micronization, polymorphic control, and preparation of solid dispersion and complexes. Particle design of active pharmaceutical ingredients is important to make the solid dosage forms with suitable physicochemical properties. Control of the characteristic

Kunikazu Moribe; Yuichi Tozuka; Keiji Yamamoto

2008-01-01

12

Kinetics of reactive azo-dye decolorization by Pseudomonas luteola in a biological activated carbon process  

Microsoft Academic Search

A laboratory-scale biological activated carbon (BAC) process was conducted to treat a reactive azo-dye (reactive red 22) by Pseudomonas luteola and the kinetics of azo-dye decolorization was investigated. The BAC-reactor removed 89% of reactive red 22 while P. luteola biofilm and suspended P. luteola reached a maximum growth rate at a steady-state condition. The azo-dye effluent from BAC-reactor met a

Yen-Hui Lin; Jyh-Yih Leu

2008-01-01

13

Synergetic effects for p-nitrophenol abatement using a combined activated carbon adsorption-electrooxidation process  

Microsoft Academic Search

A novel fluidized electrochemical reactor that integrated advanced electrochemical oxidation with activated carbon (AC) fluidization in a single cell was developed to model pollutant p-nitrophenol (PNP) abatement. AC fluidization could enhance COD removal by 22%?30%. In such a combined process, synergetic effects on PNP and COD removal was found, with their removal rate being enhanced by 137.8% and 97.8%, respectively.

ZHOU Ming-hua; DAI Qi-zhou; LEI Le-cheng; WANG Da-hui

14

Synergetic effects for p -nitrophenol abatement using a combined activated carbon adsorption-electrooxidation process  

Microsoft Academic Search

A novel fluidized electrochemical reactor that integrated advanced electrochemical oxidation with activated carbon (AC) fluidization\\u000a in a single cell was developed to model pollutant p-nitrophenol (PNP) abatement. AC fluidization could enhance COD removal by 22%–30%. In such a combined process, synergetic\\u000a effects on PNP and COD removal was found, with their removal rate being enhanced by 137.8% and 97.8%, respectively.

Ming-hua Zhou; Qi-zhou Dai; Le-cheng Lei; Da-hui Wang

2004-01-01

15

Powdered activated carbon augmented double react-settle sequencing batch reactor process for treatment of landfill leachate  

Microsoft Academic Search

Three types of sequencing batch reactors (SBRs) were used in the treatment of landfill leachate in Kulim, Malaysia. These SBRs were a non-powdered activated carbon SBR (NPAC-SBR), powdered activated carbon SBR (PAC-SBR), and double react-settle SBR (DRS-SBR). Powdered activated carbon was used to augment the SBR process in the PAC and DRS reactors. The first two reactors operate on five

Shuokr Qarani Aziz; Hamidi Abdul Aziz; Mohd Suffian Yusoff

2011-01-01

16

[Water quality safety of ozonation and biologically activated carbon process in application].  

PubMed

Ozonation and biologically activated carbon process, one of advanced treatment technologies, has been applied in many places at home and abroad. However, some emerging water quality problems appeared in operation. Drinking water treatment plant (6 x 10(5) m3/d) with ozonation and biologically activated carbon process (O3-BAC process) was investigated systematically, including microbial safety, the excessive growth of aquatic microorganism and chemical stability of water quality. And some experiments were done in the pilot plant (10 m3/h) at the same time. O3-BAC process is reliable in microbial safety, but operation management should be enhanced. A good number of aquatic microorganisms grow immoderately during operation of O3-BAC process, which is more serious especially in place with high temperature and humidity. With prolong of runtime, the growth of aquatic microorganisms varies regularly. That is hazardous to water quality safety. When raw water is low with alkalinity, decrease of pH in O3-BAC process is obvious. That will seriously affect on chemical stability. PMID:20063746

Qiao, Tie-Jun; Zhang, Xi-Hui

2009-11-01

17

Synergetic effects for p-nitrophenol abatement using a combined activated carbon adsorption-electrooxidation process.  

PubMed

A novel fluidized electrochemical reactor that integrated advanced electrochemical oxidation with activated carbon (AC) fluidization in a single cell was developed to model pollutant p-nitrophenol (PNP) abatement. AC fluidization could enhance COD removal by 22%-30%. In such a combined process, synergetic effects on PNP and COD removal was found, with their removal rate being enhanced by 137.8% and 97.8%, respectively. AC could be electrochemically regenerated and reused, indicating the combined process would be promising for treatment of biorefractory organic pollutants. PMID:15547957

Zhou, Min-Hua; Dai, Qi-Zhou; Lei, Le-Cheng; Wang, Da-Hui

2004-12-01

18

Preparation of sulfurized powdered activated carbon from waste tires using an innovative compositive impregnation process.  

PubMed

The objective of this study is to develop an innovative compositive impregnation process for preparing sulfurized powdered activated carbon (PAC) from waste tires. An experimental apparatus, including a pyrolysis and activation system and a sulfur (S) impregnation system, was designed and applied to produce sulfurized PAC with a high specific surface area. Experimental tests involved the pyrolysis, activation, and sulfurization of waste tires. Waste-tire-derived PAC (WPAC) was initially produced in the pyrolysis and activation system. Experimental results indicated that the Brunauer-Emmett-Teller (BET) surface area of WPAC increased, and the average pore radius of WPAC decreased, as water feed rate and activation time increased. In this study, a conventional direct impregnation process was used to prepare the sulfurized PAC by impregnating WPAC with sodium sulfide (Na2S) solution. Furthermore, an innovative compositive impregnation process was developed and then compared with the conventional direct impregnation process. Experimental results showed that the compositive impregnation process produced the sulfurized WPAC with high BET surface area and a high S content. A maximum BET surface area of 886 m2/g and the S content of 2.61% by mass were obtained at 900 degrees C and at the S feed ratio of 2160 mg Na2S/g C. However, the direct impregnation process led to a BET surface area of sulfurized WPAC that decreased significantly as the S content increased. PMID:15303299

Yuan, Chung-Shin; Lin, Hsun-Yu; Wu, Chun-Hsin; Liu, Ming-Han; Hung, Chung-Hsuang

2004-07-01

19

Towards advanced aqueous dye removal processes: a short review on the versatile role of activated carbon.  

PubMed

During the last decade, several physico-chemical and biological techniques have been developed to remove colour from textile wastewaters. Some of these techniques rely on and many will profit from activated carbon (AC). The role of AC is versatile: (1) it acts as a dye adsorbent, not only in straightforward adsorption processes but also in AC-enhanced coagulation and membrane filtration processes; (2) it generates strong oxidising agents (mostly, hydroxyl (OH) radicals) in electrochemical dye oxidation; (3) it catalyses OH production in advanced oxidation processes; (4) it catalyses anaerobic (azo) dye reduction and supports biofilm growth in microbial dye removal. This paper reviews the role of AC in dye decolourisation, evaluates the feasibility of each AC-amended decolourisation technique and discusses perspectives on future research. PMID:22459012

Mezohegyi, Gergo; van der Zee, Frank P; Font, Josep; Fortuny, Agustí; Fabregat, Azael

2012-03-28

20

Electrochemical properties of carbon-coated LiFePO 4 synthesized by a modified mechanical activation process  

Microsoft Academic Search

Carbon-coated lithium iron phosphate (LiFePO4\\/C) composites were synthesized by conventional mechanical activation (MA) process and also by a modified MA process. Phase-pure particles were obtained of ?100nm size with a nano-meter thick web of carbon surrounding the particles. The composite prepared by the modified MA process shows good performance as cathode material in lithium cells at room temperature. A high

Jae-Kwang Kim; Gouri Cheruvally; Jou-Hyeon Ahn; Gil-Chan Hwang; Jin-Beom Choi

2008-01-01

21

Steam-regenerated activated carbon: An emission-free, cost-effective ground water treatment process  

Microsoft Academic Search

Air stripping is frequently selected over carbon adsorption with virgin carbon for the removal of halogenated and aromatic solvents from contaminated ground water because it is the cheaper process when the volatilized organics can be emitted. However, increasing concern over the impact of the organics vented from an air stripping process has created a situation where ground water treatment costs

Charles S. Parmele; R. D. Allan; Mohsen Mehran

1986-01-01

22

Influences of pH, temperature and activated carbon properties on the interaction ozone\\/activated carbon for a wastewater treatment process  

Microsoft Academic Search

The influence of experimental parameters (T, pH) and activated carbon (AC) properties on the intensity and the nature (molecular or radical) of the ozone (O3) \\/AC interaction was studied to optimize an O3\\/AC wastewater treatment process. This interaction was investigated by studying the dissolved O3 decomposition kinetics in the presence of two commercial AC (Pica 150 and Picaflo), whose chemical

Hakim Dehouli; Olivier Chedeville; Benoît Cagnon; Vincent Caqueret; Catherine Porte

2010-01-01

23

The effect of processing conditions on microstructure of Pd-containing activated carbon fibers  

SciTech Connect

Palladium-doped activated carbon fibers are being evaluated as candidate materials for enhanced hydrogen storage at near ambient conditions. Pd-doped fibers were spun using a Pd salt mixed with an isotropic pitch precursor. Experimental techniques such as in-situ X-ray analysis, thermogravimetric studies, scanning transmission electron microscopy and gas adsorption were employed to understand how processing conditions for the production of Pd-doped activated carbon fibers affect the microstructure, pore development, and dispersion of metal particles throughout the fibers. The results showed that PdO phase is present in the stabilized fibers and that this oxide phase is stable up to about 250 aC. The oxide phase transforms into Pd metal with increasing heat treatment temperature, going through the formation of an intermediate carbide phase. Sintering of Pd particles was observed with heat treatment at temperatures over 750 aC. It was also found that pore development during physical activation with CO2 was not significantly affected by the presence of Pd particles within the fibers.

Wu, Xianxian [ORNL; Gallego, Nidia C [ORNL; Contescu, Cristian I [ORNL; Tekinalp, Halil [Clemson University; Bhat, Vinay V [ORNL; Baker, Frederick S [ORNL; Thies, Mark C [ORNL

2008-01-01

24

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

Microsoft Academic Search

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 (NH3-N), total dissolved salts

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

2011-01-01

25

GRANULAR ACTIVATED CARBONS FROM AGRICULTURAL BY-PRODUCTS: PROCESS DESCRIPTION AND ESTIMATED COST OF PRODUCTION  

Technology Transfer Automated Retrieval System (TEKTRAN)

A number of laboratories have described the use of pecan shells and sugarcane bagasse as feedstocks for activated carbon production. These carbons have found utility in a variety of applications, including metal ion remediation, sugar decolorization and adsorption of different organic pollutants. ...

26

Removal of diclofenac by conventional drinking water treatment processes and granular activated carbon filtration.  

PubMed

This study was carried out to evaluate the efficiency of conventional drinking water treatment processes with and without pre-oxidation with chlorine and chlorine dioxide and the use of granular activated carbon (GAC) filtration for the removal of diclofenac (DCF). Water treatment was performed using the Jar test with filters on a lab scale, employing nonchlorinated artesian well water prepared with aquatic humic substances to yield 20HU true color, kaolin turbidity of 70 NTU and 1mgL(-1) DCF. For the quantification of DCF in water samples, solid phase extraction and HPLC-DAD methods were developed and validated. There was no removal of DCF in coagulation with aluminum sulfate (3.47mgAlL(-1) and pH=6.5), flocculation, sedimentation and sand filtration. In the treatment with pre-oxidation and disinfection, DCF was partially removed, but the concentration of dissolved organic carbon (DOC) was unchanged and byproducts of DCF were observed. Chlorine dioxide was more effective than chorine in oxidizing DCF. In conclusion, the identification of DCF and DOC in finished water indicated the incomplete elimination of DCF through conventional treatments. Nevertheless, conventional drinking water treatment followed by GAC filtration was effective in removing DCF (?99.7%). In the oxidation with chlorine, three byproducts were tentatively identified, corresponding to a hydroxylation, aromatic substitution of one hydrogen by chlorine and a decarboxylation/hydroxylation. Oxidation with chlorine dioxide resulted in only one byproduct (hydroxylation). PMID:23540811

Rigobello, Eliane Sloboda; Dantas, Angela Di Bernardo; Di Bernardo, Luiz; Vieira, Eny Maria

2013-03-27

27

Treatment of coke-oven wastewater with the powdered activated carbon-contact stabilization activated sludge process. Final report  

SciTech Connect

The objective of the study was to determine optimum parameters for the operation of an innovative process train used in the treatment of coke-over wastewater. The treatment process train consisted of a contact-stabilization activated sludge system with powdered activated carbon (PAC) addition, followed by activated sludge nitrification, followed by denitrification in an anoxic filter. The control and operating parameters evaluated during the study were: (a) the average mixed-liquor PAC concentration maintained in the contact-stabilization system, (b) the solids retention time practiced in the contact-stabilization system, and (c) the hydraulic detention time maintained in the contact aeration tank. Three identical treatement process trains were constructed and employed in this study. The coke-oven wastewater used for this investigation was fed to the treatment units at 30% strength. The first part of the study was devoted to determining the interactions between the mixed liquor PAC concentration and the solids retention time in the contact-stabilization tanks. Results showed that optimum overall system performance is attainable when the highest sludge age (30 day) and highest mixed liquor PAC concentration were practiced. During the second phase of the study, all three systems were operated at a 30 day solids retention time while different detention times of 1, 2/3 and 1/3 day were evaluated in the contact tank. PAC addition rates were maintained at the former levels and, consequently, reduced contact times entailed higher mixed liquor carbon concentrations. Once again, the system receiving the highest PAC addition rate of PAC exhibited the best overall performance. This system exhibited no deterioration in process performance as a result of decreased contact detention time. 72 references, 41 figures, 24 tables.

Suidan, M.T.; Deady, M.A.; Gee, C.S.

1983-11-01

28

Powdered activated carbon and membrane bioreactors (MBRPAC) for tannery wastewater treatment: long term effect on biological and filtration process performances  

Microsoft Academic Search

This paper describes the findings of an experimental investigation carried out on a pilot scale membrane bioreactor (MBR) with the addition of powdered activated carbon (PAC) to analyze improvements in effluent quality and in the filtration process. The results refer to a pilot plant monitoring stretched over a period of 594 days: 380 without PAC, 123 with a PAC concentration

G. Munz; R. Gori; G. Mori; C. Lubello

2007-01-01

29

ACTIVATED CARBON FROM BROILER LITTER: PROCESS DESCRIPTION AND COST OF PRODUCTION  

Technology Transfer Automated Retrieval System (TEKTRAN)

Animal manure continues to represent a significantly large and problematic portion of the U.S. agricultural waste generated yearly. Granular activated carbons made from pelletized poultry litter have been shown to adsorb various positively charged metal ions from laboratory prepared solutions. Bas...

30

Thermal removal of mercury in spent powdered activated carbon from TOXECON process  

SciTech Connect

This research developed and demonstrated a technology to liberate Hg adsorbed onto powdered activated carbon (PAC) by the TOXECON process using pilot-scale high temperature air slide (HTAS) and bench-scale thermogravimetric analyzer (TGA). The HTAS removed 65, 83, and 92% of Hg captured with PAC when ran at 900{sup o}F, 1,000{sup o}F, and 1,200 {sup o}F, respectively, while the TGA removed 46 and 100% of Hg at 800 {sup o}F and 900{sup o}F, respectively. However, addition of CuO-Fe{sub 2}O{sub 3} mixture and CuCl catalysts enhanced Hg removal and PAC regeneration at lower temperatures. CuO-Fe{sub 2}O{sub 3} mixture performed better than CuCl in PAC regeneration. Scanning electron microscopy images and energy dispersive X-ray analysis show no change in PAC particle aggregation or chemical composition. Thermally treated sorbents had higher surface area and pore volume than the untreated samples indicating regeneration. The optimum temperature for PAC regeneration in the HTAS was 1,000{sup o}F. At this temperature, the regenerated sorbent had sufficient adsorption capacity similar to its virgin counterpart at 33.9% loss on ignition. Consequently, the regenerated PAC may be recycled back into the system by blending it with virgin PAC.

Okwadha, G.D.O.; Li, J.; Ramme, B.; Kollakowsky, D.; Michaud, D. [University of Wisconsin, Milwaukee, WI (United States)

2009-10-15

31

Study on Adsorption Process of Ethanol Vapor to Activated Carbon Fibers  

NASA Astrophysics Data System (ADS)

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

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

32

Production of activated carbons from Illinois coals  

SciTech Connect

Although the predominant use of coal is for combustion applications, more beneficial, reasonable and profitable uses may be as a resource for the production of chemicals, and materials, including activated carbon. Activated carbons represent a family of carbonaceous substances manufactured by processes that develop the carbon`s adsorptive properties. The primary objective of this study was to demonstrate that an activated carbon with good surface area and chemical properties could be produced from an Illinois coal.

Hippo, E.J.; O`Brien, W.S. [Southern Illinois Univ., Carbondale, IL (United States); Sun, Jian [Univ. of Illinois, Champaign, IL (United States)

1996-12-31

33

Activated carbon material  

DOEpatents

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.

Evans, A. Gary (North Augusta, SC)

1978-01-01

34

Synthesis of anatase titania-carbon nanotubes nanocomposites with enhanced photocatalytic activity through a nanocoating-hydrothermal process  

Microsoft Academic Search

Anatase TiO2 nanoparticles were covalently anchored onto acid-treated multi-walled carbon nanotubes (MWNTs) through a nanocoating-hydrothermal\\u000a process to obtain TiO2-MWNTs nanocomposites. The composition and structural properties of the nanocomposites were characterized by XRD, BET, TG,\\u000a TEM, HRTEM, EDX, XPS, and FTIR, and the formation of ester-bond linkage between TiO2 nanoparticles and MWNTs was demonstrated. The enhanced photocatalytic activity of TiO2-MWNTs nanocomposites

Qun Wang; Dong Yang; Daimei Chen; Yabo Wang; Zhongyi Jiang

2007-01-01

35

Carbon dioxide capture process with regenerable sorbents  

DOEpatents

A process to remove carbon dioxide from a gas stream using a cross-flow, or a moving-bed reactor. In the reactor the gas contacts an active material that is an alkali-metal compound, such as an alkali-metal carbonate, alkali-metal oxide, or alkali-metal hydroxide; or in the alternative, an alkaline-earth metal compound, such as an alkaline-earth metal carbonate, alkaline-earth metal oxide, or alkaline-earth metal hydroxide. The active material can be used by itself or supported on a substrate of carbon, alumina, silica, titania or aluminosilicate. When the active material is an alkali-metal compound, the carbon-dioxide reacts with the metal compound to generate bicarbonate. When the active material is an alkaline-earth metal, the carbon dioxide reacts with the metal compound to generate carbonate. Spent sorbent containing the bicarbonate or carbonate is moved to a second reactor where it is heated or treated with a reducing agent such as, natural gas, methane, carbon monoxide hydrogen, or a synthesis gas comprising of a combination of carbon monoxide and hydrogen. The heat or reducing agent releases carbon dioxide gas and regenerates the active material for use as the sorbent material in the first reactor. New sorbent may be added to the regenerated sorbent prior to subsequent passes in the carbon dioxide removal reactor.

Pennline, Henry W. (Bethel Park, PA); Hoffman, James S. (Library, PA)

2002-05-14

36

Hierarchically Porous Carbon Monoliths with High Surface Area from Bridged Poly(silsesquioxane) without Thermal Activation Process  

NASA Astrophysics Data System (ADS)

Hierarchically porous carbon monoliths with high specific surface areas have been fabricated by removing nano-sized silica phase from carbon/silica composites pyrolyzed from bridged poly(silsesquioxane). This activation method improves the homogeneity between inner and outer parts of the monoliths compared to the conventional thermal activation methods.

Hasegawa, G.; Kanamori, K.; Nakanishi, K.; Hanada, T.

2011-10-01

37

Activated carbon to the rescue  

SciTech Connect

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.

Sen, S. [Calgon Carbon Corp., Pittsburgh, PA (United States)

1996-03-01

38

Carbon dioxide absorption methanol process  

Microsoft Academic Search

A process is described for removing carbon dioxide from a feed stream of natural gas, having at least methane, ethane and heavier hydrocarbon, comprising: separating the feed stream in a first separator to form a first stream, having substantially all of the propane and heavier hydrocarbons and carbon dioxide and ethane, and a second stream, having methane, carbon dioxide and

Apffel

1987-01-01

39

Carbon dioxide absorption methanol process  

Microsoft Academic Search

This patent describes a process for removing carbon dioxide from a feed stream of natural gas having at least methane, ethane and heavier. It comprises: first, separating the feed stream in a first separator to form a first stream having substantially all of the propane and heavier hydrocarbons and carbon dioxide and ethane and a second stream, having methane, carbon

Apffel

1989-01-01

40

[Removal characters of ozone-biological activated carbon process for typical pollutants in southern brooky regions of China].  

PubMed

The products of relative molecular weight (Mr) distribution, bromate (BrO3(-)) and trihalomethanes (THMs) were studied by ozone-biological activated carbon (O3-BAC) process for treating organic matters and bromide (Br(-)) in water source of southern brooky regions of China. The experimental results showed that dissolved organic matters (DOC) with Mr lower than 10(3) accounted for 80% of the total. The removal rate of DOC and SUVA (UV254/DOC) were 8% and 14% respectively by traditional treatment process with main removalonly for ones with Mr higher than 100 x 10(3). Only 30% of DOC and 31% of SUVA were decreased by O3-BAC process for the removal of ones with Mr between 10(3) and 5 x 10(3), in which the biotic degradation was certainly restricted by predominant organic matters of hydrophilic and Mr was lower than 1000. An obvious increase of BrO3(-) occurred in the effluent from ozone oxidation process when the dose of ozone beyond 2 mg/L which increased Br(-) concentration. This could increase the product of BrO3(-). A poor and unstable removal effect of BrO3(-) was observed in the effluent of BAC process during the experiment. Each species of THMs, decreasing 40% of total, was reduced by O3-BAC treatment compared with the traditional treatment process. But the products of brominated trihalomethanes, especially CHBr3 would be markedly increased by enhanced chlorine dosage and Br(-) concentration. PMID:19558108

Lin, Tao; Chen, Wei; Wang, Lei-Lei

2009-05-15

41

Adsorption-desorption process using wood-based activated carbon for recovery of biosurfactant from fermented distillery wastewater.  

PubMed

Methods used for biosurfactant recovery include solvent extraction, precipitation, crystallization, centrifugation and foam fractionation. These methods cannot be used when distillery wastewater (DW) is used as the nutrient medium for biosurfactant production by Pseudomonas aeruginosa strain BS2, because recovery of biosurfactant by any of these methods imparts color to the biosurfactant. The biosurfactant has a nonaesthetic appearance with lowered surface active properties. These methods cannot be used for continuous recovery of biosurfactant during cultivation. Hence, a new downstream technique for biosurfactant recovery from fermented DW comprised of adsorption-desorption processes using wood-based activated carbon (WAC) was developed. This study involves batch experiments to standardize the factors affecting the rate of biosurfactant adsorption onto WAC. WAC was the most efficient adsorbent among various ones tested (i.e., silica gel, activated alumina and zeolite). The WAC (1% w v(-1)), equilibrium time (90 min), pH range of 5-10 and temperature of 40 degrees C were optimum to achieve 99.5% adsorption efficiency. Adsorption kinetics and intraparticle diffusion studies revealed the involvement of both boundary layer diffusion and intraparticle diffusion. The Langmuir adsorption isotherm of WAC indicated the formation of a monolayer coverage of the biosurfactant over a homogeneous carbon surface, while the Freundlich isotherm showed high adsorption at strong solute concentrations and low adsorption at dilute solute concentrations. WAC concentration of 4% w v(-1) facilitated complete removal of the biosurfactant from collapsed foam (contained 5-fold higher concentration of biosurfactant than was present in fermented DW). Biosurfactant adsorption was of chemisorption type. Acetone (polar solvent) was a specific viable eluant screened among various ones tested because it selectively facilitated maximum recovery, i.e., 89% biosurfactant from WAC. By acetone treatment, complete regeneration of WAC was feasible and WAC can be reused for biosurfactant recovery up to 3 cycles. The recovered biosurfactant showed improved surface-active property (i.e., much lower critical micelle concentration value of 0.013 verses 0.028 mg mL(-1) for biosurfactant recovered by classical methods). The reuse potential of WAC was assessed and results suggest that the carbon can be reused for three consecutive cycles for biosurfactant adsorption from fermented wastewater without any decrease in adsorption efficiency. Thus, this process forms a basis for continuous recovery of biosurfactant from fermented DW and concentrated foam. This process reduces the use of high cost solvent, avoids end product inhibition and minimizes product degradation. PMID:15932266

Dubey, Kirti V; Juwarkar, Asha A; Singh, S K

42

Ozone-biological activated carbon as a pretreatment process for reverse osmosis brine treatment and recovery  

Microsoft Academic Search

Ozonation was used in this study to improve biodegradability of RO brine from water reclamation facilities. An ozone dosage ranging from 3 to 10mg O3\\/L and contact times of 10 and 20min in batch studies were found to increase the biodegradability (BOD5\\/TOC ratio) of the RO brine by 1.8–3.5 times. At the same time, total organic carbon (TOC) removal was

Lai Yoke Lee; How Yong Ng; Say Leong Ong; Jiang Yong Hu; Guihe Tao; Kiran Kekre; Balakrishnan Viswanath; Winson Lay; Harry Seah

2009-01-01

43

Solvent-regenerated activated carbon  

SciTech Connect

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.

McLaughlin, H. (Fluids Design Corp., Troy, NY (USA))

1988-07-01

44

On the effect of process temperature on the performance of activated carbon bed hydrogen storage tank  

Microsoft Academic Search

A numerical model is used to investigate hydrogen charging in packed bed storage tank as function of the charging process temperature. The model is based on the solution of the 2D transport equations for mass, momentum and energy in porous media. The equation system is characterized by the existence of adsorption source terms in both mass and energy equations along

Gelareh Momen; Reza Jafari; Khaled Hassouni

2010-01-01

45

Catalysis effect of metal doping on wear properties of diamond-like carbon films deposited by a cathodic-arc activated deposition process  

Microsoft Academic Search

Diamond-like carbon (DLC) films containing various metal dopings were synthesized by using a cathodic-arc activated deposition process. Metal plasma with intensive ion energies catalyzes the decomposition of hydrocarbon gases (C2H2), and induces the formation of hydrogenated DLC films with a mixture of sp2 and sp3 carbon bonds. The composite film structure consists of a metal-doped DLC film on top of

Yin-Yu Chang; Da-Yung Wang; WeiTe Wu

2002-01-01

46

RO brine treatment and recovery by biological activated carbon and capacitive deionization process.  

PubMed

The generation of brine solutions from dense membrane (reverse osmosis, RO or nanofiltration, NF) water reclamation systems has been increasing worldwide, and the lack of cost effective disposal options is becoming a critical water resources management issue. In Singapore, NEWater is the product of a multiple barrier water reclamation process from secondary treated domestic effluent using MF/UF-RO and UV technologies. The RO brine (concentrates) accounts for more than 20% of the total flow treated. To increase the water recovery and treat the RO brine, a CDI based process with BAC as pretreatment was tested. The results show that ion concentrations in CDI product were low except SiO2 when compared with RO feed water. CDI product was passed through a RO and the RO permeate was of better quality including low SiO2 as compared to NEWater quality. It could be beneficial to use a dedicated RO operated at optimum conditions with better performance to recover the water. BAC was able to achieve 15-27% TOC removal of RO brine. CDI had been tested at a water recovery ranging from 71.6 to 92.3%. CDI based RO brine treatment could improve overall water recovery of NEWater production over 90%. It was found that calcium phosphate scaling and organic fouling was the major cause of CDI pressure increase. Ozone disinfection and sodium bisulfite dosing were able to reduce CDI fouling rate. For sustainable operation of CDI organic fouling control and effective organic fouling cleaning should be further studied. PMID:22053461

Tao, Guihe; Viswanath, Bala; Kekre, Kiran; Lee, Lai Yoke; Ng, How Yong; Ong, Say Leong; Seah, Harry

2011-01-01

47

Activated carbons prepared from phosphoric acid activation of grain sorghum  

Microsoft Academic Search

The production of activated carbons from grain sorghum with phosphoric acid activation has been studied by means of two processes, i.e., one-stage and two-stage. The former comprises simultaneous carbonization and activation after impregnation; the latter, the carbonization of the precursor at 300 °C for 15 min, followed by the activation of the resultant char after impregnation with phosphoric acid. The

Yulu Diao; W. P Walawender; L. T Fan

2002-01-01

48

Production of active carbons from waste tyres––a review  

Microsoft Academic Search

A review of the production of activated carbons from waste tyres is presented. The effects of various process parameters, particularly, temperature and heating rate, on the pyrolysis stage are reviewed. The influence of activating conditions, physical and chemical, nature of the activation chemicals, on the active carbon properties are discussed. Under certain process conditions several active carbons with BET surface

Edward L. K. Mui; Danny C. K. Ko; Gordon McKay

2004-01-01

49

Biochar as a precursor of activated carbon  

Microsoft Academic Search

Biochar was evaluated as a precursor of activated carbon. This product was produced by chemical activation using potassium\\u000a hydroxide. The effects of operating conditions of activation process, such as temperature, activating agent to biochar mass\\u000a ratio, and nitrogen flow rate, on the textural and chemical properties of the product were investigated. Activated carbon\\u000a produced by this method has internal surface

R. Azargohar; A. K. Dalai

2006-01-01

50

Photoconductivity of activated carbon fibers  

SciTech Connect

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.

Kuriyama, K.; Dresselhaus, M.S. (Massachusetts Inst. of Tech., Cambridge, MA (USA))

1990-08-01

51

Treatment of Reactive Black 5 by combined electrocoagulation-granular activated carbon adsorption-microwave regeneration process.  

PubMed

Treatment of an azo dye, Reactive Black 5 (RB5) by combined electrocoagulation-activated carbon adsorption-microwave regeneration process was evaluated. The toxicity was also monitored by the Vibrio fischeri light inhibition test. GAC of 100 g L(-1) sorbed 82% of RB5 (100 mg L(-1)) within 4h. RB5-loaded GAC was not effectively regenerated by microwave irradiation (800 W, 30s). Electrocoagulation showed high decolorization of RB5 within 8 min at pH(0) of 7, current density of 277 A m(-2), and NaCl of 1 g L(-1). However, 61% COD residue remained after treatment and toxicity was high (100% light inhibition). GAC of 20 g L(-1) effectively removed COD and toxicity of electrocoagulation-treated solution within 4h. Microwave irradiation effectively regenerated intermediate-loaded GAC within 30s at power of 800 W, GAC/water ratio of 20 g L(-1), and pH of 7.8. The adsorption capacity of GAC for COD removal from the electrocoagulation-treated solution did not significantly decrease at the first 7 cycles of adsorption/regeneration. The adsorption capacity of GAC for removal of both A(265) (benzene-related groups) and toxicity slightly decreased after the 6th cycle. PMID:19932556

Chang, Shih-Hsien; Wang, Kai-Sung; Liang, Hsiu-Hao; Chen, Hsueh-Yu; Li, Heng-Ching; Peng, Tzu-Huan; Su, Yu-Chun; Chang, Chih-Yuan

2009-10-30

52

Conceptual comparison of pink water treatment technologies: granular activated carbon, anaerobic fluidized bed, and zero-valent iron-Fenton process  

Microsoft Academic Search

Pink water, explosive-laden wastewater produced in army ammunition plants is often treated using expensive and non-destructive granular activated carbon (GAC) adsorption. This paper compares GAC adsorption and two alternative treatment technologies, anaerobic GAC fluidized bed reactor and zero- valent iron-Fenton process. The bench-scale demonstration of the zero-valent iron-Fenton process with real pink water is reported. The features of three technologies

S.-Y. Oh; D. K. Cha; P. C. Chiu; B. J. Kim

53

Inoculation of granular activated carbon in a fixed bed with S-triazine-degrading bacteria as a water treatment process  

Microsoft Academic Search

Two bacterial strains (SL1: Rhodococcus rhodochrous, WT1: Acinetobacter junii) capable of biodegrading atrazine and simazine in surface water (1–10 ?g l?1) were inoculated into fixed beds of granular activated carbon (GAC, 20 min empty bed contact time, EBCT). Eluted SL1, WT1 and indigenous bacteria were enumerated by spread plate on nutrient agar. Bacteria attached to GAC were desorbed in 50

Stephanie J. Feakin; E. Blackburn; R. G. Burns

1995-01-01

54

Equilibrium uptake, sorption dynamics, process optimization, and column operations for the removal and recovery of malachite green from wastewater using activated carbon and activated slag  

SciTech Connect

The waste slurry generated in fertilizer plants and slag (blast furnace waste) have been converted into low-cost adsorbents, activated carbon and activated slag, respectively, and these are utilized for the removal of malachite green (a basic dye) from wastewater. In the batch experiments, parameters studied include the effect of pH, sorbent dosage, adsorbate concentration, temperature, and contact time. Kinetic studies have been performed to have an idea of the mechanistic aspects and to obtain the thermodynamic parameters of the process. The uptake of the dye is greater on carbonaceous material than on activated slag. Sorption data have been correlated with both Langmuir and Freundlich adsorption models. The presence of anionic surfactants does not affect the uptake of dye significantly. The mass transfer kinetic approach has been applied for the determination of various parameters necessary for the designing of fixed-bed contactors. Chemical regeneration has been achieved with acetone in order to recover the loaded dye and restore the column to its original capacity without dismantling the same.

Gupta, V.K.; Srivastava, S.K.; Mohan, D. [Univ. of Roorkee (India). Chemistry Dept.

1997-06-01

55

Activated carbon from municipal waste  

Microsoft Academic Search

A refuse derived fuel (RDF) was carbonized by partial combustion at 623 K and the carbonized RDF (cRDF) was steam-activated at 1123 K. The cRDF was also treated by 3.3 or 5.2 N nitric acid at a boiling temperature for 3 h prior to the steam-activation. Porous properties of the activated carbons prepared were determined by the nitrogen adsorption method.

S Nagano; H Tamon; T Adzumi; K Nakagawa; T Suzuki

2000-01-01

56

Persulfate regeneration of trichloroethylene spent activated carbon.  

PubMed

The objective of this study was to demonstrate the regeneration of trichloroethylene (TCE) spent activated carbon using persulfate oxidation and iron activated persulfate (IAP) oxidation. Both processes resulted in decreases in the adsorbability of regenerated activated carbons. IAP was shown to rapidly degrade the aqueous TCE and causes a significant mineralization of the TCE. The release of chloride ions provided evidence of this. Persulfate oxidation mainly resulted in desorption of TCE from the activated carbon and only partial mineralization of the TCE through a carbon activated persulfate reaction mechanism. Concerning destruction of the TCE, in the regeneration test using persulfate, 30% of the original TCE was present in the solution and 9% remained on the activated carbon after the first regeneration cycle. In contrast, in the test that used IAP, it was observed that no TCE was present in the solution and only approximately 5% of the original TCE remained on the activated carbon after the first regeneration. Following the regeneration cycles, elemental analysis was carried out on the samples. BET surface area and EDS analysis showed some effects on the physico-chemical properties of the activated carbon such as a slight decrease in the surface area and the presence of iron precipitates on the carbon. PMID:19264399

Liang, Chenju; Lin, Ya-Ting; Shin, Wu-Hang

2009-02-12

57

Biomorphic activated porous carbons with complex microstructures from lignocellulosic residues  

Microsoft Academic Search

Transformation of coir fibers, coir pith and coconut shell endocarp microstructures is described for the formation of activated carbons. The carbonization\\/activation process was carried out using ZnCl2 as activating agent at 800°C under CO2 atmosphere. The carbonization\\/activation process was evaluated by TGA\\/DTG measurements which evidenced an increase in the initial decomposition temperature along with increase in the carbon amount as

Jeremias S. Macedo; Larissa Otubo; Odair Pastor Ferreira; Iara de Fátima Gimenez; Italo Odone Mazali; Ledjane Silva Barreto

2008-01-01

58

Effects of high salinity and constituent organic compounds on treatment of photo-processing waste by a sulfur-oxidizing bacteria\\/granular activated carbon sludge system  

Microsoft Academic Search

To achieve practical treatment of photo-processing waste (PW) using our previously proposed sulfur-oxidizing bacteria (SOB)\\/granular activated carbon (GAC) sludge system, this paper elucidates why 3- to 5-X dilution of PW was required. That is, a series of experiments were carried out to show the effects of high salinity and constituent organic compounds in PW, respectively. Both an inorganic salts system

Bin-Le Lin; Masaaki Hosomi; Akihiko Murakami

2002-01-01

59

Recover VOCs via adsorption on activated carbon  

SciTech Connect

One of the most effective methods of controlling emissions of volatile organic compounds (VOCs) is also one of the most economical--adsorption, usually using activated carbon as the adsorbent. This process is cost-effective because it is typically able to recover many VOCs for reuse. A particularly common application of carbon adsorption for VOC control is solvent recovery. In general, solvent recovery via carbon adsorption is a logical consideration for any industrial process exhausting sizable quantities of valuable solvent (subject, of course, to the solvent's suitability for adsorption by activated carbon, as discussed later). The most commonly recovered solvents include toluene; heptane; hexane; carbon tetrachloride; acetone; ethyl acetate; methyl ethyl ketone(MEK); naphthalene; and methylene chloride. Many other solvents are also suitable for recovery by carbon adsorption. A recent CEP article discussed the basics of carbon adsorption and application of the technology to water and wastewater treatment. This article takes an in-depth look at the use of activated carbon adsorption of the control of airborne VOC emissions and solvent recovery. It outlines how to decide if carbon adsorption is suitable for an application and then explains how to implement the technology.

Ruhl, M.J. (Dedert Corp., Olympia Falls, IL (United States). Solvent Recovery Div.)

1993-07-01

60

Carbon Sequestration Monitoring Activities  

Microsoft Academic Search

In its 'Carbon Sequestration Technology Roadmap and Program Plan 2007' the U.S. Department of Energy (DOE)'s Office of Fossil Energy National Energy Technology Laboratory (NETL) identified as a major objective extended field tests to fully characterize potential carbon dioxide (CO) storage sites and to demonstrate the long-term storage of sequestered carbon (p. 5). Among the challenges in this area are

Carol Frost

2010-01-01

61

Carbon Isotope Ratios in Belowground Carbon Cycle Processes  

Microsoft Academic Search

Abstract Analyses of carbon isotope ratios (?,C values of CO2effluxing from soils, but asof,yet a global,database,is lacking,with which,to test this prediction. Such a global,database,would be a useful input for global carbon cycle models,which,rely on ?values,to constrain source and sink relations. Keywords: global change, ecosystem processes, soil organic carbon, carbon isotope ratio, carbon cycle,

James R. Ehleringer; Nina Buchmann; Lawrence B. Flanagan

2000-01-01

62

High Surface Area Activated Carbon from Waste Biomass  

Microsoft Academic Search

The present work relates to efforts made towards developing a high surface area, activated carbon from rubber wood sawdust by a two-stage activation process with phosphoric acid as the activating agent. Experiments are conducted in lab scale using muffle furnace under static conditions in a self-generated atmosphere covering process parameters such as impregnation ratio, carbonization time and temperature. The process

C. Srinivasakannan

63

Catalytic activation of carbon monoxide  

Microsoft Academic Search

Research into the catalytic activation of carbon monoxide has direct applications to the industrial use of synthesis gas as a feedstock for manufacturing synfuels and other organic chemicals. Synthesis gas is comprised of hydrogen\\/carbon monoxide mixtures produced from coal and other carbonaceous materials. Its potential uses include production of oxygenated organic material such as methanol and ethylene glycol, conversion to

Ford

1981-01-01

64

Interactions of xanthines with activated carbon  

NASA Astrophysics Data System (ADS)

Because of their pharmaceutical and industrial applications, we have studied the adsorption of xanthine derivates (caffeine and theophylline) by activated carbon. To this end, we examined kinetic, equilibrium and thermodynamic aspects of the process. This paper reports the kinetics results. The experimental results indicate that the process was first order in C and the overall process was assumed to involve a single, reversible adsorption desorption process obeying a kinetic law postulated by us.

Navarrete Casas, R.; García Rodriguez, A.; Rey Bueno, F.; Espínola Lara, A.; Valenzuela Calahorro, C.; Navarrete Guijosa, A.

2006-06-01

65

Nanospace engineering of KOH activated carbon  

NASA Astrophysics Data System (ADS)

This paper demonstrates that nanospace engineering of KOH activated carbon is possible by controlling the degree of carbon consumption and metallic potassium intercalation into the carbon lattice during the activation process. High specific surface areas, porosities, sub-nanometer (<1 nm) and supra-nanometer (1-5 nm) pore volumes are quantitatively controlled by a combination of KOH concentration and activation temperature. The process typically leads to a bimodal pore size distribution, with a large, approximately constant number of sub-nanometer pores and a variable number of supra-nanometer pores. We show how to control the number of supra-nanometer pores in a manner not achieved previously by chemical activation. The chemical mechanism underlying this control is studied by following the evolution of elemental composition, specific surface area, porosity, and pore size distribution during KOH activation and preceding H3PO4 activation. The oxygen, nitrogen, and hydrogen contents decrease during successive activation steps, creating a nanoporous carbon network with a porosity and surface area controllable for various applications, including gas storage. The formation of tunable sub-nanometer and supra-nanometer pores is validated by sub-critical nitrogen adsorption. Surface functional groups of KOH activated carbon are studied by microscopic infrared spectroscopy.

Romanos, J.; Beckner, M.; Rash, T.; Firlej, L.; Kuchta, B.; Yu, P.; Suppes, G.; Wexler, C.; Pfeifer, P.

2012-01-01

66

THERMAL REGENERATION OF ACTIVATED CARBON  

EPA Science Inventory

Ecologically, petrochemical wastes constitute a major hazard since waste materials contain relatively large amounts of non-biodegradable and toxic materials which may be discharged continuously. A three-part experimental study of activated carbon adsorption and thermal regenerati...

67

Carbon Sequestration Monitoring Activities  

SciTech Connect

In its 'Carbon Sequestration Technology Roadmap and Program Plan 2007' the U.S. Department of Energy (DOE)'s Office of Fossil Energy National Energy Technology Laboratory (NETL) identified as a major objective extended field tests to fully characterize potential carbon dioxide (CO{sub 2}) storage sites and to demonstrate the long-term storage of sequestered carbon (p. 5). Among the challenges in this area are 'improved understanding of CO{sub 2} flow and trapping within the reservoir and the development and deployment of technologies such as simulation models and monitoring systems' (p. 20). The University of Wyoming (UW), following consultations with the NETL, the Wyoming State Geological Survey, and the Governor's office, identified potential for geologic sequestration of impure carbon dioxide (CO{sub 2}) in deep reservoirs of the Moxa Arch. The Moxa Arch is a 120-mile long north-south trending anticline plunging beneath the Wyoming Thrust Belt on the north and bounded on the south by the Uinta Mountains. Several oil and gas fields along the Moxa Arch contain accumulations of natural CO{sub 2}. The largest of these is the La Barge Platform, which encompasses approximately 800 square miles. Several formations may be suitable for storage of impure CO{sub 2} gas, foremost among them the Madison Limestone, Bighorn Dolomite, and Nugget Sandstone. This project responded to the challenges described above by preparing a geological site characterization study on the Moxa Arch. The project included four priority research areas: (A) geological characterization of geologic structure of the Arch, the fault, and fracture patterns of the target formations and caprocks, (B) experimental characterization of carbon dioxide-brine-rock reactions that may occur, (C) optimization of geophysical and numerical models necessary for measurement, monitoring and verification (MMV), and (D) a preliminary performance assessment. Research work to accomplish these goals was coordinated by one administrative task under the direction of Dr. Carol Frost, Professor of Geology and Geophysics (Task 1.0), and one task devoted to designing and creating an interdisciplinary, project-specific carbon cyberinfrastructure to support collaborative carbon dioxide sequestration research among University of Wyoming scientists and their collaborators, performed by Jeff Hammerlinck, Director of the Wyoming Geographic Information Science Center at the University of Wyoming (Task 1.5). The results of these tasks are presented in the Introduction and in Chapter 1, respectively.

Carol Frost

2010-11-30

68

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

PubMed

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%). PMID:23485237

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

2013-01-01

69

WASTE ACTIVATED SLUDGE PROCESSING  

EPA Science Inventory

A study was made at pilot scale of a variety of processes for dewatering and stabilization of waste activated sludge from a pure oxygen activated sludge system. Processes evaluated included gravity thickening, dissolved air flotation thickening, basket centrifugation, scroll cent...

70

Gold recovery by microwave augmented ashing of waste activated carbon  

Microsoft Academic Search

Gold ore processing plants that utilize carbon adsorption technologies generate a waste activated carbon, which contains very high gold values, and the recovery of this gold represents a significant source of extra revenue. In this research, microwave energy was utilized to combust the waste activated carbon and the resulting ash was treated by conventional cyanide leaching to recover the gold.

R. K. Amankwah; C. A. Pickles; W.-T. Yen

2005-01-01

71

Plasma Processing for Carbon Nanomaterials  

NASA Astrophysics Data System (ADS)

Plasma is a useful tool to synthesize carbon nano-materials including diamond, fullerene, nanotube and graphene. This review introduces the overview of these carbon nano-materials produced by thermal or non-thermal plasmas and also the authors' work related to plasma-enhanced chemical vapor deposition of carbon nanotubes and its correlation with numerical simulation of CH4/H2 feedstock gas plasmas. The amount of carbon atoms in the CNTs grown and that calculated from simulation showed good agreement.

Suda, Yoshiyuki; Takikawa, Hirofumi; Tanoue, Hideto

72

Aqueous carbonate process design study. Final report  

Microsoft Academic Search

The Aqueous Carbonate Process (ACP) Design Study involved an experimental investigation of the regeneration subsystem of the Rockwell International Corporation Energy Systems Group closed cycle flue gas desulfurization process. The process involves a spray dryer in which the flue gas is scrubbed and its sulfur removed as a dry sodium sulfite\\/sulfate plus sodium carbonate mixture. This is followed by a

R. L. McKisson; G. L. Bauerle; J. E. Bodine; R. D. Rennick; A. E. Stewart; S. Tsang

1980-01-01

73

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...

74

Effects of free cyanide on microbial communities and biological carbon and nitrogen removal performance in the industrial activated sludge process.  

PubMed

The changes in process performance and microbial communities under free cyanide (CN(-)) were investigated in a lab-scale activated sludge process treating industrial wastewater. The performance of phenol degradation did not appear to be adversely affected by increases in CN(-) concentrations. In contrast, CN(-) was found to have an inhibitory effect on SCN(-) biodegradation, resulting in the increase of TOC and COD concentrations. Nitratation also appeared to be inhibited at CN(-) concentrations in excess of 1.0 mg/L, confirming that nitrite-oxidizing bacteria (NOB) is more sensitive to the CN(-) toxicity than ammonia oxidizing bacteria (AOB). After CN(-) loads were stopped, SCN(-) removal, denitrification, and nitrification inhibited by CN(-) were recovered to performance efficiency of more than 98%. The AOB and NOB communities in the aerobic reactor were analyzed by terminal restriction fragment length (T-RFLP) and quantitative real-time PCR (qPCR). Nitrosomonas europaea lineage was the predominant AOB at all samples during the operation, but an obvious change was observed in the diversity of AOB at the shock loading of 30 and 50 mg/L CN(-), resulting in Nitrosospira sp. becoming dominant. We also observed coexisting Nitrospira and Nitrobacter genera for NOB. The increase of CN(-) loading seemed to change the balance between Nitrospira and Nitrobacter, resulting in the high dominance of Nitrobacter over Nitrospira. Meanwhile, through using the qPCR, it was observed that the nitrite-reducing functional genes (i.e., nirS) were dominant in the activated sludge of the anoxic reactor, regardless of CN(-) loads. PMID:21047665

Kim, Young Mo; Lee, Dae Sung; Park, Chul; Park, Donghee; Park, Jong Moon

2010-10-19

75

NaCl adsorption in multi-walled carbon nanotube\\/active carbon combination electrode  

Microsoft Academic Search

In this paper, we proposed a new process for fabricating electrochemical double layer capacitors employing active carbon and multi-walled carbon nanotubes to adsorb Na+ and Cl- from NaCl solution. Due to their unique mesoporosity, active carbons have high ability to desalt NaCl solution. But they have many defects such as high electrical resistance, high-energy consumption and low intensity. Since carbon

Kai Dai; Liyi Shi; Dengsong Zhang; Jianhui Fang

2006-01-01

76

Combustion processes for carbon capture  

Microsoft Academic Search

A review of the technologies for coal-based power generation closest to commercial application involving carbon capture is presented. Carbon capture and storage (CCS) developments are primarily adaptations of conventional combustion systems, with additional unit operations such as bulk oxygen supply, CO2 capture by sorbents, CO2 compression, and storage. They use pulverized coal combustion in entrained flow—the dominant current technology for

Terry F. Wall

2007-01-01

77

Water adsorption with hysteresis effect onto microporous activated carbon fabrics  

Microsoft Academic Search

Understanding the adsorption of water vapor onto activated carbons is important for designing processes to remove dilute contaminants\\u000a from humid gas streams, such as providing protection against chemical warfare agents (CWAs), or against toxic industrial compounds\\u000a (TICs) used in a terrorist chemical attack. Water vapor isotherms for Calgon BPL granular activated carbon (GAC), military\\u000a ASZM-TEDA GAC, electrospun activated carbon nanofibers

Patrick D. Sullivan; Brenton R. Stone; Zaher Hashisho; Mark J. Rood

2007-01-01

78

Effects of high salinity and constituent organic compounds on treatment of photo-processing waste by a sulfur-oxidizing bacteria/granular activated carbon sludge system.  

PubMed

To achieve practical treatment of photo-processing waste (PW) using our previously proposed sulfur-oxidizing bacteria (SOB)/granular activated carbon (GAC) sludge system, this paper elucidates why 3- to 5-X dilution of PW was required. That is, a series of experiments were carried out to show the effects of high salinity and constituent organic compounds in PW, respectively. Both an inorganic salts system and calcination PW system showed that SOB completely oxidizes S2O(3)2- -S to SO(4)2- -S even at 12.3 or 13.6% salinity, respectively; hence the dilution requirement is not attributable to high salinity. In experiments employing SOB and SOB/GAC systems to investigate the effects of 23 constituent compounds in PW, compounds were classified into Groups I, II, IIIa, and IIIb. Even with 10 g/l GAC, the nine compounds in Group IIIb still exhibited a toxic effect on SOB activity at 1- and 3-X dilutions; thus it is these compounds that are responsible for requiring dilution of PW. Accordingly, a reduction in their use within the photodeveloping and fix-stabilizing industry, and/or use of > 10g/l GAC, are new considerations for establishing a more practical PW treatment process. PMID:11848345

Lin, Bin-Le; Hosomi, Masaaki; Murakami, Akihiko

2002-02-01

79

Engineering carbon materials from the hydrothermal carbonization process of biomass.  

PubMed

Energy shortage, environmental crisis, and developing customer demands have driven people to find facile, low-cost, environmentally friendly, and nontoxic routes to produce novel functional materials that can be commercialized in the near future. Amongst various techniques, the hydrothermal carbonization (HTC) process of biomass (either of isolated carbohydrates or crude plants) is a promising candidate for the synthesis of novel carbon-based materials with a wide variety of potential applications. In this Review, we will discuss various synthetic routes towards such novel carbon-based materials or composites via the HTC process of biomass. Furthermore, factors that influence the carbonization process will be analyzed and the special chemical/physical properties of the final products will be discussed. Despite the lack of a clear mechanism, these novel carbonaceous materials have already shown promising applications in many fields such as carbon fixation, water purification, fuel cell catalysis, energy storage, CO(2) sequestration, bioimaging, drug delivery, and gas sensors. Some of the most promising examples will also be discussed here, demonstrating that the HTC process can rationally design a rich family of carbonaceous and hybrid functional carbon materials with important applications in a sustainable fashion. PMID:20217791

Hu, Bo; Wang, Kan; Wu, Liheng; Yu, Shu-Hong; Antonietti, Markus; Titirici, Maria-Magdalena

2010-02-16

80

Active carbon catalyst for heavy oil upgrading  

Microsoft Academic Search

The active carbon (AC) catalyst was studied by hydrocracking of Middle Eastern vacuum residue (VR) for heavy oil upgrading. It was observed that the active carbon has the affinity to heavy hydrocarbon compounds and adsorption selectivity to asphaltenes, and exhibits better ability to restrict the coke formation during the hydrocracking reaction of VR. The mesopore of active carbon was thought

Hidetsugu Fukuyama; Satoshi Terai; Masayuki Uchida; José L. Cano; Jorge Ancheyta

2004-01-01

81

Kinetics of Diuron Adsorption onto Activated Carbon Fiber  

Microsoft Academic Search

A study was conducted on the adsorption kinetics of diuron from aqueous solutions onto activated carbon fiber. The results showed that the formation of hydrogen bonds between diuron and water, and temperature variations may possibly affect the adsorption process. Furthermore, adsorption of diuron onto activated carbon fiber was affected remarkably by solution pH and the maximum adsorption amount was achieved

Jianhua Xu; Yabing Sun; Zhenyu Li; Jingwei Feng

2011-01-01

82

Studies and characterisations of various activated carbons used for carbon\\/carbon supercapacitors  

Microsoft Academic Search

Various activated carbons from the PICA Company have been tested in supercapacitor cells in order to compare their performances. The differences measured in terms of specific capacitance and cell resistance are presented. Porosity measurements made on activated carbon powders and electrode allowed a better understanding of the electrochemical behaviour of these activated carbons. In this way, the PICACTIF SC carbon

J Gamby; P. L Taberna; P Simon; J. F Fauvarque; M Chesneau

2001-01-01

83

H2O2-based oxidation processes for the regeneration of activated carbons saturated with volatile organic compounds of different polarity.  

PubMed

This study reports the sequential regeneration treatment of activated carbons (ACs) saturated with volatile organic compounds (VOCs) of different polarity using H(2)O(2) as oxidizing agent. In this process, VOCs were adsorbed onto the AC and further oxidized by H(2)O(2). A commercial AC was selected and saturated with three different VOCs: two non-polar and hydrophobic VOCs, toluene and limonene, and one polar and hydrophilic VOC, methyl ethyl ketone (MEK). The saturated AC was regenerated with H(2)O(2), and the Fenton reagent for comparison. It was found that regeneration efficiencies obtained with the H(2)O(2) treatment were equal to or even higher than those obtained with the Fenton treatment. The fate of the pre-adsorbed VOCs, once the regeneration process is completed was studied. It was found that this regeneration treatment is limited for non-polar VOCs such as toluene and limonene, as they tend to remain adsorbed onto the ACs after regeneration treatment. Contrarily, MEK tend to be transferred to the bulk phase and react with the generated oxidant species. PMID:23273734

Anfruns, Alba; Montes-Morán, Miguel A; Gonzalez-Olmos, Rafael; Martin, María J

2012-12-25

84

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

PubMed

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

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

2013-05-07

85

Process for making carbon foam  

SciTech Connect

The process obviates the need for conventional oxidative stabilization. The process employs mesophase or isotropic pitch and a simplified process using a single mold. The foam has a relatively uniform distribution of pore sizes and a highly aligned graphic structure in the struts. The foam material can be made into a composite which is useful in high temperature sandwich panels for both thermal and structural applications.

Klett, J.W.

2000-03-07

86

A Novel Approach to Mineral Carbonation: Enhancing Carbonation While Avoiding Mineral Pretreatment Process Cost  

SciTech Connect

Known fossil fuel reserves, especially coal, can support global energy demands for centuries to come, if the environmental problems associated with CO{sub 2} emissions can be overcome. Unlike other CO{sub 2} sequestration candidate technologies that propose long-term storage, mineral sequestration provides permanent disposal by forming geologically stable mineral carbonates. Carbonation of the widely occurring mineral olivine (e.g., forsterite, Mg{sub 2}SiO{sub 4}) is a large-scale sequestration process candidate for regional implementation, which converts CO{sub 2} into the environmentally benign mineral magnesite (MgCO{sub 3}). The primary goal is cost-competitive process development. As the process is exothermic, it inherently offers low-cost potential. Enhancing carbonation reactivity is key to economic viability. Recent studies at the U.S. DOE Albany Research Center have established that aqueous-solution carbonation using supercritical CO{sub 2} is a promising process; even without olivine activation, 30-50% carbonation has been achieved in an hour. Mechanical activation (e.g., attrition) has accelerated the carbonation process to an industrial timescale (i.e., near completion in less than an hour), at reduced pressure and temperature. However, the activation cost is too high to be economical and lower cost pretreatment options are needed. We have discovered that robust silica-rich passivating layers form on the olivine surface during carbonation. As carbonation proceeds, these passivating layers thicken, fracture and eventually exfoliate, exposing fresh olivine surfaces during rapidly-stirred/circulating carbonation. We are exploring the mechanisms that govern carbonation reactivity and the impact that (1) modeling/controlling the slurry fluid-flow conditions, (2) varying the aqueous ion species/size and concentration (e.g., Li+, Na+, K+, Rb+, Cl-, HCO{sub 3}{sup -}), and (3) incorporating select sonication offer to enhance exfoliation and carbonation. Thus far, we have succeeded in nearly doubling the extent of carbonation observed compared with the optimum procedure previously developed by the Albany Research Center. Aqueous carbonation reactivity was found to be a strong function of the ionic species present and their aqueous activities, as well as the slurry fluid flow conditions incorporated. High concentration sodium, potassium, and sodium/potassium bicarbonate aqueous solutions have been found to be the most effective solutions for enhancing aqueous olivine carbonation to date. Slurry-flow modeling using Fluent indicates that the slurry-flow dynamics are a strong function of particle size and mass, suggesting that controlling these parameters may offer substantial potential to enhance carbonation. During the first project year we developed a new sonication exfoliation apparatus with a novel sealing system to carry out the sonication studies. We also initiated investigations to explore the potential that sonication may offer to enhance carbonation reactivity. During the second project year, we extended our investigations of the effects of sonication on the extent of carbonation as a function of the following parameters: particle size distribution, the mass of solid reactant, volume fraction of aqueous solution present, sonication power, time, temperature, and CO{sub 2} pressure. To date, none of the conditions investigated have significantly enhanced carbonation. Mechanistic investigations of the stirred ({approx}1,500 rpm) aqueous olivine carbonation process indicate the carbonation process involves both incongruent magnesium dissolution and silica precipitation, which results in robust silica-rich passivating layer formation. Secondary ion mass spectrometry observation of H within the passivating layer that forms during static carbonation suggests 2H{sup +}/Mg{sup 2+} ion exchange is associated with incongruent dissolution. Apparently, H{sub 2}O forms at or near the olivine/passivating-layer interface during the process and diffuses out through the passivating layers during the carbonation reaction. This is

Andrew V. G. Chizmeshya; Michael J. McKelvy; Kyle Squires; Ray W. Carpenter; Hamdallah Bearat

2007-06-21

87

Preparation of activated carbon from bituminous coal with phosphoric acid activation  

Microsoft Academic Search

Activated carbons were prepared from an Australian bituminous coal in this study. The preparation process consisted of phosphoric acid impregnation followed by carbonization in nitrogen at 400–600°C for 1–3hours. The results reveal that the surface area and pore volume of the resulting carbons increase with the chemical ratio, H3PO4\\/coal. Within the ranges of carbonization temperature and time, the chemically activated

Hsisheng Teng; Tien-Sheng Yeh; Li-Yeh Hsu

1998-01-01

88

Regeneration of granular activated carbon saturated with acetone and isopropyl alcohol via a recirculation process under H 2O 2\\/UV oxidation  

Microsoft Academic Search

This study examines a water-based system, coupling an adsorber and a photoreactor, for regeneration of granular activated carbon (GAC) saturated with acetone and isopropyl alcohol (IPA). Through water recirculation the regeneration reaction was operated in both intermittent and continuous ultraviolet illumination modes. With a periodic dosage of hydrogen peroxide not only was regeneration efficient but it was also catalyzed by

Richard S. Horng; I.-Chin Tseng

2008-01-01

89

Role of carbon substrates in facilitating energy reduction and resource recovery in a traditional activated sludge process: investigation from a biokinetics modeling perspective.  

PubMed

Three activated sludge processes (ASPs) were modeled and driven by dissolved complex organics (F-ASP), propionic acid (P-ASP), and acetic acid (A-ASP), and various parameters were subsequently estimated. The energy depletion for carbon removal was 0.146, 0.120, and 0.119 kWh/m(3) of treated wastewater for F-ASP, P-ASP, and A-ASP, respectively, suggesting that acetic acid can forward energy conservation. The ratio of substrate storage to oxidation in F-ASP, P-ASP, and A-ASP was 0, 0.25, and 0.52, respectively, further demonstrating that substrate eliminations from P-ASP and A-ASP were both dominated by substrate storage for polymer production, not by total oxidation; thus, they exhibited lower energy-consuming levels than F-ASP. Quantification of bioenergy production and nutrient acquisition from the excess sludge of the three ASPs were conducted subsequently, and A-ASP was found to facilitate phosphorus capture. PMID:23711939

Wang, Xu; Liu, Junxin; Qu, Bo; Ren, Nan-Qi; Qu, Jiuhui

2013-05-06

90

Purification process for vertically aligned carbon nanofibers.  

PubMed

Individual, free-standing, vertically aligned multiwall carbon nanotubes or nanofibers are ideal for sensor and electrode applications. Our plasma-enhanced chemical vapor deposition techniques for producing free-standing and vertically aligned carbon nanofibers use catalyst particles at the tip of the fiber. Here we present a simple purification process for the removal of iron catalyst particles at the tip of vertically aligned carbon nanofibers derived by plasma-enhanced chemical vapor deposition. The first step involves thermal oxidation in air, at temperatures of 200-400 degrees C, resulting in the physical swelling of the iron particles from the formation of iron oxide. Subsequently, the complete removal of the iron oxide particles is achieved with diluted acid (12% HCl). The purification process appears to be very efficient at removing all of the iron catalyst particles. Electron microscopy images and Raman spectroscopy data indicate that the purification process does not damage the graphitic structure of the nanotubes. PMID:12908239

Nguyen, Cattien V; Delziet, Lance; Matthews, Kristopher; Chen, Bin; Meyyappan, M

91

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

Microsoft Academic Search

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,

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

2006-01-01

92

Modeling carbonizing process in fluidized bed  

NASA Astrophysics Data System (ADS)

This paper presents possibility of using neural networks model for designing carbonizing process in fluidized bed. This process is very complicated and difficult as multi-parameters changes are non linear and car drive cross structure is non homogeneous. This fact and lack of mathematical algorithms describing this process makes modeling properties of drives elements by traditional numerical methods difficult or even impossible. In this case it is possible to try using artificial neural network. Using neural networks for modeling carbonizing in fluidized bed is caused by several nets' features: non linear character, ability to generalize the results of calculations for data out of training set, no need for mathematical algorithms describing influence changes input parameters on modeling materials properties. The neural network structure is designed and special prepared by choosing input and output parameters of process. The method of learning and testing neural network, the way of limiting nets structure and minimizing learning and testing error are discussed. Such prepared neural network model, after putting expected values of car cross driving properties in output layer, can give answers to a lot of questions about running carbonizing process in fluidized bed. The practical implications of the neural network models are possibility of using they to build control system capable of on-line controlling running process and supporting engineering decision in real time. The originality of this research is different conception to obtain foreseen materials properties after carbonizing in fluidized bed. The specially prepared neural networks model could be a help for engineering decisions and may be used in designing carbonizing process in fluidized bed as well as in controlling changes of this process.

Szota, M.; Jasinski, J.

2010-06-01

93

ALKALINE CARBONATE LEACHING PROCESS FOR URANIUM EXTRACTION  

DOEpatents

A process for the leaching of uranium from high carbonate ores is presented. According to the process, the ore is leached at a temperature of about 200 deg C and a pressure of about 200 p.s.i.g. with a solution containing alkali carbonate, alkali permanganate, and bicarbonate ion, the bicarbonate ion functionlng to prevent premature formation of alkali hydroxide and consequent precipitation of a diuranate. After the leaching is complete, the uranium present is recovered by precipitation with NaOH.

Thunaes, A.; Brown, E.A.; Rabbitts, A.T.

1957-11-12

94

Cellulosic carbon fibers with branching carbon nanotubes for enhanced electrochemical activities for bioprocessing applications.  

PubMed

Renewable biobased carbon fibers are promising materials for large-scale electrochemical applications including chemical processing, energy storage, and biofuel cells. Their performance is, however, often limited by low activity. Herein we report that branching carbon nanotubes can enhance the activity of carbonized cellulosic fibers, such that the oxidation potential of NAD(H) was reduced to 0.55 V from 0.9 V when applied for bioprocessing. Coordinating with enzyme catalysts, such hierarchical carbon materials effectively facilitated the biotransformation of glycerol, with the total turnover number of NAD(H) over 3500 within 5 h of reaction. PMID:24020801

Zhao, Xueyan; Lu, Xin; Tze, William Tai Yin; Kim, Jungbae; Wang, Ping

2013-09-13

95

SORPTION OF ELEMENTAL MERCURY BY ACTIVATED CARBONS  

EPA Science Inventory

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

96

Mechanisms of Activated Carbon Degradation by Perspiration.  

National Technical Information Service (NTIS)

Amino acids harm the adsorption capacity of a carbon more than lactic or formic acid. Water can plug up carbon micropores. This water can be removed in a drying oven. In tests, the more harmful chemicals to adsorption capacity of an activated carbon were ...

L. L. Pytlewski

1976-01-01

97

Evaluation of Activated Carbon for Fuel Oil Adsorption from a Potable Water Supply.  

National Technical Information Service (NTIS)

Evaluation of activated carbon adsorption process to remove diesel fuel from a contaminated Air Force Water supply was accomplished. Laboratory scale tests proved activated carbon highly capable of removing diesel fuel from water. Determinations of adsorp...

D. H. Allen

1976-01-01

98

Study of Multielemental Adsorption on Activated Carbon  

NASA Astrophysics Data System (ADS)

In this study, multielemental adsorption on activated carbon (AC) was investigated. The treatment parameters (pH, AC concentration, metal concentration and contact time) in the adsorption process of multiple metals such as Bi, Cd, Co, Ga, Mn, Mo, Ni, In, Pb, Pd, Sn, Rh, Ru and W were experimented. Three types of characteristic behaviors of analyte elements were observed when the pH was varied. The adsorption rate of Bi, Co, Ga, Ni, In, Pb, Sn, Ru and W were over 80% within 30 min.

Thuy, Le Thi Xuan; Yasuzawa, Mikito; Yabutani, Tomoki

99

Comparison between activated carbon, carbon xerogel and carbon nanotubes for the adsorption of the antibiotic ciprofloxacin  

Microsoft Academic Search

A comparison was made for the adsorption capacity of ciprofloxacin (CPX) on three types of carbon-based materials: activated carbon, carbon nanotubes and carbon xerogel. The obtained samples were characterised by adsorption of N2 at ?196°C, determination of the point of zero charge and by temperature programmed desorption. The Langmuir and Freundlich models were used to describe the equilibrium isotherms obtained.

S. A. C. Carabineiro; T. Thavorn-amornsri; M. F. R. Pereira; P. Serp; J. L. Figueiredo

100

Process for flash carbonization of biomass  

US Patent & Trademark Office Database

A low-energy input process for the pyrolytic conversion of biomass to charcoal or carbonized charcoal is provided. The biomass is sealed in a container, pressurized with air and heated to ignition. Control of pressure by input of air and release of gases to maintain successively lower pressure levels results in a typical time for the conversion of less than 30 minutes.

2004-09-14

101

Preparation of activated carbon microspheres from phenolic-resin by supercritical water activation  

Microsoft Academic Search

Supercritical water (SCW) has been employed as an efficient activating agent for the preparation of activated carbon microspheres (P-ACS) with developed mesopores from phenolic-resin. Several processing factors that influenced the activation reaction, including activation temperature, activation duration, supercritical pressure and water flow rate were investigated. Increasing activation temperature and duration lead to larger porosity and higher specific surface area as

Qiong Cai; Zheng-Hong Huang; Feiyu Kang; Jun-Bing Yang

2004-01-01

102

Thermocatalytic process for CO.sub.2-free production of hydrogen and carbon from hydrocarbons  

SciTech Connect

A novel process and apparatus are disclosed for sustainable CO.sub.2-free production of hydrogen and carbon by thermocatalytic decomposition (dissociation, pyrolysis, cracking) of hydrocarbon fuels over carbon-based catalysts in the absence of air and/or water. The apparatus and thermocatalytic process improve the activity and stability of carbon catalysts during the thermocatalytic process and produce both high purity hydrogen (at least, 99.0 volume %) and carbon, from any hydrocarbon fuel, including sulfurous fuels. In a preferred embodiment, production of hydrogen and carbon is achieved by both internal and external activation of carbon catalysts. Internal activation of carbon catalyst is accomplished by recycling of hydrogen-depleted gas containing unsaturated and aromatic hydrocarbons back to the reactor. External activation of the catalyst can be achieved via surface gasification with hot combustion gases during catalyst heating. The process and apparatus can be conveniently integrated with any type of fuel cell to generate electricity.

Muradov, Nazim Z. (Melbourne, FL)

2011-08-23

103

Preparation of activated carbons from macadamia nut shell and coconut shell by air activation  

Microsoft Academic Search

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

Man S. Tam; Michael Jerry Antal

1999-01-01

104

Thermodynamic characterization of a regenerated activated carbon surface  

NASA Astrophysics Data System (ADS)

Calorimetric measurements of the immersion enthalpy in different liquids of a set of regenerated activated carbons have been employed to analyze the effect of a regeneration process on the extension of the accessible surface area and the hydrophobic character of the carbons by comparison with the original carbon. The modifications in the hydrophobicity of the activated carbons are quantified by the analysis of the surface free energy of the solids and its dispersion and non-dispersion components. It has been found that regeneration treatment of the original carbon increases its accessible surface area and hydrophobicity. However, the opposite effects take place when regeneration is done on the same carbon previously saturated with p-nitrophenol (PNP) or p-chlorophenol (PClP).

González-Mart?´n, M. L.; González-Garc?´a, C. M.; González, J. F.; Ramiro, A.; Sabio, E.; Bruque, J. M.; Encinar, J. M.

2002-05-01

105

A Novel Approach To Mineral Carbonation: Enhancing Carbonation While Avoiding Mineral Pretreatment Process Cost  

SciTech Connect

Known fossil fuel reserves, especially coal, can support global energy demands for centuries to come, if the environmental problems associated with CO{sub 2} emissions can be overcome. Unlike other CO{sub 2} sequestration candidate technologies that propose long-term storage, mineral sequestration provides permanent disposal by forming geologically stable mineral carbonates. Carbonation of the widely occurring mineral olivine (e.g., forsterite, Mg{sub 2}SiO{sub 4}) is a large-scale sequestration process candidate for regional implementation, which converts CO{sub 2} into the environmentally benign mineral magnesite (MgCO{sub 3}). The primary goal is cost-competitive process development. As the process is exothermic, it inherently offers low-cost potential. Enhancing carbonation reactivity is key to economic viability. Recent studies at the U.S. DOE Albany Research Center have established that aqueous-solution carbonation using supercritical CO{sub 2} is a promising process; even without olivine activation, 30-50% carbonation has been achieved in an hour. Mechanical activation (e.g., attrition) has accelerated the carbonation process to an industrial timescale (i.e., near completion in less than an hour), at reduced pressure and temperature. However, the activation cost is too high to be economical and lower cost pretreatment options are needed. Herein, we report our second year progress in exploring a novel approach that offers the potential to substantially enhance carbonation reactivity while bypassing pretreatment activation. As our second year progress is intimately related to our earlier work, the report is presented in that context to provide better overall understanding of the progress made. We have discovered that robust silica-rich passivating layers form on the olivine surface during carbonation. As carbonation proceeds, these passivating layers thicken, fracture and eventually exfoliate, exposing fresh olivine surfaces during rapidly-stirred/circulating carbonation. We are exploring the mechanisms that govern carbonation reactivity and the impact that (i) modeling/controlling the slurry fluid-flow conditions, (ii) varying the aqueous ion species/size and concentration (e.g., Li{sup +}, Na{sup +}, K{sup +}, Rb{sup +}, Cl{sup -}, HCO{sub 3}{sup -}), and (iii) incorporating select sonication offer to enhance exfoliation and carbonation. We have succeeded in nearly doubling the extent of carbonation observed compared with the optimum procedure previously developed by the Albany Research Center. Aqueous carbonation reactivity was found to be a strong function of the ionic species present and their aqueous activities, as well as the slurry fluid flow conditions incorporated. High concentration sodium, potassium, and sodium/potassium bicarbonate aqueous solutions have been found to be the most effective solutions for enhancing aqueous olivine carbonation to date. Slurry-flow modeling using Fluent indicates that the slurry-flow dynamics are a strong function of particle size and mass, suggesting that controlling these parameters may offer substantial potential to enhance carbonation. Synergistic control of the slurry-flow and aqueous chemistry parameters offers further potential to improve carbonation reactivity, which is being investigated during the no-cost extension period. During the first project year we developed a new sonication exfoliation system with a novel sealing system to carry out the sonication studies. We also initiated(Abstract truncated).

Michael J. McKelvy; Andrew V. G. Chizmeshya; Kyle Squires; Ray W. Carpenter; Hamdallah Bearat

2006-06-21

106

s-Process in Shell Carbon Burning  

NASA Astrophysics Data System (ADS)

We present a study of carbon-shell s-process nucleosynthesis in a 25 Msun model having solar-like initial composition as a follow-up of our previous s-process study of core helium burning. The source of free neutrons, as in the core helium burning, is the 22Ne(? ,n)25Mg reaction with the initial 22Ne is what left from the core helium burning. We show the temperature, density, neutron density, and 12C, 22Ne, 80Kr, 86Sr, 87Rb mass fractions evolution during the carbon-shell burning. The model produces a neutron exposure of ~1 mbarn-1 and a peak neutron density of ~1x1011 cm-3 at the inner edge of carbon shell (mass radius ~2 Msun) with the duration of s-process of ~1 year. We find all isotopes except 64Zn with proton number between 30 and 40 have an overproduction factor larger than unity in the carbon-shell s-process. These overlay the core helium overproduction factors. The isotopes that are strongly produced are 180Ta, 23Na, 70,72,73,74Ge, 80,82,83Kr, 69,71Ga, 76,77,78,80Se, 66,67,68Zn, 64Ni, 75,79Br, 87Rb, 79,81Br. The isotopes that are strongly destroyed during carbon-shell burning are 58Fe, 64Zn, 63,65Cu, 152Gd, 158Dy, 37Cl, 113In. This work is supported by NSF grant AST-9819877.

The, L.-S.; Meyer, B. S.; El Eid, M. F.

2001-12-01

107

The regeneration of field-spent granular-activated carbons.  

PubMed

The thermal regeneration of field-spent granular-activated carbons (GAC) is being increasingly adopted as a cost-effective alternative to disposal. The success of this practice requires the adjustment of process conditions to maximise the recovery of the original carbon characteristics while minimising carbon loss. This paper describes an investigation into the regeneration of several field-spent GAC representative of those typically generated by the drinking water treatment industry. The carbons were initially investigated for their ash contents and inorganic compositions in order to determine the accumulation of metallic species that affect the regeneration process. Regeneration was conducted in steam at 800 degrees C over reaction times between 0 and 60 min in order to achieve different degrees of carbon gasification. Weight losses were determined for each condition and the resulting carbons characterised for their apparent density, porosity, surface area and aqueous adsorption characteristics. Results showed that spent carbons recovered most of their adsorption characteristics when heated to 800 degrees C under inert conditions. Steam gasification in the range of 5-10 wt% burn-off had some positive effects on the characteristics of the spent carbons which were in most cases counteracted by a reduction in the carbon yield. Steam gasification in excess of 15 wt% burn-off caused a rapid increase in the carbon mesoporosity but a significant deterioration in the carbon microporosity, BET surface area and adsorption capacity for organic species of small molecular size. PMID:11456174

Miguel, G S; Lambert, S D; Graham, N J

2001-08-01

108

Activated carbon for gas phase arsenic capture  

Microsoft Academic Search

Investigation of activated carbon as a multifunctional sorbent for trace metal capture is the focus of this study. In addition to mercury and halides, selenium and arsenic represent two of the most volatile trace species that remain in gas phase in substantial amounts. In this work, fundamental sorption characteristics of the activated carbon for arsenic removal from the gas phase

R. Jadhav; H. Gupta; S. Misro; R. Agnihotri; L. S. Fan

1999-01-01

109

ACTIVATED CARBON FROM LIGNITE FOR WATER TREATMENT  

Microsoft Academic Search

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

Edwin S. Olson; Daniel J. Stepan

2000-01-01

110

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

111

Catalytic Growth of Macroscopic Carbon Nanofibers Bodies with Activated Carbon  

SciTech Connect

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.

Abdullah, N.; Muhammad, I. S.; Hamid, S. B. Abd. [NANOCEN, Block A, Level 3, Institute of Postgraduate Studies, University of Malaya, 50603 Kuala Lumpur (Malaysia); Rinaldi, A. [NANOCEN, Block A, Level 3, Institute of Postgraduate Studies, University of Malaya, 50603 Kuala Lumpur (Malaysia); Inorganic Chemistry Department, Fritz-Haber Institute der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin (Germany); Su, D. S.; Schlogl, R. [Inorganic Chemistry Department, Fritz-Haber Institute der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin (Germany)

2009-06-01

112

Antibacterial pitch-based activated carbon fiber supporting silver  

Microsoft Academic Search

Pitch-based activated carbon fiber (ACF) supporting silver (ACF(Ag)) was prepared by pre-oxidization, carbonization, activation, immersion and decomposition processes. The structures, surface photographs and functional groups of the ACF and the ACF(Ag) were investigated. The ACF exhibited increased oxygen-containing functional groups and decreased BET specific surface areas after supporting silver particles. The ACF(Ag) with C?OH, C?O, -COOH and -COOAg groups showed

Ch. Y. Li; Y. Z. Wan; J. Wang; Y. L. Wang; X. Q. Jiang; L. M. Han

1998-01-01

113

Dynamic pesticide removal with activated carbon fibers.  

PubMed

Rapid small-scale minicolumn tests were carried out to simulate the atrazine adsorption in water phase with three pelletized pitch-based activated carbon fibers (ACF) and one commercial granular activated carbon (GAC). Initial atrazine solutions were prepared with pretreated ground water. Minicolumn tests showed that the performance of highly activated carbon fibers (surface area of 1700 m2/g) is around 7 times better than the commercial GAC (with surface area at around 1100 m2/g), whereas carbon fibers with medium activation degree (surface area of 1500 m2/g) had a removal efficiency worse than the commercial carbon. The high removal efficiency of the highly activated ACF is due to the wide-opened microstructure of the material, with an appreciable contribution of the low size mesopores, maintaining at these conditions a fast kinetic adsorption rate rather than a selective adsorbent for micropollutants vs. natural organic matter. PMID:11229006

Martín-Gullón, I; Font, R

2001-02-01

114

Sorption of boron trifluoride by activated carbons  

SciTech Connect

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.

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

1988-01-10

115

Cyclic process for converting methane to carbon disulfide  

SciTech Connect

This patent describes a cyclic process for converting methane to carbon disulfide. It comprises: decomposing methane on a solid carrier in a decomposition zone under conditions sufficient to generate hydrogen and to deposit elemental carbon on the solid carrier; transporting the carbon-containing solid carrier from the decomposition zone to a carbon/sulfur reaction zone; contacting the carbon-containing solid carrier with sulfur in the carbon/sulfur reaction zone under conditions sufficient to convert the elemental carbon and sulfur to carbon disulfide, thereby removing elemental carbon from the carrier; and transporting the carrier from the carbon/sulfur reaction zone to sid decomposition zone and repeating previous steps.

Audeh, C.A.; Bell, W.K.

1990-10-16

116

Carbon formation and metal dusting in advanced coal gasification processes  

SciTech Connect

The product gases generated by coal gasification systems contain high concentrations of CO and, characteristically, have relatively high carbon activities. Accordingly, carbon deposition and metal dusting can potentially degrade the operation of such gasifier systems. Therefore, the product gas compositions of eight representative gasifier systems were examined with respect to the carbon activity of the gases at temperatures ranging from 480 to 1,090 C. Phase stability calculations indicated that Fe{sub 3}C is stable only under very limited thermodynamic conditions and with certain kinetic assumptions and that FeO and Fe{sub 0.877}S tend to form instead of the carbide. As formation of Fe{sub 3}C is a necessary step in the metal dusting of steels, there are numerous gasifier environments where this type of carbon-related degradation will not occur, particularly under conditions associated with higher oxygen and sulfur activities. These calculations also indicated that the removal of H{sub 2}S by a hot-gas cleanup system may have less effect on the formation of Fe{sub 3}C in air-blown gasifier environments, where the iron oxide phase can exist and is unaffected by the removal of sulfur, than in oxygen-blown systems, where iron sulfide provides the only potential barrier to Fe{sub 3}C formation. Use of carbon- and/or low-alloy steels dictates that the process gas composition be such that Fe{sub 3}C cannot form if the potential for metal dusting is to be eliminated. Alternatively, process modifications could include the reintroduction of hydrogen sulfide, cooling the gas to perhaps as low as 400 C and/or steam injection. If higher-alloy steels are used, a hydrogen sulfide-free gas may be processed without concern about carbon deposition and metal dusting.

DeVan, J.H.; Tortorelli, P.F.; Judkins, R.R.; Wright, I.G.

1997-02-01

117

Removal of Cr(VI) from aqueous solution using activated carbon modified with nitric acid  

Microsoft Academic Search

The adsorption processes of Cr(VI) from aqueous solution onto a granular activated carbon (GAC) and a modified activated carbon (MAC) with nitric acid have been investigated. The surface characteristics of these two activated carbons were measured. The results showed that the MAC has a lower surface area, lower pHIEP and more oxygen functional groups compared with the GAC. Adsorption parameters

Guolin Huang; Jeffrey X. Shi; Tim A. G. Langrish

2009-01-01

118

The Use of Activated Carbon Prepared from Jackfruit (Artocarpus heterophyllus) Peel Waste for Methylene Blue Removal  

Microsoft Academic Search

Jackfruit peel waste which has no economic value has been utilized for activated carbon preparation. The preparation of the activated carbon was carried out using chemical activation with phosphoric acid as activating agent. The impregnation ratio was 4:1 (g H3PO4\\/g raw material) and semi carbonization process was conducted at 200oC and followed with carbonization at 550oC. The applicability of this

Devarly PRAHAS; Yoga KARTIKA; Nani INDRASWATI; Suryadi ISMADJI

119

Pastures to forests: a regional assessment of soil carbon sequestration, and carbon cycling processes  

NASA Astrophysics Data System (ADS)

Afforestation of agricultural land is increasingly recognized as a viable means of mitigating against climate change. However, the effects of afforestation on soil carbon stocks, and the time scales over which they change, remain unclear. Here we present results of a detailed investigation of how soil carbon stocks and cycling change following afforestation of pastures. 1. We conducted a global meta-analysis of published data on the effects of afforestation of pastures on soil carbon and nitrogen stocks in a Mediterranean climate. Results indicate that more than 30 years will be needed for soil carbon stocks to reach those of remnant forests. 2. We surveyed soil carbon and nitrogen at 40 sites across southeastern Australia, spanning a chronosequence (5-45 years old) of existing plantings, and their adjacent pastures to account for differences in soil type and land-use history among sites. Whereas changes in total soil carbon were not yet evident, a shift in the C:N ratio of the soils, and an increase in the density of plant litter, was observed. 3. We undertook a detailed analysis of soil carbon stocks at a sub-set of our field sites to determine the optimum number of soil samples needed to provide an accurate estimate of soil carbon in mixed species plantings. 4. We studied carbon and nutrient cycling in afforested pastures to gain new process level knowledge. Together the results presented here will be discussed in the context of the role of revegetation activities to sequester carbon in the soil on the regional scale.

Cavagnano, Timothy; Cunningham, Shaun; Hoogmoed, Marianne

2013-04-01

120

Environmental Study of an Activated Carbon Plant.  

National Technical Information Service (NTIS)

This report is a summary of the environmental aspects arising from the production of activated carbon. The methods for pollution control are specified and the emissions and predicted ambient concentrations given. Recommendations are made to achieve satisf...

P. Clayton S. C. Wallin

1978-01-01

121

Transport properties of activated carbon fibers.  

National Technical Information Service (NTIS)

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 therm...

S. L. di Vittorio M. S. Dresselhaus M. Endo J. P. Issi L. Piraux

1990-01-01

122

Carbon dioxide adsorption in chemically activated carbon from sewage sludge.  

PubMed

In this work, sewage sludge was used as precursor in the production of activated carbon by means of chemical activation with KOH and NaOH. The sludge-based activated carbons were investigated for their gaseous adsorption characteristics using CO2 as adsorbate. Although both chemicals were effective in the development of the adsorption capacity, the best results were obtained with solid NaOH (SBA(T16)). Adsorption results were modeled according to the Langmuir and Freundlich models, with resulting CO2 adsorption capacities about 56 mg/g. The SBA(T16) was characterized for its surface and pore characteristics using continuous volumetric nitrogen gas adsorption and mercury porosimetry. The results informed about the mesoporous character of the SBA(T16) (average pore diameter of 56.5 angstroms). The Brunauer-Emmett-Teller (BET) surface area of the SBA(T16) was low (179 m2/g) in comparison with a commercial activated carbon (Airpel 10; 1020 m2/g) and was mainly composed of mesopores and macropores. On the other hand, the SBA(T16) adsorption capacity was higher than that of Airpel 10, which can be explained by the formation of basic surface sites in the SBA(T16) where CO2 experienced chemisorption. According to these results, it can be concluded that the use of sewage-sludge-based activated carbons is a promising option for the capture of CO2. Implications: Adsorption methods are one of the current ways to reduce CO2 emissions. Taking this into account, sewage-sludge-based activated carbons were produced to study their CO2 adsorption capacity. Specifically, chemical activation with KOH and NaOH of previously pyrolyzed sewage sludge was carried out. The results obtained show that even with a low BET surface area, the adsorption capacity of these materials was comparable to that of a commercial activated carbon. As a consequence, the use of sewage-sludge-based activated carbons is a promising option for the capture of CO2 and an interesting application for this waste. PMID:23786147

de Andrés, Juan Manuel; Orjales, Luis; Narros, Adolfo; de la Fuente, María del Mar; Encarnación Rodríguez, María

2013-05-01

123

USE OF ACTIVATED CARBON FOR SOIL BIOREMEDIATION  

Microsoft Academic Search

The use of activated carbon may help overcome the toxicity of organic pollutants to microbes and plants during soil bioremediation.\\u000a Experiments were conducted with 3,4-dichloroaniline (DCA), 2,4,6-trinitrotoluene (TNT), and polychlorinated biphenyls (PCB)\\u000a to demonstrate that activated carbon (AC) can reduce the toxicity of readily available chemicals in soil by transferring them\\u000a to a less toxic soil fraction.

Galina K. Vasilyeva; Elena R. Strijakova; Patrick J. Shea

124

Catalytic decomposition of methane over activated carbon  

Microsoft Academic Search

Methane decomposition over activated carbons was carried out in a fixed bed, quartz-tube flow reactor. The kinetics of methane decomposition and surface properties changes before and after reaction was investigated. As a non-carbon based material, active alumina was also used to compare and understand the catalytic decomposition mechanism of methane over different materials. A reaction order of 0.5 is obtained

Zongqing Bai; Haokan Chen; Baoqing Li; Wen Li

2005-01-01

125

Fixation of potassium aurocyanide on active carbons  

Microsoft Academic Search

Active carbons of different origins (ex-coconut shell, ex-coal, ex-peat and ex-wood) have been used as adsorbents of potassium aurocyanide. Various treatments were applied to the active carbons: heat treatment at 800 °C, heat treatment at 800 °C followed by HCl (11) washing, heat treatment at 650 °C, washing with HCl 10%, esterification with methanol, oxidation with nitric acid and extraction

Eugène Papirer; Anundo Polania-Leon; Jean-Baptiste Donnet; Philippe Montagnon

1995-01-01

126

Adsorption of herbicides using activated carbons  

SciTech Connect

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

Derbyshire, F.; Jagtoyen, M.; Lafferty, C.; Kimber, G. [Univ. of Kentucky, Lexington, KY (United States)

1996-12-31

127

Numerical modeling of the carbonization process in the manufacture of carbon\\/carbon composites  

Microsoft Academic Search

A method for the numerical simulation of the carbonization process is introduced. A general model for the transient analyses of heat and mass transfer together with stress and displacement predictions is constructed using two-dimensional FEM (finite element method) for arbitrary geometry. The established model is applied to the carbonization of a single-phase, homogeneous, isotropic phenolic foam, and an anisotropic, two-phase

Jungin Kim; Woo Il Lee; Khalid Lafdi

2003-01-01

128

Impact of Process and Energy Efficiency in Mineral Processing on Abatement of Carbon Emissions  

Microsoft Academic Search

Mineral processing industry is facing tough challenges regarding abatement of carbon emissions, the use of water and energy. Mine activities requires bulk material handling, mineral ore transportation with haul trucks and machinery with important use of diesel fuel that produce direct emissions while plant operations have an intensive use of electrical energy with important indirect emissions. Based on available secondary

Jorge Pontt; Juan Yianatos; Luis Bergh; Waldo Valderrama; Fernando Rojas; Manuel Olivares; Hernán Robles; Manuel López

2010-01-01

129

Characterization of carbon nanofiber composites synthesized by shaping process  

Microsoft Academic Search

Catalytically grown carbon nanofibers (CNFs) are shaped into pellets in desired size and configuration by a conventional molding process so as to extend the potential applications of CNFs in industrial heterogeneous catalysis. After shaping, a novel carbon nanofiber composite with sufficient mechanical strength is produced, in which isolated CNFs are connected by a carbon network formed through polymer binder carbonization.

Ping Li; Tie-Jun Zhao; Jing-Hong Zhou; Zhi-Jun Sui; Ying-Chun Dai; Wei-Kang Yuan

2005-01-01

130

Activated carbon for gas phase arsenic capture  

SciTech Connect

Investigation of activated carbon as a multifunctional sorbent for trace metal capture is the focus of this study. In addition to mercury and halides, selenium and arsenic represent two of the most volatile trace species that remain in gas phase in substantial amounts. In this work, fundamental sorption characteristics of the activated carbon for arsenic removal from the gas phase are investigated. Activated carbons with different structural properties are studied for their usefulness in removing arsenic species from flue gas. Arsenic oxide (As{sub 2}O{sub 3}) is used as the source of arsenic. Preliminary sorption studies indicate that arsenic removal occurs by physical adsorption, with increased capture by carbons with higher surface areas.

Jadhav, R.; Gupta, H.; Misro, S.; Agnihotri, R.; Fan, L.S.

1999-07-01

131

Tertiary activated carbon treatment of paper and board industry wastewater.  

PubMed

The feasibility of activated carbon post-treatment of (biologically treated) wastewater from the paper and board industry was investigated, the goal being to remove refractory organic pollutants and produce water that can be re-used in the production process. Because closing water-circuits in the paper and board industry results in higher water temperatures, the effect of the temperature on activated carbon treatment was also investigated. Batch and column adsorption tests showed that activated carbon provides an excellent removal of cationic demand and color related compounds, the two most important representatives of organic compounds that have to be removed. Unexpectedly, higher water temperatures enhanced the performance of activated carbon. However, the treatment costs, mainly determined by transport and regeneration of the carbon, were very high. At long contact times between the wastewater and the carbon the occurrence of biodegradation was observed. Biological regeneration of the carbon may therefore provide a means to reduce the treatment costs, but a practical application requires further research. PMID:15935653

Temmink, Hardy; Grolle, Katja

2005-10-01

132

A novel carbon-based process for flue gas cleanup  

SciTech Connect

The objective of this project is to demonstrate the preliminary technical and economic feasibility of a novel carbon-based process for removal of at least 95 % SO[sub 2], and at least 75 % NO[sub x] from coal combustion flue gas. In the process, flue gas leaving the electrostatic precipitator (ESP) is passed through a trickle bed of activated carbon catalyst employing a periodic flush of low strength sulfuric acid. The SO[sub 2] is oxidized to SO[sub 3] and removed as medium strength sulfuric acid. The SO[sub 2]-free flue gas is then mixed with NH[sub 3], and the NO[sub x] in the gas is subjected to selective catalytic reduction (SCR) to N[sub 2] over a fixed bed of activated carbon catalyst. In the previous six quarters, detailed project plans were prepared and experimental systems were commissioned. The SO[sub 2] removal factorial experiments with BPL carbon at 21[degrees]C are well underway at Waterloo. A modified carbon catalyst (MCCI) showed up to 99% SO[sub 2] removal in the presence of NO[sub x] over 10 multiple cycles at 80--130[degrees]C and 1400 scc/cc/h. Several catalysts were evaluated for NO[sub x] removal also. Promising modified carbon catalysts (MCCI, II and III) were tested. Some of these catalysts showed the potentialfor over 80% NO[sub x] removal at space velocities as high as 3000 scc/cc/h. Poisoning of NO[sub x] removal efficiency with SO[sub 2] in the feed was also studied. With over 100 ppm SO[sub 2] in feed, NO[sub x]removal efficiency remained steady for several hours. It declined from 79% removal to 66% removal over 24 hours. NO[sub x] removal experiments were performed with 5 different materials and the SO[sub 2] removalactivity of 2 catalysts was tested.

Gangwal, S.K. (Research Triangle Inst., Research Triangle Park, NC (United States)); Silveston, P.L. (Waterloo Univ., ON (Canada))

1993-04-01

133

Microwave-assisted regeneration of activated carbon.  

PubMed

Microwave heating was used in the regeneration of methylene blue-loaded activated carbons produced from fibers (PFAC), empty fruit bunches (EFBAC) and shell (PSAC) of oil palm. The dye-loaded carbons were treated in a modified conventional microwave oven operated at 2450 MHz and irradiation time of 2, 3 and 5 min. The virgin properties of the origin and regenerated activated carbons were characterized by pore structural analysis and nitrogen adsorption isotherm. The surface chemistry was examined by zeta potential measurement and determination of surface acidity/basicity, while the adsorptive property was quantified using methylene blue (MB). Microwave irradiation preserved the pore structure, original active sites and adsorption capacity of the regenerated activated carbons. The carbon yield and the monolayer adsorption capacities for MB were maintained at 68.35-82.84% and 154.65-195.22 mg/g, even after five adsorption-regeneration cycles. The findings revealed the potential of microwave heating for regeneration of spent activated carbons. PMID:22728787

Foo, K Y; Hameed, B H

2012-05-22

134

Removal of diethyl phthalate from water solution by adsorption, photo-oxidation, ozonation and advanced oxidation process (UV/H?O?, O?/H?O? and O?/activated carbon).  

PubMed

The objective of this work was to compare the effectiveness of conventional technologies (adsorption on activated carbon, AC, and ozonation) and technologies based on advanced oxidation processes, AOPs, (UV/H(2)O(2), O(3)/AC, O(3)/H(2)O(2)) to remove phthalates from aqueous solution (ultrapure water, surface water and wastewater). Diethyl phthalate (DEP) was chosen as a model pollutant because of its high water solubility (1,080 mg/L at 293 K) and toxicity. The activated carbons showed a high adsorption capacity to adsorb DEP in aqueous solution (up to 858 mg/g), besides the adsorption mechanism of DEP on activated carbon is governed by dispersive interactions between ? electrons of its aromatic ring with ? electrons of the carbon graphene planes. The photodegration process showed that the pH solution does not significantly affect the degradation kinetics of DEP and the first-order kinetic model satisfactorily fitted the experimental data. It was observed that the rate of decomposition of DEP with the O(3)/H(2)O(2) and O(3)/AC systems is faster than that with only O(3). The technologies based on AOPs (UV/H(2)O(2), O(3)/H(2)O(2), O(3)/AC) significantly improve the degradation of DEP compared to conventional technologies (O(3), UV). AC adsorption, UV/H(2)O(2), O(3)/H(2)O(2), and O(3)/AC showed a high yield to remove DEP; however, the disadvantage of AC adsorption is its much longer time to reach maximum removal. The best system to treat water (ultrapure and natural) polluted with DEP is the O(3)/AC one since it achieved the highest DEP degradation and TOC removal, as well as the lower water toxicity. PMID:23178761

Medellin-Castillo, Nahum A; Ocampo-Pérez, Raúl; Leyva-Ramos, Roberto; Sanchez-Polo, Manuel; Rivera-Utrilla, José; Méndez-Díaz, José D

2012-11-21

135

Carbon-carbon bond activation in cyclopropane by energetic forms of hydrogen on the Ni(100) surface  

Microsoft Academic Search

Carbon-carbon bond activation is important in catalytic processes, and is observed here at a low temperature during reactions of adsorbed cyclopropane with both gas phase atomic hydrogen and bulk hydrogen in the presence of surface hydrogen on the Ni(100) surface. The large energies possessed by gas phase atomic hydrogen may allow substantial activation barriers to be overcome in the absence

Kyung-Ah Son; John L. Gland

1995-01-01

136

Surface studies of novel hydrophobic active carbons  

NASA Astrophysics Data System (ADS)

The efficient adsorption of toxic organic species from humid airstreams by active carbons is impeded by the competitive adsorption of water vapour which, at low values of p/ ps, occurs at specific (polar) adsorption sites located at the edges of the carbon layer-planes and at in-plane defects. At higher pressures, adsorption in micropores and mesopores also occurs. The concentration of polar adsorption sites therefore determines the hydrophilicity of the carbon structure and their accelerated formation, by exposure to air and water vapour, is also responsible for the 'ageing' of active carbons. Overall, the adsorption of water reduces the volume of porosity available for the adsorption of target species and the hydrophilic nature of active carbons is recognized as a major barrier to their effective use in many applications. We present here results for the adsorption of nitrogen, organic and water vapours by a hydrophobic respirator granular active carbon produced by the thermal treatment of a base carbon, to desorb polar oxygen groups, followed by use of a plasma enhanced chemical vapour deposition (PECVD) treatment to apply a hydrophobic, fluorine containing, surface nanolayer. We show that at equivalent %RH values the treated carbon adsorbs significantly less water compared to an untreated (control) carbon and that the treatment does not reduce the levels of open porosity or impede the adsorption of a range of organic vapours at ambient temperatures. Preliminary evidence for the presence, after treatment, of constrictions at pore entrances which act as molecular gates is also presented. The treated carbon (after ageing for 6 weeks at 80%RH) is shown to have greater adsorptivity than an untreated base carbon toward hexane present in a humid (80%RH) airstream. This results in a 39% increase in break-through time. These hydrophobic properties persist one year after manufacture. The mechanism leading to the modified water adsorption properties is the partial desorption of polar oxygen sites followed by deposition at the external carbon surfaces of hydrophobic plasma polymer species. This reduces the polar surface free energy of the carbon and hence the amount of water adsorption occurring by the primary mechanism. This in turn retards the diffusion of water molecules into the micropores and leads to lower adsorption volumes at higher pressures.

Bradley, Robert H.; Smith, Martin W.; Andreu, Aurik; Falco, Maurizio

2011-01-01

137

Active Processes in Insect Hearing  

Microsoft Academic Search

Active mechanical processes in hearing are not restricted to vertebrates: as shown by recent research, such processes are found in insects as well. The investigation of these amplificatory processes in insect hearing has scarcely begun. Many questions are outstanding, including perhaps the most intriguing one, that is, whether, reflecting the need for sensitive hearing, the mechanisms that effect active amplification

Martin C. Göpfert; Daniel Robert

138

Carbonate Beaches: A Balance Between Biological and Physical Processes  

Microsoft Academic Search

Carbonate beaches are a unique example of the interaction between biological processes, creating the sediments, and physical processes, moving and often removing the sediments. On the sediment supply side, carbonate sediments are born, not made. They exist in dynamic equilibrium between production and destruction. Following the creation of carbonate sediment in coral reef and lagoon environments, the sediments are moved

R. Nairn; M. Risk

2004-01-01

139

Process for reducing carbon monoxide emissions from regenerators of catalytic cracking units  

Microsoft Academic Search

Catalytic cracking processes are improved by employing cracking catalyst particles containing rare earth components spray impregnated thereon. In comparison to other rare earth-promoted cracking catalysts, the cracking catalysts of the invention exhibit greater activity for oxidizing carbon monoxide to carbon dioxide during the regeneration step of the cracking process wherein coke-containing catalyst particles are reactivated for cracking hydrocarbons by combustion

Baron

1981-01-01

140

Studies relevant to the catalytic activation of carbon monoxide  

SciTech Connect

Research activity has included continued mechanistic investigations of the nucleophilic activation of carbon monoxide such as homogeneous catalysis of the water gas shift and key steps in the relevant catalytic cycles. Other investigations of related processes included the application of fast reaction techniques to prepare and to investigate quantitatively reactive organometallic intermediates relevant to the activation of hydrocarbons toward carbonylation and other functionalizations. 8 refs.

Ford, P.C.

1991-09-04

141

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

NASA Astrophysics Data System (ADS)

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.

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

2013-09-01

142

Retreat of carbonate platforms: Response to tectonic processes  

SciTech Connect

A SeaMARC 2 and seismic reflection investigation of the deep-water margins of carbonate banks in the southeast Bahamas has documented the retreat of these isolated platforms since mid-Cretaceous time. This retreat is in sharp contrast to prograding carbonate platforms in the passive northwest Bahamas and provides an initial framework within which to view the response of carbonate platforms to tectonic processes. Processes of retreat include large-scale (50-60 km) step-back to platform margins during the mid-Cretaceous; tectonic subsidence and downfaulting during the late Tertiary; and large-scale collapse of platform margins, which may be an active process. Step-back during the mid-Cretaceous correlates with a global tectonic pulse of ocean-crust formation and relative sea-level rise; downfaulting may be a response to either late Tertiary lithospheric bending during subduction and/or block rotation along the North American-Caribbean plate boundary; and collapse may be related to earthquake shocks generated by active plate-tectonic collision between the southwest Bahamas and Hispaniola.

Mullins, H.T.; Andersen, B.; Gaylord, M.; Petruccione, J.L.; Wellner, R.W. (Syracuse Univ., NY (United States)); Dolan, J. (California Inst. of Tech., Pasadena (United States)); Breen, N. (Stanford Univ., CA (United States)); Melillo, A.J.; Jurgens, A.D. (Chevron U.S.A., New Orleans, LA (United States))

1991-11-01

143

Preparation and characterization of activated carbon from pistachio nut shells via microwave-induced chemical activation  

Microsoft Academic Search

In this work, pistachio nut shell, a biomass residue abundantly available from the pistachio nut processing industries, was utilized as a feedstock for the preparation of activated carbon (PSAC) via microwave assisted KOH activation. The activation step was performed at the microwave input power of 600 W and irradiation time of 7 min. The porosity, functional and surface chemistry were featured by

K. Y. Foo; B. H. Hameed

2011-01-01

144

Use of granulated activated carbon at the Oak Ridge Y-12 Plant Central Pollution Control facility  

Microsoft Academic Search

There are few industrial waste treatment processes that do not include some form of fixed bed activated carbon adsorption for removal of organic contaminants. This processes is especially important when the effluent of a treatment process is discharged to a natural water receiving stream for which environmental quality is considered important. In some treatment processes carbon adsorption comprises the heart

Gilpin

1991-01-01

145

Comparative study of heavy metal ions sorption onto activated carbon, carbon nanotubes, and carbon-encapsulated magnetic nanoparticles  

Microsoft Academic Search

The paper presents the advantages and limitations of heavy metals sorption onto three different carbon materials: activated carbon, carbon nanotubes, and carbon-encapsulated magnetic nanoparticles. Studied carbon sorbents differed with the grain size, crystallinity, and active surface area, which were derived from electron microscopy, Raman spectroscopy, and methylene blue adsorption, respectively. Detailed sorption studies were based on two model metal ions,

Krystyna Pyrzy?ska; Micha? Bystrzejewski

2010-01-01

146

Process to minimize cracking of pyrolytic carbon coatings  

DOEpatents

Carbon-coated microspheroids useful as fuels in nuclear reactors are produced with a low percentage of cracked coatings and are imparted increased strength and mechanical stability characteristics by annealing immediately after the carbon coating processes.

Lackey, Jr., Walter J. (Oak Ridge, TN); Sease, John D. (Knoxville, TN)

1978-01-01

147

TWO-STAGE GRANULAR ACTIVATED CARBON TREATMENT  

EPA Science Inventory

Two 6.3 l/sec (0.15 mgd), two-stage, packed-bed, downflow granular activated carbon pilot plants were operated continuously for 33 months using unfiltered and unchlorinated activated sludge plant effluent. The main objective of the study was to compare the performance of granular...

148

Adsorption of Mercuric Ion from Aqueous Solutions Using Activated Carbon  

Microsoft Academic Search

Activated carbon (AC) was prepared from hazelnut shells using two steps of carbonization followed by steam activation. Methylene blue dye was used as a probe for evaluation of the prepared activated carbon. In order to have a better comparison, a commercial grade of activated carbon (powdered) obtained from the Merck Company has also been used in this research as standard.

R. Ansari Khalkhali; R. Omidvari

149

Pesticide removal by combined ozonation and granular activated carbon filtration  

Microsoft Academic Search

Since the seventies, new water treatment processes have been introduced in the production of drinking water from surface water. Their major aim was to adequately cope with the disinfection of this water, and\\/or with the removal of pesticides and other organic micropollutants from it. This research focused on Biological Activated Carbon (BAC) filtration, which is a combination of ozonation and

E. Orlandini

1999-01-01

150

ADSORPTION OF PROTEINS ONTO ACTIVATED CARBON AND PHENOLIC RESIN  

Microsoft Academic Search

Adsorption of BSA lysozyme and mixture of the two proteins from aqueous solution onto activated carbon and adsorption of BSA onto phenolic resin has been studied to develop design parameters for protein adsorption and to evaluate the effective diffusivity of the proteins. The findings then are used as the theoretical basis for the study of processes such as enzyme immobilization

REI-YOUNG AMOS WU

1982-01-01

151

Reprocessing of used tires into activated carbon and other products  

Microsoft Academic Search

Landfilling used tires which are generated each year in the US is increasingly becoming an unacceptable solution. A better approach, from an environmental and economic standpoint, is to thermally reprocess the tires into valuable products such as activated carbon, other solid carbon forms (carbon black, graphite, and carbon fibers), and liquid fuels. In this study, high surface area activated carbons

Hsisheng Teng; Michael A. Serio; Marek A. Wojtowicz; Rosemary Bassilakis; Peter R. Solomon

1995-01-01

152

Removal of phenol from aqueous solution using carbonized Terminalia chebula-activated carbon: process parametric optimization using conventional method and Taguchi's experimental design, adsorption kinetic, equilibrium and thermodynamic study  

NASA Astrophysics Data System (ADS)

In the present paper, the phenol removal from wastewater was investigated using agri-based adsorbent: Terminalia chebula-activated carbon (TCAC) produced by carbonization of Terminalia chebula (TC) in air-controlled atmosphere at 600 °C for 4 h. The surface area of TCAC was measured as 364 m2/g using BET method. The surface characteristic of TCAC was analyzed based on the value of point of zero charge. The effect of parameters such as TCAC dosage, pH, initial concentration of phenol, time of contact and temperature on the sorption of phenol by TCAC was investigated using conventional method and Taguchi experimental design. The total adsorption capacity of phenol was obtained as 36.77 mg/g using Langmuir model at the temperature of 30 °C at pH = 5.5. The maximum removal of phenol (294.86 mg/g) was obtained using Taguchi's method. The equilibrium study of phenol on TCAC showed that experimental data fitted well to R-P model. The results also showed that kinetic data were followed more closely the pseudo-first-order model. The results of thermodynamic study showed that the adsorption of phenol on TCAC was spontaneous and an exothermic in nature.

Khare, Prateek; Kumar, Arvind

2012-12-01

153

Kinetic study of platinum sorption from solutions by active carbons  

SciTech Connect

The purpose of this work was to study the kinetics of sorption of platinum compounds from hydrochloric acid solutions by active carbons, to identify the controlling step of mass transfer during sorption, and to formulate a mathematical model of the kinetics of the given process. Experimental study of the kinetics of sorption of (PtCl/sub 6/)/sup 2 -/ anions from hydrochloric acid solutions by SKS-3 and SKN-2M artificial active carbons showed that the controlling step is mass transfer by internal diffusion.

Bagreev, A.A.; Tarasenko, Yu.A.; Mardanenko, V.K.; Potyazhenko, I.A.

1988-07-20

154

The CNG process: Acid gas removal with liquid carbon dioxide  

SciTech Connect

The CNG acid gas removal process has two unique features: the absorption of sulfur-containing compounds and other trace contaminants with liquid carbon dioxide, and the regeneration of pure liquid carbon dioxide by triple-point crystallization. The process is especially suitable for treating gases which contain large amounts of carbon dioxide and much smaller amounts (relative to carbon dioxide) of hydrogen sulfide. Capital and energy costs are lower than conventional solvent processes. Further, products of the CNG process meet stringent purity specifications without undue cost penalties. A process demonstration unit has been constructed and operated to demonstrate the two key steps of the CNG process. Hydrogen sulfide and carbonyl sulfide removal from gas streams with liquid carbon dioxide absorbent to sub-ppm concentrations has been demonstrated. The production of highly purified liquid carbon dioxide (less than 0.1 ppm total contaminant) by triple-point crystallization also has been demonstrated.

Liu, Y.C.; Auyang, L.; Brown, W.R.

1987-01-01

155

Removal of bromate ion using powdered activated carbon.  

PubMed

Bromate ion (BrO3-) removal from drinking water by powdered activated carbons (PACs) in bath mode was evaluated under various operational conditions. Six kinds of PACs, including wood-based carbon, fruit-based carbon, coal-based carbon, and these three carbons thermally deoxidized in a nitrogen atmosphere, were selected to investigate their capacity on BrO3- removal. With the highest zeta potential value and being richly mesoporous, coal-based carbon had a high and an excellent BrO3- adsorption efficiency. The removal content of BrO3- by per gram of coal-based carbon was 0.45 mg within 5 hr in 100 microg/L bromate solution. The surface characteristics of PACs and bromide formation revealed that both physical and chemical PACs properties simultaneously affected the adsorption-reduction process. Under acidic conditions, PACs possessed high zeta value and adequate basic groups and exhibited neutral or positive charges, promoting BrO3- adsorption-reduction on the carbon surface. Interestingly, the PACs thermally deoxidized in N2 atmosphere optimized their properties, e.g. increasing their zeta values and decreasing the oxygen content which accelerated the BrO3- removal rate. The maximum adsorption capacity of fruit-based carbon was the highest among all tested carbons (99.6 mg/g), possibly due to its highest pore volume. Remarkably, the thermal regeneration of PACs in N2 atmosphere could completely recover the adsorption capacity of PACs. The kinetic data obtained from carbons was analyzed using pseudo second-order and intraparticle diffusion models, with results showing that the intraparticle diffusion was the more applicable model to describe adsorption of BrO3- onto PACs. PMID:21462700

Wang, Lian; Zhang, Jie; Liu, Jingze; He, Hong; Yang, Min; Yu, Jianwei; Ma, Zichuan; Jiang, Feng

2010-01-01

156

The dry carbonate process: Carbon dioxide recovery from power plant flue gas  

Microsoft Academic Search

RTI’s Dry Carbonate Process, a solid sorbent CO2 capture approach, has been developed as a retrofit technology for existing power plants. The process is based on the reversible reaction between sodium carbonate, CO2, and water vapor to form sodium bicarbonate. Concentrated CO2 is recovered by a thermal-swing process. Field testing of a prototype Dry Carbonate Process has been completed with

Thomas O. Nelson; Luke J. I. Coleman; David A. Green; Raghubir P. Gupta

2009-01-01

157

Record Methane Storage in Monolithic and Powdered Activated Carbons  

Microsoft Academic Search

The Alliance for Collaborative Research in Alternative Fuel Technology (ALL-CRAFT) has developed activated carbons from corn cob as adsorbent materials for methane gas storage by physisorption at low pressures. KOH activated carbons were compressed into carbon monolith using chemical binders. High pressure methane isotherms up to 250 bar at room temperature on monolithic and powdered activated carbons were measured gravimetrically

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

2010-01-01

158

40 CFR 458.20 - Applicability: description of the carbon black thermal process subcategory.  

Code of Federal Regulations, 2010 CFR

...Applicability: description of the carbon black thermal process subcategory...EFFLUENT GUIDELINES AND STANDARDS CARBON BLACK MANUFACTURING POINT SOURCE CATEGORY Carbon Black Thermal Process Subcategory...

2009-01-01

159

40 CFR 458.40 - Applicability; description of the carbon black lamp process subcategory.  

Code of Federal Regulations, 2013 CFR

...Applicability; description of the carbon black lamp process subcategory. 458...GUIDELINES AND STANDARDS (CONTINUED) CARBON BLACK MANUFACTURING POINT SOURCE CATEGORY Carbon Black Lamp Process Subcategory §...

2013-07-01

160

40 CFR 458.30 - Applicability; description of the carbon black channel process subcategory.  

Code of Federal Regulations, 2010 CFR

...Applicability; description of the carbon black channel process subcategory...EFFLUENT GUIDELINES AND STANDARDS CARBON BLACK MANUFACTURING POINT SOURCE CATEGORY Carbon Black Channel Process Subcategory...

2009-01-01

161

40 CFR 458.30 - Applicability; description of the carbon black channel process subcategory.  

Code of Federal Regulations, 2010 CFR

...Applicability; description of the carbon black channel process subcategory...EFFLUENT GUIDELINES AND STANDARDS CARBON BLACK MANUFACTURING POINT SOURCE CATEGORY Carbon Black Channel Process Subcategory...

2010-07-01

162

40 CFR 458.20 - Applicability: description of the carbon black thermal process subcategory.  

Code of Federal Regulations, 2010 CFR

...Applicability: description of the carbon black thermal process subcategory...EFFLUENT GUIDELINES AND STANDARDS CARBON BLACK MANUFACTURING POINT SOURCE CATEGORY Carbon Black Thermal Process Subcategory...

2010-07-01

163

40 CFR 458.40 - Applicability; description of the carbon black lamp process subcategory.  

Code of Federal Regulations, 2010 CFR

...Applicability; description of the carbon black lamp process subcategory. 458...EFFLUENT GUIDELINES AND STANDARDS CARBON BLACK MANUFACTURING POINT SOURCE CATEGORY Carbon Black Lamp Process Subcategory §...

2010-07-01

164

40 CFR 458.10 - Applicability; description of the carbon black furnace process subcategory.  

Code of Federal Regulations, 2010 CFR

...Applicability; description of the carbon black furnace process subcategory...EFFLUENT GUIDELINES AND STANDARDS CARBON BLACK MANUFACTURING POINT SOURCE CATEGORY Carbon Black Furnace Process Subcategory...

2009-01-01

165

40 CFR 458.10 - Applicability; description of the carbon black furnace process subcategory.  

Code of Federal Regulations, 2013 CFR

...Applicability; description of the carbon black furnace process subcategory...GUIDELINES AND STANDARDS (CONTINUED) CARBON BLACK MANUFACTURING POINT SOURCE CATEGORY Carbon Black Furnace Process Subcategory...

2013-07-01

166

40 CFR 458.20 - Applicability: description of the carbon black thermal process subcategory.  

Code of Federal Regulations, 2013 CFR

...Applicability: description of the carbon black thermal process subcategory...GUIDELINES AND STANDARDS (CONTINUED) CARBON BLACK MANUFACTURING POINT SOURCE CATEGORY Carbon Black Thermal Process Subcategory...

2013-07-01

167

40 CFR 458.10 - Applicability; description of the carbon black furnace process subcategory.  

Code of Federal Regulations, 2010 CFR

...Applicability; description of the carbon black furnace process subcategory...EFFLUENT GUIDELINES AND STANDARDS CARBON BLACK MANUFACTURING POINT SOURCE CATEGORY Carbon Black Furnace Process Subcategory...

2010-07-01

168

40 CFR 458.30 - Applicability; description of the carbon black channel process subcategory.  

Code of Federal Regulations, 2013 CFR

...Applicability; description of the carbon black channel process subcategory...GUIDELINES AND STANDARDS (CONTINUED) CARBON BLACK MANUFACTURING POINT SOURCE CATEGORY Carbon Black Channel Process Subcategory...

2013-07-01

169

40 CFR 458.40 - Applicability; description of the carbon black lamp process subcategory.  

Code of Federal Regulations, 2010 CFR

...Applicability; description of the carbon black lamp process subcategory. 458...EFFLUENT GUIDELINES AND STANDARDS CARBON BLACK MANUFACTURING POINT SOURCE CATEGORY Carbon Black Lamp Process Subcategory §...

2009-01-01

170

Processing and characterization of monolithic carbon structures based on wood fiberboards  

NASA Astrophysics Data System (ADS)

The structure and properties of monolithic carbonized medium-density fiberboards were studied to expand the capabilities of carbonized wood processing. Medium-density fiberboard (MDF) has a more uniform structure than wood, which was investigated in earlier studies for monolithic carbon structures. The uniform structure of medium density fiberboard (MDF) allowed for a reduction in thermal processing time from 4.5 days for wood carbonization to 1 day for MDF carbonization. Key physical properties of carbonized MDF (c-MDF) were determined for potential applications, such as battery electrodes, fuel cell separators and activated carbon filters. X-ray diffraction (XRD) was used to characterize the growth of large turbostratic crystallites and large graphene sheets during the carbonization process. A novel x-ray diffraction method using monolithic pieces of c-MDF was used to correlate the dimensional changes occurring during the carbonization process with the growth of large turbostratic crystallites. The insights gained from the XRD investigation of c-MDF were used to develop a quasipercolation model, which describes the microstructural evolution of hard carbons. This quasipercolation model explained the observed changes in bulk density, dimension, helium density and electrical conductivity of c-MDF. The model also explained how nanopores form in activated carbon materials. The mechanical and electrical properties of carbonized MDF were measured using ASTM 4-point bending and 4-point electrical conductivity techniques. The elastic modulus was shown to vary from 1.5 to 4.5 GPa for the carbonization temperature range of 600°C to 1000°C. The electrical resistivity varied by seven orders of magnitude from 600°C to 1400°C. An open foam model was used to approximate the mechanical and electrical properties of the hard carbon material in the porous c-MDF. Large structural activated carbons were made by physical activation of c-MDF in carbon dioxide. A low activation temperature was used to uniformly activate the porous c-MDF structure. Activated carbonized MDF achieved a BET surface area of approximately 1000 m2/g. Mechanical properties of activated c-MDF showed that these materials can be activated without significantly reducing their mechanical integrity.

Kercher, Andrew Keith

171

Carbon-Based Supercapacitors Produced by Activation of Graphene  

SciTech Connect

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.

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

172

Carbon-based Supercapacitors Produced by Activation of Graphene  

SciTech Connect

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.

Y Zhu; S Murali; M Stoller; K Ganesh; W Cai; P Ferreira; A Pirkle; R Wallace; K Cychosz; et al.

2011-12-31

173

Study of NO adsorption on activated carbons  

Microsoft Academic Search

Activated carbons (ACs) with varied porous textures and surface chemistry were studied for NO removal under different test conditions at temperatures below 100°C. When oxygen is absent, there is almost no NO removal. When oxygen is present ACs act both as a catalyst for NO oxidation and as an adsorbent for NO adsorption. NO conversion is correlated with the presence

W. J. Zhang; S. Rabiei; A. Bagreev; M. S. Zhuang; F. Rasouli

2008-01-01

174

ACTIVATED CARBON TREATMENT OF KRAFT BLEACHING EFFLUENTS  

EPA Science Inventory

The removal of color and organic contaminants by adsorption on activated carbon from the effluent of a kraft pulp bleaching plant was investigated in a pilot plant. The caustic bleach effluent, which contains 80% of the color from pulp bleaching, was decolorized successfully when...

175

Low frequency sound propagation in activated carbon.  

PubMed

Activated carbon can adsorb and desorb gas molecules onto and off its surface. Research has examined whether this sorption affects low frequency sound waves, with pressures typical of audible sound, interacting with granular activated carbon. Impedance tube measurements were undertaken examining the resonant frequencies of Helmholtz resonators with different backing materials. It was found that the addition of activated carbon increased the compliance of the backing volume. The effect was observed up to the highest frequency measured (500 Hz), but was most significant at lower frequencies (at higher frequencies another phenomenon can explain the behavior). An apparatus was constructed to measure the effective porosity of the activated carbon as well as the number of moles adsorbed at sound pressures between 104 and 118 dB and low frequencies between 20 and 55 Hz. Whilst the results were consistent with adsorption affecting sound propagation, other phenomena cannot be ruled out. Measurements of sorption isotherms showed that additional energy losses can be caused by water vapor condensing onto and then evaporating from the surface of the material. However, the excess absorption measured for low frequency sound waves is primarily caused by decreases in surface reactance rather than changes in surface resistance. PMID:22779473

Bechwati, F; Avis, M R; Bull, D J; Cox, T J; Hargreaves, J A; Moser, D; Ross, D K; Umnova, O; Venegas, R

2012-07-01

176

Sorption of elemental mercury by activated carbons  

SciTech Connect

The paper gives results of a study of the mechanisms and rate of elemental mercury (Hg) capture by activated carbons, using a bench-scale apparatus. Three types of activated carbons, two thermally activated (PC-100 and FGD) and one impregnated with elemental sulfur (S) (HGR), were used to study the effects of surface area (approximately 550-1000 sq m/g), sorption temperature (23-140 C), and elemental Hg concentration (30 and 60 ppb of elemental Hg in nitrogen). Investigations revealed that sorption occurs in active sites in PC-100 and FGD which are either depleted or deactivated at 140 C. Desorption studies for PC-100 and HGR revealed the sorption mechanism to be a combination of physisorption and chemisorption at 23 C, whereas chemisorptionis the primary route at 140 C.

Krishnan, S.V.; Gullett, B.K.; Jozewicz, W.

1994-01-01

177

Hydrogen adsorption on modified activated carbon  

Microsoft Academic Search

The aim of this work is to investigate hydrogen adsorption on prepared super activated carbon (AC). Litchi trunk was activated by potassium hydroxide under N2 or CO2 atmosphere. Nanoparticles of palladium were impregnated in the prepared-AC. Hydrogen adsorption was accurately measured by a volumetric adsorption apparatus at 77, 87, 90 and 303K, up to 5MPa. Experimental results revealed that specific

Chen-Chia Huang; Hsiu-Mei Chen; Chien-Hung Chen

2010-01-01

178

Process for removing carbonate from wells  

SciTech Connect

This patent describes a method of removing carbonate deposited in a water supply well by inflowing groundwater. It comprises: treating a supply of water by means of a membrane system for desalinization which places the water in an aggressive state of chemical inequilibrium and ion imbalance having a keen affinity for carbonate; pumping a fluid comprising the treated supply of water, without restabilization, into the well to react with the deposited carbonate; and flushing the product of the reaction from the well.

Derowisch, R.W.

1989-11-14

179

Supercapacitor Electrodes from Activated Carbon Monoliths and Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

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.

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

2013-04-01

180

Cluster Ion Implantation for Process Application -Carbon Cluster co-Implantation-  

NASA Astrophysics Data System (ADS)

For beyond 32 nm NMOS device fabrication, Cluster Carbon co-implantation process is experimentally evaluated. It is found that using Cluster Carbon co-implantation, instead of Ge PAI plus single Carbon co-implantation, Phosphorus (P) TED was suppressed and the junction depth Xj are reduced by 10 nm for SDE condition and by 17 nm for SD condition when the Cluster Carbon effective dose 2×1015/cm2. The sheet resistivity Rs of 280 ?/sq for SDE condition is increased with the increment of the Carbon dose, but the Rs×Xj product 7156 ?/sq.nm has a minimum value is confirmed. The difference of the Cluster Carbon co-implantation to the monomer Carbon implantation is evaluated and the Cluster Carbon PAI effect makes higher activation of the P dopnt after annealing.

Tanjyo, M.; Nagayama, T.; Onoda, H.; Hamamoto, N.; Umisedo, S.; Koga, Y.; Une, H.; Maehara, N.; Kawamura, Y.; Hashino, Y.; Nakashima, Y.; Hashimoto, M.; Tokoro, N.; Nagai, N.; Sekar, K.; Krull, W.

2011-01-01

181

Thermal regeneration of granular activated carbons using inert atmospheric conditions.  

PubMed

Thermal regeneration is increasingly being used for the recovery of field-spent granular activated carbons (GAC) generated by the water treatment industry. Despite its commercial success, conventional methods using oxidising conditions (usually steam) are known to damage the porosity of the regenerated carbons, thus reducing their adsorption capacity and economic value. This paper presents a comparative investigation into the benefits of using inert conditions for the regeneration of field-spent GAC. For the purpose of this work, a sample of spent carbon was regenerated in nitrogen and in steam to different degrees of burn off. The resulting samples were analysed for their porosity and surface area characteristics using nitrogen gas adsorption, and for their aqueous adsorption capacities using phenol and methylene blue. Experimental results showed that steam was sightly more effective than nitrogen at regenerating the total micropore volume and BET surface area of the carbons. However, these benefits were largely counteracted by greater losses in the carbon yield and damage to the narrow microporosity. Carbons regenerated in nitrogen exhibited greater adsorption capacities for the adsorption of small molecular size compounds (phenol) from solution, while carbons regenerated in steam adsorbed larger molecular size compounds (methylene blue) more effectively. However, when product yields were taken into consideration, inert regeneration was found to produce significantly better results than steam regeneration. An optimum process temperature was determined to be 950 degrees C. PMID:12523505

San Miguel, G; Lambert, S D; Graham, N J D

2002-12-01

182

Process for removing carbon from uranium  

DOEpatents

Carbon contamination is removed from uranium and uranium alloys by heating in inert atmosphere to 700.degree.-1900.degree.C in effective contact with yttrium to cause carbon in the uranium to react with the yttrium. The yttrium is either in direct contact with the contaminated uranium or in indirect contact by means of an intermediate transport medium.

Powell, George L. (Oak Ridge, TN); Holcombe, Jr., Cressie E. (Knoxville, TN)

1976-01-01

183

Synthesis of carbon nanbotubes by plasma-enhanced CVD process: gas phase study of synthesis conditions  

NASA Astrophysics Data System (ADS)

To support experimental investigations, a model based on Chemkin^TM software was used to simulate gas phase and surface chemistry during plasma-enhanced catalytic CVD of carbon nanotubes. According to these calculations, gas phase composition, etching process and growth rates are calculated. The role of several carbon species, hydrocarbon molecules and ions in the growth mechanism of carbon nanotubes is presented in this study. Study of different conditions of gas phase activation sources and pressure is performed.

Guláš, M.; Cojocaru, C. S.; Fleaca, C. T.; Farhat, S.; Veis, P.; Le Normand, F.

2008-09-01

184

Catalytic wet air oxidation of phenol with modified activated carbons and Fe\\/activated carbon catalysts  

Microsoft Academic Search

A commercial activated carbon was modified by different oxidative treatments to introduce different oxygen surface groups. A gentle oxidation in gas phase with a poor oxygen stream and a more severe oxidation in liquid phase with a HNO3 solution were used. The resulting activated carbons and the corresponding Fe-impregnated (2.5% Fe) ones were tested for the wet air oxidation of

A. Quintanilla; J. A. Casas; J. J. Rodríguez

2007-01-01

185

Production of Activated Carbon from Date Stones by Using Zinc Chloride  

Microsoft Academic Search

Production of activated carbon from date stones by chemical activation with zinc chloride (ZnCl2) was experimentally investigated using a laboratory-scale fluidized-bed reactor. The effects of process variables, such as activation time, activation temperature, impregnation ratio, and particle size, on the production and quality of activated carbon were measured in terms of adsorptive capacity by iodine number test. An activation time

F. A. H. Al-Qaessi

2010-01-01

186

Optimization of the Preparation Conditions for Activated Carbons from Sugarcane Bagasse: An Agricultural Waste  

Microsoft Academic Search

The low-cost activated carbon was prepared from sugarcane bagasse, an agricultural waste material, by chemical activation with different reagents. Orthogonal experimental design was applied to study the influence of activation temperature, activation time and chemical ratio of reagents to sugarcane bagasse on the chemical activation process of sugarcane bagasse. The optimal activated carbon was obtained using impregnation ratio of 0.39-0.78%

Zelong Xu; Yinian Zhu; Meina Liang; Hua Zhang; Huili Liu

2011-01-01

187

Transition metal-catalyzed process for addition of amines to carbon-carbon double bonds  

DOEpatents

The present invention is directed to a process for addition of amines to carbon-carbon double bonds in a substrate, comprising: reacting an amine with a compound containing at least one carbon-carbon double bond in the presence a transition metal catalyst under reaction conditions effective to form a product having a covalent bond between the amine and a carbon atom of the former carbon-carbon double bond. The transition metal catalyst comprises a Group 8 metal and a ligand containing one or more 2-electron donor atoms. The present invention is also directed to enantioselective reactions of amine compounds with compounds containing carbon-carbon double bonds, and a calorimetric assay to evaluate potential catalysts in these reactions.

Hartwig, John F. (Durham, CT); Kawatsura, Motoi (Chatham, NJ); Loeber, Oliver (New Haven, CT)

2002-01-01

188

Development technique in the activation process of petroleum coke  

SciTech Connect

The manufacture of activated carbon involves two main stages, the carbonization of the carbonaceous precursor and the activation of the resulting char. Process activation is to enhance the pore structure by the partial gasification of the char in steam, carbon dioxide, air or a mixture of these; this is the so-called {open_quotes}physical activation{close_quotes}. The term {open_quotes}chemical activation{close_quote} refers to the carbonization of the precursors after addition of substances that restrict the formation of tar (H{sub 3}PO{sub 4}, KOH, etc); in this way, a carbonized product with a well developed porosity (after appropriate washing) may be obtained in a single operation. There is, of course, the possibility of combining these two activation processes. In our experiments, the two principal methods of activation, i.e., that which uses CO{sub 2} and that which uses KOH were chosen and treated to green petroleum coke as starting materials. The properties such as surface area and Iodine adsorption were relatively low in the physical activation. The surface area was reached in the range of 27 to 79 m{sup 2}/g and Iodine adsorption 59 to 135 mg/g. The adsorptive power in Iodine solutions increased to the value of approximate 600 mg/g for physical activation of green coke binded with tar pitch. Furthermore, a well developed in pore, surface area and Iodine adsorption was achieved using KOH activant with appropriate process condition.

Pudiyanto, T.I.; Nurlatifah, S. [PERTAMINA, Jakarta (Indonesia)

1996-12-31

189

Preparation of High Surface Area Mesoporous Activated Carbon: Kinetics and Equilibrium Isotherm  

Microsoft Academic Search

Activated carbon prepared from palm shell by phosphoric acid impregnation, at significantly favorable experimental conditions is characterized for the porous nature and adsorption of methylene blue dye molecules. The activation is carried out using a 2-stage activation process with the activation in a self generated atmosphere. An activation temperature of 500 °C, with an activation time of 75 minutes using

W. C. Lim; C. Srinivasakannan; V. Doshi

2012-01-01

190

Influences of influent carbon source on extracellular polymeric substances (EPS) and physicochemical properties of activated sludge  

Microsoft Academic Search

It is necessary to understand the bioflocculation, settling and dewatering characteristics in the activated sludge process in order to establish more efficient operational strategies. The influences of carbon source on the extracellular polymeric substances (EPS) and flocculation, settling and dewatering properties of the activated sludge were investigated. Laboratory-scale completely mixed activated sludge processes were used to grow the activated sludge

FenXia Ye; Ge Peng; Ying Li

2011-01-01

191

The production of chemically-activated carbon  

Microsoft Academic Search

In an attempt to optimise the microporosity in an activated carbon, controlled heating of sucrose chars and other precursor materials was carried out in an inert environment with an excess of potassium or sodium hydroxide. Initially, the precursor materials were subjected to a regulated temperature–time profile to elevated temperatures (400–900°C) and subsequently cooled. The products were then exposed either to

M. J. B Evans; E Halliop; J. A. F MacDonald

1999-01-01

192

Palladium catalysts on activated carbon supports  

Microsoft Academic Search

A number of activated carbons produced from peat, coconut shell, and by pyrolysis of hydrocarbons have been subjected to treatment with oxygen, chlorine, hydrogen or ammonia at elevated temperatures to get a representative series of catalyst supports differing in porous structure and surface chemistry (characterized by nitrogen adsorption and selective titrations). Palladium was deposited from anionic (H2PdCl4), neutral (Pd(OAc)2, in

M. Gurrath; T. Kuretzky; H. P. Boehm; L. B. Okhlopkova; A. S. Lisitsyn; V. A. Likholobov

2000-01-01

193

Elimination of carcinogens (excluding haloforms) from water by active carbon  

Microsoft Academic Search

Elimination of carcinogens (excluding haloforms) from water by active carbon was studied in the laboratory. Ten activated carbons were tested for their ability to adsorb eight different polycyclic aromatic hydrocarbons (PAH). The PAH were introduced in acetone solution to synthetic sewage water. Activated carbon concentration was 1 g\\/l. and contact time was 30 min at 15° with a 500 rpm

Borneff

1978-01-01

194

Continuous supercritical carbon dioxide processing of palm oil  

Microsoft Academic Search

Crude palm oil was processed by continuous supercritical carbon dioxide. The process reduces the contents of free fatty acids,\\u000a monoglycerides and diglycerides, certain triglycerides, and some carotenes. The refined palm oil from the process has less\\u000a than 0.1% free fatty acids, higher carotene content, and low diglycerides. Solubility of palm oil in supercritical carbon\\u000a dioxide increased with pressure. A co-solvent

C. K. Ooi; A. Bhaskar; M. S. Yener; D. Q. Tuan; J. Hsu; S. S. H. Rizvi

1996-01-01

195

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

PubMed

Polyvinylchloride (PVC) was successfully recycled through the solvent extraction from waste pipe with an extraction yield of ca. 86%. The extracted PVC was pyrolyzed by a two-stage process (260 and 410 degrees C) to obtain free-chlorine PVC based pitch through an effective removal of chlorine from PVC during the heat-treatment. As-prepared pitch (softening point: 220 degrees C) was spun, stabilized, carbonized into carbon fibers (CFs), and further activated into activated carbon fibers (ACFs) in a flow of CO2. As-prepared CFs show comparable mechanical properties to commercial CFs, whose maximum tensile strength and modulus are 862 MPa and 62 GPa, respectively. The resultant ACFs exhibit a high surface area of 1200 m2/g, narrow pore size distribution and a low oxygen content of 3%. The study provides an effective insight to recycle PVC from waste PVC and develop a carbon precursor for high performance carbon materials such as CFs and ACFs. PMID:17157493

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

2006-12-08

196

A simulation study of the removal efficiency of granular activated carbon on cadmium and lead  

Microsoft Academic Search

The excessive release of heavy metals into the environment is a major concern worldwide. Adsorption process is among the most effective techniques for heavy metals removal from waste streams and activated carbon has been widely used as an adsorbent. Therefore, this study was carried out to examine the potential and effectiveness of granular activated carbon (GAC) to remove heavy metals,

Ahmad Jusoh; Lam Su Shiung; Nora’aini Ali; M. J. M. M. Noor

2007-01-01

197

Sorption of boric acid and borax by activated carbon impregnated with various compounds  

Microsoft Academic Search

The separation of boron compounds, boric acid and borax from aqueous solution by activated carbon before and after impregnation with various compounds was studied. A series of activated carbons was prepared from coconut shell impregnated with calcium and barium chlorides, citric and tartaric acids. The examined processes were performed in batch and continuous systems under equilibrium and dynamic conditions. Impregnation

Lj. V. Rajakovi?; M. Dj. Risti?

1996-01-01

198

Role of the activated carbon surface chemistry in the adsorption of phenanthrene  

Microsoft Academic Search

The influence of the surface chemistry in the adsorption of Phenanthrene (Phe) vapor on oxidized activated carbons has been studied. All the runs were performed in a fixed bed reactor with a process temperature of 150 °C, similar to the observed in the flue gases from energy generation systems. A commercial activated carbon was chosen as raw material. The oxidized

T Garc??a; R Murillo; D Cazorla-Amorós; A. M Mastral; A Linares-Solano

2004-01-01

199

Cold catalytic recovery of loaded activated carbon using iron oxide-based nanoparticles  

Microsoft Academic Search

A novel approach for the recovery of spent activated carbon by an advanced oxidation process using iron oxide-based nanocatalysts was proposed and investigated. Model organic contaminants, such as ethylene glycol and phenol, were chosen for this study as water pollutants. It was shown that there are several advantages in using catalytic oxidation recovery of activated carbon with iron oxide-based nanocatalysts:

Altai Bach; Grigory Zelmanov; Raphael Semiat

2008-01-01

200

Structure evolution and optimization in the fabrication of PVA-based activated carbon fibers  

Microsoft Academic Search

The structure and composition evolution of polyvinyl alcohol (PVA) fibers during the fabrication of activated carbon fibers (ACF) by a newly developed method were systematically elucidated. The pore structure of the fibers was significantly influenced by the carbonization and activation conditions. The elemental composition and chemical structure evolution of the fibers during the heat treatment processes were evaluated by elemental

Shu-Juan Zhang; Hui-Min Feng; Jian-Ping Wang; Han-Qing Yu

2008-01-01

201

Nitric acid vapor removal by activated, impregnated carbons  

SciTech Connect

Laboratory and industrial workers can be exposed to vapors of nitric acid, especially in accidents, such as spills. Nitric acid can also be a product of incineration for energy production or waste (e.g., CW agent) disposal. Activated carbons containing impregnants for enhancing vapor and gas removal have been tested for effectiveness in removing vapors of nitric acid from air. The nitric acid vapor was generated from concentrated acid solutions and detected by trapping in a water bubbler for pH measurements. Both low and moderate relative humidity conditions were used. All carbons were effective at vapor contact times representative of air-purifying respirator use. One surprising observation was the desorption of low levels of ammonia from impregnated carbons. This was apparently due to residual ammonia from the impregnation processes.

Wood, G.O.

1996-12-31

202

Void forming pyrolytic carbon coating process  

SciTech Connect

A pyrolytic carbon coated nuclear fuel particle and method of making it are disclosed. The fuel particle has a core composed of a refractory compound of an actinide metal. The pyrolytic carbon coating surrounds the core so as to provide a void volume therebetween. The coating has an initial density of no greater than 1.45 grams/cm{sup 3} and an anisotropy factor than 3.0 and a final density upon heat treatment above about 2,000 C of greater than 1.7 grams/cm{sup 3} and an anisotropy factor greater than 5.

Beatty, R.L.; Cook, J.L.

2000-06-27

203

Void forming pyrolytic carbon coating process  

DOEpatents

A pyrolytic carbon coated nuclear fuel particle and method of making it. The fuel particle has a core composed of a refractory compound of an actinide metal. The pyrolytic carbon coating surrounds the core so as to provide a void volume therebetween. The coating has an initial density of no greater than 1.45 grams/cm.sup.3 and an anisotropy factor than 3.0 and a final density upon heat treatment above about 2000.degree. C. of greater than 1.7 grams/cm.sup.3 and an anisotropy factor greater than 5.

Beatty, Ronald L. (Oak Ridge, TN); Cook, Jackie L. (Oak Ridge, TN)

2000-01-01

204

Synthesis of a high-yield activated carbon by air gasification of macadamia nut shell charcoal  

Microsoft Academic Search

Macadamia nut shell charcoal was heated in an inert environment to temperatures above 1000 K (carbonized), reacted with oxygen (Poâ = 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

Xiangfeng Dai; Michael Jerry Antal

1999-01-01

205

Activation of structural carbon fibres for potential applications in multifunctional structural supercapacitors.  

PubMed

The feasibility of modifying conventional structural carbon fibres via activation has been studied to create fibres, which can be used simultaneously as electrode and reinforcement in structural composite supercapacitors. Both physical and chemical activation, including using steam, carbon dioxide, acid and potassium hydroxide, were conducted and the resulting fibre properties compared. It was proven that the chemical activation using potassium hydroxide is an effective method to prepare activated structural carbon fibres that possess both good electrochemical and mechanical properties. The optimal activation conditions, such as the loading of activating agent and the burn-off of carbon fibres, was identified and delivered a 100-fold increase in specific surface area and 50-fold improvement in specific electrochemical capacitance without any degradation of the fibre mechanical properties. The activation process was successfully scaled-up, showing good uniformity and reproducibility. These activated structural carbon fibres are promising candidates as reinforcement/electrodes for multifunctional structural energy storage devices. PMID:23312580

Qian, Hui; Diao, Hele; Shirshova, Natasha; Greenhalgh, Emile S; Steinke, Joachim G H; Shaffer, Milo S P; Bismarck, Alexander

2012-12-19

206

Acid sorption regeneration process using carbon dioxide  

US Patent & Trademark Office Database

Carboxylic acids are sorbed from aqueous feedstocks onto a solid adsorbent in the presence of carbon dioxide under pressure. The acids are freed from the sorbent phase by a suitable regeneration method, one of which is treating them with an organic alkylamine solution thus forming an alkylamine-carboxylic acid complex which thermally decomposes to the desired carboxylic acid and the alkylamine.

2001-11-13

207

Material Processing with Hydrogen and Carbon Monoxide on MARS.  

National Technical Information Service (NTIS)

Several novel proposals are examined for propellant production from carbon dioxide and monoxide and hydrogen. Potential uses were also examined of CO as a fuel or as a reducing agent in metal oxide processing as obtained or further reduced to carbon. Hydr...

A. F. Hepp G. A. Landis D. L. Linne

1991-01-01

208

Entrainment process of carbon dioxide in the atmospheric boundary layer  

Microsoft Academic Search

Aircraft and surface measurements of turbulent thermodynamic variables and carbon dioxide (CO2) were taken above a grassland in a convective atmospheric boundary layer. The observations were analyzed to assess the importance of the entrainment process for the distribution and evolution of carbon dioxide in the boundary layer. From the observations we were able to estimate the vertical profiles of the

Jordi Vilà-Guerau de Arellano; Beniamino Gioli; Franco Miglietta; Harm J. J. Jonker; Henk Klein Baltink; Ronald W. A. Hutjes; Albert A. M. Holtslag

2004-01-01

209

Processing and applications of carbon based nano-materials  

Microsoft Academic Search

Carbon-based nanomaterials, including single walled carbon nanotubes (SWNTs) and graphite nanoplatelets (GNPs, multi-layer graphene), possess exceptional electrical, thermal and mechanical properties coupled with high aspect ratio and high temperature stability. These unique properties have attracted increased attention during the past decade. These materials form the basis of the work presented here, which includes research targeting fabrication, processing and applications in

Aiping Yu

2008-01-01

210

Preparing and characterizing the active carbon produced by steam and carbon dioxide as a heavy oil hydrocracking catalyst support  

Microsoft Academic Search

Active carbon was prepared from Yallourn brown coal char using steam and carbon dioxide activation in a laboratory rotary kiln. The activation rate with steam was faster than that with carbon dioxide. The pore structure of the active carbons was characterized using the nitrogen isotherms at 77K. The pore volume and specific surface area of the active carbon increased with

Hidetsugu Fukuyama; Satoshi Terai

2008-01-01

211

Carbon dioxide sequestration by direct mineral carbonation: process mineralogy of feed and products  

SciTech Connect

Direct mineral carbonation has been investigated as a process to convert gaseous CO2 into a geologically stable final form. The process utilizes a slurry of water, with bicarbonate and salt additions, mixed with a mineral reactant, such as olivine (Mg2SiO4) or serpentine [Mg3Si2O5(OH)4]. Carbon dioxide is dissolved into this slurry, resulting in dissolution of the mineral and precipitation of magnesium carbonate (MgCO3). Optimum results have been achieved using heat pretreated serpentine feed material and high partial pressure of CO2 (PCO2). Specific conditions include: 155?C; PCO2=185 atm; 15% solids. Under these conditions, 78% conversion of the silicate to the carbonate was achieved in 30 minutes. Process mineralogy has been utilized to characterize the feed and process products, and interpret the mineral dissolution and carbonate precipitation reaction paths.

O'Connor, William K.; Dahlin, David C.; Rush, G.E.; Dahlin, Cheryl L.; Collins, W. Keith

2001-01-01

212

Authigenic carbonates from active methane seeps offshore southwest Africa  

NASA Astrophysics Data System (ADS)

The southwest African continental margin is well known for occurrences of active methane-rich fluid seeps associated with seafloor pockmarks at water depths ranging broadly from the shelf to the deep basins, as well as with high gas flares in the water column, gas hydrate accumulations, diagenetic carbonate crusts and highly diverse benthic faunal communities. During the M76/3a expedition of R/V METEOR in 2008, gravity cores recovered abundant authigenic carbonate concretions from three known pockmark sites—Hydrate Hole, Worm Hole, the Regab pockmark—and two sites newly discovered during that cruise, the so-called Deep Hole and Baboon Cluster. The carbonate concretions were commonly associated with seep-benthic macrofauna and occurred within sediments bearing shallow gas hydrates. This study presents selected results from a comprehensive analysis of the mineralogy and isotope geochemistry of diagenetic carbonates sampled at these five pockmark sites. The oxygen isotope stratigraphy obtained from three cores of 2-5 m length indicates a maximum age of about 60,000-80,000 years for these sediments. The authigenic carbonates comprise mostly magnesian calcite and aragonite, associated occasionally with dolomite. Their very low carbon isotopic compositions (-61.0 < ?13C ‰ V-PDB < -40.1) suggest anaerobic oxidation of methane (AOM) as the main process controlling carbonate precipitation. The oxygen isotopic signatures (+2.4 < ?18O ‰ V-PDB < +6.2) lie within the range in equilibrium under present-day/interglacial to glacial conditions of bottom seawater; alternatively, the most positive ?18O values might reflect the contribution of 18O-rich water from gas hydrate decomposition. The frequent occurrence of diagenetic gypsum crystals suggests that reduced sulphur (hydrogen sulphide, pyrite) from sub-seafloor sediments has been oxidized by oxygenated bottom water. The acidity released during this process can potentially induce the dissolution of carbonate, thereby providing enough Ca2+ ions for pore solutions to reach gypsum saturation; this is thought to be promoted by the bio-irrigation and burrowing activity of benthic fauna. The ?18O-?13C patterns identified in the authigenic carbonates are interpreted to reflect variations in the rate of AOM during the last glacial-interglacial cycle, in turn controlled by variably strong methane fluxes through the pockmarks. These results complement the conclusions of Kasten et al. in this special issue, based on authigenic barite trends at the Hydrate Hole and Worm Hole pockmarks which were interpreted to reflect spatiotemporal variations in AOM related to subsurface gas hydrate formation-decomposition.

Pierre, Catherine; Blanc-Valleron, Marie-Madeleine; Demange, Jérôme; Boudouma, Omar; Foucher, Jean-Paul; Pape, Thomas; Himmler, Tobias; Fekete, Noemi; Spiess, Volkhard

2012-12-01

213

Processing of Activated Core Components  

SciTech Connect

Used activated components from the core of a NPP like control elements, water channels from a BWR, and others like in-core measurement devices need to be processed into waste forms suitable for interim storage, and for the final waste repository. Processing of the activated materials can be undertaken by underwater cutting and packaging or by cutting and high-pressure compaction in a hot cell. A hot cell is available in Germany as a joint investment between GNS and the Karlsruhe Research Center at the latter's site. Special transport equipment is available to transport the components ''as-is'' to the hot cell. Newly designed underwater processing equipment has been designed, constructed, and operated for the special application of NPP decommissioning. This equipment integrates an underwater cutting device with an 80 ton force underwater in-drum compactor.

Friske, A.; Gestermann, G.; Finkbeiner, R.

2003-02-26

214

Lost carbonate sintering process for manufacturing metal foams  

Microsoft Academic Search

This article describes a lost carbonate sintering process for manufacturing open cell metal foams. Cu foams with porosity in the range 50–85% and cell sizes in the range 53–1500?m have been manufactured.

Y. Y. Zhao; T. Fung; L. P. Zhang; F. L. Zhang

2005-01-01

215

Investigation kinetics mechanisms of adsorption malachite green onto activated carbon  

Microsoft Academic Search

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 1000m2\\/g. Adsorption capacity of malachite green (MG) onto T3K618 activated

Y. Önal; C. Akmil-Ba?ar; Ç. Sar?c?-Özdemir

2007-01-01

216

Processing carbon nanotubes with holographic optical tweezers  

Microsoft Academic Search

We report the first demonstration that carbon nanotubes can be trapped and\\u000amanipulated by optical tweezers. This observation is surprising because\\u000aindividual nanotubes are substantially smaller than the wavelength of light,\\u000aand thus should not be amenable to optical trapping. Even so, nanotube bundles,\\u000aand perhaps even individual nanotubes, can be transported at high speeds,\\u000adeposited onto substrates, untangled, and

Joseph Plewa; Evan Tanner; Daniel M. Mueth; David G. Grier

2004-01-01

217

Process synthesis and optimization for the production of carbon nanostructures  

NASA Astrophysics Data System (ADS)

A swirled fluidized bed chemical vapour deposition (SFCVD) reactor has been manufactured and optimized to produce carbon nanostructures on a continuous basis using in situ formation of floating catalyst particles by thermal decomposition of organometallic ferrocene. During the process optimization, carbon nanoballs were produced in the absence of a catalyst at temperatures higher than 1000 °C, while carbon nanofibres, single-walled carbon nanotubes, helical carbon nanotubes, multi-walled carbon nanotubes (MWCNTs) and carbon nanofibres (CNFs) were produced in the presence of a catalyst at lower temperatures of between 750 and 900 °C. The optimum conditions for producing carbon nanostructures were a temperature of 850 °C, acetylene flow rate of 100 ml min-1, and acetylene gas was used as the carbon source. All carbon nanostructures produced have morphologies and diameters ranging from 15 to 200 nm and wall thicknesses between 0.5 and 0.8 nm. In comparison to the quantity of MWCNTs produced with other methods described in the literature, the SFCVD technique was superior to floating catalytic CVD (horizontal fixed bed) and microwave CVD but inferior to rotary tube CVD.

Iyuke, S. E.; Mamvura, T. A.; Liu, K.; Sibanda, V.; Meyyappan, M.; Varadan, V. K.

2009-09-01

218

Carbon Limited Heterotrophic Activity in an Urban Stream  

NASA Astrophysics Data System (ADS)

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

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

2005-05-01

219

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...

220

The regeneration of polluted activated carbon by radiation techniques  

NASA Astrophysics Data System (ADS)

In this paper, the regeneration of used activated carbon from monosodium glutamate factory was experimented using radiation and acid-alkali chemical cleaning method. Results showed that the activated carbon saturated with pollutants can be wash away easily by flushing with chemical solution prior irradiation. DSC was used to monitor the change of carbon adsorption

Minghong, W.; Borong, B.; Ruimin, Z.; Jinliang, Z.; Longxin, H.

1998-10-01

221

BACTERIA ASSOCIATED WITH GRANULAR ACTIVATED CARBON PARTICLES IN DRINKING WATER  

EPA Science Inventory

A sampling protocol was developed to examine particles released from granular activated carbon filter beds. A gauze filter/Swinnex procedure was used to collect carbon fines from 201 granular activated carbon-treated drinking water samples over 12 months. Application of a homogen...

222

Histochemical demonstration of carbonic anhydrase activity  

Microsoft Academic Search

Freeze-dried frozen sections are floated on the surface of the freshly prepared incubation mixture (CoSO4 1.75 × 10-3M, H2SO4 5.3 × 10-2M, NaHCO3 1.57 × 10-2M and KH2PO4 1.17 to 11.7 × 10-3M; demonstration of weak activity requires high phosphate). A compound containing cobalt and phosphorous precipitates at carbonic anhydrase sites and is converted to CoS. Adequate staining requires only

Holger P. J. Hansson

1967-01-01

223

Applicability of Activated Carbon to Treatment of Waste Containing Iodine-Labeled Compounds  

Microsoft Academic Search

A timber industry waste was transformed to activated carbon by a one-step chemical activation process using H3PO4 (H). The used activated carbon (SDH) was characterized by N2 adsorption, FTIR, density, pH, point of zero charge pHpzc, moisture and ash content. Methylene blue (MB) and the iodine number were calculated by adsorption from the solution. The applicability of the different activated

H. M. H. Gad; N. R. A. El-Mouhty; H. F. Aly

2009-01-01

224

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

NASA Astrophysics Data System (ADS)

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.

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

2013-09-01

225

Effect of natural organic matter loading on the atrazine adsorption capacity of an aging powdered activated carbon slurry  

Microsoft Academic Search

The effect of natural organic matter loading and calcium carbonate precipitate towards atrazine adsorption capacity of an aging powdered activated carbon slurry was investigated in an hybrid membrane process consisting of an immersed microfiltration membrane system in a completely stirred tank reactor containing powdered activated carbon. The reactor was fed with clarified Seine river water containing natural organic matter (NOM).

T Lebeau; C Lelièvre; D Wolbert; A Laplanche; M Prados; P Côté

1999-01-01

226

DISINFECTION OF BACTERIA ATTACHED TO GRANULAR ACTIVATED CARBON  

EPA Science Inventory

Heterotrophic plate count bacteria, coliform organisms, and pathogenic microorganisms attached to granular activated carbon (GAC) particles were examined for their susceptibility to chlorine disinfection. When these bacteria were grown on carbon particles and then disinfected wit...

227

SIMS/XPS investigations on activated carbon catalyst supports  

SciTech Connect

The surface modifications of activated carbon catalyst supports due to HCl treatment were measured in investigations combining X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometry (SIMS). The surface properties of carbons derived from beech wood, pine wood, and bitumen were qualitatively characterized by analyzing selected positively and negatively charged fragment ions in SIMS experiments. Surface modification and lot-to-lot variations were found with respect to surface oxygen, aliphatic and aromatic/graphite carbon, and surface C/H ratios. The surface characteristics of the supports correlated partly with properties of catalytic interest such as the valency and dispersion of precious metals which were deposited on these supports. The interaction between the activated carbon surfaces and precious metal compounds is apparently governed not only by the redox behavior of C/O and heterofunctional groups but also by the concentration of surface hydrogen. The surface hydrogen seems to enhance redox processes in the precious metal impregnation step of catalyst preparation. Therefore, surface hydrogen is an important parameter for controlling catalyst properties in catalyst preparation and should be carefully monitored. 32 refs., 4 figs., 5 tabs.

Albers, P.; Deller, K.; Despeyroux, B.M.; Prescher, G.; Shaefer, A.; Seibold, K. [Degussa AG, Hanau (Germany)

1994-12-01

228

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

Microsoft Academic Search

Mercury has had various uses in nuclear fuel reprocessing and other nuclear processes, and so is often present in radioactive and mixed (radioactive and hazardous) wastes. Test programs performed in recent years have shown that mercury in off-gas streams from processes that treat radioactive wastes can be controlled using fixed beds of activated sulfur-impregnated carbon, to levels low enough to

Nick Soelberg; Joe Enneking

2011-01-01

229

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

National Technical Information Service (NTIS)

The method of supercritical carbon dioxide (SCF CO2) regeneration of granular activated carbon (GAC) loaded with DIMP (diisopropyl methylphosphonate) from Rocky Mountain Arsenal Well (NO. 23-120) water was investigated. A laboratory-based adsorption/regen...

R. M. O'Brien R. P. de Filippi C. E. Smith D. G. Hager

1982-01-01

230

In situ activation of carbon fiber microdisk electrodes  

NASA Astrophysics Data System (ADS)

Carbon fiber microdisk electrodes (11 micron in diameter) were activated in situ via intense laser pulses produced by a small nitrogen laser. The laser beam was focussed down to a small spot size to ensure adequate power density. The laser treatment resulted in more Nernstian voltammetry for dopamine, 4-methylcatechol, and 3, 4-dihydroxyphenylacetate in several different buffer systems over a range of pH. The effect of buffer composition and pH on the apparent electrode kinetics observed both before and after laser treatment was studied. An apparent cleaning of the electrode surface by the laser pulses results in more Nernstian voltammetry; however, voltammograms obtained in some buffer systems, particularly those containing citrate, show anomalous effects after laser treatment. A model of the activation process is presented which might explain the observed phenomenon by surface ablation exposing clean, active carbon, followed by adsorption of solution species. This activation procedure is presented as a simple, fairly inexpensive way to obtain consistent, repetitive voltammetry at carbon fiber microdisk electrodes.

Strein, Timothy G.; Ewing, Andrew G.

1990-11-01

231

Correlation between Carbonic Anhydrase Activity and Inorganic Carbon Internal Pool in Strain Synechocystis PCC 6174.  

PubMed

Existence of an internal carbonic anhydrase was demonstrated in the cyanobacterium Synechocystis PCC 6714. The enzyme, present at a low specific activity, was inducible by limitation in inorganic carbon and inhibited both in vivo and in vitro by acetazolamide. The internal inorganic carbon pool as determined by mass spectrometry, was similarly modulated by the actual inorganic carbon growth regime; its building up was also sensitive to acetazolamide. A possible role of carbonic anhydrase in inorganic carbon metabolism regulation through the control of the dimension and nature of the inorganic carbon pool is discussed. PMID:16666795

Bédu, S; Peltier, G; Joset, F

1989-06-01

232

Correlation between Carbonic Anhydrase Activity and Inorganic Carbon Internal Pool in Strain Synechocystis PCC 6174 1  

PubMed Central

Existence of an internal carbonic anhydrase was demonstrated in the cyanobacterium Synechocystis PCC 6714. The enzyme, present at a low specific activity, was inducible by limitation in inorganic carbon and inhibited both in vivo and in vitro by acetazolamide. The internal inorganic carbon pool as determined by mass spectrometry, was similarly modulated by the actual inorganic carbon growth regime; its building up was also sensitive to acetazolamide. A possible role of carbonic anhydrase in inorganic carbon metabolism regulation through the control of the dimension and nature of the inorganic carbon pool is discussed.

Bedu, Sylvie; Peltier, Gilles; Joset, Francoise

1989-01-01

233

Role of activated carbon pellets in carbon dioxide removal  

Microsoft Academic Search

The removal of carbon dioxide from gas\\/air streams is more often becoming necessary in many industries for different purposes. In cryogenic air separation plant, air has to be free from carbon dioxide before its liquefaction otherwise blockage due to freezing of heat exchange equipment would result. Enrichment of methane in biogas to have fuel of higher calorific value can be

S. C Sarkar; A Bose

1997-01-01

234

Micro-scale investigation of carbonation process in partially serpentinized peridotites  

NASA Astrophysics Data System (ADS)

The carbonation of ultramafic rocks is, theoretically, the most efficient reaction to trap CO2 irreversibly in the form of solid carbonates, as predicted by equilibrium thermodynamic calculations. However, the success of industrial or natural carbonation in large ultramafic aquifers or oceanic ultramafic exposures does not only rely on the thermodynamic conditions of chemical reactions, but also on their feedback effects on the reactive surface area and on the local porosity and permeability. In addition, side processes like serpentinization, redox reactions, abiotic catalytic effects, and biological activity, can be expected in such complex natural system. Their occurrence and implications on carbon speciation and carbon transfers during hydrothermal alteration of oceanic peridotites have not been explored yet and requires detailed study of natural and/or experimental carbonation zones. We have combined petrographic and electron microscopy with SIMS, Raman and FTIR microspectroscopy on partially serpentinized peridotites drilled during the IODP leg 304 (30°N, MAR) in order to characterize the mechanisms of peridotite carbonation at the fluid-mineral interface and identify the associated speciation of carbon (inorganic and organic carbon occurrences). We present first results on zones located close to talc-tremolite sheared veins in holes 1309B and D. Associations of carbonates, porous phyllosilicates and oxides are observed in close vicinity of relict olivines that underwent a previous stage of serpentinization. The olivine-carbonate interface is nanoporous which facilitates mass transfer between fluid and mineral. The phyllosilicate identified as saponite results from the metasomatic replacement, during the carbonation stage, of previously formed serpentine. These observations do not favour reaction-induced cracking but rather a transfer-controlled process in an open system. Among the submicrometric dark clusters widely-distributed in saponite and in serpentine, vibrational microspectroscopy reveals the presence of various types of organic compounds that tend to be located close to micrometric sulphides grains. Those results underline the microscale variability of carbon speciation within hydrothermally altered peridotites. The association of reduced carbon phases with the carbonation texture suggests that CO2 conversion may not be limited to solid carbonate formation in natural systems and that biological activity and/or abiotic CO2 reduction, possibly catalyzed by Ni-rich sulphides, can occur contemporaneously. This complex association of reactions has to be unravelled further to determine the respective contribution of abiotic versus biological processes and integrate them in carbon transfers modelling through the oceanic lithosphere.

Andreani, M.; Menez, B.; Delacour, A.; Pasini, V.; Auzende, A. L.; Brunelli, D.

2012-04-01

235

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

PubMed

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. PMID:11111338

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

2000-11-01

236

Quality of poultry litter-derived granular activated carbon  

Microsoft Academic Search

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

Guannan Qiu; Mingxin Guo

2010-01-01

237

Sodium to sodium carbonate conversion process  

DOEpatents

A method is described for converting radioactive alkali metal into a low level disposable solid waste material. The radioactive alkali metal is atomized and introduced into an aqueous caustic solution having caustic present in the range of from about 20 wt % to about 70 wt % to convert the radioactive alkali metal to a radioactive alkali metal hydroxide. The aqueous caustic containing radioactive alkali metal hydroxide and CO{sub 2} are introduced into a thin film evaporator with the CO{sub 2} present in an amount greater than required to convert the alkali metal hydroxide to a radioactive alkali metal carbonate, and thereafter the radioactive alkali metal carbonate is separated from the thin film evaporator as a dry powder. Hydroxide solutions containing toxic metal hydroxide including one or more metal ions of Sb, As, Ba, Be, Cd, Cr, Pb, Hg, Ni, Se, Ag and Tl can be converted into a low level non-hazardous waste using the thin film evaporator of the invention. 3 figs.

Herrmann, S.D.

1997-10-14

238

Sodium to sodium carbonate conversion process  

DOEpatents

A method of converting radioactive alkali metal into a low level disposable solid waste material. The radioactive alkali metal is atomized and introduced into an aqueous caustic solution having caustic present in the range of from about 20 wt % to about 70 wt % to convert the radioactive alkali metal to a radioactive alkali metal hydroxide. The aqueous caustic containing radioactive alkali metal hydroxide and CO.sub.2 are introduced into a thin film evaporator with the CO.sub.2 present in an amount greater than required to convert the alkali metal hydroxide to a radioactive alkali metal carbonate, and thereafter the radioactive alkali metal carbonate is separated from the thin film evaporator as a dry powder. Hydroxide solutions containing toxic metal hydroxide including one or more metal ions of Sb, As, Ba, Be, Cd, Cr, Pb, Hg, Ni, Se, Ag and T1 can be converted into a low level non-hazardous waste using the thin film evaporator of the invention.

Herrmann, Steven D. (Idaho Falls, ID)

1997-01-01

239

REACTIONS OF CHLORITE WITH ACTIVATED CARBON AND WITH VANILLIC ACID AND INDAN ADSORBED ON ACTIVATED CARBON  

EPA Science Inventory

The reaction between chlorite (CO2(-1)) and vanillic acid, at pH 6.0 in the presence of granular activated carbon (GAC), yielded several reaction products identifiable by GC/MS; no products were found in the absence of GAC. Indan and ClO2 or ClO2(-1) reacted in aqueous solution a...

240

Use of an activated carbon from antibiotic waste for the removal of Hg(II) from aqueous solution  

Microsoft Academic Search

Porous carbon has been prepared from waste antibiotic material by a chemical activation method using K2CO3 as an activating reagent. Carbon was studied systematically by the adsorption of nitrogen and iodine. It was found that the process parameters such as activation temperature and activation time are crucial for preparing high-quality activated carbon. The proper choice of the preparation conditions allows

Temenuzhka Budinova; Nartzislav Petrov; Jose Parra; Venelin Baloutzov

2008-01-01

241

Hydrogen production by thermo-catalytic decomposition of methane: Regeneration of active carbons using CO 2  

Microsoft Academic Search

Thermo-catalytic decomposition of methane using carbons as catalyst is a very attractive process for free CO2–hydrogen production. One of the main drawbacks for the sustainability of the process is catalyst deactivation. In this work, regeneration of a deactivated active-carbon catalyst has been studied using CO2 as activating agent under different regeneration conditions. It has been stated that during the regeneration

J. L. Pinilla; I. Suelves; R. Utrilla; M. E. Gálvez; M. J. Lázaro; R. Moliner

2007-01-01

242

Superhydrophobic activated carbon-coated sponges for separation and absorption.  

PubMed

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. PMID:23650204

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

2013-05-03

243

Independently Controlled Carbon and Nitrogen Potential: A New Approach to Carbonitriding Process  

NASA Astrophysics Data System (ADS)

Recent research projects show that retained austenite, if stabilized by nitrogen, has a positive influence on the fatigue strength of work pieces. The combined diffusion profile of carbon and nitrogen applied in a carbonitriding process plays a major role, besides the process temperature. Yet today, only the carbon potential is somehow controlled and even this is not easy to achieve. This paper will present a new system able to measure and control both the carbon potential and the nitrogen potential independently. The knowledge of the activities of nitrogen and carbon in iron and the effect of alloying elements on such activities as well as the solubilities offers a way to apply the potentials on real steels.

Winter, Karl-Michael

2013-04-01

244

Nitrification enhancement by powdered activated carbon addition in activated sludge  

SciTech Connect

Previous investigators provided evidence that the addition of powdered activated carbon (PAC) to nitrifying activated sludge (AS) can improve nitrification rates. Plausible but unsubstantiated mechanisms proposed to explain these observations include adsorption of compounds toxic to nitrifiers; enhanced growth of nitrifiers and/or concentration of trace nutrients on the carbon surface. The major objective of this research is to further define the mechanics of nitrification enhancement in PAC-AS. Using refinery and synthetic wastewater feed, a series of acute and chronic experiments, as well as experiments with variable carbon dosages, was conducted to evaluate the relative importance of adsorption, suspended solids, and microbial acclimation on AS nitrification rates. The general procedure was to compare the effect of a spiked adsorbable/non-adsorbable, inhibitory compound on nitrification rates in AS and in AS supplemented either with PAC or inert suspended solids (bentonite clay). With spiked adsorbable inhibitors, the acute experiments demonstrated nitrification enhancement due to PAC addition in unacclimated sludge cultures. Statistically significant enhancement due to either PAC or bentonite addition was not evident in any experiment where a nonadsorbable inhibitor was added. A chronic experiment gave evidence that the addition of PAC of AS can inhibit nitrification by virtue of desorption of a previously adsorbed inhibitor. In this same experiment, it was shown that an adequate dose of virgin PAC can dramatically arrest the effect of an adsorbable inhibitor and restore full nitrification capability.

Ng, A.S.

1985-01-01

245

Adsorption of dyes onto activated carbon prepared from olive stones.  

PubMed

Activated carbon was produced from olive stones(OSAC) by a physical process in two steps. The adsorption character of this activated carbon was tested on three colour dyes molecules in aqueous solution: Methylene blue (MB), Rhodamine B (RB) and Congo Red(CR). The adsorption equilibrium was studied through isotherms construction at 30 degrees C, which were well described by Langmuir model. The adsorption capacity on the OSAC was estimated to be 303 mg/g, 217 mg/g and 167 mg/g respectively for MB, RB and CR. This activated carbon has a similar adsorption properties to that of commercial ones and show the same adsorption performances. The adsorption kinetics of the MB molecule in aqueous solution at different initial concentrations by OSAC was also studied. Kinetic experiments were well fitted by a simple intra-particle diffusion model. The measured kinetics constant was influenced by the initial concentration and we found the following correlation: Kid = 1.55 C0(0.51). PMID:16465895

Najar-Souissi, Souad; Ouederni, Abdelmottaleb; Ratel, Abdelhamid

2005-01-01

246

Restricted dynamics of molecular hydrogen confined in activated carbon nanopores  

SciTech Connect

Quasi-elastic neutron scattering was used for characterization of dynamics of molecular hydrogen confined in narrow nanopores of two activated carbon materials: PFAC (derived from polyfurfuryl alcohol) and UMC (ultramicroporous carbon). Fast, but incomplete ortho-para conversion was observed at 10 K, suggesting that scattering originates from the fraction of unconverted ortho isomer which is rotation-hindered because of confinement in nanopores. Hydrogen molecules entrapped in narrow nanopores (<7 ) were immobile below 22-25 K. Mobility increased rapidly with temperature above this threshold, which is 8 K higher than the melting point of bulk hydrogen. Diffusion obeyed fixed-jump length mechanism, indistinguishable between 2D and 3D processes. Thermal activation of diffusion was characterized between ~22 and 37 K, and structure-dependent differences were found between the two carbons. Activation energy of diffusion was higher than that of bulk solid hydrogen. Classical notions of liquid and solid do not longer apply for H2 confined in narrow nanopores.

Contescu, Cristian I [ORNL; Saha, Dipendu [ORNL; Gallego, Nidia C [ORNL; Mamontov, Eugene [ORNL; Kolesnikov, Alexander I [ORNL; Bhat, Vinay V [ORNL

2012-01-01

247

Innovative Technology of COD and BOD Reduction from Coffee Processing Wastewater Using Avocado Seed Carbon (ASC)  

Microsoft Academic Search

The study estimated the efficiency of Avocado seed carbon (ASC) for chemical oxygen demand (COD) and biochemical oxygen demand\\u000a (BOD) reduction from coffee processing wastewater. It was performed under batch mode conditions to investigate the optimum\\u000a operating conditions and efficiency for COD and BOD reduction with ASC compared with commercial activated carbon (CAC). Adsorption\\u000a isotherm study was also performed and

Rani Devi

2010-01-01

248

Low Speed Carbon Deposition Process for Hermetic Optical Fibers  

SciTech Connect

For optical fibers used in adverse environments, a carbon coating is frequently deposited on the fiber surface to prevent water and hydrogen ingression that lead respectively to strength degradation through fatigue and hydrogen-induced attenuation. The deposition of a hermetic carbon coating onto an optical fiber during the draw process holds a particular challenge when thermally-cured specialty coatings are subsequently applied because of the slower drawing rate. In this paper, we report on our efforts to improve the low-speed carbon deposition process by altering the composition and concentration of hydrocarbon precursor gases. The resulting carbon layers have been analyzed for electrical resistance, Raman spectra, coating thickness, and surface roughness, then compared to strength data and dynamic fatigue behavior.

ABRAMCZYK,JAROSLAW; ARTHUR,SARA E. TALLANT,DAVID R.; HIKANSSON,ADAM S.; LINDHOLM,ERIC A.; LO,JIE

1999-09-29

249

Nitrogen and carbon oxides chemistry in the HRS retorting process  

Microsoft Academic Search

The HRS Oil Shale Retort process consists of a pyrolysis section which converts kerogen of the shale to liquid and gaseous products, and a combustion section which burns residual carbon on the shale to heat the process. Average gas concentrations of selected gas phase species were determined from data measured at several placed on the combustion system of the Lawrence

1993-01-01

250

Evaluation of Current Process Technology in Coal Carbonization and Hydrocarbonization.  

National Technical Information Service (NTIS)

It has been shown that a number of processes for carbonization and hydrocarbonization of bituminous coals are available but only one, the Lurgi-Ruhrgas process, has been developed to a commercial stage at the present time. The others are in various stages...

D. S. Joy H. D. Cochran J. M. Holmes M. S. Edwards P. M. Lantz

1975-01-01

251

Removal of carbonyl sulfide using activated carbon adsorption.  

PubMed

Wastewater treatment plant odors are caused by compounds such as hydrogen sulfide (H2S), methyl mercaptans, and carbonyl sulfide (COS). One of the most efficient odor control processes is activated carbon adsorption; however, very few studies have been conducted on COS adsorption. COS is not only an odor causing compound but is also listed in the Clean Air Act as a hazardous air pollutant. Objectives of this study were to determine the following: (1) the adsorption capacity of 3 different carbons for COS removal; (2) the impact of relative humidity (RH) on COS adsorption; (3) the extent of competitive adsorption of COS in the presence of H2S; and (4) whether ammonia injection would increase COS adsorption capacity. Vapor phase react (VPR; reactivated), BPL (bituminous coal-based), and Centaur (physically modified to enhance H2S adsorption) carbons manufactured by Calgon Carbon Corp. were tested in three laboratory-scale columns, 6 in. in depth and 1 in. in diameter. Inlet COS concentrations varied from 35 to 49 ppmv (86-120 mg/m3). RHs of 17%, 30%, 50%, and 90% were tested. For competitive adsorption studies, H2S was tested at 60 ppmv, with COS at 30 ppmv. COS, RH, H2S, and ammonia concentrations were measured using an International Sensor Technology Model IQ-350 solid state sensor, Cole-Parmer humidity stick, Interscan Corp. 1000 series portable analyzer, and Drager Accuro ammonia sensor, respectively. It was found that the adsorption capacity of Centaur carbon for COS was higher than the other two carbons, regardless of RH. As humidity increased, the percentage of decrease in adsorption capacity of Centaur carbon, however, was greater than the other two carbons. The carbon adsorption capacity for COS decreased in proportion to the percentage of H2S in the gas stream. More adsorption sites appear to be available to H2S, a smaller molecule. Ammonia, which has been found to increase H2S adsorption capacity, did not increase the capacity for COS. PMID:16568805

Sattler, Melanie L; Rosenberk, Ranjith Samuel

2006-02-01

252

Removal of bromide and iodide anions from drinking water by silver-activated carbon aerogels  

Microsoft Academic Search

The aim of this study is to analyze the use of Ag-doped activated carbon aerogels for bromide and iodide removal from drinking water and to study how the activation of Ag-doped aerogels affects their behavior. It has been observed that the carbonization treatment and activation process of Ag-doped aerogels increased the surface area value (SN2), whereas the volume of meso-(V2)

M. Sánchez-Polo; J. Rivera-Utrilla; E. Salhi; U. von Gunten

2006-01-01

253

Electrolytic treatment of mercury-loaded activated carbon from a gas cleaning system  

PubMed

This study aimed at extracting the adsorbed mercury from the mercury-loaded activated carbon so as to recycling both, the elemental mercury and the carbon, after being reactivated. The process used in this study was the electro-oxidation of the mercury in a reaction system where the loaded carbon is acting as an anode, during the electrolysis of brine, the electrolyte of the cell. PMID:11036991

Sobral; Santos; Barbosa

2000-10-16

254

Carbon nanotube-reinforced composites: Processing, characterization and modeling  

Microsoft Academic Search

The exceptionally high specific stiffness and strengths reported for carbon nanotubes, combined with their fiber-like structure, has stimulated research in the development of polymer nanocomposites reinforced with carbon nanotubes. Before these extraordinary properties observed at the nano-scale are realized in a macroscopic composite, considerable basic research is necessary. This research work seeks to obtain a fundamental understanding of the processing\\/structure\\/property

Erik T. Thostenson

2003-01-01

255

Processing and properties of silicon-carbon liquid encapsulants  

Microsoft Academic Search

In 1992, SYCAR resin, a new silicon-carbon thermosetting resin, was introduced to the electronics industry. Characteristics of the resin include excellent moisture resistance, ionic purity, low dielectric constant, and good-thermal properties. This combination of properties makes the resin particularly suited for encapsulant applications. In this paper, the processing and properties of silicon-carbon liquid encapsulants are presented in detail. Production of

J. K. Bard; R. L. Brady; J. M. Schwark

1993-01-01

256

Kinetics and isotherm studies on electrosorption of NaCl by activated carbon fiber, carbon nanotube and carbon nanotube-carbon nanofiber composite films  

Microsoft Academic Search

In this paper, the structures of commercial activated carbon fiber (ACF), carbon nanotube (CNT) and home-made carbon nanotube-carbon nanofiber (CNT-CNF) films are characrerized and compare their electrochemical behaviors in NaCl solutions in order to study the electrosorption mechanism.

Yankun Zhan; Chunyang Nie; Haibo Li; Taiqiang Chen; Likun Pan; Zhuo Sun

2010-01-01

257

Preparation and characterization of mesoporous activated carbon from waste tires  

Microsoft Academic Search

Activated carbons were produced from waste tires and their characteristics were investigated. Rubber separated from waste tires was first carbonized at 500°C in N2 atmosphere. Next, the obtained chars were activated with steam at 850°C. As a result, fairly mesoporous activated carbons with mesopore volumes and BET surface areas up to 1.09 cm3\\/g and 737 m2\\/g, respectively, were obtained. To

P Ariyadejwanich; W Tanthapanichakoon; K Nakagawa; S. R Mukai; H Tamon

2003-01-01

258

Preparation of activated carbon from date pits: Effect of the activation agent and liquid phase oxidation  

Microsoft Academic Search

Two series of activated carbons have been prepared from date pits; series C, using carbon dioxide as activating agent, and series S, prepared by activation with steam under the same experimental conditions. The obtained samples were oxidized with nitric acid in order to introduce more oxygen surface groups. The surface area and porosity of the parent and oxidized activated carbons

Meriem Belhachemi; Rachel V. R. A. Rios; Fatima Addoun; Joaquín Silvestre-Albero; Antonio Sepúlveda-Escribano; Francisco Rodríguez-Reinoso

2009-01-01

259

Carbon black from coal by the HYDROCARB process  

SciTech Connect

The HYDROCARB process was conceived and developed for the purpose of producing a clean carbon fuel and coproduct gaseous and liquid fuel coproducts from any carbonaceous feedstock and particularly from coal. The process basically consists of two major steps. In the first step, coal is hydrogenated to produce methane. In this step, the carbonaceous raw material is gasified with a recycled hydrogen-rich gas stream to form a light hydrocarbon, methane-rich gas, while the non-volatile ash remains behind. With the optional addition of limestone to the feed material, sulfur in the feedstock is removed as non-volatile calcium sulfide which is later oxidized to calcium sulfate for disposal. The methane-rich gas which also contains carbon monoxide and smaller amounts of water and carbon dioxide is sent to a recuperative condenser. For the production of methanol, the carbon monoxide and hydrogen in the process gas is catalytically combined to produce methanol. The deoxygenated methane-rich gas stream is then sent to a methane decomposer where the methane is cracked to pure particulate carbon and hydrogen gas. The pure carbon is removed as a clan product and most of the hydrogen-rich gas is returned to the coal hydrogenator. The two basic steps are than coal hydrogasification in a hydropyrolysis reactor (HPR) and methane decomposition in a methane pyrolysis reactor (MPR). 6 refs., 3 figs., 2 tabs.

Steinberg, M.

1991-05-01

260

Production of charcoal and activated carbon at elevated pressure  

Microsoft Academic Search

With its wide range of properties, charcoal finds many commercial applications for domestic cooking, refining of metals (steel, copper, bronze, nickel, aluminum and electro-manganese), production of chemicals (carbon disulfide, calcium carbide, silicon carbide, sodium cyanide, carbon black, fireworks, gaseous chemicals, absorbents, soil conditioners and pharmaceuticals), as well as production of activated carbon and synthesis gas. In 1991, the world production

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

1995-01-01

261

Hydrogen Adsorption on Activated Carbon an Carbon Nanotubes Using Volumetric Differential Pressure Technique  

Microsoft Academic Search

A simple hydrogen adsorption measurement system utilizing the volumetri differential pressure technique has been designed, fabricated and calibrated. Hydroge adsorption measurements have been carried out at temperatures 298 K and 77 K on activate carbon and carbon nanotubes with different surface areas. The adsorption data obtained will b helpful in understanding the adsorption property of the studied carbon materials using

S. M. Sanip; M. A. R. Saidin; M. Aziz; A. F. Ismail

2010-01-01

262

Phenol adsorption by activated carbon produced from spent coffee grounds.  

PubMed

The present work highlights the preparation of activated carbons (ACs) using spent coffee grounds, an agricultural residue, as carbon precursor and two different activating agents: water vapor (ACW) and K(2)CO(3) (ACK). These ACs presented the microporous nature and high surface area (620-950 m(2) g(-1)). The carbons, as well as a commercial activated carbon (CAC) used as reference, were evaluated as phenol adsorbent showing high adsorption capacity (?150 mg g(-1)). The investigation of the pH solution in the phenol adsorption was also performed. The different activating agents led to AC with distinct morphological properties, surface area and chemical composition, although similar phenol adsorption capacity was verified for both prepared carbons. The production of activated carbons from spent coffee grounds resulted in promising adsorbents for phenol removal while giving a noble destination to the residue. PMID:22105129

Castro, Cínthia S; Abreu, Anelise L; Silva, Carmen L T; Guerreiro, Mário C

2011-01-01

263

Record Methane Storage in Monolithic and Powdered Activated Carbons  

NASA Astrophysics Data System (ADS)

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

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

2010-03-01

264

Low density microcellular carbon or catalytically impregnated carbon foams and process for their preparation  

DOEpatents

Machinable and structurally stable, low density microcellular carbon, and catalytically impregnated carbon, foams, and process for their preparation, are provided. Pulverized sodium chloride is classified to improve particle size uniformity, and the classified particles may be further mixed with a catalyst material. The particles are cold pressed into a compact having internal pores, and then sintered. The sintered compact is immersed and then submerged in a phenolic polymer solution to uniformly fill the pores of the compact with phenolic polymer. The compact is then heated to pyrolyze the phenolic polymer into carbon in the form of a foam. Then the sodium chloride of the compact is leached away with water, and the remaining product is freeze dried to provide the carbon, or catalytically impregnated carbon, foam.

Hooper, R.W.; Pekala, R.W.

1987-04-30

265

Low density microcellular carbon or catalytically impregnated carbon forms and process for their preparation  

SciTech Connect

Machinable and structurally stable, low density microcellular carbon, and catalytically impregnated carbon, foams, and process for their preparation, are provided. Pulverized sodium chloride is classified to improve particle size uniformity, and the classified particles may be further mixed with a catalyst material. The particles are cold pressed into a compact having internal pores, and then sintered. The sintered compact is immersed and then submerged in a phenolic polymer solution to uniformly fill the pores of the compact with phenolic polymer. The compact is then heated to pyrolyze the phenolic polymer into carbon in the form of a foam. Then the sodium chloride of the compact is leached away with water, and the remaining product is freeze dried to provide the carbon, or catalytically impregnated carbon, foam.

Hopper, R.W.; Pekala, R.W.

1989-02-21

266

Carbon dioxide sequestration by direct mineral carbonation: process mineralogy of feed and products  

SciTech Connect

Direct mineral carbonation was investigated as a process to convert gaseous CO[2] into a geologically stable final form. The process utilizes a slurry of water, with bicarbonate and salt additions, mixed with a mineral reactant, such as olivine (Mg[2]SiO[4]) or serpentine [Mg[3]Si[2]O[5](OH)[4

O'Connor, William K.; Dahlin, David C.; Rush, G.E.; Dahlin, Cheryl L.; Collins, W. Keith

2002-05-01

267

Preparation and characterization of active carbon spheres prepared by chemical activation  

Microsoft Academic Search

Active carbon spheres were prepared by chemical activation using acid-pretreated resin beads, composed of sulfonated polystyrene divinylbenzene. Carbonization and activation were carried out simultaneously at various temperature ranges from 200 to 900°C for 4h, under gentle fluidization conditions facilitated with N2 flow. Effect of temperature on carbon burn-off of precursor and surface area of active carbon spheres was also studied.

Anuradha Baghel; Beer Singh; G. K. Prasad; Pratibha Pandey; P. K. Gutch

2011-01-01

268

Removal of NO over copper supported on activated carbon prepared by electroless plating  

SciTech Connect

The effect of copper metal supported on activated carbon on the catalytic reduction of NO has been studied as a short reaction process. It was observed that the adsorption properties of the activated carbons plated with copper metal slightly decrease with an increasing in the plating time or amount of copper metal, within the range of well-developed micropores. The results of reduction show that the presence of copper metal on activated carbon remarkably promotes the NO reduction conversion with the time on stream in the presence of oxygen. But a marginal decrease in the function of plating time is observed. Meanwhile, the NO conversion is almost constant being about 100% after standing 20 h on stream at 500 C in spite of the absence of oxygen. The effects of plating time, experimental temperature, and oxygen amount in the activated carbons have been discussed concerning the NO-copper and/or NO-carbon catalytic reaction.

Park, B.J.; Park, S.J.; Ryu, S.K.

1999-09-01

269

Heterogeneous mercury reaction chemistry on activated carbon.  

PubMed

Experimental and theory-based investigations have been carried out on the oxidation and adsorption mechanism of mercury (Hg) on brominated activated carbon (AC). Air containing parts per billion concentrations of Hg was passed over a packed-bed reactor with varying sorbent materials at 140 and 30 degrees C. Through X-ray photoelectron spectroscopy surface characterization studies it was found that Hg adsorption is primarily associated with bromine (Br) on the surface, but that it may be possible for surface-bound oxygen (O) to play a role in determining the stability of adsorbed Hg. In addition to surface characterization experiments, the interaction of Hg with brominated AC was studied using plane-wave density functional theory. Various configurations of hydrogen, O, Br, and Hg on the zigzag edge sites of graphene were investigated, and although Hg-Br complexes were found to be stable on the surface, the most stable configurations found were those with Hg adjacent to O. The Hg-carbon (C) bond length ranged from 2.26 to 2.34 A and is approximately 0.1 A shorter when O is a nearest-neighbor atom rather than a next-nearest neighbor, resulting in increased stability of the given configuration and overall tighter Hg-C binding. Through a density of states analysis, Hg was found to gain electron density in the six p-states after adsorption and was found to donate electron density from the five s-states, thereby leading to an oxidized surface-bound Hg complex. PMID:21516937

Wilcox, Jennifer; Sasmaz, Erdem; Kirchofer, Abby; Lee, Sang-Sup

2011-04-01

270

PRODUCTION OF CARBON PRODUCTS USING A COAL EXTRACTION PROCESS  

SciTech Connect

This Department of Energy National Energy Technology Laboratory sponsored project developed carbon products, using mildly hydrogenated solvents to extract the organic portion of coal to create synthetic pitches, cokes, carbon foam and carbon fibers. The focus of this effort was on development of lower cost solvents, milder hydrogenation conditions and improved yield in order to enable practical production of these products. This technology is needed because of the long-term decline in production of domestic feedstocks such as petroleum pitch and coal tar pitch. Currently, carbon products represents a market of roughly 5 million tons domestically, and 19 million tons worldwide. Carbon products are mainly derived from feedstocks such as petroleum pitch and coal tar pitch. The domestic supply of petroleum pitch is declining because of the rising price of liquid fuels, which has caused US refineries to maximize liquid fuel production. As a consequence, the long term trend has a decline in production of petroleum pitch over the past 20 years. The production of coal tar pitch, as in the case of petroleum pitch, has likewise declined significantly over the past two decades. Coal tar pitch is a byproduct of metallurgical grade coke (metcoke) production. In this industry, modern metcoke facilities are recycling coal tar as fuel in order to enhance energy efficiency and minimize environmental emissions. Metcoke production itself is dependent upon the production requirements for domestic steel. Hence, several metcoke ovens have been decommissioned over the past two decades and have not been replaced. As a consequence sources of coal tar are being taken off line and are not being replaced. The long-term trend is a reduction in coal tar pitch production. Thus import of feedstocks, mainly from Eastern Europe and China, is on the rise despite the relatively large transportation cost. To reverse this trend, a new process for producing carbon products is needed. The process must be economically competitive with current processes, and yet be environmentally friendly as well. The solvent extraction process developed uses mild hydrogenation of low cost oils to create powerful solvents that can dissolve the organic portion of coal. The insoluble portion, consisting mainly of mineral matter and fixed carbon, is removed via centrifugation or filtration, leaving a liquid solution of coal chemicals and solvent. This solution can be further refined via distillation to meet specifications for products such as synthetic pitches, cokes, carbon foam and fibers. The most economical process recycles 85% of the solvent, which itself is obtained as a low-cost byproduct from industrial processes such as coal tar or petroleum refining. Alternatively, processes have been developed that can recycle 100% of the solvent, avoiding any need for products derived from petroleum or coal tar.

Dady Dadyburjor; Philip R. Biedler; Chong Chen; L. Mitchell Clendenin; Manoj Katakdaunde; Elliot B. Kennel; Nathan D. King; Liviu Magean; Peter G. Stansberry; Alfred H. Stiller; John W. Zondlo

2004-08-31

271

Constraining the North Pacific carbon sink: biological and physical processes  

NASA Astrophysics Data System (ADS)

The transition zone region of the North Pacific is a notably large sink for atmospheric carbon dioxide on a mean annual basis, though seasonally the region varies between strong wintertime uptake and weak summertime outgassing. Because the direction of air-sea carbon flux is effectively set by the sea surface pCO2, we seek to identify and quantify those processes most responsible for its variability in this region. While changes in temperature, salinity, dissolved inorganic carbon, and alkalinity are all factors that impact sea surface pCO2 on a seasonal basis, on a mean annual basis the region must be maintained as a sink by processes that remove carbon from surface waters: biological drawdown as well as the result of advection/mixing. In this work we constrain the quantitative contribution of each of these processes throughout an annual cycle. The least constrained of these processes is the biological pump, which we estimate in two independent ways: bottom-up, using satellite data-based primary productivity models coupled with export estimates from literature; and top-down, by determining what the biological pump would need to be to maintain the observed sea surface pCO2 values in the region, given our estimates of all the other regulatory processes.

Ayers, J.; Lozier, M.

2010-12-01

272

Sorption properties of active carbons obtained from walnut shells by chemical and physical activation  

Microsoft Academic Search

A technology of obtaining active carbon from common walnut shells is described. The effect of activation methods, temperature and heating mode on the surface properties has been tested. The resulting carbons were characterised by elemental analysis, low-temperature nitrogen sorption and determination of the number of surface oxygen groups. The sorption properties of the active carbons obtained were characterised by determination

Piotr Nowicki; Robert Pietrzak; Helena Wachowska

2010-01-01

273

Characterization of activated carbon, graphitized carbon fibers and synthetic diamond powder using TPD and DRIFTS  

Microsoft Academic Search

A high surface area activated carbon, graphitized carbon fibers and synthetic diamond powder were characterized by X-ray diffraction, temperature-programmed desorption and diffuse reflectance infrared (IR) spectroscopy (DRIFTS). The activated carbon was analyzed as received as well as after either a nitric acid treatment to introduce oxygen functional groups on its surface or a high temperature treatment (HTT) in H2 at

A. Dandekar; R. T. K. Baker; M. A. Vannice

1998-01-01

274

Characteristics of activated carbon produced from biosludge and its use in wastewater post-treatment.  

PubMed

Experimental research into the bench-scale production of activated carbon from waste-activated sludge from water purification, sawdust, peat, and their mixtures, by carbonisation and activation was undertaken. The research work was carried out to determine possible methods of production of cheap activated carbon from local raw materials and to use it in water purification technology. Along with the samples produced, several commercial activated carbons (namely RB-1, F 100, CA (adsorbent from military gas masks), BAY (product of the USSR)) were tested to compare adsorption properties in the adsorption of phenols, xylidines, amines, methylene blue and molasses. It has been found that the activated carbon produced from waste biosludge was of higher quality than that produced from either sawdust or peat, and performed similarly to RB-1 and F100 in adsorption tests. It was also determined that the activated carbon produced from biosludge could possibly be used in the post-treatment of wastewater. Residual sludge from the biological treatment of the wastewater from the purification of oil-shale in the chemical processing industry could cover up to 80% of the need for activated carbon. Some of this activated carbon could be used in the post-treatment of the same water, adsorbing polyalcaline phenols from the initial content of 4 mg l-1 to the demanded level of 1 mg l-1. PMID:11349382

Pikkov, L; Kallas, J; Rüütmann, T; Rikmann, E

2001-02-01

275

Effect of oxygen surface groups on adsorption of benzene derivatives from aqueous solutions onto active carbon samples  

Microsoft Academic Search

The process of adsorption of selected benzene derivatives from aqueous solution is investigated on two carbonaceous materials of differentiated surface properties – quantity of oxygen functional groups. Carbon samples were prepared by removal of external layers from granules of unmodified and oxidized active carbon. The surface and structure characteristics of carbon samples were estimated by various methods. The experimental isotherms

Anna Derylo-Marczewska; Bronislaw Buczek; Andrzej Swiatkowski

2011-01-01

276

The activation characteristics of the decomposition of H2O2 on palladium-carbon catalysts  

NASA Astrophysics Data System (ADS)

The kinetics of catalytic decomposition of H2O2 on palladium-carbon catalysts with various deposited metal distributions in carrier (active carbon) porous granules was studied. The activation parameters ( E a and A 0) of the process were calculated by the Arrhenius equation. A determining factor for the catalytic process was found to be the entropy factor ( A 0), which characterized the formation and dissociation of activated transition complexes. A quantum-chemical study of the electronic structure of palladium-carbon catalysts showed the occurrence of electron density transfer from the carbon matrix to metal clusters and collectivization of their electronic systems. This increased the donor-acceptor ability of the synthesized materials and, as a consequence, their catalytic activity.

Lapko, V. F.; Gerasimyuk, I. P.; Kuts', V. S.; Tarasenko, Yu. A.

2010-06-01

277

[Flue gas desulfurization by a novel biomass activated carbon].  

PubMed

A novel biomass columnar activated carbon was prepared from walnut shell and pyrolusite was added as a catalyst. The activated carbon prepared was used for flue gas desulphurization in a fixed-bed reactor with 16 g of activated carbon. The impact of operating parameters such as SO2 inlet concentration, space velocity, bed temperature, moisture content and O2 concentration on the desulfurization efficiency of activated carbon was investigated. The results showed that both the breakthrough sulfur capacity and breakthrough time of activated carbon decreased with the increase of SO2 inlet concentration within the range of 0.1% -0.3%. The breakthrough sulfur capacity deceased with the increase of space velocity, with optimal space velocity of 600 h(-1). The optimal bed temperature was 80 degrees C, and the desulfurization efficiency can be reduced if the temperature continue to increase. The presence of moisture and oxygen greatly promoted the adsorption of SO2 onto the activated carbon. The best moisture content was 10%. When the oxygen concentrations were between 10% and 13%, the desulfurization performance of activated carbon was the highest. Under the optimal operating conditions, the sulfur capacity of activated carbon was 252 mg x g(-1), and the breakthrough time was up to 26 h when the SO2 inlet concentration was 0.2%. PMID:23798152

Liu, Jie-Ling; Tang, Zheng-Guang; Chen, Jie; Jiang, Wen-Ju; Jiang, Xia

2013-04-01

278

Ammoxidation of active carbons for improvement of supercapacitor characteristics  

Microsoft Academic Search

Modification of active carbon by ammoxidation was used to obtain electrode material with intermediate acidic–basic properties. It allowed advantage to be taken of the pseudocapacitance characteristics of the material for the improvement of the supercapacitor. Precursor fabric from regenerated cellulose was subjected to carbonization, followed by steam activation at 400 and 800°C, respectively. Ammoxidation was carried out with a mixture

K. Jurewicz; K. Babe?; A. ?ió?kowski; H. Wachowska

2003-01-01

279

Removal of target odorous molecules on to activated carbon cloths  

Microsoft Academic Search

Activated carbon materials are adsorbents whose physico-chemical properties are interesting for the treatment of odorous compounds like hydrogen sulfide. Indeed, their structural parameters (pore structure) and surface chemistry (presence of heteroatoms such as oxygen, hydrogen, nitrogen, sulfur, phosphorus) play an important role in H2S removal. The cloth texture of these adsorbents (activated carbon cloths) is particularly adapted for dealing with

L. M. Le Leuch; A. Subrenat; P. Le Cloirec

2004-01-01

280

What Carbon Sources Support Groundwater Microbial Activity in Riparian Forests?  

NASA Astrophysics Data System (ADS)

A major question in riparian research is the source of energy to support subsurface microbial denitrification activity. The supply of microbially-available carbon frequently limits microbial activity in the subsurface. Therefore, identifying the relative importance of carbon sources in the riparian subsurface helps explain the sustainability and spatial heterogeneity of denitrification rates. We have investigated the importance of buried, carbon-rich soil horizons, deep roots and dissolved organic carbon as potential carbon sources to support groundwater denitrification in riparian forests in Rhode Island. We used field observations, laboratory incubations and in-situ experiments to evaluate these sources at four sites in different geomorphic settings. In particular, we measured the 14C-DIC signature and DIC concentration of ambient groundwater and groundwater that had been degassed, re-introduced into the well, and incubated in-situ. Buried horizons appear to be an important source of carbon in the subsurface, as shown by active respiration in laboratory incubations; greater microbial biomass in buried carbon-rich soils compared to surrounding carbon-poor soils; and the presence of very old carbon (>1,000 ybp) in DIC 225 cm beneath the surface. DIC collected from shallower wells showed no clear evidence of ancient carbon. Roots also appear to be important, creating hotspots of carbon availability and denitrification in the generally carbon poor subsurface matrix. Dissolved organic carbon did not stimulate denitrification in aquifer microcosms in the laboratory, suggesting that this was not an important carbon source for denitrification in our sites. Determining which carbon source is fueling denitrification has practical implications. Where buried horizons are the key source, surface management of the riparian zone will likely have little direct influence on groundwater denitrification. Where roots are the key source, changes in the plant community are likely to influence denitrification capacity in the subsurface.

Gurwick, N. P.; Groffman, P. M.; McCorkle, D. C.; Stolt, M. H.; Kellogg, D. Q.; Gold, A. J.

2004-05-01

281

Microbial Enzyme Activity and Carbon Cycling in Grassland Soil Fractions  

NASA Astrophysics Data System (ADS)

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.

Allison, S. D.; Jastrow, J. D.

2004-12-01

282

Thermal regeneration of an activated carbon exhausted with different substituted phenols  

Microsoft Academic Search

The thermal desorption process of phenol, m-aminophenol, p-cresol and p-nitrophenol from an activated carbon has been studied. For this purpose, the activated carbon-phenolic compound system was heated to 1100 K in a He flow following determination of weight loss and the evolution of light gases by a thermobalance and by mass spectrometry, respectively. Results showed that during the heat treatment,

C. Moreno-Castilla; J. Rivera-Utrilla; J. P. Joly; M. V. López-Ramón; M. A. Ferro-García; F. Carrasco-Marín

1995-01-01

283

Ozone Removal by Filters Containing Activated Carbon: A Pilot Study  

SciTech Connect

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

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

2009-09-01

284

Crystallization process of amorphous silicon–carbon alloys  

Microsoft Academic Search

The crystallization behavior of amorphous silicon carbon alloys films was investigated using infrared spectroscopy and transmission electron microscopy. The films were prepared by plasma enhanced chemical vapor deposition and the thickness and composition were checked by Rutherford backscattering spectroscopy. Annealing processes were carried out in the temperature range of 750–1100 °C in a vacuum furnace. The changes in the infrared

L. Calcagno; P Musumeci; F Roccaforte; C Bongiorno; G Foti

2002-01-01

285

Air Pollution Control in the Carbon Baking Process  

Microsoft Academic Search

Carbon baking process involves evolution of fumes containing hydrocarbons and soot particles which cannot be discharged directly into the atmosphere. An incinerator can be used to clean these fumes. However, length of the baking cycle, nature of the fumes and variations in fume volume and temperature may result in excessive auxiliary fuel usage and inefficient incineration, if the incinerator is

Klaus H. Hemsath; Arvind C. Thekdi

1974-01-01

286

Regression analysis study on the carbon dioxide capture process  

Microsoft Academic Search

Research on amine-based carbon dioxide (CO) capture has mainly focused on improving the effectiveness and efficiency of the CO capture process. The objective of our work is to explore relationships among key parameters that affect the CO production rate. From a survey of relevant literature, we observed that the significant parameters influencing the CO production rate include the reboiler heat

Q. Zhou; Christine W. Chan; P. Tontiwachiwuthikul

2008-01-01

287

The active site structure of Thalassiosira weissflogii carbonic anhydrase 1.  

PubMed

X-ray absorption spectroscopy at the Zn K-edge indicates that the active site of the marine diatom Thalassiosira weissflogii carbonic anhydrase is strikingly similar to that of mammalian alpha-carbonic anhydrase enzymes. The zinc has three histidine ligands and a single water at 1.98 A. This is quite different from the beta-carbonic anhydrases of higher plants in which zinc is coordinated by two cysteine thiolates, one histidine, and a water molecule. The diatom carbonic anhydrase shows no significant sequence similarity with other carbonic anhydrases and may represent an example of convergent evolution at the molecular level. PMID:11015190

Cox, E H; McLendon, G L; Morel, F M; Lane, T W; Prince, R C; Pickering, I J; George, G N

2000-10-10

288

Carbon nanotube-reinforced composites: Processing, characterization and modeling  

NASA Astrophysics Data System (ADS)

The exceptionally high specific stiffness and strengths reported for carbon nanotubes, combined with their fiber-like structure, has stimulated research in the development of polymer nanocomposites reinforced with carbon nanotubes. Before these extraordinary properties observed at the nano-scale are realized in a macroscopic composite, considerable basic research is necessary. This research work seeks to obtain a fundamental understanding of the processing/structure/property relations in carbon nanotube-reinforced composites through integrated research on processing and characterization of model nanocomposite systems as well as development of predictive models for the nanocomposite elastic properties. Ultimately, establishment of these basic relationships will enable the nanoscale design of nanotube-reinforced materials. In this work, a novel technique to produce continuous nanocomposite ribbons of aligned multi-walled carbon nanotubes embedded in a polystyrene thermoplastic matrix was developed. This model nanocomposite system serves as a basis for the investigation of structure/property relationships through characterization of their elastic and fracture behavior. Based on characterization results and numerical simulations, a micromechanics-based modeling technique is developed to describe the structure/size influence of the nanotube reinforcement on the elastic modulus of these nanocomposites. To reveal the hierarchy of nanotube reinforcement, multi-scale hybrid composites, where a nanotube composite sheath surrounds traditional carbon fibers, were produced and the influence of selective reinforcement on load transfer at the fiber/matrix interface was examined.

Thostenson, Erik T.

289

DISCOVERY AND ELIMINATION OF DIOXINS FROM A CARBON REACTIVATION PROCESS  

EPA Science Inventory

In a project done to ensure an environmentally acceptable granular activated carbon (GAC) adsorption and reactivation system--to be sure that chlorinated dibenzo-p-dioxins (CDD's) and chlorinated dibenzo furans (CDF's) and combustion would not present problems--results from a GAC...

290

KOH catalysed preparation of activated carbon aerogels for dye adsorption.  

PubMed

Organic carbon aerogels (CAs) were prepared by a sol-gel method from polymerisation of resorcinol, furfural, and hexamethylenetetramine catalysed by KOH at around pH 9 using ambient pressure drying. The effect of KOH in the sol-gel on CA synthesis was studied. It was found that addition of KOH prior to the sol-gel polymerisation process improved thermal stability of the gel, prevented the crystallinity of the gel to graphite, increased the microporosity of CA and promoted activation of CA. The CAs prepared using the KOH catalyst exhibited higher porosity than uncatalysed prepared samples. Activation in CO(2) at higher temperature also enhanced the porosity of CAs. Adsorption tests indicated that the CAs were effective for both basic and acid dye adsorption and the adsorption increased with increasing surface area and pore volume. The kinetic adsorption of dyes was diffusion control and could be described by the second-order kinetic model. The equilibrium adsorption of dyes was higher than activated carbon. PMID:21345448

Ling, Sie King; Tian, H Y; Wang, Shaobin; Rufford, Thomas; Zhu, Z H; Buckley, C E

2011-02-03

291

Gas Adsorption by Activated and Impregnated Carbons.  

National Technical Information Service (NTIS)

In the period reported, equilibrium adsorption isotherms have been measured for CCl4 on carbons 4, 5, and 6. The results have been analyzed in terms of the Dubinin-Polanyi isotherm equation and compared with those obtained for carbons 1, 2, and 3. A brief...

P. J. Reucroft C. P. Madhusudhan

1976-01-01

292

Process, structure and electrochemical properties of carbon nanotube containing films and fibers  

NASA Astrophysics Data System (ADS)

The objective of this thesis is to study the effect of process conditions on structure and electrochemical properties of polyacrylonitrile (PAN)/carbon nanotube (CNT) composite film based electrodes developed for electrochemical capacitors. The process parameters like activation temperature, CNT loading in the composite films are varied to determine optimum process conditions for physical (CO2) and chemical (KOH) activation methods. Films prepared by solution casting, fibers spun by solution spinning, and gel spinning and buckypapers made from SWNT and MWNT were used in this study. The PAN/CNT precursors are stabilized in air, carbonized in inert atmosphere (argon), and activated by physical (CO2) and chemical (KOH) methods. The physical activation process is carried out by heat treating the carbon precursors in CO2 atmosphere at activation temperatures. In the chemical activation process, stabilized carbon precursors are immersed in aqueous solutions of activating media (KOH), dried, and subsequently heat treated in an inert atmosphere at the activation temperature. The structure and morphology are probed using scanning electron microscopy, x-ray diffraction, and fourier transform infrared spectroscopy. The specific capacitance, power and energy density of the activated electrodes are evaluated with aqueous electrolytes (KOH) as well as organic electrolyte (ionic liquid in acetonitrile) in Cell Test. The surface area and pore size distribution of the activated composite electrodes are evaluated using nitrogen absorption. Specific capacitance dependence on factors such as surface area and pore size distribution are studied. Carbon nanotube containing electrode is developed with high specific capacitance, energy density and power density. The process conditions for physical and chemical activation processes were varied and conditions for achieving superior electrochemical properties, surface area and controlled pore size were determined. A maximum specific capacitance of 300 F/g in KOH electrolyte and maximum energy density of 22 wh/kg in ionic liquid has been achieved. BET surface areas in excess of 2500 m2/g with controlled pore sizes in 1--5 nm range has been attained in this work. The specific capacitances of physically and chemically activated samples have direct positive correlation to micropore volume.

Jagannathan, Sudhakar

293

Hydrogen Adsorption on Activated Carbon an Carbon Nanotubes Using Volumetric Differential Pressure Technique  

SciTech Connect

A simple hydrogen adsorption measurement system utilizing the volumetric differential pressure technique has been designed, fabricated and calibrated. Hydrogen adsorption measurements have been carried out at temperatures 298 K and 77 K on activate carbon and carbon nanotubes with different surface areas. The adsorption data obtained will be helpful in understanding the adsorption property of the studied carbon materials using the fundamentals of adsorption theory. The principle of the system follows the Sievert-type method. The system measures a change in pressure between the reference cell, R1 and the sample cell S1, S2, S3 over a certain temperature range, R1, S1, S2, and S3 having known fixed volume. The sample temperatures will be monitored by thermocouple TC while the pressures in R1 an S1, S2, S3 will be measured using a digital pressure transducer. The maximum operating pressure of the pressure transducer is 20 bar and calibrated with an accuracy of +-0.01 bar. High purity hydrogen is being used in the system and the amount of samples for the study is between 1.0-2.0 grams. The system was calibrated using helium gas without any samples in S1, S2 an S3. This will provide a correction factor during the adsorption process providing an adsorption free reference point when using hydrogen gas resulting in a more accurate reading of the adsorption process by eliminating the errors caused by temperature expansion effects and other non-adsorption related phenomena. The ideal gas equation of state is applied to calculate the hydrogen adsorption capacity based on the differential pressure measurements. Activated carbon with a surface area of 644.87 m{sup 2}/g showed a larger amount of adsorption as compared to multiwalled nanotubes (commercial) with a surface area of 119.68 m{sup 2}/g. This study als indicated that there is a direct correlation between the amounts of hydrogen adsorbed an surface area of the carbon materials under the conditions studied and that the adsorption significant at 77 K.

Sanip, S. M.; Saidin, M. A. R.; Aziz, M.; Ismail, A. F. [Membrane Research Unit, Faculty of Chemical and Natural Resources Engineering, Universiti Teknologi Malaysia, 81310, Skudai, Johor (Malaysia)

2010-03-11

294

Carbon nanotube growth activated by quantum-confined silicon nanocrystals  

NASA Astrophysics Data System (ADS)

We report on the use of silicon nanocrystals (Si-ncs) to activate nucleation and growth of carbon nanotubes (CNTs) without using any metal catalyst. Si-ncs with different surface characteristics have been exposed to the same CH4 low-pressure plasma treatment producing quite different results. Specifically, Si-ncs prepared by laser ablation in water have contributed to the formation of micrometre-sized silicon spherical particles. On the other hand, Si-ncs prepared by electrochemical etching did not induce any specific growth while the third type of Si-ncs, prepared by electrochemical etching and treated by a laser fragmentation process, induced the growth of multi-walled CNTs. The different outcomes of the same plasma process are attributed to the diverse surface features presented by the Si-ncs.

Mariotti, D.; Švr?ek, V.; Mathur, A.; Dickinson, C.; Matsubara, K.; Kondo, M.

2013-03-01

295

Studies relevant to the catalytic activation of carbon monoxide  

SciTech Connect

Research activity during the 1991--1992 funding period has been concerned with the following topics relevant to carbon monoxide activation. (1) Exploratory studies of water gas shift catalysts heterogenized on polystyrene based polymers. (2) Mechanistic investigation of the nucleophilic activation of CO in metal carbonyl clusters. (3) Application of fast reaction techniques to prepare and to investigate reactive organometallic intermediates relevant to the activation of hydrocarbons toward carbonylation and to the formation of carbon-carbon bonds via the migratory insertion of CO into metal alkyl bonds.

Ford, P.C.

1992-06-04

296

Adsorption of cadmium from aqueous solutions on sulfurized activated carbon prepared from nut shells  

Microsoft Academic Search

Low-cost activated carbon, derived from nut shells, and its modified sample have been used as replacements for the current expensive methods of removing cadmium from aqueous solutions and waste waters. Adsorption of cadmium onto four kinds of activated carbons has been studied; prepared activated carbon (PAC), commercial activated carbon (CAC), and the sulfurized ones (SPAC & SCAC). The activated carbon

Amir Fouladi Tajar; Tahereh Kaghazchi; Mansooreh Soleimani

2009-01-01

297

Grain-based activated carbons for natural gas storage.  

PubMed

Natural gas has emerged as a potential alternative to gasoline due to the increase in global energy demand and environmental concerns. An investigation was undertaken to explore the technical feasibility of implementing the adsorbed natural gas (ANG) storage in the fuel tanks of motor vehicles with activated carbons from biomass, e.g., sorghum and wheat. The grain-based activated carbons were prepared by chemical activation; the experimental parameters were varied to identify the optimum conditions. The porosity of the resultant activated carbons was evaluated through nitrogen adsorption; and the storage capacity, through methane adsorption. A comparative study was also carried out with commercial activated carbons from charcoal. The highest storage factor attained was 89 for compacted grain-based activated carbons from grain sorghum with a bulk density of 0.65 g/cm(3), and the highest storage factor attained is 106 for compacted commercial activated carbons (Calgon) with a bulk density of 0.70 g/cm(3). The storage factor was found to increase approximately linearly with increasing bulk density and to be independent of the extent of compaction. This implies that the grain-based activated carbons are the ideal candidates for the ANG storage. PMID:19945864

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

2009-11-28

298

CCN activation of pure and coated carbon black particles.  

PubMed

The CCN (cloud condensation nucleus) activation of pure and coated carbon black particles was investigated using the University of Vienna cloud condensation nuclei counter (Giebl, H.; Berner, A.; Reischl, G.; Puxbaum, H.; Kasper-Giebl, A.; Hitzenberger, R. J. Aerosol Sci. 2002, 33, 1623-1634). The particles were produced by nebulizing an aqueous suspension of carbon black in a Collison atomizer. The activation of pure carbon black particles was found to require higher supersaturations than predicted by calculations representing the particles as insoluble, wettable spheres with mobility equivalent diameter. To test whether this effect is an artifact due to heating of the light-absorbing carbon black particles in the laser beam, experiments at different laser powers were conducted. No systematic dependence of the activation of pure carbon black particles on laser power was observed. The observations could be modeled using spherical particles and an effective contact angle of 4-6 degrees of water at their surface. The addition of a small amount of NaCl to the carbon black particles (by adding 5% by mass NaCl to the carbon black suspension) greatly enhanced their CCN efficiency. The measured CCN efficiencies were consistent with Kohler theory for particles consisting of insoluble and hygroscopic material. However, coating the carbon black particles with hexadecanol (a typical film-forming compound with one hydrophobic and one hydrophilic end) efficiently suppressed the CCN activation of the carbon black particles. PMID:16572779

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

2006-02-15

299

Oxidative degradation of trichloroethylene adsorbed on active carbons: Use of microwave energy  

SciTech Connect

Chlorinated hydrocarbon compounds (CHCl), such as chlorinated alkanes/alkenes, benzene and biphenyl etc, represent an important fraction of the industrial hazardous wastes produced. Trichloroethylene (TCE) can be removed from waste streams by adsorption on active carbons. The primary objective of the present work was to study the detoxification in air-stream of TCE adsorbed on different types of active carbons using in situ microwave heating. A secondary objective was to examine the regeneration of used carbons from the effects of repeated cyclic operations (adsorption- detoxification). The experimental study has shown that trichloroethylene adsorbed on active carbon can be oxidatively degradated in presence of microwave radiation. Energy can be transferred efficiently to the reaction sites without losing heat to the surrounding vessel. One of the decomposition product of trichloroethylene is free chlorine which is held very strongly on active carbon. Hydrochloric acid on the other hand seems to be less strongly held and appears in large concentration in the exit gas. Production of free chlorine can be avoided by using chlorohydrocarbon mixed with sufficient internal hydrogen. This is also expected to minimize the problem of carbon regeneration encountered in this study. The results obtained from studies on the oxidative degradation of TCE under microwave radiation are promising in a number of respects: (1) the detoxification of TCE adsorbed on active carbon can be conducted at moderate (<400{degree}C) temperatures, and (2) the used carbon bed can be regenerated. A patent on the process has been issued. 9 refs., 2 figs., 2 tabs.

Varma, R.; Nandi, S.P.

1991-01-01

300

Oxidation of Black Carbon by Biotic and Abiotic Processes  

SciTech Connect

The objectives of this study were to quantify the relative importance of either biotic or abiotic oxidation of biomass-derived black carbon (BC) and to characterize the surface properties and charge characteristics of oxidized particulate BC. We incubated BC and BC-soil mixtures at two different temperatures (30 C and 70 C) with and without microbial inoculation, nutrient additions, or manure amendments for four months. Abiotic processes were more important for oxidation of BC than biotic processes during this short-term incubation, as inoculation with microorganisms did not change any of the measured parameters. Black C incubated at both 30 C and 70 C without microbial activity showed dramatic decreases in pH (in water) from 5.4 to 5.2 and 3.4, as well as increases in cation exchange capacity (CEC at pH 7) by 53% and 538% and in oxygen (O) contents by 4% and 38%, respectively. Boehm titration and Fourier transform infrared (FTIR) spectroscopy suggested that the formation of carboxylic functional groups was the reason for the enhanced CEC during oxidation. The analyses of BC surface properties by X-ray photoelectron spectroscopy (XPS) indicated that the oxidation of BC particles initiated on the surface. Incubation at 30 C only enhanced oxidation on particle surfaces, while oxidation during incubation at 70 C penetrated into the interior of particles. Such short-term oxidation of BC has great significance for the stability of BC in soils as well as for its effects on soil fertility and biogeochemistry.

Cheng, Chih-hsin; Lehmann, Johannes C.; Thies, Janice E.; Burton, Sarah D.; Engelhard, Mark H.

2006-11-01

301

Exposures to carbon dioxide in the poultry processing industry.  

PubMed

The use of dry ice has increased dramatically in poultry processing plants because of changes in the fast food industry. Concentrations of carbon dioxide in four such plants were measured and were found to exceed the Immediately Dangerous to Life and Health Level (50,000 ppm) inside holding coolers where ventilation is poor. In other areas, where dry ice is delivered to poultry packages, time-weighted average exposures can exceed the threshold limit value of 5000 ppm by substantial margins, even if local exhaust ventilation systems are present. Reports of adverse health effects from carbon dioxide exposure and various control measures are reviewed. Recommendations regarding sampling and analytical techniques also are presented. Operators of poultry plants where dry ice is used need to recognize the occupational hazards of exposure to carbon dioxide. PMID:3145684

Jacobs, D E; Smith, M S

1988-12-01

302

Processing and characterization of multi-scale hybrid composites reinforced with nanoscale carbon reinforcements and carbon fibers  

Microsoft Academic Search

Composites with multi-scale reinforcements consisting of multi-walled carbon nanotubes (MWCNTs) or carbon nanofibers (CNFs), along with micron-sized advanced carbon fibers, were processed using electrophoretic deposition (EPD) technique. Both anodic and cathodic electrophoretic deposition processes have been utilized for the deposition of nanoscale reinforcements on carbon fibers. Through hybridization of the reinforcement scales, we have demonstrated significantly improved electrical conductivity and

Sang-Bok Lee; Oyoung Choi; Wonoh Lee; Jin-Woo Yi; Byung-Sun Kim; Joon-Hyung Byun; Myung-Keun Yoon; Hao Fong; Erik T. Thostenson; Tsu-Wei Chou

2011-01-01

303

Nitrogen-promoted active carbons as catalytic supports  

Microsoft Academic Search

Catalytic properties of active carbons treated with N-compounds and promoted with manganese oxides were studied in selective catalytic reduction of NO with ammonia. The following elements of the preparation had a beneficial effect on activity and selectivity of the catalysts: pre-oxidation of active carbon prior to the introduction of N-species, the choice of N-compound, together with the post-treatment procedure, and

T. Grzybek; J. Klinik; M. Motak; H. Papp

2008-01-01

304

Physical and electrochemical study of halide-modified activated carbons  

Microsoft Academic Search

The current thesis aims to improve the electrochemical capacity of activated carbon electrodes, which enjoy prominent position in commercial electrochemical capacitors. Our approach was to develop electrochemical capacity by developing faradaic pseudocapacitance in carbon through a novel mechanochemical modification using iodine and bromine. Various commercial carbons were mechanochemically modified via solid-state iodation and vapour phase iodine-incorporation. The halidation-induced changes in

Prabeer Barpanda

2009-01-01

305

Nomex-derived activated carbon fibers as electrode materials in carbon based supercapacitors  

Microsoft Academic Search

Electrochemical characterization has been carried out for electrodes prepared of several activated carbon fiber samples derived from poly (m-phenylene isophthalamide) (Nomex) in an aqueous solution. Depending on the burn-off due to activation the BET surface area of the carbons was in the order of 1300–2800m2g?1, providing an extensive network of micropores. Their capability as active material for supercapacitors was evaluated

K. Leitner; A. Lerf; M. Winter; J. O. Besenhard; S. Villar-Rodil; F. Suárez-García; A. Martínez-Alonso; J. M. D. Tascón

2006-01-01

306

Use of ozone\\/activated carbon coupling to remove diethyl phthalate from water: Influence of activated carbon textural and chemical properties  

Microsoft Academic Search

The presence of phthalates in the environment and especially in surface waters and sediments is a major environmental concern. The aim of this work was to study diethyl phthalate (DEP) removal by a water treatment process based on the coupling of ozone (O3) and activated carbon (AC). The main objective was to study the influence of AC properties on the

Tatianne Ferreira de Oliveira; Olivier Chedeville; Henri Fauduet; Benoît Cagnon

2011-01-01

307

DEVELOPMENT OF CONTINUOUS SOLVENT EXTRACTION PROCESSES FOR COAL DERIVED CARBON PRODUCTS  

SciTech Connect

The purpose of this DOE-funded effort is to develop continuous processes for solvent extraction of coal for the production of carbon products. These carbon products include materials used in metals smelting, especially in the aluminum and steel industries, as well as porous carbon structural material referred to as ''carbon foam'' and carbon fibers. During this reporting period, efforts have focused on the development of continuous processes for hydrogenation as well as continuous production of carbon foam and coke.

Elliot B. Kennel; Stephen P. Carpenter; Dady Dadyburjor; Manoj Katakdaunde; Liviu Magean; Peter G. Stansberry; Alfred H. Stiller; John W. Zondlo

2005-06-08

308

Diffusion-barrier-free porous carbon monoliths as a new form of activated carbon.  

PubMed

For the practical use of activated carbon (AC) as an adsorbent of CH(4) , tightly packed monoliths with high microporosity are supposed to be one of the best morphologies in terms of storage capacity per apparent volume of the adsorbent material. However, monolith-type ACs may cause diffusion obstacles in adsorption processes owing to their necked pore structures among the densely packed particles, which result in a lower adsorption performance than that of the corresponding powder ACs. To clarify the relationship between the pore structure and CH? adsorptivity, microscopic observations, structural studies on the nanoscale, and conductivity measurements (thermal and electrical) were performed on recently developed binder-free, self-sinterable ACs in both powder and monolithic forms. The monolith samples exhibited higher surface areas and electrical conductivities than the corresponding powder samples. Supercritical CH? adsorption isotherms were measured for each powder and monolith sample at up to 7?MPa at 263, 273, and 303?K to elucidate their isosteric heats of adsorption and adsorption rate constants, which revealed that the morphologies of the monolith samples did not cause serious drawbacks for the adsorption and desorption processes. This will further facilitate the availability of diffusion-barrier-free microporous carbon monoliths as practical CH? storage adsorbents. PMID:23019152

Kubo, Takashi; Sakamoto, Hirotoshi; Fujimori, Toshihiko; Itoh, Tsutomu; Ohba, Tomonori; Kanoh, Hirofumi; Martínez-Escandell, Manuel; Ramos-Fernández, José M; Casco, Mirian; Rodríguez-Reinoso, Francisco; Urita, Koki; Moriguchi, Isamu; Endo, Morinobu; Kaneko, Katsumi

2012-09-28

309

Pharmaceutical wastewater treatment by internal micro?electrolysis–coagulation, biological treatment and activated carbon adsorption  

Microsoft Academic Search

Treatment of pharmaceutical wastewater by the combined process of internal micro?electrolysis and coagulation, biological treatment and activated carbon adsorption was studied. Internal micro?electrolysis and coagulation served as the pretreatment for the wastewater before biological treatment to reduce the contaminants' toxicity to microbes and improve the biodegradability of wastewater to guarantee the smooth operation of the biological process. Biological treatment was

Kangle Wang; Suiqing Liu; Qiang Zhang; Yiliang He

2009-01-01

310

EVALUATION OF POWDERED ACTIVATED CARBON FOR REMOVAL OF TRACE ORGANICS AT NEW ORLEANS, LOUISIANA  

EPA Science Inventory

This research effort studied the effect of powdered activated carbon on the removal of trace organics in the water treatment process at New Orleans, LA. The water treatment processes were modeled in bench scale reactors that allowed control of treatment variables. A series of exp...

311

Activated carbon adsorption of trichloroethylene (TCE) vapor stripped from TCE-contaminated water  

Microsoft Academic Search

Ground water contaminated with trichloroethylene (TCE) used in electronic, electric, dry cleaning and the like industries is often treated by air-stripping. In this treatment process, TCE in its vapor form is stripped from ground water by air stream and sometimes emitted into the atmosphere without any additional treatments. Activated carbon adsorption is one of the practical and useful processes for

Yusaku Miyake; Akiyoshi Sakoda; Hiroaki Yamanashi; Hirotaka Kaneda; Motoyuki Suzuki

2003-01-01

312

Novel adsorption processes for carbon dioxide capture within a IGCC process  

Microsoft Academic Search

There is considerable interest in identifying carbon dioxide capture processes that can be incorporated within Integrated Gasification and Combined Cycle (IGCC) systems. In this paper, two novel adsorption based process configurations are proposed to operate in the temperature window (250–500 ?C) suitable for an IGCC process after the water gas shift reactor. These process configurations are numerically simulated with an in-house

Penny Xiao; Simon Wilson; Gongkui Xiao; Ranjeet Singh; Paul Webley

2009-01-01

313

Metal chlorides loaded on activated carbon to capture elemental mercury.  

PubMed

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. PMID:21235172

Shen, Zhemin; Ma, Jing; Mei, Zhijian; Zhang, Jianda

2010-01-01

314

Characterization of activated carbon prepared from chicken waste and coal  

SciTech Connect

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.

Yan Zhang; Hong Cui; Riko Ozao; Yan Cao; Bobby I.-T. Chen; Chia-Wei Wang; Wei-Ping Pan [Western Kentucky University, Bowling Green, KY (United States). Institute for Combustion Science and Environmental Technology

2007-12-15

315

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

PubMed

In this work, hydrogen peroxide decomposition and oxidation of organics in aqueous medium were studied in the presence of activated carbon prepared from wet blue leather waste. The wet blue leather waste, after controlled pyrolysis under CO(2) flow, was transformed into chromium-containing activated carbons. The carbon with Cr showed high microporous surface area (up to 889 m(2)g(-1)). Moreover, the obtained carbon was impregnated with nanoparticles of chromium oxide from the wet blue leather. The chromium oxide was nanodispersed on the activated carbon, and the particle size increased with the activation time. It is proposed that these chromium species on the carbon can activate H(2)O(2) to generate HO radicals, which can lead to two competitive reactions, i.e. the hydrogen peroxide decomposition or the oxidation of organics in water. In fact, in this work we observed that activated carbon obtained from leather waste presented high removal of methylene blue dye combining the adsorption and oxidation processes. PMID:21752544

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

2011-06-25

316

carbon cycle  

NSDL National Science Digital Library

Life on earth is based on carbon. Living things acquire carbon from their environment - from air, water, soil, and rock and from other living things - through processes such as photosynthesis, respiration and decomposition. The carbon cycle model is a representation of the movement of carbon from sources to sinks through chemical and physical transfers. The carbon cycle activity allows students to see the effect of fossil fuel burning on the carbon cycle.

School, Maryland V.

317

Microstructure and surface properties of lignocellulosic-based activated carbons  

NASA Astrophysics Data System (ADS)

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

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

2013-01-01

318

Elimination of mercury by adsorption onto activated carbon prepared from the biomass material  

Microsoft Academic Search

Following the previous work (Kaghazchi et al., 2010), dealing with applying a combination of two kinds of agricultural wastes to produce a new adsorbent, this study is dedicated to investigate the details of mercury adsorption process from aquatic medium by this adsorbent. So the Mix-ZC activated carbon (the sample prepared by chemical activation of a mixture of pistachio-nut shells and

Neda Asasian; Tahereh Kaghazchi; Mansooreh Soleimani

319

HARDWOOD-BASED GRANULAR ACTIVATED CARBON FOR METALS REMEDIATION  

Technology Transfer Automated Retrieval System (TEKTRAN)

Granular activated carbon is usually the adsorbent of choice for removing organic pollutants from air and water waste streams. Its ability to remove metal ions from aqueous media is considered secondary to its ability to remove organics. Only recently was a coal-based, commercial carbon (Minotaur) m...

320

ELEMENTAL MERCURY CAPTURE BY ACTIVATED CARBON IN A FLOW REACTOR  

EPA Science Inventory

The paper gives results of bench-scale experiments in a flow reactor to simulate the entrained-flow capture of elemental mercury (Hgo) using solid sorbents. Adsorption of Hgo by a lignite-based activated carbon (Calgon FGD) was examined at different carbon/mercury (C/Hg) rat...

321

Ignition and Combustion Properties of Activated Carbon Containing Adsorbed Hydrocarbons.  

National Technical Information Service (NTIS)

Activated carbon contained in large filter beds is used in nuclear submarines for removal of odors and trace contaminants. Because organic vapors are concentrated in this way in the carbon, a study was made to get information for assessing the fire hazard...

F. J. Woods J. E. Johnson

1964-01-01

322

Heterogeneity of active carbons in adsorption of phenol aqueous solutions  

Microsoft Academic Search

Energetic heterogeneity of activated carbons prepared from bituminous coals is investigated on the basis of adsorption isotherms of phenol from the dilute aqueous solutions. The Langmuir–Freundlich (L–F) equation has been used to estimate the monolayer capacity values of carbons studied. Adsorption energy distribution functions have been calculated by using algorithm INTEG based on a regularization method. Analysis of these functions

P. Podkoscielny; A. D; O. V. Marijuk

2003-01-01

323

Noncovalent functionalization of carbon nanotubes with redox active lignin derivatives  

Microsoft Academic Search

Kraft lignin (KL) was adsorbed on multi-wall carbon nanotubes (MWCNTs). After dispersing in dimethylsulfoxide the biopolymer coated MWCNTs formed stable suspensions that could be used to form cast films on glassy carbon electrodes. The composite films after initial oxidation showed redox functions characteristic of quinone moieties. These could be further reacted with thionine (TH) to form a redox active composite

Grzegorz Milczarek

2009-01-01

324

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

SciTech Connect

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

Lin, S.H.; Hsu, F.M. [Yuan Ze Inst. of Tech., Taoyuan (Taiwan, Province of China). Dept. of Chemical Engineering

1995-06-01

325

Adsorption of the aurocyanide, Au ( CN ) 2 - complex on granular activated carbons derived from macadamia nut shells – A preliminary study  

Microsoft Academic Search

In this study, waste macadamia nut shells were investigated for potential use as a hard organic precursor for the production of a granular activated carbon material. The processing of the macadamia shells commenced with the carbonised of the shells under a nitrogen atmosphere. This was followed by the physical activation of the shells under a carbon dioxide atmosphere, which was

Gerrard Eddy Jai Poinern; Gamini Senanayake; Nikunj Shah; Xuan N. Thi-Le; Gordon M. Parkinson; Derek Fawcett

2011-01-01

326

Removal of reactive dyes from aqueous solutions using combined coagulation\\/flocculation and adsorption on activated carbon  

Microsoft Academic Search

The removal of two reactive dyes (Black 5 and Orange 16) was investigated. The objective of this study was to investigate the removal of reactive dyes through a combined treatment process with coagulation\\/adsorption on activated carbon. Activated carbon derived from coconut shells was used as the adsorbent and aluminum chloride was used as the coagulant. In order to obtain the

Franciele Regina Furlan; Laís Graziela de Melo da Silva; Ayres Ferreira Morgado; Antônio Augusto Ulson de Souza; Selene Maria Arruda Guelli Ulson de Souza

2010-01-01

327

Process and apparatus for further processing of pressurized exothermic reactions. [Up to 6 carbon atoms  

Microsoft Academic Search

A continuous process is described for the carbonylation of ..cap alpha..-olefin having up to six carbon atoms for the preparation of a carboxylic acid or ester thereof and for employing the exothermic heat of the reaction to heat the product mixture for subsequent separation of at least one component from the product mixture. The process consists of: (a) reacting a

Pascoe

1986-01-01

328

40 CFR 60.1330 - How do I monitor the injection rate of activated carbon?  

Code of Federal Regulations, 2010 CFR

...the injection rate of activated carbon? 60.1330 Section...AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED...the injection rate of activated carbon? If your municipal...combustion unit uses activated carbon to control...

2010-07-01

329

40 CFR 62.15275 - How do I monitor the injection rate of activated carbon?  

Code of Federal Regulations, 2010 CFR

...the injection rate of activated carbon? 62.15275 Section...AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED...the injection rate of activated carbon? If your municipal...combustion unit uses activated carbon to control...

2009-07-01

330

40 CFR 60.1820 - How do I monitor the injection rate of activated carbon?  

Code of Federal Regulations, 2010 CFR

...the injection rate of activated carbon? 60.1820 Section...AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED...the injection rate of activated carbon? If your municipal...combustion unit uses activated carbon to control...

2010-07-01

331

40 CFR 62.15275 - How do I monitor the injection rate of activated carbon?  

Code of Federal Regulations, 2010 CFR

...the injection rate of activated carbon? 62.15275 Section...AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED...the injection rate of activated carbon? If your municipal...combustion unit uses activated carbon to control...

2010-07-01

332

40 CFR 62.15275 - How do I monitor the injection rate of activated carbon?  

Code of Federal Regulations, 2013 CFR

...monitor the injection rate of activated carbon? 62.15275 Section 62.15275 ...monitor the injection rate of activated carbon? If your municipal waste combustion unit uses activated carbon to control dioxins/furans or...

2013-07-01

333

40 CFR 60.1820 - How do I monitor the injection rate of activated carbon?  

Code of Federal Regulations, 2013 CFR

...monitor the injection rate of activated carbon? 60.1820 Section 60.1820 Protection...monitor the injection rate of activated carbon? If your municipal waste combustion unit uses activated carbon to control dioxins/furans or...

2013-07-01

334

40 CFR 60.1330 - How do I monitor the injection rate of activated carbon?  

Code of Federal Regulations, 2013 CFR

...monitor the injection rate of activated carbon? 60.1330 Section 60.1330 Protection...monitor the injection rate of activated carbon? If your municipal waste combustion unit uses activated carbon to control dioxins/furans or...

2013-07-01

335

Transition metal-catalyzed carbon-carbon bond activation.  

PubMed

This tutorial review deals with recent developments in the activation of C-C bonds in organic molecules that have been catalyzed by transition metal complexes. Many chemists have devised a variety of strategies for C-C bond activation and significant progress has been made in this field over the past few decades. However, there remain only a few examples of the catalytic activation of C-C bonds, in spite of the potential use in organic synthesis, and most of the previously published reviews have dwelt mainly on the stoichiometric reactions. Consequently, this review will focus mainly on the catalytic reaction of C-C bond cleavage by homogeneous transition metal catalysts. The contents include cleavage of C-C bonds in strained and unstrained molecules, and cleavage of multiple C-C bonds such as C[triple bond]C triple bonds in alkynes. Multiple bond metathesis and heterogeneous systems are beyond the scope of this review, though they are also fascinating areas of C-C bond activation. In this review, the strategies and tactics for C-C bond activation will be explained. PMID:15592626

Jun, Chul-Ho

2004-11-04

336

Supercritical Fluid Assisted Synthesis and Processing of Carbon Nanotubes  

SciTech Connect

Carbon nanotubes (CNTs) constitute one of the most fascinating nanomaterials with specific properties and enormous applications. Taking advantages of the unique properties of supercritical fluids (SCFs), various techniques have been developed to produce and process CNTs and related nanostructured materials when conventional techniques become unviable. Herein we propose a critical review of these SCF based techniques. The most relevant characteristics of each technique and the enabled novel structures and functions which are difficult to accomplish by traditional techniques are highlighted.

Ye, Sufang; Wu, Fengming; Ye, Xiangrong; Lin, Yuehe

2009-03-26

337

A statistical analysis of the carbon dioxide capture process  

Microsoft Academic Search

Post combustion carbon dioxide (CO2) capture is one of the most commonly adopted technologies for reducing industrial CO2 emissions, which is now an important goal given the widespread concern over global warming. Research on amine-based CO2 capture has mainly focused on improving effectiveness and efficiency of the CO2 capture process. Our research work focuses on studying the relationships among the

Qing Zhou; Christine W. Chan; Paitoon Tontiwachiwuthikul; Raphael Idem; Don Gelowitz

2009-01-01

338

TESTING GUIDELINES FOR TECHNETIUM-99 ABSORPTION ON ACTIVATED CARBON  

SciTech Connect

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

BYRNES ME

2010-09-08

339

Production of energy and activated carbon from agri-residue: sunflower seed example.  

PubMed

In this work, a biomass processing facility is designed and simulated for the annual conversion of 77 ktons of sunflower residue into electricity and activated carbon. The residue is initially pyrolized to produce low hydrocarbon gases (35 wt%), bio-oils (30 wt%), and char (35 wt%). The gases and bio-oils are separated and combusted to generate high pressure steam, electricity, and steam for conversion of char into activated carbon. Assuming 35% of the char's mass is lost during activation, the proposed process produces 15.6 ktons activated carbon and 5.5 ktons ash annually, while generating 10.2 MW of electricity. Economic analysis of the proposed facility yielded capital costs of $31.64 million, annual operating costs of $31.58 million, and a yearly gross revenue of $38.9 million. A discounted payback period of 6.1 years was determined for the current design, extending to 10 years if the facility were operated at 75% capacity. While the proposed process appears to be economically viable, profitability is highly sensitive to the selling price of electricity and activated carbon, highlighting the need for additional research into the pyrolysis reactor design, char/ash separation techniques, and the quality of activated carbon obtained using char from sunflower residue pyrolysis. PMID:21938425

Donaldson, Adam A; Kadakia, Parag; Gupta, Murlidhar; Zhang, Zisheng

2011-09-21

340

Recovery efficiency of the hydrofluorocarbon (HFC?134a) by activated carbons of different physicochemical properties  

Microsoft Academic Search

The adsorption characteristics of 1,1,1,2?tetrafluoroethane (HFC?134a) on activated carbon were investigated to evaluate the recovery efficiency of HFC?134a by six activated carbons (two granular activated carbons (GAC1 and GAC2), one high?surface area activated carbon (HAC), and three activated carbon fibers (ACF10, ACF15, and ACF20)). HFC?134a adsorption on the activated carbons increased with increase in the specific surface area and pore

Naohito Kawasaki; Seiki Tanada; Takeo Nakamura; Takashi Ohue; Ikuo Abe

1999-01-01

341

Catalytic ozonation of dimethyl phthalate over cerium supported on activated carbon.  

PubMed

Cerium supported on activated carbon (Ce/AC), which was prepared by dipping method, was employed to degrade dimethyl phthalate (DMP) in water. The mineral matter present in the activated carbon positively contributes to its activity to enhance DMP ozonation process. A higher dipping Ce(NO(3))(3) concentration and calcination process increase its microporous volume and surface area, and decreases its exterior surface area. The catalytic activity reaches optimal when 0.2% (w/w) cerium is deposited on activated carbon. Ce/AC catalyst was characterized by XRD, SEM and BET. The presence of either activated carbon or Ce/AC catalyst considerably improves their degradation and mineralization in the ozonation of DMP. During the ozonation (50mg/h ozone flow rate) of a 30 mg/L DMP (initial pH 5.0) with the presence of Ce/AC catalyst, TOC removal rate reaches 68% at 60 min oxidation time, 48% using activated carbon as catalyst, only 22% with ozonation alone. The presence of tert-butanol (a well known OH radical scavenger) strongly inhibits DMP degradation by activated carbon or Ce/AC catalytic ozonation. TOC removal rate follows the second-order kinetics model well. In the ozonation of DMP with 50mg/h ozone flow rate, its mineralization rate constant with the presence of Ce/AC catalyst is 2.5 times higher than that of activated carbon, 7.5 times higher than that of O(3) alone. Ce/AC catalyst shows the better catalytic activity and stability based on 780 min sequential reaction in the ozonation of DMP. Ce/AC was a promising catalyst for ozonizing organic pollutants in the aqueous solution. PMID:19467775

Li, Laisheng; Ye, Weiying; Zhang, Qiuyun; Sun, Fengqiang; Lu, Ping; Li, Xukai

2009-05-04

342

Carbon dioxide absorption in piperazine activated N-methyldiethanolamine  

Microsoft Academic Search

The removal of carbon dioxide from process gas streams is an important step in many industrial processes for a number of technical, economical or environmental reasons. The conventional technology to capture CO2 on large scale is the absorption - desorption process, in which (aqueous) solutions of alkanolamines are frequently used as solvents [Kohl and Nielsen, 1997]. Nowadays, the addition of

Peter Wilhelmus Jacques Derks

2006-01-01

343

Influence of the precursor metamorphism degree on preparation of nitrogen-enriched activated carbons by ammoxidation and chemical activation of coals  

SciTech Connect

The paper presents results of a study on obtaining N-enriched active carbons from four hard coals with different degree of metamorphism. The starting materials were carbonized, activated with KOH, and ammoxidized by a mixture of ammonia and air at the ratio 1:3 at 300 and 350{sup o}C, at each stage of the active carbon production. The efficiency of ammoxidation was found to depend on the degree of metamorphism of the precursor, the stage of processing at which ammoxidation is performed, and the temperature of this process. Ammoxidation of the active carbon led to a decrease in their surface area and pore volume, whereas that performed both at the stage of the precursor and the carbonizate brought improvement of textural parameters of the active carbons obtained. The sequence of the carbonization, activation, and ammoxidation processes had a significant effect on the acid-base character of the active carbon samples obtained. The majority of the active carbons modified at the stage of precursor and carbonizate showed considerable prevalence of surface acidic groups, whereas the samples ammoxidized after activation showed an intermediate acidic-basic character of the surface. 25 refs., 4 figs., 9 tabs.

Piotr Nowicki; Robert Pietrzak; Helena Wachowska [Adam Mickiewicz University, Pozna (Poland). Laboratory of Coal Chemistry and Technology

2009-04-15

344

A process-based understanding of the late Cenozoic carbon cycle  

NASA Astrophysics Data System (ADS)

On a million-year time scale the global carbon cycle and atmospheric CO2 are assumed to be largely determined by the so-called solid Earth processes weathering, sedimentation, and volcanic outgassing. However, it is not clear how much of the observed dynamics in the proxy data constraining the carbon cycle over the Cenozoic might be determined by internal processes of the atmosphere-ocean-biosphere subsystem. Here, we apply for the first time a process-based model of the global carbon cycle in transient simulations over the last 20 Myr to identify the contributions of terrestrial carbon storage, solubility pump and ocean gateways on changes in atmospheric CO2 and marine ?13C. We apply the isotopic carbon cycle box model BICYCLE, which consists of atmosphere, terrestrial biosphere and ocean reservoirs, the latter containing the full marine carbonate system. Our simulation results show that the long-term cooling since the Mid Miocene Climatic Optimum (about 15 Myr BP) leads to an intensification of the solubility pump, and a drop in atmospheric CO2 of up to 100 ppmv. This oceanic carbon uptake is largely counterbalanced by carbon loss from the terrestrial biosphere. The reduction in terrestrial C storage over time including the expansion of C4 grasses during the last 8 Myr might explain half of the long-term decline in deep ocean ?13C and would support high CO2 (400 to 450 ppmv) around 15 Myr BP. The closure of the Tethys and the Central America ocean gateways explains the developing gradient in deep ocean ?13C between the Atlantic and Pacific basin. We furthermore calculate the residuals, which are unexplained by our results and are therefore caused by solid Earth processes. From the residuals a rise in both ocean alkalinity and dissolved inorganic carbon over time is detected as reasons for declining atmospheric CO2 which led to Earth's long-term cooling observed since the Mid Miocene Climate Optimum. Increased continental weathering in combination with changes in volcanic out-gassing of CO2 might explain these changes in marine carbonate chemistry. Around 16 Myr BP we find a prominent regime shift in the carbon cycle-climate system at which the gradient in both deep ocean ?13C and temperature significantly declines. This might be connected with a shrinking seafloor spreading rates which might have caused reduced volcanic activity and thus less CO2 outgassing. The existence of such a regime shift is confirmed if we extend our analysis to deep ocean records of ?18O and ?13C over the whole Cenozoic.

Köhler, P.; van de Wal, R. S. W.; de Boer, B.; Lourens, L. J.; Bintanja, R.; Bickert, T.; Lohmann, G.

2012-04-01

345

Regeneration of Granular Activated Carbon Using Hydrothermal Technology.  

National Technical Information Service (NTIS)

The economic feasibility of using granular activated carbon (GAC) to remove organic contaminants from industrial and municipal wastewater is contingent upon its reuse during multiple adsorption-regeneration cycles (Van Vliet, 1991). The most common proces...

M. D. Sufnarski

1999-01-01

346

Activation Energy Asymptotics Applied to Burning Carbon Particles.  

National Technical Information Service (NTIS)

The method of activation energy asymptotics is used to describe the entire history of a carbon particle suddenly immersed in a hot oxidizing ambient. Under appropriate conditions which are established by the analysis, the history of the particle is shown ...

D. R. Kassoy P. A. Libby

1982-01-01

347

Removal of Trace Organics from Groundwater Using Granular Activated Carbons.  

National Technical Information Service (NTIS)

The purpose of this study was to determine the feasibility of using granular activated carbon for the removal of dissolved organics from ground water. The primary contaminant considered during the testing program was DIMP(Diisopropyl Methyl Phosphonate). ...

1977-01-01

348

Deposition of anatase on the surface of activated carbon  

Microsoft Academic Search

As part of a program looking into utilization of activated carbon prepared from waste material, titanium dioxide was deposited on the surface of active carbon (AC). This will be used in future work as potential photo-catalyst for treatment of chlorinated phenols in aqueous medium. Three different techniques were used: chemical vapour deposition (CVD), direct air-hydrolysis (DAH) and high-temperature impregnation (HTI)

Amjad H. El-Sheikh; Alan P. Newman; Hafid Al-Daffaee; Suki Phull; Neil Cresswell; Steven York

2004-01-01

349

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

NASA Astrophysics Data System (ADS)

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

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

2009-06-01

350

Warm ocean processes and carbon cycling in the Eocene.  

PubMed

Sea surface and subsurface temperatures over large parts of the ocean during the Eocene epoch (55.5-33.7?Ma) exceeded modern values by several degrees, which must have affected a number of oceanic processes. Here, we focus on the effect of elevated water column temperatures on the efficiency of the biological pump, particularly in relation to carbon and nutrient cycling. We use stable isotope values from exceptionally well-preserved planktonic foraminiferal calcite from Tanzania and Mexico to reconstruct vertical carbon isotope gradients in the upper water column, exploiting the fact that individual species lived and calcified at different depths. The oxygen isotope ratios of different species' tests are used to estimate the temperature of calcification, which we converted to absolute depths using Eocene temperature profiles generated by general circulation models. This approach, along with potential pitfalls, is illustrated using data from modern core-top assemblages from the same area. Our results indicate that, during the Early and Middle Eocene, carbon isotope gradients were steeper (and larger) through the upper thermocline than in the modern ocean. This is consistent with a shallower average depth of organic matter remineralization and supports previously proposed hypotheses that invoke high metabolic rates in a warm Eocene ocean, leading to more efficient recycling of organic matter and reduced burial rates of organic carbon. PMID:24043871

John, Eleanor H; Pearson, Paul N; Coxall, Helen K; Birch, Heather; Wade, Bridget S; Foster, Gavin L

2013-09-16

351

Preparation of titanium dioxide\\/activated carbon composites using supercritical carbon dioxide  

Microsoft Academic Search

The penetration of titanium tetraisopropoxide (TTIP) dissolved in supercritical CO2 into the nano-spaces of an activated carbon was studied for the preparation of a TiO2-coated activated carbon. The conversion of TTIP to TiO2 through thermal decomposition was confirmed by evolved gas analysis during heat treatment under a N2 flow. Acetone was detected in the evolved gas, which suggested that some

Narihito Tatsuda; Hiroshi Itahara; Norihiko Setoyama; Yoshiaki Fukushima

2005-01-01

352

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

PubMed

In the present study, the activation features of phosphoric acid have been investigated using waste peach stones as the raw material in the production of granular activated carbon. Thermogravimetry/differential thermal analysis was conducted to characterize the thermal behavior of peach stone and titration method was used to evaluate the adsorption capacity of the produced activated carbon. It was observed that the iodine value of the activated carbon increased with activation temperature. However, temperatures higher than 500 degrees C caused a thermal destruction, which resulted in the decrease of the adsorption capacity. Activation longer than 1.5 h at 500 degrees C resulted in thermal degradation of the porous structure of the activated carbon. The adsorption capacity was enhanced with increasing of amounts of phosphoric acid, however, excessive phosphoric acid caused a decrease in the iodine value. In addition, it was found that the carbon yields generally decreased with activation temperature and activation time. Scanning electron microscopy analysis was conducted to observe the changes in the poros structure of the activated carbon produced in different temperatures. Activation of carbon by phosphoric acid was found to be superior to that by CaCl2 and gas activation. The activated carbon produced from peach stone was applied as an adsorbent in the treatment of synthesized wastewater containing cadmium ion and its adsorption capacity was found to be as good as that of the commercial one. PMID:15137699

Kim, Dong-Su

2004-01-01

353

Use of activated carbon in removal of some radioisotopes from their waste solutions  

Microsoft Academic Search

Removal of some radioisotopes namely (152+154)Eu and 65Zn from radioactive solutions by activated carbon using both batch and column techniques has been performed. Experimental studies were conducted to evaluate and optimize the various process variables, i.e., equilibrium time, carbon dose, solution pH. Sorption data have been interpreted in terms of both Freündlich and Langmuir isotherms. The fixed-bed results indicate the

H. A. Omar; H. Moloukhia

2008-01-01

354

Synthesis and foaming of water expandable polystyrene-activated carbon (WEPSAC)  

Microsoft Academic Search

In this study, water acts as a co-blowing agent to support carbon dioxide (CO2) in the extrusion foaming process of polystyrene (PS) to produce foams with very low density for thermal insulation applications. Herein, we report a simple suspension polymerization method to prepare water expandable polystyrene (WEPS) based on a PS\\/water containing activated carbon (AC) composite. AC pre-saturated with water

Jintao Yang; Shu-Kai Yeh; Nan-Rong Chiou; Zhihua Guo; Thomas Daniel; L. James Lee

2009-01-01

355

Carbon Sequestration Monitoring Activities, (Final Report).  

National Technical Information Service (NTIS)

In its 'Carbon Sequestration Technology Roadmap and Program Plan 2007' the U.S. Department of Energy (DOE)'s Office of Fossil Energy National Energy Technology Laboratory (NETL) identified as a major objective extended field tests to fully characterize po...

C. Frost

2010-01-01

356

Study of activated nitrogen-enriched carbon and nitrogen-enriched carbon\\/carbon aerogel composite as cathode materials for supercapacitors  

Microsoft Academic Search

An activated nitrogen-enriched carbon (ANC) material and a novel activated nitrogen-enriched carbon\\/carbon aerogel (ANC\\/ACA) composite were prepared by carbonization and activation of melamine resin and melamine resin\\/carbon aerogel composite. These were characterized by SEM, XPS, nitrogen adsorption\\/desorption and electrochemical measurements. Findings indicated than the materials had a highly porous nanometer-sized honeycomb structure and high specific surface area. ANC and ANC\\/ACA

Chuanli Qin; Xing Lu; Geping Yin; Zheng Jin; Qiang Tan; Xuduo Bai

2011-01-01

357

Preparing activated carbon from various nutshells by chemical activation with K 2CO 3  

Microsoft Academic Search

We have prepared activated carbons by chemical activation with K2CO3 from five kinds of nutshells: almond shell (AM), coconut shell (CN), oil palm shell (OP), pistachio shell (PT) and walnut shell (WN). When prepared at 1073 K, the activated carbons from all the nutshells had the maximum specific surface areas. According to the maximum values of specific surface areas, the

Jun’ichi Hayashi; Toshihide Horikawa; Isao Takeda; Katsuhiko Muroyama; Farid Nasir Ani

2002-01-01

358

Preparation and characterization of activated carbon from date stones by physical activation with steam  

Microsoft Academic Search

Activated carbons are produced from wastes of Algerian date stones by pyrolysis and physical activation in the presence of water vapor into a heated fixed-bed reactor. The effect of pyrolysis temperature and activation hold time on textural and chemical surface properties of raw date stones and carbon materials produced are studied. As expected, the percentage yield decreases with increase of

Chafia Bouchelta; Mohamed Salah Medjram; Odile Bertrand; Jean-Pierre Bellat

2008-01-01

359

Characteristics of activated carbons prepared from pistachio-nut shells by physical activation  

Microsoft Academic Search

Activated carbons were prepared from pistachio-nut shells, which are one type of lignocellulosic material, by a two-step physical method. The effects of the preparation variables on the activated carbon pore structure were studied, followed by the optimization of these operating parameters. It was found that the activation temperature and dwell time are the important parameters that affect the characteristics of

Ting Yang; Aik Chong Lua

2003-01-01

360

Carbonation of an active serpentinization system  

NASA Astrophysics Data System (ADS)

Carbonation of serpentinite has been invoked to be a promising tool to mitigate large-scale CO2 emissions, however, monitoring the reaction progress during or after CO2-injection and the interpretation of rapidly evolving fluid-rock equilibria remains a critical but challenging task. We report on a hydrothermal experiment where CO2 was injected into an ongoing serpentinization system in order to assess the changes in fluid chemistry and mineralogy during carbonation. In a first step olivine (Fo90) was reacted with a fluid of seawater chlorinity at 300 °C and 350 bars and fluid-to-rock mass ratio of 2. Under these conditions serpentinization of olivine is very rapid and causes the formation of serpentine, brucite and minor amounts of magnetite. Several fluid samples were taken and immediately analyzed for aqueous silica (SiO2,aq), hydrogen (H2,aq) and pH to monitor the reaction progress. As soon as the serpentine-brucite equilibrium was reached we lowered the temperature to 230°C to facilitate the subsequent carbonation of serpentine, brucite and olivine. The lower temperature was used since carbonation reactions appear to be more rapid and equilibrium CO2 levels are lower, facilitating carbonation reactions. Next, we injected about 9 milimoles of CO2 into the flexible-cell hydrothermal apparatus resulting in a dissolved concentration of about 180 mM CO2,aq. The injection of CO2 caused a drastic change in fluid composition. Within six hours the pH decreased from 9 to 6, while the increased levels of SiO2,aq and CO2,aq indicate talc-magnesite saturation. Two days after the injection the concentrations of SiO2,aq and CO2,aq increased to quartz-magnesite saturation. Subsequently SiO2,aq and CO2,aq decreased to values close to the serpentine-talc-magnesite quasi-invariant point and remained virtually fixed until the experiment was opened after 91 days. The solid reaction products were analyzed using a field emission SEM equipped with an Oxford EDS system. In agreement with the fluid chemistry the secondary mineralogy consists of serpentine, talc, magnesite and traces of magnetite; brucite and quartz are absent. Although relict olivine is present at the end of the experiment the fluid chemistry rapidly responded to the dominating secondary mineralogy, as suggested by the lack of quartz. This experiment shows how the fluid chemistry can be used to remotely monitor changes in mineralogy during carbonation of ultramafic rocks, changes that may be difficult to monitor otherwise.

Klein, F.; McCollom, T. M.

2011-12-01

361

Disinfection of bacteria attached to granular activated carbon.  

PubMed Central

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

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

1984-01-01

362

Micromechanism of sulfurizing activated carbon and its ability to adsorb mercury  

NASA Astrophysics Data System (ADS)

To eliminate mercury from coal-fired flue gas, sulfurization of carbons has been found to be the most inexpensive approach to solve the problem of environment contamination by mercury. This study focuses on improving the adsorption capacity of activate carbon loaded with elemental sulfur as an active phase and further use in the removal of mercury vapors from fuel gas. In this paper, equipment such as the scanning electron microscope, specific surface area test machine and fluorescence spectrophotometer are employed to study the ability of the S-loaded activated carbon. The results show that unmodified activate carbon has smooth hole surface and uneven distributed hole size. Pore walls of activate carbon modified became rougher and the hole size distribution is asymmetrical. Sulfur is uniformly distributed and is mainly bonded on the surface of the skeleton of activate carbon. In addition, a small amount of granular sulfur was loaded on the surface of the pore walls. Higher temperature creates smaller pore size and larger microporous volume. Improving the process temperature is conducive to the development of micropore and the distribution of sulfur, and a larger amount of small molecular weight sulfur are created, which is helpful in the removal of HgO through chemical adsorption. The optimum modification temperature and holding time is 550 °C and 60 min, which creates the adsorbents of the max absorption capability of 1227.5 ?g Hg/g.

Wu, Guofang; Xu, Minren; Liu, Qingcai; Yang, Jian; Ma, Dongran; Lu, Cunfang; Lan, Yuanpei

2013-08-01

363

Micromechanism of sulfurizing activated carbon and its ability to adsorb mercury  

NASA Astrophysics Data System (ADS)

To eliminate mercury from coal-fired flue gas, sulfurization of carbons has been found to be the most inexpensive approach to solve the problem of environment contamination by mercury. This study focuses on improving the adsorption capacity of activate carbon loaded with elemental sulfur as an active phase and further use in the removal of mercury vapors from fuel gas. In this paper, equipment such as the scanning electron microscope, specific surface area test machine and fluorescence spectrophotometer are employed to study the ability of the S-loaded activated carbon. The results show that unmodified activate carbon has smooth hole surface and uneven distributed hole size. Pore walls of activate carbon modified became rougher and the hole size distribution is asymmetrical. Sulfur is uniformly distributed and is mainly bonded on the surface of the skeleton of activate carbon. In addition, a small amount of granular sulfur was loaded on the surface of the pore walls. Higher temperature creates smaller pore size and larger microporous volume. Improving the process temperature is conducive to the development of micropore and the distribution of sulfur, and a larger amount of small molecular weight sulfur are created, which is helpful in the removal of HgO through chemical adsorption. The optimum modification temperature and holding time is 550 °C and 60 min, which creates the adsorbents of the max absorption capability of 1227.5 ?g Hg/g.

Wu, Guofang; Xu, Minren; Liu, Qingcai; Yang, Jian; Ma, Dongran; Lu, Cunfang; Lan, Yuanpei

2013-11-01

364

Oxidative Process for Cutting Single-Walled Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

Cut single-walled carbon nanotubes (SWNTs) are needed for many applications. An efficient way to produce bulk amounts of cut SWNTs is a two step process consisting of sidewall damage and oxidative exploitation. In these experiments sidewall damage is introduced by ozonation in a perfluoropolyether (PFPE) while monitoring the degree of functionalization with in-situ Raman spectroscopy. Use of PFPE allows for a high degree of sidewall functionalization at room temperature, mainly in the form of epoxides. These damaged SWNTs are exposed to piranha (4:1 96%H2SO4:H2O2) for one hour and then quenched. The piranha exposed samples are then functionalized with alkyl groups and spin cast on mica for length analysis. The cut samples are found to have significantly shorter lengths while maintaining a relatively high carbon yield.

Shaver, Jonah

2005-03-01

365

Detecting Extracellular Carbonic Anhydrase Activity Using Membrane Inlet Mass Spectrometry  

PubMed Central

Current research into the function of carbonic anhydrases in cell physiology emphasizes the role of membrane-bound carbonic anhydrases, such as carbonic anhydrase IX that has been identified in malignant tumors and is associated with extracellular acidification as a response to hypoxia. We present here a mass spectrometric method to determine the extent to which total carbonic anhydrase activity is due to extracellular carbonic anhydrase in whole cell preparations. The method is based on the biphasic rate of depletion of 18O from CO2 measured by membrane inlet mass spectrometry. The slopes of the biphasic depletion are a sensitive measure of the presence of carbonic anhydrase outside and inside of the cells. This property is demonstrated here using suspensions of human red cells in which external carbonic anhydrase was added to the suspending solution. It is also applied to breast and prostate cancer cells which both express exofacial carbonic anhydrase IX. Inhibition of external carbonic anhydrase is achieved by use of a membrane impermeant inhibitor that was synthesized for this purpose, p-aminomethylbenzenesulfonamide attached to a polyethyleneglycol polymer.

Delacruz, Joannalyn; Mikulski, Rose; Tu, Chingkuang; Li, Ying; Wang, Hai; Shiverick, Kathleen T.; Frost, Susan C.; Horenstein, Nicole A.; Silverman, David N.

2010-01-01

366

Catalytic activity of palladium supported on single wall carbon nanotubes compared to palladium supported on activated carbon  

Microsoft Academic Search

Nanoparticles (2–10nm) of palladium have been deposited on single wall carbon nanotubes (SWNT) by spontaneous reduction from Pd(OAc)2 or from oxime carbapalladacycle. These catalysts exhibit higher catalytic activity than palladium over activated carbon (Pd\\/C) for the Heck reaction of styrene and iodobenzene and for the Suzuki coupling of phenylboronic and iodobenzene. This fact has been attributed as reflecting the dramatic

Avelino Corma; Hermenegildo Garcia; Antonio Leyva

2005-01-01

367

Preparation of mesoporous carbon by steam activation of commercial activated carbon in the presence of yttrium oxide  

Microsoft Academic Search

Mesoporous carbon was prepared by steam activation of commercial activated carbon in the presence of yttrium oxide. The loading of yttrium nitrate (precursor of yttrium oxide) was 0.2, 0.6, 1.0 and 2.0 wt%. The weight lost and gases formed during heating were detected by using thermogravimetric analysis and mass spectroscopy. The surface area and the total volume of the mesoporous

W. Z. Shen; J. T. Zheng; Y. L. Zhang; J. G. Wang; Z. F. Qin

2003-01-01

368

Effect of activated carbon content in TiO 2-loaded activated carbon on photodegradation behaviors of dichloromethane  

Microsoft Academic Search

The effect of the amount of TiO2 loading on activated carbon support on the photodecomposition of dichloromethane was studied. The apparent adsorption constant of the TiO2-loaded activated carbon for dichloromethane was found to decrease with increase of the fraction of the loaded TiO2. It was found that the apparent rate constant of CO2 evolution became small with increase of the

Tsukasa Torimoto; Yasuhiro Okawa; Norihiko Takeda; Hiroshi Yoneyama

1997-01-01

369

Electroless copper deposition on a pitch-based activated carbon fiber and an application for NO removal  

Microsoft Academic Search

Pitch fibers were prepared from petroleum-derived isotropic pitch precursors using melt-blown spinning. Activated carbon fibers (ACF) were formed from pitch fibers and after stabilization, carbonization and steam thermal activation were then further activated with Pd–Sn catalytic nuclei in a single-step process. The activated ACF were then used as supporters in the specific, electroless deposition of fine copper particles. Field emission

Jeong Hoon Byeon; Hee Seung Yoon; Ki Young Yoon; Seung Kon Ryu; Jungho Hwang

2008-01-01

370

Activated Carbon Composites for Air Separation  

Microsoft Academic Search

In continuation of the development of composite materials for air separation based on molecular sieving properties and magnetic fields effects, several molecular sieve materials were tested in a flow system, and the effects of temperature, flow conditions, and magnetic fields were investigated. New carbon materials adsorbents, with and without pre-loaded super-paramagnetic nanoparticles of Fe3O4 were synthesized; all materials were packed

Cristian I Contescu; Frederick S Baker; Costas Tsouris; Joanna McFarlane

2008-01-01

371

A comparative study of the adsorption equilibrium of progesterone by a carbon black and a commercial activated carbon  

NASA Astrophysics Data System (ADS)

In this paper the adsorption process of a natural steroid hormone (progesterone) by a carbon black and a commercial activated carbon has been studied. The corresponding equilibrium isotherms have been analyzed according to a previously proposed model which establishes a kinetic law satisfactorily fitting the C versus t isotherms. The analysis of the experimental data points out the existence of two well-defined sections in the equilibrium isotherms. A general equation including these two processes has been proposed, the global adsorption process being fitted to such equation. From the values of the kinetic equilibrium constant so obtained, values of standard average adsorption enthalpy ( ?H°) and entropy ( ?S°) have been calculated. Finally, information related to variations of differential adsorption enthalpy ( ?H) and entropy ( ?S) with the surface coverage fraction ( ?) was obtained by using the corresponding Clausius-Clapeyron equations.

Valenzuela-Calahorro, Cristóbal; Navarrete-Guijosa, Antonio; Stitou, Mostafa; Cuerda-Correa, Eduardo M.

2007-04-01

372

Analysis of hydrogen sorption characteristics of boron-doped activated carbons  

NASA Astrophysics Data System (ADS)

There is significant interest in the properties of boron-doped activated carbons for their potential to improve hydrogen storage.ootnotetextSee http://all-craft.missouri.edu Boron-doped activated carbons have been produced using a novel process involving the pyrolysis of a boron containing compound and subsequent high-temperature annealing. In this talk we will present a systematic study of the effect of different boron doping processes on the samples' surface area, micropore structure, and hydrogen sorption. Experimental results include boron content from prompt gamma neutron activation analysis, boron-carbon chemistry from Fourier transform infrared spectroscopy (FTIR), nitrogen subcritical adsorption, and 80K and 90K hydrogen adsorption isotherms which allow us to evaluate the hydrogen binding energy for each sorptive material.

Beckner, M.; Romanos, J.; Stalla, D.; Dohnke, E.; Singh, A.; Lee, M.; Suppes, G.; Hawthorne, M. F.; Yu, P.; Wexler, C.; Pfeifer, P.

2011-03-01

373

Removal of lead (II) ions from aqueous solutions onto activated carbon derived from waste biomass.  

PubMed

The removal of lead (II) ions from aqueous solutions was carried out using an activated carbon prepared from a waste biomass. The effects of various parameters such as pH, contact time, initial concentration of lead (II) ions, and temperature on the adsorption process were investigated. Energy Dispersive X-Ray Spectroscopy (EDS) analysis after adsorption reveals the accumulation of lead (II) ions onto activated carbon. The Langmuir and Freundlich isotherm models were applied to analyze equilibrium data. The maximum monolayer adsorption capacity of activated carbon was found to be 476.2?mg?g?¹. The kinetic data were evaluated and the pseudo-second-order equation provided the best correlation. Thermodynamic parameters suggest that the adsorption process is endothermic and spontaneous. PMID:23853528

Erdem, Murat; Ucar, Suat; Karagöz, Selhan; Tay, Turgay

2013-06-18

374

Removal of Lead (II) Ions from Aqueous Solutions onto Activated Carbon Derived from Waste Biomass  

PubMed Central

The removal of lead (II) ions from aqueous solutions was carried out using an activated carbon prepared from a waste biomass. The effects of various parameters such as pH, contact time, initial concentration of lead (II) ions, and temperature on the adsorption process were investigated. Energy Dispersive X-Ray Spectroscopy (EDS) analysis after adsorption reveals the accumulation of lead (II) ions onto activated carbon. The Langmuir and Freundlich isotherm models were applied to analyze equilibrium data. The maximum monolayer adsorption capacity of activated carbon was found to be 476.2?mg?g?1. The kinetic data were evaluated and the pseudo-second-order equation provided the best correlation. Thermodynamic parameters suggest that the adsorption process is endothermic and spontaneous.

Erdem, Murat; Ucar, Suat; Karagoz, Selhan; Tay, Turgay

2013-01-01

375

Potential application of activated carbon from maize tassel for the removal of heavy metals in water  

NASA Astrophysics Data System (ADS)

Water-pollution problems worldwide have led to an acute shortage of clean and pure water for both domestic and human consumption. Various technologies and techniques are available for water treatment which includes the use of activated carbon. In this study activated carbons used for the removal of lead (II) ions from water samples were prepared from maize tassels (an agricultural waste residue) which were modified using physical and chemical activation. In the physical activation CO2 was used as the activating agent, while in chemical activation H3PO4 with an impregnation ratio ranging from 1 to 4 was employed. The maize tassel was pyrolysed at different temperatures ranging from 300 °C to 700 °C in an inert atmosphere for a period of 60 min and activated at 700 °C for 30 min. The effects of activation temperature, impregnation ratio and duration were examined. The resultant modified tassels were characterised by measuring their particle-size distribution, porosities, pore volume, and pore-size distribution using scanning electron microscopy (SEM). The activated carbon produced by chemical activation had the highest BET surface area ranging from 623 m2 g-1 to 1 262 m2 g-1. The surface chemistry characteristics of the modified tassels were determined by FT-IR spectroscopy and Boehm's titration method. The experimental data proved that properties of activated carbon depend on final temperature of the process, impregnation ratio and duration of the treatment at final temperature. The adsorption studies showed that chemically prepared activated carbon performed better than physically prepared activated carbon.

Olorundare, O. F.; Krause, R. W. M.; Okonkwo, J. O.; Mamba, B. B.

376

Comparisons of sorbent cost for the removal of Ni2+ from aqueous solution by carbon nanotubes and granular activated carbon.  

PubMed

The reversibility of Ni2+ sorption by NaOCl oxidized single-walled carbon nanotubes (SWCNTs), multiwalled carbon nanotubes (MWCNTs) and granular activated carbon (GAC) was investigated to evaluate their repeated availability performance in water treatment. Under the same conditions, the SWCNTs and MWCNTs possess more Ni2+ sorption capacities and show better reversibility of Ni2+ sorption and less weight loss after being repeated sorption/desorption processes than the GAC, suggesting that they are effective Ni2+ sorbents and can be reused through many cycles of water treatment and regeneration. A statistical analysis on the replacement cost of these sorbents revealed that SWCNTs and MWCNTs can be possibly cost-effective Ni2+ sorbents in water treatment regardless of their high unit cost at the present time. PMID:17618049

Lu, Chungsying; Liu, Chunti; Rao, Gadupudi Purnachadra

2007-06-02

377

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

SciTech Connect

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

Nick Soelberg; Joe Enneking

2011-05-01

378

FENTON-DRIVEN REGENERATION OF GRANULAR ACTIVATED CARBON: A TECHNOLOGY OVERVIEW  

EPA Science Inventory

A Fenton-driven mechanism for regenerating spent granular activated carbon (GAC) involves the combined, synergistic use of two reliable and well established treatment technologies - adsorption onto activated carbon and Fenton oxidation. During carbon adsorption treatment, enviro...

379

The activated sludge process: Fundamentals of operation  

Microsoft Academic Search

The procedures given here - based on extensive and intensive experience. Background information on process mechanics is followed by detailed consideration of control and troubleshooting practices. Contents: PREFACE AND INTRODUCTION; PROCESS MECHANICS; Basic Mechanism of Activated Sludge Systems; Formation of Activated Sludge; Growth of Microorganisms; Classifications of Microorganisms: Type, Environment, Age; Solids Separation and Return; FACTORS AFFECTING OPERATION; Raw Wastewater

R. Junkins; K. J. Deeny; T. H. Eckhoff

1983-01-01

380

Adsorption Equilibria Between Activated Carbon and Organic Compounds in Water Studied in Multicomponent Systems of Known and Unknown Composition.  

National Technical Information Service (NTIS)

An empirical equation is presented to describe the adsorption of organic materials, which are relevant in water treatment processes, on activated carbon surfaces. In the case of multicomponent systems this equation also describes the displacement of mater...

B. R. Frick

1980-01-01

381

A comparison of the electrochemical behavior of carbon aerogels and activated carbon fiber cloths  

SciTech Connect

Electrochemical capacitative behavior of carbon aerogels and commercial carbon fiber cloths was studied in 5M KOH, 3M sulfuric acid, and 0.5M tetrethylammonium tetrafluoroborate/propylene carbonate electrolytes. The resorcinol-formaldehyde based carbon aerogels with a range of denisty (0.2-0.85 g/cc) have open-cell structures with ultrafine pore sizes (5-50 nm), high surface area (400-700 m{sup 2}/g), and a solid matrix composed of interconnected particles or fibers with characteristic diameters of 10 nm. The commercial fiber cloths in the density range 0.2-04g/cc have high surface areas (1000-2500 m{sup 2}/g). The volumetric capacitances of high-density aerogels are shown to be comparable to or exceeding those from activated carbon fibers. Electrochemical behavior of these materials in various electrolytes is compared and related to their physical properties.

Tran, T.D.; Alviso, C.T.; Hulsey, S.S.; Nielsen, J.K.; Pekala, R.W.

1996-05-10

382

Removal of congo red using activated carbon and its regeneration.  

PubMed

Activated carbon is used for the removal of colored toxic congo red dye. The effects of different operating conditions like, initial dye concentration, contact time, pH and temperature are studied for adsorption of congo red by a known amount of activated carbon (1.0g/L) under stirred batch condition. The zero point of charge of the activated carbon is found about 6.6. About 90% dye is removed for initial concentration of 50 and 100mg/L, it is about 80% at pH 7.0. Maximum adsorption (about 100%) of dye is observed at pH 2.0 for the concentration range studied here. Freundlich isotherm is found to fit the equilibrium data more adequately. Pseudo second order kinetic model explain successfully the kinetic data. The surfactant enhanced carbon regeneration (SECR) technique using both cationic and anionic surfactants is adopted for the regeneration of spent carbon by desorbing the dye. A kinetic model for dye desorption from the commercial activated carbon (CAC) is also proposed. Anionic surfactants show better performance than the cationic ones. Efficiency of dye desorption using surfactants is also compared with the desorption using pH change. PMID:17178190

Purkait, M K; Maiti, A; DasGupta, S; De, S

2006-11-18

383

Mechanisms of Activated Carbon Degradation by Perspiration.  

National Technical Information Service (NTIS)

These investigations covered two distinct subjects: activated charcoal degradation by perspiration and decomposition of chloramine B. Both untreated and treated activated charcoal samples were exposed to synthetic sweat solutions or aqueous solutions of i...

L. L. Pytlewski

1977-01-01

384

NAVAL STORES WASTEWATER PURIFICATION AND REUSE BY ACTIVATED CARBON TREATMENT  

EPA Science Inventory

This report documents the reasons for selecting a physico-chemical process instead of a more conventional biological process for secondary treatment of the complex organic wastewaters generated by a Naval Stores manufacturing plant. The selected carbon adsorption system is then d...

385

Carbon Oxysulfide Inhibition of the CO2-Concentrating Process of Unicellular Green Algae 1  

PubMed Central

Carbonyl sulfide (COS), a substrate for carbonic anhydrase, inhibited alkalization of the medium, O2 evolution, dissolved inorganic carbon accumulation, and photosynthetic CO2 fixation at pH 7 or higher by five species of unicellular green algae that had been air-adapted for forming a CO2-concentrating process. This COS inhibition can be attributed to inhibition of external HCO3? conversion to CO2 and OH? by the carbonic anhydrase component of an active CO2 pump. At a low pH of 5 to 6, COS stimulated O2 evolution during photosynthesis by algae with low CO2 in the media without alkalization of the media. This is attributed to some COS hydrolysis by carbonic anhydrase to CO2. Although COS had less effect on HCO3? accumulation at pH 9 by a HCO3? pump in Scenedesmus, COS reduced O2 evolution probably by inhibiting internal carbonic anhydrases. Because COS is hydrolyzed to CO2 and H2S, its inhibition of the CO2 pump activity and photosynthesis is not accurate, when measured by O2 evolution, by NaH14CO3 accumulation, or by 14CO2 fixation.

Goyal, Arun; Shiraiwa, Yoshihiro; Tolbert, N. Edward

1992-01-01

386

Adsorption of phenol from aqueous solutions using mesoporous carbon prepared by two-stage process  

Microsoft Academic Search

Porous carbon prepared from rice husk using phosphoric acid activation through precarbonization and chemical activation has been examined for the adsorption of phenol from aqueous solutions. The method adopted could produce carbons with micro and mesoporous structure. The surface area, pore volume and pore size distribution of carbon samples activated at three different temperatures 700, 800 and 900°C have been

L. John Kennedy; J. Judith Vijaya; K. Kayalvizhi; G. Sekaran

2007-01-01

387

Survival of selected bacterial species in sterilized activated carbon filters and biological activated carbon filters.  

PubMed Central

The survival of selected hygienically relevant bacterial species in activated carbon (AC) filters on a bench scale was investigated. The results revealed that after inoculation of the test strains the previously sterilized AC absorbed all bacteria (10(6) to 10(7)). After a period of 6 to 13 days without countable bacteria in the effluent, the numbers of Escherichia coli, Pseudomonas aeruginosa, and Pseudomonas putida increased up to 10(4) to 10(5) CFU/ml of effluent and 10(6) to 10(7) CFU/g of AC. When Klebsiella pneumoniae and Streptococcus faecalis were used, no growth in filters could be observed. The numbers of E. coli, P. aeruginosa, and P. putida, however, decreased immediately and showed no regrowth in nonsterile AC from a filter which had been continuously connected to running tap water for 2 months. Under these conditions an autochthonous microflora developed on the carbon surface which could be demonstrated by scanning electron microscopy and culturing methods (heterotrophic plate count). These bacteria reduced E. coli, P. aeruginosa, and P. putida densities in the effluent by a factor of more than 10(5) within 1 to 5 days. The hypothesis that antagonistic substances of the autochthonous microflora were responsible for the elimination of the artificial contamination could not be confirmed because less than 1% of the isolates of the autochthonous microflora were able to produce such substances as indicated by in vitro tests. Competition for limiting nutrients was thought to be the reason for the observed effects.

Rollinger, Y; Dott, W

1987-01-01

388

Improved Bioethanol Production Using Activated Carbon-treated Acid Hydrolysate from Corn Hull in Pachysolen tannophilus  

PubMed Central

To optimally convert corn hull, a byproduct from corn processing, into bioethanol using Pachysolen tannophlius, we investigated the optimal conditions for hydrolysis and removal of toxic substances in the hydrolysate via activated carbon treatment as well as the effects of this detoxification process on the kinetic parameters of bioethanol production. Maximum monosaccharide concentrations were obtained in hydrolysates in which 20 g of corn hull was hydrolyzed in 4% (v/v) H2SO4. Activated carbon treatment removed 92.3% of phenolic compounds from the hydrolysate. When untreated hydrolysate was used, the monosaccharides were not completely consumed, even at 480 h of culture. When activated carbon-treated hydrolysate was used, the monosaccharides were mostly consumed at 192 h of culture. In particular, when activated carbon-treated hydrolysate was used, bioethanol productivity (P) and specific bioethanol production rate (Qp) were 2.4 times and 3.4 times greater, respectively, compared to untreated hydrolysate. This was due to sustained bioethanol production during the period of xylose/arabinose utilization, which occurred only when activated carbon-treated hydrolysate was used.

Seo, Hyeon-Beom; Kim, Seungseop; Lee, Hyeon-Yong

2009-01-01

389

Tubular carbon nano-/microstructures synthesized from graphite powders by an in situ template process.  

PubMed

Through the use of commercial graphite powders as the carbon sources, a variety of interesting tubular carbon nano- and microstructures, such as networked carbon nanotubes, aligned carbon microtubes with hexagonal cross-sections, aligned tapered carbon tubes, and hollow carbon microhorns, have been successfully synthesized. As-grown tubular carbon structures were characterized using scanning electron microscopy, transmission electron microscopy, and X-ray energy-dispersive spectroscopy. An in situ template mechanism was proposed to explain the possible growth process. The vibrational properties of the synthesized tubular carbon structures were also studied by Raman spectroscopy. PMID:16771318

Shen, Guozhen; Bando, Yoshio; Zhi, Chunyi; Golberg, Dmitri

2006-06-01

390

Bacteria associated with granular activated carbon particles in drinking water.  

PubMed Central

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

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

1986-01-01

391

Porous texture evolution in Nomex-derived activated carbon fibers.  

PubMed

In the present work, the textural evolution of a series of activated carbon fibers with increasing burn-off degree, prepared by the pyrolysis and steam activation of Nomex aramid fibers, is followed by measurements of physical adsorption of N(2) (77 K) and CO(2) (273 K) and immersion calorimetry into different liquids (dichloromethane, benzene, cyclohexane). The immersion calorimetry results are discussed in depth, paying special attention to the choice of the reference material. The activated carbon fibers studied possess an essentially homogeneous microporous texture, which suggests that these materials may be applied in gas separation, either directly or with additional CVD treatment. PMID:16290775

Villar-Rodil, S; Denoyel, R; Rouquerol, J; Martínez-Alonso, A; Tascón, J M D

2002-08-01

392

Hierarchical macroporous carbon processed with ethylene glycol and starch as double porogens  

Microsoft Academic Search

A hierarchical macroporous carbon derived from phenol–formaldehyde (PF) resin was processed using ethylene glycol (EG) and starch as double porogens. The influences of carbonization temperature on morphological properties and pore microstructure of the porous carbon were investigated, and the formations of hierarchical macropores were analyzed. Obtained results demonstrated that both the carbonization temperature and the composition of the resin and

Guiwu Liu; Jie Li; Guanjun Qiao; Shunjian Xu; Hongjie Wang; Tianjian Lu

2010-01-01

393

Processing, Structure, and Properties of Fibers from PMMA\\/ Carbon Nano Fiber Composites  

Microsoft Academic Search

Single and multi wall carbon nano tubes as well as carbon nano fibers are being used to reinforce both thermoplastics as well as thermoset polymer matrices. While single wall carbon nano tubes are available in limited quantities and are relatively expensive, vapor grown carbon nano fibers are available at relatively low cost and in significant quantities. We are processing composite

Jijun Zeng; Satish Kumar

2002-01-01

394

Robust analysis of the active disassembly process  

Microsoft Academic Search

This paper explores a means to control the active disassembly (AD) process for designed and manufactured heat-activated shape memory polymer snap-fits. Testing was performed for demonstration of the active release of the SMP snap-fits and for analysis of AD control factors. Robust design methodologies with Taguchi methods were used to analyze the AD process factors, including heating method and disassembly

John Carrell; Derrick Tate; Hong-Chao Zhang

2010-01-01

395

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

Microsoft Academic Search

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 °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

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

2002-01-01

396

Activated Carbon Composites for Air Separation  

SciTech Connect

In continuation of the development of composite materials for air separation based on molecular sieving properties and magnetic fields effects, several molecular sieve materials were tested in a flow system, and the effects of temperature, flow conditions, and magnetic fields were investigated. New carbon materials adsorbents, with and without pre-loaded super-paramagnetic nanoparticles of Fe3O4 were synthesized; all materials were packed in chromatographic type columns which were placed between the poles of a high intensity, water-cooled, magnet (1.5 Tesla). In order to verify the existence of magnetodesorption effect, separation tests were conducted by injecting controlled volumes of air in a flow of inert gas, while the magnetic field was switched on and off. Gas composition downstream the column was analyzed by gas chromatography and by mass spectrometry. Under the conditions employed, the tests confirmed that N2 - O2 separation occurred at various degrees, depending on material's intrinsic properties, temperature and flow rate. The effect of magnetic fields, reported previously for static conditions, was not confirmed in the flow system. The best separation was obtained for zeolite 13X at sub-ambient temperatures. Future directions for the project include evaluation of a combined system, comprising carbon and zeolite molecular sieves, and testing the effect of stronger magnetic fields produced by cryogenic magnets.

Contescu, Cristian I [ORNL; Baker, Frederick S [ORNL; Tsouris, Costas [ORNL; McFarlane, Joanna [ORNL

2008-03-01

397

Carbonization of bamboo and consecutive low temperature air activation  

Microsoft Academic Search

Raw moso bamboo (Phyllostachys pubescens) was examined to optimize the carbonization and the consecutive air activation procedure. Influence of sample size, nitrogen\\u000a flow rate, heating rate and final temperature on the carbon yield and the pore structure was investigated for the raw bamboo.\\u000a The short length cutting along bamboo trunk and the increase in heating rate to 40°C\\/min and nitrogen

Noriyuki Yamashita; Motoi Machida

398

Analysis of carbon soil content by using tagged neutron activation  

NASA Astrophysics Data System (ADS)

Here we describe a prototype for non-destructive, in-situ, accurate and cost-effectively measurement procedure of carbon in soil based on neutron activation analysis using 14 MeV tagged neutron beam. This technology can be used for carbon baseline assessment on regional scale and for monitoring of its surface and depth storage due to the changes in agricultural practices undertaken in order to mitigate global climate change.

Obhodas, Jasmina; Sudac, Davorin; Matjacic, Lidija; Valkovic, Vladivoj

2012-05-01

399

Activated carbon sheet prepared from softwood acetic acid lignin  

Microsoft Academic Search

As an example of activated carbon (AC) moldings, AC sheets were prepared from thermoplastic acetic acid lignin by lamination.\\u000a The resulting AC sheets are a new type of product that can be applied as water and air cleaners. Powdered softwood acetic\\u000a acid lignin (SAL) was molded into sheets by a thermal pressing method. When the sheet was carbonized under a

Yasumitsu Uraki; Ryo Taniwatashi; Satoshi Kubo; Yoshihiro Sano

2000-01-01

400

Production of fungicidal oil and activated carbon from pistachio shell  

Microsoft Academic Search

The main objective of this study was to evaluate the feasibility of pistachio shell as a biomass feedstock for the production of fungicidal oil and a precursor for the production of activated carbon by physical activation. For this purpose, pistachio shell was pyrolyzed in a fixed bed reactor at the different temperatures (300–600°C). The pyrolysis products were identified as gas,

Cagdas Okutucu; Gozde Duman; Suat Ucar; Ihsan Yasa; Jale Yanik

2011-01-01

401

Bioindication Potential of Carbonic Anhydrase Activity in Anemones and Corals  

Microsoft Academic Search

Activity levels of carbonic anhydrase (CA) were assessed in anemones Condylactis gigantea and Stichodactyla helianthus with laboratory exposures to copper, nickel, lead, and vanadium, and also in animals collected from polluted vs pristine field sites. CA activity was found to be decreased with increase in metal concentration and also in animals collected from the polluted field site. Preliminary assessments to

Aubrey L Gilbert; Héctor M Guzmán

2001-01-01

402

Evolution of carbon structure in chemically activated wood  

Microsoft Academic Search

13C NMR and FTIR analyses have been employed to follow the evolution of chemical structure in relation to porosity development, as a function of heat treatment temperature (HTT), for activated carbons produced from white oak by phosphoric acid activation. The chemical changes effected by acid treatment at low HTT are: by 50 °C there is significant alteration of the lignin

M. S. Solum; R. J. Pugmire; M. Jagtoyen; F. Derbyshire

1995-01-01

403

Mechanochemical activation of high-carbon fly ash for enhanced carbon reburning  

Microsoft Academic Search

The focus of the present study is the reduction of the residual unburnt carbon contained in fly ash from PC-fired boilers by reburning and\\/or beneficiation. More specifically, the study addresses the potential of enhancing oxyreactivity of the residual carbon contained in fly ash by mechanochemical activation in order to improve the effectiveness of ash reburning.The concept is tested with reference

Osvalda Senneca; Piero Salatino; Riccardo Chirone; Luciano Cortese; Roberto Solimene

2011-01-01

404

A General Methodology for Evaluation of Carbon Sequestration Activities and Carbon Credits  

SciTech Connect

A general methodology was developed for evaluation of carbon sequestration technologies. In this document, we provide a method that is quantitative, but is structured to give qualitative comparisons despite changes in detailed method parameters, i.e., it does not matter what ''grade'' a sequestration technology gets but a ''better'' technology should receive a better grade. To meet these objectives, we developed and elaborate on the following concepts: (1) All resources used in a sequestration activity should be reviewed by estimating the amount of greenhouse gas emissions for which they historically are responsible. We have done this by introducing a quantifier we term Full-Cycle Carbon Emissions, which is tied to the resource. (2) The future fate of sequestered carbon should be included in technology evaluations. We have addressed this by introducing a variable called Time-adjusted Value of Carbon Sequestration to weigh potential future releases of carbon, escaping the sequestered form. (3) The Figure of Merit of a sequestration technology should address the entire life-cycle of an activity. The figures of merit we have developed relate the investment made (carbon release during the construction phase) to the life-time sequestration capacity of the activity. To account for carbon flows that occur during different times of an activity we incorporate the Time Value of Carbon Flows. The methodology we have developed can be expanded to include financial, social, and long-term environmental aspects of a sequestration technology implementation. It does not rely on global atmospheric modeling efforts but is consistent with these efforts and could be combined with them.

Klasson, KT

2002-12-23

405

Methylene Blue adsorption from aqueous solution by activated carbon: Effect of acidic and alkaline solution treatments  

Microsoft Academic Search

The removal of Methylene Blue (MB) from aqueous solution using activated carbon (AC) has been investigated. Adsorption experiments were conducted and the maximum adsorption capacity was determined. The effect of experimental parameters such as pH, dye concentration and temperature were studied on the adsorption process. Equilibrium data were mathematically modeled using the Langmuir and Freundlich adsorption models to describe the

Christianah O. Ijagbemi; Ji I. Chun; Da. H. Han; Hye Y. Cho; Se J. O; Dong S. Kim

2010-01-01

406

On the equilibrium and dynamic behavior of alcohol vapors in activated carbon  

Microsoft Academic Search

As alcohol molecules such as methanol and ethanol have both polar and non-polar groups, their adsorption behavior is governed by the contributions of dispersion interaction (alkyl group) and hydrogen bonding (OH group). In this paper, the adsorption behavior of alcohol molecules and its effect on transport processes are elucidated. From the total permeability (BT) of alcohol molecules in activated carbon,

Jun-Seok Bae; D. D. Do

2006-01-01

407

Adsorptive removal of aniline by granular activated carbon from aqueous solutions with catechol and resorcinol  

Microsoft Academic Search

In the present paper, the removal of aniline by adsorption process onto granular activated carbon (GAC) is reported from aqueous solutions containing catechol and resorcinol separately. The Taguchi experimental design was applied to study the effect of such parameters as the initial component concentrations (C0, i) of two solutes (aniline and catechol or aniline and resorcinol) in the solution, temperature

S. Suresh; V. C. Srivastava; I. M. Mishra

2012-01-01

408

Zeolite-active carbon compound adsorbent and its use in adsorption solar cooling tube  

Microsoft Academic Search

The “zeolite-water” pair adsorption process has been extensively studied for its application in cooling system. This paper presents a compound zeolite-active carbon adsorbent (CZACA) which enhances the heat transfer in the adsorbent bed by absorbing solar energy directly and decreases the desorption cycle time in a solar cooling system. Experimental study of a special solar cooling tube using this adsorbent

Liu Zhenyan; Lu Yunzhuang; Zhao Jiaxin

1998-01-01

409

Activated carbon: Utilization excluding industrial waste treatment. (Latest citations from the Compendex database). Published Search  

SciTech Connect

The bibliography contains citations concerning the commercial use and theoretical studies of activated carbon. Topics include performance evaluations in water treatment processes, preparation and regeneration techniques, materials recovery, and pore structure studies. Adsorption characteristics for specific materials are discussed. Studies pertaining specifically to industrial waste treatment are excluded. (Contains 250 citations and includes a subject term index and title list.)

Not Available

1993-06-01

410

IRON OPTIMIZATION FOR FENTON-DRIVEN OXIDATION OF MTBE-SPENT GRANULAR ACTIVATED CARBON  

EPA Science Inventory

Fenton-driven chemical regeneration of granular activated carbon (GAC) is accomplished through the addition of H2O2 and iron (Fe) to spent GAC. The overall objective of this treatment process is to transform target contaminants into less toxic byproducts, re-establish the sorpti...

411

Adsorption of the proteins of white wine onto activated carbon, alumina and titanium dioxide  

Microsoft Academic Search

The study investigated the adsorption capacities of bovine serum albumin (BSA), ovalbumin (OVA) and mucin (MUC) onto titanium dioxide, alumina and activated carbon, for the purpose of investigating the optimum conditions of pH and cations concentration of white wine required for the haze removal process. The results showed that the amounts of adsorbed OVA and BSA onto the three adsorbents

Omoniyi Kehinde Israel

2009-01-01

412

Degradation and removal of naphthalenesulphonic acids by means of adsorption and ozonation catalyzed by activated carbon in water  

NASA Astrophysics Data System (ADS)

Studies were conducted on the efficiency of systems based on the use of ozone, activated carbon, and ozone/activated carbon in the treatment of waters containing 1-naphthalenesulphonic acid, 1,5-naphthalenedisulphonic acid, and 1,3,6-naphthalenetrisulphonic acid. In the removal of these acids by adsorption on activated carbon the elevated heights of the mass transfer zone columns and the low values of the breakthrough volumes indicated that a system exclusively based on the use of activated carbon is not appropriate for the removal of these pollutants. In the ozonation of these acids the reactivity of naphthalenesulphonic acid with ozone is low. In addition, the initial concentration of total organic carbon (TOC) was not reduced during naphthalenesulphonic acids ozonation. These results indicate that a system exclusively based on the use of ozone is not adequate to decontaminate water where these acids are present. These ozonation processes were also studied in the presence of activated carbon. The presence of activated carbon enhanced the elimination rate, probably by enhancing ozone decomposition in aqueous phase in highly oxidative species. These catalytic properties seem to be favored by both the basicity of the carbon surface and the higher macropore volume. The catalytic properties of activated carbon were reduced by ozonation. New acid groups such as anhydride, lactones, and carboxylic acid were generated on the activated carbon surface during ozone treatment. This effect reduced the reactivity of the activated carbon to ozone and therefore the capacity to enhance ozone decomposition in aqueous phase. The presence of activated carbon during naphthalenesulphonic acid ozonation produced a reduction in the TOC concentration and in the genotoxicity of the degradation products. All these results indicate that this novel combined system is very promising for the treatment of water polluted with organic matter.

Rivera-Utrilla, J.; SáNchez-Polo, M.

2003-09-01

413

Production of activated carbon and its catalytic application for oxidation of hydrogen sulphide  

NASA Astrophysics Data System (ADS)

Hydrogen sulphide is an environmentally hazardous gas which is present in many gas streams associated with oil and gas industry. Oxidation of H 2S to sulphur in air produces no bulky or waste material and requires no further purification. Activated carbon is known as a catalyst for this reaction. In this research, a coal-based precursor (luscar char) and a biomass-based precursor (biochar) were used for production of activated carbons by two common methods of activation: physical and chemical activation in which steam and potassium hydroxide (KOH), respectively, were used. Experiments were designed by the statistical central composite design method. Two models were developed for the BET surface area and reaction yield of each activation process. These models showed the effects of operating conditions, such as activation temperature, mass ratio of activating agent to precursor, activation time, and nitrogen flowrate on the BET surface area and reaction yield for each activation method for each precursor. The optimum operating conditions were calculated using these models to produce activated carbons with relatively large BET surface area (> 500 m2/g) and high reaction yield (> 50 wt %). The BET surface area and reaction yield for activated carbons produced at optimum operating conditions showed maximum 7 and 7.4% difference, respectively, comparing to the values predicted by models. The activated carbons produced at optimum operating conditions were used as the base catalysts for the direct oxidation of 1 mol % hydrogen sulphide in nitrogen to sulphur at the temperature range of 160-205°C and pressure of 700 kPa. Originally activated carbons showed a good potential for oxidation of hydrogen sulphide by their selectivity for sulphur product and low amount of sulphur dioxide production. To improve the performance of steam-activated carbons, the catalysts were modified by acid-treatment followed by thermal desorption. This method increased the break-through times for coal-based and biomass-based catalysts to 115 and 141 minutes, respectively. The average amounts of sulphur dioxide produced during the reaction time were 0.14 and 0.03% (as % of hydrogen sulphide fed to the reactor) for modified activated carbons prepared from biochar and luscar char, respectively. The effects of porous structure, surface chemistry, and ash content on the performances of these activated carbon catalysts were investigated for the direct oxidation reaction of hydrogen sulphide. The acid-treatment followed by thermal desorption of activated carbons developed the porosity which produced more surface area for active sites and in addition, provided more space for sulphur product storage resulting in higher life time for catalyst. Boehm titration and temperature program desorption showed that the modification method increased basic character of carbon surface after thermal desorption in comparison to acid-treated sample. In addition, the effects of impregnating agents (potassium iodide and manganese nitrate) and two solvents for impregnation process were studied on the performance of the activated carbon catalysts for the direct oxidation of H2S to sulphur. Sulphur L-edge X-ray near edge structure (XANES) showed that the elemental sulphur was the dominant sulphur species in the product. The kinetic study for oxidation reaction of H2S over LusAC-O-D(650) was performed for temperature range of 160-190°C, oxygen to hydrogen sulphide molar ratio of 1-3, and H2S concentration of 6000-10000 ppm at 200 kPa. The values of activation energy were 26.6 and 29.3 kJ.gmol-1 for Eley-Rideal and Langmuir-Hinshelwood mechanisms, respectively.

Azargohar, Ramin

414

Structure and antibacterial activity of silver-supporting activated carbon fibers  

Microsoft Academic Search

In this paper, several kinds of silver supporting activated carbon fibers (ACF-Ag) were prepared by the reduction adsorption\\u000a on activated carbon fiber (ACF) activated with steam or H3PO4 using sisal, viscose and pitch fiber as precursors. Their pore structure and surface chemistry were characterized using nitrogen\\u000a adsorption, XPS, WXRD and ICP quantitative analysis. Their antibacterial activities were tested. The results

Shuixia Chen; Jinrong Liu; Hanmin Zeng

2005-01-01

415

Characteristics of activated carbons prepared from pistachio-nut shells by potassium hydroxide activation  

Microsoft Academic Search

High-surface-area activated carbons in granular form were prepared by chemical activation of pistachio-nut shells with potassium hydroxide. The effects of the preparation variables on the carbon pore structure were studied in order to optimize these parameters. It was found that the chemical to shell impregnation ratio, the activation temperature and the activation hold time were the important parameters that affect

Ting Yang; Aik Chong Lua

2003-01-01

416

Stabilized leachates: ozone-activated carbon treatment and kinetics.  

PubMed

Ozone has been used as a pre-oxidation step for the treatment of stabilized leachates. Given the refractory nature of this type of effluents, the conversion of some wastewater quality parameters has been moderate after 1 h of ozonation (i.e. 30% chemical oxygen demand (COD) depletion). Ozone uptake was calculated in the interval 1.3-1.5 g of ozone per gram of COD degraded. An optimum dose of ozone has been experienced in terms of biodegradability of the processed effluent (60 min of treatment, 1 x 10(-3) mol L(-1) ozone inlet feeding concentration and 50 L h(-1) gas flow-rate). pH and other typical hydroxyl radical generator systems exerted no influence on the efficiency of the process, suggesting the negligible role played by the indirect route of oxidation (generation of hydroxyl radicals). The ozonated effluent was thereafter treated in a second adsorption stage by using a commercial activated carbon. Removal levels up to 90% of COD in approximately 120 h were experienced for adsorbent dosages of 30 g L(-1). Both steps, the single ozonation and the adsorption stage have been modelled by using different pseudoempirical models. PMID:14604628

Rivas, F Javier; Beltrán, Fernando; Gimeno, Olga; Acedo, Benito; Carvalho, Fátima

2003-12-01

417

Novel carbon based catalysts for the reduction of NO: Influence of support precursors and active phase loading  

Microsoft Academic Search

Carbon-supported catalysts in the form of powder, briquettes and monolitos have been prepared. Powder and briquette samples have been obtained using a Spanish low-rank coal as raw material for carbon support through a pyrolysis process whereas monoliths were prepared by coating cordierite monoliths with a blend of two polymers. Vanadium was chosen as active element and impregnated by equilibrium adsorption

M. J. Lázaro; A. Boyano; M. E. Gálvez; M. T. Izquierdo; E. García-Bordejé; C. Ruiz; R. Juan; R. Moliner

2008-01-01

418

Preparation and characterization of activated carbon from a new raw lignocellulosic material: flamboyant (Delonix regia) pods.  

PubMed

Activated carbons were prepared from flamboyant pods by NaOH activation at three different NaOH:char ratios: 1:1 (AC-1), 2:1 (AC-2), and 3:1 (AC-3). The properties of these carbons, including BET surface area, pore volume, pore size distribution, and pore diameter, were characterized from N(2) adsorption isotherms. The activated carbons obtained were essentially microporous and had BET surface area ranging from 303 to 2463 m(2) g(-1).(13)C (CP/MAS and MAS) solid-state NMR shows that the lignocellulosic structures were completely transformed into a polycyclic material after activation process, thermogravimetry shows a high thermal resistance, Boehm titration and Fourier-transform infrared spectroscopy allowed characterizing the presence of functional groups on the surface of activated carbons. Scanning electron microscopy images showed a high pore development. The experimental results indicated the potential use of flamboyant pods as a precursor material in the preparation of activated carbon. PMID:20869158

Vargas, Alexandro M M; Cazetta, André L; Garcia, Clarice A; Moraes, Juliana C G; Nogami, Eurica M; Lenzi, Ervim; Costa, Willian F; Almeida, Vitor C

2010-09-24

419

Chars pyrolyzed from oil palm wastes for activated carbon preparation  

SciTech Connect

Chars pyrolyzed from extracted oil palm fibers for the preparation of activated carbons were studied. The effects of pyrolysis temperature and hold time on density, porosity, yield, BET and micropore surface areas, total pore volume, and pore size distributions of chars were investigated. The optimum conditions for pyrolysis were found to be at a pyrolysis temperature of 850 C for a hold time of 3.5 h. Scanning electron micrographs of the char surfaces verified the presence of porosities. The experimental results showed that it was feasible to produce chars with high BET and micropore surface areas from extracted oil palm fibers. The resulting chars will be subjected to steam or carbon dioxide activation to prepare activated carbons for use as gas adsorbents for air pollution control.

Lua, A.C.; Guo, J. [Nanyang Technological Univ., Singapore (Singapore)

1999-01-01

420

Impact of sulfur oxides on mercury capture by activated carbon  

SciTech Connect

Recent field tests of mercury removal with activated carbon injection (ACI) have revealed that mercury capture is limited in flue gases containing high concentrations of sulfur oxides (SOx). In order to gain a more complete understanding of the impact of SOx on ACI, mercury capture was tested under varying conditions of SO{sub 2} and SO{sub 3} concentrations using a packed bed reactor and simulated flue gas (SFG). The final mercury content of the activated carbons is independent of the SO{sub 2} concentration in the SFG, but the presence of SO{sub 3} inhibits mercury capture even at the lowest concentration tested (20 ppm). The mercury removal capacity decreases as the sulfur content of the used activated carbons increases from 1 to 10%. In one extreme case, an activated carbon with 10% sulfur, prepared by H{sub 2}SO{sub 4} impregnation, shows almost no mercury capacity. The results suggest that mercury and sulfur oxides are in competition for the same binding sites on the carbon surface. 30 refs., 3 figs., 2 tabs.

Albert A. Presto; Evan J. Granite [United States Department of Energy, Pittsburgh, PA (United States). National Energy Technology Laboratory

2007-09-15

421

Carbon Tetrachloride Replacement Compounds for Organic Vapor Air-Purifying Respirator Cartridge and Activated Carbon Testing—A Review  

Microsoft Academic Search

This article reviews efforts by researchers and organizations around the world to identify chemicals as substitutes for carbon tetrachloride in measuring activated carbon activity (adsorption capacity) or organic vapor air-purifying respirator cartridge (or other packed carbon bed) breakthrough times. Such measurements usually are done to determine if a minimum performance standard is met. Different criteria have been established, supporting data

Ernest S. Moyer; Simon J. Smith; Gerry O. Wood

2001-01-01

422

Granular activated carbon for removal of organic matter and turbidity from secondary wastewater.  

PubMed

A range of commercial granular activated carbon (GAC) media have been assessed as pretreatment technologies for a downstream microfiltration (MF) process. Media were assessed on the basis of reduction in both organic matter and turbidity, since these are known to cause fouling in MF membranes. Isotherm adsorption analysis through jar testing with supplementary column trials revealed a wide variation between the different adsorbent materials with regard to organics removal and adsorption kinetics. Comparison with previous work using powdered activated carbon (PAC) revealed that for organic removal above 60% the use of GAC media incurs a significantly lower carbon usage rate than PAC. All GACs tested achieved a minimum of 80% turbidity removal. This combination of turbidity and organic removal suggests that GAC would be expected to provide a significant reduction in fouling of a downstream MF process with improved product water quality. PMID:23306264

Hatt, J W; Germain, E; Judd, S J

2013-01-01

423

Activation of isocyanates and carbon dioxide by a monomeric aluminium hydrazide as an active lewis pair.  

PubMed

The monomeric aluminium hydrazide H10 C5 N?N(AltBu2 )?Ad (4; Ad=adamantyl, NC5 H10 =piperidinyl) was obtained in high yield by hydroalumination of the corresponding hydrazone derivative 1. Compound 4 has a strained AlN2 heterocycle formed by a donor-acceptor bond between the ?-nitrogen atom of the hydrazide group and the aluminium atom. Opening of this bond resulted in the formation of an active Lewis pair that was able to cooperatively activate carbon dioxide or isocyanates. Insertion of the heterocumulenes into the Al?N bond selectively afforded a carbamate and two urea derivatives in high yield. In the first step, phenyl isocyanate gave the adduct 6, which has the oxygen atom coordinated to the aluminium atom and its central carbon atom bound to the nitrogen atom of the piperidine moiety. Adduct 6 represents a reasonable intermediate state for these activation processes. The applicability of hydroaluminated compounds, such as 4, in organic synthesis was demonstrated by the reaction with an imidoyl chloride, which gave the corresponding amidrazone derivative 9. PMID:24038438

Hengesbach, Frank; Jin, Xing; Hepp, Alexander; Wibbeling, Birgit; Würthwein, Ernst-Ulrich; Uhl, Werner

2013-08-27

424

Mechanisms of Activated Carbon Degradation by Perspiration.  

National Technical Information Service (NTIS)

Sweat degradation of activated charcoal was studied by static and dynamic test methods. For the static tests, both untreated and treated charcoal was immersed in a synthetic sweat solution or an aqueous solution of the individual components of the synthet...

L. L. Pytlewski

1977-01-01

425

Sulfur tolerant molten carbonate fuel cell anode and process  

DOEpatents

Molten carbonate fuel cell anodes incorporating a sulfur tolerant carbon monoxide to hydrogen water-gas-shift catalyst provide in situ conversion of carbon monoxide to hydrogen for improved fuel cell operation using fuel gas mixtures of over about 10 volume percent carbon monoxide and up to about 10 ppm hydrogen sulfide.

Remick, Robert J. (Naperville, IL)

1990-01-01

426

PRODUCTION OF CARBON PRODUCTS USING A COAL EXTRACTION PROCESS  

SciTech Connect

The purpose of this DOE-funded effort is to develop technologies for carbon products from coal-derived feed-stocks. Carbon products can include precursor materials such as solvent extracted carbon ore (SECO) and synthetic pitch (Synpitch). In addition, derived products include carbon composites, fibers, foams and others.

Dady Dadyburjor; Chong Chen; Elliot B. Kennel; Liviu Magean; Peter G. Stansberry; Alfred H. Stiller; John W. Zondlo

2005-12-12

427

Complete treatment of olive pomace leachate by coagulation, activated-carbon adsorption and electrochemical oxidation  

Microsoft Academic Search

A battery scheme comprising sequential alum coagulation, activated-carbon adsorption and electrochemical oxidation over boron-doped diamond electrodes to mineralize a leachate from olive pomace processing is demonstrated. The effect of coagulant and adsorbent concentration on treatment efficiency was assessed in the range 0.1–50mM Al3+ and 2.5–50g\\/L activated-carbon and optimal conditions were established. Coagulation at 7.5mM Al3+ resulted in substantial solids and

Michael Mavros; Nikolaos P. Xekoukoulotakis; Dionissios Mantzavinos; Evan Diamadopoulos

2008-01-01

428

Experiments on the generation of activated carbon from biomass  

Microsoft Academic Search

Activated carbon is generated from various waste biomass sources like rice straw, wheat straw, wheat straw pellets, olive stones, pistachios shells, walnut shells, beech wood and hardcoal. After drying the biomass is pyrolysed in the temperature range of 500–600°C at low heating rates of 10K\\/min. The activation of the chars is performed as steam activation at temperatures between 800°C and

Elisabeth Schröder; Klaus Thomauske; Christine Weber; Andreas Hornung; Vander Tumiatti

2007-01-01

429

Activated Carbon Production from Date Stones Using Phosphoric Acid  

Microsoft Academic Search

The effects of activation time and activation temperature on the yield and the adsorptive capacity towards iodine were studied. The yield and the quality of the activated carbon prepared by using H3PO4 were compared with that prepared from date stones using the same equipment, and under similar conditions by using ZnCl2 as an oxidizing agent. The iodine number for the

F. Al-Qaessi; L. Abu-Farah

2010-01-01

430

DEVELOPMENT OF CONTINUOUS SOLVENT EXTRACTION PROCESSES FOR COAL DERIVED CARBON PRODUCTS  

SciTech Connect

The purpose of this DOE-funded effort is to develop continuous processes for solvent extraction of coal for the production of carbon products. These carbon products include materials used in metals smelting, especially in the aluminum and steel industries, as well as porous carbon structural material referred to as ''carbon foam'' and carbon fibers. During this reporting period, efforts have focused on the facility modifications for continuous hydrotreating, as well as developing improved protocols for producing synthetic pitches.

Elliot B. Kennel; Stephen P. Carpenter; Dady Dadyburjor; Manoj Katakdaunde; Liviu Magean; Peter G. Stansberry; Alfred H. Stiller; John W. Zondlo

2005-08-11

431

Reversible Storage of Hydrogen and Natural Gas in Nanospace-Engineered Activated Carbons  

NASA Astrophysics Data System (ADS)

An overview is given of the development of advanced nanoporous carbons as storage materials for natural gas (methane) and molecular hydrogen in on-board fuel tanks for next-generation clean automobiles. High specific surface areas, porosities, and sub-nm/supra-nm pore volumes are quantitatively selected by controlling the degree of carbon consumption and metallic potassium intercalation into the carbon lattice during the activation process. Tunable bimodal pore-size distributions of sub-nm and supra-nm pores are established by subcritical nitrogen adsorption. Optimal pore structures for gravimetric and volumetric gas storage, respectively, are presented. Methane and hydrogen adsorption isotherms up to 250 bar on monolithic and powdered activated carbons are reported and validated, using several gravimetric and volumetric instruments. Current best gravimetric and volumetric storage capacities are: 256 g CH4/kg carbon and 132 g CH4/liter carbon at 293 K and 35 bar; 26, 44, and 107 g H2/kg carbon at 303, 194, and 77 K respectively and 100 bar. Adsorbed film density, specific surface area, and binding energy are analyzed separately using the Clausius-Clapeyron equation, Langmuir model, and lattice gas models.

Romanos, Jimmy; Beckner, Matt; Rash, Tyler; Yu, Ping; Suppes, Galen; Pfeifer, Peter

2012-02-01

432

XPS of nitrogen-containing functional groups on activated carbon  

Microsoft Academic Search

XPS is used to study the binding energy of the Cls, Nls and Ols photoelectrons of surface groups on several nitrogen-containing activated carbons. Specific binding energies are assigned to amide (399.9 eV). lactam and imidc (399.7 eV). pyridine (398.7 eV), pyrrole (400.7 eV), alkylamine. secondary amide and N-alkylimide (399.9 eV) and trialkylaminc (399.7 cV) functional groups on activated carbon. Supporting

R. J. J. Jansen; H. van Bekkum

1995-01-01

433

Removing lead in drinking water with activated carbon  

SciTech Connect

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.

Taylor, R.M.; Kuennen, R.W. (Amway Corp., Ada, MI (United States))

1994-02-01

434

An updated process model for carbon oxidation, nitrification, and denitrification.  

PubMed

The currently available comprehensive activated sludge models, ASM#1 (Grady et al., 1986) and its successor ASM#3 (Gujer et al., 1999), do not adequately describe nitrification and denitrification, with respect to ammonia oxidation inhibition, nitrite accumulation, or emissions of nitric oxide and nitrous oxide. A new comprehensive activated sludge process model, the Activated Sludge Model for Nitrogen (ASMN), is presented. The ASMN incorporates two nitrifying populations-ammonia-oxidizing bacteria and nitrite-oxidizing bacteria-using free ammonia and free nitrous acid, respectively, as their true substrates. The ASMN incorporates four-step denitrification (sequential reduction of nitrate to nitrogen gas via nitrite, nitric oxide, and nitrous oxide) using individual, reaction-specific parameters. Simulation results for ammonia, nitrate, soluble substrate, and biomass concentrations determined by using ASMN for three activated sludge process configurations under steady-state and dynamic municipal-type influent conditions are shown to be comparable with ASM#1 results. PMID:19024730

Hiatt, William C; Grady, C P Leslie

2008-11-01

435

Immobilization of Hg(II) in water with polysulfide-rubber (PSR) polymer-coated activated carbon.  

PubMed

An effective mercury removal method using polymer-coated activated carbon was studied for possible use in water treatment. In order to increase the affinity of activated carbon for mercury, a sulfur-rich compound, polysulfide-rubber (PSR) polymer, was effectively coated onto the activated carbon. The polymer was synthesized by condensation polymerization between sodium tetrasulfide and 1,2-dichloroethane in water. PSR-mercury interactions and Hg-S bonding were elucidated from x-ray photoelectron spectroscopy, and Fourier transform infra-red spectroscopy analyses. The sulfur loading levels were controlled by the polymer dose during the coating process and the total surface area of the activated carbon was maintained for the sulfur loading less than 2 wt%. Sorption kinetic studies showed that PSR-coated activated carbon facilitates fast reaction by providing a greater reactive surface area than PSR alone. High sulfur loading on activated carbon enhanced mercury adsorption contributing to a three orders of magnitude reduction in mercury concentration. ?-X-ray absorption near edge spectroscopic analyses of the mercury bound to activated carbon and to PSR on activated carbon suggests the chemical bond with mercury on the surface is a combination of Hg-Cl and Hg-S interaction. The pH effect on mercury removal and adsorption isotherm results indicate competition between protons and mercury for binding to sulfur at low pH. PMID:20965542

Kim, Eun-Ah; Seyfferth, Angelia L; Fendorf, Scott; Luthy, Richard G

2010-09-21

436

Effects of organic carbon sequestration strategies on soil enzymatic activities  

NASA Astrophysics Data System (ADS)

Greenhouse gases emissions can be counterbalanced with proper agronomical strategies aimed at sequestering carbon in soils. These strategies must be tested not only for their ability in reducing carbon dioxide emissions, but also for their impact on soil quality: enzymatic activities are related to main soil ecological quality, and can be used as early and sensitive indicators of alteration events. Three different strategies for soil carbon sequestration were studied: minimum tillage, protection of biodegradable organic fraction by compost amendment and oxidative polimerization of soil organic matter catalyzed by biometic porfirins. All strategies were compared with a traditional agricultural management based on tillage and mineral fertilization. Experiments were carried out in three Italian soils from different pedo-climatic regions located respectively in Piacenza, Turin and Naples and cultivated with maize or wheat. Soil samples were taken for three consecutive years after harvest and analyzed for their content in phosphates, ß-glucosidase, urease and invertase. An alteration index based on these enzymatic activities levels was applied as well. The biomimetic porfirin application didn't cause changes in enzymatic activities compared to the control at any treatment or location. Enzymatic activities were generally higher in the minimum tillage and compost treatment, while differences between location and date of samplings were limited. Application of the soil alteration index based on enzymatic activities showed that soils treated with compost or subjected to minimum tillage generally have a higher biological quality. The work confirms the environmental sustainability of the carbon sequestering agronomical practices studied.

Puglisi, E.; Suciu, N.; Botteri, L.; Ferrari, T.; Coppolecchia, D.; Trevisan, M.; Piccolo, A.

2009-04-01

437

Reaction engineering for materials processing in space: Reduction of ilmenite by hydrogen and carbon monoxide  

NASA Astrophysics Data System (ADS)

Oxygen is a consumable material which needs to be produced continuously in most space missions. Its use for propulsion as well as life support makes oxygen one of the largest volume chemicals to be produced in space. Production of oxygen from lunar materials is of particular interest and is very attractive possibility. The kinetics and mechanism of reduction of ilmenite by carbon monoxide and hydrogen at 800 to 1100 C were investigated. The temporal profiles of conversion for carbon monoxide have a sigmoidal shape and indicate the presence of three different stages (induction, acceleration, and deceleration) during the reduction reaction. The apparent activation energy decreases from 18 kcal/mole at 10 percent conversion to 10 kcal/mole at 50 percent conversion. The reaction is first order with respect to carbon monoxide under the experimental conditions studied. Both SEM and EDX analysis show that the diffusion of Fe product away from the reaction front and through the TiO2 phase, followed by the nucleation and growth of a separate Fe phase are important steps affecting the process kinetics. The results from hydrogen reduction show that the mechanism of ilmenite reduction by hydrogen is similar to that by carbon monoxide. However, the titanium dioxide can be further reduced by hydrogen at 800 to 1000 C. The detailed comparison and theoretical modeling of both reduction processes is presented.

Zhao, Y.; Shadman, F.

438

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

NASA Astrophysics Data System (ADS)

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 was incorporated with polymelem via a liquid penetration and a CVD method to modify its surface chemistry. The hydrogen adsorption energy of the polymelem doped activated carbon demonstrated a dramatic increase from ˜5 kJ/mol to ˜14 kJ/mol due to the higher polarizability of the polymelem.

Qin, Nan

439

A calcium oxide sorbent process for bulk separation of carbon dioxide  

SciTech Connect

This research effort is designed to investigate the technical feasibility of a high-temperature, high-pressure process for the bulk separation of CO{sub 2} from coal-derived gases. The two-year contract was awarded in September 1989. This report describes the research effort and results obtained during the first year of the effort. The overall project consists of 6 tasks, four of which were active during year 01. Tasks 1 and 2 were completed during the year while activity in Tasks 3 and 6 will carry over into year 02. Tasks 4 and 5 will be initiated during year 02. Three primary objectives were met in Task 1. A literature search on the calcination-carbonation reactions of CO{sub 2} with calcium-based sorbents was completed. A high temperature, high pressure (HTHP) electrobalance reactor suitable for studying the calcination and carbonation reactions was constructed. This reactor system is now fully operable and we are routinely collecting kinetics data at temperatures in the range of 550-900{degree}C and pressures of 1 to 15 atm. Samples of nine candidate calcium-based sorbents were acquired and tested. These samples were subjected to reaction screening tests as part of Task 2. As a result of these screening tests, chemically pure calcium carbonate, chemically pure calcium acetate, and the commercial dolomite were selected for more detailed kinetic testing. In Task 3, the HTHP electrobalance reactor is being used to study the calcination-carbonation behavior of the three base sorbents as a function of calcination temperature, carbonation temperature, carbonation pressure, and CO{sub 2} concentration.

Harrison, D.P.

1990-09-01

440

Processes governing the carbon chemistry during the SAGE experiment  

NASA Astrophysics Data System (ADS)

Measurements of pCO 2, pH and alkalinity in the surface waters of an iron fertilised patch of sub-Antarctic water were made during SAGE (SOLAS SAGE: Surface-Ocean Lower Atmosphere Studies Air-Sea Gas Experiment). The iron addition induced a minor phytoplankton bloom, however the patch dynamics were dominated by physical processes which suppressed and masked the biological effects. The Lagrangian nature of the experiment allowed the carbonate chemistry in the patch to be followed for 15.5 days, and the relative importance of the biological and physical factors influencing the surface water pCO 2 was estimated. The pCO 2 of the surface waters of the patch increased from 327 ?atm prior to iron addition to 338 ?atm on Day 14, effects of vertical and horizontal mixing offset the 15 ?atm drawdown that would have occurred had the induced biological uptake been the sole factor to influence the pCO 2. The air-sea carbon flux calculated using the measured skin temperature and a piston velocity parameterisation determined during SAGE ( Ho et al., 2006) was 98.5% of the flux determined using conventional bulk temperature measurement and the Wanninkhof (1992) piston velocity parameterisation. The skin temperature alone contributed to an 8% increase in the flux compared with that determined using bulk temperature.

Currie, K. I.; Macaskill, B.; Reid, M. R.; Law, C. S.

2011-03-01

441

Purification of Phenolic Wastewater Using Aerobic Biooxidation Combined with Activated Carbon Treatment and Ozonation  

Microsoft Academic Search

The combined process – aerobic bio-oxidation with activated carbon addition and ozonation was studied (ABO\\/AC\\/O3). The performance of the process was compared with conventional aerobic bio-oxidation (ABO). The studies were carried out in two continuous and periodic reactors to evaluate the purification efficiencies (in terms of COD, BOD and resorcinols removal), excess sludge generation and stability of the bioreactors against

Oliver Järvik; Inna Kamenev; Andres Viiroja; Juha Kallas

2010-01-01

442

Comparisons of pore properties and adsorption performance of KOH-activated and steam-activated carbons  

Microsoft Academic Search

Carbonaceous adsorbents with controllable pore sizes derived from carbonized pistachio shells (i.e., char) were prepared by the KOH activation and steam activation methods in this work. The pore properties including the BET surface area, pore volume, pore size distribution, and pore diameter of these activated carbons were characterized by the t-plot method based on N2 adsorption isotherms. Through varying the

Feng-Chin Wu; Ru-Ling Tseng; Chi-Chang Hu

2005-01-01

443

Process and apparatus for further processing of pressurized exothermic reactions. [Up to 6 carbon atoms  

SciTech Connect

A continuous process is described for the carbonylation of ..cap alpha..-olefin having up to six carbon atoms for the preparation of a carboxylic acid or ester thereof and for employing the exothermic heat of the reaction to heat the product mixture for subsequent separation of at least one component from the product mixture. The process consists of: (a) reacting a mixture of carbon monoxide, ..cap alpha..-olefin of up to six carbon atoms, and an acid selected from the group consisting of an aqueous hydrogen fluoride solution of more than 20 weight percent hydrogen fluoride, and a substantially anhydrous acid selected from the group consisting of hydrogen fluoride and hydrogen chloride under pressure and at a low temperature under conditions whereby a product mixture and exothermic heat at pressure up to 10,000 psia and at temperature below about 100/sup 0/ C., (b) reacting the product mixture of step (a) with a hydroxy-containing compound selected from the group consisting of water and an alcohol having up to six carbon atoms under conditions whereby additional exothermic heat is produced and a carboxylic acid is produced when the hydroxy compound is water and under conditions whereby an ester is produced when the hydroxy compound is an alcohol, (c) adiabatically expanding the product mixture of step (a) to below the temperature and pressure of the reaction conditions of step (a), (d) heating the adiabatically expanded product mixture of step (b) with the exothermic heat from reaction of the mixture of the reactants reacting in step (a) by passing the heat to the adiabatically expanded product mixture, and (e) transferring the heated adiabatically expanded product mixture of step (c) to a separation processing step and repeating steps (a), (b), (c), (d), and (e) under conditions whereby a continuous process results.

Pascoe, R.F.

1986-05-20

444

Carbonic anhydrases: novel therapeutic applications for inhibitors and activators  

Microsoft Academic Search

Carbonic anhydrases (CAs), a group of ubiquitously expressed metalloenzymes, are involved in numerous physiological and pathological processes, including gluconeogenesis, lipogenesis, ureagenesis, tumorigenicity and the growth and virulence of various pathogens. In addition to the established role of CA inhibitors (CAIs) as diuretics and antiglaucoma drugs, it has recently emerged that CAIs could have potential as novel anti-obesity, anticancer and anti-infective

Claudiu T. Supuran

2008-01-01

445

Active Teaching with Issues in Ecology: Carbon Dynamics in Ecosystems  

NSDL National Science Digital Library

All ecology texts include figures showing carbon cycles of various types (terrestrial, marine, global, etc). However, education research shows that introductory level students (both college and high school) and many citizens do not understand the biological and ecological processes that are the foundation for these cycles.

D'Avanzo, Charlene

2011-07-20

446

The influence of thermal gradient on pyrocarbon deposition in carbon\\/carbon composites during the CVI process  

Microsoft Academic Search

A thermal gradient CVI process was investigated. A graphite heater in the center of a carbon felt disk preform was heated by Joule heating to a temperature of 900°C, the carbon felt had a low thermal conductivity, and the rapid natural gas flow cooled the exterior surface of the preform. The rate constant of the chemical vapor deposition reaction increased

Jian-guo Zhao; Ke-zhi Li; He-jun Li; Chuang Wang

2006-01-01

447

Dephlegmator process for carbon dioxide-hydrocarbon distillation  

SciTech Connect

This patent describes a process for the separation of a carbonaceous off-gas stream containing a quantity of acid gases, such as carbon dioxide, hydrogen sulfide and carbonyl sulfide, wherein the off-gas stream is compressed, cooled and separated in a low temperature distillation column into a fuel gas stream which is recovered from the top portion of the distillation column, a liquefied acid gas sidestream and a bottoms liquid stream. The improvement comprises: (a) incorporating a dephlegmator as the top portion of the distillation column; (b) passing at least a portion of the liquefied acid gas sidestream to the dephlegmator for indirect heat exchange with distillation column fluids thereby providing refrigeration for the dephlegmator; and (c) subcooling at least a portion of the bottoms liquids stream and passing the subcooled bottoms liquids stream to the dephlegmator for indirect heat exchange with distillation column fluids thereby providing refrigeration for the dephlegmator.

Lucadamo, G.A.; Rowles, H.C.

1988-01-19

448

Capacitive charging and background processes in carbon nanotube yarn actuators  

NASA Astrophysics Data System (ADS)

Twist-spun carbon nanotube yarns actuate when extra charge is added to the yarn. This charge can be stored in a doublelayer capacitor formed when the yarn is submersed in an electrolyte. The dependence of the actuation stress and strain on the stored charge must be studied if double layer charging models are to be fully verified over large potential ranges. However, background currents are generated in the system when an electrical potential is applied, making it hard to discern the charge stored in the actuator and the charge that passes through the cell due to faradaic processes. A model is developed to separate the capacitive and faradaic portions of the actuator current. The model is then applied to the analysis of the actuation data. The consistency of the results paves the way to understanding the real strain-charge behavior of the actuator.

Mirfakhrai, Tissaphern; Kozlov, Mikhail; Zhang, Mei; Fang, Shaoli; Baughman, Ray H.; Madden, John D. W.

2007-04-01

449

Laser ablation process for single-walled carbon nanotube production.  

PubMed

Different types of lasers are now routinely used to prepare single-walled carbon nanotubes. The original method developed by researchers at Rice University used a "double-pulse laser oven" process. Several researchers have used variations of the lasers to include one-laser pulse (green or infrared), different pulse widths (ns to micros as well as continuous wave), and different laser wavelengths (e.g., CO2, or free electron lasers in the near to far infrared). Some of these variations are tried with different combinations and concentrations of metal catalysts, buffer gases (e.g., helium), oven temperatures, flow conditions, and even different porosities of the graphite targets. This article is an attempt to cover all these variations and their relative merits. Possible growth mechanisms under these different conditions will also be discussed. PMID:15296222

Arepalli, Sivaram

2004-04-01

450

Apparatus and process for deposition of hard carbon films  

DOEpatents

A process and an apparatus for depositing thin, amorphous carbon films having extreme hardness on a substrate is described. An enclosed chamber maintained at less than atmospheric pressure houses the substrate and plasma producing elements. A first electrode is comprised of a cavity enclosed within an RF coil which excites the plasma. A substrate located on a second electrode is excited by radio frequency power applied to the substrate. A magnetic field confines the plasma produced by the