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1

Activated carbon from pecan shell: process description and economic analysis  

Microsoft Academic Search

Granular activated carbons derived from pecan shells have been shown to adsorb a variety of metal and organic species in various processing wastewaters. Their effectiveness is equivalent to or exceeds comparable commercial carbons in this regard. The objectives of this study were to develop process flow diagrams for the large-scale production of pecan shell-based carbons derived from steam or phosphoric

Chilton Ng; Wayne E Marshall; Ramu M Rao; Rishipal R Bansode; Jacques N Losso

2003-01-01

2

ACTIVATED CARBON PROCESS FOR TREATMENT OF WASTEWATERS CONTAINING HEXAVALENT CHROMIUM  

EPA Science Inventory

The removal of hexavalent chromium, Cr(VI), from dilute aqueous solution by an activated carbon process has been investigated. Two removal mechanisms were observed; hexavalent chromium species were removed by adsorption onto the interior carbon surface and/or through reduction to...

3

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

PubMed

The characteristics of thermally regenerated activated carbon (AC) polluted with biological activated carbon (BAC) process were investigated. The results showed that the true micropore and sub-micropore volume, pH value, bulk density, and hardness of regenerated AC decreased compared to the virgin AC, but the total pore volume increased. XPS analysis displayed that the ash contents of Al, Si, and Ca in the regenerated AC respectively increased by 3.83%, 2.62% and 1.8%. FTIR spectrum showed that the surface functional groups of virgin and regenerated AC did not change significantly. Pore size distributions indicated that the AC regeneration process resulted in the decrease of micropore and macropore (D>10?m) volume and the increase of mesopore and macropore (0.1?mprocess. PMID:25203235

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

2014-11-01

4

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

5

Carbon activation process for increased surface accessibility in electrochemical capacitors  

DOEpatents

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

Doughty, Daniel H. (Albuquerque, NM); Eisenmann, Erhard T. (Belpre, OH)

2001-01-01

6

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...

7

Dynamic Mass Transfer Process of Activated Carbon Desulfurization on Fixed Bed  

Microsoft Academic Search

Flue gas desulfurization by activated carbon is an environmental-friendly technique used in thermal power plant. The mass transfer process of SO2 about flue gas desulfurization by activated carbon is analyzed, effective mass transfer velocity of SO2 on fixed bed is proposed and mathematics model is established. Internal diffusivity and internal surface availability coefficient of different activated carbons are measured according

Yi Liu; Zidong Cao

2011-01-01

8

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

NASA Technical Reports Server (NTRS)

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

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

1996-01-01

9

Drinking water biotic safety of particles and bacteria attached to fines in activated carbon process  

Microsoft Academic Search

In this paper, the drinking water biotic safety of particles and bacteria attached to fines in activated carbon process was\\u000a investigated by actual treatment process and advanced treatment pilot trial with granular activated carbon. In the experiment,\\u000a the particles were detected by IBR particle calculating instrument, the activated carbon fines were counted on the basis of\\u000a the most probable number

Wei Chen; Tao Lin; Leilei Wang

2007-01-01

10

Production of activated carbon from bamboo scaffolding waste—process design, evaluation and sensitivity analysis  

Microsoft Academic Search

A feasibility study has been carried out on the preliminary process design of the production of activated carbon from the bamboo scaffolding waste based on 30tonnes of bamboo waste per day throughput. A comparison of the process economics of the stand-alone bamboo carbonization plant with a plant that is integrated into another major processing facility has been studied. The preliminary

Keith K. H. Choy; John P. Barford; Gordon McKay

2005-01-01

11

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 128.21 mg g(-1) and carbon content 76.29%, while the BET surface area and total pore volume corresponded to 801.5m(2)g(-1) and 0.393 cm(3)g(-1), respectively. This study demonstrated that high surface area activated carbons can be prepared from the chemical activation of biochar with zinc chloride as activating agents. PMID:24080293

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

2013-11-01

12

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...

13

Process simulation of activated carbon production using a rotary kiln  

Microsoft Academic Search

The rotary kiln used for the activation of charcoal is simulated using mass and energy balances to obtain the temperature\\u000a distributions of environmental gas and solid in the kiln. The computed results are used to find the optimal operation condition.\\u000a In finding the optimal gas temperature for the reductive gas environment necessary to the charcoal activation, the outcome\\u000a gives the

Young Han Kim

2011-01-01

14

Silver recovery from synthetic photographic and medical X-ray process effluents using activated carbon  

Microsoft Academic Search

Adsorption of silver from synthetic photographic and spent fix solutions on granulated activated carbon in a batch process has been investigated. The synthetic solutions prepared had similar properties to medical X-ray and photographic process effluents. Sodium and ammonium thiosulfates are the major lixiviants used in the dissolution of silver halides present in photographic and medical X-ray films. The resultant solutions

K. G. Adani; R. W. Barley; R. D. Pascoe

2005-01-01

15

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

PubMed

A coupling of low-temperature sulfuric acid-assisted carbonization and H3PO4 activation was employed to convert NaOH-pretreated rice husks into activated carbons with extremely high surface area (2028 m(2) g(-1)) and integrated characteristics. The influences of the activation temperature and impregnation ratio on the surface area, pore volume of activated carbons were thoroughly investigated. The morphology and surface chemistry of activated carbons were characterized using N2 sorption, FTIR, XPS, SEM, TEM, etc. The adsorption capacity of resulting carbons obtained under optimum preparation conditions was systematically evaluated using methylene blue under various simulated conditions. The adsorption process can be well described by both Langmuir isotherm model and the pseudo-second order kinetics models; and the maximum monolayer capacity of methylene blue was ca. 578 mg g(-1). PMID:23892148

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

2013-09-01

16

Activated carbon from broiler litter: Process description and cost of production  

Microsoft Academic Search

Animal manure continues to represent a significantly large and problematic portion of the US 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. The objective of this study was to develop a conceptual capital and operating cost estimate using the Superpro Designer process simulation

Isabel M. Lima; Andrew McAloon; Akwasi A. Boateng

2008-01-01

17

Carbon wastewater treatment process  

NASA Technical Reports Server (NTRS)

A new powdered-carbon treatment process is being developed for the elimination of the present problems, associated with the disposal of biologically active sewage waste solids, and with water reuse. This counter-current flow process produces an activated carbon, which is obtained from the pyrolysis of the sewage solids, and utilizes this material to remove the adulterating materials from the water. Additional advantages of the process are the elimination of odors, the removal of heavy metals, and the potential for energy conservation.

Humphrey, M. F.; Simmons, G. M.; Dowler, W. L.

1974-01-01

18

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

PubMed

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

Bae, Wookeun; Kim, Jongho; Chung, Jinwook

2014-08-01

19

Biological activated carbon process for treatment of potato processing wastewater for in-plant reuse. Technical completion report  

SciTech Connect

Like many other food processing industries, potato processing could create a serious pollution problem. An average-sized processing plant, producing french fries and dehydrated potatoes, can generate a waste load equivalent to a city of 200,000 people. Any discharge of wastes into these waters would immediately result in detrimental effects to the environment. In a plant processing 15,000 tons of potatoes per year, 60 million gallons of water are required. With proper treatment, a large percentage of the wastewater could be reclaimed and reused in the potato processing plant. The scope of the study includes the operation of completely mixed activated sludge (CMAS) reactors as secondary treatment, and anaerobic upflow continuous biological activated carbon (BAC) and biological sand columns as tertiary treatment for potato processing wastewaters.

Hung, Y.T.; Priebe, B.D.

1981-10-01

20

Application studies of activated carbon derived from rice husks produced by chemical-thermal process—A review  

Microsoft Academic Search

The production of functional activated carbon materials starting from cheap natural precursors using environmentally friendly processes is a highly attractive subject in material chemistry today. Recently, much attention has been focused on the use of plant biomass to produce functional carbonaceous materials, encompassing economic, environmental and social issues. Besides the classical route to produce activated carbons from fossil materials, rice

Yue Chen; Yanchao Zhu; Zichen Wang; Ying Li; Lili Wang; Lili Ding; Xiaoyan Gao; Yuejia Ma; Yupeng Guo

2011-01-01

21

Manufacturing and environmental applications of granular activated carbon from processed solid residue of olive mill products (JEFT)  

Microsoft Academic Search

A new technique for processing the soild residue of olive mill products (JEFT) to produce granular and powdered activated carbon has been developed. The activation process of JEFT is very cost effective and can be achieved without advanced technology. The manufactured activated carbon has been tested to treat drinking water containing: trace concentrations of Cr(III), Ni(II), Pb(II), Cd(II), and Zn(II);

S. H. Gharaibeh

1999-01-01

22

Dewatering Peat With Activated Carbon  

NASA Technical Reports Server (NTRS)

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

Rohatgi, N. K.

1984-01-01

23

Understanding activated carbons  

SciTech Connect

It would be fair to say that most chemical industry professionals can explain the differences between adsorption and absorption. But when asked which type of activated carbon would be best suited for a particular application, few chemists or chemical engineers would be able to identify what properties to look for. Activated carbon is used in a wide variety of applications such as purification or recovery of chemical products, catalysis or catalyst supports, and various environmental applications such as VPC abatement and wastewater purification. With such broad used in industry, it is critical for engineers and chemists to understand the differences between activated carbons in order to obtain the best performance from their processes.

Boppart, S.; Ingle, L.; Potwora, R.J.; Rester, D.O. [NORIT Americas Inc., Atlanta, GA (United States)

1996-09-01

24

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

2012-07-15

25

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

PubMed

Ozonation was used in this study to improve biodegradability of RO brine from water reclamation facilities. An ozone dosage ranging from 3 to 10 mg O(3)/L and contact times of 10 and 20 min in batch studies were found to increase the biodegradability (BOD(5)/TOC ratio) of the RO brine by 1.8-3.5 times. At the same time, total organic carbon (TOC) removal was in the range of 5.3-24.5%. The lab-scale ozone-biological activated carbon (BAC) at an ozone dosage of 6.0mg O(3)/L with 20-min contact time was able to achieve 3 times higher TOC removal compared to using BAC alone. Further processing with Capacitive Deionization (CDI) process was able to generate a product water with better water quality than the RO feed water, i.e., with more than 80% ions removal and a lower TOC concentration. The ozone-BAC pretreatment has the potential of reducing fouling in the CDI process. PMID:19580984

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

2009-09-01

26

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

EPA Science Inventory

A systematic scanning election microscope analytical technique has been developed to examine granular activated carbon used a a medium for biomass attachment in liquid waste treatment. The procedure allows for the objective monitoring, comparing, and trouble shooting of combined ...

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

Granular activated carbon installations  

Microsoft Academic Search

This article presents a compilation and summary of design criteria, performance, and cost data from 22 operating municipal and industrial granular activated carbon (GAC) installations that treat water and wastewater or process food and beverage products. Guidance for using this information to estimate costs for GAC treatment of water supplies is provided. In conjunction with previous reports, this article may

Russell L. Culp; Robert M. Clark

1983-01-01

29

GRANULAR ACTIVATED CARBON INSTALLATIONS  

EPA Science Inventory

This paper presents a compilation and summary of design criteria, performance, and cost data from 22 operating municipal and industrial granular activated carbon (GAC) installations that treat water and wastewater or process food and beverage products. Guidance for using this inf...

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

Modification process optimization, characterization and adsorption property of granular fir-based activated carbon  

NASA Astrophysics Data System (ADS)

Granular fir-based activated carbon (GFAC) was modified with H2O2, and orthogonal array experimental design method was used to optimize the process. The properties of the original and modified GFAC were characterized by N2 adsorption-desorption isotherms, Brunauer-Emmett-Teller (BET) equation, Barett-Joyner-Halenda (BJH) equation, field emission scanning electron microscopy (FESEM), and Fourier transform infrared spectroscopy (FT-IR) analysis, etc. When 10.00 g of GFAC with particle size of 0.25-0.85 mm was modified by 150.0 ml of aqueous H2O2 solution, the optimized conditions were found to be as follows: aqueous H2O2 solution concentration 1.0 mol·l-1, modification temperature 30.0 °C, modification time 4.0 h. Modified under the optimized conditions, decolonization of caramel, methylene blue adsorption, phenol adsorption and iodine number of the modified GFAC increased by 500.0%, 59.7%, 32.5%, and 15.1%, respectively. The original and optimally modified GFAC exhibited adsorption isotherms of hybrid Type I-IV isotherms with H4 hysteresis. BET surface area, micropore area, total pore volume, micropore volume, and microporosity of the modified GFAC increased by 7.33%, 11.25%, 3.89%, 14.23%, 9.91%, respectively. Whereas the average pore width decreased by 3.16%. In addition, the amount of surface oxygen groups (such as carbonyl or carboxyl) increased in the modified GFAC.

Chen, Congjin; Li, Xin; Tong, Zhangfa; Li, Yue; Li, Mingfei

2014-10-01

32

Minimizing activated carbons production cost  

Microsoft Academic Search

A detailed economic evaluation of activated carbons production process from various raw materials is undertaken using the conventional economic indices (ROI, POT, and NPV). The fundamental factors that affect production cost were taken into account. It is concluded that for an attractive investment in activated carbons production one should select the raw material with the highest product yield, adopt a

G. G. Stavropoulos; A. A. Zabaniotou

2009-01-01

33

Activated carbon from biomass  

NASA Astrophysics Data System (ADS)

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

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

2013-06-01

34

Process optimization of preparation of ZnO-porous carbon composite from spent catalysts using one step activation.  

PubMed

The process parameters of one step preparation of ZnO/Activated Carbon (AC) composite materials, from vinyl acetate synthesis spent catalyst were optimized using response surface methodology (RSM) and the central composite rotatable design (CCD). Regeneration temperature, time and flow rate of CO2 were the process variables, while the iodine number and the yield were the response variables. All the three process variables were found to significantly influence the yield of the regenerated carbon, while only the regeneration temperature and CO2 flow rate were found to significantly affect the iodine number. The optimized process conditions that maximize the yield and iodine adsorption capacity were identified to be a regeneration temperature of 950 degrees C, time of 120 min and flow rate of CO2 of 600 ml/min, with the corresponding yield and iodine number to be in excess of 50% and 1100 mg/g. The BET surface area of the regenerated composite was estimated to be 1263 m2/g, with micropore to mesopore ratio of 0.75. The pore volume was found to have increased 6 times as compared to the spent catalyst. The composite material (AC/ZnO) with high surface area and pore volume coupled with high yield augur economic feasibility of the process. EDS and XRD spectrum indicate presence of ZnO in the regenerated samples. PMID:22962730

Jin, Wen; Qu, Wen-Wen; Srinivasakannan, C; Peng, Jin-Hui; Duan, Xin-Hui; Zhang, Shi-Min

2012-08-01

35

Two kinds of composite films: Graphene oxide/carbon nanotube film and graphene oxide/activated carbon film via a self-assemble preparation process  

NASA Astrophysics Data System (ADS)

Two kinds of free-standing composite films, including graphene oxide and activated carbon film as well as graphene oxide and carbon nanotube film, were fabricated through a simple suspension mixing and then natural deposition process. The films were characterized by various measurement techniques in detail. The results show that the composite films without any treatment almost still remain the original properties of the corresponding precursors, and exhibit loose structure, which can be easily broken in water; whereas after treated at 200 °C in air, the films become relatively more dense, and even if immersed into concentrated strong alkali or acid for five days, they still keep the film-morphologies, but regretfully, they show obvious brittleness and slight hydrophilicity. As soon as the treated films are performed in high concentrated strong alkali for about one day, their brittleness and wettability can be improved and became good flexibility and complete hydrophilicity.

Zou, Li-feng; Ma, Nan; Sun, Mei; Ji, Tian-hao

2014-11-01

36

ZnCl2Modified Activated Carbon from Biomass Coir Pith for the Removal of 2Chlorophenol by Adsorption Process  

Microsoft Academic Search

Coir pith, a waste biomass, from coconut coir industry was used to prepare activated carbon with ZnCl2 and employed for the removal of 2-chlorophenol (2-CP) from aqueous solution and wastewater. Zinc chloride–activated coir pith carbon (ZnCPC) was prepared by mixing coir pith with ZnCl2 in the ratio 2:1 and carbonized at 700°C for 1 h. ZnCPC was characterized using standard

R. Subha; C. Namasivayam

2010-01-01

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

Activated carbon gets revved up  

SciTech Connect

When it comes to adsorption, few products can match the low cost and efficient performance of activated carbon. That`s why the material is so widely used for wastewater treatment. But with processors looking for economical ways to achieve environmental compliance in other operations, the market s taking off in different directions, wit much attention focused on air purification, process water treatment and solvent recovery. It is the opportunity that manufacturers and marketers of activated carbon have been waiting for. All revved up, they are generating new products and regenerating spent carbon, and rounding out their offerings with equipment and technical service. The article discusses new products and applications, increasing regeneration capacity, and competition in the activated carbon industry.

Hairston, D.

1995-11-01

39

Increased removal capacity for 1,2-dichloroethane by biological modification of the granular activated carbon process.  

PubMed

The removal of 5 mg l-1 1,2-dichloroethane [(CH2Cl)2] was studied in two granular activated carbon (GAC) reactors run with hydraulic retention times of below 1 h. One reactor was operated abiotically. The other one was inoculated with microorganisms able to degrade (CH2Cl)2. While the (CH2Cl)2-adsorption capacity of the non-inoculated GAC reactor was exhausted after 20 days, it apparently did not exhaust for at least 170 experimental days in the biologically activated system because (CH2Cl)2 was removed to over 95% as a result of the microbial degradation. The biodegradation was quantified: during the passage through the biologically activated GAC reactor, (CH2Cl)2 (5 +/- 1 mg l-1) disappeared, chloride ions (3.3 +/- 0.2 mg l-1) were produced, and oxygen (4 to 6 mg l-1) was consumed. Removal of 30% of GAC at the entrance of the reactor, which visibly carried most of the biomass, and its replacement by virgin GAC at the end of the column did not change the apparent (CH2Cl)2 removal capacity of the GAC column, indicating that still enough biomass was available to degrade most of the chemical fed. After the addition of the virgin carbon, the effluent concentration fell for a short period of time from about 200 micrograms l-1 to below 100 micrograms l-1, indicating partial adsorption of the non-degraded (CH2Cl)2 at the end of the reactor by the virgin carbon. Thus, the modification of the adsorption process by inoculation and maintenance of bacteria with special degradation capabilities resulted in a lower consumption of GAC and thus led to an extended service life of the GAC columns. PMID:7765815

Stucki, G; Thüer, M

1994-10-01

40

Protein Immobilization on Carbon Nanotubes Via a Two-Step Process of Diimide-Activated Amidation  

Microsoft Academic Search

Carbon nanotubes exhibit interesting electrical, structural and mechanical properties that make them highly promising nanoscale building blocks for the construction of novel functional materials. Many potential applications have been proposed, such as conductive and high-strength composites, field emission displays, fuel cells, sensors, and hydrogen storage media. In addition, biosensors for detecting abnormalities and bio-fuel cells for embedded devices are among

Kuiyang Jiang; Linda S. Schadler; Richard W. Siegel; Xinjie Zhang; Haifeng Zhang; Mauricio Terrones

2004-01-01

41

[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

42

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

43

Activated carbon gets revved up  

Microsoft Academic Search

When it comes to adsorption, few products can match the low cost and efficient performance of activated carbon. That`s why the material is so widely used for wastewater treatment. But with processors looking for economical ways to achieve environmental compliance in other operations, the market s taking off in different directions, wit much attention focused on air purification, process water

1995-01-01

44

Continuous process preparation of activated silica with low carbon dioxide content gas  

E-print Network

of equipment operation which gave an activated product should. be accurate enough to cause activation in different, but similar equipment. Operating conditions found. 8o /0 /0 Figure ~ /oo /00o /moog C e/ Time, //oorq Gel Time oF Activated Sols Based... of equipment operation which gave an activated product should. be accurate enough to cause activation in different, but similar equipment. Operating conditions found. 8o /0 /0 Figure ~ /oo /00o /moog C e/ Time, //oorq Gel Time oF Activated Sols Based...

Burdett, Joseph Walton

2012-06-07

45

Applicability of the biological activated carbon process to the tertiary treatment of refinery wastewater for reuse purposes  

SciTech Connect

It is generally accepted that the Clean Water Act (1977) gave an impetus to the reuse of wastewater. Recycling of cooling water has always received considerable attention by refineries because it represents as much as 90% of refinery water usage. It has been shown that to minimize makeup water (and thus increase recycling), either the evaporation rate and/or the blowdown must be reduced. This can be accomplished by minimizing the amount of contaminants added to the system, or in other words, improve the quality of the makeup water. The biological activated carbon (BAC) process was tested as an advanced treatment technology for the production of a reusable effluent of a high quality in terms of organic matter.

Schwartz, M. (Jacobs Engineering Group, Inc., Pasadena, CA); James, L.S.; Rice, R.G.; Benedek, A.

1982-01-01

46

SIMULTANEOUS MECHANICAL AND HEAT ACTIVATION: A NEW ROUTE TO ENHANCE SERPENTINE CARBONATION REACTIVITY AND LOWER CO2 MINERAL SEQUESTRATION PROCESS COST  

SciTech Connect

Coal can support a large fraction of global energy demands for centuries to come, if the environmental problems associated with CO{sub 2} emissions can be overcome. Unlike other candidate technologies, which propose long-term storage (e.g., ocean and geological sequestration), mineral sequestration permanently disposes of CO{sub 2} as geologically stable mineral carbonates. Only benign, naturally occurring materials are formed, eliminating long-term storage and liability issues. Serpentine carbonation is a leading mineral sequestration process candidate, which offers large scale, permanent sequestration. Deposits exceed those needed to carbonate all the CO{sub 2} that could be generated from global coal reserves, and mining and milling costs are reasonable ({approx}$4 to $5/ton). Carbonation is exothermic, providing exciting low-cost process potential. The remaining goal is to develop an economically viable process. An essential step in this development is increasing the carbonation reaction rate and degree of completion, without substantially impacting other process costs. Recently, the Albany Research Center (ARC) has accelerated serpentine carbonation, which occurs naturally over geological time, to near completion in less than an hour. While reaction rates for natural serpentine have been found to be too slow for practical application, both heat and mechanical (attrition grinding) pretreatment were found to substantially enhance carbonation reactivity. Unfortunately, these processes are too energy intensive to be cost-effective in their present form. In this project we explored the potential that utilizing power plant waste heat (e.g., available up to {approx}200-250 C) during mechanical activation (i.e., thermomechanical activation) offers to enhance serpentine mineral carbonation, while reducing pretreatment energy consumption and process cost. This project was carried out in collaboration with the Albany Research Center (ARC) to maximize the insight into the potential thermomechanical activation offers. Lizardite was selected as the model serpentine material for investigation, due to the relative structural simplicity of its lamellar structure when compared with the corrugated and spiral structures of antigorite and chrysotile, respectively. Hot-ground materials were prepared as a function of grinding temperature, time, and intensity. Carbonation reactivity was explored using the standard ARC serpentine carbonation test (155 C, 150 atm CO{sub 2}, and 1 hr). The product feedstock and carbonation materials were investigated via a battery of techniques, including X-ray powder diffraction, electron microscopy, thermogravimetric and differential thermal, BET, elemental, and infrared analysis. The incorporation of low-level heat with moderate mechanical activation (i.e., thermomechanical activation) was found to be able to substantially enhance serpentine carbonation reactivity in comparison with moderate mechanical activation alone. Increases in the extent of carbonation of over 70% have been observed in this feasibility study, indicating thermomechanical activation offers substantial potential to lower process cost. Investigations of the thermomechanically activated materials that formed indicate adding low-level heat during moderately intense lizardite mechanical activation promotes (1) energy absorption during activation, (2) structural disorder, and (3) dehydroxylation, as well as carbonation reactivity, with the level of energy absorption, structural disorder and dehydroxylation generally increasing with increasing activation temperature. Increasing activation temperatures were also associated with decreasing surface areas and water absorptive capacities for the activated product materials. The above decreases in surface area and water absorption capacity can be directly correlated with enhanced particle sintering during thermomechanical activation, as evidenced by electron microscopy observation. The level of induced structural disorder appears to be a key parameter in enhancing carbonation reactivity. However, p

M.J. McKelvy; J. Diefenbacher; R. Nunez; R.W. Carpenter; A.V.G. Chizmeshya

2005-01-01

47

Chemical Analysis and Process Classification of Constituents of Effluents (Organic Nitrogen in Activated Carbon Effluents.  

National Technical Information Service (NTIS)

The purpose of the research discussed in this report was to characterize by process response and chemical analysis the residual organic constituents in waters, especially the nitrogen-bearing components of wastewater treatment effluents following biologic...

T. B. Helfgott

1975-01-01

48

Adsorption characteristics of malachite green on activated carbon derived from rice husks produced by chemical-thermal process.  

PubMed

Phosphoric acid (H(3)PO(4)) and sodium hydroxide (NaOH) treated rice husks, followed by carbonization in a flowing nitrogen were used to study the adsorption of malachite green (MG) in aqueous solution. The effect of adsorption on contact time, concentration of MG and adsorbent dosage of the samples treated or carbonized at different temperatures were investigated. The results reveal that the optimum carbonization temperature is 500 degrees C in order to obtain adsorption capacity that is comparable to the commercial activated carbon for the husks treated by H(3)PO(4). It is interesting to note that MG adsorbed preferably on carbon-rich than on silica rich-sites. It is found that the behaviour of H(3)PO(4) treated absorbent followed both the Langmuir and Freundlich models while NaOH treated best fitted to only the Langmuir model. PMID:15978990

Rahman, I A; Saad, B; Shaidan, S; Sya Rizal, E S

2005-09-01

49

Paracrystalline structure of activated carbons  

NASA Astrophysics Data System (ADS)

Structural studies by means of neutron diffraction of activated carbons, prepared from a polymer of phenol formaldehyde resin by carbonization and activation processes, with variable porosity, are presented. The neutron scattering data were recorded over the range of the scattering vector Q from 2.5 to 500 nm-1. The structure of activated carbons has been described in terms of disordered graphite-like layers with very weak interlayer correlations. The model has been generated by computer simulations and its validity has been tested by comparison of the experimental and calculated intensity functions. Modelling studies have shown that the model containing 3-4 layers each about 2 nm in diameter accounts for the experimental data and that graphite layers are randomly translated and rotated, according to the turbostratic structure. Near-neighbour carbon-carbon distances of about 0.139 nm and 0.154 nm have been determined. The Debye-Waller factor exp (-Q2?2/2) with ? = ?0(r)1/2 suggests a paracrystalline structure within a single layer. The value of the interlayer spacing of 0.36 nm has been found from paracrystalline simulations of the layer arrangement in the c-axis direction. The high quality of the experimental data has enabled determination of the coordination numbers, the interatomic distances and their standard deviations using a curve-fitting procedure over the Q-range from 250 nm to 500 nm, providing structural information about short- and intermediate-range ordering.

Szczygielska, A.; Burian, A.; Dore, J. C.

2001-06-01

50

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

51

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

52

Making Activated Carbon by Wet Pressurized Pyrolysis  

NASA Technical Reports Server (NTRS)

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

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

2006-01-01

53

Increased removal capacity for 1,2-dichloroethane by biological modification of the granular activated carbon process  

Microsoft Academic Search

The removal of 5 mg 1-1 1,2-dichloroethane [(CH2Cl)2] was studied in two granular activated carbon (GAC) reactors run with hydraulic retention times of below 1 h. One reactor was operated abiotically. The other one was inoculated with microorganisms able to degrade (CH2Cl)2. While the (CH2Cl)2-adsorption capacity of the non-inoculated GAC reactor was exhausted after 20 days, it apparently did not

G. Stucki; M. Thiier

1994-01-01

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.] [Univ. of Roorkee (India). Chemistry Dept.

1997-06-01

55

Removal efficiency of anionic and nonionic surfactants from chemical wastewater by a treatment plant using activated carbon adsorption and coagulation precipitation processes  

Microsoft Academic Search

Removal efficiency of anionic (Sodium n?Dodecylbenzenesulfonate) and nonionic (Heptaoxyethylene Dodecyl Ether) surfactants from chemical wastewater by a treatment plant using activated carbon adsorption and coagulation precipitation processes was investigated. The results showed that anionic and nonionic surfactants were removed from the wastewater by the treatment with.the respective average removal efficiency of 67.4 % and 31.7 %. However, our experiments showed

Atsuko Adachi; Michiyo Kamide; Reiko Kawafune; Naoko Miki; Tadashi Kobayashi

1990-01-01

56

The preparation of active carbons from coal by chemical and physical activation  

Microsoft Academic Search

A series of activated carbons was prepared from bituminous coal by chemical activation with potassium hydroxide and zinc chloride and also by physical activation with carbon dioxide. The effect of process variables such as carbonization time, temperature, particle size, chemical agents, method of mixing and impregnation ratio in the chemical activation process was studied in order to optimize those preparation

A. Ahmadpour; D. D. Do

1996-01-01

57

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

58

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...

59

Biochar as a precursor of activated carbon.  

PubMed

Biochar was evaluated as a precursor of activated carbon. This product was produced by chemical activation using potassium hydroxide. The effects of operating conditions of activation process, such as temperature, activating agent to biochar mass ratio, and nitrogen flow rate, on the textural and chemical properties of the product were investigated. Activated carbon produced by this method has internal surface area at least 50 times than that of the precursor and is highly microporous, which is also confirmed by scanning electron microscopy analysis. Fourier-transform infrared spectroscopy analysis showed development of aromatization in the structure of activated carbon. X-ray diffraction data indicated the formation of small, two-dimensional graphite-like structure at high temperatures. Thermogravimetric study showed that when potassium hydroxide to biochar mass ratio was more than one, the weight loss decreased. PMID:16915686

Azargohar, R; Dalai, A K

2006-01-01

60

Biochar as a precursor of activated carbon.  

PubMed

Biochar was evaluated as a precursor of activated carbon. This product was produced by chemical activation using potassium hydroxide. The effects of operating conditions of activation process, such as temperature, activating agent to biochar mass ratio, and nitrogen flow rate, on the textural and chemical properties of the product were investigated. Activated carbon produced by this method has internal surface area at least 50 times than that of the precursor and is highly microporous, which is also confirmed by scanning electron microscopy analysis. Fourier-transform infrared spectroscopy analysis showed development of aromatization in the structure of activated carbon. X-ray diffraction data indicated the formation of small, two-dimensional graphite-like structure at high temperatures. Thermogravimetric study showed that when potassium hydroxide to biochar mass ratio was more than one, the weight loss decreased. PMID:18563652

Azargohar, R; Dalai, A K

2006-03-01

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

Process of making carbon-carbon composites  

NASA Technical Reports Server (NTRS)

A carbon composite structure, for example, an automotive engine piston, is made by preparing a matrix including of a mixture of non crystalline carbon particulate soluble in an organic solvent and a binder that has a liquid phase. The non crystalline particulate also contains residual carbon hydrogen bonding. An uncured structure is formed by combining the matrix mixture, for example, carbon fibers such as graphite dispersed in the mixture and/or graphite cloth imbedded in the mixture. The uncured structure is cured by pyrolyzing it in an inert atmosphere such as argon. Advantageously, the graphite reinforcement material is whiskered prior to combining it with the matrix mixture by a novel method involving passing a gaseous metal suboxide over the graphite surface.

Withers, James C. (Inventor); Loutfy, Raouf O. (Inventor); Kowbel, Witold (Inventor); Bruce, Calvin (Inventor); Vaidyanathan, Ranji (Inventor)

2000-01-01

63

Competitive Carbon-Sulfur vs Carbon-Carbon Bond Activation of 2-Cyanothiophene with [Ni(dippe)H]2  

E-print Network

Competitive Carbon-Sulfur vs Carbon-Carbon Bond Activation of 2-Cyanothiophene with [Ni(dippe)H]2 Hydrodesulfurization (HDS) is the process by which sulfur is removed from hydrocarbons during the refinement of petroleum. Failure to remove sulfur during this process results in the formation of noxious sulfur oxides

Jones, William D.

64

Modification of activated carbon with different agents and catalytic performance of products obtained in the process of ethylbenzene dehydrogenation coupled with nitrobenzene hydrogenation  

Microsoft Academic Search

Coupling of oxidative dehydrogenation of ethylbenzene with nitrobenzene hydrogenation (ODE-N), over activated carbons catalysts, has been investigated. Activated carbon was prepared from cherry stones and modified with different chemical agents in the liquid phase (HNO3, CH3COOOH, H2O2, (NH4)2S2O8) or gas phase (air, hydrogen, ammonia) or was subjected to thermal treatment to obtain materials with different surface properties. The initial carbon

Anna Malaika; Mieczys?aw Koz?owski

2011-01-01

65

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...

66

Effects of process parameters on hydrothermal carbonization  

NASA Astrophysics Data System (ADS)

In recent years there has been increased research activity in renewable energy, especially upgrading widely available lignicellulosic biomass, in a bid to counter the increasing environmental concerns related with the use of fossil fuels. Hydrothermal carbonization (HTC), also known as wet torrefaction or hot water pretreatment, is a process for pretreatment of diverse lignocellulosic biomass feedstocks, where biomass is treated under subcritical water conditions in short contact time to produce high-value products. The products of this process are: a solid mass characterized as biochar/biocoal/biocarbon, which is homogeneous, energy dense, and hydrophobic; a liquid stream composed of five and six carbon sugars, various organic acids, and 5-HMF; and a gaseous stream, mainly CO2. A number of process parameters are considered important for the extensive application of the HTC process. Primarily, reaction temperature determines the characteristics of the products. In the solid product, the oxygen carbon ratio decreases with increasing reaction temperature and as a result, HTC biochar has the similar characteristics to low rank coal. However, liquid and gaseous stream compositions are largely correlated with the residence time. Biomass particle size can also limit the reaction kinetics due to the mass transfer effect. Recycling of process water can help to minimize the utility consumption and reduce the waste treatment cost as a result of less environmental impact. Loblolly pine was treated in hot compressed water at 200 °C, 230 °C, and 260 °C with 5:1 water:biomass mass ratio to investigate the effects of process parameters on HTC. The solid product were characterized by their mass yields, higher heating values (HHV), and equilibrium moisture content (EMC), while the liquid were characterized by their total organic carbon content and pH value.

Uddin, Md. Helal

67

PRODUCTION OF ACTIVATED CARBON FROM SAWDUST USING FLUIDIZED BED REACTOR  

Microsoft Academic Search

ABSTARCT Activated carbon was produced from sawdust by using steam activation in a high temperature muffle furnace. Fast pyrolysis process was carried out prior in fluidized a bed furnace to produce char before activation process. Experiments were conducted to investigate the influence of various process parameters such as particle size, pyrolysis temperature and activation time on the quality of the

MAN KEE LAM; RIDZUAN ZAKARIA

68

Hydrocarbon recovery with activated carbon  

Microsoft Academic Search

The principle of adsorption has been used extensively to remove water and to recover gasoline from natural gas with gel-type adsorbents in the quick cycle plants. With the gel adsorbents, water will be adsorbed and will actually replace any hydrocarbons being held by the adsorbent. However, with activated carbon, only heavier organic compounds will replace the lighter ones. The recently

Enneking

1968-01-01

69

Adsorption of basic dyes from aqueous solution onto activated carbons  

Microsoft Academic Search

The aim of this research is to compare the adsorption capacity of different types of activated carbons produced by steam activation in small laboratory scale and large industrial scale processes. Equilibrium behaviour of the activated carbons was investigated by performing batch adsorption experiments using bottle-point method. Basic dyes (methylene blue (MB), basic red (BR) and basic yellow (BY)) were used

Emad N. El Qada; Stephen J. Allen; Gavin M. Walker

2008-01-01

70

Mechanistic Investigation of Catalytic Carbon-Carbon Bond Activation and Formation by Platinum and Palladium Phosphine  

E-print Network

Mechanistic Investigation of Catalytic Carbon-Carbon Bond Activation and Formation by Platinum). The breaking of C-C bonds is also crucial in coal liquefaction processes such as the Exxon Donor Solvent process or the Microcat Coal Liquefaction process. Presently cracking is achieved with heterogeneous

Jones, William D.

71

Evaluation of solution-processable carbon-based electrodes for all-carbon solar cells.  

PubMed

Carbon allotropes possess unique and interesting physical, chemical, and electronic properties that make them attractive for next-generation electronic devices and solar cells. In this report, we describe our efforts into the fabrication of the first reported all-carbon solar cell in which all components (the anode, active layer, and cathode) are carbon based. First, we evaluate the active layer, on standard electrodes, which is composed of a bilayer of polymer sorted semiconducting single-walled carbon nanotubes and C(60). This carbon-based active layer with a standard indium tin oxide anode and metallic cathode has a maximum power conversion efficiency of 0.46% under AM1.5 Sun illumination. Next, we describe our efforts in replacing the electrodes with carbon-based electrodes, to demonstrate the first all-carbon solar cell, and discuss the remaining challenges associated with this process. PMID:23113673

Ramuz, Marc P; Vosgueritchian, Michael; Wei, Peng; Wang, Chenggong; Gao, Yongli; Wu, Yingpeng; Chen, Yongsheng; Bao, Zhenan

2012-11-27

72

Enhanced carbon monoxide utilization in methanation process  

DOEpatents

Carbon monoxide - containing gas streams are passed over a catalyst to deposit a surface layer of active surface carbon thereon essentially without the formation of inactive coke. The active carbon is subsequently reacted with steam or hydrogen to form methane. Surprisingly, hydrogen and water vapor present in the feed gas do not adversely affect CO utilization significantly, and such hydrogen actually results in a significant increase in CO utilization.

Elek, Louis F. (Peekskill, NY); Frost, Albert C. (Congers, NY)

1984-01-01

73

Treatment of azo dye-containing wastewater by a Fenton-like process in a continuous packed-bed reactor filled with activated carbon.  

PubMed

In this work, oxidation with a Fenton-like process of a dye solution was carried out in a packed-bed reactor. Activated carbon Norit RX 3 Extra was impregnated with ferrous sulfate and used as catalyst (7 wt.% of iron). The effect of the main operating conditions in the Chicago Sky Blue (CSB) degradation was analyzed. It was found that the increase in temperature leads to a higher removal of the dye and an increased mineralization. However, it also increases the iron leaching, but the values observed were below 0.4 ppm (thus, far below European Union limits). It was possible to reach, at steady-state, a dye conversion of 88%, with a total organic carbon (TOC) removal of ca. 47%, being the reactor operated at 50°C, pH 3, W(cat)/Q=4.1 g min mL(-1) (W(cat) is the mass of catalyst and Q the total feed flow rate) and a H(2)O(2) feed concentration of 2.25 mM (for a CSB feed concentration of 0.012 mM). The same performance was reached in three consecutive cycles. PMID:22964388

Mesquita, Isabel; Matos, Luís C; Duarte, Filipa; Maldonado-Hódar, F J; Mendes, Adélio; Madeira, Luis M

2012-10-30

74

Production and characterization of granular activated carbon from activated sludge  

Microsoft Academic Search

In this study, activated sludge was used as a precursor to prepare activated carbon using sulfuric acid as a chemical activation agent. The effect of preparation conditions on the produced activated carbon characteristics as an adsorbent was investigated. The results indicate that the produced activated carbon has a highly porous structure and a specific surface area of 580 m 2

Z. Al-Qodah; R. Shawabkah

2009-01-01

75

Preparation and characterization of activated carbon foam from phenolic resin.  

PubMed

Activated carbon foam was successfully prepared from phenolic resin synthesized with phenol and formaldehyde under alkali condition. The influence of process variables, such as steam rate, carbonization temperature, carbonization time, activation temperature and activation time on the adsorption capacities of the activated carbon foam was studied. Under the optimum experimental conditions, the activated carbon foam with a specific surface area 727.62 m(2)/g was obtained. Moreover, the iodine value and carbon tetrachloride value of the activated carbon foam was 1050.28 mg/g and 401.37 mg/g, respectively. The pore size of the activated carbon foam was in the range of 3.5-5 nm which was determined through the N2 adsorption test. In addition, the yield of the activated carbon foam was 36.24%. The result of scanning electron microscopy (SEM) showed that the activated carbon foam became honeycomb structure, and its pore wall was thinner and smoother compared to the unactivated carbon foam. PMID:25084407

Zhao, Xuefei; Lai, Shiquan; Liu, Hongzha; Gao, Lijuan

2009-01-01

76

Making Activated Carbon for Storing Gas  

NASA Technical Reports Server (NTRS)

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

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

2005-01-01

77

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

2013-03-01

78

Effect of granular activated carbon addition on the effluent properties and fouling potentials of membrane-coupled expanded granular sludge bed process.  

PubMed

To mitigate membrane fouling of membrane-coupled anaerobic process, granular activated carbon (GAC: 50g/L) was added into an expanded granular sludge bed (EGSB). A short-term ultrafiltration test was investigated for analyzing membrane fouling potential and underlying fouling mechanisms. The results showed that adding GAC into the EGSB not only improved the COD removal efficiency, but also alleviated membrane fouling efficiently because GAC could help to reduce soluble microbial products, polysaccharides and proteins by 26.8%, 27.8% and 24.7%, respectively, compared with the control system. Furthermore, excitation emission matrix (EEM) fluorescence spectroscopy analysis revealed that GAC addition mainly reduced tryptophan protein-like, aromatic protein-like and fulvic-like substances. In addition, the resistance distribution analysis demonstrated that adding GAC primarily decreased the cake layer resistance by 53.5%. The classic filtration mode analysis showed that cake filtration was the major fouling mechanism for membrane-coupled EGSB process regardless of the GAC addition. PMID:25203232

Ding, An; Liang, Heng; Qu, Fangshu; Bai, Langming; Li, Guibai; Ngo, Huu Hao; Guo, Wenshan

2014-11-01

79

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

80

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

2013-01-01

81

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

82

DEVELOPMENT OF ACTIVATED CARBONS FROM COAL COMBUSTION BY-PRODUCTS  

SciTech Connect

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

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

2003-09-30

83

Carbon sources and biogeochemical processes in Monticchio maar lakes, Mt Vulture volcano (southern Italy): New geochemical constrains of active degassing of mantle derived fluids  

NASA Astrophysics Data System (ADS)

Since the catastrophic releases of carbon dioxide from the African volcanic lakes Nyos and Monoun in the 1980s, the scientific community draw attention towards all those crater lakes able to accumulate massive amount of CO2, which could be catastrophically released following overturn of their deep waters. This implies a quantification of the gas accumulation rate into the lakes and the knowledge of recharge processes and their evolution in time. In fact the gaseous recharge in a lake occurs at alarming rates, when an active degassing of hazardous nature volatiles occurs into the lakes and the structure and dynamic of the lake permit the accumulation of gases into the water. The Monticchio lakes, LPM and LGM, occupies two maar craters formed during the last volcanic activity of Mt. Vulture occurred ˜ 140 000 years ago. LPM is a permanently stratified lake, with a thick deep volume of stagnant water and a shallower layer affected by seasonal overturn. On the contrary LGM is a monomittic lake with a complete overturn of the water during winter time. The major dissolved volatiles are methane and CO2. Dissolved helium is in trace amounts and its isotopic signature ranges between 6.1 and 5.3 Ra (Ra is the atmospheric 3He/4He isotopic ratio). These values are within the range of those measured in the olivine fluid inclusions (both of mantle xenoliths and dispersed in the pyroclastics) of LPM maar ejecta. During three years of investigations we observed that dissolved methane in the deep waters of LGM drastically decreases in wintertime as consequence of the complete overturn of the water. The isotopic signature of methane in the deepest portions of LGM (both sediment and water) is quite stable with time and highlights a biogenic origin, being produced both by acetate fermentation and by CO2-reduction in variable proportions. In contrast, a higher contribution of methane produced via CO2 reduction characterizes sediments at shallower depths. At LPM, there is a great difference in methane contents between shallower (< 14m) and deep water, being CH4 concentrations higher in the stagnant volume of waters. Nonetheless the large gradient in methane contents (CH4 increases with depth) observed in the deep waters both C and H isotopes of methane remain constant with depth. In contrast, in the shallow waters the changes in dissolved CH4 contents are accompanied with modifications in the isotope signature of methane thus indicating that oxidation processes seem to be relevant only at a depth lower than 14 m. It is striking that in this lake, CO2-reduction is thought to be the main methanogenesis pathway for methane dissolved in the waters, while in the sediments methane is mainly produced by acetate fermentation. As methanogenesis processes leads to both bacterial consumption and production of CO2, the quantification of these becomes fundamental in inferring the nature and the quantitative releasing of carbon dioxide of magmatic origin and estimation of its isotopic signature. The re-calculated isotopic compositions (-7 ‰< ^13C<-1 ‰) fall within typically magmatic values, furthermore they fall also in the range of Mt. Vulture carbonatites. The computed values of C/3He (2-8 x 109) are in the range of sub-continental mantle. As the Monticchio lakes can be view as natural geological reservoirs subjected to injection of bio and a-biogenic gases, this study shows that amounts and isotopic signature of methane coupled to total dissolved inorganic carbon is a sensitive tool to evaluate the amount of mantle-derived fluids carried into groundwater feeding the lakes.

Caracausi, A.; Nuccio, P. M.; Favara, R.; Grassa, F.

2012-04-01

84

JPL Activated Carbon Treatment System (ACTS) for sewage  

NASA Technical Reports Server (NTRS)

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

1976-01-01

85

Adsorption of herbicides using activated carbons  

SciTech Connect

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

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

1996-10-01

86

Purification of Graphite used in Carbon Activation  

NASA Astrophysics Data System (ADS)

Carbon Activation has been developed as a diagnostic to determine the yield of tertiary neutrons. However, copious primary neutrons easily activate positron-emitting contaminants within the disks. To reduce contaminant levels, a thorough purification process has been developed. Detailed packaging and handling procedures are being perfected in order to minimize the gamma signal produced by contaminants. A vacuum oven was used to heat the graphite disks to 1000¢XC @ 200 microns for varying time intervals. The bakeout drove contaminants such as nitrogen, oxygen and hydrocarbons from the disks, which in turn has greatly reduced the number of gamma counts. Careful hermetic packaging procedures have been developed so that the disks do not come in contact with air or other surface contaminants after the bakeout. These techniques have been refined, significantly reducing the contamination signal seen on high-neutron-yield shots on OMEGA. The experimental results of contamination measurements in carbon samples performed in 2001¡V2002 will be presented, as well as the feasibility of implementing a carbon activation system at the National Ignition Facility. Research funded in part by the United States Department of Energy.

Voltz, Katie; Padalino, Stephen; Bamugart, Leigh; Jiang, Hui Ming; Smith, Elizabeth; Colburn, Robyn; Fuschino, Julia

2002-10-01

87

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

88

Process for producing improved carbon blacks  

SciTech Connect

This paper describes a process for producing carbon black in a reactor vessel utilizing combustion gases and feedstock oil. It comprises: supplying a linear, substantially non-swirling flow of combustion gases into a feedstock oil injection zone in the reactor, supplying at least two independently controlled streams of carbon black feedstock oil into separate segments of the flow of combustion gases in the feedstock oil injection zone wherein separate carbon black forming reactions are respectively effected in separate segments of the flow of combustion gases, and immediately thereafter supplying the combustion gas segments in which the separate carbon black forming reactions have been effected into an aggregate-forming zone whereby a carbon black product is produced which, when compounded in rubber compositions, provides the rubber compositions with improved hysteresis loss and treadwear resistance properties.

Norman, D.T.; Marney, G.L.

1991-01-29

89

Activated carbon fiber composite material and method of making  

DOEpatents

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

Burchell, Timothy D. (Oak Ridge, TN); Weaver, Charles E. (Knoxville, TN); Chilcoat, Bill R. (Knoxville, TN); Derbyshire, Frank (Lexington, KY); Jagtoyen, Marit (Lexington, KY)

2001-01-01

90

Activated carbon fiber composite material and method of making  

DOEpatents

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

Burchell, Timothy D. (Oak Ridge, TN); Weaver, Charles E. (Knoxville, TN); Chilcoat, Bill R. (Knoxville, TN); Derbyshire, Frank (Lexington, KY); Jagtoyen, Marit (Lexington, KY)

2000-01-01

91

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 first year progress in exploring a novel approach that offers the potential to substantially enhance carbonation reactivity while bypassing pretreatment activation. 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{sup +}, Na{sup +}, K{sup +}, Rb{sup +}, Cl{sup -}, 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. Synergistic control of these parameters offers the potential for further improvements in carbonation reactivity. A new sonication exfoliation system incorporating a novel sealing system was developed to carry out the sonication studies. Our initial studies that incorporate controlled sonication have not yet lead to a significant improvement in the extent of carbonation observed. Year 2 studies will emphasize those approaches that offer the greatest potential to cost effectively enhance carbonation, as well as combined approaches that may further enhance carbonation. Mechanistic investigations indicate incongruent dissolution results in the observed silica-rich passivating layer formation. Observations of magnesite nanocrystals within the passivating layers that form indicate the layers can exhibit significant permeability to the key reactants present (e.g., Mg{sup 2+}, H{sup +}, H{sub 2}O, CO{sub 2}, and HCO{sub 3} -). Atomistic modeling supports the observation of robust passivating layers that retain significant permeability to the key reaction species involved. Studies in Year 2 will emphasize the impact that controlled aqueous speciation and activity and slurry-flow dynamics have on the mechanisms that control carbonation reactivity and the potential they offer to substantially reduce olivine mineral sequestration process cost.

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

2005-10-01

92

Purification process for vertically aligned carbon nanofibers  

NASA Technical Reports Server (NTRS)

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.

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

2003-01-01

93

Synthesis of optimal adsorptive carbon capture processes.  

SciTech Connect

Solid sorbent carbon capture systems have the potential to require significantly lower regeneration energy compared to aqueous monoethanol amine (MEA) systems. To date, the majority of work on solid sorbents has focused on developing the sorbent materials themselves. In order to advance these technologies, it is necessary to design systems that can exploit the full potential and unique characteristics of these materials. The Department of Energy (DOE) recently initiated the Carbon Capture Simulation Initiative (CCSI) to develop computational tools to accelerate the commercialization of carbon capture technology. Solid sorbents is the first Industry Challenge Problem considered under this initiative. An early goal of the initiative is to demonstrate a superstructure-based framework to synthesize an optimal solid sorbent carbon capture process. For a given solid sorbent, there are a number of potential reactors and reactor configurations consisting of various fluidized bed reactors, moving bed reactors, and fixed bed reactors. Detailed process models for these reactors have been modeled using Aspen Custom Modeler; however, such models are computationally intractable for large optimization-based process synthesis. Thus, in order to facilitate the use of these models for process synthesis, we have developed an approach for generating simple algebraic surrogate models that can be used in an optimization formulation. This presentation will describe the superstructure formulation which uses these surrogate models to choose among various process alternatives and will describe the resulting optimal process configuration.

chang, Y.; Cozad, A.; Kim, H.; Lee, A.; Vouzis, P.; Konda, M.; Simon, A.; Sahinidis, N.; Miller, D.

2011-01-01

94

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

95

Characterization and application of activated carbon produced from oak cups pulp  

Microsoft Academic Search

Activated carbons have been prepared from a lignocellulosic waste material by chemical activation. Phosphoric acid and zinc chloride have been used as activating agent. The influence of process variables on the carbons’ surface area was studied to optimize these parameters. The textural properties of active carbons were characterized by N2 adsorption at 77K and SEM analysis, while Boehm titration and

Serkan Timur; Ismail Cem Kantarli; Sermin Onenc; Jale Yanik

2010-01-01

96

Selecting activated carbon for water and wastewater treatability studies  

SciTech Connect

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

Zhang, W.; Chang, Q.G.; Liu, W.D.; Li, B.J.; Jiang, W.X.; Fu, L.J.; Ying, W.C. [East China University of Chemical Technology, Shanghai (China)

2007-10-15

97

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-Martín, M. L.; González-García, C. M.; González, J. F.; Ramiro, A.; Sabio, E.; Bruque, J. M.; Encinar, J. M.

2002-05-01

98

Tertiary activated carbon treatment of paper and board industry wastewater  

Microsoft Academic Search

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

Hardy Temmink; Katja Grolle

2005-01-01

99

Catalytic Growth of Macroscopic Carbon Nanofibers Bodies with Activated Carbon  

NASA Astrophysics Data System (ADS)

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

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

2009-06-01

100

Chemical activation of gasification carbon residue for phosphate removal  

NASA Astrophysics Data System (ADS)

Recycling of waste materials provides an economical and environmentally significant method to reduce the amount of waste. Bioash formed in the gasification process possesses a notable amount of unburned carbon and therefore it can be called a carbon residue. After chemical activation carbon residue could be use to replace activated carbon for example in wastewater purification processes. The effect of chemical activation process variables such as chemical agents and contact time in the chemical activation process were investigated. This study also explored the effectiveness of the chemically activated carbon residue for the removal of phosphate from an aqueous solution. The experimental adsorption study was performed in a batch reactor and the influence of adsorption time, initial phosphate concentration and pH was studied. Due to the carbon residue's low cost and high adsorption capacity, this type of waste has the potential to be utilised for the cost-effective removal of phosphate from wastewaters. Potential adsorbents could be prepared from these carbonaceous by-products and used as an adsorbent for phosphate removal.

Kilpimaa, Sari; Runtti, Hanna; Lassi, Ulla; Kuokkanen, Toivo

2012-05-01

101

Machining process and superficial hardness of carbon-carbon composites  

SciTech Connect

The aim of this work is to present some experiment`s results concerning with the machinability and the determination of the superficial hardness of green carbon fiber reinforced phenolic workpieces, and three different kinds of carbon fiber reinforced carbon (CRFC) samples. Firstly, this work shows a characterization of the CFRC composite related with its composition, fabrication process, mechanical properties and main applications. Secondly, two kinds of hardness were measured: (1) Rockwell, L and (2) Micro Vickers. More than 200 indentations were carried out. In the main, the results of the Rockwell L tests showed better repeatability than those based on the Micro Vickers tests. After the hardness test, a comparative analysis of the CRFC composite machinability is done about the green carbon fiber reinforced phenolic composites. Experimental of turning were carried out to study the performance of different tool materials. Experimental results showed that only diamond tools are suitable for use in finish turning. In rough turning, the cemented carbide tools showed to be the best solution. This work ends with suggestions of machining parameters for CRFC composites, allowing some basic cutting conditions to be established for the turning operations.

Coppini, N.L.; Ferreira, J.R. [Univ. of Campinas, Sao Paulo (Brazil). Dept. of Manufacturing Engineering; Neto, F.L.; Freitas, A.C.; Pardini, L.C. [Aerospace Technical Centre, Sao Jose dos Campos, Sao Paulo (Brazil). Inst. of Aeronautic and Space

1996-12-01

102

Reprocessing of used tires into activated carbon and other products  

SciTech Connect

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 (> 800 m{sup 2}/g solid product) were produced in relatively high yields by pyrolysis of tires at up to 900 C, followed by activation in CO{sub 2} at the same temperature. The surface areas of these materials are comparable with those of commercial activated carbons. The efficiency of the activation process (gain in specific surface area/loss in mass) was greatest (up to 138 m{sup 2}/g original tire) when large pieces of tire material were used ({approximately} 170 mg). Oxygen pretreatment of tires was found to enhance both the yield and the surface area of the carbon product. High-pressure treatment of tires at low temperatures (< 400 C) is an alternative approach if the recovery of carbon black or fuel oils is the primary objective.

Teng, H.; Serio, M.A.; Wojtowicz, M.A.; Bassilakis, R.; Solomon, P.R. [Advanced Fuel Research, Inc., East Hartford, CT (United States)

1995-09-01

103

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

104

Combination of adsorption and biodegradation processes for textile effluent treatment using a granular activated carbon-biofilm configured packed column system.  

PubMed

The objective of this study was to investigate the feasibility of using a granular activated carbon-biofilm configured packed column system in the decolorization of azo dye Acid Orange 7-containing wastewater. The Acid Orange 7-degrading microbial from anaerobic sequencing batch reactor which treating the azo dye-containing wastewater for more than 200 d was immobilized on spent granular activated carbon (GAC) through attachment. The GAC-biofilm configured packed column system showed the ability to decolorize 100% of the azo dye when working at high loading rate of Acid Orange 7 at 2.1 g/(L x d) with treatment time of 24 h. It was observed that the decolorization rate increased along with the increasing of initial Acid Orange 7 concentrations, until it reached an optimum point at about 0.38 g/h with initial Acid Orange 7 concentrations of 1,150 mg/L and the decolorization rate tend to be declined beyond this concentration. PMID:18817074

Ong, SoonAn; Toorisaka, Eiichi; Hirata, Makoto; Hano, Tadashi

2008-01-01

105

ACTIVATED CARBON FOR PRECIOUS METALS RECOVERY  

Microsoft Academic Search

Guidelines are presented for the selection, handling and regeneration of activated carbon used in gold recovery operations. The guidelines are based on Calgon Carbon Corporation's own investigations and experience gained in working with gold mine operators all over the world. Gold adsorption rate and adsorption capacity are shown to be independent variables thereby requiring testing of both properties when selecting

William D. Faulkner; John E. Urbanic; Robert W. Ruckel

106

Activated carbons and double layer capacitance  

Microsoft Academic Search

The porous structures and electrochemical double layer capacitance of activated carbon microbeads and carbon fibers were investigated using nitrogen gas adsorption and electrochemical constant current cycling (CCC) methods. Porous structural information on pore size distribution (PSD) and surface area were extracted through a gas adsorption analysis program based on density functional theory (DFT). The relation between the porous surface areas

Hang Shi

1996-01-01

107

Production and characterization of activated carbons from cereal grains  

SciTech Connect

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

Venkatraman, A.; Walawender, W.P.; Fan, L.T. [Kansas State Univ., Manhattan, KS (United States)

1996-12-31

108

Preparation and characteristics of agricultural waste activated carbon by physical activation having micro- and mesopores  

Microsoft Academic Search

Micro–mesoporous activated carbons were prepared from various agricultural wastes by physical activation. Agricultural wastes such as macadamia nut-shell, corncob, bagasse bottom ash, sawdust fly ash and rice husk fly ash, were optimized and processed to obtain the highest surface area. The effects of the amount of volatile matter in char, the activating agent, the activating temperature and kind of raw

Amphol Aworn; Paitip Thiravetyan; Woranan Nakbanpote

2008-01-01

109

78 FR 13894 - Certain Activated Carbon From China  

Federal Register 2010, 2011, 2012, 2013

...731-TA-1103 (Review)] Certain Activated Carbon From China Determination On...antidumping duty order on certain activated carbon from China would be likely to...February 2013), entitled Certain Activated Carbon from China: Investigation...

2013-03-01

110

Activated carbons from steam exploded wood  

SciTech Connect

Earlier work has focused on synthesis of activated carbons from hardwood-white oak and yellow poplar. Current studies have been aimed at understanding the role of biopolymer composition and structure on the porosity development in activated carbons. To this end, wood and wood fractions have been produced by steam explosion and extraction methods to provide starting materials with a range of different compositional characteristics. Powdered activated carbons have been synthesized from these precursors by phosphoric acid activation. The pore size distribution of the activated carbons is highly dependent upon the starting material, it varies with steam explosion conditions (ie, severity) as well as with fractionation protocol. Unfractionated steam exploded fibers produce carbons with different pore size distribution than those that have been extracted with water or alkali. The results suggest that there may be good possibilities for producing carbons with controlled porosity through blending appropriate fractions - hence broadening the range of applications for wood carbons. Studies are also under way to examine the ability to form high surface area extrudates from the wood fractions and their blends.

Jagtoyen, M.; Derbyshire, F.; Wright, R.S. [Univ. of Kentucky Center for Applied Energy Research, Lexington, KY (United States)] [and others

1995-12-01

111

Gas Adsorption by Activated and Impregnated Carbons.  

National Technical Information Service (NTIS)

HCN/H2O mixed vapor isotherms were measured on BPL activated and ASC whetlerite carbons maintaining an essentially constant relative water pressure and varying the relative HCN pressure. Chemisorption data on ASC whetlerite showed water vapor retention va...

G. B. Freeman, P. J. Reucroft

1977-01-01

112

ACTIVATED CARBON ADSORPTION OF TRACE ORGANIC COMPOUNDS  

EPA Science Inventory

Research was conducted to determine how effectively humic substances and the trace contaminants 2-methylisoborneol (MIB), geosmin, the chlorophenols and polynuclear aromatic hydrocarbons were adsorbed by activated carbon under the competitive adsorption conditions encountered in ...

113

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

114

Activated Carbons From Grape Seeds By Chemical Activation With Potassium Carbonate And Potassium Hydroxide  

NASA Astrophysics Data System (ADS)

Activated carbons were produced from grape seed using either potassium carbonate (K2CO3) or potassium hydroxide (KOH). The carbonization experiments were accomplished at 600 and 800 °C. The effects of the experimental conditions (i.e., type of activation reagents, reagent concentrations, and carbonization temperatures) on the yields and the properties of these activated carbons were analyzed under identical conditions. An increase in the temperature at the same concentrations for both K2CO3 and KOH led to a decrease in the yields of the activated carbons. The lowest activated carbon yields were obtained at 800 °C at the highest reagent concentration (100 wt%) for both K2CO3 and KOH. The activated carbon with the highest surface area of 1238 m2g-1 was obtained at 800 °C in K2CO3 concentration of 50 wt% while KOH produced the activated carbon with the highest surface area of 1222 m2g-1 in a concentration of 25wt% at 800 °C. The obtained activated carbons were mainly microporous.

Okman, Irem; Karagöz, Selhan; Tay, Turgay; Erdem, Murat

2014-02-01

115

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

116

Carbon activation diagnostic for tertiary neutron measurements  

NASA Astrophysics Data System (ADS)

The yield of tertiary neutrons with energies greater than 20 MeV has been proposed to determine the high ?R of inertial confinement fusion targets. The activation of carbon is a valuable measurement technique because of its high reaction threshold, the availability of high-purity samples, and relatively low cost. The 12C(n,2n)11C reaction has a Q value of 18.7 MeV, well above the 14.1 MeV primary DT neutron energy. The isotope 11C decays with a half-life of 20.3 min and emits a positron, resulting in the production of two back-to-back, 511 keV gamma rays upon annihilation. The positron decay of 11C is nearly identical to the copper decay used in the activation measurements of 14.1 MeV primary DT yields; therefore, the present copper activation gamma-detection system can be used to detect the tertiary-produced carbon activation. Because the tertiary neutron yield is more than six orders of magnitude lower than primary neutron yield, the carbon activation diagnostic requires ultrapure carbon samples, free from any positron-emitting contamination. In recent years we have developed carbon purification, packaging, and handling procedures that minimize the contamination signal to a level low enough to use carbon activation for tertiary neutron measurements in direct-drive implosion experiments with DT cryogenic targets on OMEGA. Experimental results of contamination measurements in carbon samples performed on high-neutron-yield shots on OMEGA in 2001-2002 will be presented. A concept for implementing a carbon activation system on the National Ignition Facility (NIF) will be discussed.

Glebov, V. Yu.; Stoeckl, C.; Sangster, T. C.; Meyerhofer, D. D.; Radha, P. B.; Padalino, S.; Baumgart, L.; Colburn, R.; Fuschino, J.

2003-03-01

117

Bromate removal during transition from new granular activated carbon (GAC) to biological activated carbon (BAC)  

Microsoft Academic Search

Bromate removal by activated carbon after ozonation is a subject of concern, since bromate is commonly found in the ozonation of bromide-containing water. Though new GAC (granular activated carbon) shows the capacity to reduce bromate to bromide, in the long-term use of GAC following ozonation, its bromate removal rate apparently decreases during transition from new GAC to BAC (biological activated

Mari Asami; Takako Aizawa; Takayuki Morioka; Wataru Nishijima; Akihisa Tabata; Yasumoto Magara

1999-01-01

118

Carbonation: An Efficient and Economical Process for CO2 Sequestration  

E-print Network

Carbonation: An Efficient and Economical Process for CO2 Sequestration Tarun R Naik1 and Rakesh sequestration. Most of the studies related to the carbonation are limited to its effects on corrosion. The possibility of using carbonation process as a direct means for carbon dioxide sequestration is yet

Wisconsin-Milwaukee, University of

119

JV Task 90 - Activated Carbon Production from North Dakota Lignite  

SciTech Connect

The Energy & Environmental Research Center (EERC) has pursued a research program for producing activated carbon from North Dakota lignite that can be competitive with commercial-grade activated carbon. As part of this effort, small-scale production of activated carbon was produced from Fort Union lignite. A conceptual design of a commercial activated carbon production plant was drawn, and a market assessment was performed to determine likely revenue streams for the produced carbon. Activated carbon was produced from lignite coal in both laboratory-scale fixed-bed reactors and in a small pilot-scale rotary kiln. The EERC was successfully able to upgrade the laboratory-scale activated carbon production system to a pilot-scale rotary kiln system. The activated carbon produced from North Dakota lignite was superior to commercial grade DARCO{reg_sign} FGD and Rheinbraun's HOK activated coke product with respect to iodine number. The iodine number of North Dakota lignite-derived activated carbon was between 600 and 800 mg I{sub 2}/g, whereas the iodine number of DARCO FGD was between 500 and 600 mg I{sub 2}/g, and the iodine number of Rheinbraun's HOK activated coke product was around 275 mg I{sub 2}/g. The EERC performed both bench-scale and pilot-scale mercury capture tests using the activated carbon made under various optimization process conditions. For comparison, the mercury capture capability of commercial DARCO FGD was also tested. The lab-scale apparatus is a thin fixed-bed mercury-screening system, which has been used by the EERC for many mercury capture screen tests. The pilot-scale systems included two combustion units, both equipped with an electrostatic precipitator (ESP). Activated carbons were also tested in a slipstream baghouse at a Texas power plant. The results indicated that the activated carbon produced from North Dakota lignite coal is capable of removing mercury from flue gas. The tests showed that activated carbon with the greatest iodine number was superior to commercial DARCO FGD for mercury capture. The results of the activated carbon market assessment indicate an existing market for water treatment and an emerging application for mercury control. That market will involve both existing and new coal-fired plants. It is expected that 20% of the existing coal-fired plants will implement activated carbon injection by 2015, representing about 200,000 tons of annual demand. The potential annual demand by new plants is even greater. In the mercury control market, two characteristics are going to dominate the customer's buying habit-performance and price. As continued demonstration testing of activated carbon injection at the various coal-fired power plants progresses, the importance of fuel type and plant configuration on the type of activated carbon best suited is being identified.

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

2008-03-31

120

Activated carbons derived from oil palm empty-fruit bunches: Application to environmental problems  

Microsoft Academic Search

Activated carbons derived from oil palm empty fruit bunches (EFB) were investigated to find the suitability of its application for removal of phenol in aqueous solution through adsorption process. Two types of activation namely; thermal activation at 300, 500 and 800°C and physical activation at 150°C (boiling treatment) were used for the production of the activated carbons. A control (untreated

Suleyman A. MUYIBI; Mariatul F. MANSOR; Radziah WAHID

2007-01-01

121

Carbon Nanotube Integration with a CMOS Process  

PubMed Central

This work shows the integration of a sensor based on carbon nanotubes using CMOS technology. A chip sensor (CS) was designed and manufactured using a 0.30 ?m CMOS process, leaving a free window on the passivation layer that allowed the deposition of SWCNTs over the electrodes. We successfully investigated with the CS the effect of humidity and temperature on the electrical transport properties of SWCNTs. The possibility of a large scale integration of SWCNTs with CMOS process opens a new route in the design of more efficient, low cost sensors with high reproducibility in their manufacture. PMID:22319330

Perez, Maximiliano S.; Lerner, Betiana; Resasco, Daniel E.; Pareja Obregon, Pablo D.; Julian, Pedro M.; Mandolesi, Pablo S.; Buffa, Fabian A.; Boselli, Alfredo; Lamagna, Alberto

2010-01-01

122

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

2012-09-01

123

Activated Carbon and Carbon Black Catalyzed Transformation of Aqueous Ozone into OH-Radicals  

Microsoft Academic Search

In an ozone-containing water a suspension of a few milligrams per liter of activated carbon (AQ or carbon black (CB) initiates a radical-type chain reaction that then proceeds in the aqueous phase and accelerates the transformation of O3 into secondary radicals, such as hydroxyl radicals (°OH). This results in an Advanced Oxidation Process (AOP) that is similar to an O3-based

Urs Jans; Jürg Hoigné

1998-01-01

124

The Carbon Cycle and its Role in Climate Change: Activity 3  

NSDL National Science Digital Library

In this activity, learners explore the human influences on the carbon cycle and examine how fossil fuels release carbon. Learners role play as miners, power plant operators, car drivers, and home owners in a city. Learners will act out how each member of society contributes to the carbon cycle and then create a classroom mural depicting the path of carbon. Learners can reflect on this process as well as brainstorm ways to lower their carbon footprints. This activity is the third in a series of three activities that introduce learners to the carbon cycle (see related sources), although it is not mandatory that all three activities are completed as a set.

Management, Us B.; Agency, Us E.; Service, Us F.; Service, Us F.; Administration, National A.; Administration, National A.

2009-01-01

125

Optical Properties of the Carbon-Modified TiO2 Prepared by Microwave Carbonization Process  

NASA Astrophysics Data System (ADS)

The carbon-modified TiO2 were synthesized through microwave carbonization of ethanol by using a domestic microwave oven. This process enabled to form the carbonaceous compounds on the surface of TiO2 and created several new mid-gap bands into the original bandgap within few minutes operation. The sample showed a remarkable visible-light absorption even at the wavelength of around 800 nm. The promotion of photocatalytic activity under visible and ultraviolet (UV) light irradiation were also confirmed by the I3- formation in KI aqueous solution. The I3- formation rate of carbon-modified TiO2 per unit mass under visible light is almost 25 times higher than that of pure TiO2. The mid-gap optical absorption mechanisms were investigated through analysis of absorption edges. It is revealed that surface state change against microwave-treatment time results in different mid-gap optical absorption processes.

Sonobe, Taro; Jitputti, Jaturong; Hachiya, Kan; Mitani, Tomohiko; Shinohara, Naoki; Yoshikawa, Susumu

2008-11-01

126

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

127

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...

128

PYROGENIC ACTIVITY OF CARBON-FILTERED WATERS  

EPA Science Inventory

The endotoxin content and pyrogenic response of granular activated carbon (GAC) filtered waters were studied. GAC-filtered secondary effluent from an activated sludge pilot plant contained free endotoxins in the range 6-250 micrograms/l yielding positive pyrogenic responses in 18...

129

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

130

Process for making hollow carbon spheres  

DOEpatents

A hollow carbon sphere having a carbon shell and an inner core is disclosed. The hollow carbon sphere has a total volume that is equal to a volume of the carbon shell plus an inner free volume within the carbon shell. The inner free volume is at least 25% of the total volume. In some instances, a nominal diameter of the hollow carbon sphere is between 10 and 180 nanometers.

Luhrs, Claudia C.; Phillips, Jonathan; Richard, Monique N.; Knapp, Angela Michelle

2013-04-16

131

A novel activated carbon for supercapacitors  

SciTech Connect

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

Shen, Haijie [Key Laboratory of Environmentally Friendly Chemistry and Applications of Ministry of Education, College of Chemistry, Xiangtan University, Hunan 411105 (China)] [Key Laboratory of Environmentally Friendly Chemistry and Applications of Ministry of Education, College of Chemistry, Xiangtan University, Hunan 411105 (China); Liu, Enhui, E-mail: liuenhui99@sina.com.cn [Key Laboratory of Environmentally Friendly Chemistry and Applications of Ministry of Education, College of Chemistry, Xiangtan University, Hunan 411105 (China)] [Key Laboratory of Environmentally Friendly Chemistry and Applications of Ministry of Education, College of Chemistry, Xiangtan University, Hunan 411105 (China); Xiang, Xiaoxia; Huang, Zhengzheng; Tian, Yingying; Wu, Yuhu; Wu, Zhilian; Xie, Hui [Key Laboratory of Environmentally Friendly Chemistry and Applications of Ministry of Education, College of Chemistry, Xiangtan University, Hunan 411105 (China)] [Key Laboratory of Environmentally Friendly Chemistry and Applications of Ministry of Education, College of Chemistry, Xiangtan University, Hunan 411105 (China)

2012-03-15

132

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

133

SUPERCRITICAL FLUID REGENERATION OF ACTIVATED CARBON FOR ADSORPTION OF PESTICIDES  

EPA Science Inventory

The report describes the development of a new process for regenerating activated carbon, using supercritical CO2 as a desorbent. Supercritical CO2 in the range of 30-250 C and at pressures > 80 atm. is a good solvent for organics. A series of pesticides was tested for treatment b...

134

Production Scale-Up or Activated Carbons for Ultracapacitors  

SciTech Connect

Transportation use accounts for 67% of the petroleum consumption in the US. Electric and hybrid vehicles are promising technologies for decreasing our dependence on petroleum, and this is the objective of the FreedomCAR & Vehicle Technologies Program. Inexpensive and efficient energy storage devices are needed for electric and hybrid vehicle to be economically viable, and ultracapacitors are a leading energy storage technology being investigated by the FreedomCAR program. The most important parameter in determining the power and energy density of a carbon-based ultracapacitor is the amount of surface area accessible to the electrolyte, which is primarily determined by the pore size distribution. The major problems with current carbons are that their pore size distribution is not optimized for liquid electrolytes and the best carbons are very expensive. TDA Research, Inc. (TDA) has developed methods to prepare porous carbons with tunable pore size distributions from inexpensive carbohydrate based precursors. The use of low-cost feedstocks and processing steps greatly lowers the production costs. During this project with the assistance of Maxwell Technologies, we found that an impurity was limiting the performance of our carbon and the major impurity found was sulfur. A new carbon with low sulfur content was made and found that the performance of the carbon was greatly improved. We also scaled-up the process to pre-production levels and we are currently able to produce 0.25 tons/year of activated carbon. We could easily double this amount by purchasing a second rotary kiln. More importantly, we are working with MeadWestvaco on a Joint Development Agreement to scale-up the process to produce hundreds of tons of high quality, inexpensive carbon per year based on our processes.

Dr. Steven D. Dietz

2007-01-10

135

Fabrication of activated carbon fibers/carbon aerogels composites by gelation and supercritical drying  

E-print Network

Fabrication of activated carbon fibers/carbon aerogels composites by gelation and supercritical August 2003) Activated carbon fiber/carbon aerogel (ACF/CA) composites were fabricated by gelling. The ACFs can reinforce the related carbon aerogels when they originally have low mass density and are weak

Liu, Jie

136

Modeling the selectivity of activated carbons for efficient separation of hydrogen and carbon dioxide  

E-print Network

the separation of hydrogen and carbon dioxide via adsorption in activated carbons. In the simulations, both hydrogen and carbon dioxide molecules are modeled as Lennard-Jones spheres, and the activated carbons essentially no preference over the two gases and the selectivity of carbon dioxide relative to hydrogen falls

Wu, Jianzhong

137

Activated carbon monoliths for methane storage  

NASA Astrophysics Data System (ADS)

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

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

2012-02-01

138

Cyclic process for producing methane from carbon monoxide with heat removal  

DOEpatents

Carbon monoxide-containing gas streams are converted to methane by a cyclic, essentially two-step process in which said carbon monoxide is disproportionated to form carbon dioxide and active surface carbon deposited on the surface of a catalyst, and said carbon is reacted with steam to form product methane and by-product carbon dioxide. The exothermic heat of reaction generated in each step is effectively removed during each complete cycle so as to avoid a build up of heat from cycle-to-cycle, with particularly advantageous techniques being employed for fixed bed, tubular and fluidized bed reactor operations.

Frost, Albert C. (Congers, NY); Yang, Chang-lee (Spring Valley, NY)

1982-01-01

139

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

140

Preparation of activated carbons with mesopores by use of organometallics  

SciTech Connect

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

Yamada, Yoshio; Yoshizawa, Noriko; Furuta, Takeshi [National Institute for Resources and Environment, Tsukuba, Ibaraki (Japan)] [and others

1996-12-31

141

Activated carbon produced from an Illinois Basin coal  

Microsoft Academic Search

Activated carbons were produced from an Illinois Basin bituminous coal (IBC-106) by a three-step process: oxidation of the coal in air at 150–250 °C for 2–40 hours, devolatilization of these oxidized coals in nitrogen at 500–730 °C for 1 hour and activation (gasification) of the chars in 45% steam, 4% oxygen in nitrogen at 730–880 °C for 3.5–96 hours. Products

Jian Sun; E. J. Hippo; H. Marsh; W. S. O'Brien; J. C. Crelling

1997-01-01

142

USING POWDERED ACTIVATED CARBON: A CRITICAL REVIEW  

EPA Science Inventory

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

143

MODELING MERCURY CONTROL WITH POWDERED ACTIVATED CARBON  

EPA Science Inventory

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

144

Granular Activated Carbon Filter-Adsorber Systems  

Microsoft Academic Search

The design, operation, and performance of granular activated carbon (GAC) filter-adsorbers were documented and potential problems were identified by means of a survey of operating plants and a review of the literature. It was found that GAC as a total or partial replacement for sand is as effective as conventional filtration media for removing turbidity, provided an appropriate medium size

Sandra L. Graese; Vernon L. Snoeyink; Ramon G. Lee

1987-01-01

145

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...

146

Inorganic Carbon Cycling and the Biogeochemical Processes in Hudson Bay  

NASA Astrophysics Data System (ADS)

Coastal seas, like Hudson Bay, are biogeochemically active areas with high primary productivity. High productivity can be expected to lead to fractionation of 13C/12C creating depletion of 12C isotope of Dissolved Inorganic Carbon (12CDIC) in the surface and enrichment of 12CDIC in deeper waters. The increase of anthropogenic CO2 concentration can have drastic impacts on the biogeochemical properties of the ocean. Since the Arctic and coastal seas are primarily sensitive to these changes, assessing the carbon cycle of this area is very important for future studies. We present the carbon cycle and related data from the Arctic Net 2010 Cruise. We investigate and assess the processes governing the carbon cycle over the entire water column of Hudson Bay. We find that the deep waters of Hudson Bay are Pacifically derived and do not interact with Atlantic waters beyond the mouth of the Bay. River input greatly affect the waters of Hudson Bay. Also, the longer residence time of the deep Hudson Bay waters allows the accumulation of products due to various biogeochemical and physical processes. These include respiration of organic matter, which causes greater DIC and lower del13C values at depth, and brine formation, which increases salinity, DIC and alkalinity. The eastern side of Hudson is observed to have greater DIC concentrations and is isotopically lighter in del13C than the western side.

Pengelly, Leah; Thomas, Helmuth; Burt, William; Papakyriakou, Tim; Miller, Lisa

2014-05-01

147

PRODUCTION OF ACTIVATED CARBON FROM BAMBOO USING CHEMICAL AND STEAM ACTIVATIONS  

Microsoft Academic Search

Bamboo is a natural resource in Malaysia as it takes only several months to grow and be ready for harvesting. Primary processing of bamboo for conversion into specified products generates a large amount of residues is generated. This residue could be effectively converted into value-added products such as activated carbon and charcoal. There are two phases in this progress activity

E. Puad Mahanim; J. Rafidah

148

Carbon Dioxide Sequestration Industrial-scale processes are available for separating carbon dioxide from the post-  

E-print Network

Carbon Dioxide Sequestration Industrial-scale processes are available for separating carbon dioxide dioxide separation and sequestration because the lower cost of carbon dioxide separation from for injection of carbon dioxide into oil or gas-bearing formations. An advantage of sequestration involving

149

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

SciTech Connect

A novel, three-step process for the production of high-quality activated carbons from macadamia nut shell and coconut shell charcoals is described. In this process the charcoal is (1) heated to a high temperature (carbonized), (2) oxidized in air following a stepwise heating program from low (ca. 450 K) to high (ca. 660 K) temperatures (oxygenated), and (3) heated again in an inert environment to a high temperature (activated). By use of this procedure, activated carbons with surface areas greater than 1,000 m{sub 2}/g are manufactured with an overall yield of 15% (based on the dry shell feed). Removal of carbon mass by the development of mesopores and macropores is largely responsible for increases in the surface area of the carbons above 600 m{sub 2}/g. Thus, the surface area per gram of activated carbon can be represented by an inverse function of the yield for burnoffs between 15 and 60%. These findings are supported by mass-transfer calculations and pore-size distribution measurements. A kinetic model for gasification of carbon by oxygen, which provides for an Eley-Rideal type reaction of a surface oxide with oxygen in air, fits the measured gasification rates reasonably well over the temperature range of 550--660 K.

Tam, M.S.; Antal, M.J. Jr.

1999-11-01

150

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

151

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

152

Pore structure of the activated coconut shell charcoal carbon  

NASA Astrophysics Data System (ADS)

The development of activated carbon from coconut shell charcoal has been investigated by using physical method to determine the influence of activation parameters in term of temperature, argon gas pressure and time period on the pore structure of the activated carbon. The coconut shell charcoal was produced by pyrolisis process at temperature of about 75 - 150 °C for 6 hours. The charcoal was activated at various temperature (532, 700 and 868 °C), argon gas pressure (6.59, 15 and 23.4 kgf/cm2) and time period of (10, 60 and 120 minutes). The results showed that the pores size were reduced and distributed uniformly as the activation parameters are increased.

Budi, E.; Nasbey, H.; Yuniarti, B. D. P.; Nurmayatri, Y.; Fahdiana, J.; Budi, A. S.

2014-09-01

153

Effect of microwave heating on the regeneration of modified activated carbons saturated with phenol  

NASA Astrophysics Data System (ADS)

The purpose of this work was to investigate the effect of microwave irradiation on the regeneration of modified activated carbons (GAC/MW, GAC/Ni, and GAC/Cu). The untreated activated carbon (GAC pure) was used for blank experiment. Microwave heating was used for preparation and regeneration of the modified activated carbons. The effect of loading Ni2+ and Cu2+ ions on the activated carbon adsorption capacity was investigated. The results showed that the activated carbon loaded with Ni2+ has no significant effect on phenol adsorption, while the adsorption capacity of activated carbon loaded with Cu2+ significantly decreased. Microwave irradiation showed a positive effect on activated carbon adsorption capacity. Under optimal conditions, the results showed that there was no effect when changing temperature and pH. The effect of ions Ni2+ and Cu2+ loaded into activated carbon were also investigated. During the regeneration process, the activated carbon loaded with Ni2+ showed a strong microwave energy adsorption than the activated carbon loaded with Cu2+. The effect increasing Ni2+ quantity decreases the activated carbon regeneration efficiency. During the regeneration of activated carbons, the highest temperature was observed in the cases of GAC/Ni. During regeneration, the temperature increases when the quantity Ni2+ loaded increases. The regeneration efficiency of activated carbons reaches 98 % even after 10 times of regeneration cycles. After several regenerations, MW/GAC and GAC/Ni regeneration efficiency was high, while regeneration efficiency of GAC/Cu decreased considerably. GAC regeneration efficiency also decreased several cycles. During regeneration process, phenol was simply desorbed from activated carbons under microwave irradiation.

Ondon, B. S.; Sun, B.; Yan, Z. Y.; Zhu, X. M.; liu, H.

2014-01-01

154

Selective activation of carbon-carbon bonds next to a carbonyl group  

NASA Astrophysics Data System (ADS)

ORGANOMETALLIC complexes are used to effect a wide range of catalytic transformations in organic synthesis, such as the activation of C-H bonds1,2. Carbon-carbon bonds, however, are generally unreactive towards transition metals under homogeneous conditions. C-C bond activation by a process of oxidative addition to soluble transition-metal complexes has been limited mostly to stoichiometric (not catalytic) reactions1,3-7,18, to highly strained substrates such as cyclopropane and cubane1,8-11 or to chelating ketones19. Here we present a synthetically useful process of selective C-C bond activation in which the C-C bond adjacent to a carbonyl group is opened by insertion of a soluble rhodium(I) complex. The resulting organometallic intermediate can be transformed to a variety of products in a way that regenerates the rhodium complex. We anticipate that this catalytic scheme will have considerable utility in organic synthesis.

Murakami, Masahiro; Amii, Hideki; Ito, Yoshihiko

1994-08-01

155

Influence of process water quality on hydrothermal carbonization of cellulose.  

PubMed

Hydrothermal carbonization (HTC) is a thermal conversion process that has been shown to be environmentally and energetically advantageous for the conversion of wet feedstocks. Supplemental moisture, usually in the form of pure water, is added during carbonization to achieve feedstock submersion. To improve process sustainability, it is important to consider alternative supplemental moisture sources. Liquid waste streams may be ideal alternative liquid source candidates. Experiments were conducted to systematically evaluate how changes in pH, ionic strength, and organic carbon content of the initial process water influences cellulose carbonization. Results from the experiments conducted evaluating the influence of process water quality on carbonization indicate that changes in initial water quality do influence time-dependent carbonization product composition and yields. These results also suggest that using municipal and industrial wastewaters, with the exception of streams with high CaCl2 concentrations, may impart little influence on final carbonization products/yields. PMID:24398151

Lu, Xiaowei; Flora, Joseph R V; Berge, Nicole D

2014-02-01

156

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

157

Characteristic and mercury adsorption of activated carbon produced by CO 2 of chicken waste  

Microsoft Academic Search

Preparation of activated carbon from chicken waste is a promising way to produce a useful adsorbent for Hg removal. A three-stage activation process (drying at 200°C, pyrolysis in N2 atmosphere, followed by CO2 activation) was used for the production of activated samples. The effects of carbonization temperature (400–600°C), activation temperature (700–900°C), and activation time (1–2.5 h) on the physicochemical properties

Yaji HUANG; Baosheng JIN; Zhaoping ZHONG; Wenqi ZHONG; Rui XIAO

2008-01-01

158

Mesophase Behavior Fundamental to the Processing of Carbon-Carbon Composites.  

National Technical Information Service (NTIS)

Investigated are the behaviors of the carbonaceous mesophase that significantly influence the processing of carbon-carbon composites. An understanding of those behaviors will provide insights for more effective and economical fabrication of such composite...

J. L. White

1982-01-01

159

Nano Structured Activated Carbon for Hydrogen Storge  

SciTech Connect

Development of a nanostructured synthetic carbons materials that have been synthesized by thermal-decomposition of aromatic rich polyether such as poly(ether ether ketone) (PEEK) is reported. These polymers based nanostructured carbons efficacious for gas adsorption and storage and have Brunauer-Emmett-Teller (BET) surface area of more than 3000 m2/g, and with average pore diameter of < 2nm. Surface-area, pore characteristics, and other critical variables for selecting porous materials of high gas adsorption capacities are presented. Analysis of the fragments evolved under various carbonization temperatures, and the correlation between the activation and carbonization temperatures provides a mechanistic perspective of the pore evolution during activation. Correlations between gas (N2 and H2) adsorption capacity and porous texture of the materials have been established. The materials possess excellent hydrogen storage properties, with hydrogen storage capacity up to 7.4 wt% (gravimetric) and ~ 45 g H2 L-1 (volumetric) at -196oC and 6.0 MPa.

Israel Cabasso; Youxin Yuan

2013-02-27

160

Processing methods, characteristics and adsorption behavior of tire derived carbons: a review.  

PubMed

The remarkable increase in the number of vehicles worldwide; and the lack of both technical and economical mechanisms of disposal make waste tires to be a serious source of pollution. One potential recycling process is pyrolysis followed by chemical activation process to produce porous activated carbons. Many researchers have recently proved the capability of such carbons as adsorbents to remove various types of pollutants including organic and inorganic species. This review attempts to compile relevant knowledge about the production methods of carbon from waste rubber tires. The effects of various process parameters including temperature and heating rate, on the pyrolysis stage; activation temperature and time, activation agent and activating gas are reviewed. This review highlights the use of waste-tires derived carbon to remove various types of pollutants like heavy metals, dye, pesticides and others from aqueous media. PMID:25001042

Saleh, Tawfik A; Gupta, Vinod Kumar

2014-09-01

161

Fabrication of novel micro-nano carbonous composites based on self-made hollow activated carbon fibers  

NASA Astrophysics Data System (ADS)

The hollow activated carbon fibers (HACF) were prepared by using commercial polypropylene hollow fiber (PPHF) as the template, and phenol-formaldehyde resin (PF) as carbon precursors. Final HACF was formed through the thermal decomposition and carbonization of PF at 700 °C under the nitrogen atmosphere, and activation at 800 °C with carbon dioxide as the activating agent, consecutively. Then, carbon nanotubes (CNTs) were grown by chemical vapor deposition (CVD) techniques using the as-grown porous HACF as substrate. The growth process was achieved by pyrolyzing ethanol steam at 700 °C using nickel as catalyst. Finally, CNTs was grown successfully on the substrate, and a novel tree-like micro-nano carbonous structure CNTs/HACF was fabricated. The as-grown HACF and micro-nano CNTs/HACF were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), and thermogravimetric analysis (TG), respectively. Moreover, the formation mechanisms were also discussed.

Kong, Yuxia; Qiu, Tingting; Qiu, Jun

2013-01-01

162

Comparison on pore development of activated carbon produced from palm shell and coconut shell  

Microsoft Academic Search

A series of experiments were conducted to compare the pore development in palm-shell and coconut-shell-based activated carbons produced under identical experimental conditions. Carbonization and activation processes were carried out at 850 °C using a fluidized bed reactor. Within the range of burn-off studied, at any burn-off, the micropore and mesopore volumes created in palm-shell-based activated carbon were always higher than

Wan Mohd Ashri Wan Daud; Wan Shabuddin Wan Ali

2004-01-01

163

Carbon Strategy for the Food Industry FAPC Food Process Engineer  

E-print Network

issues for food processors: · Green house gas (GHG) · Carbon footprint · Life cycle assessment (LCA application of water (sprinklers). The carbon footprint of a food manufacturing facility is a measure of the equivalent carbon dioxide emissions associated with ongoing activities. Calculation of the footprint can

Balasundaram, Balabhaskar "Baski"

164

The role of carbonate as a catalyst of Fenton-like reactions in AOP processes: CO3?(-) as the active intermediate.  

PubMed

Kinetic and DFT results for the carbonate catalysed Co(H2O)6(2+) + H2O2 Fenton-like reaction suggest a mechanism involving the formation of a cyclic transient, cyclic-(CO4)Co(II)(OOH)(H2O)2(-) that decomposes into Co(II)(H2O)(OOH)(OH)2 + CO3?(-), i.e. no OH? radicals are involved. Plausible biological implications are pointed out. PMID:25223650

Burg, Ariela; Shamir, Dror; Shusterman, Inna; Kornweitz, Haya; Meyerstein, Dan

2014-11-01

165

Mechanism of action of electrochemically active carbons on the processes that take place at the negative plates of lead-acid batteries  

Microsoft Academic Search

It is known that negative plates of lead-acid batteries have low charge acceptance when cycled at high rates and progressively accumulate lead sulphate on high-rate partial-state-of-charge (HRPSoC) operation in hybrid-electric vehicle (HEV) applications. Addition of some carbon or graphite forms to the negative paste mix improves the charge efficiency and slows down sulfation of the negative plates. The present investigation

D. Pavlov; T. Rogachev; P. Nikolov; G. Petkova

2009-01-01

166

Adsorption of Nonylphenol onto Granular Activated Carbon  

Microsoft Academic Search

The applicability of granular activated carbon (GAC)filtration for the removal of the xeno-estrogenicmicropollutant nonylphenol (NP) is evaluated using batchadsorption data. From the obtained adsorption data, it wasapparent that with contact times of 4 d and 24 hr and GACdosages of 1 and 0.1 g L-1 no saturationof the GAC could be obtained with NP total contaminantloadings up to 10 000

Tom Tanghe; Willy Verstraete

2001-01-01

167

Phenol degradation by microorganisms adsorbed on activated carbon  

Microsoft Academic Search

The phenol degradation by Candida sp. and Pseudomonas sp. immobilized on activated carbon was investigated. Thanks to its great adsorptive surface, activated carbon is suited as supporting material for microorganisms and also provides a high adsorption capacity for phenol.

H. M. Ehrhardt; H. J. Rehm

1985-01-01

168

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

SciTech Connect

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

Sai, P.M.S.; Ahmed, J. [Bhabha Atomic Research Centre, Kalpakkam (India). Centralised Waste Management Facility; Krishnaiah, K. [Indian Inst. of Tech., Madras (India). Dept. of Chemical Engineering

1997-09-01

169

Elastic Pore Structure in Activated Carbon  

NASA Astrophysics Data System (ADS)

Adsorbent materials such as activated carbon and Metal-Organic Frameworks (MOFs) have received significant attention as a potential storage material for hydrogen and natural gas. Typically the adsorbent material is assumed to consist of rigid slit- or cylindrical-shaped pores. Recent work, for MOFs in particular, revealed the importance of the mechanical response of the adsorbent in the presence of an adsorbate. In the absence of an adsorbate the pore structure is defined by the size, shape and inter-molecular interactions of the constituent parts of the solid. Here, we demonstrate the flexibility of pore walls in activated carbon and the effect this has on the pore structure of the bulk samples. The interaction is modeled as a competition between Van der Waals interactions between neighboring walls and a resistance to bending due to the rigidity of graphene. Minimal energy configurations were calculated analytically for a simplified potential and numerically for a more realistic potential. The pore structures are discussed in the context of pore measurements on activated carbon samples.

Connolly, M. J.; Wexler, Carlos

2011-11-01

170

Preparation and characterization of activated carbon from demineralized tyre char  

NASA Astrophysics Data System (ADS)

Activated carbon is the most adsorbing material for industrial waste water treatment. For wider applications, the main consideration is to manufacture activated carbon from low cost precursors, which are easily available and cost effective. One such source is scrap tyres. Recently much effort has been devoted to the thermal degradation of tyres into gaseous and liquid hydrocarbons and solid char residue, all of which have the potential to be processed into valuable products. As for solid residue, char can be used either as low-grade reinforcing filler or as activated carbon. The product recovered by a typical pyrolysis of tyres are usually, 33-38 wt% pyrolytic char, 38-55 wt% oil and 10-30 wt% solid fractions. In the present work activated carbon was prepared from pyrolyzed tyre char (PC). Demineralization involves the dissolution of metal into acids i.e. HCl, HNO3 and H2SO4 and in base i.e. NaOH. Different concentration of acid and base were used. Sodium hydroxide showed maximum amount of metal oxide removal. Further the concentration of sodium hydroxide was varied from 1N to 6N. As the concentration of acid are increased demineralization increases. 6N Sodium hydroxide is found to be more effective demineralising agent of tyre char.

Manocha, S.; Prasad, Guddu R.; Joshi, Parth.; Zala, Ranjitsingh S.; Gokhale, Siddharth S.; Manocha, L. M.

2013-06-01

171

Production of activated carbon from acorns and olive seeds  

Microsoft Academic Search

This study has been designed to produce activated carbon from acorns and olive seeds. The starting materials are low in cost and they are the cause of solid waste pollution problems in Jordan. A chemical procedure is used to produce the required activated carbon. The results indicate that activated carbon produced from acorns compares favorably with that from olive seeds

Walid K Lafi

2001-01-01

172

Studies of activated carbons used in double-layer capacitors  

Microsoft Academic Search

Various kinds of activated carbon materials were investigated by means of nitrogen gas adsorption, AC impedance and constant current discharge techniques. The relation between the intrinsic pore size distribution of activated carbon materials and their electrochemical performance as electrodes of supercapacitor were discussed in detail. Activated carbons with larger pores are found to be more suitable for high power applications.

Deyang Qu; Hang Shi

1998-01-01

173

Static Sorption of Phenol and 4-Nitrophenol onto Composite Geomaterials based on Montmorillonite, Activated Carbon and  

E-print Network

and 4-nitrophenol (4NP) onto solid sorbents derived from mixtures of montmorillonite, activated carbon by batch testing on geomaterials with various X1 values at 20 �C and at different pH values (from 3 to 8 degradation processes, chemical oxidation and biological digestion, in which sorption onto activated carbon

Paris-Sud XI, Université de

174

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

175

Factors Influencing The Adsorption Of Gold-Iodide Onto Activated Carbon  

Microsoft Academic Search

Activated carbon has found increasing application during the past decade as an adsorbent for gold from cyanide leached pulps. As result of practical and theoretical advancements in recent years, the carbon-in-pulp (CIP) process has become the preferred method for gold extraction from cyanided slurries. Lately, environmental considerations have led to the investigation of alternative leaching processes. One group of lixiviants

P. A. M. Teirlinck; F. W. Petersen

1995-01-01

176

Ultrasound-assisted synthesis and processing of carbon materials  

NASA Astrophysics Data System (ADS)

Part I: Porous carbons are of interest in many applications because of their high surface areas and other physicochemical properties, and much effort has been directed towards developing new methods for controlling the porosity of carbons. Ultrasonic spray pyrolysis (USP) is an aerosol method suitable for large-scale, continuous synthesis of materials. Ultrasound is used to create aerosol droplets of a precursor solution which serve as micron-sized spherical reactors for materials synthesis. This work presents a precursor system for the template-free USP synthesis of porous carbons using low-cost precursors that do not evolve or require hazardous chemicals: sucrose was used as the carbon source, and sodium carbonate, sodium bicarbonate, or sodium nitrate was added as a decomposition catalyst and porogen. The USP carbons had macroporous interiors and microporous shells with surface areas as high as 800 m2/g and a narrow pore size distribution. It was determined that the interior porosity was a result of the gas evolution from salt decomposition and not from the presence of a salt template. Porous carbon is frequently used as a catalyst support because it provides high surface area and it is chemically and physically stable under many anoxic reaction conditions. Typically, the preparation of supported catalysts requires multiple steps for carbonization and metal impregnation. In this work, iron-impregnated porous carbon microspheres (Fe-C) were prepared by a one-step USP process by incorporating both the carbon and metal sources into the precursor solution. Carbonization, pore formation, metal impregnation, and metal activation occurred simultaneously to produce Fe-C materials with surface areas as high as 800 m2/g and up to 10 wt% Fe incorporated as nanoparticles < 20 nm in diameter. Fe-C was used as a catalyst to reduce aqueous hexavalent chromium, which demonstrated the accessibility of the iron nanoparticles despite the fact that they are likely encapsulated in the porous carbon support. Part II: The effects of high intensity ultrasound arise from acoustic cavitation: the formation, growth, and collapse of bubbles in a liquid. Bubble collapse produces intense localized heating (˜5000 K), high pressures (˜300 atm), and enormous heating and cooling rates (>109 K/sec). In solid-liquid slurries, surface erosion and particle fracture occur due to the shockwaves and microjets formed from asymmetric bubble collapse at extended surfaces. The chemical and physical effects of ultrasound have been studied as an adjunct to the traditional chemical pretreatment of lignocellulosic biomass for ethanol production. Lignocellulosic biomass consists of cellulose, hemicellulose, and lignin. The surface effects of ultrasound were used in this work to increase the accessibility of the cellulose, which can be converted to glucose and then fermented into ethanol. The lignocellulosic biomass used in this work was Miscanthus x giganteus (Mxg) which was grown at the University of Illinois at Urbana-Champaign. The chemical effects of NaOH pretreatment on Mxg were enhanced by ultrasound: greater delignification and a significant increase in the amount of pores >5 nm were observed. ˜ 70% of the theoretical glucose yield was obtained by enzymatic saccharification of the ultrasound-assisted NaOH-pretreated Mxg; this is comparable to the yields that can be obtained by traditional alkaline pretreatments, but it was achieved in a shorter time and at a lower temperature. Because the apparatus used for laboratory studies is not a likely device for scale-up, the economics of ultrasound with regards to energy balance are not yet resolved.

Fortunato, Maria E.

177

Carbon Cycle in the Lab: Carbon Products and the Processes That Link Them  

NSDL National Science Digital Library

This lab teaches students about the nature of carbon, the different types of compounds it exists in (e.g. charcoal, glucose, carbon dioxide), the biochemical reactions it takes part in (photosynthesis and respiration), the range of processes that carbon and carbon compounds are involved in on Earth, and how these link together form the carbon cycle. They will get a feel for how the whole carbon cycle works by turning the laboratory into a model of the carbon cycle and seeing how the different things that are produced in the cycle (the products) fit together with the way those products are made (the processes). The site contains teacher notes, a list of required materials, student instructions and questions, and a diagram of the carbon cycle.

178

Novel thermal gradient chemical vapor infiltration process for carbon-carbon composites  

Microsoft Academic Search

Solid cylindrical carbon-carbon composites were processed using conventional thermal gradient chemical vapor infiltration. High thermal conductivity (55 W\\/m·°C) carbon fibers (48 k) were inserted in the center of a cylindrical low thermal conductivity (0.15 W\\/m·°C) needle punched carbon felt preform, to create a thermal gradient because of the difference in thermal conductivities. The hottest portion (900–1200 °C) was along the

Shameel Farhan; Ke-zhi LI; Ling-jun GUO

2007-01-01

179

Facilitation of high-rate NADH electrocatalysis using electrochemically activated carbon materials.  

PubMed

Electrochemical activation of glassy carbon, carbon paper and functionalized carbon nanotubes via high-applied-potential cyclic voltammetry leads to the formation of adsorbed, redox active functional groups and increased active surface area. Electrochemically activated carbon electrodes display enhanced activity toward nicotinamide adenine dinucleotide (NADH) oxidation, and more importantly, dramatically improved adsorption of bioelectrochemically active azine dyes. Adsorption of methylene green on an electroactivated carbon electrode yields a catalyst layer that is 1.8-fold more active toward NADH oxidation than an electrode prepared using electropolymerized methylene green. Stability studies using cyclic voltammetry indicate 70% activity retention after 4000 cycles. This work further facilitates the electrocatalysis of NADH oxidation for bioconversion, biosensor and bioenergy processes. PMID:24780505

Li, Hanzi; Li, Rui; Worden, Robert M; Barton, Scott Calabrese

2014-05-14

180

Study of activated carbon modified with sodium carbonate as a possible antacid drug  

Microsoft Academic Search

Activated carbon was modified with different sodium carbonate solutions (0.5 to 3.0 M) to produce a series of possible antacids. The modified carbon was characterized by means of XRD and BET surface area measurements. XRD confirmed the presence of bicarbonate species on the surface of the modified carbons, while the surface areas indicated that microporous of the solids were partially

Carlos F. Linares; Alexia Palencia; Mireya R. Goldwasser; Karina Rodríguez

2006-01-01

181

Adsorbed natural gas storage with activated carbon  

SciTech Connect

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

Sun, Jian; Brady, T.A.; Rood, M.J. [Univ. of Illinois, Urbana, IL (United States)] [and others

1996-12-31

182

CHROMIUM REMOVAL BY ACTIVATED CARBON PREPARED FROM COCONUT SHELL  

Microsoft Academic Search

One of the main fields of activated carbons employment is pollution control. The features ofactivated carbons features such as high adsorption capacity and low cost justify their use in the removal of different pollutant agents such as heavy metals. Chromium is one of the main pollutants and the comprehension of its uptake mechanism in the activated carbon is an important

R. M. Schneider

183

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...

184

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, Wu; Borong, Bao; Ruimin, Zhou; Jinliang, Zhu; Longxin, Hu

1998-10-01

185

REPEATED REDUCTIVE AND OXIDATIVE TREATMENTS ON GRANULAR ACTIVATED CARBON  

EPA Science Inventory

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

186

Activated carbons from steam exploded wood  

SciTech Connect

In a continuing experimental program, we are investigating the conversion of hardwoods, such as white oak (Quercus alba) to activated carbons by chemical activation with phosphoric acid. The aims of the research are to establish the relationships between chemical and morphological change and porosity development, with the long term goal of developing new adsorbents with controlled porosity and surface chemistry, through the selection of the precursor, reagent, and reaction parameters. The research is further directed to enhancing the use of wood materials, some of which are not appropriate feedstocks for conventional industrial applications, and to providing potential solutions to the problem of the economic utilization of wood wastes from primary and secondary wood industries.

Jagtoyen, M.; Derbyshire, F. [Univ. of Kentucky, Lexington, KY (United States); Wright, R.S.; Glasser, W. [Virginia Polytechnical Institute, Blacksburg, VA (United States)

1995-12-31

187

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)] [Degussa AG, Hanau (Germany)

1994-12-01

188

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...

189

Acid sorption regeneration process using carbon dioxide  

DOEpatents

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.

King, C. Judson (Kensington, CA); Husson, Scott M. (Anderson, SC)

2001-01-01

190

Catalytic Effect of Activated Carbon and Activated Carbon Fiber in Non-Equilibrium Plasma-Based Water Treatment  

NASA Astrophysics Data System (ADS)

Catalysis and regeneration efficiency of granular activated carbon (GAC) and activated carbon fiber (ACF) were investigated in a non-equilibrium plasma water treatment reactor with a combination of pulsed streamer discharge and GAC or ACF. The experimental results show that the degradation efficiency of methyl orange (MO) by the combined treatment can increase 22% (for GAC) and 24% (for ACF) respectively compared to pulsed discharge treatment alone, indicating that the combined treatment has a synergetic effect. The MO degradation efficiency by the combined treatment with pulsed discharge and saturated GAC or ACF can increase 12% and 17% respectively compared to pulsed discharge treatment alone. Both GAC and ACF show catalysis and the catalysis of ACF is prominent. Meanwhile, the regeneration of GAC and ACF are realized in this process. When H2O2 is introduced into the system, the utilization efficiency of ozone and ultraviolet light is improved and the regeneration efficiency of GAC and ACF is also increased.

Zhang, Yanzong; Zheng, Jingtang; Qu, Xianfeng; Yu, Weizhao; Chen, Honggang

2008-06-01

191

Adsorption of Carbon Dioxide onto Activated Carbon and Nitrogen-Enriched Activated Carbon: Surface Changes, Equilibrium, and Modeling of Fixed-Bed Adsorption  

Microsoft Academic Search

It has been reported that the CO2 adsorption capacity of the N-enriched activated carbon can increase or decrease. In this study a commercial activated carbon was functionalized with 3-chloropropylamine hydrochloride and its adsorption characteristics in a fixed-bed column were investigated. The N-enriched activated carbon presented lower BET surface area than the original activated carbon suggesting that the nitrogen incorporation partially

Tirzhá L. P. Dantas; Suélen M. Amorim; Francisco Murilo T. Luna; Ivanildo J. Silva Jr; Diana C. S. de Azevedo; Alírio E. Rodrigues; Regina F. P. M. Moreira

2009-01-01

192

Process Based Belowground Carbon Dioxide Modeling in a Desert Ecosystem  

Microsoft Academic Search

We describe a study to integrate and assess biological and physical processes that govern belowground carbon dioxide levels at a semi-arid grassland near Canyonlands National Park. Carbon dioxide concentrations were measured every 30 minutes at 5 and 15 cm depth within the rooting zones of the two dominant grass species, Stipa hymenoides and Hilaria jamesii, as well as the interspace

J. M. Zobitz; D. R. Bowling

2003-01-01

193

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

2013-06-01

194

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

195

Surface modification, characterization and adsorptive properties of a coconut activated carbon  

NASA Astrophysics Data System (ADS)

A coconut activated carbon was modified using chemical methods. Different concentration of nitric acid oxidation of the conventional sample produced samples with weakly acidic functional groups. The oxidized samples were characterized by scanning electron micrograph, nitrogen absorption-desorption, Fourier transform infra red spectroscopy, Bothem method, pH titration, adsorption capacity of sodium and formaldehyde, and the adsorption mechanism of activated carbons was investigated. The results showed that BET surface area and pore volume of activated carbons were decreased after oxidization process, while acidic functional groups were increased. The surface morphology of oxidized carbons looked clean and eroded which was caused by oxidization of nitric acid. The oxidized carbons showed high adsorption capacity of sodium and formaldehyde, and chemical properties of activated carbon played an important role in adsorption of metal ions and organic pollutants.

Lu, Xincheng; Jiang, Jianchun; Sun, Kang; Xie, Xinping; Hu, Yiming

2012-08-01

196

The Carbon Cycle and its Role in Climate Change: Activity 1  

NSDL National Science Digital Library

In this activity (on page 1), learners role play as atoms to explore how atoms can be rearranged to make different materials. Learners group together and link arms or hold hands to form chemical bonds and act out the processes of photosynthesis and respiration. Use this activity to introduce the carbon cycle and follow this activity with two associated activities from the same resource.

Management, Us B.; Agency, Us E.; Service, Us F.; Service, Us F.; Administration, National A.; Administration, National A.

2009-01-01

197

CYANIDE REMOVAL FROM REFINERY WASTEWATER USING POWDERED ACTIVATED CARBON  

EPA Science Inventory

The objective of this project was to evaluate the removal of low level cyanide in petroleum refinery wastewater by the addition of powdered activated carbon and cupric chloride to an activated sludge unit. The activated carbon and cupric chloride act as a catalyst in the oxidatio...

198

Colonization of Biological Activated Carbon in Drinking Water Purification  

Microsoft Academic Search

The colonization of columnar activated carbon was developed. Some analysis of several physical–chemical, biochemical and microbiological methods (indicators) used to characterize the BAC biofilm's composition and activity was provided. The filtration column filled with columnar activated carbon was operated incessantly for 72 days in the condition of natural colonization in a dynamic flow and poor nutritional status. The mature biofilm

He Wang; Zhonglin Chen; Jimin Shen; Feifei Xiang; Yu Liu; Xu Zhai; Yue Liu

2010-01-01

199

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

200

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

201

Enhanced Cellular Activation with Single Walled Carbon Nanotube Bundles  

E-print Network

Enhanced Cellular Activation with Single Walled Carbon Nanotube Bundles Presenting Antibody Stimuli the body using single walled carbon nanotube (SWNT) bundles presenting antibody stimuli. Owing to the large of lymphocytes, useful for basic science applications and clinical immunotherapy. Single walled carbon nanotubes

Fahmy, Tarek

202

Activated carbon–carbon nanotube composite porous film for supercapacitor applications  

Microsoft Academic Search

Activated carbon\\/carbon nanotube composite electrodes have been assembled and tested in organic electrolyte (NEt4BF4 1.5M in acetonitrile). The performances of such cells have been compared with pure activated carbon-based electrodes. CNTs content of 15wt.% seems to be a good compromise between power and energy, with a cell series resistance of 0.6?cm2 and an active material capacitance as high as 88Fg?1.

Pierre-Louis Taberna; Geoffroy Chevallier; Patrice Simon; Dominique Plée; Thierry Aubert

2006-01-01

203

Parallel Activation in Bilingual Phonological Processing  

ERIC Educational Resources Information Center

In bilingual language processing, the parallel activation hypothesis suggests that bilinguals activate their two languages simultaneously during language processing. Support for the parallel activation mainly comes from studies of lexical (word-form) processing, with relatively less attention to phonological (sound) processing. According to…

Lee, Su-Yeon

2011-01-01

204

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

205

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

206

Processing and Characterization of Carbon Nanotube Composites  

NASA Technical Reports Server (NTRS)

Recent advances in the synthesis of large-scale quantities of carbon nanotubes (CNT) have provided the opportunity to study the mechanical properties of polymer matrix composites using these novel materials as reinforcement. Nanocomp Technologies, Inc. currently supplies large sheets with dimensions up to 122 cm x 244 cm containing both single-wall and few-wall CNTs. The tubes are approximately 1 mm in length with diameters ranging from 8 to 12 nm. In the present study being conducted at NASA Langley Research Center (LaRC), single and multiple layers of CNT sheets were infused or coated with various polymer solutions that included commercial toughened-epoxies and bismaleimides, as well as a LaRC developed polyimide. The resulting CNT composites were tested in tension using a modified version of ASTM D882-12 to determine their strength and modulus values. The effects of solvent treatment and mechanical elongation/alignment of the CNT sheets on the tensile performance of the composite were determined. Thin composites (around 50 wt% CNT) fabricated from acetone condensed and elongated CNT sheets with either a BMI or polyimide resin solution exhibited specific tensile moduli approaching that of toughened epoxy/ IM7 carbon fiber unidirectional composites.

Can, Roberto J.; Grimsley, Brian W.; Czabaj, Michael W.; Siochi, Emilie J.; Hull, Brandon

2014-01-01

207

Preparation and Characterization of Activated Carbon from Gelam Wood Bark (Melaleuca cajuputi)  

Microsoft Academic Search

In this study, Gelam wood bark (Melaleuca cajuputi) was used as precursor to prepare the activated carbon. The preparation process consisted of ZnCl2 impregnation followed by carbonization in nitrogen at 500 o C for 3 hours and carbon dioxide for 1 hour. The optimum surface area was obtained at 25 % of ZnCl2, which is 1213 and 1443 m 2

Abdul Halim Abdullah; Anuar Kassim; Zulkarnain Zainal; Mohd Zobir Hussien; Dzulkefly Kuang; Faujan Ahmad; Ong Sim Wooi

208

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

209

Novel electro-fenton approach for regeneration of activated carbon.  

PubMed

An electro-Fenton-based method was used to promote the regeneration of granular activated carbon (GAC) previously adsorbed with toluene. Electrochemical regeneration experiments were carried out using a standard laboratory electrochemical cell with carbon paste electrodes and a batch electrochemical reactor. For each system, a comparison was made using FeSO4 as a precursor salt in solution (homogeneous system) and an Fe-loaded ion-exchange resin (Purolite C-100, heterogeneous system), both in combination with electrogenerated H2O2 at the GAC cathode. In the two cases, high regeneration efficiencies were obtained in the presence of iron using appropriate conditions of applied potential and adsorption-polarization time. Consecutive loading and regeneration cycles of GAC were performed in the reactor without great loss of the adsorption properties, only reducing the regeneration efficiency by 1% per cycle during 10 cycles of treatment. Considering that, in the proposed resin-containing process, the use of Fe salts is avoided and that GAC cathodic polarization results in efficient cleaning and regeneration of the adsorbent material, this novel electro-Fenton approach could constitute an excellent alternative for regenerating activated carbon when compared to conventional methods. PMID:23782426

Bañuelos, Jennifer A; Rodríguez, Francisco J; Manríquez Rocha, Juan; Bustos, Erika; Rodríguez, Adrián; Cruz, Julio C; Arriaga, L G; Godínez, Luis A

2013-07-16

210

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

2013-07-01

211

Pyrolysis of scrap tires and conversion of chars to activated carbon  

SciTech Connect

The primary objective of this work was to demonstrate the conversion of scrap tires to activated carbon. The authors have been successful in this endeavor, producing carbons with surface areas greater than 500 m[sup 2]/g and significant micropore volumes. Tire shreddings were pyrolyzed in batch reactors, and the pyrolysis chars activated by reaction with superheated steam. Solid products of pyrolysis and activation were studied with nitrogen adsorption techniques. They find that the porosity development during steam activation of tire pyrolysis char is similar to that reported for various other chars. A maximum in micropore volume is observed as a function of conversion, but the total surface area increases monotonically with conversion. They suggest that the activation process consists of micropore formation, followed by pore enlargement. The process conditions used in this study are a good starting point from which to optimize a process to convert tires to activated carbon.

Merchant, A.A.; Petrich, M.A. (Northwestern Univ., Evanston, IL (United States). Dept. of Chemical Engineering)

1993-08-01

212

Active carbon filter health condition detection with piezoelectric wafer active sensors  

Microsoft Academic Search

The impregnated active carbon used in air purification systems degrades over time due to exposure to contamination and mechanical effects (packing, settling, flow channeling, etc.). A novel approach is proposed to detect contamination in active carbon filters by combining the electromechanical impedance spectroscopy (EMIS) and electrochemical impedance spectroscopy (ECIS). ECIS is currently being used to evaluate active carbon filtration material;

Jingjing Bao; Victor Giurgiutiu; Glenn O. Rubel; Gregory W. Peterson; Thomas M. Ball

2011-01-01

213

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

214

Solution Processed Carbon Nanotube \\/PMMA Nano Composite Infrared Photodetectors  

Microsoft Academic Search

Solution processable nanostructured materials are of great interest for electronic and optical devices because of their enhance functionality, easy processibility, flexibility, and low cost of fabrication. We tested multi walled carbon nanotube networks dispersed in poly (methyl methacrylate) (PMMA) matrix for use as the infrared (IR) photodetectors at room temperature in ambient condition. Our study reveals both negative and positive

Yi Liu; Liwei Liu; Paul Stokes; Qun Huo; Saiful I. Khondaker

2008-01-01

215

Preparation of carbon blacks by liquid phase plasma (LPP) process.  

PubMed

In this study, carbon black nanoparticles were synthesized by Liquid Phase Plasma (LPP) technique; plasma generated in the organic solvent of benzene at 4.9 kV with the pulse frequency of 15 kHz and width of 5 micros transformed the carbon atoms in the solvent into carbon blacks by oxidation and reduction reactions. Graphite phase was found to be introduced into the carbon blacks without any additional processes due to the characteristics of LPP process, resulting in a higher G/D ratio of 0.92, compared to 0.83 of commercial Ketjen carbon blacks. For the performance improvement, heat treatment was employed and its parameters such as temperature and duration time were optimized in relation to the crystallinity and specific surface area of the carbon blacks. Carbon blacks heat treated at 450 degrees C in the air for 20 min were measured to have the discharge capacity of 1750 mAh/g and irreversible charging and discharging capacity ratio of 52.6%. PMID:24245259

Yun, Kang-Seop; Kim, Bo-Ra; Kang, Woo-Seung; Jung, Sang-Chul; Myung, Seung-Taek; Kim, Sun-Jae

2013-11-01

216

Supporting Information Unexpected Role of Activated Carbon in Promoting  

E-print Network

-min/L and then air-dried; and (iii) PSC particles were baked at. Activated Carbons, Modifications and Characterization. The suite of activated carbon particles and fibers used in this study included: (i) synthetic Ambersorb 572 particles from Rohm and Haas (Philadelphia, PA

Huang, Ching-Hua

217

Bioindication Potential of Carbonic Anhydrase Activity in Anemones  

E-print Network

Bioindication Potential of Carbonic Anhydrase Activity in Anemones and Corals AUBREY L. GILBERT levels of carbonic anhydrase (CA) were assessed in anemones Condylactis gigantea and Stichodactyla he has been done on CA activity in anemones and corals, two potential candidates for coral reef

Bermingham, Eldredge

218

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

219

Thin film micro carbon dioxide sensor using MEMS process  

Microsoft Academic Search

Pt\\/Na+ ion conductive ceramic thin film\\/Pt\\/carbonate (Na2CO3:BaCO3=1:1.7mol) system CO2 micro gas sensor was fabricated and the sensing properties were investigated. The Na+ ion conductive thin film was prepared by RF magnetron sputtering method. The thin film micro carbon dioxide sensor was prepared by using silicon process combined with MEMS technology.A NASICON thin film (2000–2500Å) as main layer of the device

Yeung-Il Bang; Kap-Duk Song; Byung-Su Joo; Jeung-Soo Huh; Soon-Don Choi; Duk-Dong Lee

2004-01-01

220

Process for derivatizing carbon nanotubes with diazonium species  

NASA Technical Reports Server (NTRS)

The invention incorporates new processes for the chemical modification of carbon nanotubes. Such processes involve the derivatization of multi- and single-wall carbon nanotubes, including small diameter (ca. 0.7 nm) single-wall carbon nanotubes, with diazonium species. The method allows the chemical attachment of a variety of organic compounds to the side and ends of carbon nanotubes. These chemically modified nanotubes have applications in polymer composite materials, molecular electronic applications and sensor devices. The methods of derivatization include electrochemical induced reactions thermally induced reactions (via in-situ generation of diazonium compounds or pre-formed diazonium compounds), and photochemically induced reactions. The derivatization causes significant changes in the spectroscopic properties of the nanotubes. The estimated degree of functionality is ca. 1 out of every 20 to 30 carbons in a nanotube bearing a functionality moiety. Such electrochemical reduction processes can be adapted to apply site-selective chemical functionalization of nanotubes. Moreover, when modified with suitable chemical groups, the derivatized nanotubes are chemically compatible with a polymer matrix, allowing transfer of the properties of the nanotubes (such as, mechanical strength or electrical conductivity) to the properties of the composite material as a whole. Furthermore, when modified with suitable chemical groups, the groups can be polymerized to form a polymer that includes carbon nanotubes ##STR00001##.

Tour, James M. (Inventor); Bahr, Jeffrey L. (Inventor); Yang, Jiping (Inventor)

2007-01-01

221

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

222

Basic dye adsorption on activated carbon  

Microsoft Academic Search

The adsorption of Victoria Blue dye (Basic Blue 26) on carbon has been investigated. Equilibrium data have been found to obey the Langmuir isotherm. The effects of contact time, agitation, initial dye concentration and carbon particle size range were also studied.

Gordon McKay

1979-01-01

223

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

2011-05-01

224

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. 458.40 Section... EFFLUENT GUIDELINES AND STANDARDS CARBON BLACK MANUFACTURING POINT SOURCE CATEGORY Carbon Black Lamp Process Subcategory § 458.40...

2010-07-01

225

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. 458.10 ...EFFLUENT GUIDELINES AND STANDARDS CARBON BLACK MANUFACTURING POINT SOURCE CATEGORY Carbon Black Furnace Process Subcategory § 458.10...

2010-07-01

226

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. 458.30 ...EFFLUENT GUIDELINES AND STANDARDS CARBON BLACK MANUFACTURING POINT SOURCE CATEGORY Carbon Black Channel Process Subcategory § 458.30...

2010-07-01

227

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. 458.20 ...EFFLUENT GUIDELINES AND STANDARDS CARBON BLACK MANUFACTURING POINT SOURCE CATEGORY Carbon Black Thermal Process Subcategory § 458.20...

2010-07-01

228

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

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.

Hopper, Robert W. (Danville, CA); Pekala, Richard W. (Pleasant Hill, CA)

1988-01-01

229

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

NASA Astrophysics Data System (ADS)

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

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

2012-07-01

230

Clinical and radiographic study of activated carbon workers.  

PubMed Central

Activated carbon is made in Sri Lanka by passing steam through charcoal made from coconut shells. The carbon does not contain free silica. Sixty six men who had worked in a factory making activated carbon for an average of 7.2 years had no more respiratory symptoms than a control group, and none showed radiological evidence of pneumoconiosis. There was no evidence that people exposed to charcoal and pure carbon for up to 11 years are at risk of developing pneumoconiosis. PMID:2763231

Uragoda, C G

1989-01-01

231

[Adsorption kinetics of reactive dyes on activated carbon fiber].  

PubMed

The adsorption capability of activated carbon fiber (ACF) to four reactive dyes (reactive brilliant red K-2BP, reactive turquoise blue KN-G, reactive golden yellow K-3RP, reactive black KN-B) in aqueous solution was studied, and adsorption mechanism was focused on from kinetics point of view. The results show that the equilibrium adsorbing capacity (q(e)) of each dye increases with the addition of initial concentration or temperature. On the same condition, the order of q(e) is: reactive brilliant red > reactive golden yellow > reactive black > reactive turquoise blue. The adsorption processes follow a pseudo second-order kinetic rate equation, and the steric structure, size and polarity of dyes are important influence factors to initial adsorption rate. The adsorption activation energy of each dye is low (16.42, 3.56, 5.21, 26.38 kJ x mol(-1) respectively), which indicates that it belongs to physics adsorption. PMID:18290496

Li, Ying; Yue, Qin-Yan; Gao, Bao-Yu; Yang, Jing; Zheng, Yan

2007-11-01

232

Activation-free printed carbon nanotube field emitters  

NASA Astrophysics Data System (ADS)

When a carbon nanotube paste is formulated based on highly functional hyperbranched polymers such as dipentaerythritol hexaacrylate, the volume shrinkage during thermal curing builds up internal stress that generates microcrack patterns on the printed surface. The nanotubes exposed in the cracks emit electrons successfully at such an extremely low electric field as 0.5 V µm - 1, and reach 25.5 mA cm - 2 of current density at 2 Vµm - 1 from an optimized paste concerning mainly the size and spatial uniformity of the crack. In addition to the superior field emission properties with low manufacturing cost, this activation-free technology can provide a minimized nanohazard in the device fabrication process, compared to those conventional activation technologies developing serious nanoflakes by using destructive methods.

Kim, Yong C.; Hur, Jung N.; Kim, Il H.; Park, Sang H.; Jung, Tae W.; Kim, Do Y.; Kim, Ha J.; Cha, Seung N.; Han, In T.; Kim, Jong M.; Kim, Young H.

2011-10-01

233

Carbonation of residual brines produced by ammonia-soda process  

NASA Astrophysics Data System (ADS)

This work deals with the carbonation of residual brines produced during the manufacture of soda ash to avoid the unsuitable phase transformation during the land storage. The study resulted in a demonstration pilot, which showed the feasibility of such an approach and the possibility of his extension to an industrial scale. Carbonation of the residual brines is a promising process as it entirely transforms Ca(OH)2, "CaOHCl" and CSH into calcite, avoids the further phase evolution, allows to obtain a neutral pH which considerably reduce the land storage impact on environment and shorten by around 10 % the global CO2 emission of the ammonia-soda process.

Filippova, I. V.; Piriou, P.; Filippov, L. O.; Yvon, J.; Grandjean, M.

2013-03-01

234

Iron-carbon compacts and process for making them  

DOEpatents

The present invention includes iron-carbon compacts and a process for making them. The process includes preparing a slurry comprising iron powder, furfuryl alcohol, and a polymerization catalyst for initiating the polymerization of the furfuryl alcohol into a resin, and heating the slurry to convert the alcohol into the resin. The resulting mixture is pressed into a green body and heated to form the iron-carbon compact. The compact can be used as, or machined into, a magnetic flux concentrator for an induction heating apparatus.

Sheinberg, Haskell (Santa Fe, NM)

2000-01-01

235

Carbon cycle. Sunlight controls water column processing of carbon in arctic fresh waters.  

PubMed

Carbon in thawing permafrost soils may have global impacts on climate change; however, the factors that control its processing and fate are poorly understood. The dominant fate of dissolved organic carbon (DOC) released from soils to inland waters is either complete oxidation to CO2 or partial oxidation and river export to oceans. Although both processes are most often attributed to bacterial respiration, we found that photochemical oxidation exceeds rates of respiration and accounts for 70 to 95% of total DOC processed in the water column of arctic lakes and rivers. At the basin scale, photochemical processing of DOC is about one-third of the total CO2 released from surface waters and is thus an important component of the arctic carbon budget. PMID:25146289

Cory, Rose M; Ward, Collin P; Crump, Byron C; Kling, George W

2014-08-22

236

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

237

Multi-physical field coupling simulation of TCVI process for preparing carbon\\/carbon composites  

Microsoft Academic Search

To prepare Carbon\\/Carbon (C\\/C) composites with advanced performance, the thermal gradient chemical vapor infiltration (TCVI)\\u000a process has been optimized by simulation. A 2D axisymmetric unstable model was built, which included convection, conduction,\\u000a diffusion, densification reactions in the pores and the evolution of the porous medium. The multi-physical field coupling\\u000a model was solved by finite element method (FEM) and iterative calculation.

YanQiong Jiao; HeJun Li; KeZhi Li

2009-01-01

238

Process Based Belowground Carbon Dioxide Modeling in a Desert Ecosystem  

NASA Astrophysics Data System (ADS)

We describe a study to integrate and assess biological and physical processes that govern belowground carbon dioxide levels at a semi-arid grassland near Canyonlands National Park. Carbon dioxide concentrations were measured every 30 minutes at 5 and 15 cm depth within the rooting zones of the two dominant grass species, Stipa hymenoides and Hilaria jamesii, as well as the interspace between the two. For Stipa hymenoides at 5 cm, a rain event caused belowground carbon dioxide levels to rise from 600 ppm to 2000 ppm with a response time of 8 hours, with a gradual return to quasi-steady state levels in subsequent days. A similar response was observed for H. jamesii. We developed and simulated a one-dimensional diffusion model with a production term for various types of CO2 production from the literature (either constant with increasing depth or a process based source). The process based production considered microbial and root respiration as well as the temperature dependence of soil respiration. Model inputs included volumetric soil water content, temperature and bulk density. Incorporating a process based production term led to high correlation between measured and modeled CO2 concentrations (r2 as high as 0.92). Our results indicate that carbon dioxide levels increased during rain events due to physical (not biological) processes as the soil saturated with water, and CO2 molecules diffused more slowly from the soil.

Zobitz, J. M.; Bowling, D. R.

2003-12-01

239

Effects of acidic treatment of activated carbons on dye adsorption  

Microsoft Academic Search

The effect of acidic treatments of activated carbons on dye adsorption was investigated. The physico-chemical properties of activated carbons were characterised by N2 adsorption, mass titration, temperature-programmed desorption (TPD), and X-ray photoelectron spectrometry (XPS). It was found that surface chemistry plays an important role in dye adsorption. HNO3 treatment produces more active acidic surface groups such as carboxyl and lactone,

Shaobin Wang; Z. H. Zhu

2007-01-01

240

Carbon processing in the Kolyma River Watershed and the role it plays in CO2 outgassing  

NASA Astrophysics Data System (ADS)

The Kolyma River watershed in Northeast Siberia is the largest watershed underlain by continuous permafrost, storing vast amounts of organic carbon and nutrients, which if thawed will become available to microbial processing or transport downstream. Understanding the internal hydrological processes and outgassing across large Arctic river watersheds is crucial if we are to better refine estimates of GHG emissions. Previous conceptual models treated waterways as simple pipes, transporting water from land to ocean without internal processing but current research makes it evident that we must acknowledge them as possible active processors. In July and August 2010, a survey spanning 260 km of the Kolyma River Watershed was conducted to examine the rates of carbon processing in a diverse set of subwatersheds. A total of 23 subwatersheds (eleven streams, and twelve rivers) and nine mainstem locations were sampled at which water samples were collected for measurements of partial pressure of Carbon dioxide (pCO2), dissolved organic carbon (DOC), chromophoric dissolved organic matter (CDOM) and biological oxygen demand (BOD). Spatially, pCO2 concentrations decrease along flowpaths from small streams to the Ocean with the greatest variation between small streams and large rivers. Measurements of DOC concentrations and bioavailability indicate small streams are higher in the total amount and lability of DOC compared to larger tributaries. The results of this study suggest the headwater streams in the Kolyma River watershed are actively processing carbon during the summer at a more significant rate compared to larger tributaries and the Kolyma mainstem. Understanding the relationship between watershed size and carbon processing is critical for predicting how future warming will likely impact the Arctic carbon cycle. This study is part of the Polaris Project, an NSF-funded undergraduate field program based out of the Northeast Science Station in Cherskiy, Northeast Siberia (www.thepolarisproject.org).

Denfeld, B. A.; Frey, K. E.; Bulygina, E. B.; Drake, T.; Holmes, R. M.; Schade, J. D.; Sobczak, W. V.; Zimov, N.

2010-12-01

241

Effects of activation method on the pore structure of activated carbons from apricot stones  

Microsoft Academic Search

Two series of activated carbons were prepared from apricot stones by using carbonization followed by steam activation and one-step pyrolysis\\/activation in steam. The pore structure of the activated carbons was characterized by CO2 adsorption at 273 K and by N2 adsorption at 77 K. The macro- and mesoporosity were determined by mercury porosimetry. Optical microscopy, scanning electron microscopy (SEM) and

K. Gergova; S. Eser

1996-01-01

242

Activated carbon fibers and engineered forms from renewable resources  

DOEpatents

A method of producing activated carbon fibers (ACFs) includes the steps of providing a natural carbonaceous precursor fiber material, blending the carbonaceous precursor material with a chemical activation agent to form chemical agent-impregnated precursor fibers, spinning the chemical agent-impregnated precursor material into fibers, and thermally treating the chemical agent-impregnated precursor fibers. The carbonaceous precursor material is both carbonized and activated to form ACFs in a single step. The method produces ACFs exclusive of a step to isolate an intermediate carbon fiber.

Baker, Frederick S

2013-02-19

243

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...

244

DETERMINATION OF DIOXIN LEVELS IN CARBON REACTIVATION PROCESS EFFLUENT STREAMS  

EPA Science Inventory

A preliminary study was performed to evaluate the potential formation and persistence of tetrachlorodibenzo-p-dioxins (TCDDs) and tetrachlorodibenzo furans (TCDFs) in the effluent streams of a fluidized bed system used for thermal reactivation of granular activated carbon (GAC) t...

245

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

246

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

247

TRIHALOMETHANE PRECURSOR REMOVAL BY THE MAGNESIUM CARBONATE PROCESS  

EPA Science Inventory

A project was conducted to determine and improve the ability of the magnesium carbonate process to remove trihalomethane (THM) precursors in treated drinking water. The project was conducted at a drinking water treatment plant in Melbourne, FL, which had been developed and instal...

248

Carbon dioxide–nitrogen separation through adsorption on activated carbon in a fixed bed  

Microsoft Academic Search

The reduction of carbon dioxide emissions from flue gases can be achieved using post-combustion capture technologies such as adsorption. In this paper, we report experimental data for the fixed-bed adsorption of carbon dioxide and nitrogen on activated carbon. The breakthrough curves were obtained at different temperatures – 301–306, 323, 373 and 423K – using CO2\\/N2 mixtures. XPS and FTIR measurements

Tirzhá L. P. Dantas; Francisco Murilo T. Luna; Ivanildo J. Silva Jr.; Diana C. S. de Azevedo; Carlos A. Grande; Alírio E. Rodrigues; Regina F. P. M. Moreira

2011-01-01

249

Processable high-carbon-yielding polymer for micro- and nanofabrication  

NASA Astrophysics Data System (ADS)

Bis-ortho-Diynyl Arene (BODA) monomers polymerize to network polynapthalene by the thermally-driven Bergman cyclization and subsequent radical polymerization via oligomeric intermediates that can be melt or solution processed. Further heating of the network to 1000 °C affords a high-yield glassy carbon structure that retains the approximate size and dimensions of the polymer precursor. The higher carbon-yield for BODA networks (75- 80 % by mass) is significantly greater than that of traditional phenol-formaldehyde resins and other carbon precursor polymers leading to its greater dimensional stability. Phenyl terminated BODA derived polymers were fabricated using microprocessing such as the micromolding in capillaries (MIMIC) technique, direct microtransfer molding, and molding in quartz capillary tubes. Nano-scale fabrication using closed packed silica spheres as templates was demonstrated with an hydroxy-terminated monomer which exhibits greatly enhanced compatibility for silica surfaces. After pyrolysis to glassy carbon, the silica is chemically etched leaving an inverse carbon opal photonic crystal which is electrically conductive. The wavelength of light diffracted is a function of the average refractive index of the carbon/ filler composite, which can be modified for use as sensitive detector elements.

Perpall, Mark W.; Zengin, Huseyin; Perera, K. Prasanna U.; Zhou, Wensheng; Shah, Hiren; Wu, Xinyu; Creager, Stephen E.; Smith, Dennis W., Jr.; Foulger, Stephen H.; Ballato, John M.

2003-01-01

250

Supporting information: ACTIVATED CARBON AND BIOCHAR AMENDMENTS DECREASE POREWATER  

E-print Network

Supporting information: ACTIVATED CARBON AND BIOCHAR AMENDMENTS DECREASE POREWATER CONCENTRATIONS of tables: 2 #12;Calculation of KAC/Kbiochar for sewage sludge with AC/biochar Sorption to AC in an AC as the measured distribution coefficients for unamended sediment normalized to sediment organic carbon content (Kd

Lehmann, Johannes

251

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...

252

SYNTHETIC ORGANIC CHEMICAL REMOVAL BY GRANULAR ACTIVATED CARBON  

EPA Science Inventory

The paper is an overview of the adsorbability of synthetic organic chemicals (SOC) by granular activated carbon (GAC). The paper demonstrates the adsorbability by presenting data on the removal of SOCs and organic surrogates such as total organic carbon and total organic halide b...

253

Activated carbon testing for the 200 area effluent treatment facility  

SciTech Connect

This report documents pilot and laboratory scale testing of activated carbon for use in the 200 Area Effluent Treatment Facility peroxide decomposer columns. Recommendations are made concerning column operating conditions and hardware design, the optimum type of carbon for use in the plant, and possible further studies.

Wagner, R.N.

1997-01-17

254

Semisolid processing of ultrahigh-carbon steel castings  

Microsoft Academic Search

Semi-solid processing using cooling plate technique was developed to produce a high quality ultrahigh-carbon steel (UHCS) components. Microstructure and mechanical properties were investigated as a function of fraction of solid. The microstructure of UHCS was improved using semi-solid processing. A unique homogenized microstructure comprised of fine particles grain size (200–100?m) was obtained which totally differs from that obtained by ordinary

Mohamed Ramadan; Mitsuharu Takita; Hiroyuki Nomura; Nader El-Bagoury

2006-01-01

255

Removal of phenols from water environment by activated carbon, bagasse ash and wood charcoal  

Microsoft Academic Search

Adsorption process is gaining interest as one of the effective processes of advanced wastewater treatment for treatment of industrial effluent containing toxic materials. The present work involves an investigation of the use of three carbonaceous materials, activated carbon (AC), bagasse ash (BA) and wood charcoal (WC), as adsorbents for removal of phenol from water. Batch experiments were carried out to

Somnath Mukherjee; Sunil Kumar; Amal K. Misra; Maohong Fan

2007-01-01

256

Catalytic methods in coal processing to syn-gas, carboneous and liquid fuels contributing to sustainable development  

Microsoft Academic Search

The processes of brown coal autothermal carbonization and steam gasification in a fluidized bed of catalytically active materials, catalytic hydrogenation of brown coal and its mixtures with waste polyolefines and sapropelitic coal liquefaction have been studied. The application of fluidized bed of iron-containing materials, which are able to catalyse the volatives oxidation provides the autothermal conditions of coal carbonization without

B. N. Kuznetsov

2009-01-01

257

Selection and preparation of activated carbon for fuel gas storage  

DOEpatents

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

Schwarz, James A. (Fayetteville, NY); Noh, Joong S. (Syracuse, NY); Agarwal, Rajiv K. (Las Vegas, NV)

1990-10-02

258

Supporting the Active Learning Process  

ERIC Educational Resources Information Center

Many e-learning materials lack pedagogical principles and theoretical foundations. The great potential of activating learners and thus enriching learning experience is often unused in instructional software and online courses. Pedagogical theories like constructivist and action-orientated approaches should rather underlie the creation of new…

Schroeder, Ulrik; Spannagel, Christian

2006-01-01

259

Quality of poultry litter-derived granular activated carbon.  

PubMed

Utilization of poultry litter as a source material for generating activated carbon is a value-added and environmentally beneficial approach to recycling organic waste. In this study, the overall quality of poultry litter-derived granular activated carbon was systematically evaluated based on its various physical and chemical properties. Granular activated carbon generated from pelletized poultry litter following a typical steam-activation procedure possessed numerous micropores in the matrix. The product exhibited a mean particle diameter of 2.59 mm, an apparent density of 0.45 g cm(-3), a ball-pan hardness of 91.0, an iodine number of 454 mg g(-1), and a BET surface area of 403 m(2) g(-1). It contained high ash, nitrogen, phosphorus contents and the trace elements Cu, Zn, and As. Most of the nutrients and toxic elements were solidified and solution-unextractable. In general, poultry litter-based activated carbon demonstrated overall quality comparable to that of low-grade commercial activated carbon derived from coconut shell and bituminous coal. It is promising to use poultry litter as a feedstock to manufacture activated carbon for wastewater treatment. PMID:19703765

Qiu, Guannan; Guo, Mingxin

2010-01-01

260

Natural gas storage with activated carbon from a bituminous coal  

USGS Publications Warehouse

Granular activated carbons ( -20 + 100 mesh; 0.149-0.84 mm) were produced by physical activation and chemical activation with KOH from an Illinois bituminous coal (IBC-106) for natural gas storage. The products were characterized by BET surface area, micropore volume, bulk density, and methane adsorption capacities. Volumetric methane adsorption capacities (Vm/Vs) of some of the granular carbons produced by physical activation are about 70 cm3/cm3 which is comparable to that of BPL, a commercial activated carbon. Vm/Vs values above 100 cm3/cm3 are obtainable by grinding the granular products to - 325 mesh (<0.044 mm). The increase in Vm/Vs is due to the increase in bulk density of the carbons. Volumetric methane adsorption capacity increases with increasing pore surface area and micropore volume when normalizing with respect to sample bulk volume. Compared with steam-activated carbons, granular carbons produced by KOH activation have higher micropore volume and higher methane adsorption capacities (g/g). Their volumetric methane adsorption capacities are lower due to their lower bulk densities. Copyright ?? 1996 Elsevier Science Ltd.

Sun, J.; Rood, M. J.; Rostam-Abadi, M.; Lizzio, A. A.

1996-01-01

261

Use of Unburned Carbon in Fly Ash as Precursor for the Development of Activated Carbons  

Microsoft Academic Search

The increasing role of coal as a source of energy in the 21st century will demand environmental and cost-effective strategies for the use of carbonaceous waste products from coal combustion. The carbonaceous residue in fly ash, unburned carbon (UC), is a potential precursor for the production of adsorbent carbons, since it has gone through a devolatilization process while in the

M. Mercedes Maroto-Valer; Darrell N. Taulbee; Harold H. Schobert; James C. Hower; John M. Andrésen

262

76 FR 58246 - Certain Activated Carbon From the People's Republic of China: Notice of Partial Rescission of...  

Federal Register 2010, 2011, 2012, 2013

...Carbon Plant; Ningxia Guanghua A/C Co., Ltd.; Ningxia Blue-White-Black Activated Carbon (BWB); Ningxia Fengyuan...Activated Carbon; Shanghai Xingchang Activated Carbon; Shanxi Blue Sky Purification Material Co., Ltd.; Shanxi Carbon...

2011-09-20

263

Carbonate-free inorganic nitrates or oxides and process thereof  

SciTech Connect

This patent describes an improved process to produce an essentially carbon-free nitrate independently selected from an alkali metal, alkaline earth metal, transition metal, lanthanide metal actinide metal, or mixtures thereof. It comprises contacting an essentially anhydrous composition of an alkali metal, alkaline earth metal, transition metal, lanthanum metal, actinide metal, or mixtures thereof at least one of which are substituted with an organic or an inorganic carbon-containing substituent; with flowing nitrogen dioxide, dinitrogen tetroxide or mixtures thereof at a temperature of between about 100{degrees} to 150{degrees} C.

Gusman, M.; Tong, G.; Sanjurjo, A.; Johnson, S.M.; Lamoreaux, R.

1992-06-16

264

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

PubMed

Porous carbon has been prepared from waste antibiotic material by a chemical activation method using K(2)CO(3) 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 to produce microporous activated carbon with a micropore volume up to 0.492 cm(3)/g and a BET surface area of 1260 m(2)/g. Adsorption of mercury(II) from an aqueous solution on antibiotic carbon was investigated under the varying conditions of agitation time, metal ion concentration and pH. The adsorption capacity of the carbon is 129 mg/g. PMID:17428604

Budinova, Temenuzhka; Petrov, Nartzislav; Parra, Jose; Baloutzov, Venelin

2008-07-01

265

GROWTH AND PERSISTENCE OF PATHOGENS ON GRANULAR ACTIVATED CARBON FILTERS  

EPA Science Inventory

Three enteric pathogens Yersinia enterocolitica 0:8, Salmonella typhimurium, and enterotoxigenic Escherichia coli, were examined for their ability to colonize granular activated carbon (GAC) in pure cultures and in the presence of autochthonous river water organisms. All three or...

266

GRANULAR ACTIVATED CARBON ADSORPTION AND INFRARED REACTIVATION: A CASE STUDY  

EPA Science Inventory

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

267

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

268

Solution-processed soldering of carbon nanotubes for flexible electronics.  

PubMed

We report a simple lithography-free, solution-based method of soldering of carbon nanotubes with Ohmic contacts, by taking specific examples of multi-walled carbon nanotubes (MWNTs). This is achieved by self-assembling a monolayer of soldering precursor, Pd(2+) anchored to 1,10 decanedithiol, onto which MWNTs could be aligned across the gap electrodes via solvent evaporation. The nanosoldering was realized by thermal/electrical activation or by both in sequence. Electrical activation and the following step of washing ensure selective retention of MWNTs spanning across the gap electrodes. The soldered joints were robust enough to sustain strain caused during the bending of flexible substrates as well as during ultrasonication. The estimated temperature generated at the MWNT-Au interface using an electro-thermal model is ?150?°C, suggesting Joule heating as the primary mechanism of electrical activation. Further, the specific contact resistance is estimated from the transmission line model. PMID:23358531

Rao, K D M; Radha, B; Smith, K C; Fisher, T S; Kulkarni, G U

2013-02-22

269

Moisture processes accompanying convective activity  

E-print Network

- dicated by the synoptic-scale moisture convergence. Scott and Scoggins (1977) analyzed the moisture budget for two squall lines that occurred during the Spring of 1975. By using ob- servations spaced at 3 and 6 hr, they found that moisture accumu..., and the entire system, along with its associated convective activity, moved eastward with time. 15 4. THEORETICAL DEVELOPMENT OF THE MOISTURE BUDGET EQUATION Scott and Scoggins (1977) used a moisture budget equation sim- ilar to the one used in this research...

Sienkiewicz, Meta Elizabeth

2012-06-07

270

Porosity in granular carbons activated with phosphoric acid  

Microsoft Academic Search

Three series of activated carbon have been prepared by heat treatment of peach stones impregnated with solutions of phosphoric acid, in order to analyze the effect of phosphoric acid on the yield, bulk density and porosity of the resultant activated carbons. The analysis of the adsorption isotherms of N2 at 77 K. CO2 at 273 K and n-C4H10, at 273

M. Molina-Sabio; F. RodRíguez-Reinoso; F. Caturla; M. J. Sellés

1995-01-01

271

Setup for Visual Observation of Carbon-Nanotube Arc Process  

NASA Technical Reports Server (NTRS)

A simple optical setup has been devised to enable safe viewing of the arc and measurement of the interelectrode gap in a process in which carbon nanotubes are produced in an arc between a catalyst-filled carbon anode and a graphite cathode. This setup can be used for visually guided manual positioning of the anode to maintain the interelectrode gap at a desired constant value, possibly as a low-technology alternative to the automatic position/voltage control described in Automatic Control of Arc Process for Making Carbon Nanotubes (MSC-23134), NASA Tech Briefs, Vol. 28, No. 3 (March 2004), page 51. The optical setup consists mainly of lenses for projecting an image of the arc onto a wall, plus a calibrated grid that is mounted on the wall so that one can measure the superimposed image of the arc. To facilitate determination of the end point of the process, the anode is notched, by use of a file, at the end of the filled portion that is meant to be consumed in the process. As the anode is consumed and the notch comes into view in the scene projected onto the wall, the process operator switches off the arc current.

Scott, Carl D.; Arepalli, Sivaram

2004-01-01

272

Carbon Nanotube Materials for Substrate Enhanced Control of Catalytic Activity  

SciTech Connect

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

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

2007-05-01

273

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

NASA Astrophysics Data System (ADS)

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

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

2009-07-01

274

Treatment of olive mill waste water with activated carbons from agricultural by-products.  

PubMed

A series of activated carbons prepared by a two-step steam activation of olive stone and solvent extracted olive pulp (SEOP) have been used in an attempt to investigate the total phenol removal and chemical oxygen demand (COD) decrease in olive mill waste water (OMWW). The temperature of carbonization and activation were kept constant at 850 and 800 degrees C, respectively. One of the carbons was prepared by a single-step process at 800 degrees C. Activated carbons have been characterized by adsorption of N2 at 77 K and mercury porosimetry. Their iodine values were also determined. Surface oxides of activated carbons were determined using the Boehm's method. The porosity development and the surface chemistry of carbons were correlated to increasing removal ability of organic molecules. Kinetics of adsorption was evaluated by applying the Lagegren model while adsorption isotherm data were fitted to Langmuir model. Mesoporosity seems to be the key factor for total phenol removal while micoporosity controls the adsorption of total organics as expressed by the COD decrease in OMWW. For carbons with similar structure, the adsorption of phenols or total organics might be affected by the presence of carbonyls. PMID:12365783

Galiatsatou, Polymnia; Metaxas, Michail; Arapoglou, Dimitrios; Kasselouri-Rigopoulou, Vasilia

2002-01-01

275

REMOVAL OF ORGANIC POLLUTANTS FROM SUBCRITICAL WATER WITH ACTIVATED CARBON  

SciTech Connect

The Energy & Environmental Research Center (EERC) has demonstrated that controlling the temperature (and to a lesser extent, the pressure) of water can dramatically change its ability to extract organics and inorganics from matrices ranging from soils and sediments to waste sludges and coal. The dielectric constant of water can be changed from about 80 (a very polar solvent) to <5 (similar to a nonpolar organic solvent) by controlling the temperature (from ambient to about 400 C) and pressure (from about 5 to 350 bar). The EERC has shown that hazardous organic pollutants such as pesticides, PACS (polycyclic aromatic hydrocarbons), and PCBs (polychlorinated biphenyls) can be completely removed from soils, sludges, and sediments at temperatures (250 C) and pressures (<50 atm) that are much milder than typically used for supercritical water processes (temperature >374 C, pressure >221 atm). In addition, the process has been demonstrated to be particularly effective for samples containing very high levels of contaminants (e.g., part per thousand). Current projects include demonstrating the subcritical water remediation process at the pilot scale using an 8-liter system constructed under separate funding during 1997. To date, subcritical water has been shown to be an effective extraction fluid for removing a variety of organic pollutants from soils and sludges contaminated with fossil fuel products and waste products, including PACS from soil (e.g., town gas sites), refining catalysts, and petroleum tank bottom sludges; PCBs from soil and sediments; toxic gasoline components (e.g., benzene) from soil and waste sludge; and phenols from petroleum refinery sludges. The obvious need to clean the wastewater from subcritical water processes led to preliminary experiments with activated carbon placed in line after the extractor. Initial experiments were performed before and after cooling the extractant water (e.g., with water at 200 C and with water cooled to 25 C). Surprisingly, the ability of activated carbon to remove organics from the water is better at a high temperature than at room temperature. These initial results are opposite to those expected from chromatographic theory, since the solubility of the organics is about 100,000-fold higher in the hot water than in ambient water. At present, the physicochemical mechanism accounting for these results is unknown; however, it is possible that the lower surface tension and lower viscosity of subcritical water (compared to water at ambient conditions) greatly increases the available area of the carbon by several orders of magnitude. Regardless of the mechanism involved, the optimal use of activated carbon to clean the wastewater generated from subcritical water remediation will depend on obtaining a better understanding of the controlling parameters. While these investigations focused on the cleanup of wastewater generated from subcritical water remediation, the results also apply to cleanup of any wastewater contaminated with nonpolar and moderately polar organics such as wastewaters from coal and petroleum processing.

Steven B. Hawthorne; Arnaud J. Lagadec

1999-08-01

276

High grade activated carbon matting derived from the chemical activation and pyrolysis of natural fibre textile waste  

Microsoft Academic Search

Waste generated as a by-product of the production and use of natural fibres in the textile industry is typically over 50wt.% and is normally landfilled. In this research, flax and hemp natural fibres have been manufactured into a non-woven, pre-formed matting material and subsequently treated via chemical activation and pyrolysis to produce activated carbon. The influence of chemical activation process

Paul T. Williams; Anton R. Reed

2004-01-01

277

Analysis of structure and properties of active carbons and their copolymeric precursors  

NASA Astrophysics Data System (ADS)

The relations between chemical structures of BM-DVB copolymers obtained with various monomer molar ratios and their carbonization products were studied. Three porous copolymers 1:4, 1:1, and 4:1 of BM to DVB were the starting materials for preparation of active carbons. Two activation agents were employed: air and phosphoric acid. The carbonization process was performed in the same way in these two cases. To characterize the obtained materials FTIR spectroscopy, thermal and elemental analyses were applied. Porous structure parameters were obtained by means of nitrogen sorption. The results proved that differences in the molar ratio of monomers used in the syntheses of polymeric precursor play a key role for structure and properties of copolymers but have rather small influence on properties of the obtained carbons. Preliminary treatment is more effective during the activation process. The carbons obtained by activation with phosphoric acid are microporous and have well developed porous structures. The air activated carbons are mesoporous with specific surface areas similar to those of polymeric precursors.

Sobiesiak, M.; Gawdzik, B.; Puziy, A. M.; Poddubnaya, O. I.

2010-06-01

278

Moisture processes accompanying convective activity  

NASA Technical Reports Server (NTRS)

A moisture budget analysis was performed on data collected during the AVE 7 (May 2 to 3, 1978) and AVE-SESAME1 (April 10 to 11, 1979) experiments. Local rates-of-change of moisture were compared with average moisture divergence in the same time period. Results were presented as contoured plots in the horizontal and as vertical cross sections. These results were used to develop models of the distribution of moisture processes in the vicinity of convective areas in two layers representing lower and middle tropospheric conditions. Good correspondence was found between the residual term of the moisture budget and actual precipitation.

Sienkiewicz, M. E.; Scoggins, J. R.

1982-01-01

279

Converting poultry litter to activated carbon: optimal carbonization conditions and product sorption for benzene  

Microsoft Academic Search

To promote utilization of poultry litter as a source material for manufacturing low-cost activated carbon (AC) that can be used in wastewater treatment, this study investigated optimal production conditions and water-borne organic sorption potential of poultry litter-based AC. Pelletized broiler litter was carbonized at different temperatures for varied time periods and activated with steam at a range of flow rate

Mingxin Guo; Weiping Song

2011-01-01

280

Processes determining the marine alkalinity and carbonate saturation distributions  

NASA Astrophysics Data System (ADS)

We introduce a composite tracer, Alk*, that has a global distribution primarily determined by CaCO3 precipitation and dissolution. Alk* also highlights riverine alkalinity plumes that are due to dissolved calcium carbonate from land. We estimate the Arctic receives approximately twice the riverine alkalinity per unit area as the Atlantic, and 8 times that of the other oceans. Riverine inputs broadly elevate Alk* in the Arctic surface and particularly near river mouths. Strong net carbonate precipitation lowers basin mean Indian and Atlantic Alk*, while upwelling of dissolved CaCO3 rich deep waters elevates Northern Pacific and Southern Ocean Alk*. We use the Alk* distribution to estimate the carbonate saturation variability resulting from CaCO3 cycling and other processes. We show regional variations in surface carbonate saturation are due to temperature changes driving CO2 fluxes and, to a lesser extent, freshwater cycling. Calcium carbonate cycling plays a tertiary role. Monitoring the Alk* distribution would allow us to isolate the impact of acidification on biological calcification and remineralization.

Carter, B. R.; Toggweiler, J. R.; Key, R. M.; Sarmiento, J. L.

2014-07-01

281

Benign reduction of carbon nanotube agglomerates using a supercritical carbon dioxide process  

NASA Astrophysics Data System (ADS)

A method was developed to deagglomerate commercially available multi-walled carbon nanotube (MWCNT) bundles while maintaining the carbon nanotube aspect ratio. The process utilizes the rapid expansion of a supercritical carbon dioxide/MWCNT mixture to separate large primary carbon nanotube agglomerates. High levels of deagglomeration of Baytubes® C 150 P and Nanocyl™ NC-7000 MWCNT bundles were observed on the macroscale and nanoscale, resulting in 30-fold and 50-fold decreases in bulk density, respectively, with median agglomerate sizes <8 ?m in diameter. These results were obtained while retaining the aspect ratio of the as-received nanomaterial, irrespective of the MWCNT agglomerate morphology. It was found that a temperature and pressure of 40 °C and 7.86 MP resulted in maximum deagglomeration without damage to the MWCNTs. Thermodynamic principles were applied to describe the effect of processing variables on the efficiency of the deagglomeration. These results suggest that combining this process with a composite processing step, such as melt compounding, will result in nanocomposites with enhanced electrical properties.

Quigley, John P.; Herrington, Kevin; Bortner, Michael; Baird, Donald G.

2014-09-01

282

Kinetics of Processes Distributed in Activation Energy  

Microsoft Academic Search

The kinetic behavior of systems in which processes occur which are distributed over a range of activation energies is considered. The effects produced by the initial distribution, the order of reaction, and the frequency factor are discussed. Imaginary and actual experimental situations are used to illustrate the large errors which can result when the distribution of the processes in activation

W. Primak

1955-01-01

283

Extraordinary hydrogen evolution and oxidation reaction activity from carbon nanotubes and graphitic carbons.  

PubMed

The hydrogen evolution reaction, 2H(+) + 2e(–) ? H2, and its converse, the hydrogen oxidation reaction, H2 ? 2H(+) + 2e(–), are central to any realization of a hydrogen economy. Various forms of carbon have been used for decades as the precious metal catalyst support in these reactions. Here we report the unexpected result that single-wall carbon nanotubes and some graphitic carbons, activated by brief exposure to electrochemical potentials that induce hydrogen evolution in intercalating acids combined with extended soak times in such acids, acquire an activity for these reactions that exceeds that of known nonprecious metal catalysts. PMID:25017805

Das, Rajib Kumar; Wang, Yan; Vasilyeva, Svetlana V; Donoghue, Evan; Pucher, Ilaria; Kamenov, George; Cheng, Hai-Ping; Rinzler, Andrew G

2014-08-26

284

Process for preparing tapes from thermoplastic polymers and carbon fibers  

NASA Technical Reports Server (NTRS)

The instant invention involves a process for use in preparing tapes or rovings, which are formed from a thermoplastic material used to impregnate longitudinally extended bundles of carbon fibers. The process involves the steps of (a) gas spreading a tow of carbon fibers; (b) feeding the spread tow into a crosshead die; (c) impregnating the tow in the die with a thermoplastic polymer; (d) withdrawing the impregnated tow from the die; and (e) gas cooling the impregnated tow with a jet of air. The crosshead die useful in the instant invention includes a horizontally extended, carbon fiber bundle inlet channel, means for providing melted polymer under pressure to the die, means for dividing the polymeric material flowing into the die into an upper flow channel and a lower flow channel disposed above and below the moving carbon fiber bundle, means for applying the thermoplastic material from both the upper and lower channels to the fiber bundle, and means for withdrawing the resulting tape from the die.

Chung, Tai-Shung (Inventor); Furst, Howard (Inventor); Gurion, Zev (Inventor); McMahon, Paul E. (Inventor); Orwoll, Richard D. (Inventor); Palangio, Daniel (Inventor)

1986-01-01

285

Hydrogenation of ortho-nitrochlorobenzene on activated carbon supported platinum catalysts  

PubMed Central

Platinum/carbon catalyst is one of the most important catalysts in hydrogenation of ortho-nitrochlorobenzene to 2,2?-dichlorohydrazobenzene. The preparation process and the supports of catalysts are studied in this paper. Raw materials and preparation procedure of the activated carbon have great influences on the compositions and surface structure of platinum/carbon catalysts. Platinum catalysts supported on activated carbon with high purity, high surface area, large pore volume and appropriate pore structure usually exhibit higher activities for hydrogenation of ortho-nitrochlorobenzene to 2,2?-dichlorohydrazobenzene. The catalyst prepared from H2PtCl6 with pH=3 shows greater catalytic performance than those prepared under other conditions. PMID:15822151

Jiang, Cheng-jun; Yin, Hong; Chen, Zhi-rong

2005-01-01

286

Processing and thermal properties of filament wound carbon-carbon composites for impact shell application  

NASA Astrophysics Data System (ADS)

The performance and safety of the radioisotope power source depend in part on the thermal and impact properties of the materials used in the general purpose heat source (GPHS) through the use of an impact shell, thermal insulation and an aeroshell. Results from an earlier study indicate the importance of circumferential fibers to the mechanical properties of cylindrical filament wound carbon-carbon composites for the impact shell application. Based on this study, an investigation was initiated to determine the processing characteristics and the mechanical and thermal response of three filament wound configurations with different percentages of circumferential fibers: 50%, 66% and 80%. The performs were fabricated using a 3-D filament winding machine followed by five cycles of resin impregnation and carbonization. In this paper, the processing sequence and the resulting microstructures of the composites will be described. The thermal conductivity values of the composites as a function of fiber configuration and density will be discussed. These results will be compared with the fine-weave pierced-fabric (FWPF) material and carbon-bonded carbon-fiber insulation. Finally, the relevance of the new configurations for applications in the general purpose heat source (GPHS) will also be inferred. .

Zee, Ralph; Romanoski, Glenn; Gale, H. Shyam; Wang, Hsin

2001-02-01

287

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; Madhavi Nallani-Chakravartula; Peter G. Stansberry; Alfred H. Stiller; John W. Zondlo

2006-03-27

288

Detection of low concentration oxygen containing functional groups on activated carbon fiber surfaces through fluorescent labeling  

E-print Network

carbon, activated carbon fibers and carbon nano- tubes, are based on the presence of oxygen containingDetection of low concentration oxygen containing functional groups on activated carbon fiber of surface functional groups (OH, COOH and CHO) on activated carbon fiber surfaces. The chromophores were

Borguet, Eric

289

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

290

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.

291

Comparing Sulfur and Carbon Speciation in Ophiolites and Active Peridotite-hosted Hydrothermal Systems  

NASA Astrophysics Data System (ADS)

At slow and ultraslow mid-oceanic ridges, tectonic extension and crustal thinning lead to the exposure of ultramafic rocks on the ocean floor resulting in serpentinization and precipitation of carbonates in open fractures. Serpentinization processes play a major role in the global marine bio-geochemical cycle and account for an important part of the exchange of sulfur and carbon between seawater and the oceanic crust. The opaque mineral assemblages and the sulfur and carbon isotopic compositions of the serpentinites strongly depend on fluid flux, redox conditions and microbial activity prevailing during serpentinization. Here we present a carbon and sulfur geochemical study that compares Lost City, the only as yet known active peridotite-hosted hydrothermal system, with ancient systems preserved in drill cores of the Iberian margin (ODP Leg 149) and ophicalcites from Liguria (northern Apennines, Italy). Carbon speciation and isotope analyses conducted on serpentinized peridotites from Leg 149 show distinct changes with depth, indicating a decrease in seawater penetration and marine carbonate precipitation downhole, but constant precipitation temperatures of <20°C. Samples from Liguria show similar marine carbon isotope values, but higher carbonate precipitation temperatures (<144°C), which are in the range of serpentinization temperatures measured at the Iberian Margin (~150°C). Values of ?13CTOC suggest the presence of organic matter and lie within a narrow range of -28 to -24 permil at both localities. The occurrence of magnetite, pyrite, pentlandite and millerite in serpentinites from Liguria are similar to the opaque mineral assemblages observed by Alt and Shanks [1] in samples from the Iberian Margin, where serpentinization took place at low temperatures (<200°C) and high water-rock ratios. In addition, they are very similar to assemblages in serpentinite samples from the southern wall at the Atlantis Massif, where microbial activity below active hydrothermal chimneys is indicated by negative ?34S-values. The range in carbon compositions and a dominance of depleted carbon isotope compositions is similar to trends in serpentinites from Lost City and indicates that organic carbon is an important component of the carbon budget in marine serpentinites. Furthermore, carbon and sulfur isotope compositions indicate that microbial activity has a significant influence on the development of active and ancient peridotite-hosted hydrothermal systems. [1] Alt, J. C. and Shanks, W. C. 1998: Sulfur in serpentinized oceanic peridotites: Serpentinization processes and microbial sulfate reduction. Journal of geophysical research 103, B5, 9917- 9929.

Schwarzenbach, E. M.; Frueh-Green, G. L.; Bernasconi, S. M.; Delacour, A.; Plas, A.

2008-12-01

292

Carbon monoxide activates autophagy via mitochondrial reactive oxygen species formation.  

PubMed

Autophagy, an autodigestive process that degrades cellular organelles and protein, plays an important role in maintaining cellular homeostasis during environmental stress. Carbon monoxide (CO), a toxic gas and candidate therapeutic molecule, confers cytoprotection in animal models of acute lung injury. The mechanisms underlying CO-dependent lung cell protection and the role of autophagy in this process remain unclear. Here, we demonstrate that CO exposure time-dependently increased the expression and activation of the autophagic protein, microtubule-associated protein-1 light chain-3B (LC3B) in mouse lung, and in cultured human alveolar (A549) or human bronchial epithelial cells. Furthermore, CO increased autophagosome formation in epithelial cells by electron microscopy and green fluorescent protein (GFP)-LC3 puncta assays. Recent studies indicate that reactive oxygen species (ROS) play an important role in the activation of autophagy. CO up-regulated mitochondria-dependent generation of ROS in epithelial cells, as assayed by MitoSOX fluorescence. Furthermore, CO-dependent induction of LC3B expression was inhibited by N-acetyl-L-cysteine and the mitochondria-targeting antioxidant, Mito-TEMPO. These data suggest that CO promotes the autophagic process through mitochondrial ROS generation. We investigated the relationships between autophagic proteins and CO-dependent cytoprotection using a model of hyperoxic stress. CO protected against hyperoxia-induced cell death, and inhibited hyperoxia-associated ROS production. The ability of CO to protect against hyperoxia-induced cell death and caspase-3 activation was compromised in epithelial cells infected with LC3B-small interfering (si)RNA, indicating a role for autophagic proteins. These studies uncover a new mechanism for the protective action of CO, in support of potential therapeutic application of this gas. PMID:21441382

Lee, Seon-Jin; Ryter, Stefan W; Xu, Jin-Fu; Nakahira, Kiichi; Kim, Hong Pyo; Choi, Augustine M K; Kim, Young Sam

2011-10-01

293

[Biogeochemical processes of the major ions and dissolved inorganic carbon in the Guijiang River].  

PubMed

Within the drainage basin, information about natural processes and human activities can be recorded in the chemical composition of riverine water. The analysis of the Guijiang River, the first level tributary of the Xijiang River, demonstrated that the chemical composition of water in the Guijiang River was mainly influenced by the chemical weathering of carbonate rocks within the drainage basin, in which CO2 was the main erosion medium, and that the weathering of carbonate rock by H2SO4 had a remarkable impact on the water chemical composition in the Guijiang River. Precipitation, human activities, the weathering of carbonate rocks and silicate rocks accounted for 2.7%, 6.3%, 72.8% and 18.2% of the total dissolved load, respectively. The stable isotopic compositions of dissolved inorganic carbon (delta13C(DIC)) indicated that DIC in the Guijiang River had been assimilated by the phytoplankton in photosynthesis. The primary production of phytoplankton contributed to 22.3%-30.9% of particulate organic carbon (POC) in the Guijiang River, which implies that phytoplankton can transform DIC into POC by photosynthesis, and parts of POC will sink into the bottom of the river in transit, which leads into the formation of burial organic carbon. PMID:25158483

Tang, Wen-Kui; Tao, Zhen; Gao, Quan-Zhou; Mao, Hai-Ruo; Jiang, Guang-Hui; Jiao, Shu-Lin; Zheng, Xiong-Bo; Zhang, Qian-Zhu; Ma, Zan-Wen

2014-06-01

294

Computational Tools for Accelerating Carbon Capture Process Development  

SciTech Connect

The goals of the work reported are: to develop new computational tools and models to enable industry to more rapidly develop and deploy new advanced energy technologies; to demonstrate the capabilities of the CCSI Toolset on non-proprietary case studies; and to deploy the CCSI Toolset to industry. Challenges of simulating carbon capture (and other) processes include: dealing with multiple scales (particle, device, and whole process scales); integration across scales; verification, validation, and uncertainty; and decision support. The tools cover: risk analysis and decision making; validated, high-fidelity CFD; high-resolution filtered sub-models; process design and optimization tools; advanced process control and dynamics; process models; basic data sub-models; and cross-cutting integration tools.

Miller, David

2013-01-01

295

Growth processes and surface properties of diamondlike carbon films  

NASA Astrophysics Data System (ADS)

In this study, we compare the deposition processes and surface properties of tetrahedral amorphous carbon (ta-C) films from filtered pulsed cathodic arc discharge (PCAD) and hydrogenated amorphous carbon (a-C:H) films from electron cyclotron resonance (ECR)-plasma source ion implantation. The ion energy distributions (IEDs) of filtered-PCAD at various filter inductances and Ar gas pressures were measured using an ion energy analyzer. The IEDs of the carbon species in the absence of background gas and at low gas pressures are well fitted by shifted Maxwellian distributions. Film hardness and surface properties show a clear dependence on the IEDs. ta-C films with surface roughness at an atomic level and thin (0.3-0.9 nm) graphitelike layers at the film surfaces were deposited at various filter inductances in the highly ionized plasmas with the full width at half maximum ion energy distributions of 9-16 eV. The a-C:H films deposited at higher H /C ratios of reactive gases were covered with hydrogen and sp3 bonded carbon-enriched layers due to the simultaneous interaction of hydrocarbon species and atomic hydrogen. The effects of deposited species and ion energies on film surface properties were analyzed. Some carbon species have insufficient energies to break the delocalized ?(nC ) bonds at the graphitelike film surface, and they can govern film formation via surface diffusion and coalescence of nuclei. Dangling bonds created by atomic hydrogen lead to uniform chemisorption of hydrocarbon species from the ECR plasmas. The deposition processes of ta-C and a-C:H films are discussed on the basis of the experimental results.

Liu, Dongping; Zhang, Jialiang; Liu, Yanhong; Xu, Jun; Benstetter, Günther

2005-05-01

296

Preparation of activated carbon from wet sludge by electrochemical-NaClO activation.  

PubMed

Activated carbon (AC) from sludge is one potential solution for sewage sludge disposal, while the drying sludge is cost and time consuming for preparation. AC preparation from the wet sludge with electrochemical-NaClO activation was studied in this work. Three pretreatment processes, i.e. chemical activation, electrolysis and electrochemical-reagent reaction, were introduced to improve the sludge-derived AC properties, and the optimum dosage of reagent was tested from the 0.1:1 to 1:1 (mass rate, reagent:dried sludge). It was shown that the electrochemical-NaClO preparation is the best method under the test conditions, in which AC has the maximum Brunauer, Emmett and Teller area of 436 m(2)/g at a mass ratio of 0.7. Extracellular polymeric substances in sludge can be disintegrated by electrochemical-NaClO pretreatment, with a disintegration degree of more than 45%. The percentage of carbon decreased from 34.16 to 8.81 after treated by electrochemical-NaClO activation. Fourier transform infrared spectra showed that a strong C-Cl stretching was formed in electrochemical-NaClO prepared AC. The maximum adsorption capacity of AC reaches 109 mg/g on MB adsorption experiment at pH 10 and can be repeated for three times with high removal efficiency after regeneration. PMID:25176302

Miao, Chen; Ye, Caihong; Zhu, Tianxing; Lou, Ziyang; Yuan, Haiping; Zhu, Nanwen

2014-01-01

297

Granular bamboo-derived activated carbon for high CO(2) adsorption: the dominant role of narrow micropores.  

PubMed

Cost-effective biomass-derived activated carbons with a high CO(2) adsorption capacity are attractive for carbon capture. Bamboo was found to be a suitable precursor for activated carbon preparation through KOH activation. The bamboo size in the range of 10-200 mesh had little effect on CO(2) adsorption, whereas the KOH/C mass ratio and activation temperature had a significant impact on CO(2) adsorption. The bamboo-derived activated carbon had a high adsorption capacity and excellent selectivity for CO(2) , and also the adsorption process was highly reversible. The adsorbed amount of CO(2) on the granular activated carbon was up to 7.0 mmol g(-1) at 273 K and 1 bar, which was higher than almost all carbon materials. The pore characteristics of activated carbons responsible for high CO(2) adsorption were fully investigated. Based on the analysis of narrow micropore size distribution of several activated carbons prepared under different conditions, a more accurate micropore range contributing to CO(2) adsorption was proposed. The volume of micropores in the range of 0.33-0.82 nm had a good linear relationship with CO(2) adsorption at 273 K and 1 bar, and the narrow micropores of about 0.55 nm produced the major contribution, which could be used to evaluate CO(2) adsorption on activated carbons. PMID:23132775

Wei, Haoran; Deng, Shubo; Hu, Bingyin; Chen, Zhenhe; Wang, Bin; Huang, Jun; Yu, Gang

2012-12-01

298

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...

299

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

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

300

Regeneration of granular activated carbon using hydrothermal technology  

SciTech Connect

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. The most common process for the regeneration of GAC is the thermal method. Drawbacks associated with thermal regeneration include a 5--10% loss of carbon due to oxidation and attrition, a decrease in adsorption capacity, and high energy costs. The purpose of this study was to investigate the regeneration of GAC using hydrothermal technology. Phenol contaminated and non-contaminated GAC samples were regenerated using supercritical water (411 deg C and 26.2 MPa) with dissolved oxygen concentrations of 0 mg/L, 5 mg/L, and 100 mg/L. For comparative purposes, GAC was regenerated using subcritical water (300 deg C and 12.4 MPa) with a dissolved oxygen concentration of 5 mg/L. Regenerated GAC samples were evaluated in terms of adsorption capacity, BET surface area, pore volume, and average pore size. After four adsorption-regeneration cycles, using supercritical water (SCW) regeneration, the average adsorption capacity of regenerated GAC was found to be 90% of that of virgin GAC. Although a slightly higher adsorption capacity was achieved for regeneration with degassed water, the overall impact of dissolved oxygen was insignificant. The high adsorption capacity achieved for SCW was not observed for subcritical water regeneration. After four adsorption-regeneration cycles, only 67% of the original adsorption capacity was restored. The better results observed for SCW, as compared to subcritical water, were related to two factors. First, the higher regeneration temperatures of SCW resulted in increased thermal desorption. Second, the increased solubility of organic compounds and enhanced mass transfer rates in SCW resulted in a more efficient extraction process.

Sufnarski, M.D.

1999-05-01

301

Helical graphitic carbon nitrides with photocatalytic and optical activities.  

PubMed

Graphitic carbon nitride can be imprinted with a twisted hexagonal rod-like morphology by a nanocasting technique using chiral silicon dioxides as templates. The helical nanoarchitectures promote charge separation and mass transfer of carbon nitride semiconductors, enabling it to act as a more efficient photocatalyst for water splitting and CO2 reduction than the pristine carbon nitride polymer. This is to our knowledge a unique example of chiral graphitic carbon nitride that features both left- and right-handed helical nanostructures and exhibits unique optical activity to circularly polarized light at the semiconductor absorption edge as well as photoredox activity for solar-to-chemical conversion. Such helical nanostructured polymeric semiconductors are envisaged to hold great promise for a range of applications that rely on such semiconductor properties as well as chirality for photocatalysis, asymmetric catalysis, chiral recognition, nanotechnology, and chemical sensing. PMID:25220601

Zheng, Yun; Lin, Lihua; Ye, Xiangju; Guo, Fangsong; Wang, Xinchen

2014-10-27

302

Precursor materials suitability for super activated carbons production  

Microsoft Academic Search

Low cost-high availability materials (pet coke, charcoals, lignite and used tire char), not extensively investigated in the past, were chemically activated with KOH. Produced activated carbons demonstrated high adsorption capacities both in the gas and liquid phase as exemplified by N2 and methylene blue adsorption experiments and the application of BET and Langmuir equations and the DR method. An exception

G. G. Stavropoulos

2005-01-01

303

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

SciTech Connect

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

Ku, B.J.; Rhee, H.K. (Seoul National Univ. (Korea, Republic of). Dept. of Chemical Engineering); Lee, J.K.; Park, D. (Korea Inst. of Science and Technology, Seoul (Korea, Republic of))

1994-11-01

304

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

Microsoft Academic Search

Activated carbon has been prepared from molasses, a natural precursor of vegetable origin resulting from the sugar industry in Morocco. The preparation of the activated carbon from the molasses has been carried out by impregnation of the precursor with sulphuric acid, followed by carbonisation at varying conditions (temperature and gas coverage) in order to optimize preparation parameters. The influence of

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

2005-01-01

305

Factors influencing the rate of gold cyanide leaching and adsorption on activated carbon, and their impact on the design of CIL and CIP circuits  

Microsoft Academic Search

The carbon in pulp (CIP) and carbon in leach (CIL) processes became firmly established in the gold mining industry in the 1980s, initially in South Africa and Australia, from where they spread rapidly to all the gold producing regions of the world. The percentage of annual global gold production by activated carbon-based processes grew from zero in the 1970s to

C. A. Fleming; A. Mezei; E. Bourricaudy; M. Canizares; M. Ashbury

2011-01-01

306

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

307

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...

308

Microbial activity promotes carbon storage in temperate soils  

NASA Astrophysics Data System (ADS)

Soils are one of the most important carbon sink and sources. Soils contain up to 3/4 of all terrestrial carbon. Beside physical aspects of soil properties (e.g. soil moisture and texture) plants play an important role in carbon sequestration. The positive effect of plant diversity on carbon storage is already known, though the underlying mechanisms remain still unclear. In the frame of the Jena Experiment, a long term biodiversity experiment, we are able to identify these processes. Nine years after an land use change from an arable field to managed grassland the mean soil carbon concentrations increased towards the concentrations of permanent meadows. The increase was positively linked to a plant diversity gradient. High diverse plant communities produce more biomass, which in turn results in higher amounts of litter inputs. The plant litter is transferred to the soil organic matter by the soil microbial community. However, higher plant diversity also causes changes in micro-climatic condition. For instance, more diverse plant communities have a more dense vegetation structure, which reduced the evaporation of soils surface and thus, increases soil moisture in the top layer. Higher inputs and higher soil moisture lead to an enlarged respiration of the soil microbial community. Most interestingly, the carbon storage in the Jena Experiment was much more related to microbial respiration than to plant root inputs. Moreover, using radiocarbon, we found a significant younger carbon age in soils of more diverse plant communities than in soils of lower diversity, indicating that more fresh carbon is integrated into the carbon pool. Putting these findings together, we could show, that the positive link between plant diversity and carbon storage is due to a higher microbial decomposition of plant litter, pointing out that carbon storage in soils is a function of the microbial community.

Lange, Markus; Eisenhauer, Nico; Sierra, Carlos; Gleixner, Gerd

2014-05-01

309

CHARACTERIZATION OF ACTIVATED CARBONS PREPARED FROM SUGARCANE BAGASSE BY ZnCl2 ACTIVATION  

Microsoft Academic Search

Activated carbons were prepared from the agricultural waste of sugarcane bagasse by the chemical activation with zinc chloride (ZnCl2) at the activation temperature of 500°C with soaking time of 0.5 hour. The influence of activation parameters on the final carbon products was examined by varying the impregnation ratio (i.e., mass ratio of added ZnCl2 to bagasse) and bagasse size. The

W. T. Tsai; C. Y. Chang; M. C. Lin; S. F. Chien; H. F. Sun; M. F. Hsieh

2001-01-01

310

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. PMID:23983522

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

2009-01-01

311

Optimizing a Laser Process for Making Carbon Nanotubes  

NASA Technical Reports Server (NTRS)

A systematic experimental study has been performed to determine the effects of each of the operating conditions in a double-pulse laser ablation process that is used to produce single-wall carbon nanotubes (SWCNTs). The comprehensive data compiled in this study have been analyzed to recommend conditions for optimizing the process and scaling up the process for mass production. The double-pulse laser ablation process for making SWCNTs was developed by Rice University researchers. Of all currently known nanotube-synthesizing processes (arc and chemical vapor deposition), this process yields the greatest proportion of SWCNTs in the product material. The aforementioned process conditions are important for optimizing the production of SWCNTs and scaling up production. Reports of previous research (mostly at Rice University) toward optimization of process conditions mention effects of oven temperature and briefly mention effects of flow conditions, but no systematic, comprehensive study of the effects of process conditions was done prior to the study described here. This was a parametric study, in which several production runs were carried out, changing one operating condition for each run. The study involved variation of a total of nine parameters: the sequence of the laser pulses, pulse-separation time, laser pulse energy density, buffer gas (helium or nitrogen instead of argon), oven temperature, pressure, flow speed, inner diameter of the flow tube, and flow-tube material.

Arepalli, Sivaram; Nikolaev, Pavel; Holmes, William

2010-01-01

312

Improved granular activated carbon for the stabilization of wastewater pH  

SciTech Connect

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

NONE

1996-10-01

313

Thermodynamics of adsorption of acetone on active carbon supported metal adsorbents  

Microsoft Academic Search

Adsorption of acetone on active carbon and active carbon supported metals (Ni, Cu, Zn and Cd) have been studied as a function of temperature. Thermodynamic parameters such as ?G0, ?H0, and ?S0 are calculated from virial and Langmuir isotherm expressions. It is observed that active carbon supported metals have more adsorption affinity for acetone as compared to active carbon. Results

M. Afzal; F. Mahmood; M. Saleem

1992-01-01

314

Gasification characteristics of an activated carbon catalyst during the decomposition of hazardous waste material in supercritical water  

SciTech Connect

Recently, carbonaceous materials including activated carbon were proven to be effective catalysts for hazardous waste gasification in supercritical water. Using coconut shell activated carbon catalyst, complete decomposition of industrial organic wastes including methanol and acetic acid was achieved. During this process, the total mass of the activated carbon catalyst changes by two competing processes: a decrease in weight via gasification of the carbon by supercritical water, or an increase in weight by deposition of carbonaceous materials generated by incomplete gasification of the biomass feedstocks. The deposition of carbonaceous materials does not occur when complete gasification is realized. Gasification of the activated carbon in supercritical water is often favored, resulting in changes in the quality and quantity of the catalyst. To thoroughly understand the hazardous waste decomposition process, a more complete understanding of the behavior of activated carbon in pure supercritical water is needed. The gasification rate of carbon by water vapor at subcritical pressures was studied in relation to coal gasification and generating activated carbon.

Matsumura, Yukihiko; Nuessle, F.W.; Antal, M.J. Jr. [Univ. of Hawaii at Manoa, Honolulu, HI (United States)

1996-12-31

315

Binder-free activated carbon\\/carbon nanotube paper electrodes for use in supercapacitors  

Microsoft Academic Search

Novel inexpensive, light, flexible, and even rollup or wearable devices are required for multi-functional portable electronics and developing new versatile and flexible electrode materials as alternatives to the materials used in contemporary batteries and supercapacitors is a key challenge. Here, binder-free activated carbon (AC)\\/carbon nanotube (CNT) paper electrodes for use in advanced supercapacitors have been fabricated based on low-cost, industrial-grade

Guanghui Xu; Chao Zheng; Qiang Zhang; Jiaqi Huang; Mengqiang Zhao; Jingqi Nie; Xianghua Wang; Fei Wei

2011-01-01

316

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

317

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)] [Nanyang Technological Univ., Singapore (Singapore)

1999-01-01

318

The environmental applications of activated carbon/zeolite composite materials.  

PubMed

Over the past couple of years, the resurgence of placing an effective and sustainable amendment to combat against the auxiliary industrial entities, remains a highly contested agenda from a global point. With the renaissance of activated carbon, there has been a steadily growing interest in the research field. Recently, the adoption of zeolite composite, a prestigious advanced catalyst which formulates the enhancement of adsorption rate and hydrogen storage capability, has fore fronted to be a new growing branch in the scientific community. Confirming the assertion, this paper presents a state of art review of activated carbon/zeolite composite technology, its fundamental background studies, and environmental implications. Moreover, its major challenges together with the future expectation are summarized and discussed. Conclusively, the expanding of activated carbon/zeolite composite represents a potentially viable and powerful tool, leading to the plausible improvement of environmental preservation. PMID:21035101

Foo, K Y; Hameed, B H

2011-02-17

319

Recent advances in palladium-catalyzed carbon-carbon and carbon-boron bond forming processes  

E-print Network

Chapter 1. Highly active and efficient catalyst systems derived from palladium precatalysts and monophosphine ligands for the Suzuki-Miyaura cross-coupling reaction of heteroaryl boronic acids and esters has been developed. ...

Billingsley, Kelvin L

2008-01-01

320

Energy of activation for the decomposition of the alkaline-earth carbonates from thermogravimetric data  

Microsoft Academic Search

Activation energies for the vacuum thermal decomposition of calcium, strontium and barium carbonates have been determined from thermogravimetric data, using the Coats and Redfern equation. A computer program, written in 4100 Algol, was used to process the data and to obtain the order (n) of the decomposition reactions. In all three cases, a value ofn=2\\/3 was in closest agreement with

M. D. Judd; M. I. Pope

1972-01-01

321

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

Microsoft Academic Search

Capturing of odorous compounds such as toluene vapor by a particulate activated carbon adsorbent was investigated in a gas-solid cyclone, which is one of mobile beds. The test cyclone was early modified with the PoC and a spiral flow guide to the vortex finder. The proposed process may contribute to the reduction of gases and dust from industrial exhausts, especially

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

2012-01-01

322

OPTIMIZATION STUDY OF A PILOT ROTARY KILN FOR ACTIVATED CARBON PRODUCTION  

Microsoft Academic Search

This work presents an optimization study of the steady operation of a pilot rotary kiln, used to manufacture activated carbon (AC) from eucalyptus wood. The main goal proposed is the maximization of a process operating profit, which has been achieved maintaining a good quality product and maximum production yield. The objective function represents the operating profit and includes incomes by

Oscar A. Ortiz; Nora D. Martínez; A. Mengual; Pablo M. Aballay

323

Modeling of mercury desorption from activated carbon at elevated temperatures under fluidized\\/fixed bed operations  

Microsoft Academic Search

An effective method for controlling elemental mercury emission is to employ activated carbon (AC) to adsorb mercury from the combustion flue gas. An environmental concern regarding the process is the low sorption capacity of AC. The mercury control practice, therefore, will need a large quantity of fresh AC and generate an equally large quantity of spent AC contaminated with various

T. C. Ho; Y. Lee; H. W. Chu; C. J. Lin; J. R. Hopper

2005-01-01

324

Effects of Biodegradation and Background Inorganic Substances on Granular Activated Carbon Adsorption of Wastewater  

Microsoft Academic Search

Background inorganic substances are thought to disrupt the adsorption process used in wastewater treatment systems. In this study, a low-strength synthetic wastewater was investigated for biodegradation and adsorption onto granular activated carbon, with and without the presence of background inorganic compounds. Overall, organic compounds in the synthetic wastewater underwent slow biodegradation, but when a solution was prepared with only one

D. S. Chaudhary; S. Vigneswaran; H. H. Ngo; S. H. Kim; H. Moon

2003-01-01

325

EFFECTIVENESS OF ACTIVATED CARBON FOR REMOVAL OF TOXIC AND/OR CARCINOGENIC COMPOUNDS FROM WATER SUPPLIES  

EPA Science Inventory

This research addressed quantification of the performance of fixed-bed granular activated carbon processes for treatment of public water supplies. It included evaluation of the adsorption of selected toxic and/or carcinogenic trace compounds of man-related origin, including carbo...

326

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...

327

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

PubMed

The specific adsorption of oxygenated and aliphatic gasoline components onto activated carbons (ACs) was studied under static and dynamic conditions. Ethanol and n-octane were selected as target molecules. A highly porous activated carbon (CA) was prepared by means of two processes: carbonization and chemical activation of olive stone residues. Different types of oxygenated groups, identified and quantified by TPD and XPS, were generated on the CA surface using an oxidation treatment with ammonium peroxydisulfate and then selectively removed by thermal treatments, as confirmed by TPD results. Chemical and porous transformations were carefully analyzed throughout these processes and related to their VOC removal performance. The analysis of the adsorption process under static conditions and the thermal desorption of VOCs enabled us to determine the total adsorption capacity and regeneration possibilities. Breakthrough curves obtained for the adsorption process carried out under dynamic conditions provided information about the mass transfer zone in each adsorption bed. While n-octane adsorption is mainly determined by the porosity of activated carbons, ethanol adsorption is related to their surface chemistry, and in particular is enhanced by the presence of carboxylic acid groups. PMID:24239258

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

2013-12-15

328

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

329

Adsorption characteristics of selected hydrophilic and hydrophobic micropollutants in water using activated carbon.  

PubMed

In this study, we investigated adsorption characteristics of nine selected micropollutants (six pharmaceuticals, two pesticides, and one endocrine disruptor) in water using an activated carbon. The effects of carbon dosage, contact time, pH, DOM (dissolved organic matter), and temperature on the adsorption removal of micropollutants were examined. Increasing carbon dosage and contact time enhanced the removal of micropollutants. Sorption coefficients of hydrophilic compounds (caffeine, acetaminophen, sulfamethoxazole, and sulfamethazine) fit a linear isotherm and hydrophobic compounds (naproxen, diclofenac, 2, 4-D, triclocarban, and atrazine) fit a Freundlich isotherm. The removal of hydrophobic pollutants and caffeine were independent of pH changes, but acetaminophen, sulfamethazine, and sulfamethoxazole were adsorbed by mainly electrostatic interaction with activated carbon and so were affected by pH. The decrease in adsorption removal in surface water samples was observed and this decrease was more significant for hydrophobic than hydrophilic compounds. The decline in the adsorption capacity in surface water samples is caused by the competitive inhibition of DOM with micropollutants onto activated carbon. Low temperature (5°C) also decreased the adsorption removal of micropollutants, and affected hydrophobic compounds more than hydrophilic compounds. The results obtained in this study can be applied to optimize the adsorption capacities of micropollutants using activated carbon in water treatment process. PMID:24572271

Nam, Seung-Woo; Choi, Dae-Jin; Kim, Seung-Kyu; Her, Namguk; Zoh, Kyung-Duk

2014-04-15

330

Gas permeation carbon capture --- Process modeling and optimization  

SciTech Connect

A multi-staged gas permeation carbon capture process model was developed in Aspen Custom Modeler{reg_sign} (ACM) and optimized in the context of the retrofit of a 550 MW subcritical pulverized coal (PC) power plant. The gas permeation stages in the process are described by a custom multi-component, hollowfiber membrane model. Gas transport across the asymmetric membrane was modeled according to the solution-diffusion model for the selective skin layer and the assumption of negligible flux resistance by the porous support. Counter-current, one-dimensional plug flow was assumed with permeate pressure drop in the fiber lumen side due to capillary constrained flow. A modular optimization framework was used to minimize the levelized cost of electricity (LCOE) by optimizing a set of key process variables. The framework allows the external control of multiple simulation modules from different software packages from a common interface.

Morinelly, Juan; Miller, David

2011-01-01

331

Dry-processable carbon nanotubes for functional devices and composites.  

PubMed

Assembly of carbon nanotubes (CNTs) in effective and productive ways is of vital importance to their application. Recent progress in synthesis of CNTs has inspired new strategies for utilizing the unique physiochemical properties of CNTs in macroscale materials and devices. Assembling CNTs by dry processes (e.g., directly collecting CNTs in the form of freestanding films followed by pressing, stretching, and multilayer stacking instead of dispersing them in solution) not only considerably simplifies the processes but also avoids structural damage to the CNTs. Various dry-processable CNTs are reviewed, focusing on their synthesis, properties, and applications. The synthesis techniques are organized in terms of aggregative morphologies and microstructure control of CNTs. Important applications such as functional thin-film devices, strong CNT films, and composites are included. The opportunities and challenges in the synthesis techniques and fabrication of advanced composites and devices are discussed. PMID:25123967

Di, Jiangtao; Wang, Xin; Xing, Yajuan; Zhang, Yongyi; Zhang, Xiaohua; Lu, Weibang; Li, Qingwen; Zhu, Yuntian T

2014-11-01

332

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

333

Adsorption of uranium from aqueous solutions using activated carbon  

SciTech Connect

The adsorption of uranium from aqueous solution has been investigated using conventional commercially available activated carbons. It was found that treatment with hot nitric acid oxidized the surface of activated carbon and significantly increased the adsorption capacity for uranium in near-neutral and slightly acidic nitrate solutions. Equilibrium data were fitted to a simplified Freundlich isotherm for the purpose of comparison of oxidized and as-received samples. The decontamination of aqueous solutions was investigated in small column experiments. An ion-exchange mechanism of uranium sorption from aqueous solution is discussed. 43 refs., 11 figs., 1 tab.

Abbasi, W.A. (Pakistan Atomic Energy Commission, Islamabad (Pakistan)); Streat, M. (Loughborough Univ. of Technology, Leicestershire (United Kingdom))

1994-06-01

334

Removal of benzocaine from water by filtration with activated carbon  

USGS Publications Warehouse

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

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

1990-01-01

335

Improved granular activated carbon for the stabilization of wastewater PH  

SciTech Connect

Laboratory studies have identified the cause of the pH rise, which occurs during water treatment with activated carbon, as an interaction between the naturally occurring anions and protons in the water and the carbon surface. The interaction can be described as an ion exchange type of phenomenon, in which the carbon surface sorbs the anions and corresponding hydronium ions from the water. These studies have shown that the anion sorption and resulting pH increase is independent of the raw material used for the activated carbon production, e.g. bituminous or subbituminous coal, peat, wood or coconut. Also, the pH excursions occur with virgin, reactivated, and acid washed granular carbons. Current pH control technologies focus on adjustment of the wastewater pH prior to discharge or recycle of the initial effluent water until the pH increase abates. However, improved water pH control options have been realized by altering the carbon surface through controlled oxidation rather than the water chemistry or extended preprocessing at the treatment site.

Farmer, R.W.; Dussert, B.W.; Kovacic, S.L. [Calgon Carbon Corp., Pittsburgh, PA (United States)

1996-12-31

336

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

337

Laser Processing of Carbon Nanotube Transparent Conducting Films  

NASA Astrophysics Data System (ADS)

Transparent conducting films, or TCFs, are 2D electrical conductors with the ability to transmit light. Because of this, they are used in many popular electronics including smart phones, tablets, solar panels, and televisions. The most common material used as a TCF is indium tin oxide, or ITO. Although ITO has great electrical and optical characteristics, it is expensive, brittle, and difficult to pattern. These limitations have led researchers toward other materials for the next generation of displays and touch panels. The most promising material for next generation TCFs is carbon nanotubes, or CNTs. CNTs are cylindrical tubes of carbon no more than a few atoms thick. They have different electrical and optical properties depending on their atomic structure, and are extremely strong. As an electrode, they conduct electricity through an array of randomly dispersed tubes. The array is highly transparent because of gaps between the tubes, and size and optical properties of the CNTs. Many research groups have tried making CNT TCFs with opto-electric properties similar to ITO but have difficultly achieving high conductivity. This is partly attributed to impurities from fabrication and a mix of different tube types, but is mainly caused by low junction conductivity. In functionalized nanotubes, junction conductivity is impaired by covalently bonded molecules added to the sidewalls of the tubes. The addition of this molecule, known as functionalization, is designed to facilitate CNT dispersion in a solvent by adding properties of the molecule to the CNTs. While necessary for a good solution, functionalization decreases the conductivity in the CNT array by creating defects in the tube's structures and preventing direct inter-carbon bonding. This research investigates removing the functional coating (after tube deposition) by laser processing. Laser light is able to preferentially heat the CNTs because of their optical and electrical properties. Through local conduction, the relatively weak functional molecules are thermally decomposed. This restores the pristine CNT structure and allows carbon to carbon bonds to form; thereby significantly improving the junction and sheet conductivity. Laser processing is performed without damaging the TCF substrate (usually glass or PET) because laser light is not absorbed by the substrate and conduction from the CNTs is limited. In addition to removing the functional coating, laser light improves the electrical conductivity by purifying the CNT array. The purity is improved through the ablation of defective tubes and amorphous carbon in the CNT film.[1] Using higher laser power, it is possible to locally remove the CNTs. Selective laser removal of the CNTs is a dry process that can be used to pattern the electrode. This is a much simpler and less expensive patterning technique than wet acid etching used for ITO. In summary, laser processing of CNT TCFs is shown to improve the electrical conductivity by defunctionalizing the CNTs. In addition, laser exposure increases purity by removing defects and can be used to pattern the electrode. These advances make CNTs more competitive as an alternative for ITO which has both cost and performance limitations. [1] T. Ueda, S. K. (2008). Effect of laser irradiation on carbon nanotube films for NOx gas sensor. Surface & Coatings Technology, 202, 5325--5328.

Mann, Andrew

338

Optimizing biofilter performance with activated carbon  

Microsoft Academic Search

Fisher Controls developed a formal plan to eliminate its toxic air emissions. Its first goal was to reduce 90 percent of its hazardous air pollutants by the end of 1993 through various process changes. This target is followed by another, more stringent goal, of a 99 percent reduction by 1999. The remaining 10 percent of emissions are from dozens of

D. Blackerby; K. Nelson

1994-01-01

339

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

340

Tc-99 Adsorption on Selected Activated Carbons - Batch Testing Results  

SciTech Connect

CH2M HILL Plateau Remediation Company (CHPRC) is currently developing a 200-West Area groundwater pump-and-treat system as the remedial action selected under the Comprehensive Environmental Response, Compensation, and Liability Act Record of Decision for Operable Unit (OU) 200-ZP-1. This report documents the results of treatability tests Pacific Northwest National Laboratory researchers conducted to quantify the ability of selected activated carbon products (or carbons) to adsorb technetium-99 (Tc-99) from 200-West Area groundwater. The Tc-99 adsorption performance of seven activated carbons (J177601 Calgon Fitrasorb 400, J177606 Siemens AC1230AWC, J177609 Carbon Resources CR-1240-AW, J177611 General Carbon GC20X50, J177612 Norit GAC830, J177613 Norit GAC830, and J177617 Nucon LW1230) were evaluated using water from well 299-W19-36. Four of the best performing carbons (J177606 Siemens AC1230AWC, J177609 Carbon Resources CR-1240-AW, J177611 General Carbon GC20X50, and J177613 Norit GAC830) were selected for batch isotherm testing. The batch isotherm tests on four of the selected carbons indicated that under lower nitrate concentration conditions (382 mg/L), Kd values ranged from 6,000 to 20,000 mL/g. In comparison. Under higher nitrate (750 mg/L) conditions, there was a measureable decrease in Tc-99 adsorption with Kd values ranging from 3,000 to 7,000 mL/g. The adsorption data fit both the Langmuir and the Freundlich equations. Supplemental tests were conducted using the two carbons that demonstrated the highest adsorption capacity to resolve the issue of the best fit isotherm. These tests indicated that Langmuir isotherms provided the best fit for Tc-99 adsorption under low nitrate concentration conditions. At the design basis concentration of Tc 0.865 µg/L(14,700 pCi/L), the predicted Kd values from using Langmuir isotherm constants were 5,980 mL/g and 6,870 mL/g for for the two carbons. These Kd values did not meet the target Kd value of 9,000 mL/g. Tests conducted to ascertain the effects of changing pH showed that at pH values of 6.5 and 7.5, no significant differences existed in Tc-adsorption performance for three of the carbons, but the fourth carbon performed better at pH 7.5. When the pH was increased to 8.5, a slight decline in performance was observed for all carbons. Tests conducted to ascertain the temperature effect on Tc-99 adsorption indicated that at 21 ºC, 27 ºC, and 32 ºC there were no significant differences in Tc-99 adsorption for three of the carbons. The fourth carbon showed a noticeable decline in Tc-99 adsorption performance with increasing temperature. The presence of volatile organic compounds (VOCs) in the source water did not significantly affect Tc-99 adsorption on either of two carbons tested. Technetium-99 adsorption differed by less than 15% with or without VOCs present in the test water, indicating that Tc-99 adsorption would not be significantly affected if VOCs were removed from the water prior to contact with carbon.

Mattigod, Shas V.; Wellman, Dawn M.; Golovich, Elizabeth C.; Cordova, Elsa A.; Smith, Ronald M.

2010-12-01

341

Adsorption studies of methylene blue and phenol onto vetiver roots activated carbon prepared by chemical activation  

Microsoft Academic Search

Vetiver roots have been utilized for the preparation of activated carbon (AC) by chemical activation with different impregnation ratios of phosphoric acid, XP (gH3PO4\\/g precursor): 0.5:1; 1:1 and 1.5:1. Textural characterization, determined by nitrogen adsorption at 77K shows that mixed microporous and mesoporous structures activated carbons (ACs) with high surface area (>1000m2\\/g) and high pore volume (up to 1.19cm3\\/g) can

Sandro Altenor; Betty Carene; Evens Emmanuel; Jacques Lambert; Jean-Jacques Ehrhardt; Sarra Gaspard

2009-01-01

342

Material processing with hydrogen and carbon monoxide on Mars  

NASA Technical Reports Server (NTRS)

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. Hydrogen can be reacted with CO to produce a wide variety of hydrocarbons, alcohols, and other organic compounds. Methanol, produced by Fischer-Tropsch chemistry may be useful as a fuel; it is easy to store and handle because it is a liquid at Mars temperatures. The reduction of CO2 to hydrocarbons such as methane or acetylene can be accomplished with hydrocarbons. Carbon monoxide and hydrogen require cryogenic temperatures for storage as liquid. Noncryogenic storage of hydrogen may be accomplished using hydrocarbons, inorganic hydrides, or metal hydrides. Noncryogenic storage of CO may be accomplished in the form of iron carbonyl (FE(CO)5) or other metal carbonyls. Low hydrogen content fuels such as acetylene (C2H2) may be effective propellants with low requirements for earth derived resources. The impact on manned Mars missions of alternative propellant production and utilization is discussed.

Hepp, Aloysius F.; Linne, Diane L.; Landis, Geoffrey A.

1991-01-01

343

Automatic Control of Arc Process for Making Carbon Nanotubes  

NASA Technical Reports Server (NTRS)

An automatic-control system has been devised for a process in which carbon nanotubes are produced in an arc between a catalyst-filled carbon anode and a graphite cathode. The control system includes a motor-driven screw that adjusts the distance between the electrodes. The system also includes a bridge circuit that puts out a voltage proportional to the difference between (1) the actual value of potential drop across the arc and (2) a reference value between 38 and 40 V (corresponding to a current of about 100 A) at which the yield of carbon nanotubes is maximized. Utilizing the fact that the potential drop across the arc increases with the interelectrode gap, the output of the bridge circuit is fed to a motor-control circuit that causes the motor to move the anode toward or away from the cathode if the actual potential drop is more or less, respectively, than the reference potential. Thus, the system regulates the interelectrode gap to maintain the optimum potential drop. The system also includes circuitry that records the potential drop across the arc and the relative position of the anode holder as function of time.

Scott, Carl D.; Pulumbarit, Robert B.; Victor, Joe

2004-01-01

344

Material processing with hydrogen and carbon monoxide on Mars  

NASA Technical Reports Server (NTRS)

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. Hydrogen can be reacted with CO to produce a wide variety of hydrocarbons, alcohols, and other organic compounds. Methanol, produced by Fischer-Tropsch chemistry may be useful as a fuel; it is easy to store and handle because it is a liquid at Mars temperatures. The reduction of CO2 to hydrocarbons such as methane or acetylene can be accomplished with hydrogen. Carbon monoxide and hydrogen require cryogenic temperatures for storage as liquids. Noncryogenic storage of hydrogen may be accomplished using hydrocarbons, inorganic hydrides, or metal hydrides. Noncryogenic storage of CO may be accomplished in the form of iron carbonyl (FE(CO)5) or other metal carbonyls. Low hydrogen content fuels such as acetylene (C2H2) may be effective propellants with low requirements for earth derived resources. The impact on manned Mars missions of alternative propellant production and utilization is discussed.

Hepp, Aloysius F.; Landis, Geoffrey A.; Linne, Diane L.

1991-01-01

345

Mechanisms of Carbon Nanotube Production by Laser Ablation Process  

NASA Technical Reports Server (NTRS)

We will present possible mechanisms for nanotube production by laser oven process. Spectral emission of excited species during laser ablation of a composite graphite target is compared with that of laser irradiated C60 vapor. The similarities in the transient and spectral data suggest that fullerenes are intermediate precursors for nanotube formation. The confinement of the ablation products by means of a 25-mm diameter tube placed upstream of the target seems to improve the production and purity of nanotubes. Repeated laser pulses vaporize the amorphous/graphitic carbon and possibly catalyst particles, and dissociate fullerenes yielding additional feedstock for SWNT growth.

Scott, Carl D.; Arepalli, Sivaram; Nikolaev, Pavel; Smalley, Richard E.; Nocholson, Leonard S. (Technical Monitor)

2000-01-01

346

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

347

Adsorption of cadmium ions on oxygen surface sites in activated carbon  

SciTech Connect

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

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

2000-02-08

348

The removal of organic pollutants by ultrafiltration and adsorption onto fibrous activated carbon  

SciTech Connect

The adsorption of micropollutants in aqueous solutions showed a high adsorption velocity of fiber activated carbon (FAC) compared to granular activated carbon (GAC), and was similar to that of powder activated carbon (PAC). A selectivity of FAC was also found. From these results an ultrafiltration (LTF) membrane is coupled with FAC to remove successively macromolecules (humic substances) and phenols present together in an aqueous solution. This new and original approach to a water treatment compact process is successfully put to use. The influence of operating parameters such as water velocities, between 0.6 and 2.07 m. h{sup -1} and FAC thickness in the range 4 to 16 mm is investigated. Industrial developments are put forward.

Le Cloirec, P.; Brasquet, C. [UMR Subatech, Ecole des Mines de Nantes (France); Subrenat, E. [Actitex, Levallois (France)

1996-10-01

349

Increased oxidation-related glutathionylation and carbonic anhydrase activity in endometriosis.  

PubMed

This study examined the possible involvement of carbonic anhydrase activation in response to an endometriosis-related increase in oxidative stress. Peripheral blood samples obtained from 27 healthy controls and 30 endometriosis patients, classified as having endometriosis by histological examination of surgical specimens, were analysed by multiple immunoassay and carbonic anhydrase activity assay. Red blood cells (RBC) were analysed for glutathionylated protein (GSSP) content in the membrane, total glutathione (GSH) in the cytosol and carbonic anhydrase concentration and activity. In association with a membrane increase of GSSP and a cytosolic decrease of GSH content in endometriosis patients, carbonic anhydrase significantly increased (P < 0.0001) both monomerization and activity compared with controls. This oxidation-induced activation of carbonic anhydrase was positively and significantly correlated with the GSH content of RBC (r = 0.9735, P < 0.001) and with the amount of the 30-kDa monomer of carbonic anhydrase (r = 0.9750, P < 0.001). Because carbonic anhydrase activation is implied in many physiological and biochemical processes linked to pathologies such as glaucoma, hypertension, obesity and infections, carbonic anhydrase activity should be closely monitored in endometriosis. These data open promising working perspectives for diagnosis and treatment of endometriosis and hopefully of other oxidative stress-related diseases. Endometriosis is a chronic disease associated with infertility and local inflammatory response, which is thought to spread rapidly throughout the body as a systemic subclinical inflammation. One of the causes in the pathogenesis/evolution of endometriosis is oxidative stress, which occurs when reactive oxygen species are produced faster than the endogenous antioxidant defence systems can neutralize them. Once produced, reactive oxygen species can alter the morphological and functional properties of endothelial cells, including permeability and adhesion molecule expression, thus contributing to ongoing inflammation. Due to their main cellular functions--delivery of O2 from lung to tissue and removal of CO2 from tissue to lung--red blood cells (RBC) are exposed to oxidative stress. Carbon dioxide in tissue capillaries diffuses into red cells, where it is rapidly hydrated by the action of cytosolic carbonic anhydrase. Analysis of the oxidation status of endometriotic RBC membranes showed a high content of glutathionylated proteins, indicating pre-existing oxidation-related alterations. The increase in glutathionylated proteins was correlated to increased carbonic anhydrase activity in endometriotic RBC compared with healthy controls. Carbonic anhydrase is a family of metalloenzymes involved in many physiological processes such as acid-base homeostasis, respiration, carbon dioxide and ion transport, and bone resorption, and in the regulation of ureagenesis, gluconeogenesis, lipogenesis and tumourigenesis. Due to the potential implication of carbonic anhydrase activation in many pathologies, such as glaucoma, hypertension, obesity and infections, carbonic anhydrase activity should be closely monitored in endometriosis to prevent possible complications and/or worsening of related conditions. PMID:24746440

Andrisani, Alessandra; Donà, Gabriella; Brunati, Anna Maria; Clari, Giulio; Armanini, Decio; Ragazzi, Eugenio; Ambrosini, Guido; Bordin, Luciana

2014-06-01

350

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

PubMed

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 ( [Formula: see text] ), whereas the volume of meso-(V(2)) and macropores (V(3)) decreased slightly. Chemical characterization of the materials revealed that carbonization and especially activation process considerably increased the surface basicity of the sample. Original sample (A) presented acidic surface properties (pH(PZC)=4.5) with 21% surface oxygen, whereas the sample that underwent activation showed mainly basic surface chemical properties (pH(PZC)=9.5) with only 6% of surface oxygen. Carbonization and especially, activation process considerable increased the adsorption capacity of bromide and iodide ions. This would mainly be produced by (i) an increase in the microporosity of the sample, which increases Ag-adsorption sites available to halide anions, and (ii) a rise of the basicity of the sample, which produces an increase in attractive electrostatic interactions between the aerogel surface, positively charged at the working pH (pH(solution)carbonization and activation processes increased the adsorptive capacity of the aerogel sample. However, results showed that the adsorption capacity of the aerogel samples studied was considerably lower in water from Lake Zurich. Results showed X(0.02) (amount adsorbed to initial breakthrough) values of 0.1 and 4.3 mg/g for chloride anion and dissolved organic carbon (DOC), respectively, during bromide adsorption process in water from Lake Zurich. This indicates that the adsorptive capacity reduction observed may be due to (i) blocking of the porosity, caused by adsorption of dissolved organic matter on the aerogel surface, that would impede the access of bromide and iodide ions to Ag-adsorption sites, and (ii) the competition of chloride anions for the same adsorption sites. Bromide- and iodide-saturated columns were regenerated with NH(3) (0.02 M), observing little change in column characteristics. Moreover, the organic polymer precursors were not dissolved and the concentration of surface Ag-adsorption sites is not significantly changed after two adsorption/regeneration cycles. According to these results, Ag-doped activated carbon aerogels could be a very promising agents to remove bromide and iodide from drinking water. PMID:16696995

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

2006-08-01

351

Sulfurized activated carbon for high energy density supercapacitors  

NASA Astrophysics Data System (ADS)

Sulfurized activated carbon (SAC), made by coating the pore surface with thiophenic sulfur functional groups from the pyrolysis of sulfur flakes, were characterized and tested for supercapacitor applications. From X-ray photoelectron spectroscopy (XPS), the sulfur content in the SAC was found to be 2.7 at%. Electrochemical properties from potentiostatic and galvanostatic measurements, and electrochemical impedance spectroscopy (EIS) were used to evaluate the effect of sulfur on porous carbon electrodes. The SAC electrode exhibits better conductivity, and an obvious increase in specific capacitance that is almost 40% higher than plain activated carbons (ACs) electrode at a high current density of 1.4 A g-1. The proposed mechanism for improved conductivity and capacitive performance due to the sulfur functional groups on ACs will be discussed.

Huang, Yunxia; Candelaria, Stephanie L.; Li, Yanwei; Li, Zhimin; Tian, Jianjun; Zhang, Lili; Cao, Guozhong

2014-04-01

352

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

353

Steam or carbon dioxide-activated carbons from almond shells: physical, chemical and adsorptive properties and estimated cost of production  

Microsoft Academic Search

A series of steam- or carbon dioxide (CO2)-activated, granular activated carbons (GACs) were made from almond shells using six different activation or activation\\/oxidation conditions for each series. Unoxidized\\/oxidized pairs of GACs were compared among treatments and to two commercial GACs in order to determine the relative value of the carbons. Comparative terms included yield, surface area, attrition, surface charge, copper

Christopher A Toles; Wayne E Marshall; Lynda H Wartelle; Andrew McAloon

2000-01-01

354

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

355

Experimental investigation of factors controlling the calcium carbonate ion activity product of shallow water carbonate-rich sediments  

E-print Network

EXPERIMENTAL INVESTIGATION OF FACTORS CONTROLLING THE CALCIUM CARBONATE ION ACTIVITY PRODUCT OF SHALLOW WATER CARBONATE-RICH SEDIMENTS A Thesis by LAWRENCE DOUGLAS BERNSTEIN Submitted to the Graduate College of Texas A&M University... in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE December 1983 Major Subject: Oceanography EXPERIMENTAL INVESTIGATION OF FACTORS CONTROLLING THE CALCIUM CARBONATE ION ACTIVITY PRODUCT OF SHALLOW WATER CARBONATE...

Bernstein, Lawrence Douglas

2012-06-07

356

Saltwater intrusion into tidal freshwater marshes alters the biogeochemical processing of organic carbon  

NASA Astrophysics Data System (ADS)

Environmental perturbations in wetlands affect the integrated plant-microbial-soil system, causing biogeochemical responses that can manifest at local to global scales. The objective of this study was to determine how saltwater intrusion affects carbon mineralization and greenhouse gas production in coastal wetlands. Working with tidal freshwater marsh soils that had experienced roughly 3.5 yr of in situ saltwater additions, we quantified changes in soil properties, measured extracellular enzyme activity associated with organic matter breakdown, and determined potential rates of anaerobic carbon dioxide (CO2) and methane (CH4) production. Soils from the field plots treated with brackish water had lower carbon content and higher C : N ratios than soils from freshwater plots, indicating that saltwater intrusion reduced carbon availability and increased organic matter recalcitrance. This was reflected in reduced activities of enzymes associated with the hydrolysis of cellulose and the oxidation of lignin, leading to reduced rates of soil CO2 and CH4 production. The effects of long-term saltwater additions contrasted with the effects of short-term exposure to brackish water during three-day laboratory incubations, which increased rates of CO2 production but lowered rates of CH4 production. Collectively, our data suggest that the long-term effect of saltwater intrusion on soil CO2 production is indirect, mediated through the effects of elevated salinity on the quantity and quality of autochthonous organic matter inputs to the soil. In contrast, salinity, organic matter content, and enzyme activities directly influence CH4 production. Our analyses demonstrate that saltwater intrusion into tidal freshwater marshes affects the entire process of carbon mineralization, from the availability of organic carbon through its terminal metabolism to CO2 and/or CH4, and illustrate that long-term shifts in biogeochemical functioning are not necessarily consistent with short-term disturbance-type responses.

Neubauer, S. C.; Franklin, R. B.; Berrier, D. J.

2013-07-01

357

Saltwater intrusion into tidal freshwater marshes alters the biogeochemical processing of organic carbon  

NASA Astrophysics Data System (ADS)

Environmental perturbations in wetlands affect the integrated plant-microbial-soil system, causing biogeochemical responses that can manifest at local to global scales. The objective of this study was to determine how saltwater intrusion affects carbon mineralization and greenhouse gas production in coastal wetlands. Working with tidal freshwater marsh soils that had experienced ~ 3.5 yr of in situ saltwater additions, we quantified changes in soil properties, measured extracellular enzyme activity associated with organic matter breakdown, and determined potential rates of anaerobic carbon dioxide (CO2) and methane (CH4) production. Soils from the field plots treated with brackish water had lower carbon content and higher C : N ratios than soils from freshwater plots, indicating that saltwater intrusion reduced carbon availability and increased organic matter recalcitrance. This was reflected in reduced activities of enzymes associated with the hydrolysis of cellulose and the oxidation of lignin, leading to reduced rates of soil CO2 and CH4 production. The effects of long-term saltwater additions contrasted with the effects of short-term exposure to brackish water during three-day laboratory incubations, which increased rates of CO2 production but lowered rates of CH4 production. Collectively, our data suggest that the long-term effect of saltwater intrusion on soil CO2 production is indirect, mediated through the effects of elevated salinity on the quantity and quality of autochthonous organic matter inputs to the soil. In contrast, salinity, organic matter content, and enzyme activities directly influence CH4 production. Our analyses demonstrate that saltwater intrusion into tidal freshwater marshes affects the entire process of carbon mineralization, from the availability of organic carbon through its terminal metabolism to CO2 and/or CH4, and illustrate that long-term shifts in biogeochemical functioning are not necessarily consistent with short-term disturbance-type responses.

Neubauer, S. C.; Franklin, R. B.; Berrier, D. J.

2013-12-01

358

Kinetics of hydrocarbon adsorption on activated carbon and silica gel  

SciTech Connect

Experimental breakthrough results of methane, ethane and propane in activated carbon and silica gel obtained over a wide range of gas compositions, bed pressures, interstitial velocities, and column temperatures were analyzed using a dynamic, nonisothermal, nontrace column breakthrough model. A linear driving force (LDF) approximation is used for particle uptake, and the Langmuir-Freundlich isotherm represents adsorption equilibrium. The LDF mass-transfer-rate coefficient (and, hence, effective particle diffusivity) and column-wall heat-transfer coefficient were determined. The results show that hydrocarbon transport in the activated carbon particles used is essentially by Knudsen and surface flow, while for the silica gel used the transport is primarily by Knudsen flow. For activated carbon, the experimentally derived LDF coefficients for all three sorbates are well correlated using an average effective diffusivity value. With regard to heat transfer, the column-wall Nusselt number is approximately constant for the range of Reynolds numbers considered. Simulations of multicomponent breakthrough in the activated-carbon bed based on independently measured single-component kinetic parameters and the extended Langmuir-Freundlich isotherm agree very well with experimental results. The computational efficiency gained by adopting the simpler extended Langmuir isotherm model is also investigated.

Malek, A.; Farooq, S. [National Univ. of Singapore (Singapore). Dept. of Chemical Engineering] [National Univ. of Singapore (Singapore). Dept. of Chemical Engineering

1997-03-01

359

EVALUATION OF PROCEDURES TO DESORB BACTERIA FROM GRANULAR ACTIVATED CARBON  

EPA Science Inventory

Physical, chemical, and enzymatic means for the desorption of micro-organisms from granular activated carbon (GAC) were assessed. Data indicate that homogenization at 16,000 rpm for 3 min at 4 C with a mixture of peptone (0.01%), Zwittergent 3-12 ( times 10 to the minus 6 power M...

360

Activated carbon from vetiver roots: Gas and liquid adsorption studies  

Microsoft Academic Search

Large quantities of lignocellulosic residues result from the industrial production of essential oil from vetiver grass (Vetiveria zizanioides) roots. These residues could be used for the production of activated carbon. The yield of char obtained after vetiver roots pyrolysis follows an equation recently developed [A. Ouensanga, L. Largitte, M.A. Arsene, The dependence of char yield on the amounts of components

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

2007-01-01

361

Adsorption-induced Pore Expansion and Contraction in Activated Carbon  

NASA Astrophysics Data System (ADS)

Adsorbent materials such as activated carbon and Metal-Organic Frameworks (MOFs) have received significant attention as a potential storage material for hydrogen and natural gas.1 Typically the adsorbent material is assumed to consist of rigid slit- or cylindrical-shaped pores. Recent work has revealed the importance of the mechanical response of the adsorbent in the presence of an adsorbate. Here, we first demonstrate the flexibility of pore walls in activated carbon and the effect this has on the pore structure of the bulk samples. The interaction is modeled as a competition between Van der Waals interactions between neighboring walls and a resistance to bending due to the rigidity of graphene. Minimal energy configurations were calculated analytically for a simplified potential and numerically for a more realistic potential. The pore structures are discussed in the context of pore measurements on activated carbon samples. Following recent work by Cole and Neimark, large pressures due to an adsorbed film are predicted in the narrow pores of activated carbon. The coverage-dependent nature of adsorbed-film pressure, indicating a pressure-variant pore structure, is discussed in terms of adsorption isotherms.

Connolly, Matthew; Wexler, Carlos

2012-02-01

362

Granulated activated carbon water treatment and potential radiation hazards  

Microsoft Academic Search

Early enthusiasm for granular activated carbon (GAC) as the radon treatment medium of choice for very small systems has diminished in consideration of the secondary radiation problems it presents. GAC remains a viable treatment method for radon only at the low end of the radon concentration range. In domestic water supplies this is 5000 pCi\\/l or less. The initial cost

S. Rydell; B. Keene; J. Lowry

1989-01-01

363

Modification of the surface chemistry of activated carbons  

Microsoft Academic Search

A NORIT activated carbon was modified by different chemical and thermal treatments (including oxidation in the gas and liquid phases) in order to obtain materials with different surface properties. Several techniques were used to characterize these materials including nitrogen adsorption, chemical and thermal analyses, XPS, TPD and DRIFTS. The results obtained by TPD agree quantitatively with the elemental and proximate

J. L Figueiredo; M. F. R Pereira; M. M. A Freitas; J. J. M Órfão

1999-01-01

364

GAC (GRANULAR ACTIVATED CARBON) TREATMENT COSTS: A SENSITIVITY ANALYSIS  

EPA Science Inventory

Although admittedly effective for removing organic compounds, concerns have been raised about the cost of using GAC for treating drinking water. This paper is devoted to the discussion of the cost of granular activated carbon for removing organic compounds from drinking water. Ac...

365

Evaluation of the genetic activity of industrially produced carbon black  

SciTech Connect

Commercially produced oil furnace carbon black has been evaluated by five different assays for genetic activity. These were the Ames Salmonella typhimurium reverse mutation test, sister chromatid exchange test in CHO cells, mouse lymphoma test, cell transformation assay in C3H/10T 1/2 cells, and assay for genetic effects in Drosophila melanogaster. Limited cellular toxicity was exhibited but no significant genetic activity was noted.

Kirwin, C.J. (Phillips Petroleum Co., Bartlesville, OK); LeBlanc, J.V.; Thomas, W.C.; Haworth, S.R.; Kirby, P.E.; Thilagar, A.; Bowman, J.T.; Brusick, D.J.

1981-06-01

366

Intravascular Neutrophil Activation Due to Carbon Monoxide Poisoning  

Microsoft Academic Search

Rationale: We hypothesized that platelet-neutrophil interactions occur as a result of acute carbon monoxide (CO) poisoning, and subsequent neutrophil activation triggers events that cause neuro- logic sequelae. Objectives: To identify platelet-neutrophil interactions and neutro- phil activation in patients and in animal models, and to establish the association between these intravascular events and changes linked to CO-mediated neurologic sequelae in an

Stephen R. Thom; Veena M. Bhopale; Shih-Tsung Han; James M. Clark; Kevin R. Hardy

367

Characterisation and applications of activated carbon produced from Moringa oleifera seed husks by single-step steam pyrolysis  

Microsoft Academic Search

The seed husks of the multipurpose tree Moringa oleifera are potentially a waste product that may be available in large quantities, and previous work has demonstrated that a microporous activated carbon can be produced from them by carbonisation under nitrogen followed by activation in steam. This research examines the efficacy of a simpler and cheaper activation process, single-step steam pyrolysis

A. Michael Warhurst; Gordon L. McConnachie; Simon J. T. Pollard

1997-01-01

368

Bimodal activated carbons derived from resorcinol-formaldehyde cryogels  

NASA Astrophysics Data System (ADS)

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

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

2011-06-01

369

Influence of active sites organisation on calcium carbonate formation at model biomolecular interfaces  

E-print Network

Influence of active sites organisation on calcium carbonate formation at model biomolecular in the matrix. Formation of solid calcium carbonate with two- component monolayers on subphases containing.V. All rights reserved. Keywords: Mixed model monolayers; Calcium carbonate formation; Phospholipids

Hell, Stefan W.

370

77 FR 12614 - Activated Carbon From China; Institution of a Five-Year Review  

Federal Register 2010, 2011, 2012, 2013

...certain activated carbon, except California Carbon. The Commission found that appropriate circumstances existed to exclude California Carbon based on the related parties provision...supply and demand conditions or business cycle for the Domestic Like Product that...

2012-03-01

371

Investigation of Carbon Cycle Processes within a Managed Landscape: An Ecosystem Manipulation and Isotope Tracer Approach  

E-print Network

Investigation of Carbon Cycle Processes within a Managed Landscape: An Ecosystem Manipulation a better scientific understanding of carbon cycle processes within an agricultural landscape characteristic (AmeriFlux, Fluxnet, BASIN, etc), which aim to better understand global carbon cycling and climate change

Minnesota, University of

372

Removal of Heavy Metal Ions and Diethylenetriamine Species from Solutions by Magnetic Activated Carbon  

NASA Astrophysics Data System (ADS)

Even though activated carbon is widely used in the removal of contaminants from effluents, it is difficult to be completely recovered by screening or classification. In this project, we prepared a magnetic form of activated carbon (M-AC) by co-precipitation of iron oxides onto activated carbon surface. M-AC can be separated from solutions by applying an external magnetic field and regenerated for reuse. The synthesized M-AC was characterized by X-ray diffraction, specific surface area measurement, and scanning electron microscope. Characterization results show that the major phase of coated iron oxides is magnetite (Fe 3O4). Batch adsorption experiments were carried out for single-component and multi-component solutions. M-AC shows a better adsorption capacity for singlecomponent of Cu (II), Ni (II), or diethylenetriamine (DETA) and for multiple-components of Cu-DETA and Ni-DETA complexes in deionized water than activated carbon. M-AC also shows the potential application in carbon-in-pulp process for gold recovery.

Liu, Kaiwen

373

Electrocatalytic activity of nitrogen-doped carbon nanotube cups.  

PubMed

The electrochemical activity of stacked nitrogen-doped carbon nanotube cups (NCNCs) has been explored in comparison to commercial Pt-decorated carbon nanotubes. The nanocup catalyst has demonstrated comparable performance to that of Pt catalyst in oxygen reduction reaction. In addition to effectively catalyzing O(2) reduction, the NCNC electrodes have been used for H(2)O(2) oxidation and consequently for glucose detection when NCNCs were functionalized with glucose oxidase (GOx). Creating the catalysts entirely free of precious metals is of great importance for low-cost fuel cells and biosensors. PMID:19722487

Tang, Yifan; Allen, Brett L; Kauffman, Douglas R; Star, Alexander

2009-09-23

374

Enhanced mitigation of para-chlorophenol using stratified activated carbon adsorption columns.  

PubMed

The adsorptive removal of toxic para-chlorophenol using activated carbon adsorption columns is a proven effective engineering process. This paper examined the possibility to stratify an adsorbent bed into layers, in order to enhance the adsorption process performance in terms of increased column service time and adsorbent bed saturation. Four different types of fixed-bed adsorption columns are used and compared under the same operating conditions, but with the variation of column geometry and activated carbon particle size stratification. The Type 3 column - a cylindrical column with particle stratification packing, is found to be the most efficient choice, as the extent of column service time and adsorbent bed saturation are the largest. This could eventually decrease the frequency of adsorbent replacement/regeneration and hence reduce the operating cost of the fixed-bed adsorption process. The Homogeneous Surface Diffusion Model (HSDM) was applied successfully to describe the dynamic adsorption of para-chlorophenol onto Filtrasorb 400 (F400) activated carbon in different types of columns. The Redlich-Peterson isotherm model equation, an experimentally derived external mass transfer correlation and a constant surface diffusivity are used in the HSDM. The optimised surface diffusivity of para-chlorophenol is found to be 1.20E-8 cm(2)/s, which is in good agreement with other phenolics/F400 carbon diffusing systems in literature. PMID:22154109

Sze, Michael Fan Fu; McKay, Gordon

2012-03-01

375

Influences of pyrolysis condition and acid treatment on properties of durian peel-based activated carbon.  

PubMed

Durian peel was used for the synthesis of activated carbon used for adsorption of Basic Green 4 dye. Activated carbon was synthesised under either nitrogen (N(2)) atmospheric or vacuum pyrolysis, followed by carbon dioxide (CO(2)) activation. The synthesised activated carbon then was treated with hydrochloric acid (HCl) solution. The results showed that activated carbon synthesised under vacuum pyrolysis exhibited better properties and adsorption capacities than that under nitrogen atmospheric pyrolysis. The HCl treatment improved properties and adsorption capacities of activated carbons. Pseudo-second-order kinetics well described the adsorption of Basic Green 4. PMID:19695874

Nuithitikul, Kamchai; Srikhun, Sarawut; Hirunpraditkoon, Samorn

2010-01-01

376

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

PubMed

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

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

2013-01-01

377

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

PubMed Central

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

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

2013-01-01

378

Processing and applications of carbon based nano-materials  

NASA Astrophysics Data System (ADS)

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 new composites and devices. As-prepared SWNTs are typically contaminated with amorphous carbon as well as metal catalyst and graphitic nanoparticles. We have demonstrated an efficient approach for removing most of these impurities by the combination of nitric acid treatment and both low speed (2000 g) and high speed centrifugation (20,000 g). This approach gives rise to the highest-purified arc-discharge SWNTs which are almost free from impurities, and in addition are left in a low state of aggregation. The new purification process offers a convenient way to obtain different grade of SWNTs and allows the study of the effect purity on the thermal conductivity of SWNT epoxy composite. Purified functionalized SWNTs provide a significantly greater enhancement of the thermal conductivity, whereas AP-SWNTs allow the best electrical properties because of their ability to form efficient percolating network. We found that purified SWNTs provide ˜5 times greater enhancement of the thermal conductivity than the impure SWNT fraction demonstrating the significance of SWNTs quality for thermal management. The introduced GNPs have directed the thermal management project to a new avenue due to the significant improvement of the thermal conductivity of the composites in comparison with that of SWNTs. A novel process was demonstrated to achieve a 4-graphene layer structure referred to GNPs with a thickness of ˜2 nm. This material was embedded in an epoxy resin matrix and the measured thermal conductivity of the composite is up to 10 W/m·K with 40 vol% loading, which surpasses the performance of conventional fillers that require a loading of ˜70 vol% to achieve these values. The highly purified SWNTs have further been utilized to fabricate transparent and conducting SWNT films on glass and PET (polyethylene terephthalate) substrates by the filtration and PDMS stamping techniques. The measured transmittance and electrical resistance of SWNT film on PET substrate are comparable to indium tin oxide (ITO), but maintain stable electrical properties with bending.

Yu, Aiping

379

Brain activation during executive processes in schizophrenia  

Microsoft Academic Search

Schizophrenia patients show some deficits in executive processes (impaired behavioural performance and abnormal brain functioning). The aim of this study is to explore the brain activity of schizophrenia patients during different inhibitory tasks. We used functional magnetic resonance imaging to investigate to investigate the restraint and deletion aspects of inhibition in 19 patients with schizophrenia and 12 normal subjects during

Aurélie Royer; Fabien Christian Georges Schneider; Anne Grosselin; Jacques Pellet; Fabrice-Guy Barral; Bernard Laurent; Denis Brouillet; François Lang

2009-01-01

380

Processing of Color Words Activates Color Representations  

ERIC Educational Resources Information Center

Two experiments were conducted to investigate whether color representations are routinely activated when color words are processed. Congruency effects of colors and color words were observed in both directions. Lexical decisions on color words were faster when preceding colors matched the color named by the word. Color-discrimination responses…

Richter, Tobias; Zwaan, Rolf A.

2009-01-01

381

Waste management activities and carbon emissions in Africa.  

PubMed

This paper summarizes research into waste management activities and carbon emissions from territories in sub-Saharan Africa with the main objective of quantifying emission reductions (ERs) that can be gained through viable improvements to waste management in Africa. It demonstrates that data on waste and carbon emissions is poor and generally inadequate for prediction models. The paper shows that the amount of waste produced and its composition are linked to national Gross Domestic Product (GDP). Waste production per person is around half that in developed countries with a mean around 230 kg/hd/yr. Sub-Saharan territories produce waste with a biogenic carbon content of around 56% (+/-25%), which is approximately 40% greater than developed countries. This waste is disposed in uncontrolled dumps that produce large amounts of methane gas. Greenhouse gas (GHG) emissions from waste will rise with increasing urbanization and can only be controlled through funding mechanisms from developed countries. PMID:20832276

Couth, R; Trois, C

2011-01-01

382

Sorption of cobalt on activated carbons from aqueous solutions  

SciTech Connect

The efficiencies of 15 commercially available activated carbons were tested for the separation of trace cobalt ({sup 60}Co) in buffer solutions at pH 5.0, 6.7, and 9.1. On the basis of the results four carbon products, Diahope-006, Eurocarb TN5, Hydraffin DG47, and Norit ROW Supra, were selected for further study. These carbons represented varying (low, medium and high) cobalt removal efficiencies and were prepared of three typical raw materials: peat, coconut shell, or coal. Study was made of the effects on sorption efficiencies of factors of interest in metal/radionuclide-bearing waste effluents. These factors were pH, sodium ions, borate, and citrate.

Paajanen, A.; Lehto, J.; Santapakka, T.; Morneau, J.P. [Univ. of Helsinki (Finland)

1997-01-01

383

Active carbon filter health condition detection with piezoelectric wafer active sensors  

NASA Astrophysics Data System (ADS)

The impregnated active carbon used in air purification systems degrades over time due to exposure to contamination and mechanical effects (packing, settling, flow channeling, etc.). A novel approach is proposed to detect contamination in active carbon filters by combining the electromechanical impedance spectroscopy (EMIS) and electrochemical impedance spectroscopy (ECIS). ECIS is currently being used to evaluate active carbon filtration material; however, it cannot differentiate the impedance changes due to chemical contamination from those due to mechanical changes. EMIS can detect impedance changes due to mechanical changes. For the research work presented in this paper, Piezoelectric wafer active sensor (PWAS) was used for the EMIS method. Some remarkable new phenomena were unveiled in the detection of carbon filter status. 1. PWAS EMIS can detect the presence of contaminants, such as water and kerosene in the carbon bed 2. PWAS EMIS can monitor changes in mechanical pressure that may be associated with carbon bed packing, settling and flow channeling 3. EMIS and ECIS measurements are consistent with each other and complimentary A tentative simplified impedance model was created to simulate the PWAS-carbon bed system under increasing pressure. Similar impedance change pattern was observed when comparing the simulation results with experimental data.

Bao, Jingjing; Giurgiutiu, Victor; Rubel, Glenn O.; Peterson, Gregory W.; Ball, Thomas M.

2011-04-01

384

The transfer of modern organic Carbon by landslide activity in tropical montane ecosystems  

NASA Astrophysics Data System (ADS)

Geomorphic processes play an important role in the transfer and storage of Carbon within mountainous terrain. Among these, mass wasting stands out because of its impact on above and below-ground Carbon pools and its potential for releasing or sequestering Carbon. A combined remote-sensing and GIS approach was used to quantify the amount and spatial redistribution of modern organic Carbon mobilized by mass wasting activity in a tropical mountain setting. The study focused on a population of shallow landslides triggered by Hurricane Mitch (1998) on seven watersheds draining the southern flanks of the Sierra de Las Minas mountain range (SLM) in central Guatemala. Results illustrate that mass wasting contributed to the transfer of 43 x104 MgC, or 3% of the pre-event C in above-ground vegetation and soils for an equivalent Carbon flux rate of 0.08 to 0.33 MgC ha-1 y-1. The ultimate fate of the Carbon released by landsliding is very uncertain but depending on the proportion sequestered by colluvial deposits, mass wasting could be either a net source or sink of Carbon. In a simulated setting in which all Carbon transferred by landslides from all tropical mountains of the globe is released to the atmosphere, it would represent an amount equivalent to 1 - 11% of the global Carbon currently being released by the burning of fossil fuels. Meanwhile, in a scenario where a significant proportion of the Carbon transferred by landslides is retained within sedimentary deposits, sequestration rates would equal 2 - 19% of the residual land sink.

Ramos-Scharron, C.; Restrepo, C.

2012-04-01

385

Direct Observation of Completely Processed Calcium Carbonate Dust Particles  

SciTech Connect

This study presents, for the first time, field evidence of complete, irreversible processing of solid calcium carbonate (calcite)-containing particles and quantitative formation of liquid calcium nitrate particles apparently as a result of heterogeneous reaction of calcium carbonate-containing mineral dust particles with gaseous nitric acid. Formation of nitrates from individual calcite and sea salt particles was followed as a function of time in aerosol samples collected at Shoresh, Israel. Morphology and compositional changes of individual particles were observed using conventional scanning electron microscopy with energy dispersive analysis of X-rays (SEM/EDX) and computer controlled SEM/EDX. Environmental scanning electron microscopy (ESEM) was utilized to determine and demonstrate the hygroscopic behavior of calcium nitrate particles found in some of the samples. Calcium nitrate particles are exceptionally hygroscopic and deliquesce even at very low relative humidity (RH) of 9 -11% which is lower than typical atmospheric environments. Transformation of non-hygroscopic dry mineral dust particles into hygroscopic wet aerosol may have substantial impacts on light scattering properties, the ability to modify clouds and heterogeneous chemistry.

Laskin, Alexander; Iedema, Martin J.; Ichkovich, Aviad; Graber, Ellen R.; Taraniuk, Ilya; Rudich, Yinon

2005-05-27

386

Mechanical properties of laser processed diamond-like carbon films  

SciTech Connect

Diamond-like carbon (DLC) films have a unique combination of physical and chemical properties such as high hardness, optical transparency, low coefficient of friction and chemical inertness. A pulsed laser (248 nm) has been used to ablate a pyrolytic graphite target to deposit DLC films on Si (100) and 7059 Corning glass substrates. The deposition was carried out in high vacuum ({le} 10{sup {minus}6} Torr) at different temperatures ranging from room temperature to 400 C. The films were characterized by x-ray diffraction, scanning electron microscope, and Raman spectroscopic techniques. The mechanical properties (hardness and Young`s modulus) of these films were characterized by nanoindentation. The authors have found that the films deposited at room temperature and 100 C show the characteristic features of DLC films and have the better hardness and modulus properties compared to the films fabricated at higher temperatures, which transform into amorphous carbon. Correlations of pulsed laser deposition process parameters with the properties of deposited DLC films will be discussed in this paper.

Kumar, A.; Ekanayake, U.; Shu, N.; Kjendal, D.; Wattuhewa, G. [Univ. of South Alabama, Mobile, AL (United States). Dept. of Electrical Engineering; Barnard, J.A. [Univ. of Alabama, Tuscaloosa, AL (United States). Dept. of Metallurgical and Materials Engineering; Vohra, Y. [Univ. of Alabama, Birmingham, AL (United States). Dept. of Physics

1996-12-31

387

Preparation of activated carbon using low temperature carbonisation and physical activation of high ash raw bagasse for acid dye adsorption  

Microsoft Academic Search

Activated carbons were prepared from bagasse through a low temperature (160 °C) chemical carbonisation treatment and gasification with carbon dioxide at 900 °C. The merit of low temperature chemical carbonisation in preparing chars for activation was assessed by comparing the physical and chemical properties of activated carbons developed by this technique to conventional methods involving the use of thermal and

M. Valix; W. H. Cheung; G. McKay

2004-01-01

388

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

NASA Astrophysics Data System (ADS)

Electrochemical characterization has been carried out for electrodes prepared of several activated carbon fiber samples derived from poly ( m-phenylene isophthalamide) (Nomex) in an aqueous solution. Depending on the burn-off due to activation the BET surface area of the carbons was in the order of 1300-2800 m 2 g -1, providing an extensive network of micropores. Their capability as active material for supercapacitors was evaluated by using cyclic voltammetry and impedance spectroscopy. Values for the capacitance of 175 F g -1 in sulfuric acid were obtained. Further on, it was observed that the specific capacitance and the performance of the electrode increase significantly with increasing burn-off degree. We believe that this fact can be attributed to the increase of surface area and porosity with increasing burn-off.

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

389

Optimization of preparation conditions for activated carbons from coconut husk using response surface methodology  

Microsoft Academic Search

Coconut husk was used to prepare activated carbon using physiochemical activation method, consisted of potassium hydroxide (KOH) treatment and carbon dioxide (CO2) gasification. The effects of the preparation variables which were activation temperature, activation time and chemical impregnation (KOH:char) ratio on the adsorption capacity on methylene blue dye and carbon yield were investigated. Based on the central composite design (CCD),

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

2008-01-01

390

Water vapor adsorption onto activated carbons prepared from cattle manure compost (CMC)  

Microsoft Academic Search

Activated carbons were prepared from cattle manure compost (CMC) using zinc chloride activation. The structural and surface chemical characteristics of CMC-based activated carbons were determined by N2 adsorption–desorption and Boehm titration, respectively. The water vapor adsorption properties of the prepared activated carbons with various pore structure and surface nature were examined, and the mechanism of water adsorbed onto activated carbon

Qingrong Qian; Satoshi Sunohara; Yuichi Kato; Muhammad Abbas Ahmad Zaini; Motoi Machida; Hideki Tatsumoto

2008-01-01

391

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...municipal waste combustion unit uses activated carbon...calculate the carbon feed rate based on the operating...municipal waste combustion unit is operating and combusting...block average carbon feed rate in kilograms (or...

2013-07-01

392

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

Code of Federal Regulations, 2011 CFR

...monitor the injection rate of activated carbon...municipal waste combustion unit uses activated carbon...calculate the carbon feed rate based on the operating...municipal waste combustion unit is operating and combusting...block average carbon feed rate in kilograms (or...

2011-07-01

393

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

Code of Federal Regulations, 2010 CFR

...monitor the injection rate of activated carbon...municipal waste combustion unit uses activated carbon...calculate the carbon feed rate based on the operating...municipal waste combustion unit is operating and combusting...block average carbon feed rate in kilograms (or...

2010-07-01

394

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...municipal waste combustion unit uses activated carbon...calculate the carbon feed rate based on the operating...municipal waste combustion unit is operating and combusting...block average carbon feed rate in kilograms (or...

2013-07-01

395

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

Code of Federal Regulations, 2012 CFR

...monitor the injection rate of activated carbon...municipal waste combustion unit uses activated carbon...calculate the carbon feed rate based on the operating...municipal waste combustion unit is operating and combusting...block average carbon feed rate in kilograms (or...

2012-07-01

396

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

Code of Federal Regulations, 2011 CFR

...monitor the injection rate of activated carbon...municipal waste combustion unit uses activated carbon...calculate the carbon feed rate based on the operating...municipal waste combustion unit is operating and combusting...block average carbon feed rate in kilograms (or...

2011-07-01

397

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

Code of Federal Regulations, 2012 CFR

...monitor the injection rate of activated carbon...municipal waste combustion unit uses activated carbon...calculate the carbon feed rate based on the operating...municipal waste combustion unit is operating and combusting...block average carbon feed rate in kilograms (or...

2012-07-01

398

Laser ablation process for single-walled carbon nanotube production  

NASA Technical Reports Server (NTRS)

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.

Arepalli, Sivaram

2004-01-01

399

Diamagnetic studies on as-processed carbon fibers  

NASA Technical Reports Server (NTRS)

The Faraday method has been used to measure the diamagnetic susceptibilities of small bundles of aligned carbon fibers of different types at room temperature. It was found that the tensor trace susceptibility of the fibers varies systematically over the range 0.8-20 (in units of -10 to the -6th emu/g) as a function of precursor type and processing history. The susceptibility increases, in general, with increasing nominal treatment temperature and hot stretching, and with increasing tensile elastic modulus. The anisotropy ratio of fibers increases approximately linearly with tensile elastic modulus for all fibers from about 1 for a modulus of about 70 GN/sq m to about 22 for a modulus of 700 GN/sq m in air, and is quantitatively consistent with the layer-plane orientation textures determined by X-ray diffraction when appropriate values of the crystallite principal susceptibilities are used.

Scott, C. B.; Fischbach, D. B.

1976-01-01

400

Process for preparing raw material for producing carbon material  

SciTech Connect

The present invention relates to a process for preparing raw material containing small amount of quinoline-insoluble component for producing carbon material, comprising the steps of admixing a heavy oil of coal origin or of petroleum origin with an organic solvent having a boiling point of lower than 150/sup 0/ C. and a surfactant which is soluble in the heavy oil and has defoaming property and de-bubbling property, stirring the thus formed mixture gently with a motive power in a range of 0.5 to 50 watt/m/sup 3/ of the mixture, subjecting the mixture to centrifugation thereby removing the solid impurities, and distilling the remaining liquid thereby removing the light fraction to obtain the raw material.

Shigeta, M.; Hoshi, A.; Isii, Y.

1984-11-13

401

The activated sludge process: Fundamentals of operation  

SciTech Connect

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 Strength; Dissolved Oxygen; pH; Temperature; Nutrients; Toxicity; Mixing; Detention Time; Hydraulics; PROCESS MODIFICATIONS; Conventional; Complete Mix; Contact-Stabilization; Extended Aeration; Others; PROCESS MONITORING; Visual; Analytical Indicators; OPERATIONAL CONTROL; Sludge Volume Index; Sludge Age; Mean Cell Residence Time; Food/Microorganism Ratio; Organic Loading Rate; Solids Loading Rate; Clarifier Overflow Rate; Weir Overflow Rate; Sludge Recycle Rate, Sludge Wastage Rate; Chemical Feed Rate; TROUBLESHOOTING; Low BOD Removal; Low D.O. in Aeration Baisn; Poor Settling; PLANT START-UP; Introduction; Pre Start-up Checkup; Wastewater Analysis; Seed Screening; Process Checklist; Mechanical Checklist; Familiarization and Training; Start-up; Seeding; Process Monitoring; Transition; Typical Start-up Problems; Foaming; Settling Problems; Low BOD Removal; INDEX.

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

1983-01-01

402

Preparation of activated carbon from cattail and its application for dyes removal  

Microsoft Academic Search

Activated carbon was prepared from cattail by H3PO4 activation. The effects influencing the surface area of the resulting activated carbon followed the sequence of activated temperature > activated time > impregnation ratio > impregnation time. The optimum condition was found at an impregnation ratio of 2.5, an impregnation time of 9 hr, an activated temperature of 500°C, and an activated

Qianqian Shi; Jian Zhang; Chenglu Zhang; Cong Li; Bo Zhang; Weiwei Hu; Jingtao Xu; Ran Zhao

2010-01-01

403

Speech perception as an active cognitive process  

PubMed Central

One view of speech perception is that acoustic signals are transformed into representations for pattern matching to determine linguistic structure. This process can be taken as a statistical pattern-matching problem, assuming realtively stable linguistic categories are characterized by neural representations related to auditory properties of speech that can be compared to speech input. This kind of pattern matching can be termed a passive process which implies rigidity of processing with few demands on cognitive processing. An alternative view is that speech recognition, even in early stages, is an active process in which speech analysis is attentionally guided. Note that this does not mean consciously guided but that information-contingent changes in early auditory encoding can occur as a function of context and experience. Active processing assumes that attention, plasticity, and listening goals are important in considering how listeners cope with adverse circumstances that impair hearing by masking noise in the environment or hearing loss. Although theories of speech perception have begun to incorporate some active processing, they seldom treat early speech encoding as plastic and attentionally guided. Recent research has suggested that speech perception is the product of both feedforward and feedback interactions between a number of brain regions that include descending projections perhaps as far downstream as the cochlea. It is important to understand how the ambiguity of the speech signal and constraints of context dynamically determine cognitive resources recruited during perception including focused attention, learning, and working memory. Theories of speech perception need to go beyond the current corticocentric approach in order to account for the intrinsic dynamics of the auditory encoding of speech. In doing so, this may provide new insights into ways in which hearing disorders and loss may be treated either through augementation or therapy. PMID:24672438

Heald, Shannon L. M.; Nusbaum, Howard C.

2014-01-01

404

Hierarchical activated mesoporous phenolic-resin-based carbons for supercapacitors.  

PubMed

A series of hierarchical activated mesoporous carbons (AMCs) were prepared by the activation of highly ordered, body-centered cubic mesoporous phenolic-resin-based carbon with KOH. The effect of the KOH/carbon-weight ratio on the textural properties and capacitive performance of the AMCs was investigated in detail. An AMC prepared with a KOH/carbon-weight ratio of 6:1 possessed the largest specific surface area (1118?m(2) ?g(-1) ), with retention of the ordered mesoporous structure, and exhibited the highest specific capacitance of 260?F?g(-1) at a current density of 0.1?A?g(-1) in 1?M H2 SO4 aqueous electrolyte. This material also showed excellent rate capability (163?F?g(-1) retained at 20?A?g(-1) ) and good long-term electrochemical stability. This superior capacitive performance could be attributed to a large specific surface area and an optimized micro-mesopore structure, which not only increased the effective specific surface area for charge storage but also provided a favorable pathway for efficient ion transport. PMID:25100552

Wang, Zhao; Zhou, Min; Chen, Hao; Jiang, Jingui; Guan, Shiyou

2014-10-01

405

Insights into the Processing of Carbon by Early Microbial Ecosystems  

NASA Technical Reports Server (NTRS)

Interactions between Earth and the biosphere that were crucial for early biological evolution also influenced substantially the processes that circulate C between its reservoirs in the atmosphere, ocean, crust and mantle. The C-13 C-12 values of crustal carbonates and organics have recorded changes both in biological discrimination and in the relative rates of burial of organics and carbonates. A full interpretation of these patterns needs further isotopic studies of microbial ecosystems and individual anaerobes. Thus we measured carbon isotope discrimination during autotrophic and heterotrophic growth of pure cultures of sulfate-reducing bacteria and archaea (SRB and SRA). Discrimination during CO2 assimilation is significantly larger than during heterotrophic growth on lactate or acetate. SRB grown lithoautotrophically consumed less than 3% of available CO2 and exhibited substantial discrimination, as follows: Desulfobacterium autotrophicum (alpha 1.0100 to 1.0123), Desulfobacter hydrogenophilus (alpha = 0.0138), and Desulfotomuculum acetoxidans (alpha = 1.0310). Mixotrophic growth of Desulfovibrio desulfuricans on acetate and CO2 resulted in biomass with delta C-13 composition intermediate to that of the substrates. We have recently extended these experiments to include the thermophilic SRA Archeoglobus spp. Ecological forces also influence isotopic discrimination. Accordingly, we quantified the flow of C and other constituents in modern marine cyanobacterial mats, whose ancestry extends back billions of years. Such ecosystem processes shaped the biosignatures that entered sediments and atmospheres. At Guerrero Negro, BCS, Mexico, we examined mats dominated by Microcoleus (subtidal) and Lyngbya (intertidal to supratidal) cyanobacteria. During 24 hour cycles, we observed the exchange of O2 and dissolved inorganic C (DIC) between mats and the overlying water. Microcoleus mats assimilated near-equal amounts of DIC during the day as they released at night, but Lyngbya mats typically showed net uptake of DIC over the diel cycle. Patterns of O2 daytime release and nighttime uptake mirrored these DIC trends in both mat types. Nighttime DIC effluxes from Microcoleus mats were equivalent in the presence versus absence of O2, whereas nighttime DIC effluxes from Lyngbya mats dropped markedly in the absence of O2. Thus aerobic diagenesis was more important in Lyngbya mats than in Microcoleus mats, perhaps because trapped O2 bubbles persist only in Lyngbya mats at night and thus sustain populations of aerbes. In both mat types, effluxes of H2, CH4 and short-chain fatty acids were much greater at night in the absence of 02, emphasizing the importance of fermentation. Differences observed between Microcoleus versus Lyngbya mats forecast differences in their microbial populations and in their patterns of gene expression.

DesMarais, D.; Bebout, B.; Carpenter, S.; Discipulo, S.; Londry, K.; Habicht, K.; Turk, K.

2003-01-01

406

Activation and micropore structure determination of activated carbon-fiber composites  

SciTech Connect

Rigid, high surface area activated carbon fiber composites have been produced with high permeabilities for environmental applications in gas and water purification. These novel monolithic adsorbents can be produced in single pieces to a given size and shape. The project involves a collaboration between the Oak Ridge National Laboratory (ORNL) and the Center for Applied Energy Research (CAER), University of Kentucky. The carbon fiber composites are produced at the ORNL and activated at the CAER using different methods, with the aims of producing a uniform degree of activation, and of closely controlling pore structure and adsorptive properties. The main focus of the present work has been to find a satisfactory means to uniformly activate large samples of carbon fiber composites and produce controlled pore structures. Several environmental applications have been explored for the activated carbon fiber composites. One of these was to evaluate the activated composites for the separation of CH{sub 4}-CO{sub 2} mixtures, and an apparatus was constructed specifically for this purpose. The composites were further evaluated in the cyclic recovery of volatile organics. The activated carbon fiber composites have also been tested for possible water treatment applications by studying the adsorption of sodium pentachlorophenolate, PCP.

Jagtoyen, M.; Derbyshire, F.; Kimber, G. [Univ. of Kentucky, Lexington, KY (United States). Center for Applied Energy Research

1997-09-05

407

The removal of uranium (VI) from aqueous solutions onto activated carbon developed from grinded used tire.  

PubMed

In this study, activated carbon was prepared from waste tire by KOH chemical activation. The pore properties including the BET surface area, pore volume, pore size distribution, and average pore diameter were characterized. BET surface area of the activated carbon was determined as 558 m(2)/g. The adsorption of uranium ions from the aqueous solution using this activated carbon has been investigated. Various physico-chemical parameters such as pH, initial metal ion concentration, and adsorbent dosage level and equilibrium contact time were studied by a batch method. The optimum pH for adsorption was found to be 3. The removal efficiency has also been determined for the adsorption system as a function of initial concentration. The experimental results were fitted to Langmuir, Freundlich, and Dubinin-Radushkevich (D-R) isotherm models. A comparison of best-fitting was performed using the coefficient of correlation and the Langmuir isotherm was found to well represent the measured sorption data. According to the evaluation using the Langmuir equation, the saturated monolayer sorption capacity of uranium ions onto waste tire activated carbon was 158.73 mg/g. The thermodynamic equilibrium constant and the Gibbs free energy were determined and results indicated the spontaneous nature of the adsorption process. Kinetics data were best described by pseudo-second-order model. PMID:23821251

Belgacem, Ahmed; Rebiai, Rachid; Hadoun, Hocine; Khemaissia, Sihem; Belmedani, Mohamed

2014-01-01

408

Controlling contagion processes in activity driven networks.  

PubMed

The vast majority of strategies aimed at controlling contagion processes on networks consider the connectivity pattern of the system either quenched or annealed. However, in the real world, many networks are highly dynamical and evolve, in time, concurrently with the contagion process. Here, we derive an analytical framework for the study of control strategies specifically devised for a class of time-varying networks, namely activity-driven networks. We develop a block variable mean-field approach that allows the derivation of the equations describing the coevolution of the contagion process and the network dynamic. We derive the critical immunization threshold and assess the effectiveness of three different control strategies. Finally, we validate the theoretical picture by simulating numerically the spreading process and control strategies in both synthetic networks and a large-scale, real-world, mobile telephone call data set. PMID:24702426

Liu, Suyu; Perra, Nicola; Karsai, Márton; Vespignani, Alessandro

2014-03-21

409

Controlling Contagion Processes in Activity Driven Networks  

NASA Astrophysics Data System (ADS)

The vast majority of strategies aimed at controlling contagion processes on networks consider the connectivity pattern of the system either quenched or annealed. However, in the real world, many networks are highly dynamical and evolve, in time, concurrently with the contagion process. Here, we derive an analytical framework for the study of control strategies specifically devised for a class of time-varying networks, namely activity-driven networks. We develop a block variable mean-field approach that allows the derivation of the equations describing the coevolution of the contagion process and the network dynamic. We derive the critical immunization threshold and assess the effectiveness of three different control strategies. Finally, we validate the theoretical picture by simulating numerically the spreading process and control strategies in both synthetic networks and a large-scale, real-world, mobile telephone call data set.

Liu, Suyu; Perra, Nicola; Karsai, Márton; Vespignani, Alessandro

2014-03-01

410

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

PubMed

A hybrid electrode material for high-power supercapacitors was fabricated by grafting carbon nanofibers (CNFs) onto the surface of powdered activated carbon (AC) through catalytic chemical vapor deposition (CCVD). A uniform thin layer of disentangled CNFs with a herringbone structure was deposited on the carbon surface through the decomposition of propane at 450?°C over an AC-supported nickel catalyst. CNF coating was controlled by the reaction time and the nickel content. The superior CNF/AC composite displays excellent electrochemical performance in a 0.5 mol L(-1) solution of K2 SO4 due to its unique structure. At a high scan rate (100 mV s(-1) ) and current loading (20 A g(-1) ), the capacitance values were three- and fourfold higher than those for classical AC/carbon black composites. Owing to this feature, a high energy of 10 Wh kg(-1) was obtained over a wide power range in neutral medium at a voltage of 0.8 V. The significant enhancement of charge propagation is attributed to the presence of herringbone CNFs, which facilitate the diffusion of ions in the electrode and play the role of electronic bridges between AC particles. An in situ coating of AC with short CNFs (below 200 nm) is a very attractive method for producing the next generation of carbon composite materials with a high power performance in supercapacitors working in neutral medium. PMID:23794416

Gryglewicz, Gra?yna; ?liwak, Agata; Béguin, François

2013-08-01

411

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. The largest applications are those which support metals smelting, such as anodes for aluminum smelting and electrodes for arc furnaces. Other carbon products include materials used in creating fuels for the Direct Carbon Fuel Cell, 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 carbon electrodes for Direct Carbon Fuel Cells (DCFC), and on carbon foam composites used in ballistic armor, as well as the hydrotreatment of solvents used in the basic solvent extraction process. A major goal is the production of 1500 pounds of binder pitch, corresponding to about 3000 pounds of hydrotreated solvent.

Elliot B. Kennel; Quentin C. Berg; Stephen P. Carpenter; Dady Dadyburjor; Jason C. Hissam; Manoj Katakdaunde; Liviu Magean; Abha Saddawi; Alfred H. Stiller; John W. Zondlo

2006-03-07

412

Application of activated carbon derived from scrap tires for adsorption of Rhodamine B.  

PubMed

Activated carbon derived from solid hazardous waste scrap tires was evaluated as a potential adsorbent for cationic dye removal. The adsorption process with respect to operating parameters was investigated to evaluate the adsorption characteristics of the activated pyrolytic tire char (APTC) for Rhodamine B (RhB). Systematic research including equilibrium, kinetics and thermodynamic studies was performed. The results showed that APTC was a potential adsorbent for RhB with a higher adsorption capacity than most adsorbents. Solution pH and temperature exert significant influence while ionic strength showed little effect on the adsorption process. The adsorption equilibrium data obey Langmuir isotherm and the kinetic data were well described by the pseudo second-order kinetic model. The adsorption process followed intra-particle diffusion model with more than one process affecting the adsorption process. Thermodynamic study confirmed that the adsorption was a physisorption process with spontaneous, endothermic and random characteristics. PMID:21179969

Li, Li; Liu, Shuangxi; Zhu, Tan

2010-01-01

413

Processable Conducting Polyaniline, Carbon Nanotubes, Graphene and Their Composites  

NASA Astrophysics Data System (ADS)

Good processability is often required for applications of conducting materials like polyaniline (PANI), carbon nanotubes (CNTs) and graphene. This can be achieved by either physical stabilization or chemical functionalization. Functionalization usually expands the possible applications for the conducting materials depending on the properties of the functional groups. Processable conducting materials can also be combined with other co-dissolving materials to prepare composites with desired chemical and physical properties. Polyanilines (PANI) doped with dodecylbenzenesulfonic acid (DBSA) are soluble in many organic solvents such as chloroform and toluene. Single wall carbon nanotubes (SWCNTs) can be dispersed into PANI/DBSA to form homogeneous solutions. PANI/DBSA functions as a conducting surfactant for SWCNTs. The mixture can be combined with two-parts polyurethanes that co-dissolve in the organic solvent to produce conducting polymer composites. The composite mixtures can be applied onto various substrates by simple spray-on methods to obtain transparent and conducting coatings. Graphene, a single layer of graphite, has drawn intense interest for its unique properties. Processable graphene has been produced in N-methyl-2-pyrrolidone (NMP) by a one-step solvothermal reduction of graphite oxide without the aid of any reducing reagent and/or surfactant. The as-synthesized graphene disperses well in a variety of organic solvents such as dimethylsulfoxide (DMSO), ethanol and tetrahydrogenfuran (THF). The conductivity of solvothermal reduced graphite oxide is comparable to hydrazine reduced graphite oxide. Attempts were made to create intrinsically conducting glue comparable to mussel adhesive protiens using polyaniline and graphene. Mussels can attach to a variety of substrates under water. Catechol residue in 3,4-dihydroxyphenylalanine (L-DOPA) is the key to the wet adhesion. Tyrosine and phosphoserine with primary alkyl amine groups also participate in adhesion. A novel water soluble synthetic mussel adhesive containing both catechol and amine groups are synthesized in a simple approach. A polyallylamine backbone is used to take the place of the polyamide chain. Catechol is appended to the backbone as the key cross-linking group. Compared to polyallyamine, poly[N-(3,4- dihydroxybenzylidene)allylamine] exhibits good adhesion under alkaline water due to moderate cross-linking. When exposed to cross-linkers, this synthetic mussel adhesive can form a hydrogel at a very low concentration. Various methods were tried to attach catechol group onto polyaniline and graphene to make synthetic conductive mussel adhesive. Although the chemistry proved to be successful, the material doesn't show great adhesion to selected substrates probably due the nature of the backbone and difficulties associated with its processability

Wang, Kan

414

Removal of copper and cadmium from aqueous solution using switchgrass biochar produced via hydrothermal carbonization process.  

PubMed

Biochar produced from switchgrass via hydrothermal carbonization (HTC) was used as a sorbent for the removal of copper and cadmium from aqueous solution. The cold activation process using KOH at room temperature was developed to enhance the porous structure and sorption properties of the HTC biochar. The sorption efficiency of HTC biochar and alkali activated HTC biochar (HTCB) for removing copper and cadmium from aqueous solution were compared with commercially available powdered activated carbon (PAC). The present batch adsorption study describes the effects of solution pH, biochar dose, and contact time on copper and cadmium removal efficiency from single metal ion aqueous solutions. The activated HTCB exhibited a higher adsorption potential for copper and cadmium than HTC biochar and PAC. Experiments conducted with an initial metal concentration of 40 mg/L at pH 5.0 and contact time of 24 h resulted in close to 100% copper and cadmium removal by activated HTCB at 2 g/L, far greater than what was observed for HTC biochar (16% and 5.6%) and PAC (4% and 7.7%). The adsorption capacities of activated HTCB for cadmium removal were 34 mg/g (0.313 mmol/g) and copper removal was 31 mg/g (0.503 mmol/g). PMID:22687632

Regmi, Pusker; Garcia Moscoso, Jose Luis; Kumar, Sandeep; Cao, Xiaoyan; Mao, Jingdong; Schafran, Gary

2012-10-30

415

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

PubMed

Large quantities of lignocellulosic residues result from the industrial production of essential oil from vetiver grass (Vetiveria zizanioides) roots. These residues could be used for the production of activated carbon. The yield of char obtained after vetiver roots pyrolysis follows an equation recently developed [A. Ouensanga, L. Largitte, M.A. Arsene, The dependence of char yield on the amounts of components in precursors for pyrolysed tropical fruit stones and seeds, Micropor. Mesopor. Mater. 59 (2003) 85-91]. The N(2) adsorption isotherm follows either the Freundlich law K(F)P(alpha) which is the small alpha equation limit of a Weibull shaped isotherm or the classical BET isotherm. The surface area of the activated carbons are determined using the BET method. The K(F) value is proportional to the BET surface area. The alpha value increases slightly when the burn-off increases and also when there is a clear increase in the micropore distribution width. PMID:17092643

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

2007-06-01

416

PRODUCTION OF CARBON PRODUCTS USING A COAL EXTRACTION PROCESS  

Microsoft Academic Search

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

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

2004-01-01

417

Facile fabrication of magnetic carbon composites from hydrochar via simultaneous activation and magnetization for triclosan adsorption.  

PubMed

Advanced magnetic carbon composites with high specific surface area and high microporosity are required for both environmentally and agriculturally related applications. However, more research is needed for the development of a facile and highly efficient synthesis process. In the present work, a novel approach of simultaneous activation and magnetization is proposed for the fabrication of magnetic carbon composites via the thermal pyrolysis of hydrochar (i.e., a solid residue from a hydrothermal carbonization process) that has been pretreated with mixtures of ferric chloride (FeCl3) and zinc chloride (ZnCl2). The main objective of this study is the investigation of the variation of characteristics of magnetic carbon composites produced at various conditions, as well as triclosan (TCS) adsorption behavior on such composites. This presented simple one-step synthesis method has the following advantages: (a) the hydrochar is activated with high surface area and pore volume (up to 1351 m(2)/g and 0.549 cm(3)/g, respectively), (b) activation and magnetization are simultaneously achieved without further modification, (c) the magnetic particles (?-Fe2O3) are stable under an acidic medium (pH of 3.0 and 4.0), and (d) the products have the potential to remove TCS from aqueous solutions with a maximum adsorption capacity of 892.9 mg/g. The results indicate the effectiveness of this facile synthesis strategy in converting low-value biowaste into a functional material with high performance for pollutant removal from aqueous solutions. PMID:24738924

Zhu, Xiangdong; Liu, Yuchen; Luo, Gang; Qian, Feng; Zhang, Shicheng; Chen, Jianmin

2014-05-20

418

Carbon-Based Supercapacitors Produced by Activation of Graphene  

Microsoft Academic Search

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,

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

2011-01-01

419

76 FR 60803 - Fourth Administrative Review of Certain Activated Carbon From the People's Republic of China...  

Federal Register 2010, 2011, 2012, 2013

...A-570-904] Fourth Administrative Review of Certain Activated Carbon From the People's Republic of China: Extension...initiation of an administrative review of certain activated carbon from the People's Republic of China...

2011-09-30

420

Penyediaan dan pencirian karbon aktif. (Preparation and characterization of activated carbon).  

National Technical Information Service (NTIS)

Activated carbon was prepared from Agricultural wastes, such as coconut shell, Palm oil Shell and mangrove trunk by destructive distillation under vakuum. Chemical and Physical properties of the activated carbon were studied and some potentially useful ap...

Badri bin Muhammad Karen binti Badri Mohd Zobir bin Hussein Zulkarnain bin Zainal, W.M. Daud bin W Yunus

1994-01-01

421

KOH catalysed preparation of activated carbon aerogels for dye adsorption  

Microsoft Academic Search

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

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

2011-01-01

422

Elucidation of an Iterative Process of Carbon-Carbon Bond Formation of Prebiotic Significance  

NASA Astrophysics Data System (ADS)

Laboratory experiments carried out under plausible prebiotic conditions (under conditions that might have occurred at primitive deep-sea hydrothermal vents) in water and involving constituents that occur in the vicinity of submarine hydrothermal vents (e.g., CO, H2S, NiS) have disclosed an iterative Ni-catalyzed pathway of C-C bond formation. This pathway leads from CO to various organic molecules that comprise, notably, thiols, alkylmono- and disulfides, carboxylic acids, and related thioesters containing up to four carbon atoms. Furthermore, similar experiments with organic compounds containing various functionalities, such as thiols, carboxylic acids, thioesters, and alcohols, gave clues to the mechanisms of this novel synthetic process in which reduced metal species, in particular Ni(0), appear to be the key catalysts. Moreover, the formation of aldehydes (and ketones) as labile intermediates via a hydroformylation-related process proved to be at the core of the chain elongation process. Since this process can potentially lead to organic compounds with any chain length, it could have played a significant role in the prebiotic formation of lipidic amphiphilic molecules such as fatty acids, potential precursors of membrane constituents.

Loison, Aurélie; Dubant, Stéphane; Adam, Pierre; Albrecht, Pierre

2010-12-01

423

Liquid Phase Adsorption of ?-Tocopherol by Activated Carbon  

NASA Astrophysics Data System (ADS)

?-Tocopherol or commonly called vitamin E can be found in major commercial vegetable oils such as soya oil and palm oil. However the existence in these oil is in low concentration. The recovery of low concentration of ?-tocopherol from palm oils is increasingly popular. Adsorption technique for the recovery of ?-tocopherol from palm oil is believed to be much lower in cost and more effective. As a case study in this work, activated carbon is chosen as the adsorbent and ethanol as the solvent. The adsorption equilibria of ?-tocopherol onto activated carbon was conducted in batch and the concentration of ?-tocopherol was identified by LCMS. Langmuirian monolayer adsorption theory was used for the analysis of the isotherm equilibria. The adsorptivity of ?-tocopherol onto activated carbon was identified. The adsorption equilibria at low concentration found to be linear. The breakthrough curve was then generated using model assuming isothermal, single transition trace component with intraparticle diffusion. Sensitivity test on the curve indicated that the system is very sensitive to changes in diffusitivity and passive to changes on the equilibrium constant.

Bono, Awang; Ming, Chu Chi; Sundang, Murni