Modeling and Experimental Studies of Mercury Oxidation and Adsorption in a Fixed-Bed Reactor

Energy Technology Data Exchange (ETDEWEB)

Buitrago, Paula A.; Morrill, Mike; Lighty, JoAnn S.; Silcox, Geoffrey D.

2009-06-15

This report presents experimental and modeling mercury oxidation and adsorption data. Fixed-bed and single-particle models of mercury adsorption were developed. The experimental data were obtained with two reactors: a 300-W, methane-fired, tubular, quartz-lined reactor for studying homogeneous oxidation reactions and a fixed-bed reactor, also of quartz, for studying heterogeneous reactions. The latter was attached to the exit of the former to provide realistic combustion gases. The fixed-bed reactor contained one gram of coconut-shell carbon and remained at a temperature of 150°C. All methane, air, SO₂, and halogen species were introduced through the burner to produce a radical pool representative of real combustion systems. A Tekran 2537A Analyzer coupled with a wet conditioning system provided speciated mercury concentrations. At 150°C and in the absence of HCl or HBr, the mercury uptake was about 20%. The addition of 50 ppm HCl caused complete capture of all elemental and oxidized mercury species. In the absence of halogens, SO₂ increased the mercury adsorption efficiency to up to 30 percent. The extent of adsorption decreased with increasing SO₂ concentration when halogens were present. Increasing the HCl concentration to 100 ppm lessened the effect of SO₂. The fixed-bed model incorporates Langmuir adsorption kinetics and was developed to predict adsorption of elemental mercury and the effect of multiple flue gas components. This model neglects intraparticle diffusional resistances and is only applicable to pulverized carbon sorbents. It roughly describes experimental data from the literature. The current version includes the ability to account for competitive adsorption between mercury, SO₂, and NO₂. The single particle model simulates in-flight sorbent capture of elemental mercury. This model was developed to include Langmuir and Freundlich isotherms, rate equations, sorbent feed rate, and

Mercury adsorption characteristics of HBr-modified fly ash in an entrained-flow reactor.

Science.gov (United States)

Zhang, Yongsheng; Zhao, Lilin; Guo, Ruitao; Song, Na; Wang, Jiawei; Cao, Yan; Orndorff, William; Pan, Wei-ping

2015-07-01

In this study, the mercury adsorption characteristics of HBr-modified fly ash in an entrained-flow reactor were investigated through thermal decomposition methods. The results show that the mercury adsorption performance of the HBr-modified fly ash was enhanced significantly. The mercury species adsorbed by unmodified fly ash were HgCl2, HgS and HgO. The mercury adsorbed by HBr-modified fly ash, in the entrained-flow reactor, existed in two forms, HgBr2 and HgO, and the HBr was the dominant factor promoting oxidation of elemental mercury in the entrained-flow reactor. In the current study, the concentration of HgBr2 and HgO in ash from the fine ash vessel was 4.6 times greater than for ash from the coarse ash vessel. The fine ash had better mercury adsorption performance than coarse ash, which is most likely due to the higher specific surface area and longer residence time. Copyright © 2015. Published by Elsevier B.V.

Modeling and Experimental Studies of Mercury Oxidation and Adsorption in a Fixed-Bed and Entrained-Flow Reactor

Energy Technology Data Exchange (ETDEWEB)

Buitrago, Paula A. [Univ. of Utah, Salt Lake City, UT (United States); Morrill, Mike [Univ. of Utah, Salt Lake City, UT (United States); Lighty, JoAnn S. [Univ. of Utah, Salt Lake City, UT (United States); Silcox, Geoffrey D. [Univ. of Utah, Salt Lake City, UT (United States)

2009-06-01

This report presents experimental and modeling mercury oxidation and adsorption data. Fixed-bed and single-particle models of mercury adsorption were developed. The experimental data were obtained with two reactors: a 300-W, methane-fired, tubular, quartz-lined reactor for studying homogeneous oxidation reactions and a fixed-bed reactor, also of quartz, for studying heterogeneous reactions. The latter was attached to the exit of the former to provide realistic combustion gases. The fixed-bed reactor contained one gram of coconut-shell carbon and remained at a temperature of 150°C. All methane, air, SO₂, and halogen species were introduced through the burner to produce a radical pool representative of real combustion systems. A Tekran 2537A Analyzer coupled with a wet conditioning system provided speciated mercury concentrations. At 150°C and in the absence of HCl or HBr, the mercury uptake was about 20%. The addition of 50 ppm HCl caused complete capture of all elemental and oxidized mercury species. In the absence of halogens, SO₂ increased the mercury adsorption efficiency to up to 30 percent. The extent of adsorption decreased with increasing SO₂ concentration when halogens were present. Increasing the HCl concentration to 100 ppm lessened the effect of SO₂. The fixed-bed model incorporates Langmuir adsorption kinetics and was developed to predict adsorption of elemental mercury and the effect of multiple flue gas components. This model neglects intraparticle diffusional resistances and is only applicable to pulverized carbon sorbents. It roughly describes experimental data from the literature. The current version includes the ability to account for competitive adsorption between mercury, SO₂, and NO₂. The single particle model simulates in-flight sorbent capture of elemental mercury. This model was developed to include Langmuir and Freundlich isotherms, rate equations, sorbent feed rate, and

Study of the adsorption of mercury (II) on lignocellulosic materials under static and dynamic conditions.

Science.gov (United States)

Arias Arias, Fabian E; Beneduci, Amerigo; Chidichimo, Francesco; Furia, Emilia; Straface, Salvatore

2017-08-01

WHO has declared mercury as one of the most dangerous pollutants for human health. Unfortunately, several cases of rivers and aquifers contaminated by mercury inevitably poses the problem on how to remediate them. Considerable efforts are being addressed to develop cost-effective methodologies, among which the use of low-cost adsorbing materials. In this paper, the adsorption performances of an alternative lignocellulosic material derived from the Spanish broom plant, are presented. This plant is widely diffused in the world and its usage for Hg(II) removal from water in real working conditions requires only minimal pretreatment steps. A thoroughly investigation on the kinetics and thermodynamics of Hg(II) adsorption on Spanish broom is presented, by using Hg(II) polluted aqueous solutions specifically prepared in order to simulate typical groundwater conditions. Several batch experiments, under static conditions, were carried out in order to evaluate the effect of pH, contact time, adsorbent dosage, initial concentration, temperature. A maximum adsorption capacity of 20 mg L -1 can be obtained at pH 5, following a pseudo second order kinetics. Moreover, adsorption experiments in dynamic conditions were carried out using Spanish broom filters. Interestingly, a systematic, unconventional double S-shape breakthrough curve was observed under different experimental conditions, revealing the occurrence of two adsorption processes with different time scales. This behavior has been fitted by a bimodal Thomas model which, unlike the single Thomas fitting, gives satisfactory results with the introduction of a new parameter related to the fraction of surface active sites involved in the adsorption processes. Copyright © 2017 Elsevier Ltd. All rights reserved.

Mechanistic studies of mercury adsorption and oxidation by oxygen over spinel-type MnFe{sub 2}O{sub 4}

Energy Technology Data Exchange (ETDEWEB)

Yang, Yingju [State Key Laboratory of Coal Combustion, School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China); Liu, Jing, E-mail: liujing27@mail.hust.edu.cn [State Key Laboratory of Coal Combustion, School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China); Shenzhen Institute of Huazhong University of Science and Technology, Shenzhen 518000 (China); Zhang, Bingkai; Liu, Feng [State Key Laboratory of Coal Combustion, School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China)

2017-01-05

Highlights: • Hg adsorption and oxidation mechanisms on MnFe{sub 2}O{sub 4} were studied using DFT method. • Hg{sup 0} adsorption on Mn-terminated MnFe{sub 2}O{sub 4} (100) surface is a chemisorption process. • HgO shows high chemical reactivity for its adsorption on MnFe{sub 2}O{sub 4} surface. • The reaction between adsorbed Hg and surface oxygen is the rate-determining step. - Abstract: MnFe{sub 2}O{sub 4} has been regarded as a very promising sorbent for mercury emission control in coal-fired power plants because of its high adsorption capacity, magnetic, recyclable and regenerable properties. First-principle calculations based on density functional theory (DFT) were used to elucidate the mercury adsorption and oxidation mechanisms on MnFe{sub 2}O{sub 4} surface. DFT calculations show that Mn-terminated MnFe{sub 2}O{sub 4} (1 0 0) surface is much more stable than Fe-terminated surface. Hg{sup 0} is physically adsorbed on Fe-terminated MnFe{sub 2}O{sub 4} (1 0 0) surface. Hg{sup 0} adsorption on Mn-terminated MnFe{sub 2}O{sub 4} (1 0 0) surface is a chemisorption process. The partial density of states (PDOS) analysis indicates that Hg atom interacts strongly with surface Mn atoms through the orbital hybridization. HgO is adsorbed on the MnFe{sub 2}O{sub 4} surface in a chemical adsorption manner. The small HOMO–LUMO energy gap implies that HgO molecular shows high chemical reactivity for HgO adsorption on MnFe{sub 2}O{sub 4} surface. The energy barriers of Hg{sup 0} oxidation by oxygen on Fe- and Mn-terminated MnFe{sub 2}O{sub 4} surfaces are 206.37 and 76.07 kJ/mol, respectively. Mn-terminated surface is much more favorable for Hg{sup 0} oxidation than Fe-terminated surface. In the whole Hg{sup 0} oxidation process, the reaction between adsorbed mercury and surface oxygen is the rate-determining step.

Vapor-phase elemental mercury adsorption by Ca(OH){sub 2} impregnated with MnO{sub 2} and Ag in fixed-bed system

Energy Technology Data Exchange (ETDEWEB)

Y.J. Wang; Y.F. Duan; Z.J. Huang; S.L. Meng; L.G. Yang; C.S. Zhao [Southeast University, Nanjing (China). School of Energy and Environment

2010-05-15

The ability of three sorbents (untreated Ca(OH){sub 2}, MnO{sub 2}-impregnated Ca(OH){sub 2} and Ag-impregnated Ca(OH){sub 2}) removing the elemental mercury had been studied using a laboratory-scale fixed-bed reactor at 80{sup o}C under simulated fuel gas conditions. The adsorption performance of the three sorbents was compared by mercury removal efficiency and adsorption capacity. The effect of acid gases such as HCl and SO{sub 2} on the mercury removal was investigated and presented in this article. The results showed that the mercury removal by Ca(OH){sub 2} was mainly controlled by physical mechanisms. In the case of Ca(OH){sub 2}, the presence of both SO{sub 2} and HCl promoted the Hg{sup 0} removal, and compared HCl with SO{sub 2}, HCl had a higher mercury removal than SO{sub 2}. Ca(OH){sub 2} impregnated with MnO{sub 2} had a slightly higher mercury removal than the original Ca(OH){sub 2}, but it was beneficial for mercury speciation. The presence of both SO{sub 2} and HCl promotes the Hg0 removal greatly, which was adsorbed by Ca(OH){sub 2} impregnated with MnO{sub 2}. The Ca(OH){sub 2} impregnated with MnO{sub 2} adsorbed more than 50% total Hg due to the occurrence of chemisorptions. The mercury removal by Ca(OH){sub 2} impregnated with Ag was the highest. This may be because mercury integrated with silver easily that could produce silver amalgam alloy.

Fixed-bed studies of the interactions between mercury and coal combustion fly ash

Energy Technology Data Exchange (ETDEWEB)

Dunham, Grant E.; DeWall, Raymond A. [Energy and Environmental Research Center, 15 North 23rd Street, Grand Forks, ND 58203 (United States); Senior, Constance L. [Reaction Engineering International, 77 West 200 South, Suite 210, Salt Lake City, UT 84101 (United States)

2003-08-15

Sixteen different fly ash samples, generated from both pilot-scale and full-scale combustion systems, were exposed to a simulated flue gas containing either elemental mercury or HgCl{sub 2} in a bench-scale reactor system at the Energy and Environmental Research Center to evaluate the interactions and determine the effects of temperature, mercury species, and ash type on adsorption of mercury and oxidation of elemental mercury. The fly ash samples were characterized for surface area, loss on ignition, and forms of iron in the ash. While many of the ash samples oxidized elemental mercury, not all of the samples that oxidized mercury also captured elemental mercury. However, no capture of elemental mercury was observed without accompanying oxidation. Generally, oxidation of elemental mercury increased with increasing amount of magnetite in the ash. However, one high-carbon subbituminous ash with no magnetite showed considerable mercury oxidation that may have been due to unburned carbon. Surface area as well as the nature of the surface appeared to be important for oxidation and adsorption of elemental mercury. The capacity of the ash samples for HgCl{sub 2} was similar to that for elemental mercury. There was a good correlation between the capacity for HgCl{sub 2} and the surface area; capacity decreased with increasing temperature.

Sorption of mercury by activated carbon in the presence of flue gas components

International Nuclear Information System (INIS)

Diamantopoulou, Ir.; Skodras, G.; Sakellaropoulos, G.P.

2010-01-01

The purpose of the current study is to evaluate the mercury removal ability of F400 and Norit FGD activated carbons, through fixed bed adsorption tests at inert atmosphere (Hg + N 2 ). Additionally, adsorption tests were realized on F400 activated carbon, in the presence of HCl, O 2 , SO 2 and CO 2 in nitrogen flow. The obtained results, revealed that F400 activated carbon, with a high-developed micropore structure and increased BET area, exhibit larger Hg adsorptive capacity compared to Norit. HCl and O 2 , can strongly affect mercury adsorption, owing to heterogeneous oxidation and chemisorption reactions, which is in accordance with the assumptions of some researchers. Additionally, SO 2 presence enhances mercury adsorption, in contrast with the conclusions evaluated in other studies. The above result could be attributed to the possible formation of sulphur spaces on activated carbon surface and consist of a clarification for the role of SO 2 on mercury adsorption. On the contrary, the mercury adsorption efficiency of F400 activated carbon showed a decrease at about 25%, with increasing CO 2 concentration from 0 to 12%. (author)

Sorption of mercury by activated carbon in the presence of flue gas components

Energy Technology Data Exchange (ETDEWEB)

Diamantopoulou, Ir. [Chemical Process Engineering Laboratory, Department of Chemical Engineering, Aristotle University of Thessaloniki, Thessaloniki (Greece); Skodras, G. [Institute for Solid Fuels Technology and Applications, Ptolemais (Greece); Sakellaropoulos, G.P. [Chemical Process Engineering Laboratory, Department of Chemical Engineering, Aristotle University of Thessaloniki, Thessaloniki (Greece); Laboratory of Energy and Environmental Processes, Chemical Process Engineering Research Institute, Thessaloniki (Greece)

2010-02-15

The purpose of the current study is to evaluate the mercury removal ability of F400 and Norit FGD activated carbons, through fixed bed adsorption tests at inert atmosphere (Hg + N{sub 2}). Additionally, adsorption tests were realized on F400 activated carbon, in the presence of HCl, O{sub 2}, SO{sub 2} and CO{sub 2} in nitrogen flow. The obtained results, revealed that F400 activated carbon, with a high-developed micropore structure and increased BET area, exhibit larger Hg adsorptive capacity compared to Norit. HCl and O{sub 2}, can strongly affect mercury adsorption, owing to heterogeneous oxidation and chemisorption reactions, which is in accordance with the assumptions of some researchers. Additionally, SO{sub 2} presence enhances mercury adsorption, in contrast with the conclusions evaluated in other studies. The above result could be attributed to the possible formation of sulphur spaces on activated carbon surface and consist of a clarification for the role of SO{sub 2} on mercury adsorption. On the contrary, the mercury adsorption efficiency of F400 activated carbon showed a decrease at about 25%, with increasing CO{sub 2} concentration from 0 to 12%. (author)

Memory effects on adsorption tubes for mercury vapor measurement in ambient air: elucidation, quantification, and strategies for mitigation of analytical bias.

Science.gov (United States)

Brown, Richard J C; Kumar, Yarshini; Brown, Andrew S; Kim, Ki-Hyun

2011-09-15

The short- and long-term memory effects associated with measurements of mercury vapor in air using gold-coated silica adsorption tubes have been described. Data are presented to quantify these effects and to determine their dependence on certain relevant measurement parameters, such as number of heating cycles used for each analysis, age of adsorption tube, mass of mercury on adsorption tube, and the length of time between analyses. The results suggest that the long-term memory effect is due to absorption of mercury within the bulk gold in the adsorption tube, which may only be fully liberated by allowing enough time for this mercury to diffuse to the gold surface. The implications of these effects for air quality networks making these measurements routinely has been discussed, and recommendations have been made to ensure any measurement bias is minimized.

Functionalized diatom silica microparticles for removal of mercury ions

International Nuclear Information System (INIS)

Yu Yang; Addai-Mensah, Jonas; Losic, Dusan

2012-01-01

Diatom silica microparticles were chemically modified with self-assembled monolayers of 3-mercaptopropyl-trimethoxysilane (MPTMS), 3-aminopropyl-trimethoxysilane (APTES) and n-(2-aminoethyl)-3-aminopropyl-trimethoxysilane (AEAPTMS), and their application for the adsorption of mercury ions (Hg(II)) is demonstrated. Fourier transform infrared spectroscopy and x-ray photoelectron spectroscopy analyses revealed that the functional groups (–SH or –NH 2 ) were successfully grafted onto the diatom silica surface. The kinetics and efficiency of Hg(II) adsorption were markedly improved by the chemical functionalization of diatom microparticles. The relationship among the type of functional groups, pH and adsorption efficiency of mercury ions was established. The Hg(II) adsorption reached equilibrium within 60 min with maximum adsorption capacities of 185.2, 131.7 and 169.5 mg g -1 for particles functionalized with MPTMS, APTES and AEAPTMS, respectively. The adsorption behavior followed a pseudo-second-order reaction model and Langmuirian isotherm. These results show that mercapto- or amino-functionalized diatom microparticles are promising natural, cost-effective and environmentally benign adsorbents suitable for the removal of mercury ions from aqueous solutions.

The adsorption of mercury on tungsten (100) studied by ultra-violet photoelectron spectroscopy

International Nuclear Information System (INIS)

Egelhoff, W.F. Jr.; Perry, D.L.; Linnett, J.W.

1976-01-01

In recent years, photoelectron spectroscopy has been applied to the study of adsorption on several metal surfaces. A popular choice of substrate has been the 100 face of single crystal tungsten, since adsorption on this surface has been well-characterised by a wide variety of experimental techniques. In this letter a study of the adsorption of mercury on W(100) by ultra-violet photoelectron spectroscopy (UPS) is reported. These results, seen in the context of previous UPS studies of chemisorption, show a number of interesting features. (Auth.)

The method of determination of mercury adsorption from flue gases

Directory of Open Access Journals (Sweden)

Budzyń Stanisław

2017-01-01

Full Text Available For several recent years Faculty of Energy and Fuels of the AGH University of Science and Technology in Krakow conduct intensive studies on the occurrence of mercury contained in thermal and coking coals, as well as on the possible reduction of fossil-fuel mercury emissions. This research focuses, among others, on application of sorbents for removal of mercury from flue gases. In this paper we present the methodology for testing mercury adsorption using various types of sorbents, in laboratory conditions. Our model assumes burning a coal sample, with a specific mercury content, in a strictly determined time period and temperature conditions, oxygen or air flow rates, and the flow of flue gases through sorbent in a specific temperature. It was developed for particular projects concerning the possibilities of applying different sorbents to remove mercury from flue gases. Test stand itself is composed of a vertical pipe furnace inside which a quartz tube was mounted for sample burning purposes. At the furnace outlet, there is a heated glass vessel with a sorbent sample through which flue gases are passing. Furnace allows burning at a defined temperature. The exhaust gas flow path is heated to prevent condensation of the mercury vapor prior to contact with a sorbent. The sorbent container is positioned in the heating element, with controlled and stabilized temperature, which allows for testing mercury sorption in various temperatures. Determination of mercury content is determined before (coal and sorbent, as well as after the process (sorbent and ash. The mercury balance is calculated based on the Hg content determination results. This testing method allows to study sorbent efficiency, depending on sorption temperature, sorbent grain size, and flue-gas rates.

Simulation of mercury capture by sorbent injection using a simplified model.

Science.gov (United States)

Zhao, Bingtao; Zhang, Zhongxiao; Jin, Jing; Pan, Wei-Ping

2009-10-30

Mercury pollution by fossil fuel combustion or solid waste incineration is becoming the worldwide environmental concern. As an effective control technology, powdered sorbent injection (PSI) has been successfully used for mercury capture from flue gas with advantages of low cost and easy operation. In order to predict the mercury capture efficiency for PSI more conveniently, a simplified model, which is based on the theory of mass transfer, isothermal adsorption and mass balance, is developed in this paper. The comparisons between theoretical results of this model and experimental results by Meserole et al. [F.B. Meserole, R. Chang, T.R. Carrey, J. Machac, C.F.J. Richardson, Modeling mercury removal by sorbent injection, J. Air Waste Manage. Assoc. 49 (1999) 694-704] demonstrate that the simplified model is able to provide good predictive accuracy. Moreover, the effects of key parameters including the mass transfer coefficient, sorbent concentration, sorbent physical property and sorbent adsorption capacity on mercury adsorption efficiency are compared and evaluated. Finally, the sensitive analysis of impact factor indicates that the injected sorbent concentration plays most important role for mercury capture efficiency.

Determination of mercury in air by adsorption on Hopcalite and by neutron activation analysis

International Nuclear Information System (INIS)

Leyni-Barbaz, D.; Zikovsky, L.; Poissant, L.

2002-01-01

A new method for the determination of mercury in air has been developed. It combines the adsorption of mercury on Hopcalite (a material approved for this purpose by the National Institute of Health of the United States) and its quantification by neutron activation. The concentrations of mercury in office air in Montreal, Canada, were determined by instrumental semiabsolute neutron activation analysis. They varied from 39 to 48 ng/m 3 . The results were compared with the concentrations of mercury in office air determined simultaneously at the same place by cold vapour atomic fluorescence spectrophotometry. A close correlation between the results of the 2 methods was obtained. The detection limit of our method is about 14 ng/m 3 . (author)

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

Science.gov (United States)

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

Theoretical evaluation on selective adsorption characteristics of alkali metal-based sorbents for gaseous oxidized mercury.

Science.gov (United States)

Tang, Hongjian; Duan, Yufeng; Zhu, Chun; Cai, Tianyi; Li, Chunfeng; Cai, Liang

2017-10-01

Alkali metal-based sorbents are potential for oxidized mercury (Hg 2+ ) selective adsorption but show hardly effect to elemental mercury (Hg 0 ) in flue gas. Density functional theory (DFT) was employed to investigate the Hg 0 and HgCl 2 adsorption mechanism over alkali metal-based sorbents, including calcium oxide (CaO), magnesium oxide (MgO), potassium chloride (KCl) and sodium chloride (NaCl). Hg 0 was found to weakly interact with CaO (001), MgO (001), KCl (001) and NaCl (001) surfaces while HgCl 2 was effectively adsorbed on top-O and top-Cl sites. Charge transfer and bond population were calculated to discuss the covalency and ionicity of HgCl 2 bonding with the adsorption sites. The partial density of states (PDOS) analysis manifests that HgCl 2 strongly interacts with surface sites through the orbital hybridizations between Hg and top O or Cl. Frontier molecular orbital (FMO) energy and Mulliken electronegativity are introduced as the quantitative criteria to evaluate the reactivity of mercury species and alkali metal-based sorbents. HgCl 2 is identified as a Lewis acid and more reactive than Hg 0 . The Lewis basicity of the four alkali metal-based sorbents is predicted as the increasing order: NaCl < MgO < KCl < CaO, in consistence with the trend of HgCl 2 adsorption energies. Copyright © 2017 Elsevier Ltd. All rights reserved.

Enhanced capture of elemental mercury by bamboo-based sorbents

International Nuclear Information System (INIS)

Tan, Zengqiang; Xiang, Jun; Su, Sheng; Zeng, Hancai; Zhou, Changsong; Sun, Lushi; Hu, Song; Qiu, Jianrong

2012-01-01

Highlights: ► The KI-modified BC has excellent capacity for elemental mercury removal. ► The chemisorption plays a dominant role for the modified BC materials. ► The BC-I has strong anti-poisoning ability with the presence of NO or SO 2 . - Abstract: To develop cost-effective sorbent for gas-phase elemental mercury removal, the bamboo charcoal (BC) produced from renewable bamboo and KI modified BC (BC-I) were used for elemental mercury removal. The effect of NO, SO 2 on gas-phase Hg 0 adsorption by KI modified BC was evaluated on a fixed bed reactor using an online mercury analyzer. BET surface area analysis, temperature programmed desorption (TPD) and X-ray photoelectron spectroscopy (XPS) were used to determine the pore structure and surface chemistry of the sorbents. The results show that KI impregnation reduced the sorbents’ BET surface area and total pore volume compared with that of the original BC. But the BC-I has excellent adsorption capacity for elemental mercury at a relatively higher temperature of 140 °C and 180 °C. The presence of NO or SO 2 could inhibit Hg 0 capture, but BC-I has strong anti-poisoning ability. The specific reaction mechanism has been further analyzed.

Evaluation of the potassium adsorption capacity of a potassium adsorption filter during rapid blood transfusion.

Science.gov (United States)

Matsuura, H; Akatsuka, Y; Muramatsu, C; Isogai, S; Sugiura, Y; Arakawa, S; Murayama, M; Kurahashi, M; Takasuga, H; Oshige, T; Yuba, T; Mizuta, S; Emi, N

2015-05-01

The concentration of extracellular potassium in red blood cell concentrates (RCCs) increases during storage, leading to risk of hyperkalemia. A potassium adsorption filter (PAF) can eliminate the potassium at normal blood transfusion. This study aimed to investigate the potassium adsorption capacity of a PAF during rapid blood transfusion. We tested several different potassium concentrations under a rapid transfusion condition using a pressure bag. The adsorption rates of the 70-mEq/l model were 76·8%. The PAF showed good potassium adsorption capacity, suggesting that this filter may provide a convenient method to prevent hyperkalemia during rapid blood transfusion. © 2015 International Society of Blood Transfusion.

Effective removal of hexavalent mercury from aqueous solution by modified polymeric nanoadsorbent

Directory of Open Access Journals (Sweden)

Lida Rahmanzadeh

2016-07-01

Full Text Available Mercury is one of the most toxic metals present in the environment. Adsorption has been proposed among the technologies for mercury adsorbent. The kinetics of adsorption depends on the adsorbent concentration, and the physical and chemical characteristics of adsorbent. In this study we were used a novel adsorbent, magnetite-polyrhodanine core- shell nanoparticles, for removing Hg(II from aqueous solution. The effect of pH, initial Hg(II concentration, initial adsorbent concentration and contact time on the efficiency of Hg(II removal were investigated systematically by batch experiments. The maximum adsorption capacity was obtained 29.14 mg g-1 at PH=6.5 and 25°C with 10 g L-1 nano adsorbent. The kinetic data of adsorption of Hg(II ion on the synthesized adsorbent were best described by a pseudo- second- order equation, indicating their chemical adsorption. The Freundlich, Langmuir and Temkin isotherms were used to modeling of mercury adsorption on Hg(II in aqueous medium which modeled best by the Freundlich isotherm is whole concentration rage.

Sulfide treatment to inhibit mercury adsorption onto activated carbon in carbon-in-pulp gold recovery circuits

Energy Technology Data Exchange (ETDEWEB)

Touro, F.J.; Lipps, D.A.

1988-03-29

A process for treating a mercury-contaminated, precious metal-containing ore slurry is described comprising: (a) reacting sulfide anions in an aqueous ore slurry of a mercury and precious metal-containing carbonaceous ore, and (b) conducting a simultaneous cyanide leach and carbon-in-pulp adsorption of the precious metal from the carbonaceous ore in the sulfide-containing ore slurry.

Adsorption study of mercury on lignite in the presence of different anions

Directory of Open Access Journals (Sweden)

Irma Robles

2016-05-01

Full Text Available This study compares the effect of different anions such as chloride, nitrate, and sulphate on the mercury adsorption onto lignite, which was a model material for the humus-containing organics in soil, and can be considered as a natural sorbent in the remediation of contaminated sites. Since the complex formation can significantly influence the mercury sorption, besides chloride, the effects of other complex-forming agents such as ethylenediaminetetraacetic acid, and thiocyanate were also tested. Various batch type and dynamic experiments were performed and four sorption models (Langmuir, Freundlich, Temkin and Dubinin-Radushkevich were used to evaluate the sorption data.

Adsorption of multi-heavy metals Zn and Cu onto surficial sediments: modeling and adsorption capacity analysis.

Science.gov (United States)

Li, Shanshan; Zhang, Chen; Wang, Meng; Li, Yu

2014-01-01

Improved multiple regression adsorption models (IMRAMs) was developed to estimate the adsorption capacity of the components [Fe oxides (Fe), Mn oxides (Mn), organic materials (OMs), residuals] in surficial sediments for multi-heavy metal Zn and Cu. IMRAM is an improved version over MRAM, which introduces a computer program in the model developing process. As MRAM, Zn(Cu) IMRAM, and Cu(Zn) IMRAM again confirmed that there is significant interaction effects that control the adsorption of compounded Zn and Cu, which was neglected by additional adsorption model. The verification experiment shows that the relative deviation of the IMRAMs is less than 13%. It is revealed by the IMRAMs that Mn, which has the greatest adsorption capability for compounded Zn and Cu (54.889 and 161.180 mg/l, respectively), follows by interference adsorption capacity of Fe/Mn (-1.072 and -24.591 mg/l respectively). Zn and Cu influence each other through different mechanisms. When Zn is the adsorbate, compounded Cu mainly affects the adsorption capacities of Fe/Mn and Fe/Mn/OMs; while when Cu is the adsorbate, compounded Zn mainly exerts its effect on Mn, Fe/Mn, and Mn/OMs. It also shows that the compounded Zn or Cu weakened the interference adsorption of Fe/Mn, and meanwhile, strengthened the interference adsorption of Mn/OMs.

Evaluation of adsorption capacity of acetaminophen on activated ...

African Journals Online (AJOL)

Purpose: To investigate varying dosage forms of activated charcoal obtained from community pharmacy outlets in Nigeria for their adsorption capacity when challenged with acetaminophen. Methods: Equilibruim kinetics of acetaminophen adsorption onto activated charcoal surface was determined via batch studies at ...

Adsorption characteristics of Copper (Ⅱ), Zinc (Ⅱ) and Mercury (Ⅱ) by four kinds of immobilized fungi residues.

Science.gov (United States)

Li, Xia; Zhang, Dan; Sheng, Fei; Qing, Hui

2018-01-01

This study investigated the adsorption characteristics of Copper (Ⅱ), Zinc (Ⅱ) and Mercury (Ⅱ) by immobilized Flammulina velutipes, Auricularia polytricha, Pleurotus eryngii and Pleurotus ostreatus residues. Lagergren model, elovich and intraparticle diffusion model were used to present the adsorption kinetics, and it was proved that Langmuir isotherm model and pseudo-second order kinetics are the best suitable model with high correlation coefficient to characterize the adsorption process of Copper (Ⅱ), Zinc (Ⅱ) and Mercury (Ⅱ). The results showed that adsorption process finished in 120min at pH 6.0. The adsorption rate of Cu 2+ , Zn 2+ and Hg 2+ were reached to 53.8-84.1% of total in the initial 60min, and finished in 120min. Ion exchange and complexation of F. velutipes were the main mechanisms for adsorption of metal ions by characterizations of Scanning electron microscopy (SEM) and Fourier transform infrared (FTIR). In addition the functional group of cell walls such as hydroxyl, amide, carbonyl, phosphoric played a critical role in ions adsorption of edible mushroom residues. Cu 2+ , Zn 2+ and Hg 2+ in wastewater could be efficiently removed by F. velutipes residue with removal ratio of 73.11%, 66.67% and 69.35%, respectively. Copyright © 2017 Elsevier Inc. All rights reserved.

Determination of mercury in discharge water from plastic manufactory by neutron activation analysis and copper powder adsorption

Energy Technology Data Exchange (ETDEWEB)

Houng-Huei, L [National Tsing Hua University Hsinchu, Taiwan (Republic of China)

1979-02-28

Through copper powder adsorption, neutron activation analysis was used to determine the mercury in discharge water from a plastic manufactory where the water samples were taken from various discharge ditches. The experimental results showed that waste water from mercury cells contained 1.7x10/sup -9/ approximately 8.19x10/sup -6/ g Hg/ml while water samples taken from other areas did not show significant mercury level and were below the limit of detection.

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

Science.gov (United States)

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

1998-01-01

Coal-derived activated carbons (CDACs) were tested for their suitability in removing trace amounts of vapor-phase mercury from simulated flue gases generated by coal combustion. CDACs were prepared in bench-scale and pilot-scale fluidized-bed reactors with a three-step process, including coal preoxidation, carbonization, and then steam activation. CDACs from high-organicsulfur Illinois coals had a greater equilibrium Hg0 adsorption capacity than activated carbons prepared from a low-organic-sulfur Illinois coal. When a low-organic-sulfur CDAC was impregnated with elemental sulfur at 600 ??C, its equilibrium Hg0 adsorption capacity was comparable to the adsorption capacity of the activated carbon prepared from the high-organicsulfur coal. X-ray diffraction and sulfur K-edge X-ray absorption near-edge structure examinations showed that the sulfur in the CDACs was mainly in organic forms. These results suggested that a portion of the inherent organic sulfur in the starting coal, which remained in the CDACs, played an important role in adsorption of Hg0. Besides organic sulfur, the BET surface area and micropore area of the CDACs also influenced Hg0 adsorption capacity. The HgCl2 adsorption capacity was not as dependent on the surface area and concentration of sulfur in the CDACs as was adsorption of Hg0. The properties and mercury adsorption capacities of the CDACs were compared with those obtained for commercial Darco FGD carbon.

Enhanced capture of elemental mercury by bamboo-based sorbents

Energy Technology Data Exchange (ETDEWEB)

Tan, Zengqiang [State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China); Xiang, Jun, E-mail: xiangjun@mail.hust.edu.cn [State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China); Su, Sheng, E-mail: susheng_sklcc@hotmail.com [State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China); Zeng, Hancai; Zhou, Changsong; Sun, Lushi; Hu, Song; Qiu, Jianrong [State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China)

2012-11-15

Highlights: Black-Right-Pointing-Pointer The KI-modified BC has excellent capacity for elemental mercury removal. Black-Right-Pointing-Pointer The chemisorption plays a dominant role for the modified BC materials. Black-Right-Pointing-Pointer The BC-I has strong anti-poisoning ability with the presence of NO or SO{sub 2}. - Abstract: To develop cost-effective sorbent for gas-phase elemental mercury removal, the bamboo charcoal (BC) produced from renewable bamboo and KI modified BC (BC-I) were used for elemental mercury removal. The effect of NO, SO{sub 2} on gas-phase Hg{sup 0} adsorption by KI modified BC was evaluated on a fixed bed reactor using an online mercury analyzer. BET surface area analysis, temperature programmed desorption (TPD) and X-ray photoelectron spectroscopy (XPS) were used to determine the pore structure and surface chemistry of the sorbents. The results show that KI impregnation reduced the sorbents' BET surface area and total pore volume compared with that of the original BC. But the BC-I has excellent adsorption capacity for elemental mercury at a relatively higher temperature of 140 Degree-Sign C and 180 Degree-Sign C. The presence of NO or SO{sub 2} could inhibit Hg{sup 0} capture, but BC-I has strong anti-poisoning ability. The specific reaction mechanism has been further analyzed.

Effect of the impregnation of carbon cloth with ethylenediaminetetraacetic acid on its adsorption capacity for the adsorption of several metal ions

International Nuclear Information System (INIS)

Afkhami, Abbas; Madrakian, Tayyebeh; Amini, Azadeh; Karimi, Ziba

2008-01-01

Effect of loading of C-cloth with ethylenediaminetetraacetic acid (EDTA) on the adsorption capacity for the adsorption of several metal cations was studied. The concentration of ions in the solution was monitored using atomic absorption spectrometry. The adsorption isotherm data for the cations were derived at 25 deg. C and treated according to Langmuir and Freundlich models and was found that for most of the investigated cations Langmuir model was more successful. Adsorption capacities determined from Langmuir isotherms. Loading of the adsorbent with EDTA increased the adsorption capacity for the adsorption of all of the investigation ions

Analysis of mercury adsorption at the gibbsite-water interface using the CD-MUSIC model.

Science.gov (United States)

Park, Chang Min

2018-05-22

Mercury (Hg), one of the most toxic substances in nature, has long been released during the anthropogenic activity. A correct description of the adsorptive behavior of mercury is important to gain a better insight into its fate and transport in natural mineral surfaces, which will be a prerequisite for the development of surface complexation model for the adsorption processes. In the present study, simulation experiments on macroscopic Hg(II) sorption by gibbsite (α-Al(OH) 3 ), a representative aluminum (hydr)oxide mineral, were performed using the charge distribution and multi-site complexation (CD-MUSIC) approach with 1-pK triple plane model (TPM). For this purpose, several data sets which had already been reported in the literature were employed to analyze the effect of pH, ionic strength, and co-exisiting ions (NO 3 - and Cl - ) on the Hg(II) adsorption onto gibbsite. Sequential optimization approach was used to determine the acidity and asymmetric binding constants for electrolyte ions and the affinity constants of the surface species through the model simulation using FITEQLC (a modified code of FITEQL 4.0). The model successfully incorporated the presence of inorganic ligands at the dominant edge (100) face of gibbsite with consistent surface species, which was evidenced by molecular scale analysis. The model was verified with an independent set of Hg(II) adsorption data incorporating carbonate binding species in an open gibbsite-water system.

[Evaluation of the mercury accumulating capacity of pepper (Capsicum annuum)].

Science.gov (United States)

Pérez-Vargas, Híver M; Vidal-Durango, Jhon V; Marrugo-Negrete, José L

2014-01-01

To assess the mercury accumulating capacity in contaminated soils from the community of Mina Santa Cruz, in the south of the department of Bolívar, Colombia, of the pepper plant (Capsicum annuum), in order to establish the risk to the health of the consuming population. Samples were taken from tissues (roots, stems, and leaves) of pepper plants grown in two soils contaminated with mercury and a control soil during the first five months of growth to determine total mercury through cold vapor atomic absorption spectrometry. Total mercury was determined in the samples of pepper plant fruits consumed in Mina Santa Cruz. The mean concentrations of total mercury in the roots were higher than in stems and leaves. Accumulation in tissues was influenced by mercury levels in soil and the growth time of the plants. Mercury concentrations in fruits of pepper plant were lower than tolerable weekly intake provided by WHO. Percent of translocation of mercury to aerial parts of the plant were low in both control and contaminated soils. Despite low levels of mercury in this food, it is necessary to minimize the consumption of food contaminated with this metal.

Dynamic measurement of mercury adsorption and oxidation on activated carbon in simulated cement kiln flue gas

DEFF Research Database (Denmark)

Zheng, Yuanjing; Jensen, Anker Degn; Windelin, Christian

2012-01-01

of the sulfite converter is short and typically within 2min. Dynamic mercury adsorption and oxidation tests on commercial activated carbons Darco Hg and HOK standard were performed at 150°C using simulated cement kiln gas and a fixed bed reactor system. It is shown that the converter and analyzer system...... are still under development and are investigated in this work. A commercial red brass converter was tested at 180°C and it was found that the red brass chips work in nitrogen atmosphere only, but do not work properly under simulated cement kiln flue gas conditions. Test of the red brass converter using only...... elemental mercury shows that when HCl is present with either SO2 or NOx the mercury measurement after the converter is unstable and lower than the elemental mercury inlet level. The conclusion is that red brass chips cannot fully reduce oxidized mercury to elemental mercury when simulated cement kiln gas...

Introduction of Molecular Building Blocks to Improve the Stability of Metal-Organic Frameworks for Efficient Mercury Removal.

Science.gov (United States)

Jiang, Shu-Yi; He, Wen-Wen; Li, Shun-Li; Su, Zhong-Min; Lan, Ya-Qian

2018-05-08

With expanding human needs, many heavy metals were mined, smelted, processed, and manufactured for commercialization, which caused serious environmental pollutions. Currently, many adsorption materials are applied in the field of adsorption of heavy metals. Among them, the principle of many mercury adsorbents is based on the interaction between mercury and sulfur. Here, a S-containing metal-organic framework NENU-400 was synthesized for effective mercury extraction. Unfortunately, the skeleton of NENU-400 collapsed easily when exposed to the mercury liquid solution. To improve the stability, a synthetic strategy installing molecular building blocks (MBBs) into the channels was used. Modified by the MBBs, a more stable nanoporous framework was synthesized, which not only exhibits a high capacity of saturation mercury uptake but also shows high selectivity and efficient recyclability.

High capacity adsorption media and method of producing

Science.gov (United States)

Tranter, Troy J.; Mann, Nicholas R.; Todd, Terry A.; Herbst, Ronald S.

2010-10-05

A method of producing an adsorption medium to remove at least one constituent from a feed stream. The method comprises dissolving and/or suspending at least one metal compound in a solvent to form a metal solution, dissolving polyacrylonitrile into the metal solution to form a PAN-metal solution, and depositing the PAN-metal solution into a quenching bath to produce the adsorption medium. The at least one constituent, such as arsenic, selenium, or antimony, is removed from the feed stream by passing the feed stream through the adsorption medium. An adsorption medium having an increased metal loading and increased capacity for arresting the at least one constituent to be removed is also disclosed. The adsorption medium includes a polyacrylonitrile matrix and at least one metal hydroxide incorporated into the polyacrylonitrile matrix.

Mercury capture within coal-fired power plant electrostatic precipitators: model evaluation.

Science.gov (United States)

Clack, Herek L

2009-03-01

Efforts to reduce anthropogenic mercury emissions worldwide have recently focused on a variety of sources, including mercury emitted during coal combustion. Toward that end, much research has been ongoing seeking to develop new processes for reducing coal combustion mercury emissions. Among air pollution control processes that can be applied to coal-fired boilers, electrostatic precipitators (ESPs) are by far the most common, both on a global scale and among the principal countries of India, China, and the U.S. that burn coal for electric power generation. A previously reported theoretical model of in-flight mercury capture within ESPs is herein evaluated against data from a number of full-scale tests of activated carbon injection for mercury emissions control. By using the established particle size distribution of the activated carbon and actual or estimated values of its equilibrium mercury adsorption capacity, the incremental reduction in mercury concentration across each ESP can be predicted and compared to experimental results. Because the model does not incorporate kinetics associated with gas-phase mercury transformation or surface adsorption, the model predictions representthe mass-transfer-limited performance. Comparing field data to model results reveals many facilities performing at or near the predicted mass-transfer-limited maximum, particularly at low rates of sorbent injection. Where agreement is poor between field data and model predictions, additional chemical or physical phenomena may be responsible for reducing mercury removal efficiencies.

A facile method to prepare dual-functional membrane for efficient oil removal and in situ reversible mercury ions adsorption from wastewater

Science.gov (United States)

Zhang, Qingdong; Liu, Na; Cao, Yingze; Zhang, Weifeng; Wei, Yen; Feng, Lin; Jiang, Lei

2018-03-01

In this work, a novel thiol covered polyamide (nylon 66) microfiltration membrane was fabricated by combining mussel-inspired chemistry and coupling reaction, which owns excellent dual-function that can simultaneously remove oil from water efficiently and adsorb the mercury ions contained in the wastewater reversibly. Such membrane exhibited high oil/water separation efficiency, outstanding mercury adsorption ability, and good stability. Moreover, it can be regenerated in nitric acid solution, and maintain its good adsorption performance. The as-prepared membrane showed great potentials for water purification to reduce the heavy metal ion pollution and complicated industrial oily wastewater and living wastewater.

CoFe2O4@MIL-100(Fe) hybrid magnetic nanoparticles exhibit fast and selective adsorption of arsenic with high adsorption capacity

Science.gov (United States)

Yang, Ji-Chun; Yin, Xue-Bo

2017-01-01

In this study, we report the synthesis and application of mesoporous CoFe2O4@MIL-100(Fe) hybrid magnetic nanoparticles (MNPs) for the simultaneous removal of inorganic arsenic (iAs). The hybrid adsorbent had a core-shell and mesoporous structure with an average diameter of 260 nm. The nanoscale size and mesoporous character impart a fast adsorption rate and high adsorption capacity for iAs. In total, 0.1 mg L−1 As(V) and As(III) could be adsorbed within 2 min, and the maximum adsorption capacities were 114.8 mg g−1 for As(V) and 143.6 mg g−1 for As(III), higher than most previously reported adsorbents. The anti-interference capacity for iAs adsorption was improved by the electrostatic repulsion and size exclusion effects of the MIL-100(Fe) shell, which also decreased the zero-charge point of the hybrid absorbent for a broad pH adsorption range. The adsorption mechanisms of iAs on the MNPs are proposed. An Fe-O-As structure was formed on CoFe2O4@MIL-100(Fe) through hydroxyl substitution with the deprotonated iAs species. Monolayer adsorption of As(V) was observed, while hydrogen bonding led to the multi-layer adsorption of neutral As(III) for its high adsorption capacity. The high efficiency and the excellent pH- and interference-tolerance capacities of CoFe2O4@MIL-100(Fe) allowed effective iAs removal from natural water samples, as validated with batch magnetic separation mode and a portable filtration strategy. PMID:28102334

Capability of defective graphene-supported Pd{sub 13} and Ag{sub 13} particles for mercury adsorption

Energy Technology Data Exchange (ETDEWEB)

Meeprasert, Jittima; Junkaew, Anchalee; Rungnim, Chompoonut; Kunaseth, Manaschai [National Nanotechnology Center, NSTDA, 111 Thailand Science Park, Klong Luang, Pathum Thani 12120 Thailand (Thailand); Kungwan, Nawee [Department of Chemistry, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Promarak, Vinich [School of Molecular Science and Engineering, Vidyasirimedhi Institute of Science and Technology, Wangchan, Rayong 21210 (Thailand); Namuangruk, Supawadee, E-mail: supawadee@nanotec.or.th [National Nanotechnology Center, NSTDA, 111 Thailand Science Park, Klong Luang, Pathum Thani 12120 Thailand (Thailand)

2016-02-28

Graphical abstract: Defective graphene (DG) supported Ag{sub 13} and Pd{sub 13} nanoparticles acts as sorbents for elementary mercury (Hg{sup 0}) adsorption. Hg is inert to DG surface, but it moderately adsorbs on deposited Ag{sub 13}-DG and strongly adsorbs on deposited Pd{sub 13}-DG. - Highlights: • Pd{sub 13}-DG composite has highest stability. • Pd{sub 13}-DG composite is the most reactive sorbent for Hg{sup 0} adsorption. • Hg{sup 0} adsorption abilities of Pd-DG composites are relatively higher than those of Ag-DG composites. • The d-band center of deposited metal is an adsorption descriptor of composite models. - Abstract: Reactivity of single-vacancy defective graphene (DG) and DG-supported Pd{sub n} and Ag{sub n} (n = 1, 13) for mercury (Hg{sup 0}) adsorption has been studied using density functional theory calculation. The results show that Pd{sub n} binds defective site of DG much stronger than the Ag{sub n}, while metal nanocluster binds DG stronger than single metal atom. Metal clustering affects the adsorption ability of Pd composite while that of Ag is comparatively less. The binding strength of −8.49 eV was found for Pd{sub 13} binding on DG surface, indicating its high stability. Analyses of structure, energy, partial density of states, and d-band center (ε{sub d}) revealed that the adsorbed metal atom or cluster enhances the reactivity of DG toward Hg adsorption. In addition, the Hg adsorption ability of M{sub n}-DG composite is found to be related to the ε{sub d} of the deposited M{sub n}, in which the closer ε{sub d} of M{sub n} to the Fermi level correspond to the higher adsorption strength of Hg on M{sub n}-DG composite. The order of Hg adsorption strength on M{sub n}-DG composite are as follows: Pd{sub 13} (−1.68 eV) >> Ag{sub 13} (−0.67 eV) ∼ Ag{sub 1} (−0.69 eV) > Pd{sub 1} (−0.62 eV). Pd{sub 13}-DG composite is therefore more efficient sorbent for Hg{sup 0} removal in terms of high stability and high adsorption

Method and apparatus for sampling atmospheric mercury

Science.gov (United States)

Trujillo, Patricio E.; Campbell, Evan E.; Eutsler, Bernard C.

1976-01-20

A method of simultaneously sampling particulate mercury, organic mercurial vapors, and metallic mercury vapor in the working and occupational environment and determining the amount of mercury derived from each such source in the sampled air. A known volume of air is passed through a sampling tube containing a filter for particulate mercury collection, a first adsorber for the selective adsorption of organic mercurial vapors, and a second adsorber for the adsorption of metallic mercury vapor. Carbon black molecular sieves are particularly useful as the selective adsorber for organic mercurial vapors. The amount of mercury adsorbed or collected in each section of the sampling tube is readily quantitatively determined by flameless atomic absorption spectrophotometry.

Optimization of CO2 adsorption capacity and cyclical adsorption/desorption on tetraethylenepentamine-supported surface-modified hydrotalcite.

Science.gov (United States)

Thouchprasitchai, Nutthavich; Pintuyothin, Nuthapol; Pongstabodee, Sangobtip

2018-03-01

The objective of this research was to investigate CO 2 adsorption capacity of tetraethylenepentamine-functionalized basic-modified calcined hydrotalcite (TEPA/b-cHT) sorbents at atmospheric pressure formed under varying TEPA loading levels, temperatures, sorbent weight to total gaseous flow rate (W/F) ratios and CO 2 concentrations in the influent gas. The TEPA/b-cHT sorbents were characterized by means of X-ray diffraction (XRD), Fourier transform infrared spectrometry (FT-IR), thermal gravimetric analysis (TGA), Brunauer-Emmet-Teller (BET) analysis of nitrogen (N 2 ) adsorption/desorption and carbon-hydrogen-nitrogen (CHN) elemental analysis. Moreover, a full 2 4 factorial design with three central points at a 95% confidence interval was used to screen important factor(s) on the CO 2 adsorption capacity. It revealed that 85.0% variation in the capacity came from the influence of four main factors and the 15.0% one was from their interactions. A face-centered central composite design response surface method (FCCCD-RSM) was then employed to optimize the condition, the maximal capacity of 5.5-6.1mmol/g was achieved when operating with a TEPA loading level of 39%-49% (W/W), temperature of 76-90°C, W/F ratio of 1.7-2.60(g·sec)/cm 3 and CO 2 concentration of 27%-41% (V/V). The model fitted sufficiently the experimental data with an error range of ±1.5%. From cyclical adsorption/desorption and selectivity at the optimal condition, the 40%TEPA/b-cHT still expressed its effective performance after eight cycles. Copyright © 2017. Published by Elsevier B.V.

Inhibition and promotion of trace pollutant adsorption within electrostatic precipitators.

Science.gov (United States)

Clack, Herek L

2017-08-01

Among the technologies available for reducing mercury emissions from coal-fired electric utilities is the injection of a powdered sorbent, often some form of activated carbon, into the flue gas upstream of the particulate control device, most commonly an electrostatic precipitator (ESP). Detailed measurements of mercury removal within ESPs are lacking due to the hazardous environment they pose, increasing the importance of analysis and numerical simulation in understanding the mechanisms involved. Our previous analyses revealed that mercury adsorption by particles suspended in the gas and mercury adsorption by particles collected on internal ESP surfaces are not additive removal mechanisms but rather are competitive. The present study expands on this counterintuitive finding. Presented are results from numerical simulations reflecting the complete range of possible mass transfer boundary conditions representing mercury adsorption by the accumulated dust cake covering internal ESP collection electrodes. Using the two mercury removal mechanisms operating concurrently and interdependently always underperforms the sum of the two mechanisms' individual contributions. The dual use of electrostatic precipitators (ESPs) for particulate removal and adsorption of trace gaseous pollutants such as mercury is increasing as mercury regulations become more widespread. Under such circumstances, mercury adsorption by particles suspended in the gas and mercury adsorption by particles collected on internal ESP surfaces are competitive. Together, the two mercury removal mechanisms always underperform the sum of their two independent contributions. These findings can inform strategies sought by electric utilities for reducing the usage costs of mercury sorbents.

Removal of mercury from aqueous solutions using activated carbon prepared from agricultural by-product/waste.

Science.gov (United States)

Rao, M Madhava; Reddy, D H K Kumar; Venkateswarlu, Padala; Seshaiah, K

2009-01-01

Removal of mercury from aqueous solutions using activated carbon prepared from Ceiba pentandra hulls, Phaseolus aureus hulls and Cicer arietinum waste was investigated. The influence of various parameters such as effect of pH, contact time, initial metal ion concentration and adsorbent dose for the removal of mercury was studied using a batch process. The experiments demonstrated that the adsorption process corresponds to the pseudo-second-order-kinetic models and the equilibrium adsorption data fit the Freundlich isotherm model well. The prepared adsorbents ACCPH, ACPAH and ACCAW had removal capacities of 25.88 mg/g, 23.66 mg/g and 22.88 mg/g, respectively, at an initial Hg(II) concentration of 40 mg/L. The order of Hg(II) removal capacities of these three adsorbents was ACCPH>ACPAH>ACCAW. The adsorption behavior of the activated carbon is explained on the basis of its chemical nature. The feasibility of regeneration of spent activated carbon adsorbents for recovery of Hg(II) and reuse of the adsorbent was determined using HCl solution.

Development of Nano-Sulfide Sorbent for Efficient Removal of Elemental Mercury from Coal Combustion Fuel Gas.

Science.gov (United States)

Li, Hailong; Zhu, Lei; Wang, Jun; Li, Liqing; Shih, Kaimin

2016-09-06

The surface area of zinc sulfide (ZnS) was successfully enlarged using nanostructure particles synthesized by a liquid-phase precipitation method. The ZnS with the highest surface area (named Nano-ZnS) of 196.1 m(2)·g(-1) was then used to remove gas-phase elemental mercury (Hg(0)) from simulated coal combustion fuel gas at relatively high temperatures (140 to 260 °C). The Nano-ZnS exhibited far greater Hg(0) adsorption capacity than the conventional bulk ZnS sorbent due to the abundance of surface sulfur sites, which have a high binding affinity for Hg(0). Hg(0) was first physically adsorbed on the sorbent surface and then reacted with the adjacent surface sulfur to form the most stable mercury compound, HgS, which was confirmed by X-ray photoelectron spectroscopy analysis and a temperature-programmed desorption test. At the optimal temperature of 180 °C, the equilibrium Hg(0) adsorption capacity of the Nano-ZnS (inlet Hg(0) concentration of 65.0 μg·m(-3)) was greater than 497.84 μg·g(-1). Compared with several commercial activated carbons used exclusively for gas-phase mercury removal, the Nano-ZnS was superior in both Hg(0) adsorption capacity and adsorption rate. With this excellent Hg(0) removal performance, noncarbon Nano-ZnS may prove to be an advantageous alternative to activated carbon for Hg(0) removal in power plants equipped with particulate matter control devices, while also offering a means of reusing fly ash as a valuable resource, for example as a concrete additive.

Adsorption of 2,4,6-trinitrotoluene on carboxylated porous polystyrene microspheres

International Nuclear Information System (INIS)

Ye Zhengfang; Meng Qingqiang; Lu Shengtao

2012-01-01

Large-pore-size (150 nm) polystyrene (PSt) microspheres were carboxylated with phthalic anhydride (PA) through Friedel-Crafts acetylation to study the adsorption of 2,4,6-trinitrotoluene (TNT) on this material from aqueous solution. The scanning electron microscope (SEM) images and mercury porosimetry measurements (MPM) of the microspheres showed that the pore structure was unchanged during the reaction. High adsorption capacity (11.2 mg g -1 of suction-dried adsorbent) and adsorption rate (33.9 mg g -1 h -1 ) for TNT were observed during the study. As shown by the adsorption isotherm, the adsorption of TNT on PA-PSt can be described by the Freundlich adsorption equation, indicating heterogeneous adsorption process. On-column adsorption of TNT on PA-PSt and elution indicated that TNT can be completely removed from aqueous solution and condensed into acetone.

Ion-imprinted polymethacrylic microbeads as new sorbent for preconcentration and speciation of mercury.

Science.gov (United States)

Dakova, Ivanka; Karadjova, Irina; Georgieva, Ventsislava; Georgiev, George

2009-04-30

Metal ion-imprinted polymer particles have been prepared by copolymerization of methacrylic acid as monomer, trimethylolpropane trimethacrylate as cross-linking agent and 2,2'-azobisisobutyronitrile as initiator, in the presence of Hg(II)-1-(2-thiazolylazo)-2-naphthol complex. The separation and preconcentration characteristics of the Hg-ion-imprinted microbeads for inorganic mercury have been investigated by batch procedure. The optimal pH value for the quantitative sorption is 7. The adsorbed inorganic mercury is easily eluted by 2 mL 4M HNO(3). The adsorption capacity of the newly synthesized Hg ion-imprinted microbeads is 32.0 micromol g(-1) for dry copolymer. The selectivity of the copolymer toward inorganic mercury (Hg(II)) ion is confirmed through the comparison of the competitive adsorptions of Cd(II), Co(II), Cu(II), Ni(II), Pb(II), Zn(II)) and high values of the selectivity and distribution coefficients have been calculated. Experiments performed for selective determination of inorganic mercury in mineral and sea waters showed that the interfering matrix does not influence the extraction efficiency of Hg ion-imprinted microbeads. The detection limit for inorganic mercury is 0.006 microg L(-1) (3 sigma), determined by cold vapor atomic adsorption spectrometry. The relative standard deviation varied in the range 5-9 % at 0.02-1 microg L(-1) Hg levels. The new Hg-ion-imprinted microbeads have been tested and applied for the speciation of Hg in river and mineral waters: inorganic mercury has been determined selectively in nondigested sample, while total mercury e.g. sum of inorganic and methylmercury, has been determined in digested sample.

Mercury removal from coal combustion flue gas by fly ash

Energy Technology Data Exchange (ETDEWEB)

Kuang, Junyan [Chinese Academy of Sciences, Beijing (China). Research Center for Process Pollution Control; Chinese Academy of Sciences, Beijing (China). Graduate Univ.; Xu, Wenqing; Zhu, Tingyu; Jing, Pengfei [Chinese Academy of Sciences, Beijing (China). Research Center for Process Pollution Control

2013-07-01

The effect of physicochemical properties on the mercury adsorption performance of three fly ash samples has been investigated. The samples were tested for mercury adsorption using a fixed-bed with a simulated gas. X-ray fluorescence spectroscopy, X-ray photoelectron spectroscopy and other methods were used to characterize the samples. The results indicate that mercury adsorption on fly ash is mainly physisorption and chemisorption. Uncompleted burned carbon is an important factor for the improvement of mercury removal efficiency, especially, the C-M bond may improve the oxidation of mercury, which formed via the reaction of C and Ti, Si and other elements. The higher specific surface areas and smaller pore diameter are all beneficial for the high mercury removal efficiency. The presence of O{sub 2} plays a positive role on Hg adsorption of modified fly ash, while SO{sub 2} has double role of inhibition because of competitive adsorption and promotion to chemisorption. In addition, sample modified with FeCl{sub 3} has a great performance in Hg removal.

Application of epithermal neutron activation analysis to investigate accumulation and adsorption of mercury by Spirulina platensis biomass

International Nuclear Information System (INIS)

Mosulishvili, L.M.; Belokobyl'skij, A.I.; Khizanishvili, A.I.; Frontas'eva, M.V.; Kirkesali, E.I.; Aksenova, N.G.

2004-01-01

Epithermal neutron activation analysis was used to study interaction of blue-green alga Spirulina platensis with toxic metal mercury. Various concentrations of Hg(II) were added to cell cultures in a nutrient medium. The dynamics of accumulation of Hg was investigated over several days in relation to Spirulina biomass growth. The process of Hg adsorption by Spirulina biomass was studied in short-time experiments. The isotherm of adsorption was carried out in Freindlich coordinates. Natural Spirulina biomass has potential to be used in the remediation of sewage waters at Hg concentrations ∼100 μg/1

Application of Epithermal Neutron Activation Analysis to Investigate Accumulation and Adsorption of Mercury by Spirulina platensis Biomass

CERN Document Server

Mosulishvili, L M; Khizanishvili, A I; Frontasyeva, M V; Kirkesali, E I; Aksenova, N G

2004-01-01

Epithermal neutron activation analysis was used to study interaction of blue-green alga Spirulina platensis with toxic metal mercury. Various concentrations of Hg(II) were added to cell cultures in a nutrient medium. The dynamics of accumulation of Hg was investigated over several days in relation to Spirulina biomass growth. The process of Hg adsorption by Spirulina biomass was studied in short-time experiments. The isotherm of adsorption was carried out in Freindlich coordinates. Natural Spirulina biomass has potential to be used in the remediation of sewage waters at Hg concentrations \\sim 100 {\\mu}g/l.

Iodide adsorption on the surface of chemically pretreated clinoptilolite

International Nuclear Information System (INIS)

Chmielewska-Horvatova, E.; Lesny, J.

1995-01-01

The possibility to use the monoionic Ag +- form (eventually Hg +- and Hg 2+ -forms) of clinoptilolite of domestic origin for radioactive iodide elimination from waters has been studied. The capacity of the monoforms of clinoptilolite towards iodide exceeds many times that of the capacity of clinoptilolite in natural form. Due to the low solubility product of AgI, Hg 2 I 2 and HgI 2 iodides generate precipitates on the zeolite surface. Rtg analyses of the silver form of clinoptilolite after sorption of iodide demonstrate the formation of new crystals on the zeolite surface. The influence of interfering anions on the adsorption capacity of silver clinoptilolite towards iodide was investigated, too. Kinetic curves of iodide desorption from the surface of silver and mercury clinoptilolite were compared. Simultaneously, adsorption isotherms for the systems aqueous iodide solution/Ag-, Hg-clinoptilolite were determined. (author) 6 refs.; 7 figs.; 4 tabs

COMBINED THEORETICAL AND EXPERIMENTAL INVESTIGATION OF MECHANISMS AND KINETICS OF VAPOR-PHASE MERCURY UPTAKE BY CARBONACOUES SURFACES

Energy Technology Data Exchange (ETDEWEB)

Radisav D. Vidic

2002-05-01

The first part of this study evaluated the application of a versatile optical technique to study the adsorption and desorption of model adsorbates representative of volatile polar (acetone) and non-polar (propane) organic compounds on a model carbonaceous surface under ultra high vacuum (UHV) conditions. The results showed the strong correlation between optical differential reflectance (ODR) and adsorbate coverage determined by temperature programmed desorption (TPD). ODR technique was proved to be a powerful tool to investigate surface adsorption and desorption from UHV to high pressure conditions. The effects of chemical functionality and surface morphology on the adsorption/desorption behavior of acetone, propane and mercury were investigated for two model carbonaceous surfaces, namely air-cleaved highly oriented pyrolytic graphite (HOPG) and plasma-oxidized HOPG. They can be removed by thermal treatment (> 500 K). The presence of these groups almost completely suppresses propane adsorption at 90K and removal of these groups leads to dramatic increase in adsorption capacity. The amount of acetone adsorbed is independent of surface heat treatment and depends only on total exposure. The effects of morphological heterogeneity is evident for plasma-oxidized HOPG as this substrate provides greater surface area, as well as higher energy binding sites. Mercury adsorption at 100 K on HOPG surfaces with and without chemical functionalities and topological heterogeneity created by plasma oxidation occurs through physisorption. The removal of chemical functionalities from HOPG surface enhances mercury physisorption. Plasma oxidation of HOPG provides additional surface area for mercury adsorption. Mercury adsorption by activated carbon at atmospheric pressure occurs through two distinct mechanisms, physisorption below 348 K and chemisorption above 348 K. No significant impact of oxygen functionalities was observed in the chemisorption region. The key findings of this study

Humic acid provenance influence to the adsorption capacity in uranium and thorium removal

Science.gov (United States)

Prasetyo, E.

2018-01-01

It is common knowledge that humic acid is organic compound without certain chemical composition since it is derived from different organic materials. Further this raises question whether the different humic acid sample used could lead to different adsorbent properties e.g. adsorption capacity. To address the problem, this paper is aimed to clarify the relation between the provenances of humic acid and synthesized adsorbent properties especially adsorption capacities by quantitative and qualitative functional groups determination including discussion on their effect to the metal ion adsorption mechanism using three humic acid samples. Two commercial samples were derived from recent compost while the other extracted from tertiary carbonaceous mudstone strata.

Structural properties and adsorption capacity of holocellulose aerogels synthesized from an alkali hydroxide-urea solution

Energy Technology Data Exchange (ETDEWEB)

Kwon, Gu-Joong; Kim, Dae-Young; Hwang, Jae-Hyun; Kang, Joo-Hyon [Dongguk University, Seoul (Korea, Republic of)

2014-05-15

A tulip tree was used to synthesize a holocellulose aerogel from an aqueous alkali hydroxide-urea solution with the substitution of an organic solvent followed by freeze-drying. For comparison, the synthesized holocellulose aerogels were divided into two groups according to the source of the hydrogel, an upper suspended layer and a bottom concentrated layer of the centrifuged solution of cellulose and NaOH/urea solvents. We investigated the effects of the temperature of the pre-cooled NaOH/urea solution (i.e., dissolution temperature) on the pore structure and the adsorption capacity of the holocellulose aerogel. A nano-fibrillar network structure of the holocellulose aerogel was observed, with little morphological difference in pore structure for different dissolution temperatures. Both micropores and mesopores were observed in the holocellulose aerogel. The specific surface area of the holocellulose aerogel was generally greater at lower dissolution temperatures. In a series of adsorption tests using methylene blue, the holocellulose aerogel showed the greatest adsorption capacity at the lowest dissolution temperature tested ( -2 .deg. C). However, the dissolution temperature generally had little effect on the adsorption capacity. The holocellulose aerogel produced from the upper suspended layer of the centrifuged hydrogel solution showed a greater porosity and adsorption capacity than the one produced from the bottom concentrated layer. Overall, the aerogel made by utilizing a delignified tulip tree display a high surface area and a high adsorption property, indicating its possible application in eco-friendly adsorption materials.

Structural properties and adsorption capacity of holocellulose aerogels synthesized from an alkali hydroxide-urea solution

International Nuclear Information System (INIS)

Kwon, Gu-Joong; Kim, Dae-Young; Hwang, Jae-Hyun; Kang, Joo-Hyon

2014-01-01

A tulip tree was used to synthesize a holocellulose aerogel from an aqueous alkali hydroxide-urea solution with the substitution of an organic solvent followed by freeze-drying. For comparison, the synthesized holocellulose aerogels were divided into two groups according to the source of the hydrogel, an upper suspended layer and a bottom concentrated layer of the centrifuged solution of cellulose and NaOH/urea solvents. We investigated the effects of the temperature of the pre-cooled NaOH/urea solution (i.e., dissolution temperature) on the pore structure and the adsorption capacity of the holocellulose aerogel. A nano-fibrillar network structure of the holocellulose aerogel was observed, with little morphological difference in pore structure for different dissolution temperatures. Both micropores and mesopores were observed in the holocellulose aerogel. The specific surface area of the holocellulose aerogel was generally greater at lower dissolution temperatures. In a series of adsorption tests using methylene blue, the holocellulose aerogel showed the greatest adsorption capacity at the lowest dissolution temperature tested ( -2 .deg. C). However, the dissolution temperature generally had little effect on the adsorption capacity. The holocellulose aerogel produced from the upper suspended layer of the centrifuged hydrogel solution showed a greater porosity and adsorption capacity than the one produced from the bottom concentrated layer. Overall, the aerogel made by utilizing a delignified tulip tree display a high surface area and a high adsorption property, indicating its possible application in eco-friendly adsorption materials.

Gas-phase formaldehyde adsorption isotherm studies on activated carbon: correlations of adsorption capacity to surface functional group density.

Science.gov (United States)

Carter, Ellison M; Katz, Lynn E; Speitel, Gerald E; Ramirez, David

2011-08-01

Formaldehyde (HCHO) adsorption isotherms were developed for the first time on three activated carbons representing one activated carbon fiber (ACF) cloth, one all-purpose granular activated carbon (GAC), and one GAC commercially promoted for gas-phase HCHO removal. The three activated carbons were evaluated for HCHO removal in the low-ppm(v) range and for water vapor adsorption from relative pressures of 0.1-0.9 at 26 °C where, according to the IUPAC isotherm classification system, the adsorption isotherms observed exhibited Type V behavior. A Type V adsorption isotherm model recently proposed by Qi and LeVan (Q-L) was selected to model the observed adsorption behavior because it reduces to a finite, nonzero limit at low partial pressures and it describes the entire range of adsorption considered in this study. The Q-L model was applied to a polar organic adsorbate to fit HCHO adsorption isotherms for the three activated carbons. The physical and chemical characteristics of the activated carbon surfaces were characterized using nitrogen adsorption isotherms, X-ray photoelectron spectroscopy (XPS), and Boehm titrations. At low concentrations, HCHO adsorption capacity was most strongly related to the density of basic surface functional groups (SFGs), while water vapor adsorption was most strongly influenced by the density of acidic SFGs.

Adsorption of selected pharmaceuticals and an endocrine disrupting compound by granular activated carbon. 1. Adsorption capacity and kinetics

Energy Technology Data Exchange (ETDEWEB)

Yu, Z.; Peldszus, S.; Huck, P.M. [University of Waterloo, Waterloo, ON (Canada). NSERC Chair in Water Treatment

2009-03-01

The adsorption of two representative PhACs (naproxen and carbamazepine) and one EDC (nonylphenol) were evaluated on two granular activated carbons (GAC) namely coal-based Calgon Filtrasorb 400 and coconut shell-based PICA CTIF TE. The primary objective was to investigate preloading effects by natural organic matter (NOM) on adsorption capacity and kinetics under conditions and concentrations (i.e., ng/L) relevant for drinking water treatment. Isotherms demonstrated that all compounds were significantly negatively impacted by NOM fouling. Adsorption capacity reduction was most severe for the acidic naproxen, followed by the neutral carbamazepine and then the more hydrophobic nonylphenol. The GAC with the wider pore size distribution had considerably greater NOM loading, resulting in lower adsorption capacity. Different patterns for the change in Freundlich KF and 1/n with time revealed different competitive mechanisms for the different compounds. Mass transport coefficients determined by short fixed-bed (SFB) tests with virgin and preloaded GAC demonstrated that film diffusion primarily controls mass transfer on virgin and preloaded carbon. Naproxen suffered the greatest deteriorative effect on kinetic parameters due to preloading, followed by carbamazepine, and then nonylphenol. A type of surface NOM/biofilm, which appeared to add an additional mass transfer resistance layer and thus reduce film diffusion, was observed. In addition, electrostatic interactions between NOM/biofilm and the investigated compounds are proposed to contribute to the reduction of film diffusion. A companion paper building on this work describes treatability studies in pilot-scale GAC adsorbers and the effectiveness of a selected fixed-bed model. 32 refs., 3 figs., 2 tabs.

Relationship between carbon microstructure, adsorption energy and hydrogen adsorption capacity at different temperatures

International Nuclear Information System (INIS)

Jacek Jagiello; Matthias Thommes

2005-01-01

Various microporous materials such as activated carbons, nano-tubes, synthetic microporous carbons as well as metal organic framework materials are being considered for hydrogen storage applications by means of physical adsorption. To develop materials of practical significance for hydrogen storage it is important to understand the relationships between pore sizes, adsorption energies and adsorption capacities. The pore size distribution (PSD) characterization is traditionally obtained from the analysis of nitrogen adsorption isotherms measured at 77 K. However, a portion of the pores accessible to H 2 may not be accessible to N 2 at this temperature. Therefore, it was recently proposed to use the DFT analysis of H 2 adsorption isotherms to characterize pore structure of materials considered for hydrogen storage applications. In present work, adsorption isotherms of H 2 and N 2 at cryogenic temperatures are used for the characterization of carbon materials. Adsorption measurements were performed with Autosorb 1 MP (Quantachrome Instruments, Boynton Beach, Florida, USA). As an example, Fig 1 compares PSDs calculated for the activated carbon sample (F400, Calgon Carbon) using combined H 2 and N 2 data, and using N 2 isotherm only. The nitrogen derived PSD does not include certain amount of micropores which are accessible to H 2 but not to N 2 molecules. Obviously, the difference in the calculated PSDs by the two methods will depend on the actual content of small micropores in a given sample. Carbon adsorption properties can also be characterized by the isosteric heat of adsorption, Qst, related to the adsorption energy and dependent on the carbon pore/surface structure. Fig 2 shows Qst data calculated using the Clausius-Clapeyron equation from H 2 isotherms measured at 77 K and 87 K for the carbon molecular sieve CMS 5A (Takeda), oxidized single wall nano-tubes (SWNT), and graphitized carbon black (Supelco). The Qst values decrease with increasing pore sizes. The

Amine-functionalized PVA-co-PE nanofibrous membrane as affinity membrane with high adsorption capacity for bilirubin.

Science.gov (United States)

Wang, Wenwen; Zhang, Hao; Zhang, Zhifeng; Luo, Mengying; Wang, Yuedan; Liu, Qiongzhen; Chen, Yuanli; Li, Mufang; Wang, Dong

2017-02-01

In this study, poly(vinyl alcohol-co-ethylene) (PVA-co-PE) nanofibrous membrane was activated by sodium hydroxide and cyanuric chloride, and then the activated membranes were functionalized by 1,3-propanediamine, hexamethylenediamine and diethylenetriamine to be affinity membranes for bilirubin removal, respectively. The chemical structures and morphologies of membranes were investigated by SEM, FTIR and XPS. And the adsorption ability of different amine-functionalized nanofibrous membranes for bilirubin was characterized. Furthermore, the effects of temperature, initial concentration of bilirubin, NaCl concentration and BSA concentration on the adsorption capacity for bilirubin of diethylenetriamine-functionalized nanofibrous membrane were studied. Results indicated that the adsorption capacity for bilirubin of diethylenetriamine-functionalized nanofibrous membrane could reach 85mg/g membrane when the initial bilirubin concentration was 200mg/L while the adsorption capacity could be increased to 110mg/g membrane if the initial bilirubin concentration was more than 400mg/L. The dynamic adsorption of diethylenetriamine-functionalized nanofibrous membrane showed that the ligands of amine groups on the membrane surface could be used as far as possible by recirculating the plasma with certain flow rates. Therefore, the diethylenetriamine-functionalized PVA-co-PE nanofibrous membrane possessed high adsorption capacity for bilirubin and it can be candidate as affinity membrane for bilirubin removal. Copyright © 2016. Published by Elsevier B.V.

Regenerative process for removal of mercury and other heavy metals from gases containing H.sub.2 and/or CO

Science.gov (United States)

Jadhav, Raja A [Naperville, IL

2009-07-07

A method for removal of mercury from a gaseous stream containing the mercury, hydrogen and/or CO, and hydrogen sulfide and/or carbonyl sulfide in which a dispersed Cu-containing sorbent is contacted with the gaseous stream at a temperature in the range of about 25.degree. C. to about 300.degree. C. until the sorbent is spent. The spent sorbent is contacted with a desorbing gaseous stream at a temperature equal to or higher than the temperature at which the mercury adsorption is carried out, producing a regenerated sorbent and an exhaust gas comprising released mercury. The released mercury in the exhaust gas is captured using a high-capacity sorbent, such as sulfur-impregnated activated carbon, at a temperature less than about 100.degree. C. The regenerated sorbent may then be used to capture additional mercury from the mercury-containing gaseous stream.

Suitability of adsorption isotherms for predicting the retention capacity of active slag filters removing phosphorus from wastewater.

Science.gov (United States)

Pratt, C; Shilton, A

2009-01-01

Active slag filters are an emerging technology for removing phosphorus (P) from wastewater. A number of researchers have suggested that adsorption isotherms are a useful tool for predicting P retention capacity. However, to date the appropriateness of using isotherms for slag filter design remains unverified due to the absence of benchmark data from a full-scale, field filter operated to exhaustion. This investigation compared the isotherm-predicted P retention capacity of a melter slag with the P adsorption capacity determined from a full-scale, melter slag filter which had reached exhaustion after five years of successfully removing P from waste stabilization pond effluent. Results from the standard laboratory batch test showed that P adsorption correlated more strongly with the Freundlich Isotherm (R(2)=0.97, Pretention capacity of 0.014 gP/kg slag; markedly lower than the 1.23 gP/kg slag adsorbed by the field filter. Clearly, the result generated by the isotherm bears no resemblance to actual field capacity. Scanning electron microscopy analysis revealed porous, reactive secondary minerals on the slag granule surfaces from the field filter which were likely created by weathering. This slow weathering effect, which generates substantial new adsorption sites, is not accounted for by adsorption isotherms rendering them ineffective in slag filter design.

Determination of Chemical States of Mercury on Activated Carbon Using XANES

International Nuclear Information System (INIS)

Takaoka, Masaki; Takeda, Nobuo; Oshita, Kazuyuki; Yamamoto, Takashi; Tanaka, Tsunehiro; Uruga, Tomoya

2007-01-01

Although the adsorption of mercury vapor onto activated carbon is a widely used technology to prevent environmental release, the adsorption mechanism is not clearly understood. In this study, we determined the chemical states of mercury on two kinds of activated carbon using X-ray absorption near-edge spectroscopy (XANES) to elucidate the adsorption mechanism. The adsorption experiments of elemental mercury onto activated carbon were conducted under air and nitrogen atmospheres at temperatures of 20 and 160 deg. C. Two types of activated carbon were prepared. X-ray absorption fine structure (XAFS) measurements were carried out on beamline BL01B1 at SPring-8. Hg-LIII edge XANES spectra suggested that chemical adsorption of elemental mercury on the activated carbon occurred in the 20-160 deg. C temperature range. According to the XANES spectra, a difference occurred in the chemical states of mercury between AC no. 1 and AC no. 2. The Hg XANES spectra on AC no. 1 were similar to those of Hg2Cl2 and HgS, and the Hg XANES spectra on AC no. 2 were similar to that of HgO, which suggested that nitric acid treatment removed sulfur from AC no. 1 and functional groups that were strong oxidizers on the surface of AC no. 2 created HgO. According to the EXAFS oscillation, a difference occurred in the chemical states of mercury on AC no. 1 between 20 and 160 deg. C. We found that impurities and oxidant functional groups on activated carbon play key roles in mercury adsorption

Integrated Removal of NOx with Carbon Monoxide as Reductant, and Capture of Mercury in a Low Temperature Selective Catalytic and Adsorptive Reactor

Energy Technology Data Exchange (ETDEWEB)

Neville Pinto; Panagiotis Smirniotis; Stephen Thiel

2010-08-31

Coal will likely continue to be a dominant component of power generation in the foreseeable future. This project addresses the issue of environmental compliance for two important pollutants: NO{sub x} and mercury. Integration of emission control units is in principle possible through a Low Temperature Selective Catalytic and Adsorptive Reactor (LTSCAR) in which NO{sub x} removal is achieved in a traditional SCR mode but at low temperature, and, uniquely, using carbon monoxide as a reductant. The capture of mercury is integrated into the same process unit. Such an arrangement would reduce mercury removal costs significantly, and provide improved control for the ultimate disposal of mercury. The work completed in this project demonstrates that the use of CO as a reductant in LTSCR is technically feasible using supported manganese oxide catalysts, that the simultaneous warm-gas capture of elemental and oxidized mercury is technically feasible using both nanostructured chelating adsorbents and ceria-titania-based materials, and that integrated removal of mercury and NO{sub x} is technically feasible using ceria-titania-based materials.

Mercury emissions control technologies for mixed waste thermal treatment

International Nuclear Information System (INIS)

Chambers, A.; Knecht, M.; Soelberg, N.; Eaton, D.

1997-01-01

EPA has identified wet scrubbing at low mercury feedrates, as well as carbon adsorption via carbon injection into the offgas or via flow through fixed carbon beds, as control technologies that can be used to meet the proposed Maximum Achievable Control Technology (MACT) rule limit for mercury emissions from hazardous waste incinerators. DOE is currently funding demonstrations of gold amalgamation that may also control mercury to the desired levels. Performance data from a variety of sources was reviewed to determine ranges of achievable mercury control. Preliminary costs were estimated for using these technologies to control mercury emissions from mixed waste incineration. Mercury emissions control for mixed waste incineration may need to be more efficient than for incineration of other hazardous wastes because of higher mercury concentrations in some mixed waste streams. However, mercury control performance data for wet scrubbing and carbon adsorption is highly variable. More information is needed to demonstrate control efficiencies that are achievable under various design and operating conditions for wet scrubbing, carbon adsorption, and gold amalgamation technologies. Given certain assumptions made in this study, capital costs, operating costs, and lifecycle costs for carbon injection, carbon beds, and gold amalgamation generally vary for different assumed mercury feedrates and for different offgas flowrates. Assuming that these technologies can in fact provide the necessary mercury control performance, each of these technologies may be less costly than the others for certain mercury feedrates and the offgas flowrates

Relationship between carbon microstructure, adsorption energy and hydrogen adsorption capacity at different temperatures

International Nuclear Information System (INIS)

Jagiello, J.; Thommes, M.

2005-01-01

Various microporous materials such as activated carbons, nano-tubes, synthetic micro-porous carbons as well as metal organic framework materials are being considered for hydrogen storage applications by means of physical adsorption. To develop materials of practical significance for hydrogen storage it is important to understand the relationships between pore sizes, adsorption energies and adsorption capacities. The pore size distribution (PSD) characterization is traditionally obtained from the analysis of nitrogen adsorption isotherms measured at 77 K. However, a portion of the pores accessible to H 2 may not be accessible to N 2 at this temperature. Therefore, it was recently proposed to use the DFT analysis of H 2 adsorption isotherms to characterize pore structure of materials considered for hydrogen storage applications [1]. In present work, adsorption isotherms of H 2 and N 2 at cryogenic temperatures are used for the characterization of carbon materials. Adsorption measurements were performed with Autosorb 1 MP [Quantachrome Instruments, Boynton Beach, Florida, USA]. As an example, Fig 1 compares PSDs calculated for the activated carbon sample (F400, Calgon Carbon) using combined H 2 and N 2 data, and using N 2 isotherm only. The nitrogen derived PSD does not include certain amount of micro-pores which are accessible to H 2 but not to N 2 molecules. Obviously, the difference in the calculated PSDs by the two methods will depend on the actual content of small micro-pores in a given sample. Carbon adsorption properties can also be characterized by the isosteric heat of adsorption, Qst, related to the adsorption energy and dependent on the carbon pore/surface structure. Fig 2 shows Qst data calculated using the Clausius-Clapeyron equation from H 2 isotherms measured at 77 K and 87 K for the carbon molecular sieve CMS 5A (Takeda), oxidized single wall nano-tubes (SWNT) [2], and graphitized carbon black (Supelco). The Qst values decrease with increasing pore

Adsorption of arsenate on soils. Part 2: Modeling the relationship between adsorption capacity and soil physiochemical properties using 16 Chinese soils

International Nuclear Information System (INIS)

Jiang Wei; Zhang, Shuzhen; Shan Xiaoquan; Feng Muhua; Zhu Yongguan; McLaren, Ron G.

2005-01-01

An attempt has been made to elucidate the effects of soil properties on arsenate adsorption by modeling the relationships between adsorption capacity and the properties of 16 Chinese soils. The model produced was validated against three Australian and three American soils. The results showed that nearly 93.8% of the variability in arsenate adsorption on the low-energy surface could be described by citrate-dithionite extractable Fe (Fe CD ), clay content, organic matter content (OM) and dissolved organic carbon (DOC); nearly 87.6% of the variability in arsenate adsorption on the high-energy surface could be described by Fe CD , DOC and total arsenic in soils. Fe CD exhibited the most important positive influence on arsenate adsorption. Oxalate extractable Al (Al OX ), citrate-dithionite extractable Al (Al CD ), extractable P and soil pH appeared relatively unimportant for adsorption of arsenate by soils. - Citrate-dithionite extractable Fe has the most important positive influence on arsenate adsorption on soils

N-doping effectively enhances the adsorption capacity of biochar for heavy metal ions from aqueous solution.

Science.gov (United States)

Yu, Wenchao; Lian, Fei; Cui, Guannan; Liu, Zhongqi

2018-02-01

N-doping was successfully employed to improve the adsorption capacity of biochar (BC) for Cu 2+ and Cd 2+ by direct annealing of crop straws in NH 3 . The surface N content of BC increased more than 20 times by N-doping; meanwhile the content of oxidized-N was gradually diminished but graphitic-N was formed and increased with increasing annealing temperature and duration time. After N-doping, a high graphitic-N percentage (46.4%) and S BET (418.7 m 2 /g) can be achieved for BC. As a result, the N-doped BC exhibited an excellent adsorption capacity for Cu 2+ (1.63 mmol g -1 ) and Cd 2+ (1.76 mmol g -1 ), which was up to 4.0 times higher than that of the original BC. Furthermore, the adsorption performance of the N-doped BC remained stable even at acidic conditions. A positive correlation can be found between adsorption capacity with the graphitic N content on BC surface. The surface chemistry of N-doped BC before and after the heavy metal ions adsorption was carefully examined by XPS and FTIR techniques, which indicated that the adsorption mechanisms mainly included cation-π bonding and complexation with graphitic-N and hydroxyl groups of carbon surfaces. Copyright © 2017 Elsevier Ltd. All rights reserved.

Sulfur rich microporous polymer enables rapid and efficient removal of mercury(II) from water.

Science.gov (United States)

Xu, Dan; Wu, Winston Duo; Qi, Hao-Jun; Yang, Rui-Xia; Deng, Wei-Qiao

2018-04-01

Design and synthesis of adsorbents for efficient decontamination of hazardous contaminants Hg 2+ from wastewater, based on a facile and economical strategy, is an attractive target. Here, a novel sulfur rich microporous polymer (sulfur content of 31.4 wt %) with high surface area as well as densely populated sulfur atom with fast accessibility was reported to remove mercury (II) from water. The as prepared polymer (SMP) exhibited high binding affinity, high adsorption capacities, rapid adsorption kinetics, and good recyclability for Hg 2+ . The adsorption capacity of SMP was 595.2 mg g -1 . Furthermore, SMP could reduce trace concentrations of Hg 2+ from 200 p. p. b. to a level below drinking water standards (2 p. p. b.) within 3 min. This work allows large-scale production of sulfur rich porous materials for the practical application in water treatment. Copyright © 2017 Elsevier Ltd. All rights reserved.

Fugitive gas adsorption capacity of biomass and animal-manure derived biochars

Science.gov (United States)

This research characterized and investigated ammonia and hydrogen sulfide gas adsorption capacities of low- and high-temperature biochars made from wood shavings and chicken litter. The biochar samples were activated with steam or phosphoric acid. The specific surface areas and pore volumes of the a...

Adsorption capacity of methylene blue, an organic pollutant, by montmorillonite clay

KAUST Repository

Feddal, I.; Ramdani, Amina; Taleb, Safia; Gaigneaux, E. M.; Batis, Narjè s Harrouch; Ghaffour, NorEddine

2013-01-01

The isotherms and kinetics of the adsorption of a cationic dye in aqueous solution, methylene blue, on a local Algerian montmorillonite clay mineral (raw, sodium and thermally activated at 300 and 500°C) were determined experimentally. Various parameters influencing the adsorption were optimized, mainly solid-liquid contact time, mass of adsorbent, initial concentration of dye, pH of the solution and temperature. Results showed that the adsorption kinetics were fast: 30 min for the raw clay mineral, and 20 min for sodium clay mineral (SC) and thermally activated at 300°C, whereas with the clay mineral calcined at 500°C, the equilibrium was reached after 150 min only. The maximum adsorption capacity was reached at pH 6.6. Results deducted from the adsorption isotherms also showed that the retention follows the Langmuir model. In addition, it was found that the kinetics were in the order of 2 (K = 2.457 × 106 g/mg.h) for sodium clay and were limited by an intra-particle diffusion. SC was found to be a better adsorbent to remove methylene blue from industrial wastewater. © 2013 Balaban Desalination Publications. All rights reserved.

Adsorption capacity of methylene blue, an organic pollutant, by montmorillonite clay

KAUST Repository

Feddal, I.

2013-11-19

The isotherms and kinetics of the adsorption of a cationic dye in aqueous solution, methylene blue, on a local Algerian montmorillonite clay mineral (raw, sodium and thermally activated at 300 and 500°C) were determined experimentally. Various parameters influencing the adsorption were optimized, mainly solid-liquid contact time, mass of adsorbent, initial concentration of dye, pH of the solution and temperature. Results showed that the adsorption kinetics were fast: 30 min for the raw clay mineral, and 20 min for sodium clay mineral (SC) and thermally activated at 300°C, whereas with the clay mineral calcined at 500°C, the equilibrium was reached after 150 min only. The maximum adsorption capacity was reached at pH 6.6. Results deducted from the adsorption isotherms also showed that the retention follows the Langmuir model. In addition, it was found that the kinetics were in the order of 2 (K = 2.457 × 106 g/mg.h) for sodium clay and were limited by an intra-particle diffusion. SC was found to be a better adsorbent to remove methylene blue from industrial wastewater. © 2013 Balaban Desalination Publications. All rights reserved.

Ultra-high adsorption capacity of zeolitic imidazole framework-67 (ZIF-67) for removal of malachite green from water.

Science.gov (United States)

Lin, Kun-Yi Andrew; Chang, Hsuan-Ang

2015-11-01

Zeolitic imidazole frameworks (ZIFs), a new class of adsorbents, are proposed to adsorb Malachite Green (MG) in water. Particularly, ZIF-67 was selected owing to its stability in water and straightforward synthesis. The as-synthesized ZIF-67 was characterized and used to adsorb MG from water. Factors affecting the adsorption capacity were investigated including mixing time, temperature, the presence of salts and pH. The kinetics, adsorption isotherm and thermodynamics of the MG adsorption to ZIF-67 were also studied. The adsorption capacity of ZIF-67 for MG could be as high as 2430mgg(-1) at 20°C, which could be improved at the higher temperatures. Such an ultra-high adsorption capacity of ZIF-67 was almost 10-times of those of conventional adsorbents, including activated carbons and biopolymers. A mechanism for the high adsorption capacity was proposed and possibly attributed to the π-π stacking interaction between MG and ZIF-67. ZIF-67 also could be conveniently regenerated by washing with ethanol and the regeneration efficiency could remain 95% up to 4 cycles of the regeneration. ZIF-67 was also able to remove MG from the aquaculture wastewater, in which MG can be typically found. These features enable ZIF-67 to be one of the most effective and promising adsorbent to remove MG from water. Copyright © 2015 Elsevier Ltd. All rights reserved.

Mesoporous g-C₃N₄ Nanosheets: Synthesis, Superior Adsorption Capacity and Photocatalytic Activity.

Science.gov (United States)

Li, Dong-Feng; Huang, Wei-Qing; Zou, Lan-Rong; Pan, Anlian; Huang, Gui-Fang

2018-08-01

Elimination of pollutants from water is one of the greatest challenges in resolving global environmental issues. Herein, we report a high-surface-area mesoporous g-C3N4 nanosheet with remarkable high adsorption capacity and photocatalytic performance, which is prepared through directly polycondensation of urea followed by a consecutive one-step thermal exfoliation strategy. This one-pot method to prepare mesoporous g-C3N4 nanosheet is facile and rapid in comparison with others. The superior adsorption capacity of the fabricated mesoporous g-C3N4 nanostructures is demonstrated by a model organic pollutant-methylene blue (MB), which is up to 72.2 mg/g, about 6 times as that of the largest value of various g-C3N4 adsorbents reported so far. Moreover, this kind of porous g-C3N4 nanosheet exhibits high photocatalytic activity to MB and phenol degradation. Particularly, the regenerated samples show excellent performance of pollutant removal after consecutive adsorption/degradation cycles. Therefore, this mesoporous g-C3N4 nanosheet may be an attractive robust metal-free material with great promise for organic pollutant elimination.

Study on the Adsorption Capacities for Airborne Particulates of Landscape Plants in Different Polluted Regions in Beijing (China

Directory of Open Access Journals (Sweden)

Wei-Kang Zhang

2015-08-01

Full Text Available Urban landscape plants are an important component of the urban ecosystem, playing a significant role in the adsorption of airborne particulates and air purification. In this study, six common landscape plants in Beijing were chosen as research subjects, and the adsorption capacities for each different plant leaf and the effects of the leaf structures for the adsorption capacities for particulates were determined. Preliminary results show that needle-leaved tree species adsorbed more airborne particulates than broad-leaved tree species for the same leaf area. Pinus tabuliformis exhibits the highest adsorption capacity, at 3.89 ± 0.026 μg·cm−2, almost two times as much as that of Populus tomentosa (2.00 ± 0.118 μg·cm−2. The adsorption capacities for PM10 of the same tree species leaves, in different polluted regions had significant differences, and the adsorption capacities for PM10 of the tree species leaf beside the Fifth Ring Road were higher than those of the tree species leaves in the Botanical Garden, although the adsorption capacities for PM2.5 of the same tree species in different polluted regions had no significant differences. By determining the soluble ion concentrations of the airborne particulates in two regions, it is suggested that the soluble ion concentrations of PM10 in the atmosphere in the Botanical Garden and beside the Fifth Ring Road have significant differences, while those of PM2.5 in the atmosphere had no significant differences. In different polluted regions there are significant adaptive changes to the leaf structures, and when compared with slightly polluted region, in the seriously polluted region the epidermis cells of the plant leaves shrinked, the surface textures of the leaves became rougher, and the stomas’ frequency and the pubescence length increased. Even though the plant leaves exposed to the seriously polluted region changed significantly, these plants can still grow normally and healthily.

Adsorption Capacity of a Volcanic Rock—Used in ConstructedWetlands—For Carbamazepine Removal, and Its Modification with Biofilm Growth

Directory of Open Access Journals (Sweden)

Allan Tejeda

2017-09-01

Full Text Available In this study, the aim was to evaluate the adsorption capacity of a volcanic rock commonly used in Mexico as filter medium in constructed wetlands (locally named tezontle for carbamazepine (CBZ adsorption, as well as to analyze the change in its capacity with biofilm growth. Adsorption essays were carried out under batch conditions by evaluating two particle sizes of tezontle, two values of the solution pH, and two temperatures; from these essays, optimal conditions for carbamazepine adsorption were obtained. The optimal conditions (pH 8, 25 °C and 0.85–2.0 mm particle-size were used to evaluate the adsorption capacity of tezontle with biofilm, which was promoted through tezontle exposition to wastewater in glass columns, for six months. The maximum adsorption capacity of clean tezontle was 3.48 µg/g; while for the tezontle with biofilm, the minimum value was 1.75 µg/g (after the second week and the maximum, was 3.3 µg/g (after six months with a clear tendency of increasing over time. The adsorption kinetic was fitted to a pseudo-second model for both tezontle without biofilm and with biofilm, thus indicating a chemisorption process. On clean tezontle, both acid active sites (AAS and basic active sites (BAS were found in 0.087 and 0.147 meq/g, respectively. The increase in the adsorption capacity of tezontle with biofilm, along the time was correlated with a higher concentration of BAS, presumably from a greater development of biofilm. The presence of biofilm onto tezontle surface was confirmed through FTIR and FE-SEM. These results confirm the essential role of filter media for pharmaceutical removal in constructed wetlands (CWs.

Improved CO_2 adsorption capacity and cyclic stability of CaO sorbents incorporated with MgO

International Nuclear Information System (INIS)

Farah Diana Mohd Daud; Kumaravel Vignesh; Srimala Sreekantan; Abdul Rahman Mohamed

2016-01-01

Calcium oxide (CaO) sorbents incorporated with magnesium oxide (MgO) were synthesized using a co-precipitation route. The sorbents were prepared with different MgO concentrations (from 5 wt% to 30 wt%). The as-prepared sorbents were characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDX) and BET surface area analysis techniques. The sintering effect of CaO sorbents was decreased after the incorporation of MgO. The sorbents with 5 wt% and 10 wt% of MgO retained their CO_2 adsorption capacity over multiple cycles. Most importantly, CaO with 10 wt% MgO showed constant CO_2 adsorption capacity over 30 carbonation cycles. The results revealed that CaO with 10 wt% MgO is sufficient to produce sorbents with high surface area, good structural stability and enhanced CO_2 adsorption capacity. (authors)

Complexes of DOTA-bisphosphonate conjugates: probes for determination of adsorption capacity and affinity constants of hydroxyapatite.

Science.gov (United States)

Vitha, Tomas; Kubícek, Vojtech; Hermann, Petr; Kolar, Zvonimir I; Wolterbeek, Hubert Th; Peters, Joop A; Lukes, Ivan

2008-03-04

The adsorption on hydroxyapatite of three conjugates of a bisphosphonate and a macrocycle having C1, C2, and C3 spacers and their terbium complexes was studied by the radiotracer method using 160Tb as the label. The radiotracer-containing complex of the conjugate with the C3 spacer was used as a probe for the determination of the adsorption parameters of other bisphosphonates that lack a DOTA unit. A physicochemical model describing the competitive adsorption was successfully applied in the fitting of the obtained data. The maximum adsorption capacity of bisphosphonates containing bulky substituents is determined mainly by their size. For bisphosphonates having no DOTA moiety, the maximum adsorption capacity is determined by the electrostatic repulsion between negatively charged bisphosphonate groups. Compounds with a hydroxy or amino group attached to the alpha-carbon atom show higher affinities. Macrocyclic compounds containing a short spacer between the different bisphosphonic acid groups and the macrocyclic unit exhibit high affinities, indicating a synergic effect of the bisphosphonic and the macrocyclic groups during adsorption. The competition method described uses a well-characterized complex and allows a simple evaluation of the adsorption behavior of bisphosphonates. The application of the macrocycle-bisphosphonate conjugates allows easy radiolabeling via complexation of a suitable metal isotope.

Influence of diatomite microstructure on its adsorption capacity for Pb(II

Directory of Open Access Journals (Sweden)

Nenadović S.

2009-01-01

Full Text Available The effect of microstructural changes caused by mechanical modification on adsorption properties of diatomite samples were investigated. The microstructure has been characterized by X-ray diffraction (XRD, scanning electron microscopy (SEM and atomic force microscopy (AFM while the degree of metal adsorption was evaluated by Inductively Coupled Plasma Atomic Emission Spectrometry (ICP AES. The results show that metal sorption capacity of diatomite is considerably improved after mechanical modification and it can be attributed to amorphysation of the material. Immobilization efficiency increased from 22% for untreated to 81% for the treated sample after 5h at BPR 4.This qualifies natural diatomite as a material for wastewater remediation.

COMBINED THEORETICAL AND EXPERIMENTAL INVESTIGATION OF MECHANISMS AND KINETICS OF VAPOR-PHASE MERCURY UPTAKE BY CARBONACEOUS SURFACES; ANNUAL

International Nuclear Information System (INIS)

Radisav D. Vidic; Eric V. Borguet; Karl J. Johnson

2000-01-01

The overall goal of this research program is to gain fundamental understanding of the important chemistry and physics involved in mercury adsorption on carbonaceous surfaces. This knowledge will then be used to optimize adsorption processes and operating conditions to maximize the uptake of mercury within the required contact time. An additional long-term benefit of this research is the basic understanding of the Hg adsorption process, which may facilitate the design of new adsorbents for more efficient and cost-effective removal of Hg from a variety of effluent streams. Molecular modeling of the adsorption of Hg on carbonaceous surfaces will greatly increase the insight into the physics of the adsorption process and combined with in situ rate measurements of mercury adsorption and desorption (conventional and pulsed laser) on graphite using linear and nonlinear optical probes with real time optical resolution have the potential to provide fundamental insight into the process of mercury uptake by carbonaceous surfaces. Besides accurate assessment of key parameters influencing adsorption equilibrium, fundamental understanding of the kinetics of mercury adsorption, desorption, and diffusion will be developed in this study. These key physical and chemical processes postulated through molecular modeling efforts and verified by in situ measurements will be utilized to select (or develop) promising sorbents for mercury control, which will be tested under dynamic conditions using simulated flue gas

The effect of food and ice cream on the adsorption capacity of paracetamol to high surface activated charcoal

DEFF Research Database (Denmark)

Høgberg, Lotte Christine Groth; Angelo, Helle Riis; Christophersen, Anne Bolette

2003-01-01

, the reductions compared to control (Hoegberg et al. 2002) varied between 11% and 26%. Even though a reduction in drug adsorption to activated charcoal was observed when food mixture or ice cream was added, the remaining adsorption capacity of both types of activated charcoal theoretically was still able......The effect of added food mixture (as if food was present in the stomach of an intoxicated patient) or 4 different types of ice cream (added as a flavouring and lubricating agent) on the adsorption of paracetamol (acetaminophen) to 2 formulations of activated charcoal was determined in vitro......, and paracetamol were mixed with either food mixture or ice cream followed by one hr incubation. The maximum adsorption capacity of paracetamol to activated charcoal was calculated using Langmuirs adsorption isotherm. Paracetamol concentration was analyzed using high pressure liquid chromatography. In the presence...

Adsorption of mercury from aqueous solutions using palm oil fuel ash as an adsorbent - batch studies

Science.gov (United States)

Imla Syafiqah, M. S.; Yussof, H. W.

2018-03-01

Palm oil fuel ash (POFA) is one of the most abundantly produced waste materials. POFA is widely used by the oil palm industry which was collected as ash from the burning of empty fruit bunches fiber (EFB) and palm oil kernel shells (POKS) in the boiler as fuel to generate electricity. Mercury adsorption was conducted in a batch process to study the effects of contact time, initial Hg(II) ion concentration, and temperature. In this study, POFA was prepared and used for the removal of mercury(II) ion from the aqueous phase. The effects of various parameters such as contact time (0- 360 min), temperature (15 – 45 °C) and initial Hg(II) ion concentration (1 – 5 mg/L) for the removal of Hg(II) ion were studied in a batch process. The surface characterization was examined by scanning electron microscopy (SEM) and particle size distribution analysis. From this study, it was found that the highest Hg(II) ion removal was 99.60 % at pH 7, contact time of 4 h, initial Hg(II) ion concentration of 1 mg/L, adsorbent dosage 0.25 g and agitation speed of 100 rpm. The results implied that POFA has the potential as a low-cost and environmental friendly adsorbent for the removal of mercury from aqueous solution.

Plasma-assisted adsorption of elemental mercury on CeO2/TiO2 at low temperatures

Science.gov (United States)

Liu, Lu; Zheng, Chenghang; Gao, Xiang

2017-11-01

Mercury is a kind of pollutants contained in flue gas which is hazardous for human beings. In this work, CeO2 was packed in the discharge zone of a plasma reactor to adsorb elemental mercury at low temperatures. Plasma-catalyst reactor can remove Hg0 efficiently with CeO2/TiO2 catalysts packed in the discharge zone. The Hg0 concentration continued to decrease gradually when the plasma was turned on, but not sank rapidly. This tendency was different with other catalysts. The treatment of plasma to CeO2/TiO2 catalysts has a promotion effect on the adsorption of Hg0. Plasma has the effect of changing the surface properties of the catalysts and the changes would restitute if the condition changed. The long-running test demonstrated that this method is an effective way to remove Hg0. The removal efficiency remained at above 99% throughout 12 hours when plasma had been turned on (15kV, 0.5 g packed CeO2/TiO2).

Porous carbon with small mesoporesas an ultra-high capacity adsorption medium

Science.gov (United States)

Gao, Biaofeng; Zhou, Haitao; Chen, De; Yang, Jianhong

2017-10-01

Resins (732-type), abundant and inexpensive resources were used to prepare porous carbon with small mesopores (CSM) by carbonization and post-chemical-activation with potassium hydroxide (KOH). The N2 adsorption measurements revealed that CSM had high surface areas (1776.5 m2 g-1), large pore volumes (1.10 cm3 g-1), and nearly optimal narrow small mesopore sizes ranging from 2 to 7 nm. CSM was used as adsorbent to investigate the adsorption behavior for Rhodamine B (RhB). Due to the optimal pore size distributions (PSD), intensive-stacking interaction, S-doped, and electrostatic attraction, the CSM exhibited an ultra-high-capacity of 1590 mg g-1 for RhB in aqueous solutions.

Investigation of adsorption performance deterioration in silica gel–water adsorption refrigeration

International Nuclear Information System (INIS)

Wang Dechang; Zhang Jipeng; Xia Yanzhi; Han Yanpei; Wang Shuwei

2012-01-01

Highlights: ► Adsorption deterioration of silica gel in refrigeration systems is verified. ► Possible factors to cause such deterioration are analyzed. ► Specific surface area, silanol content and adsorption capacity are tested. ► The pollution is the primary factor to decline the adsorption capacity. ► Deteriorated samples are partly restored after being processed by acid solution. - Abstract: Silica gel acts as a key role in adsorption refrigeration systems. The adsorption deterioration must greatly impact the performance of the silica gel–water adsorption refrigeration system. In order to investigate the adsorption deterioration of silica gel, many different silica gel samples were prepared according to the application surroundings of silica gel in adsorption refrigeration systems after the likely factors to cause such deterioration were analyzed. The specific surface area, silanol content, adsorption capacity and pore size distribution of those samples were tested and the corresponding adsorption isotherms were achieved. In terms of the experimental data comparisons, it could be found that there are many factors to affect the adsorption performance of silica gel, but the pollution was the primary one to decline the adsorption capacity. In addition, the adsorption performance of the deteriorated samples after being processed by acid solution was explored in order to find the possible methods to restore its adsorption performance.

Removal of elemental mercury by bamboo charcoal impregnated with H{sub 2}O{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Zengqiang Tan; Jianrong Qiu; Hancai Zeng; Hao Liu; Jun Xiang [Huazhong University of Science and Technology, Wuhan (China). Key Laboratory of Coal Combustion

2011-04-15

Mercury emission from coal combustion is an increasing environmental concern due to its high volatility and toxicity, and activated carbon (AC) adsorption has been proven an effective mercury-control method, with high-cost limit. The renewable bioresource of bamboo constitutes an important precursor for activated carbon, and the bamboo charcoal (BC) may act as low-cost sorbent used in the mercury-control. The adsorptive potential of BC and modified BC using H{sub 2}O{sub 2} for elemental mercury was investigated for the first time through a parametric study conducted with a bench-scale bed. The effects of pore structure and surface chemistry were investigated based on BET, XPS. Which suggest that BC materials have excellent adsorption potential for elemental mercury, especially after modified by H{sub 2}O{sub 2}. The modification using H{sub 2}O{sub 2} altered the physical and chemical properties of BC materials, making the sorbents more effective in mercury adsorption even at a relative higher temperature, and the enhancing-effect was more obvious with increasing H{sub 2}O{sub 2}. 32 refs., 6 figs., 5 tabs.

Enhancing adsorption capacity of toxic malachite green dye through chemically modified breadnut peel: equilibrium, thermodynamics, kinetics and regeneration studies.

Science.gov (United States)

Chieng, Hei Ing; Lim, Linda B L; Priyantha, Namal

2015-01-01

Breadnut skin, in both its unmodified (KS) and base-modified (BM-KS) forms, was investigated for its potential use as a low-cost adsorbent for the removal of toxic dye, malachite green (MG). Characterization of the adsorbents was carried out using scanning electron microscope, X-ray fluorescence and Fourier transform infra-red spectroscopy. Batch adsorption experiments, carried out under optimized conditions, for the adsorption of MG were fitted using five isotherm models (Langmuir, Freundlich, Dubinin-Radushkevich, Temkin and Sips) and six error functions to determine the best-fit model. The adsorption capacity was greatly enhanced when breadnut skin was chemically modified with NaOH, leading to an adsorption capacity of 353.0 mg g(-1), that was far superior to most reported adsorbents for the removal of MG. Thermodynamics studies indicated that the adsorption of MG was spontaneous on KS and BM-KS, and the reactions were endothermic and exothermic, respectively. Kinetics studies showed that both followed the pseudo-second order. Regeneration experiments on BM-KS indicated that its adsorption capacity was still maintained at>90% even after five cycles. It can be concluded that NaOH-modified breadfruit skin has great potential to be utilized in real-life application as a low-cost adsorbent for the removal of MG in wastewater treatment.

Effect of carbonation temperature on CO_2 adsorption capacity of CaO derived from micro/nanostructured aragonite CaCO_3

International Nuclear Information System (INIS)

Hlaing, Nwe Ni; Sreekantan, Srimala; Hinode, Hirofumi; Kurniawan, Winarto; Thant, Aye Aye; Othman, Radzali; Mohamed, Abdul Rahman; Salime, Chris

2016-01-01

Recent years, CaO-based synthetic materials have been attracted attention as potential adsorbents for CO_2 capture mainly due to their high CO_2 adsorption capacity. In this study, micro/nanostructured aragonite CaCO_3 was synthesized by a simple hydrothermal method with using polyacrylamide (PAM). The structural, morphological and thermal properties of the synthesized sample were investigated by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM) and thermogravimetry analysis (TG-DTA). The XRD and FESEM results showed that the obtained sample was aragonite CaCO_3 with aggregated nanorods and microspheres composed of nanorods. A TG-DTA apparatus with Thermoplus 2 software was used to investigate the effect of carbonation temperature on the CO_2 adsorption capacity of CaO derived from aragonite CaCO_3 sample. At 300 °C, the sample reached the CO_2 adsorption capacity of 0.098 g-CO_2/g-adsorbent, whereas the sample achieved the highest capacity of 0.682 g-CO_2/g-adsorbent at 700 °C. The results showed that the carbonation temperature significantly influenced on the CO_2 adsorption capacity of the CaO derived from aragonite CaCO_3.

Modification of cyanobacterial bloom-derived biomass using potassium permanganate enhanced the removal of microcystins and adsorption capacity toward cadmium (II)

International Nuclear Information System (INIS)

Shao, Jihai; Gu, Ji-Dong; Peng, Liang; Luo, Si; Luo, Huili; Yan, Zhiyong; Wu, Genyi

2014-01-01

Highlights: • Potassium permanganate removed microcystins in the cyanobacterial bloom-derived biomass (CBDB). • Potassium permanganate oxidation caused the transformation of hydroxyl to carboxyl on the CBDB. • Manganese dioxide was formed on the surface of CBDB. • Potassium permanganate oxidation process increased the adsorption capacity of CBDB toward Cd(II). - Abstract: Cyanobacterial biomass shows high adsorption capacity toward heavy metal ions. However, the cyanotoxins in the cyanobacterial biomass inhibit its application in heavy metals removal. In order to safely and effectively remove Cd(II) from water using cyanobacterial bloom-derived biomass (CBDB), KMnO 4 was used to modify CBDB. The results indicated that the microcystins in the CBDB were successfully removed by KMnO 4 . Potassium permanganate oxidation caused the transformation of hydroxyl to carboxyl on the CBDB, and formed manganese dioxide on the surface of CBDB. The oxidized CBDB showed higher adsorption capacity toward Cd(II) than that of unoxidized treatment. The optimal KMnO 4 concentration for increasing the adsorption capacity of CBDB toward Cd(II) was 0.2 g/L. The adsorption isotherm of Cd(II) by oxidized- or unoxidized-CBDB was well fitted by Langmuir model, indicating that the adsorption of Cd(II) by CBDB was monolayer adsorption. The desorption ratio of Cd(II) from oxidized CBDB was higher than that from unoxidized CBDB in the desorption process using NH 4 NO 3 and EDTA as desorbent. The results presented in this study suggest that KMnO 4 modified CBDB may be used as a safe and high efficient adsorbent in Cd(II) removal from water

Synthesis and characterization of sulfur-functionalized silica nanocapsules as mercury adsorbents

Science.gov (United States)

Palaniappan, Thenappan; Saman, Norasikin; Mat, Hanapi; Johari, Khairiraihanna

2017-12-01

Sulfur functionalized silica nanocapsules (S-SiNC) was successfully synthesized and characterized as a potential adsorbent for industrial applications. The synthesis of S-SiNC was carried out using the mircoemulsion templating method using cetyltrimethylammonium bromide (CTAB) as cationic surfactant, toluene as co-solvent, ammonia solution as catalyst, and tetraethylorthosilicate (TEOS) as the silica base. The S-SiNC adsorbent was characterized using Transmission Electron Microscope, Fourier Transformed Infra Red spectroscopy and nitrogen adsorption/desorption analysis. The physical and chemical properties of the SiNC changed as a result of the functionalization, hence affecting the extent of Hg(II) adsorption. The S-SiNCs were also tested in mercury ion [Hg(II)] adsorption via batch adsorption process with variation in initial Hg (II) concentration. It was found that there is a significant improvement in Hg(II) adsorption performance after being functionalized with elemental sulfur. The highest Hg(II) adsorption capacity was obtained for S-SiNC (107.875 mg/g), which significantly outperformed the blank SiNC. The experimental data obtained was found to be fitting well to the Langmuir isotherm model (R2= 0.979) compared to Freundlich isotherm model. Thus, the results demonstrated the potential application of sulfur functionalized silica nanocapsules as adsorbent in industrial applications.

Chloride Ion Adsorption Capacity of Anion Exchange Resin in Cement Mortar

Directory of Open Access Journals (Sweden)

Yunsu Lee

2018-04-01

Full Text Available This paper presents the effect of anion exchange resin (AER on the adsorption of chloride ions in cement mortar. The kinetic and equilibrium behaviors of AER were investigated in distilled water and Ca(OH2 saturated solutions, and then the adsorption of chloride ions by the AER in the mortar specimen was determined. The AER was used as a partial replacement for sand in the mortar specimen. The mortar specimen was coated with epoxy, except for an exposed surface, and then immersed in a NaCl solution for 140 days. The chloride content in the mortar specimen was characterized by energy dispersive X-ray fluorescence analysis and electron probe microanalysis. The results showed that the AER could adsorb the chloride ions from the solution rapidly but had a relatively low performance when the pH of its surrounding environment increased. When the AER was mixed in the cement mortar, its chloride content was higher than that of the cement matrix around it, which confirms the chloride ion adsorption capacity of the AER.

Adsorption of mercury ions from wastewater by a hyperbranched and multi-functionalized dendrimer modified mixed-oxides nanoparticles.

Science.gov (United States)

Arshadi, M; Mousavinia, F; Khalafi-Nezhad, A; Firouzabadi, H; Abbaspourrad, A

2017-11-01

In this paper, a novel heterogeneous nanodendrimer with generation of G2.0 was prepared by individual grafting of diethylenetriamine, triazine and l-cysteine methyl ester on the modified aluminum-silicate mixed oxides as a potent adsorbent of Hg(II) ions from aqueous media. The prepared nanodendrimer was characterized by nuclear magnetic resonance spectrum ( 1 H NMR and 13 C NMR), Fourier transform infrared spectroscopy (FT-IR), Diffuse reflectance UV-Vis spectroscopy (DR UV-Vis), zeta potential (ζ), inductively coupled plasma atomic emission spectroscopy (ICP-AES), transmission electron microscopy (TEM), scanning electron microscopy (SEM), nitrogen adsorption experiments at -196°C and elemental analysis. Equilibrium and kinetic models for Hg(II) ions removal were used by investigating the effect of the contact time, adsorbent dosage, initial Hg(II) ions concentrations, effect of solution's temperature, interfering ions, and initial pH. The contact time to approach equilibrium for higher removal was 6min (3232mgg -1 ). The removal of Hg(II) ions has been assessed in terms of pseudo-first- and -second-order kinetics, and the Freundlich, Langmuir and Sips isotherms models have also been applied to the equilibrium removal data. The removal kinetics followed the mechanism of the pseudo-second order equation, where the chemical sorption is the rate-limiting step of removal process and not involving mass transfer in solution, which was further proved by several techniques such as zeta potential, FT-IR and DS UV-vis. The thermodynamic parameters (ΔG, ΔH and ΔS) implied that the removal of mercury ions was feasible, spontaneous and chemically exothermic in nature between 15 and 80°C. The nanodendrimer indicated high reusability due to its high removal ability after 15 adsorption-desorption runs. The adsorption mechanisms of Hg(II) ions onto the nanodendrimer was further studied by diverse techniques such as FTIR, EDS, zeta potential, DR UV-Vis spectroscopy and SEM

Modification of cyanobacterial bloom-derived biomass using potassium permanganate enhanced the removal of microcystins and adsorption capacity toward cadmium (II)

Energy Technology Data Exchange (ETDEWEB)

Shao, Jihai [College of Resources and Environment, Hunan Agricultural University, Changsha 410128 (China); Hunan Provincial Key Laboratory of Farmland Pollution Control and Agricultural Resources Use, Hunan Agricultural University, Changsha 410128 (China); Gu, Ji-Dong [Hunan Provincial Key Laboratory of Farmland Pollution Control and Agricultural Resources Use, Hunan Agricultural University, Changsha 410128 (China); Laboratory of Environmental Microbiology and Toxicology, School of Biological Sciences, The University of Hong Kong, Hong Kong Special Administrative Region (Hong Kong); Peng, Liang; Luo, Si; Luo, Huili [College of Resources and Environment, Hunan Agricultural University, Changsha 410128 (China); Yan, Zhiyong, E-mail: zhyyan111@163.com [College of Resources and Environment, Hunan Agricultural University, Changsha 410128 (China); Wu, Genyi, E-mail: wugenyi99@163.com [College of Resources and Environment, Hunan Agricultural University, Changsha 410128 (China)

2014-05-01

Highlights: • Potassium permanganate removed microcystins in the cyanobacterial bloom-derived biomass (CBDB). • Potassium permanganate oxidation caused the transformation of hydroxyl to carboxyl on the CBDB. • Manganese dioxide was formed on the surface of CBDB. • Potassium permanganate oxidation process increased the adsorption capacity of CBDB toward Cd(II). - Abstract: Cyanobacterial biomass shows high adsorption capacity toward heavy metal ions. However, the cyanotoxins in the cyanobacterial biomass inhibit its application in heavy metals removal. In order to safely and effectively remove Cd(II) from water using cyanobacterial bloom-derived biomass (CBDB), KMnO{sub 4} was used to modify CBDB. The results indicated that the microcystins in the CBDB were successfully removed by KMnO{sub 4}. Potassium permanganate oxidation caused the transformation of hydroxyl to carboxyl on the CBDB, and formed manganese dioxide on the surface of CBDB. The oxidized CBDB showed higher adsorption capacity toward Cd(II) than that of unoxidized treatment. The optimal KMnO{sub 4} concentration for increasing the adsorption capacity of CBDB toward Cd(II) was 0.2 g/L. The adsorption isotherm of Cd(II) by oxidized- or unoxidized-CBDB was well fitted by Langmuir model, indicating that the adsorption of Cd(II) by CBDB was monolayer adsorption. The desorption ratio of Cd(II) from oxidized CBDB was higher than that from unoxidized CBDB in the desorption process using NH{sub 4}NO{sub 3} and EDTA as desorbent. The results presented in this study suggest that KMnO{sub 4} modified CBDB may be used as a safe and high efficient adsorbent in Cd(II) removal from water.

First principles study of elemental mercury (Hg0) adsorption on low index CoMnO3 surfaces

International Nuclear Information System (INIS)

Ji, Wenchao; Su, Pingru; Tang, Qingli; Cheng, Zhiwen; Shen, Zhemin; Fan, Maohong

2017-01-01

Highlights: • Hg 0 adsorption on low index CoMnO 3 surface was predicted by DFT method. • Hg 0 is adsorbed on the CoMnO 3 surface with chemisorption interaction. • Hg 0 has highest adsorption energy on CoMnO 3 (1 0 0) surface with Hg-Mn mechanism. • The electron transfer of Hg 0 has positive relationship with adsorption energy. - Abstract: The density functional theory (DFT) is applied to predict elemental mercury (Hg 0 ) adsorption on CoMnO 3 surface for the first time. GGA/PBE functional were selected to determine the potential Hg 0 capture mechanisms. The results show that Hg 0 has good affinity with CoMnO 3 surfaces with chemical adsorption. The adsorption energy of Hg 0 -CoMnO 3 (1 0 0), Hg 0 -CoMnO 3 (1 0 1) and Hg 0 -CoMnO 3 (1 1 0) are −85.225, −72.305 and −70.729 kJ/mol, respectively. The Hg-Mn and Hg-Co mechanisms were revealed on low index surfaces. Hg 0 was oxidized to its valence state of 0.236 on Mn site in CoMnO 3 (1 0 0) surface. The Hg-Co interaction mechanism occurred on Hg 0 -CoMnO 3 (1 0 1) and Hg 0 -CoMnO 3 (1 1 0) with 0.209e − and 0.189e − transformation, respectively. The PDOS analysis shows that Hg-Mn interaction depends on the hybridization of Hg(s- and d-orbitals) and Mn (s-, p- and d- orbitals). However, Hg-Co interaction stems from s- and d- orbitals of Hg, which only overlapping with d- and p- orbital of Co. Both the adsorption energy and electronic structure analysis indicated that CoMnO 3 catalyst performed excellent in Hg 0 oxidation. Exposing CoMnO 3 (1 0 0) is most favorable in Hg 0 control, which provides theoretical instruction on certain crystal plane synthesis in experiment.

Innate stimulatory capacity of high molecular weight transition metals Au (gold) and Hg (mercury).

Science.gov (United States)

Rachmawati, Dessy; Alsalem, Inás W A; Bontkes, Hetty J; Verstege, Marleen I; Gibbs, Sue; von Blomberg, B M E; Scheper, Rik J; van Hoogstraten, Ingrid M W

2015-03-01

Nickel, cobalt and palladium ions can induce an innate immune response by triggering Toll-like receptor (TLR)-4 which is present on dendritic cells (DC). Here we studied mechanisms of action for DC immunotoxicity to gold and mercury. Next to gold (Na3Au (S2O3)2⋅2H2O) and mercury (HgCl2), nickel (NiCl2) was included as a positive control. MoDC activation was assessed by release of the pro-inflammatory mediator IL-8. Also PBMC were studied, and THP-1 cells were used as a substitution for DC for evaluation of cytokines and chemokines, as well as phenotypic, alterations in response to gold and mercury. Our results showed that both Na3Au (S2O3)2⋅2H2O and HgCl2 induce substantial release of IL-8, but not IL-6, CCL2 or IL-10, from MoDc, PBMC, or THP-1 cells. Also gold and, to a lesser extent mercury, caused modest dendritic cell maturation as detected by increased membrane expression of CD40 and CD80. Both metals thus show innate immune response capacities, although to a lower extent than reported earlier for NiCl2, CoCl2 and Na2 [PdCl4]. Importantly, the gold-induced response could be ascribed to TLR3 rather than TLR4 triggering, whereas the nature of the innate mercury response remains to be clarified. In conclusion both gold and mercury can induce innate immune responses, which for gold could be ascribed to TLR3 dependent signalling. These responses are likely to contribute to adaptive immune responses to these metals, as reflected by skin and mucosal allergies. Copyright © 2014 Elsevier Ltd. All rights reserved.

Construction of horizontal stratum landform-like composite foams and their methyl orange adsorption capacity

International Nuclear Information System (INIS)

Chen, Jiajia; Shi, Xiaowen; Zhan, Yingfei; Qiu, Xiaodan; Du, Yumin; Deng, Hongbing

2017-01-01

Highlights: • CS/REC/CNTs composite foams were prepared by unidirectional freeze-casting. • Horizontal stratum landform-like structure was successful built up in foam. • The addition of REC and CNTs promoted the mechanical properties of foam. • The introduction of REC and CNTs enhanced the adsorption capacity of foam on dye. - Abstract: Chitosan (CS)/rectorite (REC)/carbon nanotubes (CNTs) composite foams with good mechanical properties were successfully fabricated by unidirectional freeze-casting technique. The morphology of the foam showed the well-ordered porous three-dimensional layers and horizontal stratum landform-like structure. The holes on the layers looked like the wings of butterfly. Additionally, the X-ray photoelectron spectroscopy and energy-dispersive X-ray spectroscopy results indicated the successful addition of CNTs and REC. The intercalated REC with CS chains was confirmed by small-angle X-ray diffraction. The surface structure of the foams was also analyzed by Raman spectroscopy. The adsorption experiments showed that when the mass ratio of CS to REC was 10:1 and CNTs content was 20%, the composite foam performed best in adsorbing low concentration methyl orange, and the largest adsorption capacity was 41.65 mg/g.

Construction of horizontal stratum landform-like composite foams and their methyl orange adsorption capacity

Energy Technology Data Exchange (ETDEWEB)

Chen, Jiajia; Shi, Xiaowen; Zhan, Yingfei; Qiu, Xiaodan; Du, Yumin; Deng, Hongbing, E-mail: hbdeng@whu.edu.cn

2017-03-01

Highlights: • CS/REC/CNTs composite foams were prepared by unidirectional freeze-casting. • Horizontal stratum landform-like structure was successful built up in foam. • The addition of REC and CNTs promoted the mechanical properties of foam. • The introduction of REC and CNTs enhanced the adsorption capacity of foam on dye. - Abstract: Chitosan (CS)/rectorite (REC)/carbon nanotubes (CNTs) composite foams with good mechanical properties were successfully fabricated by unidirectional freeze-casting technique. The morphology of the foam showed the well-ordered porous three-dimensional layers and horizontal stratum landform-like structure. The holes on the layers looked like the wings of butterfly. Additionally, the X-ray photoelectron spectroscopy and energy-dispersive X-ray spectroscopy results indicated the successful addition of CNTs and REC. The intercalated REC with CS chains was confirmed by small-angle X-ray diffraction. The surface structure of the foams was also analyzed by Raman spectroscopy. The adsorption experiments showed that when the mass ratio of CS to REC was 10:1 and CNTs content was 20%, the composite foam performed best in adsorbing low concentration methyl orange, and the largest adsorption capacity was 41.65 mg/g.

The influence of adsorption capacity on enhanced gas absorption in activated carbon slurries

NARCIS (Netherlands)

Holstvoogd, R.D.; van Swaaij, Willibrordus Petrus Maria

1990-01-01

The enhanced absorption of gases in aqueous activated carbbon slurries of fine particles is studied with a non-steady-state absorption model, taking into account the finite adsorption capacity of the carbon particles. It has been found that, for the different gas/activated carbon slurry systems

Effect of Nitrogen Oxides on Elemental Mercury Removal by Nanosized Mineral Sulfide.

Science.gov (United States)

Li, Hailong; Zhu, Lei; Wang, Jun; Li, Liqing; Lee, Po-Heng; Feng, Yong; Shih, Kaimin

2017-08-01

Because of its large surface area, nanosized zinc sulfide (Nano-ZnS) has been demonstrated in a previous study to be efficient for removal of elemental mercury (Hg 0 ) from coal combustion flue gas. The excellent mercury adsorption performance of Nano-ZnS was found to be insusceptible to water vapor, sulfur dioxide, and hydrogen chloride. However, nitrogen oxides (NO X ) apparently inhibited mercury removal by Nano-ZnS; this finding was unlike those of many studies on the promotional effect of NO X on Hg 0 removal by other sorbents. The negative effect of NO X on Hg 0 adsorption over Nano-ZnS was systematically investigated in this study. Two mechanisms were identified as primarily responsible for the inhibitive effect of NO X on Hg 0 adsorption over Nano-ZnS: (1) active sulfur sites on Nano-ZnS were oxidized to inactive sulfate by NO X ; and (2) the chemisorbed mercury, i.e., HgS, was reduced to Hg 0 by NO X . This new insight into the role of NO X in Hg 0 adsorption over Nano-ZnS can help to optimize operating conditions, maximize Hg 0 adsorption, and facilitate the application of Nano-ZnS as a superior alternative to activated carbon for Hg 0 removal using existing particulate matter control devices in power plants.

Study of the removal of mercury(II) and chromium(VI) from aqueous solutions by Moroccan stevensite

International Nuclear Information System (INIS)

Benhammou, A.; Yaacoubi, A.; Nibou, L.; Tanouti, B.

2005-01-01

The objective of the present study was to investigate the adsorption of the heavy metals mercury(II) and chromium(VI), from aqueous solutions, onto Moroccan stevensite. A mineralogical and physicochemical characterization of natural stevensite was carried out. In order to improve the adsorption capacity of stevensite for Cr(VI), a preparation of stevensite was carried out. It consists in saturating the stevensite by ferrous iron Fe(II) and reducing the total Fe by Na 2 S 2 O 4 . Then, the adsorption experiments were studied in batch reactors at 25 ± 3 deg. C. The influence of the pH solution on the Cr(VI) and Hg(II) adsorption was studied in the pH range of 1.5-7.0. The optimum pH for the Cr(VI) adsorption is in the pH range of 2.0-5.0 while that of Hg(II) is at the pH values above 4.0. The adsorption kinetics were tested by a pseudo-second-order model. The adsorption rate of Hg(II) is 54.35 mmol kg -1 min -1 and that of Cr(VI) is 7.21 mmol kg -1 min -1 . The adsorption equilibrium time for Hg(II) and Cr(VI) was reached within 2 and 12 h, respectively. The adsorption isotherms were described by the Dubinin-Radushkevich model. The maximal adsorption capacity for Cr(VI) increases from 13.7 (raw stevensite) to 48.86 mmol kg -1 (modified stevensite) while that of Hg(II) decreases from 205.8 to 166.9 mmol kg -1 . The mechanism of Hg(II) and Cr(VI) adsorption was discussed

High adsorptive γ-AlOOH(boehmite)@SiO2/Fe3O4 porous magnetic microspheres for detection of toxic metal ions in drinking water.

Science.gov (United States)

Wei, Yan; Yang, Ran; Zhang, Yong-Xing; Wang, Lun; Liu, Jin-Huai; Huang, Xing-Jiu

2011-10-21

γ-AlOOH(boehmite)@SiO(2)/Fe(3)O(4) porous magnetic microspheres with high adsorption capacity toward heavy metal ions were found to be useful for the simultaneous and selective electrochemical detection of five metal ions, such as ultratrace zinc(II), cadmium(II), lead(II), copper(II), and mercury(II), in drinking water.

Gas adsorption capacity in an all carbon nanomaterial composed of carbon nanohorns and vertically aligned carbon nanotubes.

Science.gov (United States)

Puthusseri, Divya; Babu, Deepu J; Okeil, Sherif; Schneider, Jörg J

2017-10-04

Whereas vertically aligned carbon nanotubes (VACNTs) typically show a promising adsorption behavior at high pressures, carbon nanohorns (CNHs) exhibit superior gas adsorption properties in the low pressure regime due to their inherent microporosity. These adsorption characteristics are further enhanced when both materials are opened at their tips. The so prepared composite material allows one to investigate the effect of physical entrapment of CO 2 molecules within the specific adsorption sites of VACNTs composed of opened double walled carbon nanotubes (CNTs) and in specific adsorption sites created by spherically aggregated opened single walled carbon nanohorns. Combining 50 wt% of tip opened CNTs with tip opened CNHs increases the CO 2 adsorption capacity of this material by ∼24% at 30 bar and 298 K compared to opened CNHs alone.

Mercury removal from solution by superconducting magnetic separation with nanostructured magnetic adsorbents

Energy Technology Data Exchange (ETDEWEB)

Okamoto, T., E-mail: okamoto-takayuki@ed.tmu.ac.jp [Graduate School of Science and Engineering, Tokyo Metropolitan University, 1-1 Minami-Osawa, Hachioji, Tokyo 192-0397 (Japan); Tachibana, S.; Miura, O. [Graduate School of Science and Engineering, Tokyo Metropolitan University, 1-1 Minami-Osawa, Hachioji, Tokyo 192-0397 (Japan); Takeuchi, M. [Komazawa Jin Clinic, 1-19-8 Komazawa, Setagayaku, Tokyo 154-0012 (Japan)

2011-11-15

Recently, mercury Hg concentration in human blood increases due to expanding the global mercury contamination. Excess mercury bioaccumulation poses a significant health risk. In order to decrease mercury concentration in the environment and human blood, we have developed two different kinds of nanostructured magnetic adsorbents for mercury to apply them to superconducting magnetic separation instead of conventional filtration. One is magnetic beads (MBs) which have nanosize magnetite particles in the core and a lot of SH radicals on the surface to adsorb Hg ions effectively. MBs were developed mainly to remove mercury from human blood. The maximum amount of the adsorption for MBs is 6.3 mg/g in the solution in less than a minute. Dithiothreitol can easily remove mercury adsorbed to MBs, hence MBs can be reusable. The other is nanostructured magnetic activated carbon (MAC) which is activated carbon with mesopores and nanosize magnetite. The maximum amount of the adsorption for MAC is 38.3 mg/g in the solution. By heat-treatment mercury can be easily removed from MAC. We have studied superconducting magnetic separation using each adsorbent for mercury removal from solution.

Comparative study of carbon nanotubes and granular activated carbon: Physicochemical properties and adsorption capacities.

Science.gov (United States)

Gangupomu, Roja Haritha; Sattler, Melanie L; Ramirez, David

2016-01-25

The overall goal was to determine an optimum pre-treatment condition for carbon nanotubes (CNTs) to facilitate air pollutant adsorption. Various combinations of heat and chemical pre-treatment were explored, and toluene was tested as an example hazardous air pollutant adsorbate. Specific objectives were (1) to characterize raw and pre-treated single-wall (SW) and multi-wall (MW) CNTs and compare their physical/chemical properties to commercially available granular activated carbon (GAC), (2) to determine the adsorption capacities for toluene onto pre-treated CNTs vs. GAC. CNTs were purified via heat-treatment at 400 °C in steam, followed by nitric acid treatment (3N, 5N, 11N, 16N) for 3-12 h to create openings to facilitate adsorption onto interior CNT sites. For SWNT, Raman spectroscopy showed that acid treatment removed impurities up to a point, but amorphous carbon reformed with 10h-6N acid treatment. Surface area of SWNTs with 3 h-3N acid treatment (1347 m(2)/g) was higher than the raw sample (1136 m(2)/g), and their toluene maximum adsorption capacity was comparable to GAC. When bed effluent reached 10% of inlet concentration (breakthrough indicating time for bed cleaning), SWNTs had adsorbed 240 mg/g of toluene, compared to 150 mg/g for GAC. Physical/chemical analyses showed no substantial difference for pre-treated vs. raw MWNTs. Copyright © 2015 Elsevier B.V. All rights reserved.

LabVIEW-based sequential-injection analysis system for the determination of trace metals by square-wave anodic and adsorptive stripping voltammetry on mercury-film electrodes.

Science.gov (United States)

Economou, Anastasios; Voulgaropoulos, Anastasios

2003-01-01

The development of a dedicated automated sequential-injection analysis apparatus for anodic stripping voltammetry (ASV) and adsorptive stripping voltammetry (AdSV) is reported. The instrument comprised a peristaltic pump, a multiposition selector valve and a home-made potentiostat and used a mercury-film electrode as the working electrodes in a thin-layer electrochemical detector. Programming of the experimental sequence was performed in LabVIEW 5.1. The sequence of operations included formation of the mercury film, electrolytic or adsorptive accumulation of the analyte on the electrode surface, recording of the voltammetric current-potential response, and cleaning of the electrode. The stripping step was carried out by applying a square-wave (SW) potential-time excitation signal to the working electrode. The instrument allowed unattended operation since multiple-step sequences could be readily implemented through the purpose-built software. The utility of the analyser was tested for the determination of copper(II), cadmium(II), lead(II) and zinc(II) by SWASV and of nickel(II), cobalt(II) and uranium(VI) by SWAdSV.

Preparation and properties of chitosan-metal complex: Some factors influencing the adsorption capacity for dyes in aqueous solution.

Science.gov (United States)

Rashid, Sadia; Shen, Chensi; Yang, Jing; Liu, Jianshe; Li, Jing

2018-04-01

Chitosan-metal complexes have been widely studied in wastewater treatment, but there are still various factors in complex preparation which are collectively responsible for improving the adsorption capacity need to be further studied. Thus, this study investigates the factors affecting the adsorption ability of chitosan-metal complex adsorbents, including various kinds of metal centers, different metal salts and crosslinking degree. The results show that the chitosan-Fe(III) complex prepared by sulfate salts exhibited the best adsorption efficiency (100%) for various dyes in very short time duration (10min), and its maximum adsorption capacity achieved 349.22mg/g. The anion of the metal salt which was used in preparation played an important role to enhance the adsorption ability of chitosan-metal complex. SO 4 2- ions not only had the effect of crosslinking through electrostatic interaction with amine group of chitosan polymer, but also could facilitate the chelation of metal ions with chitosan polymer during the synthesis process. Additionally, the pH sensitivity and the sensitivity of ionic environment for chitosan-metal complex were analyzed. We hope that these factors affecting the adsorption of the chitosan-metal complex can help not only in optimizing its use but also in designing new chitosan-metal based complexes. Copyright © 2017. Published by Elsevier B.V.

Foam-based adsorbents having high adsorption capacities for recovering dissolved metals and methods thereof

Science.gov (United States)

Janke, Christopher J.; Dai, Sheng; Oyola, Yatsandra

2015-06-02

Foam-based adsorbents and a related method of manufacture are provided. The foam-based adsorbents include polymer foam with grafted side chains and an increased surface area per unit weight to increase the adsorption of dissolved metals, for example uranium, from aqueous solutions. A method for forming the foam-based adsorbents includes irradiating polymer foam, grafting with polymerizable reactive monomers, reacting with hydroxylamine, and conditioning with an alkaline solution. Foam-based adsorbents formed according to the present method demonstrated a significantly improved uranium adsorption capacity per unit weight over existing adsorbents.

Biosorption of mercury by capsulated and slime layerforming Gram ...

African Journals Online (AJOL)

The biosorption of mercury by two locally isolated Gram-ve bacilli: Klebsiella pneumoniae ssp. pneumonia (capsulated) and slime layer forming Pseudomonas aeruginosa, was characterized. Mercury adsorption was found to be influenced by the pH value of the biosorption solution, initial metal concentration, amount of the ...

Engineering and characterization of mesoporous silica-coated magnetic particles for mercury removal from industrial effluents

International Nuclear Information System (INIS)

Dong Jie; Xu Zhenghe; Wang Feng

2008-01-01

Mesoporous silica coatings were synthesized on dense liquid silica-coated magnetite particles using cetyl-trimethyl-ammonium chloride (CTAC) as molecular templates, followed by sol-gel process. A specific surface area of the synthesized particles as high as 150 m 2 /g was obtained. After functionalization with mercapto-propyl-trimethoxy-silane (MPTS) through silanation reaction, the particles exhibited high affinity of mercury in aqueous solutions. Atomic force microscopy (AFM), zeta potential measurement, thermal gravimetric analysis (TGA), analytical transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and atomic absorption spectroscopy (AAS) were used to characterize the synthesis processes, surface functionalization, and mercury adsorption on the synthesized magnetite particles. The loading capacity of the particles for mercury was determined to be as high as 14 mg/g at pH 2. A unique feature of strong magnetism of the synthesized nanocomposite particles makes the subsequent separation of the magnetic sorbents from complex multiphase suspensions convenient and effective

Engineering and characterization of mesoporous silica-coated magnetic particles for mercury removal from industrial effluents

Science.gov (United States)

Dong, Jie; Xu, Zhenghe; Wang, Feng

2008-03-01

Mesoporous silica coatings were synthesized on dense liquid silica-coated magnetite particles using cetyl-trimethyl-ammonium chloride (CTAC) as molecular templates, followed by sol-gel process. A specific surface area of the synthesized particles as high as 150 m 2/g was obtained. After functionalization with mercapto-propyl-trimethoxy-silane (MPTS) through silanation reaction, the particles exhibited high affinity of mercury in aqueous solutions. Atomic force microscopy (AFM), zeta potential measurement, thermal gravimetric analysis (TGA), analytical transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and atomic absorption spectroscopy (AAS) were used to characterize the synthesis processes, surface functionalization, and mercury adsorption on the synthesized magnetite particles. The loading capacity of the particles for mercury was determined to be as high as 14 mg/g at pH 2. A unique feature of strong magnetism of the synthesized nanocomposite particles makes the subsequent separation of the magnetic sorbents from complex multiphase suspensions convenient and effective.

Oil Spill Adsorption Capacity of Activated Carbon Tablets from Corncobs in Simulated Oil-Water Mixture

Directory of Open Access Journals (Sweden)

Rhonalyn V. Maulion

2015-12-01

Full Text Available Oil spill in bodies of water is one of severe environmental problems that is facing all over the country and in the world. Since oil is an integral part of the economy, increasing trend for its demand and transport of has led to a great treat in the surface water. One of the promising techniques in the removal of the oil spills in water bodies is adsorption using activated carbon form waste material such as corn cobs. The purpose of this study is to determine the adsorption capacity of activated carbon tablets derived from corncobs in the removal of oil. The properties of activated carbon produced have a pH of 7.0, bulk density of 0.26 g//cm3 , average pore size of 45nm, particle size of 18% at 60 mesh and 39% at 80 mesh, iodine number of 1370 mg/g and surface area of 1205 g/m2. The amount of bentonite clay as binder (15%,20%,30%, number of ACT (1,2,3 and time of contact(30,60,90 mins has been varied to determine the optimum condition where the activated carbon will have the best adsorption capacity in the removal of oil. Results showed that at 15% binder, 60 mins contact time and 3 tablets of activated carbon is the optimum condition which give a percentage adsorption of 22.82% of oil. Experimental data also showed that a Langmuir isotherm was the best fit isotherm for adsorption of ACT.

Influence of the inherent properties of drinking water treatment residuals on their phosphorus adsorption capacities.

Science.gov (United States)

Bai, Leilei; Wang, Changhui; He, Liansheng; Pei, Yuansheng

2014-12-01

Batch experiments were conducted to investigate the phosphorus (P) adsorption and desorption on five drinking water treatment residuals (WTRs) collected from different regions in China. The physical and chemical characteristics of the five WTRs were determined. Combined with rotated principal component analysis, multiple regression analysis was used to analyze the relationship between the inherent properties of the WTRs and their P adsorption capacities. The results showed that the maximum P adsorption capacities of the five WTRs calculated using the Langmuir isotherm ranged from 4.17 to 8.20mg/g at a pH of 7 and further increased with a decrease in pH. The statistical analysis revealed that a factor related to Al and 200 mmol/L oxalate-extractable Al (Alox) accounted for 36.5% of the variations in the P adsorption. A similar portion (28.5%) was attributed to an integrated factor related to the pH, Fe, 200 mmol/L oxalate-extractable Fe (Feox), surface area and organic matter (OM) of the WTRs. However, factors related to other properties (Ca, P and 5 mmol/L oxalate-extractable Fe and Al) were rejected. In addition, the quantity of P desorption was limited and had a significant negative correlation with the (Feox+Alox) of the WTRs (p<0.05). Overall, WTRs with high contents of Alox, Feox and OM as well as large surface areas were proposed to be the best choice for P adsorption in practical applications. Copyright © 2014. Published by Elsevier B.V.

Removal of mercury from water using pottery

International Nuclear Information System (INIS)

Helal, A.A.A.

2006-01-01

In a previous study, the sorption of radiocobalt by powdered pottery materials was investigated. The use of these materials as immobilization matrix for liquid radioactive waste requires the employment of pottery vessels. Therefore, the present study aims to give detailed investigations of the decontamination of radionuclides and toxic elements using pottery containers. These investigations are equally useful to elucidate how far these vessels can be utilized for water purification through decontamination of toxic and heavy metals. The radionuclide or heavy metal removal capability using pottery pots, as low cost sorbents, has been investigated for both radioactive ( 203 Hg) and stable mercury. The results indicated that Hg 2+ is better removed by pottery from neutral to alkaline solutions. The capacity of the used pottery container (100 ml in volume) for complete removal of mercury was found to reach 3 x 10 -4 mol/l, and the time needed was 8 hours. The sorption process was suggested to occur via adsorption and ion exchange. The effect of presence of humic or fulvic acid, as ligands abundant in water, is also investigated. The results imply that, in absence of humic or fulvic acid the sorption follows the expected behaviour, i.e. sorption sites with similar affinity for mercury. In presence of humic or fulvic acid, additional sorption sites are available by the organic molecule when it is associated to the pottery. (orig.)

Thief process for the removal of mercury from flue gas

Science.gov (United States)

Pennline, Henry W.; Granite, Evan J.; Freeman, Mark C.; Hargis, Richard A.; O'Dowd, William J.

2003-02-18

A system and method for removing mercury from the flue gas of a coal-fired power plant is described. Mercury removal is by adsorption onto a thermally activated sorbent produced in-situ at the power plant. To obtain the thermally activated sorbent, a lance (thief) is inserted into a location within the combustion zone of the combustion chamber and extracts a mixture of semi-combusted coal and gas. The semi-combusted coal has adsorptive properties suitable for the removal of elemental and oxidized mercury. The mixture of semi-combusted coal and gas is separated into a stream of gas and semi-combusted coal that has been converted to a stream of thermally activated sorbent. The separated stream of gas is recycled to the combustion chamber. The thermally activated sorbent is injected into the duct work of the power plant at a location downstream from the exit port of the combustion chamber. Mercury within the flue gas contacts and adsorbs onto the thermally activated sorbent. The sorbent-mercury combination is removed from the plant by a particulate collection system.

Effects of textural and surface characteristics of microporous activated carbons on the methane adsorption capacity at high pressures

International Nuclear Information System (INIS)

Bastos-Neto, M.; Canabrava, D.V.; Torres, A.E.B.; Rodriguez-Castellon, E.; Jimenez-Lopez, A.; Azevedo, D.C.S.; Cavalcante, C.L.

2007-01-01

The objective of this study is to relate textural and surface characteristics of selected microporous activated carbons to their methane storage capacity. In this work, a magnetic suspension balance (Rubotherm, Germany) was used to measure methane adsorption isotherms of several activated carbon samples. Textural characteristics were assessed by nitrogen adsorption on a regular surface area analyzer (Autosorb-MP, by Quantachrome, USA). N 2 adsorption was analysed by conventional models (BET, DR, HK) and by Monte Carlo molecular simulations. Elemental and surface analyses were performed by X-ray photoelectronic spectroscopy (XPS) for the selected samples. A comparative analysis was then carried out with the purpose of defining some correlation among the variables under study. For the system under study, pore size distribution and micropore volume seem to be a determining factor as long as the solid surface is perfectly hydrophobic. It was concluded that the textural parameters per se do not unequivocally determine natural gas storage capacities. Surface chemistry and methane adsorption equilibria must be taken into account in the decision-making process of choosing an adsorbent for gas storage

Effect of carbonation temperature on CO{sub 2} adsorption capacity of CaO derived from micro/nanostructured aragonite CaCO{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Hlaing, Nwe Ni, E-mail: nwenihlaing76@gmail.com [School of Materials and Mineral Resources Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang (Malaysia); Department of International Development Engineering, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo (Japan); Department of Physics, University of Yangon, 11041 Kamayut, Yangon (Myanmar); Sreekantan, Srimala, E-mail: srimala@usm.my [School of Materials and Mineral Resources Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang (Malaysia); Hinode, Hirofumi, E-mail: hinode@ide.titech.ac.jp; Kurniawan, Winarto, E-mail: Kurniawan.w.ab@m.titech.ac.jp [Department of International Development Engineering, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo (Japan); Thant, Aye Aye, E-mail: a2thant@gmail.com [Department of Physics, University of Yangon, 11041 Kamayut, Yangon (Myanmar); Othman, Radzali, E-mail: radzali@utem.edu.my [Faculty of Manufacturing Engineering, Universiti Teknikal Malaysia Melaka, Hang Tuah Jaya, 76100 Durian Tunggal, Malacca (Malaysia); Mohamed, Abdul Rahman, E-mail: chrahman@eng.usm.my [Low Carbon Economy (LCE) Research Group, School of Chemical Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang (Malaysia); Salime, Chris, E-mail: chris.salim@surya.ac.id [Environmental Engineering, Surya University, Tangerang, 15810 Banten (Indonesia)

2016-07-06

Recent years, CaO-based synthetic materials have been attracted attention as potential adsorbents for CO{sub 2} capture mainly due to their high CO{sub 2} adsorption capacity. In this study, micro/nanostructured aragonite CaCO{sub 3} was synthesized by a simple hydrothermal method with using polyacrylamide (PAM). The structural, morphological and thermal properties of the synthesized sample were investigated by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM) and thermogravimetry analysis (TG-DTA). The XRD and FESEM results showed that the obtained sample was aragonite CaCO{sub 3} with aggregated nanorods and microspheres composed of nanorods. A TG-DTA apparatus with Thermoplus 2 software was used to investigate the effect of carbonation temperature on the CO{sub 2} adsorption capacity of CaO derived from aragonite CaCO{sub 3} sample. At 300 °C, the sample reached the CO{sub 2} adsorption capacity of 0.098 g-CO{sub 2}/g-adsorbent, whereas the sample achieved the highest capacity of 0.682 g-CO{sub 2}/g-adsorbent at 700 °C. The results showed that the carbonation temperature significantly influenced on the CO{sub 2} adsorption capacity of the CaO derived from aragonite CaCO{sub 3}.

Sampling problems and the determination of mercury in surface water, seawater, and air

International Nuclear Information System (INIS)

Das, H.A.; van der Sloot, H.A.

1976-01-01

Analysis of surface water for mercury comprises the determination of both ionic and organically bound mercury in solution and that of the total mercury content of the suspended matter. Eventually, metallic mercury has to be determined too. Requirements for the sampling procedure are given. A method for the routine determination of mercury in surface water and seawater was developed and applied to Dutch surface waters. The total sample volume is 2500 ml. About 500 ml is used for the determination of the content of suspended matter and the total amount of mercury in the water. The sample is filtered through a bed of previously purified active charcoal at a low flow-rate. The main portion ca. 2000 ml) passes a flow-through centrifuge to separate the solid fraction. One liter is used to separate ''inorganic'' mercury by reduction, volatilization in an airstream and adsorption on active charcoal. The other liter is led through a column of active charcoal to collect all mercury. The procedures were checked with 197 Hg radiotracer both as an ion and incorporated in organic compounds. The mercury is determined by thermal neutron activation, followed by volatilization in a tube furnace and adsorption on a fresh carbon bed. The limit of determination is approximately equal to 1 ng 1 -1 . The rate of desorption from and adsorption on suspended material has been measured as a function of a pH of the solution for Hg +2 and various other ions. It can be concluded that only the procedure mentioned above does not disturb the equilibrium. The separation of mercury from air is obtained by suction of 1 m 3 through a 0.22 μm filter and a charcoal bed. The determination is then performed as in the case of the water samples

Mercury release from deforested soils triggered by base cation enrichment

International Nuclear Information System (INIS)

Farella, N.; Lucotte, M.; Davidson, R.; Daigle, S.

2006-01-01

The Brazilian Amazon has experienced considerable colonization in the last few decades. Family agriculture based on slash-and-burn enables millions of people to live in that region. However, the poor nutrient content of most Amazonian soils requires cation-rich ashes from the burning of the vegetation biomass for cultivation to be successful, which leads to forest ecosystem degradation, soil erosion and mercury contamination. While recent studies have suggested that mercury present in soils was transferred towards rivers upon deforestation, little is known about the dynamics between agricultural land-use and mercury leaching. In this context, the present study proposes an explanation that illustrates how agricultural land-use triggers mercury loss from soils. This explanation lies in the competition between base cations and mercury in soils which are characterized by a low adsorption capacity. Since these soils are naturally very poor in base cations, the burning of the forest biomass suddenly brings high quantities of base cations to soils, destabilizing the previous equilibrium amongst cations. Base cation enrichment triggers mobility in soil cations, rapidly dislocating mercury atoms. This conclusion comes from principal component analyses illustrating that agricultural land-use was associated with base cation enrichment and mercury depletion. The overall conclusions highlight a pernicious cycle: while soil nutrient enrichment actually occurs through biomass burning, although on a temporary basis, there is a loss in Hg content, which is leached to rivers, entering the aquatic chain, and posing a potential health threat to local populations. Data presented here reflects three decades of deforestation activities, but little is known about the long-term impact of such a disequilibrium. These findings may have repercussions on our understanding of the complex dynamics of deforestation and agriculture worldwide

Effect of degree of deacetylation of chitosan on adsorption capacity and reusability of chitosan/polyvinyl alcohol/TiO2 nano composite.

Science.gov (United States)

Habiba, Umma; Joo, Tan Chin; Siddique, Tawsif A; Salleh, Areisman; Ang, Bee Chin; Afifi, Amalina M

2017-11-01

The chitosan/polyvinyl alcohol/TiO 2 composite was synthesized. Two different degrees of deacetylation of chitosan were prepared by hydrolysis to compare the effectiveness of them. The composite was analyzed via field emission scanning electron microscopy, Fourier transform infrared, X-ray diffraction, thermal gravimetric analysis, weight loss test and adsorption study. The FTIR and XRD results proved the interaction among chitosan, PVA and TiO 2 without any chemical reaction. It was found that, chitosan with higher degree of deacetylation has better stability. Furthermore, it also showed that higher DD of chitosan required less time to reach equilibrium for methyl orange. The adsorption followed the pseudo-second-order kinetic model. The Langmuir and Freundlich isotherm models were fitted well for isotherm study. Adsorption capacity was higher for the composite containing chitosan with higher DD. The dye removal rate was independent of the dye's initial concentration. The adsorption capacity was increased with temperature and it was found from reusability test that the composite containing chitosan with higher DD is more reusable. It was notable that adsorption capacity was even after 15 runs. Therefore, chitosan/PVA/TiO 2 composite can be a very useful material for dye removal. Copyright © 2017 Elsevier B.V. All rights reserved.

Langmuir and Freundlich Isotherm Adsorption Equations for Chromium (VI) Waste Adsorption by Zeolite

International Nuclear Information System (INIS)

Murni Handayani; Eko Sulistiyono

2009-01-01

The research of chromium (VI) waste adsorption by zeolite has done. Wastes which are produced by Industries, both radioactive waste and heavy metal waste need done more processing so that they are not endanger environment and human health. Zeolite has very well-ordered crystal form with cavity each other to way entirely so that cause surface wide of zeolite become very big and very good as adsorbents. This research intends to know appropriate isotherm adsorption method to determine maximum capacity of zeolite to chromium (VI) waste. The equations which used in adsorption process are Langmuir and Freundlich isotherm Adsorption equations. The instrument was used in adsorption process by using Atomic Adsorption Spectroscopy (AAS). The experiment result showed that the biggest mass of chromium (VI) metal ion which was absorb by zeolite in 20 ppm concentration was 7.71 mg/gram zeolite. Adsorption process of Chromium (VI) waste by zeolite followed Langmuir and Freundlich isotherm equations with R 2 >0,9 . Appropriate equation to determine maximum adsorption capacity of zeolite for chromium (VI) waste adsorption is Langmuir equation. The maximum adsorption capacity of zeolite is 52.25 mg/gram. (author)

Polanyi Evaluation of Adsorptive Capacities of Commercial Activated Carbons

Science.gov (United States)

Monje, Oscar; Surma, Jan M.

2017-01-01

Commercial activated carbons from Calgon (207C and OVC) and Cabot Norit (RB2 and GCA 48) were evaluated for use in spacecraft trace contaminant control filters. The Polanyi potential plots of the activated carbons were compared using to those of Barnebey-Cheney Type BD, an untreated activated carbon with similar properties as the acid-treated Barnebey-Sutcliffe Type 3032 utilized in the TCCS. Their adsorptive capacities under dry conditions were measured in a closed loop system and the sorbents were ranked for their ability to remove common VOCs found in spacecraft cabin air. This comparison suggests that these sorbents can be ranked as GCA 48 207C, OVC RB2 for the compounds evaluated.

Studies on adsorption capacity of clay-Sargassum sp biosorbent for Cr (VI) removal in wastewater from electroplating industry

Science.gov (United States)

Aprianti, Tine; Aprilyanti, Selvia; Apriani, Rachmawati; Sisnayati

2017-11-01

Various raw biosorbents have been studied for pollutant treatment of heavy metals contained in wastewater. In this study, clay and brown seaweed, Sargassum sp, are used for hexavalent chromium [Cr (VI)] biosorption. The adsorption capacity is adequately improved by combining clay and Sargassum sp as the adsorbent agent. Ion exchange of metal ions has shown strong coordination cross-linkage due to organic functional hydroxyl groups (OH-) contained in brown seaweed that provide sites to capture and bind the metal ions. Clay is known as an inexpensive adsorbent due to its wide availability besides its large specific surface area. Combining clay and Sargassum sp as biosorbent resulting better adsorption, the adsorption capacity reaches most favorable results of 99.39% at Sargassum: clay ratio of 40:60 on contact time 10 h. This study has proven that composit biosorbent used has succeeded in reducing hexavalent chromium pollutant in wastewater.

Effect of the both texture and electrical properties of activated carbon on the CO{sub 2} adsorption capacity

Energy Technology Data Exchange (ETDEWEB)

Djeridi, W. [Research Laboratory: Engineering Process and Industrial Systems, National school of Engineers of Gabes, University of Gabes, St Omar Ibn Elkhattab, 6029 Gabes (Tunisia); Chimistry laboratory of Provence, University Aix-Marseille I, II, III- CNRS, UMR 6264, Centre de Saint Jerome, 13397 Marseille (France); Ouederni, A. [Research Laboratory: Engineering Process and Industrial Systems, National school of Engineers of Gabes, University of Gabes, St Omar Ibn Elkhattab, 6029 Gabes (Tunisia); Mansour, N.Ben [National Nanotechnology Research Centre, KACST, Riyadh (Saudi Arabia); Llewellyn, P.L. [Chimistry laboratory of Provence, University Aix-Marseille I, II, III- CNRS, UMR 6264, Centre de Saint Jerome, 13397 Marseille (France); Alyamani, A. [National Nanotechnology Research Centre, KACST, Riyadh (Saudi Arabia); El Mir, L., E-mail: djeridiwahid@yahoo.fr [Laboratory of Physics of Materials and Nanomaterials Applied at Environment (LaPhyMNE), Gabes University, Faculty of Sciences in Gabes, Gabes (Tunisia); Al Imam Mohammad Ibn Saud Islamic University (IMSIU), College of Sciences, Department of Physics, 11623 Riyadh (Saudi Arabia)

2016-01-15

Highlights: • A series of activated carbon pellet without binder was prepared by chemical activation. • Carbon dioxide storage isotherm at 30 °C and up to 25 bars was measured for the microporous carbon. • Adsorption enthalpies have been correlated with the carbon dioxide uptake. • Pyrolysis temperature effect on the electrical conductivity of the samples. • Impact of the both texture and electrical properties on CO{sub 2} adsorption capacity have been deducted - Abstract: A series of activated carbon pellets (ACP) based on olive stones were studied for CO{sub 2} storage application. The surface area, pore volume, and pore diameter were evaluated from the analysis of N{sub 2} adsorption isotherm data. The characterization of carbon materials was performed by scanning electron microscopy (SEM), the powder X-ray diffraction (PXRD) and transmission electron microscopy (TEM). The adsorption enthalpies were obtained by microcalorimetry. The effect of pyrolysis temperature on textural, electrical conductivity and gas adsorption capacities of the ACP were investigated by adsorbing CO{sub 2} at 303 K in the pressure range of 0–2.3 MPa. In fact the electrical conductivity is strongly affected by the microporosity of the samples and the size of the micropore. It increases when the pore size decreases which affect the CO{sub 2} adsorption. Also with increases temperature the free electrons concentration on the surface increases which affect the interaction of the adsorbed gas molecules.

Summary of Adsorption Capacity and Adsorption Kinetics of Uranium and Other Elements on Amidoxime-based Adsorbents from Time Series Marine Testing at the Pacific Northwest National Laboratory

International Nuclear Information System (INIS)

Gill, Gary A.; Das, Sadananda; Mayes, Richard; Saito, Tomonori; Brown, Suree S.; Tsouris, Constantinos; Tsouris, Costas; Wai, Chien M.; Pan, Horng-Bin

2016-01-01

The Pacific Northwest National Laboratory (PNNL) has been conducting marine testing of uranium adsorbent materials for the Fuel Resources Program, Department of Energy, Office of Nuclear Energy (DOE-NE) beginning in FY 2012. The marine testing program is being conducted at PNNL's Marine Sciences Laboratory (MSL), located at Sequim Bay, along the coast of Washington. One of the main efforts of the marine testing program is the determination of adsorption capacity and adsorption kinetics for uranium and selected other elements (e.g. vanadium, iron, copper, nickel, and zinc) for adsorbent materials provided primarily by Oak Ridge National Laboratory (ORNL), but also includes other Fuel Resources Program participants. This report summarizes the major marine testing results that have been obtained to date using time series sampling for 42 to 56 days using either flow-through column or recirculating flume exposures. The major results are highlighted in this report, and the full data sets are appended as a series of Excel spreadsheet files. Over the four year period (2012-2016) that marine testing of amidoxime-based polymeric adsorbents was conducted at PNNL's Marine Science Laboratory, there has been a steady progression of improvement in the 56-day adsorbent capacity from 3.30 g U/kg adsorbent for the ORNL 38H adsorbent to the current best performing adsorbent prepared by a collaboration between the University of Tennessee and ORNL to produce the adsorbent SB12-8, which has an adsorption capacity of 6.56 g U/kg adsorbent. This nearly doubling of the adsorption capacity in four years is a significant advancement in amidoxime-based adsorbent technology and a significant achievement for the Uranium from Seawater program. The achievements are evident when compared to the several decades of work conducted by the Japanese scientists beginning in the 1980's (Kim et al., 2013). The best adsorbent capacity reported by the Japanese scientists was 3.2 g U/kg adsorbent for a 180

Summary of Adsorption Capacity and Adsorption Kinetics of Uranium and Other Elements on Amidoxime-based Adsorbents from Time Series Marine Testing at the Pacific Northwest National Laboratory

Energy Technology Data Exchange (ETDEWEB)

Gill, Gary A. [Pacific Northwest National Lab. (PNNL), Sequim, WA (United States). Marine Sciences Lab.; Kuo, Li-Jung [Pacific Northwest National Lab. (PNNL), Sequim, WA (United States). Marine Sciences Lab.; Strivens, Jonathan E. [Pacific Northwest National Lab. (PNNL), Sequim, WA (United States). Marine Sciences Lab.; Wood, Jordana R. [Pacific Northwest National Lab. (PNNL), Sequim, WA (United States). Marine Sciences Lab.; Schlafer, Nicholas J. [Pacific Northwest National Lab. (PNNL), Sequim, WA (United States). Marine Sciences Lab.; Janke, Christopher J. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Das, Sadananda [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Mayes, Richard [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Saito, Tomonori [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Brown, Suree S. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Tsouris, Constantinos [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Tsouris, Costas [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Wai, Chien M. [Univ. of Idaho, Moscow, ID (United States); LCW Supercritical Technologies, Seattle, WA (United States); Pan, Horng-Bin [Univ. of Idaho, Moscow, ID (United States)

2016-09-29

The Pacific Northwest National Laboratory (PNNL) has been conducting marine testing of uranium adsorbent materials for the Fuel Resources Program, Department of Energy, Office of Nuclear Energy (DOE-NE) beginning in FY 2012. The marine testing program is being conducted at PNNL’s Marine Sciences Laboratory (MSL), located at Sequim Bay, along the coast of Washington. One of the main efforts of the marine testing program is the determination of adsorption capacity and adsorption kinetics for uranium and selected other elements (e.g. vanadium, iron, copper, nickel, and zinc) for adsorbent materials provided primarily by Oak Ridge National Laboratory (ORNL), but also includes other Fuel Resources Program participants. This report summarizes the major marine testing results that have been obtained to date using time series sampling for 42 to 56 days using either flow-through column or recirculating flume exposures. The major results are highlighted in this report, and the full data sets are appended as a series of Excel spreadsheet files. Over the four year period (2012-2016) that marine testing of amidoxime-based polymeric adsorbents was conducted at PNNL’s Marine Science Laboratory, there has been a steady progression of improvement in the 56-day adsorbent capacity from 3.30 g U/kg adsorbent for the ORNL 38H adsorbent to the current best performing adsorbent prepared by a collaboration between the University of Tennessee and ORNL to produce the adsorbent SB12-8, which has an adsorption capacity of 6.56 g U/kg adsorbent. This nearly doubling of the adsorption capacity in four years is a significant advancement in amidoxime-based adsorbent technology and a significant achievement for the Uranium from Seawater program. The achievements are evident when compared to the several decades of work conducted by the Japanese scientists beginning in the 1980’s (Kim et al., 2013). The best adsorbent capacity reported by the Japanese scientists was 3.2 g U/kg adsorbent for a

Theoretical prediction the removal of mercury from flue gas by MOFs

KAUST Repository

Liu, Yang; Li, Hailong; Liu, Jing

2016-01-01

Removal of mercury from flue gas has been considered as one of the hot topics in both the scientific and industrial world. Adsorption of elemental mercury (Hg) and oxidized mercury species (HgCl, HgO, and HgS) on a novel metal organic framework (MOF) material, named Mg/DOBDC, with unsaturated metal centers was investigated using density functional theory (DFT) calculations. The results show that Hg stably physi-sorbed on the unsaturated metal center (magnesium ion) of Mg/DOBDC with a binding energy (BE) of −27.5 kJ/mol. A direct interaction between Hg and magnesium ion was revealed by the partial density of state (PDOS) analysis. HgCl multi-interacts with two neighboring magnesium ions simultaneously by its Cl endings and thus resulted in strong adsorption strength (−89.0 kJ/mol). The adsorption energies of HgO and HgS on the Mg/DOBDC were as high as −117.0 kJ/mol and −169.7 kJ/mol, respectively, indicating a strong chemisorption. Theoretical calculations in this study reveal that Mg/DOBDC has the potential to serve as an efficient material for removal of mercury from flue gas.

Theoretical prediction the removal of mercury from flue gas by MOFs

KAUST Repository

Liu, Yang

2016-07-19

Removal of mercury from flue gas has been considered as one of the hot topics in both the scientific and industrial world. Adsorption of elemental mercury (Hg) and oxidized mercury species (HgCl, HgO, and HgS) on a novel metal organic framework (MOF) material, named Mg/DOBDC, with unsaturated metal centers was investigated using density functional theory (DFT) calculations. The results show that Hg stably physi-sorbed on the unsaturated metal center (magnesium ion) of Mg/DOBDC with a binding energy (BE) of −27.5 kJ/mol. A direct interaction between Hg and magnesium ion was revealed by the partial density of state (PDOS) analysis. HgCl multi-interacts with two neighboring magnesium ions simultaneously by its Cl endings and thus resulted in strong adsorption strength (−89.0 kJ/mol). The adsorption energies of HgO and HgS on the Mg/DOBDC were as high as −117.0 kJ/mol and −169.7 kJ/mol, respectively, indicating a strong chemisorption. Theoretical calculations in this study reveal that Mg/DOBDC has the potential to serve as an efficient material for removal of mercury from flue gas.

Interaction of nucleic acids with electrically charged surfaces. VII. The effect of ionic strength of neutral medium on the conformation of dna adsorbed on the mercury electrode.

Science.gov (United States)

Brabec, V

1980-02-01

Triangular-wave direct current (d.c.) voltammetry at a hanging mercury drop electrode and phase-selective alternating current (a.c.) polarography at a dropping mercury electrode were used for the investigation of adsorption of double-helical (ds) DNA at mercury electrode surfaces from neutral solutions of 0.05-0.4 M HCOONH4. It was found for the potential region T (from -0.1 V up to ca. -1.0 V) that the height of voltammetric peaks of ds DNA is markedly influenced by the initial potential only at relatively low ionic strength (mu) (from 0.05 up to ca. 0.3). Also a decrease of differential capacity (measured by means of a.c. polarography) in the region T depended markedly on the electrode potential only at relatively low ionic strength. The following conclusions were made concerning the interaction of ds DNA with a mercury electrode charged to potentials of the region T in neutral medium of relatively low ionic strength mu potentials in the Vicinity of the zero charge potential a higher number of ds DNA segments can be opened, probably as a consequence of the strain which could act on the ds DNA molecule in the course of the segmental adsorption/desorption process.

Determination of sub-parts per billion levels of copper in complex matrices by adsorptive string voltammetry on a mercury electrode

International Nuclear Information System (INIS)

Shahbaazi, H.R.; Shahbaazi, H.R.; Safavi, A.; Maleki, N.

2008-01-01

The voltammetric characteristics of Cu(II)-SSA complex at the mercury electrode were investigated. An analytical method that based on the adsorptive accumulation of Cu(II)-SSA complex followed by the reduction of the complexed copper was developed for the copper determination in complex matrices in presence of the large amount of foreign ions. Adsorptive voltammetry determination showed that the Cu(II)-SSA complex behaves irreversibly exchanging two electrons on the hanging mercury drop electrode (HMDE). Factor affecting on the complextion, accumulation and stripping steps were studied and a procedure was developed. The instrumental parameters in the measurement step were also tested. The optimum conditions of pH, SSA concentration, accumulation potential and accumulation time were studied. Under optimal conditions (pH=12.9 glycin Buffer, 7 x 10 - '3 M SSA and accumulation potential -100 mV vs. Ag/ AgCl), a linear calibration graph in the range 1.25 μg L -1 to 42.5 μg L'- 1 and a detection limit of 0.8 μ L -1 were obtained. The average relative standard deviation (RSD) for seven determinations was calculated as 7 %, 5.5 % and 3 % for the concentrations between 3, 15 and 23 μg L'- 1 . The effect of foreign ions and surfactants on the peak height of Cu(II)-SSA complex was evaluated. The method was applied for the determination of the copper in different real samples such as crude oil, crude oil tank button sludge, waste water and tap water samples. The accuracy of the results was checked by ICP. (author)

Highly effective removal of mercury and lead ions from wastewater by mercaptoamine-functionalised silica-coated magnetic nano-adsorbents: Behaviours and mechanisms

Energy Technology Data Exchange (ETDEWEB)

Bao, Shuangyou; Li, Kai; Ning, Ping [Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, YunNan, KunMing, 650500 (China); Peng, Jinhui [Faculty of Metallurgical and Energy, Kunming University of Science and Technology, YunNan, KunMing 650500 (China); Jin, Xu [Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, YunNan, KunMing, 650500 (China); Tang, Lihong, E-mail: luckyman@163.com [Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, YunNan, KunMing, 650500 (China)

2017-01-30

Highlights: • Highly effective removal of Hg(II) and Pb(II) ions from wastewater. • This adsorbent had multiple adsorption sites (sulfur and amine sites) on the surface. • This adsorbent had better tolerance to low pH for removal of Hg(II). • This new hybrid material was much cheaper and no secondary pollution. • This adsorbent shows notable advantages including easy separation and recyclability. - Abstract: A novel hybrid material was fabricated using mercaptoamine-functionalised silica-coated magnetic nanoparticles (MAF-SCMNPs) and was effective in the extraction and recovery of mercury and lead ions from wastewater. The properties of this new magnetic material were explored using various characterisation and analysis methods. Adsorbent amounts, pH levels and initial concentrations were optimised to improve removal efficiency. Additionally, kinetics, thermodynamics and adsorption isotherms were investigated to determine the mechanism by which the fabricated MAF-SCMNPs adsorb heavy metal ions. The results revealed that MAF-SCMNPs were acid-resistant. Sorption likely occurred by chelation through the amine group and ion exchange between heavy metal ions and thiol functional groups on the nanoadsorbent surface. The equilibrium was attained within 120 min, and the adsorption kinetics showed pseudo-second-order (R{sup 2} > 0.99). The mercury and lead adsorption isotherms were in agreement with the Freundlich model, displaying maximum adsorption capacities of 355 and 292 mg/g, respectively. The maximum adsorptions took place at pH 5–6 and 6–7 for Hg(II) and Pb(II), respectively. The maximum adsorptions were observed at 10 mg and 12 mg adsorbent quantities for Hg(II) and Pb(II), respectively. The adsorption process was endothermic and spontaneous within the temperature range of 298–318 K. This work demonstrates a unique magnetic nano-adsorbent for the removal of Hg(II) and Pb(II) from wastewater.

Mercury in mercury(II)-spiked soils is highly susceptible to plant bioaccumulation.

Science.gov (United States)

Hlodák, Michal; Urík, Martin; Matúš, Peter; Kořenková, Lucia

2016-01-01

Heavy metal phytotoxicity assessments usually use soluble metal compounds in spiked soils to evaluate metal bioaccumulation, growth inhibition and adverse effects on physiological parameters. However, exampling mercury phytotoxicity for barley (Hordeum vulgare) this paper highlights unsuitability of this experimental approach. Mercury(II) in spiked soils is extremely bioavailable, and there experimentally determined bioaccumulation is significantly higher compared to reported mercury bioaccumulation efficiency from soils collected from mercury-polluted areas. Our results indicate this is not affected by soil sorption capacity, thus soil ageing and formation of more stable mercuric complexes with soil fractions is necessary for reasonable metal phytotoxicity assessments.

Distribution of mercury in a tropical estuary (India) situated near a chloro-alkali plant

OpenAIRE

Gouda, Rajashree; Panigrahy, R.C.

1995-01-01

The distribution of mercury in water, sediment and some biological samples of the Rushikulya estuary, east coast of India were assessed during Jan-Dec. 1989. Both the dissolved plus acid leachable mercury contents in water and the sediment mercury discerned conspicuous spatial and seasonal fluctuations. Adsorption on to the suspended particulates was found to be the most likely mechanism for removal of mercury from the water column. Exchange of mercury from sediments to water was observed at ...

Mercury separation from concentrated potassium iodide/iodine leachate using Self-Assembled Mesoporous Mercaptan Support (SAMMS) technology

International Nuclear Information System (INIS)

Mattigod, S.V.; Feng, X.; Fryxell, G.E.

1997-10-01

A study was conducted to demonstrate the effectiveness of a novel adsorber, the Self-Assembled Mesoporous Mercaptan Support (SAMMS) material to remove mercury (Hg) from potassium iodide/iodine (KI/I 2 ) waste streams. This study included investigations of the SAMMS material''s binding kinetics, loading capacity, and selectivity for Hg adsorption from surrogate and actual KI/I 2 waste solutions. The kinetics data showed that binding of Hg by the adsorber material occurs very rapidly, with 82% to 95% adsorption occurring within the first 5 min. No significant differences in the rate of adsorption were noted between pH values of 5 and 9 and at Hg concentrations of ∼100 mg/1. Within the same range of pH values, an approximate four-fold increase in initial Hg concentration resulted in a two-fold increase in the rate of adsorption. In all cases studied, equilibrium adsorption occured within 4 h. The loading capacity experiments in KI/I 2 surrogate solutions indicated Hg adsorption densities between 26 to 270 mg/g. The loading density increased with increasing solid: solution ratio and decreasing iodide concentrations. Values of distribution coefficients (1.3x10 5 to >2.6x10 8 ml/g) indicated that material adsorbs Hg with very high specificity from KI/I 2 surrogate solutions. Reduction studies showed that compared to metallic iron (Fe), sodium dithionite can very rapidly reduce iodine as the triiodide species into the iodide form. Adsorption studies conducted with actual KI/I 2 leachates confirmed the highly specific Hg adsorption properties (K d >6x10 7 to>1x10 8 ml//g) of the adsorber material. Following treatment, the Hg concentrations in actual leachates were below instrumental detection limits (i.e., < 0.00005 mg/l), indicating that the KI solutions can be recycled

Synthesis of alumina nano-sheets via supercritical fluid technology with high uranyl adsorptive capacity

International Nuclear Information System (INIS)

Jing Yu; Jun Wang; Zhanshuang Li; Qi Liu; Milin Zhang; Hongbin Bai; Caishan Jiao; Jun Wang; Lianhe Liu

2012-01-01

Supercritical carbon dioxide is beneficial to the synthesis of superior ultrafine and uniform materials due to its high chemical stability, low viscosity, high diffusivity, and 'zero' surface tension. γ-Alumina nano-sheets were obtained by a simple hydrothermal route in the presence of supercritical carbon dioxide. XRD, FTIR, SEM, TEM and nitrogen sorption isotherm were employed to characterize the samples. Alumina as-prepared has a high specific surface area of up to 200 ± 6 m 2 g -1 , which presents a high adsorption capacity (4.66 ± 0.02 mg g -1 ) for uranyl ions from aqueous solution. Furthermore, the adsorption process was found to be endothermic and spontaneous in nature. (authors)

Strong adsorbability of mercury ions on aniline/sulfoanisidine copolymer nanosorbents.

Science.gov (United States)

Li, Xin-Gui; Feng, Hao; Huang, Mei-Rong

2009-01-01

The highest Hg-ion adsorbance so far, namely up to 2063 mg g(-1), has been achieved by poly(aniline-co-5-sulfo-2-anisidine) nanosorbents. Sorption of Hg ions occurs mainly by redox and chelation mechanisms (see scheme), but also by ion exchange and physisorption.Poly(aniline (AN)-co-5-sulfo-2-anisidine (SA)) nanoparticles were synthesized by chemical oxidative copolymerization of AN and SA monomers, and their extremely strong adsorption of mercury ions in aqueous solution was demonstrated. The reactivity ratios of AN and SA comonomers were found to be 2.05 and 0.02, respectively. While AN monomer tends to homopolymerize, SA monomer tends to copolymerize with AN monomer because of the great steric hindrance and electron-attracting effect of the sulfo groups, despite the effect of conjugation of the methoxyl group with the benzene ring. The effects of initial mercury(II) concentration, sorption time, sorption temperature, ultrasonic treatment, and sorbent dosage on mercury-ion sorption onto AN/SA (50/50) copolymer nanoparticles with a number-average diameter of around 120 nm were significantly optimized. The results show that the maximum Hg-ion sorption capacity on the particulate nanosorbents can even reach 2063 mg of Hg per gram of sorbent, which would be the highest Hg-ion adsorbance so far. The sorption data fit to the Langmuir isotherm, and the process obeys pseudo-second-order kinetics. The IR and UV/Vis spectral data of the Hg-loaded copolymer particles suggest that some mercury(II) was directly reduced by the copolymer to mercury(I) and even mercury(0). A mechanism of sorption between the particles and Hg ions in aqueous solution is proposed, and a physical/ion exchange/chelation/redox sorption ratio of around 2/3/45/50 was found. Copolymer nanoparticles may be one of the most powerful and cost-effective sorbents of mercury ions, with a wide range of potential applications for the efficient removal and even recovery of the mercury ions from aqueous solution.

Phragmites karka as a Biosorbent for the Removal of Mercury Metal Ions from Aqueous Solution: Effect of Modification

Directory of Open Access Journals (Sweden)

Muhammad Hamid Raza

2015-01-01

Full Text Available Batch scale studies for the adsorption potential of novel biosorbent Phragmites karka (Trin, in its natural and treated forms, were performed for removal of mercury ions from aqueous solution. The study was carried out at different parameters to obtain optimum conditions of pH, biosorbent dose, agitation speed, time of contact, temperature, and initial metal ion concentration. To analyze the suitability of the process and maximum amount of metal uptake, Dubinin-Radushkevich (D-R model, Freundlich isotherm, and Langmuir isotherm were applied. The values of qmax for natural and treated biosorbents were found at 1.79 and 2.27 mg/g, respectively. The optimum values of contact time and agitation speed were found at 50 min and 150 rpm for natural biosorbent whereas 40 min and 100 rpm for treated biosorbent, respectively. The optimum biosorption capacities were observed at pH 4 and temperature 313 K for both natural P. karka and treated P. karka. RL values indicate that comparatively treated P. karka was more feasible for mercury adsorption compared to natural P. karka. Both pseudo-first-order and pseudo-second-order kinetic models were applied and it was found that data fit best to the pseudo-second-order kinetic model. Thermodynamic studies indicate that adsorption process was spontaneous, feasible, and endothermic.

Mercury transformation and speciation in flue gases from anthropogenic emission sources: a critical review

Science.gov (United States)

Zhang, Lei; Wang, Shuxiao; Wu, Qingru; Wang, Fengyang; Lin, Che-Jen; Zhang, Leiming; Hui, Mulin; Yang, Mei; Su, Haitao; Hao, Jiming

2016-02-01

Mercury transformation mechanisms and speciation profiles are reviewed for mercury formed in and released from flue gases of coal-fired boilers, non-ferrous metal smelters, cement plants, iron and steel plants, waste incinerators, biomass burning and so on. Mercury in coal, ores, and other raw materials is released to flue gases in the form of Hg0 during combustion or smelting in boilers, kilns or furnaces. Decreasing temperature from over 800 °C to below 300 °C in flue gases leaving boilers, kilns or furnaces promotes homogeneous and heterogeneous oxidation of Hg0 to gaseous divalent mercury (Hg2+), with a portion of Hg2+ adsorbed onto fly ash to form particulate-bound mercury (Hgp). Halogen is the primary oxidizer for Hg0 in flue gases, and active components (e.g., TiO2, Fe2O3, etc.) on fly ash promote heterogeneous oxidation and adsorption processes. In addition to mercury removal, mercury transformation also occurs when passing through air pollution control devices (APCDs), affecting the mercury speciation in flue gases. In coal-fired power plants, selective catalytic reduction (SCR) system promotes mercury oxidation by 34-85 %, electrostatic precipitator (ESP) and fabric filter (FF) remove over 99 % of Hgp, and wet flue gas desulfurization system (WFGD) captures 60-95 % of Hg2+. In non-ferrous metal smelters, most Hg0 is converted to Hg2+ and removed in acid plants (APs). For cement clinker production, mercury cycling and operational conditions promote heterogeneous mercury oxidation and adsorption. The mercury speciation profiles in flue gases emitted to the atmosphere are determined by transformation mechanisms and mercury removal efficiencies by various APCDs. For all the sectors reviewed in this study, Hgp accounts for less than 5 % in flue gases. In China, mercury emission has a higher Hg0 fraction (66-82 % of total mercury) in flue gases from coal combustion, in contrast to a greater Hg2+ fraction (29-90 %) from non-ferrous metal smelting, cement and

Superb adsorption capacity of hierarchical calcined Ni/Mg/Al layered double hydroxides for Congo red and Cr(VI) ions

Energy Technology Data Exchange (ETDEWEB)

Lei, Chunsheng [State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China); College of Environmental & Safety Engineering, Changzhou University, Changzhou 213164 (China); Zhu, Xiaofeng [College of Environmental & Safety Engineering, Changzhou University, Changzhou 213164 (China); Zhu, Bicheng; Jiang, Chuanjia; Le, Yao [State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China); Yu, Jiaguo, E-mail: jiaguoyu@yahoo.com [State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China); Department of Physics, Faculty of Science, King Abdulaziz University, Jeddah 21589 (Saudi Arabia)

2017-01-05

Highlights: • Ni/Mg/Al layered double hydroxides (NMA-LDHs) synthesized. • NMA-LDHs with hierarchically hollow microsphere structure. • Calcined NMA-LDHs have large adsorption capacities for CR and Cr(VI) ions. - Abstract: The preparation of hierarchical porous materials as catalysts and sorbents has attracted much attention in the field of environmental pollution control. Herein, Ni/Mg/Al layered double hydroxides (NMA-LDHs) hierarchical flower-like hollow microspheres were synthesized by a hydrothermal method. After the NMA-LDHs was calcined at 600 °C, NMA-LDHs transformed into Ni/Mg/Al layered double oxides (NMA-LDOs), which maintained the hierarchical flower-like hollow structure. The crystal phase, morphology, and microstructure of the as-prepared samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy elemental mapping, Fourier transform infrared spectroscopy, and nitrogen adsorption−desorption methods. Both the calcined and non-calcined NMA-LDHs were examined for their performance to remove Congo red (CR) and hexavalent chromium (Cr(VI)) ions in aqueous solution. The maximum monolayer adsorption capacities of CR and Cr(VI) ions over the NMA-LDOs sample were 1250 and 103.4 mg/g at 30 °C, respectively. Thermodynamic studies indicated that the adsorption process was endothermic in nature. In addition, the addition of coexisting anions negatively influenced the adsorption capacity of Cr(VI) ions, in the following order: CO{sub 3}{sup 2−} > SO{sub 4}{sup 2−} > H{sub 2}PO{sub 4}{sup −} > Cl{sup −}. This work will provide new insight into the design and fabrication of advanced adsorption materials for water pollutant removal.

Novel hollow microspheres of hierarchical zinc-aluminum layered double hydroxides and their enhanced adsorption capacity for phosphate in water

International Nuclear Information System (INIS)

Zhou, Jiabin; Yang, Siliang; Yu, Jiaguo; Shu, Zhan

2011-01-01

Highlights: → Hierarchical Zn-Al LDHs hollow microspheres were first synthesized by a simple hydrothermal method using urea as precipitating agent. → The morphology of Zn-Al LDHs can be tailored from irregular platelet to hollow microspheres by simply varying concentrations of urea. → The as-prepared samples exhibit high adsorption capacity (54.1-232 mg/g) for phosphate from aqueous solution. - Abstract: Hollow microspheres of hierarchical Zn-Al layered double hydroxides (LDHs) were synthesized by a simple hydrothermal method using urea as precipitating agent. The morphology and microstructure of the as-prepared samples were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), nitrogen adsorption-desorption isotherms and fourier transform infrared (FTIR) spectroscopy. It was found that the morphology of hierarchical Zn-Al LDHs can be tuned from irregular platelets to hollow microspheres by simply varying concentrations of urea. The effects of initial phosphate concentration and contact time on phosphate adsorption using various Zn-Al LDHs and their calcined products (LDOs) were investigated from batch tests. Our results indicate that the equilibrium adsorption data were best fitted by Langmuir isothermal model, with the maximum adsorption capacity of 54.1-232 mg/g; adsorption kinetics follows the pseudo-second-order kinetic equation and intra-particle diffusion model. In addition, Zn-Al LDOs are shown to be effective adsorbents for removing phosphate from aqueous solutions due to their hierarchical porous structures and high specific surface areas.

Mercury embrittlement of Cu-Al alloys under cyclic loading

Science.gov (United States)

Regan, T. M.; Stoloff, N. S.

1977-01-01

The effect of mercury on the room temperature, high cycle fatigue properties of three alloys: Cu-5.5 pct Al, Cu-7.3 pct Al, and Cu-6.3 pct Al-2.5 pct Fe has been determined. Severe embrittlement under cyclic loading in mercury is associated with rapid crack propagation in the presence of the liquid metal. A pronounced grain size effect is noted under mercury, while fatigue properties in air are insensitive to grain size. The fatigue results are discussed in relation to theories of adsorption-induced liquid metal embrittlement.

[Blood plasma protein adsorption capacity of perfluorocarbon emulsion stabilized by proxanol 268 (in vitro and in vivo studies)].

Science.gov (United States)

Sklifas, A N; Zhalimov, V K; Temnov, A A; Kukushkin, N I

2012-01-01

The adsorption abilities of the perfluorocarbon emulsion stabilized by Proxanol 268 were investigated in vitro and in vivo. In vitro, the saturation point for the blood plasma proteins was nearly reached after five minutes of incubation of the emulsion with human/rabbit blood plasma and was stable for all incubation periods studied. The decrease in volume ratio (emulsion/plasma) was accompanied by the increase in the adsorptive capacity of the emulsion with maximal values at 1/10 (3.2 and 1.5 mg of proteins per 1 ml of the emulsion, for human and rabbit blood plasma, respectively) that was unchanged at lower ratios. In vivo, in rabbits, intravenously injected with the emulsion, the proteins with molecular masses of 12, 25, 32, 44, 55, 70, and 200 kDa were adsorbed by the emulsion (as in vitro) if it was used 6 hours or less before testing. More delayed testing (6 h) revealed elimination of proteins with molecular masses of 25 and 44 kDa and an additional pool of adsorpted new ones of 27, 50, and 150 kDa. Specific adsorptive capacity of the emulsion enhanced gradually after emulsion injection and reached its maximum (3.5-5 mg of proteins per 1 ml of the emulsion) after 24 hours.

Mathematical modeling of the integrated process of mercury bioremediation in the industrial bioreactor

OpenAIRE

Głuszcz, Paweł; Petera, Jerzy; Ledakowicz, Stanisław

2010-01-01

The mathematical model of the integrated process of mercury contaminated wastewater bioremediation in a fixed-bed industrial bioreactor is presented. An activated carbon packing in the bioreactor plays the role of an adsorbent for ionic mercury and at the same time of a carrier material for immobilization of mercury-reducing bacteria. The model includes three basic stages of the bioremediation process: mass transfer in the liquid phase, adsorption of mercury onto activated carbon and ionic me...

Heavy metal ion adsorption onto polypyrrole-impregnated porous carbon.

Science.gov (United States)

Choi, Moonjung; Jang, Jyongsik

2008-09-01

Polypyrrole-impregnated porous carbon was readily synthesized using vapor infiltration polymerization of pyrrole monomers. The results show that the functionalized polymer layer was successfully coated onto the pore surface of carbon without collapse of mesoporous structure. The modified porous carbon exhibited an improved complexation affinity for heavy metal ions such as mercury, lead, and silver ions due to the amine group of polypyrrole. The introduced polypyrrole layer could provide the surface modification to be applied for heavy metal ion adsorbents. Especially, polymer-impregnated porous carbon has an enhanced heavy metal ion uptake, which is 20 times higher than that of adsorbents with amine functional groups. Furthermore, the relationship between the coated polymer amount and surface area was also investigated in regard to adsorption capacity.

Adsorptive behaviour of mercury on algal biomass: Competition with divalent cations and organic compounds

International Nuclear Information System (INIS)

Carro, Leticia; Barriada, Jose L.; Herrero, Roberto; Sastre de Vicente, Manuel E.

2011-01-01

Highlights: → Native and protonated macroalga S. muticum are good materials for mercury removal. → Fast kinetic process and high mercury uptakes have been found for those materials. → Diffusion control is the rate limiting step of the process. → Competition effects by organic compounds, inorganic salts and divalent cations were analyzed. → Continuous flow experiments allowed identification of mercury reduction during metal removal. - Abstract: Biosorption processes constitute an effective technique for mercury elimination. Sorption properties of native and acid-treated Sargassum muticum have been studied. Effect of pH, initial mercury concentration and contact time studies provided fundamental information about the sorption process. This information was used as the reference values to analyse mercury sorption under competition conditions. Saline effect has shown little influence in sorption, when only electrostatic modifications took place upon salt addition. On the contrary, if mercury speciation dramatically changed owing to the addition of an electrolyte, such as in the case of chloride salt, very large modifications in mercury sorption were observed. Competition with other divalent cations or organic compounds has shown little or none effect on mercury, indicating that a different mechanism is taking place during the removal of these pollutants. Finally, continuous flow experiments have clearly shown that a reduction process is also taking place during mercury removal. This fact is not obvious to elucidate under batch sorption experiments. Scanning Electron Microscopy analysis of the surface of the materials show deposits of mercury(I) and metallic mercury which is indicative of the reduction process proposed.

An insight into the removal of Cu (II) and Pb (II) by aminopropyl-modified mesoporous carbon CMK-3: Adsorption capacity and mechanism

Energy Technology Data Exchange (ETDEWEB)

Hamad, Hussein, E-mail: hussein.hamad@ul.edu.lb [Platform for Research and Analysis in Environmental Sciences (PRASE), Lebanese University, Beirut (Lebanon); Ezzeddine, Zeinab; Lakis, Fatima; Rammal, Hassan [Platform for Research and Analysis in Environmental Sciences (PRASE), Lebanese University, Beirut (Lebanon); Srour, Mortada [Lebanese University, Faculty of Sciences (I), Hadath, Beirut (Lebanon); Hijazi, Akram [Platform for Research and Analysis in Environmental Sciences (PRASE), Lebanese University, Beirut (Lebanon)

2016-08-01

In this study, the adsorption of heavy metal ions onto ordered mesoporous carbon CMK-3 was investigated. CMK-3 has been synthesized using SBA-15 as the hard template and then directly amino-functionalized by the treatment with 3-aminopropyltrimethoxysilane (APTMS) without the need of oxidation before. The thus obtained modified mesoporous carbon has been characterized by nitrogen sorption, X-ray diffraction and infrared spectroscopy. Its adsorption efficiency for the removal of Cu{sup 2+} and Pb{sup 2+} from aqueous solutions was tested. The effects of contact time, pH and initial metal ions concentration were investigated as well. The adsorption capacities were very high (3.5 mmol g{sup −1} and 8.6 mmol g{sup −1} for Pb{sup 2+} and Cu{sup 2+} respectively). These values depend largely on the speciation of metal ions as a function of pH. The selectivity was also dependent on the nature of metal ions rather than the adsorbent used. The mechanism of adsorption is complex where several types of interaction between metal ions and the adsorbent surface are involved. - Highlights: • Mesoporous carbon CMK-3 was successfully synthesized and functionalized. • No oxidation treatment was done prior to aminopropyl functionalization. • The adsorbent adsorption capacity is high (3.5 mmol g{sup −1} for Cu{sup 2+} and 8.6 mmol g{sup −1} for Pb{sup 2+}). • The maximum Cu{sup 2+} adsorption capacity is related to its speciation as a function of pH. • The mechanism of adsorption is complex including different types of interaction.

A one-step thermal decomposition method to prepare anatase TiO2 nanosheets with improved adsorption capacities and enhanced photocatalytic activities

International Nuclear Information System (INIS)

Li, Wenting; Shang, Chunli; Li, Xue

2015-01-01

Highlights: • Anatase TiO 2 nanosheets (NSs) with high surface area have been prepared. • Only one type of surfactant, oleylamine (OM), is used as capping agents. • TiO 2 NSs possess high adsorption capacities MB and high photocatalytic activity. - Abstract: Anatase TiO 2 nanosheets (NSs) with high surface area have been prepared via a one-step thermal decomposition of titanium tetraisopropoxide (TTIP) in oleylamine (OM), and their adsorption capacities and photocatalytic activities are investigated by using methylene blue (MB) and methyl orange (MO) as model pollutants. During the synthesis procedure, only one type of surfactant, oleylamine (OM), is used as capping agents and no other solvents are added. Structure and properties of the TiO 2 NSs were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), N 2 adsorption analysis, UV–vis spectrum, X-ray photoelectron spectroscopy (XPS) and Photoluminescence (PL) methods. The results indicate that the TiO 2 NSs possess high surface area up to 378 m 2 g −1 . The concentration of capping agents is found to be a key factor controlling the morphology and crystalline structure of the product. Adsorption and photodegradation experiments reveal that the prepared TiO 2 NSs possess high adsorption capacities of model pollutants MB and high photocatalytic activity, showing that TiO 2 NSs can be used as efficient pollutant adsorbents and photocatalytic degradation catalysts of MB in wastewater treatment.

Removal and recovery of gas-phase element mercury by metal oxide-loaded activated carbon

International Nuclear Information System (INIS)

Mei Zhijian; Shen Zhemin; Zhao Qingjie; Wang Wenhua; Zhang Yejian

2008-01-01

The reusability of Co 3 O 4 (AC-Co), MnO 2 (AC-Mn) and CuCoO 4 (AC-CC) loaded activated carbon (AC) and their element mercury removal efficiency had been studied using a laboratory-scale fixed-bed reactor under simulated flue gas conditions. Tests showed that spent AC-Co could be regenerated through heating at 673 K under N 2 atmosphere and the enrichment regenerated Hg 0 could be collected to eliminate the secondary pollution. Regenerated AC-Mn and AC-CC's Hg 0 removal efficiency decreased greatly due to AC's decomposition and MnO 2 's crystal structure variation. Compared with AC and metal oxides, metal oxide-loaded AC had higher Hg 0 capture ability and capacity due to AC huge surface areas and lots of function groups. TGA analysis results showed that AC-Co and AC-Mn's HgO adsorptive capacity at 523 K reached 19.8 mg g -1 and 5.21 mg g -1 , respectively. High loading values and adsorption temperatures were beneficial to AC-Co's Hg 0 removal efficiency. However, CuCoO 4 and MnO 2 's AC decomposition ability had negative effect on AC-CC and AC-Mn's performance, respectively, especially at high adsorption temperatures and loading values. SO 2 tests showed that AC-CC had higher anti SO 2 -poisoning ability than AC-Co and AC-Mn

First principles study of elemental mercury (Hg{sup 0}) adsorption on low index CoMnO{sub 3} surfaces

Energy Technology Data Exchange (ETDEWEB)

Ji, Wenchao; Su, Pingru; Tang, Qingli; Cheng, Zhiwen [School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai, 200240 (China); Shen, Zhemin, E-mail: zmshen@sjtu.edu.cn [School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai, 200240 (China); Fan, Maohong [Department of Chemical and Petroleum Engineering, University of Wyoming, Laramie, Wyoming, 82071 (United States); School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, Georgia, 30332 (United States)

2017-06-30

Highlights: • Hg{sup 0} adsorption on low index CoMnO{sub 3} surface was predicted by DFT method. • Hg{sup 0} is adsorbed on the CoMnO{sub 3} surface with chemisorption interaction. • Hg{sup 0} has highest adsorption energy on CoMnO{sub 3} (1 0 0) surface with Hg-Mn mechanism. • The electron transfer of Hg{sup 0} has positive relationship with adsorption energy. - Abstract: The density functional theory (DFT) is applied to predict elemental mercury (Hg{sup 0}) adsorption on CoMnO{sub 3} surface for the first time. GGA/PBE functional were selected to determine the potential Hg{sup 0} capture mechanisms. The results show that Hg{sup 0} has good affinity with CoMnO{sub 3} surfaces with chemical adsorption. The adsorption energy of Hg{sup 0}-CoMnO{sub 3} (1 0 0), Hg{sup 0}-CoMnO{sub 3} (1 0 1) and Hg{sup 0}-CoMnO{sub 3} (1 1 0) are −85.225, −72.305 and −70.729 kJ/mol, respectively. The Hg-Mn and Hg-Co mechanisms were revealed on low index surfaces. Hg{sup 0} was oxidized to its valence state of 0.236 on Mn site in CoMnO{sub 3} (1 0 0) surface. The Hg-Co interaction mechanism occurred on Hg{sup 0}-CoMnO{sub 3} (1 0 1) and Hg{sup 0}-CoMnO{sub 3} (1 1 0) with 0.209e{sup −} and 0.189e{sup −} transformation, respectively. The PDOS analysis shows that Hg-Mn interaction depends on the hybridization of Hg(s- and d-orbitals) and Mn (s-, p- and d- orbitals). However, Hg-Co interaction stems from s- and d- orbitals of Hg, which only overlapping with d- and p- orbital of Co. Both the adsorption energy and electronic structure analysis indicated that CoMnO{sub 3} catalyst performed excellent in Hg{sup 0} oxidation. Exposing CoMnO{sub 3} (1 0 0) is most favorable in Hg{sup 0} control, which provides theoretical instruction on certain crystal plane synthesis in experiment.

Density functional investigation of mercury and arsenic adsorption on nitrogen doped graphene decorated with palladium clusters: A promising heavy metal sensing material in farmland

International Nuclear Information System (INIS)

Zhao, Chunjiang; Wu, Huarui

2017-01-01

Highlights: • PNG can be acted as micro-sensor for monitoring heavy metal in agriculture. • The most favorable adsorption site of Pd atom or cluster on PNG is the vacancy site. • The Pd atom or cluster enhance the reactivity of PNG toward Hg and AsH_3 adsorption. • The efficiency of a sorbent can be tuned by tailoring the ε_d of adsorbed metals. - Abstract: Density functional theory calculations are carried out to study the adsorption of mercury and arsenic on Pd_n (n = 1–6) supported on pyridine-like nitrogen doped graphene (PNG). Owing to the promising sensitivity in trace amounts of atoms or molecules, PNG can be acted as micro-sensor for sensing heavy metals in agriculture soils. Through the analyses of structural and electronic properties of pristine PNG and Pd atom decorated PNG, we find that the most favorable adsorption site for Pd atom is the vacancy site. The analyses of structural and electronic properties reveal that the Pd atom or clusters can enhance the reactivity for Hg and AsH_3 adsorption on PNG. The adsorption ability of Hg on Pd_n decorated PNG is found to be related to the d-band center (ε_d) of the Pd_n, in which the closer ε_d of Pd_n to the Fermi level, the higher adsorption strength for Hg on Pd_n decorated PNG. Moreover, the charge transfer between Pd_n and arsenic may constitute arsenic adsorption on Pd_n decorated PNG. Further design of highly efficient carbon based sorbents for heavy metals removal should be focused on tailoring ε_d of adsorbed metals.

Evaluation of Adsorption Capacity of Chitosan-Citral Schiff Base for Wastewater Pre-Treatment in Dairy Industries

Directory of Open Access Journals (Sweden)

Desislava K. Tsaneva

2017-06-01

Full Text Available In this study, we aimed to evaluate the adsorption capacity of the Schiff base chitosan-citral for its application in dairy wastewater pre-treatment. Chemical oxygen demand (COD reduction was the factor used to evaluate the adsorption efficiency. The maximum COD percentage reduction of 35.3% was obtained at 40.0 °C, pH 9.0, adsorbent dose 15 g L-1, contact time 180 min and agitation speed 100 rpm. It was found that the Langmuir isotherm fitted well the equilibrium data of COD uptake (R2 = 0.968, whereas the kinetic data were best fitted by the pseudo-second order model (R2=0.999. Enhancement of the adsorption efficiency up to 29.8% in dependence of the initial COD concentration of the dairy wastewater was observed by adsorption with the Schiff base chitosan-citral adsorbent compared to the non-modified chitosan at the same experimental conditions. The results indicated that the Schiff base chitosan-citral can be used for dairy wastewater physicochemical pretreatment by adsorption, which might be applied before the biological unit in the wastewater treatment plant to reduce the load.

Environmentally benign working pairs for adsorption refrigeration

International Nuclear Information System (INIS)

Cui Qun; Tao Gang; Chen Haijun; Guo Xinyue; Yao Huqing

2005-01-01

This paper begins from adsorption working pairs: water and ethanol were selected as refrigerants; 13x molecular sieve, silica gel, activated carbon, adsorbent NA and NB, proposed by authors, were selected as adsorbents, and the performance of adsorption working pairs in adsorption refrigeration cycle was studied. The adsorption isotherms of adsorbents (NA and NB) were obtained by high-vacuum gravimetric method. Desorption properties of adsorbents were analyzed and compared by thermal analysis method. The performance of adsorption refrigeration was studied on simulation device of adsorption refrigeration cycle. After presentation of adsorption isotherms, the thermodynamic performance for their use in adsorption refrigeration system was calculated. The results show: (1) the maximum adsorption capacity of water on adsorbent NA reaches 0.7 kg/kg, and the maximum adsorption capacity of ethanol on adsorbent NB is 0.68 kg/kg, which is three times that of ethanol on activated carbon, (2) the refrigeration capacity of NA-water working pair is 922 kJ/kg, the refrigeration capacity of NB-ethanol is 2.4 times that of activated carbon-methanol, (3) as environmental friendly and no public hazard adsorption working pair, NA-H 2 O and NB-ethanol can substitute activated carbon-methanol in adsorption refrigeration system using low-grade heat source

Cadmium Adsorption on HDTMA Modified Montmorillionite

Directory of Open Access Journals (Sweden)

Mohd. Elmuntasir I. Ahmed

2009-06-01

Full Text Available In this paper the possibility of cadmium removal from aqueous solutions by adsorption onto modified montmorillonite clay is investigated. Batch adsorption experiments performed revealed an enhanced removal of cadmium using HDTMA modified montmorillonite to 100% of its exchange capacity. Modified montmorillonite adsorption capacity increases at higher pHs suggesting adsorption occurs as a result of surface precipitation and HDTMA complex formation due to the fact that the original negatively charged montmorillonite is now covered by a cationic layer of HDTMA. Adsorption isotherms generated followed a Langmuir isotherm equation possibly indicating a monolayer coverage. Adsorption capacities of up to 49 mg/g and removals greater than 90% were achieved. Anionic selectivity of the HDTMA modified monmorillonite is particularly advantageous in water treatment applications where high concentrations of less adsorbable species are present, and the lack of organoclay affinity for these species may allow the available capacity to be utilized selectively by the targeted species.

Equilibrium and kinetics study on hexavalent chromium adsorption onto diethylene triamine grafted glycidyl methacrylate based copolymers

International Nuclear Information System (INIS)

Maksin, Danijela D.; Nastasović, Aleksandra B.; Milutinović-Nikolić, Aleksandra D.; Suručić, Ljiljana T.; Sandić, Zvjezdana P.; Hercigonja, Radmila V.; Onjia, Antonije E.

2012-01-01

Highlights: ► Methacrylate based copolymers grafted with diethylene triamine as Cr(VI) sorbents. ► Chemisorption and pore diffusion are characteristics of this sorption system. ► Langmuir isotherm provided best fit and maximum adsorption capacity was 143 mg g −1 . ► Cr(VI) sorption onto amino-functionalized copolymer was endothermic and spontaneous. ► A simple, efficient and cost-effective hexavalent chromium removal method. - Abstract: Two porous and one non-porous crosslinked poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate) [abbreviated PGME] were prepared by suspension copolymerization and functionalized with diethylene triamine [abbreviated PGME-deta]. Samples were characterized by elemental analysis, mercury porosimetry, scanning electron microscopy with energy-dispersive X-ray spectroscopy, and transmission electron microscopy. Kinetics of Cr(VI) sorption by PGME-deta were investigated in batch static experiments, in the temperature range 25–70 °C. Sorption was rapid, with the uptake capacity higher than 80% after 30 min. Sorption behavior and rate-controlling mechanisms were analyzed using five kinetic models (pseudo-first order, pseudo-second order, Elovich, intraparticle diffusion and Bangham model). Kinetic studies showed that Cr(VI) adsorption adhered to the pseudo-second-order model, with definite influence of pore diffusion. Equilibrium data was tested with Langmuir, Freundlich and Tempkin adsorption isotherm models. Langmuir model was the most suitable indicating homogeneous distribution of active sites on PGME-deta and monolayer sorption. The maximum adsorption capacity from the Langmuir model, Q max , at pH 1.8 and 25 °C was 143 mg g −1 for PGME2-deta (sample with the highest amino group concentration) while at 70 °C Q max reached the high value of 198 mg g −1 . Thermodynamic parameters revealed spontaneous and endothermic nature of Cr(VI) adsorption onto PGME-deta.

Removal of mercury from water by carbonaceous sorbents derived from walnut shell

International Nuclear Information System (INIS)

Zabihi, M.; Ahmadpour, A.; Asl, A. Haghighi

2009-01-01

The adsorption ability of a powdered activated carbon (PAC) derived from walnut shell was investigated in an attempt to produce more economic and effective sorbent for the control of Hg(II) ion from industrial liquid streams. Carbonaceous sorbents derived from Iranian walnut shell (WS) were prepared by chemical activation method using ZnCl 2 as an activating reagent. To the best of our knowledge, this adsorbent was not used before for removing mercury from water. Adsorption of Hg(II) from aqueous solutions was carried out under different experimental conditions by varying treatment time, metal ion concentration, adsorbent amount, pH and solution temperature. It was determined that Hg(II) adsorption follows both Langmuir and Freundlich isotherms as well as pseudo-second-order kinetics. It was also shown that Hg(II) uptake decreases with increasing pH of the solution. The proper choice of preparation conditions resulted in a microporous activated carbon with 0.45 g/cm 3 density, 737 mg/g iodine number and 780 m 2 /g BET surface area. The monolayer sorption capacity of this optimum adsorbent was obtained as 151.5 mg/g.

Impacts of acid gases on mercury oxidation across SCR catalyst

International Nuclear Information System (INIS)

Zhuang, Ye; Laumb, Jason; Liggett, Richard; Holmes, Mike; Pavlish, John

2007-01-01

A series of bench-scale experiments were completed to evaluate acid gases of HCl, SO 2 , and SO 3 on mercury oxidation across a commercial selective catalytic reduction (SCR) catalyst. The SCR catalyst was placed in a simulated flue gas stream containing O 2 , CO 2 , H 2 O, NO, NO 2 , and NH 3 , and N 2 . HCl, SO 2 , and SO 3 were added to the gas stream either separately or in combination to investigate their interactions with mercury over the SCR catalyst. The compositions of the simulated flue gas represent a medium-sulfur and low- to medium-chlorine coal that could represent either bituminous or subbituminous. The experimental data indicated that 5-50 ppm HCl in flue gas enhanced mercury oxidation within the SCR catalyst, possibly because of the reactive chlorine species formed through catalytic reactions. An addition of 5 ppm HCl in the simulated flue gas resulted in mercury oxidation of 45% across the SCR compared to only 4% mercury oxidation when 1 ppm HCl is in the flue gas. As HCl concentration increased to 50 ppm, 63% of Hg oxidation was reached. SO 2 and SO 3 showed a mitigating effect on mercury chlorination to some degree, depending on the concentrations of SO 2 and SO 3 , by competing against HCl for SCR adsorption sites. High levels of acid gases of HCl (50 ppm), SO 2 (2000 ppm), and SO 3 (50 ppm) in the flue gas deteriorate mercury adsorption on the SCR catalyst. (author)

Determination of Adsorption Capacity and Kinetics of Amidoxime-Based Uranium Adsorbent Braided Material in Unfiltered Seawater Using a Flume Exposure System

International Nuclear Information System (INIS)

Gill, Gary A.; Kuo, Li-Jung; Strivens, Jonathan E.; Park, Jiyeon; Bonheyo, George T.; Jeters, Robert T.; Schlafer, Nicholas J.; Wood, Jordana R.

2015-01-01

PNNL has developed a recirculating flume system for exposing braided adsorbent material to natural seawater under realistic temperature and flow-rate exposure conditions. The flumes are constructed of transparent acrylic material; they allow external light to pass into the flumes and permit photosynthetic growth of naturally present marine organisms (biofouling). Because the system consists of two flumes, replicate experiments can be conducted in which one of the flumes can be manipulated relative to the other. For example, one flume can be darkened to eliminate light exposure by placing a black tarp over the flume such that dark/light experiments can be conducted. Alternatively, two different braided adsorbents can be exposed simultaneously with no potential cross contamination issues. This report describes the first use of the PNNL flume system to study the impact of biofouling on adsorbent capacity. Experiments were conducted with the ORNL AI8 braided adsorbent material in light-exposed and darkened flumes for a 42-day exposure experiment. The major objective of this effort is to develop a system for the exposure of braided adsorbent material to unfiltered seawater, and to demonstrate the system by evaluating the performance of adsorption material when it is exposed to natural marine biofouling as it would be when the technology is used in the marine environment. Exposures of amidoxime-based polymeric braid adsorbents prepared by Oak Ridge Natural Laboratory (ORNL) were exposed to ambient seawater at 20°C in a flume system. Adsorption kinetics and adsorption capacity were assessed using time series determinations of uranium adsorption and one-site ligand saturation modeling. Biofouling in sunlight surface seawater has the potential to significantly add substantial biogenic mass to adsorption material when it is exposed for periods greater than 21 days. The observed biomass increase in the light flume was approximately 80% of the adsorbent mass after 42 days

Determination of Adsorption Capacity and Kinetics of Amidoxime-Based Uranium Adsorbent Braided Material in Unfiltered Seawater Using a Flume Exposure System

Energy Technology Data Exchange (ETDEWEB)

Gill, Gary A. [Pacific Northwest National Lab. (PNNL), Sequim, WA (United States). Marine Sciences Lab.; Kuo, Li-Jung [Pacific Northwest National Lab. (PNNL), Sequim, WA (United States). Marine Sciences Lab.; Strivens, Jonathan E. [Pacific Northwest National Lab. (PNNL), Sequim, WA (United States). Marine Sciences Lab.; Park, Jiyeon [Pacific Northwest National Lab. (PNNL), Sequim, WA (United States). Marine Sciences Lab.; Bonheyo, George T. [Pacific Northwest National Lab. (PNNL), Sequim, WA (United States). Marine Sciences Lab.; Jeters, Robert T. [Pacific Northwest National Lab. (PNNL), Sequim, WA (United States). Marine Sciences Lab.; Schlafer, Nicholas J. [Pacific Northwest National Lab. (PNNL), Sequim, WA (United States). Marine Sciences Lab.; Wood, Jordana R. [Pacific Northwest National Lab. (PNNL), Sequim, WA (United States). Marine Sciences Lab.

2015-08-31

PNNL has developed a recirculating flume system for exposing braided adsorbent material to natural seawater under realistic temperature and flow-rate exposure conditions. The flumes are constructed of transparent acrylic material; they allow external light to pass into the flumes and permit photosynthetic growth of naturally present marine organisms (biofouling). Because the system consists of two flumes, replicate experiments can be conducted in which one of the flumes can be manipulated relative to the other. For example, one flume can be darkened to eliminate light exposure by placing a black tarp over the flume such that dark/light experiments can be conducted. Alternatively, two different braided adsorbents can be exposed simultaneously with no potential cross contamination issues. This report describes the first use of the PNNL flume system to study the impact of biofouling on adsorbent capacity. Experiments were conducted with the ORNL AI8 braided adsorbent material in light-exposed and darkened flumes for a 42-day exposure experiment. The major objective of this effort is to develop a system for the exposure of braided adsorbent material to unfiltered seawater, and to demonstrate the system by evaluating the performance of adsorption material when it is exposed to natural marine biofouling as it would be when the technology is used in the marine environment. Exposures of amidoxime-based polymeric braid adsorbents prepared by Oak Ridge Natural Laboratory (ORNL) were exposed to ambient seawater at 20°C in a flume system. Adsorption kinetics and adsorption capacity were assessed using time series determinations of uranium adsorption and one-site ligand saturation modeling. Biofouling in sunlight surface seawater has the potential to significantly add substantial biogenic mass to adsorption material when it is exposed for periods greater than 21 days. The observed biomass increase in the light flume was approximately 80% of the adsorbent mass after 42 days

Assessment of the adsorptive capacity of the Kaolin deposit targeting its use on the removal of colors in aqueous solution

International Nuclear Information System (INIS)

Matos, S.C.; Hildebrando, E.A.

2016-01-01

The Amazonic region has large and valuable kaolin deposits. The state of Para by itself comprises three large industries which process kaolin. It has been noticed that the waste resulting from the processing of kaolin is rich in silico-aluminate, presenting potential in adsorption processes. Thus, this research's objective is to assess the kaolin waste produced during the processing phase, aiming at its application as low cost adsorbent material. For that, the kaolin waste has been characterized by X-ray diffraction and chemical analysis (XRF), and then sieved and calcined at 700 ° C, being then subjected to the adsorption process and observed qualitatively its capacity of retention by methylene blue (AM). Preliminary results show that the kaolin waste has satisfactory adsorption capacity at concentrations of up to 50.0 mg / MP, demonstrating the potential that it be used in the removal of dyes in wastewater treatment. (author)

Effective Microporosity for Enhanced Adsorption Capacity of Cr (VI) from Dilute Aqueous Solution: Isotherm and Kinetics

OpenAIRE

Lloyd Mukosha; Maurice S. Onyango; Aoyi Ochieng; John Siame

2017-01-01

The adsorbent pore structure significant to enhanced adsorption capacity of Cr (VI) from dilute aqueous solution is evaluated. As reference, low-cost micro-mesoporous activated carbon (AC) of high basicity, mesoporosity centred about 2.4 nm, and effective microporosity centred about 0.9 nm was tested for removal of Cr (VI) from dilute aqueous solution in batch mode. At pH 2 the low-cost AC exhibited highly improved Langmuir Cr (VI) capacity of 115 mg/g which was competitive to high performanc...

Characterization of the binding capacity of mercurial species in Lactobacillus strains.

Science.gov (United States)

Alcántara, Cristina; Jadán-Piedra, Carlos; Vélez, Dinoraz; Devesa, Vicenta; Zúñiga, Manuel; Monedero, Vicente

2017-12-01

Metal sequestration by bacteria has been proposed as a strategy to counteract metal contamination in foodstuffs. Lactobacilli can interact with metals, although studies with important foodborne metals such as inorganic [Hg(II)] or organic (CH 3 Hg) mercury are lacking. Lactobacilli were evaluated for their potential to bind these contaminants and the nature of the interaction was assessed by the use of metal competitors, chemical and enzymatical treatments, and mutants affected in the cell wall structure. Lactobacillus strains efficiently bound Hg(II) and CH 3 Hg. Mercury binding by Lactobacillus casei BL23 was independent of cell viability. In BL23, both forms of mercury were cell wall bound. Their interaction was not inhibited by cations and it was resistant to chelating agents and protein digestion. Lactobacillus casei mutants affected in genes involved in the modulation of the negative charge of the cell wall anionic polymer lipoteichoic acid showed increased mercury biosorption. In these mutants, mercury toxicity was enhanced compared to wild-type bacteria. These data suggest that lipoteichoic acid itself or the physicochemical characteristics that it confers to the cell wall play a major role in mercury complexation. This is the first example of the biosorption of Hg(II) and CH 3 Hg in lactobacilli and it represents a first step towards their possible use as agents for diminishing mercury bioaccessibility from food at the gastrointestinal tract. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Adsorption characteristics of siloxanes in landfill gas by the adsorption equilibrium test

International Nuclear Information System (INIS)

Nam, Sangchul; Namkoong, Wan; Kang, Jeong-Hee; Park, Jin-Kyu; Lee, Namhoon

2013-01-01

Highlights: • Equilibrium test was attempted to evaluate adsorption characteristics of siloxane. • L2 had higher removal efficiency in carbon compared to noncarbon adsorbents. • Total adsorption capacity of siloxane was 300 mg/g by coal activated carbon. • Adsorption characteristics rely on size of siloxane molecule and adsorbent pore. • Conversion of siloxane was caused by adsorption of noncarbon adsorbents. - Abstract: Due to the increase in energy cost by constantly high oil prices and the obligation to reduce greenhouse effect gases, landfill gas is frequently used as an alternative energy source for producing heat and electricity. Most of landfill gas utility facilities, however, are experiencing problems controlling siloxanes from landfill gas as their catalytic oxidizers are becoming fouled by silicon dioxide dust. To evaluate adsorption characteristics of siloxanes, an adsorption equilibrium test was conducted and parameters in the Freundlich and Langmuir isotherms were analyzed. Coconut activated carbon (CA1), coal activated carbon (CA2), impregnated activated carbon (CA3), silicagel (NCA1), and activated alumina (NCA2) were used for the adsorption of the mixed siloxane which contained hexamethyldisiloxane (L2), octamethylcyclotetrasiloxane (D4), and decamethylcyclopentasiloxane (D5). L2 had higher removal efficiency in noncarbon adsorbents compared to carbon adsorbents. The application of Langmuir and Freundlich adsorption isotherm demonstrated that coconut based CA1 and CA3 provided higher adsorption capacity on L2. And CA2 and NCA1 provided higher adsorption capacity on D4 and D5. Based on the experimental results, L2, D4, and D5 were converted by adsorption and desorption in noncarbon adsorbents. Adsorption affinity of siloxane is considered to be affect by the pore size distribution of the adsorbents and by the molecular size of each siloxane

Adsorption characteristics of siloxanes in landfill gas by the adsorption equilibrium test

Energy Technology Data Exchange (ETDEWEB)

Nam, Sangchul; Namkoong, Wan [Department of Environmental Engineering, Konkuk University, Hwayang-Dong, Gwangjin-Gu, Seoul 143-701 (Korea, Republic of); Kang, Jeong-Hee; Park, Jin-Kyu [Department of Environmental Engineering, Anyang University, Anyang 5-Dong, Manan-Gu, Anyang-Si, Gyeonggi-Do 430-714 (Korea, Republic of); Lee, Namhoon, E-mail: nhlee@anyang.ac.kr [Department of Environmental Engineering, Anyang University, Anyang 5-Dong, Manan-Gu, Anyang-Si, Gyeonggi-Do 430-714 (Korea, Republic of)

2013-10-15

Highlights: • Equilibrium test was attempted to evaluate adsorption characteristics of siloxane. • L2 had higher removal efficiency in carbon compared to noncarbon adsorbents. • Total adsorption capacity of siloxane was 300 mg/g by coal activated carbon. • Adsorption characteristics rely on size of siloxane molecule and adsorbent pore. • Conversion of siloxane was caused by adsorption of noncarbon adsorbents. - Abstract: Due to the increase in energy cost by constantly high oil prices and the obligation to reduce greenhouse effect gases, landfill gas is frequently used as an alternative energy source for producing heat and electricity. Most of landfill gas utility facilities, however, are experiencing problems controlling siloxanes from landfill gas as their catalytic oxidizers are becoming fouled by silicon dioxide dust. To evaluate adsorption characteristics of siloxanes, an adsorption equilibrium test was conducted and parameters in the Freundlich and Langmuir isotherms were analyzed. Coconut activated carbon (CA1), coal activated carbon (CA2), impregnated activated carbon (CA3), silicagel (NCA1), and activated alumina (NCA2) were used for the adsorption of the mixed siloxane which contained hexamethyldisiloxane (L2), octamethylcyclotetrasiloxane (D4), and decamethylcyclopentasiloxane (D5). L2 had higher removal efficiency in noncarbon adsorbents compared to carbon adsorbents. The application of Langmuir and Freundlich adsorption isotherm demonstrated that coconut based CA1 and CA3 provided higher adsorption capacity on L2. And CA2 and NCA1 provided higher adsorption capacity on D4 and D5. Based on the experimental results, L2, D4, and D5 were converted by adsorption and desorption in noncarbon adsorbents. Adsorption affinity of siloxane is considered to be affect by the pore size distribution of the adsorbents and by the molecular size of each siloxane.

Highly Efficient Adsorption of Copper Ions by a PVP-Reduced Graphene Oxide Based On a New Adsorptions Mechanism

Institute of Scientific and Technical Information of China (English)

Yongji Zhang; HuiJuan Chi; WenHui Zhang; Youyi Sun; Qing Liang; Yu Gu; Riya Jing

2014-01-01

Polyvinylpyrrolidone-reduced graphene oxide was prepared by modified hummers method and was used as adsorbent for removing Cu ions from wastewater. The effects of contact time and ions concentration on adsorption capacity were examined. The maximum adsorption capacity of 1689 mg/g was observed at an initial p H value of 3.5 after agitating for 10 min. It was demonstrated that polyvinylpyrrolidone-reduced graphene oxide had a huge adsorption capacity for Cu ions, which was 10 times higher than maximal value reported in previous works. The adsorption mechanism was also discussed by density functional theory. It demonstrates that Cu ions are attracted to surface of reduced graphene oxide by C atoms in reduced graphene oxide modified by polyvinylpyrrolidone through physisorption processes, which may be responsible for the higher adsorption capacity. Our results suggest that polyvinylpyrrolidone-reduced graphene oxide is an effective adsorbent for removing Cu ions in wastewater. It also provides a new way to improve the adsorption capacity of reduced graphene oxide for dealing with the heavy metal ion in wastewater.

Review of technologies for mercury removal from flue gas from cement production processes

DEFF Research Database (Denmark)

Zheng, Yuanjing; Jensen, Anker Degn; Windelin, Christian

2012-01-01

sources of mercury in the cement kiln flue gas. Cement plants are quite different from power plants and waste incinerators regarding the flue gas composition, temperature, residence time, and material circulation. Cement kiln systems have some inherent ability to retain mercury in the solid materials due...... to the adsorption of mercury on the solids in the cold zone. However, recirculation of the kiln dust to the kiln will cause release of the captured mercury. The mercury chemistry in cement kiln systems is complicated and knowledge obtained from power plants and incinerators cannot be directly applied in cement...

Density functional investigation of mercury and arsenic adsorption on nitrogen doped graphene decorated with palladium clusters: A promising heavy metal sensing material in farmland

Energy Technology Data Exchange (ETDEWEB)

Zhao, Chunjiang, E-mail: zhaocj_nercita@163.com [National Engineering Research Center for Information Technology in Agriculture, Beijing 100097 (China); Beijing Research Center for Information Technology in Agriculture, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100097 (China); Key Laboratory for Information Technologies in Agriculture, Ministry of Agriculture, Beijing100097 (China); Wu, Huarui, E-mail: wuhrnercita@163.com [National Engineering Research Center for Information Technology in Agriculture, Beijing 100097 (China); Beijing Research Center for Information Technology in Agriculture, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100097 (China); Key Laboratory for Information Technologies in Agriculture, Ministry of Agriculture, Beijing100097 (China)

2017-03-31

Highlights: • PNG can be acted as micro-sensor for monitoring heavy metal in agriculture. • The most favorable adsorption site of Pd atom or cluster on PNG is the vacancy site. • The Pd atom or cluster enhance the reactivity of PNG toward Hg and AsH{sub 3} adsorption. • The efficiency of a sorbent can be tuned by tailoring the ε{sub d} of adsorbed metals. - Abstract: Density functional theory calculations are carried out to study the adsorption of mercury and arsenic on Pd{sub n} (n = 1–6) supported on pyridine-like nitrogen doped graphene (PNG). Owing to the promising sensitivity in trace amounts of atoms or molecules, PNG can be acted as micro-sensor for sensing heavy metals in agriculture soils. Through the analyses of structural and electronic properties of pristine PNG and Pd atom decorated PNG, we find that the most favorable adsorption site for Pd atom is the vacancy site. The analyses of structural and electronic properties reveal that the Pd atom or clusters can enhance the reactivity for Hg and AsH{sub 3} adsorption on PNG. The adsorption ability of Hg on Pd{sub n} decorated PNG is found to be related to the d-band center (ε{sub d}) of the Pd{sub n}, in which the closer ε{sub d} of Pd{sub n} to the Fermi level, the higher adsorption strength for Hg on Pd{sub n} decorated PNG. Moreover, the charge transfer between Pd{sub n} and arsenic may constitute arsenic adsorption on Pd{sub n} decorated PNG. Further design of highly efficient carbon based sorbents for heavy metals removal should be focused on tailoring ε{sub d} of adsorbed metals.

A one-step thermal decomposition method to prepare anatase TiO{sub 2} nanosheets with improved adsorption capacities and enhanced photocatalytic activities

Energy Technology Data Exchange (ETDEWEB)

Li, Wenting; Shang, Chunli; Li, Xue, E-mail: chm_lix@ujn.edu.cn

2015-12-01

Highlights: • Anatase TiO{sub 2} nanosheets (NSs) with high surface area have been prepared. • Only one type of surfactant, oleylamine (OM), is used as capping agents. • TiO{sub 2} NSs possess high adsorption capacities MB and high photocatalytic activity. - Abstract: Anatase TiO{sub 2} nanosheets (NSs) with high surface area have been prepared via a one-step thermal decomposition of titanium tetraisopropoxide (TTIP) in oleylamine (OM), and their adsorption capacities and photocatalytic activities are investigated by using methylene blue (MB) and methyl orange (MO) as model pollutants. During the synthesis procedure, only one type of surfactant, oleylamine (OM), is used as capping agents and no other solvents are added. Structure and properties of the TiO{sub 2} NSs were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), N{sub 2} adsorption analysis, UV–vis spectrum, X-ray photoelectron spectroscopy (XPS) and Photoluminescence (PL) methods. The results indicate that the TiO{sub 2} NSs possess high surface area up to 378 m{sup 2} g{sup −1}. The concentration of capping agents is found to be a key factor controlling the morphology and crystalline structure of the product. Adsorption and photodegradation experiments reveal that the prepared TiO{sub 2} NSs possess high adsorption capacities of model pollutants MB and high photocatalytic activity, showing that TiO{sub 2} NSs can be used as efficient pollutant adsorbents and photocatalytic degradation catalysts of MB in wastewater treatment.

Kinetic and thermodynamic studies on the adsorption of heavy metals from aqueous solution by melanin nanopigment obtained from marine source: Pseudomonas stutzeri.

Science.gov (United States)

Manirethan, Vishnu; Raval, Keyur; Rajan, Reju; Thaira, Harsha; Balakrishnan, Raj Mohan

2018-05-15

The difficulty in removal of heavy metals at concentrations below 10 mg/L has led to the exploration of efficient adsorbents for removal of heavy metals. The adsorption capacity of biosynthesized melanin for Mercury (Hg(II)), Chromium (Cr(VI)), Lead (Pb(II)) and Copper (Cu(II)) was investigated at different operating conditions like pH, time, initial concentration and temperature. The heavy metals adsorption process was well illustrated by the Lagergren's pseudo-second-order kinetic model and the equilibrium data fitted excellently to Langmuir isotherm. Maximum adsorption capacity obtained from Langmuir isotherm for Hg(II) was 82.4 mg/g, Cr(VI) was 126.9 mg/g, Pb(II) was 147.5 mg/g and Cu(II) was 167.8 mg/g. The thermodynamic parameters revealed that the adsorption of heavy metals on melanin is favorable, spontaneous and endothermic in nature. Binding of heavy metals on melanin surface was proved by Fourier Transform Infrared Spectroscopy (FT-IR) and X-ray Photoelectron Spectroscopy (XPS). Contemplating the results, biosynthesized melanin can be a potential adsorbent for efficient removal of Hg(II), Cr(VI), Pb(II) and Cu(II) ions from aqueous solution. Copyright © 2018 Elsevier Ltd. All rights reserved.

Mercury nano-trap for effective and efficient removal of mercury(II) from aqueous solution

Science.gov (United States)

Li, Baiyan; Zhang, Yiming; Ma, Dingxuan; Shi, Zhan; Ma, Shengqian

2014-11-01

Highly effective and highly efficient decontamination of mercury from aqueous media remains a serious task for public health and ecosystem protection. Here we report that this task can be addressed by creating a mercury ‘nano-trap’ as illustrated by functionalizing a high surface area and robust porous organic polymer with a high density of strong mercury chelating groups. The resultant porous organic polymer-based mercury ‘nano-trap’ exhibits a record-high saturation mercury uptake capacity of over 1,000 mg g-1, and can effectively reduce the mercury(II) concentration from 10 p.p.m. to the extremely low level of smaller than 0.4 p.p.b. well below the acceptable limits in drinking water standards (2 p.p.b.), and can also efficiently remove >99.9% mercury(II) within a few minutes. Our work therefore presents a new benchmark for mercury adsorbent materials and provides a new perspective for removing mercury(II) and also other heavy metal ions from contaminated water for environmental remediation.

Amine-tethered solid adsorbents coupling high adsorption capacity and regenerability for CO2 capture from ambient air.

Science.gov (United States)

Choi, Sunho; Gray, McMahan L; Jones, Christopher W

2011-05-23

Silica supported poly(ethyleneimine) (PEI) materials are prepared via impregnation and demonstrated to be promising adsorbents for CO(2) capture from ultra-dilute gas streams such as ambient air. A prototypical class 1 adsorbent, containing 45 wt% PEI (PEI/silica), and two new modified PEI-based aminosilica adsorbents, derived from PEI modified with 3-aminopropyltrimethoxysilane (A-PEI/silica) or tetraethyl orthotitanate (T-PEI/silica), are prepared and characterized by using thermogravimetric analysis and FTIR spectroscopy. The modifiers are shown to enhance the thermal stability of the polymer-oxide composites, leading to higher PEI decomposition temperatures. The modified adsorbents present extremely high CO(2) adsorption capacities under conditions simulating ambient air (400 ppm CO(2) in inert gas), exceeding 2 mol(CO (2)) kg(sorbent)(-1), as well as enhanced adsorption kinetics compared to conventional class 1 sorbents. The new adsorbents show excellent stability in cyclic adsorption-desorption operations, even under dry conditions in which aminosilica adsorbents are known to lose capacity due to urea formation. Thus, the adsorbents of this type can be considered promising materials for the direct capture of CO(2) from ultra-dilute gas streams such as ambient air. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Mercury Detection with Gold Nanoparticles: Investigating Fundamental Phenomena and Expanding Applications

Science.gov (United States)

Crosby, Jeffrey Scott

Mercury is a pollutant of grave concern with well documented neurological and developmental health impacts. Better sensing methodology would improve detection and control of mercury and thus reduce its health burden. Gold nanoparticles provide a sensing medium with potential advantages in sensitivity, selectivity, robustness, and cost over established techniques. Mercury readily adsorbs onto the surface of the gold changing the localized surface plasmon resonance which is measured as a shift in the peak optical absorbance wavelength. This shift is dependent on the mercury concentration and predictable with classical electromagnetism. This work investigates some of the fundamental relationships driving sensor response. The effects of mass transfer and surface kinetics on mercury/gold nanoparticle adsorption are determined with analytical models and experimental results based on impinging flow geometry. To decouple mass transfer and surface kinetics adsorption, electrical analogy models are constructed and fit to the experimental data. The models can account for variations in flow conditions and surface coatings on the nanoparticles. These models are generalizable to other systems. Results from these fundamental investigations are used to improve and extend sensor performance. The time response or collection efficiency is optimized depending on system requirements. Using the knowledge gained, the applicability of gold nanoparticle mercury sensors is extended to a fiber optic based system and aqueous detection. Nanorods deposited on the surface of a fiber optic cable have a linear response with concentration and are able to detect mercury down to 1.0 mug/m3. The modification of an established oxidation/reduction scheme for use with the sensor allows for the detection of ionic and organic mercury from water samples which ordinarily would not be reactive with gold nanoparticles. The aqueous sensor was able to detect mercury below the EPA's drinking water limit.

Pore Structure and Fluoride Ion Adsorption Characteristics of Zr (IV) Surface-Immobilized Resin Prepared Using Polystyrene as a Porogen

Science.gov (United States)

Mizuki, Hidenobu; Ito, Yudai; Harada, Hisashi; Uezu, Kazuya

Zr(IV) surface-immobilized resins for removal of fluoride ion were prepared by surface template polymerization using polystyrene as a porogen. At polymerization, polystyrene was added in order to increase mesopores (2-50 nm) and macropore (>50 nm) with large macropores (around 300 nm) formed with internal aqueous phase of W⁄O emulsion. The pore structure of Zr(IV) surface-immobilized resins was evaluated by measuring specific surface area, pore volume, and pore size distribution with volumetric adsorption measurement instrument and mercury porosimeter. The adsorption isotherms were well fitted by Langmuir equation. The removal of fluoride was also carried out with column method. Zr(IV) surface-immobilized resins, using 10 g⁄L polystyrene in toluene at polymerization, possessed higher volume of not only mesopores and macropores but also large macropores. Furethermore, by adding the polystyrene with smaller molecular size, the pore volume of mesopores, macropores and large macropores was significantly increased, and the fluoride ion adsorption capacity and the column utilization also increased.

Characterization of the cation-binding capacity of a potassium-adsorption filter used in red blood cell transfusion.

Science.gov (United States)

Suzuki, Takao; Muto, Shigeaki; Miyata, Yukio; Maeda, Takao; Odate, Takayuki; Shimanaka, Kimio; Kusano, Eiji

2015-06-01

A K(+) -adsorption filter was developed to exchange K(+) in the supernatant of stored irradiated red blood cells with Na(+) . To date, however, the filter's adsorption capacity for K(+) has not been fully evaluated. Therefore, we characterized the cation-binding capacity of this filter. Artificial solutions containing various cations were continuously passed through the filter in 30 mL of sodium polystyrene sulfonate at 10 mL/min using an infusion pump at room temperature. The cation concentrations were measured before and during filtration. When a single solution containing K(+) , Li(+) , H(+) , Mg(2+) , Ca(2+) , or Al(3+) was continuously passed through the filter, the filter adsorbed K(+) and the other cations in exchange for Na(+) in direct proportion to the valence number. The order of affinity for cation adsorption to the filter was Ca(2+) >Mg(2+) >K(+) >H(+) >Li(+) . In K(+) -saturated conditions, the filter also adsorbed Na(+) . After complete adsorption of these cations on the filter, their concentration in the effluent increased in a sigmoidal manner over time. Cations that were bound to the filter were released if a second cation was passed through the filter, despite the different affinities of the two cations. The ability of the filter to bind cations, especially K(+) , should be helpful when it is used for red blood cell transfusion at the bedside. The filter may also be useful to gain a better understanding of the pharmacological properties of sodium polystyrene sulfonate. © 2015 The Authors. Therapeutic Apheresis and Dialysis © 2015 International Society for Apheresis.

Trace-level mercury removal from surface water

International Nuclear Information System (INIS)

Klasson, K.T.; Bostick, D.T.

1998-01-01

Many sorbents have been developed for the removal of mercury and heavy metals from waters; however, most of the data published thus far do not address the removal of mercury to the target levels represented in this project. The application to which these sorbents are targeted for use is the removal of mercury from microgram-per-liter levels to low nanogram-per-liter levels. Sorbents with thiouronium, thiol, amine, sulfur, and proprietary functional groups were selected for these studies. Mercury was successfully removed from surface water via adsorption onto Ionac SR-4 and Mersorb resins to levels below the target goal of 12 ng/L in batch studies. A thiol-based resin performed the best, indicating that over 200,000 volumes of water could be treated with one volume of resin. The cost of the resin is approximately $0.24 per 1,000 gal of water

Evaluation of physical properties and adsorption capacity of regenerated granular activated carbons (GACs)

International Nuclear Information System (INIS)

Chae, Seon-Ha; Kim, Seong-Su; Park, No-Suk; Jeong, Woochang

2013-01-01

The objectives of this study were to evaluate the variation in physical properties and investigate the adsorption capacity after regeneration of granular activated carbon (GAC). A correlation analysis was conducted to examine the relationship between the iodide number and loss rate. The experimental results showed that the loss rate of regenerated carbon should be related to the usage time of GAC. Physical properties including the effective size and uniformity coefficient were similar to those of virgin GAC. This result indicates that the function of GAC as an adsorption medium may be recovered completely. Although the iodine number and specific surface area of the regenerated GAC were smaller than those of virgin GAC, the cumulative pore volume of the former was larger. The removal efficiency of organic matter from the regenerated GAC column was equal to or slightly higher than that from the virgin GAC column. Consequently, regeneration may increase the number of mesopores which are responsible for the removal of organic matter

Evaluation of physical properties and adsorption capacity of regenerated granular activated carbons (GACs)

Energy Technology Data Exchange (ETDEWEB)

Chae, Seon-Ha; Kim, Seong-Su; Park, No-Suk [Korea Water Resources Corporation, Daejeon (Korea, Republic of); Jeong, Woochang [Kyungnam University, Changwon (Korea, Republic of)

2013-04-15

The objectives of this study were to evaluate the variation in physical properties and investigate the adsorption capacity after regeneration of granular activated carbon (GAC). A correlation analysis was conducted to examine the relationship between the iodide number and loss rate. The experimental results showed that the loss rate of regenerated carbon should be related to the usage time of GAC. Physical properties including the effective size and uniformity coefficient were similar to those of virgin GAC. This result indicates that the function of GAC as an adsorption medium may be recovered completely. Although the iodine number and specific surface area of the regenerated GAC were smaller than those of virgin GAC, the cumulative pore volume of the former was larger. The removal efficiency of organic matter from the regenerated GAC column was equal to or slightly higher than that from the virgin GAC column. Consequently, regeneration may increase the number of mesopores which are responsible for the removal of organic matter.

Thermodynamics of adsorption of dithiocarbamates at the hanging mercury drop.

Science.gov (United States)

Giannakopoulos, Evangelos; Deligiannakis, Yiannis

2007-02-27

Two dimethyldithiocarbamate (DMDTC) pesticides, thiram and ziram, are adsorbed onto a Hg drop via an entropically driven process. The adsorption isotherms are described by the Frumkin equation. For both molecules, the adsorption is characterized by a nonlinear pseudosigmoid temperature dependence of the Gibbs free energy. For the temperature range of 273-313 K, DeltaGADS varies between -43.4 and -56.71 kJ/mol for thiram and -42.60 and -55.67 kJ/mol for ziram. This variation of DeltaGADS reveals that the adsorption strength is increased at higher temperatures. During the adsorption of either molecule, strong lateral interactions are developed between neighboring adsorbates, which are severely weakened as the temperature increases. A unified reaction scheme is suggested for both ziram and thiram that predicts the formation and adsorption of a surface complex, (DMDTC)2Hg. In the case of thiram, two DMDTC molecules are formed by the cleavage of the disulfide S-S bond near the Hg electrode. The thermodynamic and structural parameters reveal that there are two limiting thermodynamic regimes for the adsorbed (DMDTC)2Hg species that originate from two limiting adsorption conformations of the adsorbates on the Hg surface. A transition occurs between these two conformations at temperatures in the region of 285-295 K. This transition is accompanied by large entropic and enthalpic changes.

Reservoir capacity estimates in shale plays based on experimental adsorption data

Science.gov (United States)

Ngo, Tan

from different measurement techniques using representative fluids (such as CH4 and CO2) at elevated pressures, and the adsorbed density can range anywhere between the liquid and the solid state of the adsorbate. Whether these discrepancies are associated with the inherent heterogeneity of mudrocks and/or with poor data quality requires more experiments under well-controlled conditions. Nevertheless, it has been found in this study that methane GIP estimates can vary between 10-45% and 10-30%, respectively, depending on whether the free or the total amount of gas is considered. Accordingly, CO2 storage estimates range between 30-90% and 15-50%, due to the larger adsorption capacity and gas density at similar pressure and temperature conditions. A manometric system has been designed and built that allows measuring the adsorption of supercritical fluids in microporous materials. Preliminary adsorption tests have been performed using a microporous 13X zeolite and CO 2 as an adsorbing gas at a temperature of 25oC and 35oC and at pressures up to 500 psi. Under these conditions, adsorption is quantified with a precision of +/- 3%. However, relative differences up to 15-20% have been observed with respect to data published in the literature on the same adsorbent and at similar experimental conditions. While it cannot be fully explained with uncertainty analysis, this discrepancy can be reduced by improving experiment practice, thus including the application of a higher adsorbent's regeneration temperature, of longer equilibrium times and of a careful flushing of the system between the various experimental steps. Based on the results on 13X zeolite, virtual tests have been conducted to predict the performance of the manometric system to measure adsorption on less adsorbing materials, such as mudrocks. The results show that uncertainties in the estimated adsorbed amount are much more significant in shale material and they increase with increasing pressure. In fact, relative

[Removal Characteristics of Elemental Mercury by Mn-Ce/molecular Sieve].

Science.gov (United States)

Tan, Zeng-qiang; Niu, Guo-ping; Chen, Xiao-wen; An, Zhen

2015-06-01

The impregnation method was used to support molecular sieve with active manganese and cerium components to obtain a composite molecular sieve catalyst. The mercury removal performance of the catalyst was studied with a bench-scale setup. XPS analysis was used to characterize the sample before and after the modification in order to study the changes in the active components of the catalyst prepared. The results showed that the catalyst carrying manganese and cerium components had higher oxidation ability of elemental mercury in the temperature range of 300 degrees C - 450 degrees C, especially at 450 degrees C, the oxidation efficiency of elemental mercury was kept above 80%. The catalyst had more functional groups that were conducive to the oxidation of elemental mercury, and the mercury removal mainly depended on the chemical adsorption. The SO2 and NO in flue gas could inhibit the oxidation of elemental mercury to certain extent.

Mercury(II) and methyl mercury speciation on Streptococcus pyogenes loaded Dowex Optipore SD-2

International Nuclear Information System (INIS)

Tuzen, Mustafa; Uluozlu, Ozgur Dogan; Karaman, Isa; Soylak, Mustafa

2009-01-01

A solid phase extraction procedure based on speciation of mercury(II) and methyl mercury on Streptococcus pyogenes immobilized on Dowex Optipore SD-2 has been established. Selective and sequential elution with 0.1 mol L -1 HCl for methyl mercury and 2 mol L -1 HCl for mercury(II) were performed at pH 8. The determination of mercury levels was performed by cold vapour atomic absorption spectrometry (CVAAS). Optimal analytical conditions including pH, amounts of biosorbent, sample volumes, etc., were investigated. The influences of the some alkaline and earth alkaline ions and some transition metals on the recoveries were also investigated. The capacity of biosorbent for mercury(II) and methyl mercury was 4.8 and 3.4 mg g -1 . The detection limit (3 sigma) of the reagent blank for mercury(II) and methyl mercury was 2.1 and 1.5 ng L -1 . Preconcentration factor was calculated as 25. The relative standard deviations of the procedure were below 7%. The validation of the presented procedure is performed by the analysis of standard reference material (NRCC-DORM 2 Dogfish Muscle). The procedure was successfully applied to the speciation of mercury(II) and methyl mercury in natural water and environmental samples.

Mercury(II) and methyl mercury speciation on Streptococcus pyogenes loaded Dowex Optipore SD-2

Energy Technology Data Exchange (ETDEWEB)

Tuzen, Mustafa, E-mail: m.tuzen@gmail.com [Gaziosmanpasa University, Faculty of Science and Arts, Chemistry Department, 60250 Tokat (Turkey); Uluozlu, Ozgur Dogan [Gaziosmanpasa University, Faculty of Science and Arts, Chemistry Department, 60250 Tokat (Turkey); Karaman, Isa [Gaziosmanpasa University, Faculty of Science and Arts, Biology Department, 60250 Tokat (Turkey); Soylak, Mustafa [Erciyes University, Faculty of Science and Arts, Chemistry Department, 38039 Kayseri (Turkey)

2009-09-30

A solid phase extraction procedure based on speciation of mercury(II) and methyl mercury on Streptococcus pyogenes immobilized on Dowex Optipore SD-2 has been established. Selective and sequential elution with 0.1 mol L{sup -1} HCl for methyl mercury and 2 mol L{sup -1} HCl for mercury(II) were performed at pH 8. The determination of mercury levels was performed by cold vapour atomic absorption spectrometry (CVAAS). Optimal analytical conditions including pH, amounts of biosorbent, sample volumes, etc., were investigated. The influences of the some alkaline and earth alkaline ions and some transition metals on the recoveries were also investigated. The capacity of biosorbent for mercury(II) and methyl mercury was 4.8 and 3.4 mg g{sup -1}. The detection limit (3 sigma) of the reagent blank for mercury(II) and methyl mercury was 2.1 and 1.5 ng L{sup -1}. Preconcentration factor was calculated as 25. The relative standard deviations of the procedure were below 7%. The validation of the presented procedure is performed by the analysis of standard reference material (NRCC-DORM 2 Dogfish Muscle). The procedure was successfully applied to the speciation of mercury(II) and methyl mercury in natural water and environmental samples.

Carbon dioxide adsorption in graphene sheets

Directory of Open Access Journals (Sweden)

Ashish Kumar Mishra

2011-09-01

Full Text Available Control over the CO2 emission via automobiles and industrial exhaust in atmosphere, is one of the major concerns to render environmental friendly milieu. Adsorption can be considered to be one of the more promising methods, offering potential energy savings compared to absorbent systems. Different carbon nanostructures (activated carbon and carbon nanotubes have attracted attention as CO2 adsorbents due to their unique surface morphology. In the present work, we have demonstrated the CO2 adsorption capacity of graphene, prepared via hydrogen induced exfoliation of graphitic oxide at moderate temperatures. The CO2 adsorption study was performed using high pressure Sieverts apparatus and capacity was calculated by gas equation using van der Waals corrections. Physical adsorption of CO2 molecules in graphene was confirmed by FTIR study. Synthesis of graphene sheets via hydrogen exfoliation is possible at large scale and lower cost and higher adsorption capacity of as prepared graphene compared to other carbon nanostructures suggests its possible use as CO2 adsorbent for industrial application. Maximum adsorption capacity of 21.6 mmole/g was observed at 11 bar pressure and room temperature (25 ºC.

Molecular simulation of methane adsorption characteristics on coal macromolecule

Science.gov (United States)

Yang, Zhiyuan; He, Xiaoxiao; Meng, Zhuoyue; Xue, Wenying

2018-02-01

In this paper, the molecular model of anthracite named Wender2 was selected to study the adsorption behaviour of single component CH4 and the competitive adsorption of CH4/CO2, CH4/H2O and CH4/N2. The molecular model of anthracite was established by molecular simulation software (Materials Studio 8.0), and Grand Canonical Monte Carlo (GCMC) simulations were carried out to investigate the single and binary component adsorption. The effects of pressure and temperature on the adsorption position, adsorption energy and adsorption capacity were mainly discussed. The results show that for the single component adsorption, the adsorption capacity of CH4 increases rapidly with the pressure ascending, and then tends to be stable after the first step. The low temperature is favourable for the adsorption of CH4, and the high temperature promotes desorption quantity of CH4 from the coal. Adsorbent molecules are preferentially adsorbed on the edge of coal macromolecules. The order of adsorption capacity of CH4/CO2, CH4/H2O and CH4/N2 in the binary component is H2O>CO2>CH4>N2. The change of pressure has little effect on the adsorption capacity of the adsorbent in the competitive adsorption, but it has a great influence on the adsorption capacity of the adsorbent, and there is a positive correlation between them.

A survey of topsoil arsenic and mercury concentrations across France.

Science.gov (United States)

Marchant, B P; Saby, N P A; Arrouays, D

2017-08-01

Even at low concentrations, the presence of arsenic and mercury in soils can lead to ecological and health impacts. The recent European-wide LUCAS Topsoil Survey found that the arsenic concentration of a large proportion of French soils exceeded a threshold which indicated that further investigation was required. A much smaller proportion of soils exceeded the corresponding threshold for mercury but the impacts of mining and industrial activities on mercury concentrations are not well understood. We use samples from the French national soil monitoring network (RMQS: Réseau de Mesures de la Qualité des Sols) to explore the variation of topsoil arsenic and mercury concentrations across mainland France at a finer spatial resolution than was reported by LUCAS Topsoil. We use geostatistical methods to map the expected concentrations of these elements in the topsoil and the probabilities that the legislative thresholds are exceeded. We find that, with the exception of some areas where the geogenic concentrations and soil adsorption capacities are very low, arsenic concentrations are generally larger than the threshold which indicates that further assessment of the area is required. The lower of two other guideline values indicating risks to ecology or health is exceeded in fewer than 5% of RMQS samples. These exceedances occur in localised hot-spots primarily associated with mining and mineralization. The probabilities of mercury concentrations exceeding the further assessment threshold value are everywhere less than 0.01 and none of the RMQS samples exceed either of the ecological and health risk thresholds. However, there are some regions with elevated concentrations which can be related to volcanic material, natural mineralizations and industrial contamination. These regions are more diffuse than the hot-spots of arsenic reflecting the greater volatility of mercury and therefore the greater ease with which it can be transported and redeposited. The maps provide a

Metal and proton adsorption capacities of natural and cloned Sphagnum mosses.

Science.gov (United States)

Gonzalez, Aridane G; Pokrovsky, Oleg S; Beike, Anna K; Reski, Ralf; Di Palma, Anna; Adamo, Paola; Giordano, Simonetta; Angel Fernandez, J

2016-01-01

Terrestrial mosses are commonly used as bioindicators of atmospheric pollution. However, there is a lack of standardization of the biomonitoring preparation technique and the efficiency of metal adsorption by various moss species is poorly known. This is especially true for in vitro-cultivated moss clones, which are promising candidates for a standardized moss-bag technique. We studied the adsorption of copper and zinc on naturally grown Sphagnum peat moss in comparison with in vitro-cultivated Sphagnum palustre samples in order to provide their physico-chemical characterization and to test the possibility of using cloned peat mosses as bioindicators within the protocol of moss-bag technique. We demonstrate that in vitro-grown clones of S. palustre exhibit acid-base properties similar to those of naturally grown Sphagnum samples, whereas the zinc adsorption capacity of the clones is approx. twice higher than that of the samples from the field. At the same time, the field samples adsorbed 30-50% higher amount of Cu(2+) compared to that of the clones. This contrast may be related to fine differences in the bulk chemical composition, specific surface area, morphological features, type and abundance of binding sites at the cell surfaces and in the aqueous solution of natural and cloned Sphagnum. The clones exhibited much lower concentration of most metal pollutants in their tissues relative to the natural samples thus making the former better indicators of low metal loading. Overall, in vitro-produced clones of S. palustre can be considered as an adequate, environmentally benign substitution for protected natural Sphagnum sp. samples to be used in moss-bags for atmospheric monitoring. Copyright © 2015 Elsevier Inc. All rights reserved.

Effect of oxygen potential on sulphur dioxide activation of oil sands fluid coke and characteristics of activated coke in mercury adsorption

International Nuclear Information System (INIS)

Morris, E.A.; Jia, C.Q.; Tong, S.

2007-01-01

A sulphur-impregnated activated carbon (SIAC) technology was modified for use in copper smelters in order to mitigate mercury and sulphur dioxide (SO 2 ) emissions. Elemental sulphur was captured as a co-product. The study examined the feasibility of reducing levels of SO 2 using fluid coke in the copper smelter flue. SIAC properties were optimized in order to capture vapour phase mercury. Raw fluid coke samples were used to measure SO 2 flow rates. Gas composition was varied to mimic concentrations found during normal operation of copper converters. Gas chromatography was used to analyze reactions products and to prove the hypothesis that mercury capacity is influenced by the oxygen potential of the activation gas due to changes in surface sulphur types developed from reduced sulphur species. Results of the study showed that oxygen levels at 5 per cent did not play a significant role in pore development. It was concluded that increased residence times contributed to reductions in SO 2 and elemental S yields. 13 refs., 1 tab., 7 figs

Effects of igneous intrusion on microporosity and gas adsorption capacity of coals in the Haizi Mine, China.

Science.gov (United States)

Jiang, Jingyu; Cheng, Yuanping

2014-01-01

This paper describes the effects of igneous intrusions on pore structure and adsorption capacity of the Permian coals in the Huaibei Coalfield, China. Twelve coal samples were obtained at different distances from a ~120 m extremely thick sill. Comparisons were made between unaltered and heat-affected coals using geochemical data, pore-fracture characteristics, and adsorption properties. Thermal alteration occurs down to ~1.3 × sill thickness. Approaching the sill, the vitrinite reflectance (R(o)) increased from 2.30% to 2.78%, forming devolatilization vacuoles and a fine mosaic texture. Volatile matter (VM) decreased from 17.6% to 10.0% and the moisture decreased from 3.0% to 1.6%. With decreasing distance to the sill, the micropore volumes initially increased from 0.0054 cm(3)/g to a maximum of 0.0146 cm(3)/g and then decreased to 0.0079 cm(3)/g. The results show that the thermal evolution of the sill obviously changed the coal geochemistry and increased the micropore volume and adsorption capacity of heat-affected coal (60-160 m from the sill) compared with the unaltered coals. The trap effect of the sill prevented the high-pressure gas from being released, forming gas pocket. Mining activities near the sill created a low pressure zone leading to the rapid accumulation of methane and gas outbursts in the Haizi Mine.

Effects of Igneous Intrusion on Microporosity and Gas Adsorption Capacity of Coals in the Haizi Mine, China

Science.gov (United States)

2014-01-01

This paper describes the effects of igneous intrusions on pore structure and adsorption capacity of the Permian coals in the Huaibei Coalfield, China. Twelve coal samples were obtained at different distances from a ~120 m extremely thick sill. Comparisons were made between unaltered and heat-affected coals using geochemical data, pore-fracture characteristics, and adsorption properties. Thermal alteration occurs down to ~1.3 × sill thickness. Approaching the sill, the vitrinite reflectance (R o) increased from 2.30% to 2.78%, forming devolatilization vacuoles and a fine mosaic texture. Volatile matter (VM) decreased from 17.6% to 10.0% and the moisture decreased from 3.0% to 1.6%. With decreasing distance to the sill, the micropore volumes initially increased from 0.0054 cm3/g to a maximum of 0.0146 cm3/g and then decreased to 0.0079 cm3/g. The results show that the thermal evolution of the sill obviously changed the coal geochemistry and increased the micropore volume and adsorption capacity of heat-affected coal (60–160 m from the sill) compared with the unaltered coals. The trap effect of the sill prevented the high-pressure gas from being released, forming gas pocket. Mining activities near the sill created a low pressure zone leading to the rapid accumulation of methane and gas outbursts in the Haizi Mine. PMID:24723841

Mercury species, selenium, metallothioneins and glutathione in two dolphins from the southeastern Brazilian coast: Mercury detoxification and physiological differences in diving capacity

International Nuclear Information System (INIS)

Kehrig, Helena A.; Hauser-Davis, Rachel A.; Seixas, Tercia G.; Pinheiro, Ana Beatriz; Di Beneditto, Ana Paula M.

2016-01-01

In the present study, the concentration of trace elements, total mercury (Hg) and selenium (Se) and mercury forms (MeHg, Hg inorg and HgSe) in the vulnerable coastal dolphins Pontoporia blainvillei and Sotalia guianensis were appraised and compared, using metallothioneins (MT) and glutathione (GSH) as biomarkers for trace element exposure. The trace element concentrations varied between muscle and liver tissues, with liver of all dolphin specimens showing higher Hg and Se concentrations than those found in muscle. Hg, MeHg and Hg inorg molar concentrations showed a clear increase with Se molar concentrations in the liver of both dolphins, and Se concentrations were higher than those of Hg on a molar basis. Se plays a relevant role in the detoxification of MeHg in the hepatic tissue of both dolphins, forming Hg-Se amorphous crystals in liver. In contrast, MT were involved in the detoxification process of Hg inorg in liver. GSH levels in P. blainvillei and S. guianensis muscle tissue suggest that these dolphins have different diving capacities. Muscle Hg concentrations were associated to this tripeptide, which protects dolphin cells against Hg stress. - Highlights: • Se aids in MeHg detoxification in dolphin liver, forming Hg-Se amorphous crystals. • MT was involved in liver Hg inorg detoxification and GSH was associated to muscle Hg. • Feeding habits seem to influence muscle GSH, suggesting different diving capacities. • MT, GSH and Se and Hg in different forms were investigated in two dolphin species. • Hepatic Hg, MeHg and Hg inorg increased with higher Se concentrations. - “Coastal dolphins showed Se-mediated detoxification of MeHg and MT-mediated detoxification of Hg inorg , while GSH suggests different diving capacities”.

Mercury emissions from municipal solid waste combustors

Energy Technology Data Exchange (ETDEWEB)

1993-05-01

This report examines emissions of mercury (Hg) from municipal solid waste (MSW) combustion in the United States (US). It is projected that total annual nationwide MSW combustor emissions of mercury could decrease from about 97 tonnes (1989 baseline uncontrolled emissions) to less than about 4 tonnes in the year 2000. This represents approximately a 95 percent reduction in the amount of mercury emitted from combusted MSW compared to the 1989 mercury emissions baseline. The likelihood that routinely achievable mercury emissions removal efficiencies of about 80 percent or more can be assured; it is estimated that MSW combustors in the US could prove to be a comparatively minor source of mercury emissions after about 1995. This forecast assumes that diligent measures to control mercury emissions, such as via use of supplemental control technologies (e.g., carbon adsorption), are generally employed at that time. However, no present consensus was found that such emissions control measures can be implemented industry-wide in the US within this time frame. Although the availability of technology is apparently not a limiting factor, practical implementation of necessary control technology may be limited by administrative constraints and other considerations (e.g., planning, budgeting, regulatory compliance requirements, etc.). These projections assume that: (a) about 80 percent mercury emissions reduction control efficiency is achieved with air pollution control equipment likely to be employed by that time; (b) most cylinder-shaped mercury-zinc (CSMZ) batteries used in hospital applications can be prevented from being disposed into the MSW stream or are replaced with alternative batteries that do not contain mercury; and (c) either the amount of mercury used in fluorescent lamps is decreased to an industry-wide average of about 27 milligrams of mercury per lamp or extensive diversion from the MSW stream of fluorescent lamps that contain mercury is accomplished.

Biosorption of mercury by capsulated and slime layer- forming Gram ...

African Journals Online (AJOL)

ONOS

2010-09-20

Sep 20, 2010 ... high negatively charged components, showed more than 1.5 fold increase as compared to capsulated ... Mercury is one of the most toxic heavy metals released in ... ion exchange, activated carbon adsorption and separation.

Study of algae's adsorption to uranium ion in water solution

International Nuclear Information System (INIS)

Du Yang; Qiu Yongmei; Dan Guiping; Zhang Dong; Lei Jiarong

2007-01-01

The adsorption efficiencies of the algae to uranium ion were determined at various pH, uranium ion concentrations, adsorption temperatures and the species of coexisted metal ions, and the effect of coexisted metal ion on the adsorption efficiency was researched. The experimental results at pH= 5-8 are as follows. 1) the adsorption capacity is a constant to be about 1.40 μg/g for the Yantai red alga and the sea spinach, and is changeable in the range of 1.03-2.23 μg/g with pH for the sea edible fungus; 2) for the algae the adsorption efficiency and adsorption capacity are related to uranium ion concentration, and the maximum adsorption efficiency and capacity is 95.8% and 65.4 μg/g, respectively; 3) the adsorption process for 24 h is not dependent on the temperature; 4) the effect of the species of coexisted metal ions on the adsorption capacity of uranium ion is various with the time during adsorption process. (authors)

Trace vanadium analysis by catalytic adsorptive stripping voltammetry using mercury-coated micro-wire and polystyrene-coated bismuth film electrodes

Energy Technology Data Exchange (ETDEWEB)

Dansby-Sparks, Royce; Chambers, James Q. [Department of Chemistry, University of Tennessee, Knoxville, TN 37996-1600 (United States); Xue Ziling, E-mail: xue@ion.chem.utk.edu [Department of Chemistry, University of Tennessee, Knoxville, TN 37996-1600 (United States)

2009-06-08

An electrochemical technique has been developed for ultra-trace (ng L{sup -1}) vanadium (V) measurement. Catalytic adsorptive stripping voltammetry for V analysis was developed at mercury-coated gold micro-wire electrodes (MWEs, 100 {mu}m) in the presence of gallic acid (GA) and bromate ion. A potential of -0.275 V (vs Ag/AgCl) was used to accumulate the complex in acetate buffer (pH 5.0) at the electrode surface followed by a differential pulse voltammetric scan. Parameters affecting the electrochemical response, including pH, concentration of GA and bromate, deposition potential and time have been optimized. Linear response was obtained in the 0-1000 ng L{sup -1} range (2 min deposition), with a detection limit of 0.88 ng L{sup -1}. The method was validated by comparison of results for an unknown solution of V by atomic absorption measurement. The protocol was evaluated in a real sample by measuring the amount of V in river water samples. Thick bismuth film electrodes with protective polystyrene films have also been made and evaluated as a mercury free alternative. However, ng L{sup -1} level detection was only attainable with extended (10 min) deposition times. The proposed use of MWEs for the detection of V is sensitive enough for future use to test V concentration in biological fluids treated by the advanced oxidation process (AOP).

Direct observation of solid-phase adsorbate concentration profile in powdered activated carbon particle to elucidate mechanism of high adsorption capacity on super-powdered activated carbon.

Science.gov (United States)

Ando, Naoya; Matsui, Yoshihiko; Matsushita, Taku; Ohno, Koichi

2011-01-01

Decreasing the particle size of powdered activated carbon (PAC) by pulverization increases its adsorption capacities for natural organic matter (NOM) and polystyrene sulfonate (PSS, which is used as a model adsorbate). A shell adsorption mechanism in which NOM and PSS molecules do not completely penetrate the adsorbent particle and instead preferentially adsorb near the outer surface of the particle has been proposed as an explanation for this adsorption capacity increase. In this report, we present direct evidence to support the shell adsorption mechanism. PAC particles containing adsorbed PSS were sectioned with a focused ion beam, and the solid-phase PSS concentration profiles of the particle cross-sections were directly observed by means of field emission-scanning electron microscopy/energy-dispersive X-ray spectrometry (FE-SEM/EDXS). X-ray emission from sulfur, an index of PSS concentration, was higher in the shell region than in the inner region of the particles. The X-ray emission profile observed by EDXS did not agree completely with the solid-phase PSS concentration profile predicted by shell adsorption model analysis of the PSS isotherm data, but the observed and predicted profiles were not inconsistent when the analytical errors were considered. These EDXS results provide the first direct evidence that PSS is adsorbed mainly in the vicinity of the external surface of the PAC particles, and thus the results support the proposition that the increase in NOM and PSS adsorption capacity with decreasing particle size is due to the increase in external surface area on which the molecules can be adsorbed. Copyright © 2010 Elsevier Ltd. All rights reserved.

Removal of heavy metals from water by zeolite mineral chemically modified. Mercury as a particular case

International Nuclear Information System (INIS)

Gebremedhin H, T.

2002-01-01

Research works on the removal of mercury from water by zeolite minerals show that a small quantity of this element is sorbed. In this work the mercury sorption from aqueous solutions in the presence and absence of Cu(l l), Ni(l l) and/or Zn(l l) by a Mexican zeolite mineral, natural and modified by cisteaminium chloride or cistaminium dichloride, was investigated in acidic p H. The zeolite minerals were characterized by X- Ray diffraction Ftir, scanning electron microscopy and semiquantitative elemental analysis (EDS), surface area analysis (BET) and thermogravimetric analysis (TGA). Mercury from aqueous solutions was quantified by Atomic absorption spectroscopy. The amount of sulphur on the zeolite samples treated with Na CI and modified with cisteaminium chloride (0.375 mmol/g) or cistaminium dichloride(0.475 mmol/g) was found to be higher than that of the zeolite minerals modified with cisteaminium chloride and cistaminium dichloride without treating them with Na CI. The amount of sulphur on the zeolite minerals modified with thiourea was the lowest. The diffusion coefficients and sorption isotherms for mercury were determined in the natural, treated with Na CI and, treated with Na CI and then modified with the cisteaminium chloride or cistaminium dichloride zeolite samples. The retention of mercury was the highest for the zeolite minerals treated Na CI and then modified with cisteaminium chloride or cistaminium dichloride, with adsorption capacity of 0.0511 and 0.0525 mmol Hg/g, respectively. In this research work, it was found that the retention of mercury by the modified minerals was not affected by the presence of Cu (Il), Zn(l l) y Ni (I l) under the experimental conditions. (Author)

Influence of coal properties on mercury uptake from aqueous solution

Energy Technology Data Exchange (ETDEWEB)

Lakatos, J.; Brown, S.D.; Snape, C.E. [Miskolc University, Miskolc-Egyetemvaros (Hungary). Research Inst. of Applied Chemistry

1999-10-01

The uptake of mercury (II) from aqueous solution by a range of coals has been studied and the results have been compared to those for a number of other sorbents, including commercial active carbons and cation-exchange resins. At pH 5 in a buffer medium, the capacities for mercury removal of the low-rank coals and the oxidized bituminous coals investigated are comparable to those of the other sorbents tested. For the lignites investigated, a high content of organic sulfur does not markedly affect the capacity for mercury uptake in relatively neutral and low chloride media, owing to redox reactions being the most likely mechanism involved. However, in highly acidic solutions, the capacities for mercury uptake are considerably greater for the high-sulfur coals investigated than for their low-sulfur counterparts due to chelation being the major sorption process involved. 36 refs., 4 figs., 7 tabs.

Effect of immobilized amine density on cadmium(II) adsorption capacities for ethanediamine-modified magnetic poly-(glycidyl methacrylate) microspheres

Energy Technology Data Exchange (ETDEWEB)

Dong, Tingting [Key Laboratory of Green Process and Engineering, State Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Yang, Liangrong, E-mail: lryang@ipe.ac.cn [Key Laboratory of Green Process and Engineering, State Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190 (China); Pan, Feng; Xing, Huifang; Wang, Li; Yu, Jiemiao [Key Laboratory of Green Process and Engineering, State Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190 (China); Qu, Hongnan [Key Laboratory of Green Process and Engineering, State Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101 (China); Rong, Meng [Key Laboratory of Green Process and Engineering, State Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Liu, Huizhou, E-mail: hzliu@ipe.ac.cn [Key Laboratory of Green Process and Engineering, State Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190 (China)

2017-04-01

A series of ethanediamine (EDA) – modified magnetic poly-(glycidyl methacrylate) (m-PGMA-EDA)microspheres with different amine density were synthesized and their cadmium saturation adsorption capacities were examined. The results showed that the cadmium saturation adsorption capacity increased with the immobilized amine density. However, they did not show strong positive linear correlation in the whole range of amine density examined. The molar ratio of amine groups to the adsorbed cadmium decreased with the increase of amine density and eventually reached a minimum value about 4. It suggested that low immobilized amine density led to low coordination efficiency of the amine. It is hypothesized that the immobilized amine groups needed to be physically close enough to form stable amine-metal complex. When the amine density reached to a critical value 1.25 m mol m{sup −2}, stable amine-cadmium complex (4:1 N/Cd) was proposed to form. To illustrate the coordination mechanism (structure and number) of amine and Cd, FT-IR spectra of m-PGMA-EDA and m-PGMA-EDA-Cd , and X-ray photoelectron spectroscopy (XPS) of PGMA–EDA and PGMA-EDA-Cd were examined and analyzed. - Highlights: • A series of magnetic poly-(glycidyl methacrylate) (m-PGMA-EDA)microspheres with different amine density were synthesized and their cadmium saturation adsorption capacities were examined. • The molar ratio of amine groups to adsorbed cadmium decreased with the increase of amine density and eventually reached a minimum value about 4. • when the amine density reached high enough, 4:1 N/Cd complex was proposed to form, and the hydroxyl also participated in the chelating with Cd.

Preparation of porous diatomite-templated carbons with large adsorption capacity and mesoporous zeolite K-H as a byproduct.

Science.gov (United States)

Liu, Dong; Yuan, Weiwei; Deng, Liangliang; Yu, Wenbin; Sun, Hongjuan; Yuan, Peng

2014-06-15

In this study, KOH activation was performed to enhance the porosity of the diatomite-templated carbon and to increase its adsorption capacity of methylene blue (MB). In addition to serving as the activation agent, KOH was also used as the etchant to remove the diatomite templates. Zeolite K-H was synthesized as a byproduct via utilization of the resultant silicon- and potassium-containing solutions created from the KOH etching of the diatomite templates. The obtained diatomite-based carbons were composed of macroporous carbon pillars and tubes, which were derived from the replication of the diatomite templates and were well preserved after KOH activation. The abundant micropores in the walls of the carbon pillars and tubes were derived from the break and reconfiguration of carbon films during both the removal of the diatomite templates and KOH activation. Compared with the original diatomite-templated carbons and CO2-activated carbons, the KOH-activated carbons had much higher specific surface areas (988 m(2)/g) and pore volumes (0.675 cm(3)/g). Moreover, the KOH-activated carbons possessed larger MB adsorption capacity (the maximum Langmuir adsorption capacity: 645.2 mg/g) than those of the original carbons and CO2-activated carbons. These results showed that KOH activation was a high effective activation method. The zeolite K-H byproduct was obtained by utilizing the silicon- and potassium-containing solution as the silicon and potassium sources. The zeolite exhibited a stick-like morphology and possessed nanosized particles with a mesopore-predominant porous structure which was observed by TEM for the first time. Copyright © 2014 Elsevier Inc. All rights reserved.

Behaviour and quantification studies of terbacil and lenacil in environmental samples using cyclic and adsorptive stripping voltammetry at hanging mercury drop electrode.

Science.gov (United States)

Thriveni, T; Rajesh Kumar, J; Sujatha, D; Sreedhar, N Y

2007-05-01

The cyclic voltammograms of terbacil and lenacil at the hanging mercury drop electrode showed a single well defined four electron irreversible peak in universal buffer of pH 4.0 for both compounds. The peak potentials were shifted to more negative values on the increase of pH of the medium, implying the involvement of protons in the electrode reaction and that the proton transfer reaction precedes the proper electrode process. The four electron single peak may be attributed to the simultaneous reduction of carbonyl groups present in 2 and 4 in pyrimidine ring of terbacil and lenacil to the corresponding hydroxy derivative. Based on the interfacial adsorptive character of the terbacil and lenacil onto the mercury electrode surface, a simple sensitive and low cost differential pulse adsorptive stripping voltammetric procedure was optimized for the analysis of terbacil and lenacil. The optimal operational conditions of the proposed procedure were accumulation potential E (acc) = -0.4 V, accumulation time t (acc) = 80 s, scan rate = 40 mV s(-1), pulse amplitude = 25 mV using a universal buffer pH 4.0 as a supporting electrolyte. The linear concentration range was found to be 1.5 x 10(-5) to 1.2 x 10(-9) mol/l and 1.5 x 10(-5) to 2.5 x 10(-8) mol/l with the lower detection limit of 1.22 x 10(-9) and 2.0 x 10(-8) mol/l. The correlation coefficient and relative standard deviation values are found to be 0.942, 0.996, 1.64% and 1.23%, respectively, for 10 replicants. The procedure was successfully applied for determination of terbacil and lenacil in formulations, mixed formulations, environmental samples such as fruit samples and spiked water samples.

Removal and recovery of gas-phase element mercury by metal oxide-loaded activated carbon

Energy Technology Data Exchange (ETDEWEB)

Mei Zhijian [School of Environmental Science and Engineering, Shanghai Jiao Tong University, 800 Dong Chuan Road, Shanghai 200240 (China); Shen Zhemin [School of Environmental Science and Engineering, Shanghai Jiao Tong University, 800 Dong Chuan Road, Shanghai 200240 (China)], E-mail: pnyql520@hotmail.com; Zhao Qingjie [Shanghai Academy of Environmental Science, 508 Qin-Zhou Road, Shanghai 200233 (China); Wang Wenhua; Zhang Yejian [School of Environmental Science and Engineering, Shanghai Jiao Tong University, 800 Dong Chuan Road, Shanghai 200240 (China)

2008-04-01

The reusability of Co{sub 3}O{sub 4} (AC-Co), MnO{sub 2} (AC-Mn) and CuCoO{sub 4} (AC-CC) loaded activated carbon (AC) and their element mercury removal efficiency had been studied using a laboratory-scale fixed-bed reactor under simulated flue gas conditions. Tests showed that spent AC-Co could be regenerated through heating at 673 K under N{sub 2} atmosphere and the enrichment regenerated Hg{sup 0} could be collected to eliminate the secondary pollution. Regenerated AC-Mn and AC-CC's Hg{sup 0} removal efficiency decreased greatly due to AC's decomposition and MnO{sub 2}'s crystal structure variation. Compared with AC and metal oxides, metal oxide-loaded AC had higher Hg{sup 0} capture ability and capacity due to AC huge surface areas and lots of function groups. TGA analysis results showed that AC-Co and AC-Mn's HgO adsorptive capacity at 523 K reached 19.8 mg g{sup -1} and 5.21 mg g{sup -1}, respectively. High loading values and adsorption temperatures were beneficial to AC-Co's Hg{sup 0} removal efficiency. However, CuCoO{sub 4} and MnO{sub 2}'s AC decomposition ability had negative effect on AC-CC and AC-Mn's performance, respectively, especially at high adsorption temperatures and loading values. SO{sub 2} tests showed that AC-CC had higher anti SO{sub 2}-poisoning ability than AC-Co and AC-Mn.

Analysis of gas-phase mercury sorption with coke and lignite dust

Directory of Open Access Journals (Sweden)

Marczak Marta

2017-01-01

Full Text Available In recent years the problem of mercury emission became a widely discussed topic. Its high impact is caused by its toxicity and ability to accumulate in living organisms, properties that justified the United States Environmental Protection Agency (US EPA to classify mercury as hazardous pollutant. The problem of mercury emission is crucial for countries like Poland, where the most of the emission is caused by coaldepended energy sector. Current technology of mercury removal utilizes adsorption of mercury on the surface of activated carbon. Due to high price of activated carbon, this technological approach seems to be uneconomical and calls for cheaper alternative. One possible solution can be usage of other sorptive materials obtained from thermal processes like coke production. Example of such material is coke dust obtained from dry quenching of coke. The aim of this work was to analyse the sorption potential of lignite and coke dust and determine parameters influencing mercury behaviour during combustion.

Biosorption of mercury from aqueous solutions using highly characterised peats

Directory of Open Access Journals (Sweden)

A.M. Rizzuti

2015-02-01

Full Text Available This research investigated the biosorption of mercury from aqueous solutions by six highly characterised peats. Samples of the peats were tested both in unaltered condition and after being treated with hydrochloric acid (HCl to free up any occupied exchange sites. Other variables tested were sample dose, contact time, mixing temperature, and the concentration and pH of the mercury solution. Desorption studies were also performed, and tests were done to determine whether the peats could be re-used for mercury biosorption. The results indicate that all six peat types biosorb mercury from aqueous solutions extremely well (92−100 % removal and that their mercury removal capacities are not significantly affected by manipulation of the various factors tested. The factor that had the greatest impact on the mercury removal capacities of the peats was the pH of the mercury solution. The optimal mercury solution pH for mercury removal was in the range 5−7 for four of the peats and in the range 2−3 for the other two. The desorption results indicate that it may be possible to recover up to 41 % of the removed mercury. All of the peat types tested can be repeatedly re-used for additional mercury biosorption cycles. Hence, their disposal should not become a hazardous waste problem.

Potassium adsorption behaviour of three Malaysian rice soils

International Nuclear Information System (INIS)

Choudhury, A.T.M.A.; Khanif, Y.M.

2003-01-01

Potassium (K) deficiency exists in different rice growing areas of Malaysia. A study on K adsorption was carried out in three Malaysian rice soils (Guar, Hutan and Kangar series) using six levels of K (0.00,28.77, 33.57, 38.37, 43.16 and 47.96 mmol kg/sup -1/). The data on K adsorption were fitted into Langmuir, Freundlich, and Temkin adsorption equations. Adsorption data were also correlated with pH, cation exchange capacity and organic matter content of the soils. Potassium adsorption increased linearly with increasing level of added K in all the three soils. The rate of increase was the highest in Guar series followed by Kangar and Hutan series, respectively. Potassium adsorption in two soils (Hutan and Kangar) fitted into Langmuir equation while he adsorption data in Guar series did not fit into this equation. Adsorption data in none of the soils fitted well in Freundlich and Temkin adsorption equations. Correlation between K adsorption and pH was significant (r = 0.881,), whereas, correlation of K adsorption with either organic matter content or cation exchange capacity was non-significant. The results of this study indicated that K adsorption is mainly dependent on soil pH. In soils with higher adsorption capacity, more K fertilizer may be needed to get immediate crop response. (author)

Novel sandwich structure adsorptive membranes for removal of 4-nitrotoluene from water

Energy Technology Data Exchange (ETDEWEB)

Guo, Yuexin [College of Chemistry, Beijing Normal University, Beijing 100875 (China); School of Pharmacy, North China University of Science and Technology, Tangshan 063000 (China); Jia, Zhiqian, E-mail: zhqjia@bnu.edu.cn [College of Chemistry, Beijing Normal University, Beijing 100875 (China)

2016-11-05

Highlights: • Novel sandwich PES-SPES/PS-PDVB/PTFE adsorptive membranes were prepared. • The removal efficiency for 4-nitrotoluene is greater than 95% after five recycles. • The membrane showed higher adsorption capacity than that of mixed matrix membrane. - Abstract: Novel sandwich PES-SPES/PS-PDVB/PTFE adsorptive membranes were prepared by a filtration/immersion precipitation method and employed for the removal of 4-nitrotoluene from water. The static adsorption thermodynamics, kinetics, dynamic adsorption/desorption and membrane reusability were investigated. The results showed that the Freundlich model describes the adsorption isotherm satisfactorily. With increased PS-PDVB content, the maximum static adsorption capacity, partition coefficient, apparent adsorption rate constant, and dynamic adsorption capacity all significantly increased. The sandwich membranes showed much higher removal efficiency and adsorption capacity than those of mixed matrix membranes. With respect to dynamics adsorption/desorption, the sandwich membranes exhibited excellent reusability, with a removal efficiency greater than 95% even after five recycles.

Aerobic Mercury-resistant bacteria alter Mercury speciation and retention in the Tagus Estuary (Portugal).

Science.gov (United States)

Figueiredo, Neusa L; Canário, João; O'Driscoll, Nelson J; Duarte, Aida; Carvalho, Cristina

2016-02-01

Aerobic mercury-resistant bacteria were isolated from the sediments of two highly mercury-polluted areas of the Tagus Estuary (Barreiro and Cala do Norte) and one natural reserve area (Alcochete) in order to test their capacity to transform mercury. Bacterial species were identified using 16S rRNA amplification and sequencing techniques and the results indicate the prevalence of Bacillus sp. Resistance patterns to mercurial compounds were established by the determination of minimal inhibitory concentrations. Representative Hg-resistant bacteria were further tested for transformation pathways (reduction, volatilization and methylation) in cultures containing mercury chloride. Bacterial Hg-methylation was carried out by Vibrio fluvialis, Bacillus megaterium and Serratia marcescens that transformed 2-8% of total mercury into methylmercury in 48h. In addition, most of the HgR bacterial isolates showed Hg(2+)-reduction andHg(0)-volatilization resulting 6-50% mercury loss from the culture media. In summary, the results obtained under controlled laboratory conditions indicate that aerobic Hg-resistant bacteria from the Tagus Estuary significantly affect both the methylation and reduction of mercury and may have a dual face by providing a pathway for pollution dispersion while forming methylmercury, which is highly toxic for living organisms. Copyright © 2015 Elsevier Inc. All rights reserved.

Adsorption of lysozyme unto silica and polystyrene surfaces in ...

African Journals Online (AJOL)

The adsorption capacity of lysozyme (chicken egg white) from aqueous solutions unto silica and polystyrene interfaces was studied at varying lysozyme concentrations and ionic strength. The studies revealed an increase in adsorption capacity with increase in concentration and with maximum adsorption densities of 1.34 ...

Adsorption of antibiotics on microplastics.

Science.gov (United States)

Li, Jia; Zhang, Kaina; Zhang, Hua

2018-06-01

Microplastics and antibiotics are two classes of emerging contaminants with proposed negative impacts to aqueous ecosystems. Adsorption of antibiotics on microplastics may result in their long-range transport and may cause compound combination effects. In this study, we investigated the adsorption of 5 antibiotics [sulfadiazine (SDZ), amoxicillin (AMX), tetracycline (TC), ciprofloxacin (CIP), and trimethoprim (TMP)] on 5 types of microplastics [polyethylene (PE), polystyrene (PS), polypropylene (PP), polyamide (PA), and polyvinyl chloride (PVC)] in the freshwater and seawater systems. Scanning Electron Microscope (SEM) and X-ray diffractometer (XRD) analysis revealed that microplastics have different surface characterizes and various degrees of crystalline. Adsorption isotherms demonstrated that PA had the strongest adsorption capacity for antibiotics with distribution coefficient (K d ) values ranged from 7.36 ± 0.257 to 756 ± 48.0 L kg -1 in the freshwater system, which can be attributed to its porous structure and hydrogen bonding. Relatively low adsorption capacity was observed on other four microplastics. The adsorption amounts of 5 antibiotics on PS, PE, PP, and PVC decreased in the order of CIP > AMX > TMP > SDZ > TC with K f correlated positively with octanol-water partition coefficients (Log K ow ). Comparing to freshwater system, adsorption capacity in seawater decreased significantly and no adsorption was observed for CIP and AMX. Our results indicated that commonly observed polyamide particles can serve as a carrier of antibiotics in the aquatic environment. Copyright © 2018 Elsevier Ltd. All rights reserved.

Sonochemical surface functionalization of exfoliated LDH: Effect on textural properties, CO2 adsorption, cyclic regeneration capacities and subsequent gas uptake for simultaneous methanol synthesis.

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Ezeh, Collins I; Huang, Xiani; Yang, Xiaogang; Sun, Cheng-Gong; Wang, Jiawei

2017-11-01

To improve CO 2 adsorption, amine modified Layered double hydroxide (LDH) were prepared via a two stage process, SDS/APTS intercalation was supported by ultrasonic irradiation and then followed by MEA extraction. The prepared samples were characterised using Scanning electron microscope-Energy dispersive X-ray spectroscopy (SEM-EDX), X-ray Photoelectron Spectroscopy (XPS), X-ray diffraction (XRD), Temperature Programmed Desorption (TPD), Brunauer-Emmett-Teller (BET), and Thermogravimetric analysis (TGA), respectively. The characterisation results were compared with those obtained using the conventional preparation method with consideration to the effect of sonochemical functionalization on textural properties, adsorption capacity, regeneration and lifetime of the LDH adsorbent. It is found that LDHs prepared by sonochemical modification had improved pore structure and CO 2 adsorption capacity, depending on sonic intensity. This is attributed to the enhanced deprotonation of activated amino functional groups via the sonochemical process. Subsequently, this improved the amine loading and effective amine efficiency by 60% of the conventional. In addition, the sonochemical process improved the thermal stability of the adsorbent and also, reduced the irreversible CO 2 uptake, CUirrev, from 0.18mmol/g to 0.03mmol/g. Subsequently, improving the lifetime and ease of regenerating the adsorbent respectively. This is authenticated by subjecting the prepared adsorbents to series of thermal swing adsorption (TSA) cycles until its adsorption capacity goes below 60% of the original CO 2 uptake. While the conventional adsorbent underwent a 10 TSA cycles before breaking down, the sonochemically functionalized LDH went further than 30 TSA cycles. Copyright © 2017 Elsevier B.V. All rights reserved.

Simulation of the adsorption capacity of polar organic compounds and dyes from water onto activated carbons: Model development and validation

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Warisa Bunmahotama

2018-03-01

Full Text Available A model approach is developed to simulate the adsorption isotherms of low-molecular-weight polar organic compounds (LMWPOCs, halogenated LMWPOCs, and dye molecules onto activated carbons (AC. The models were based on the Dubinin–Astakhov equation, with the limiting pore volume of adsorbent estimated from the pore size distribution data, and the adsorption affinity of the adsorbate described by the molecular connectivity index. The models were used to simulate the adsorption data of 87 LMWPOCs onto six ACs, 25 halogenated LMWPOCs onto two ACs and 22 dyes onto three ACs. The developed models follow the experimental data fairly well, with errors of 49, 33 and 43% for the tested LMWPOCs, halogenated LMWPOCs, and dyes, respectively. This study shows that the developed model approach may provide a simple means for the estimation of adsorption capacity for LMWPOCs and dyes onto ACs in water.

Synthesis and granulation of a titanosilicate with adsorption capacity for Cs to be used for treating de ILLW of the Ezeiza Radioisotope Production Plant

International Nuclear Information System (INIS)

Curi, Rodrigo; Bianchi, Hugo L; Luca, Vittorio

2012-01-01

The sitinakite structured titanosilicate is widely used for treating ILLW thanks to its capacity for adsorbing both Cs-137 and Sr-90. Its effectiveness lies in its incredibly high selectivity for such radioisotopes, which makes it useful in complex isotope solutions and even in strong acid and alkaline conditions. In Argentina, an off-the-shelve titanosilicate was used in Ezeiza's radioisotope production plant. Because of commercial restrictions, it is no longer available so an inhouse production is being developed. The aim of this project consists of the following: 1. Synthesis of titanosilicate and structural characterization 2. Adsorption kinetics of Cs + 3. Upscale of the synthesis process 4. Assessment of the influence of synthesis temperature and time on product crystallinity 5. Measurement of adsorption capacity of commercial titanosilicates IE910, IE911 and novel RC15H 6. Separative performance column essay and breakthrough plot 7. Chemical and radiolysis resistance of the adsorbent powder binder Polyacrylonitrile (PAN) in contact with the actual waste Throughout this work we have studied the optimum synthesis conditions capable of rendering a sitinakite structured titanosilicate, assessed its Cs + adsorption kinetics, adsorption capacity, crystal phase and purity via DRX, particle size with Laser Light Scattering technique. We have also conducted column breakthrough experiments and tried the chemical and radiolysis resistance of the final product (author)

Vapor mercury uptake with sulphur impregnated active carbons derived using sulphur dioxide

International Nuclear Information System (INIS)

Tong, S.; Methta, H.; Ahmed, I.; Morris, E.; Fuentes de Maria, L.; Jia, C.Q.

2008-01-01

Active carbon adsorption is the primary technology used for removal of vapour mercury from flue gases in coal-fired power plants, municipal solid waste combustors, and other sources. It can be carried out using two different processes, notably injection of powder active carbon into flue gas streams upstream of the particulate collection devices, and filtration with a granular active carbon fixed bed downstream of the flue gas desulphurization units and/or particulate collectors. This paper presented an investigation of vapour mercury uptake performance of laboratory-made sulphur impregnated active carbons (SIACs) using a fixed bed reactor in a temperature range of 25 to 200 degrees Celsius. The materials and methods as well as the properties of activated carbons studied were presented. The experimental set-up was also described. The paper discussed the effects of initial concentration, the flow rate, the loading amount of SIACs, temperature, and the sulphur impregnation on the mercury uptake performance. The study showed that SIACs produced with sulphur dioxide exhibited a more complicated behaviour when temperature was varied, implying a mixed adsorption mechanism. 10 refs., 3 tabs., 8 figs

Enhanced sorption of mercury from compact fluorescent bulbs and contaminated water streams using functionalized multiwalled carbon nanotubes

International Nuclear Information System (INIS)

Gupta, Avinash; Vidyarthi, S.R.; Sankararamakrishnan, Nalini

2014-01-01

Highlights: • Oxidized (CNT-OX), CNT-I, CNT-S were prepared. • Capacity of CNT-S (151.5 mg/g) was higher than other CNTs. • Applied to the removal of Hg(II) from spiked and natural coal wash waters. • Applied to the removal of Hg(0) from compact fluorescent lamps. - Abstract: Three different functionalized multiwalled carbon nanotubes were prepared, namely, oxidized CNTs (CNT-OX), iodide incorporated MWCNT (CNT-I) and sulfur incorporated MWCNT (CNT-S). The as prepared adsorbents were structurally characterized by various spectral techniques like scanning electron microscopy (SEM), energy dispersive X-ray (EDAX), Brunauer, Emmett, and Teller (BET) surface area analyzer, Fourier transform infra red (FTIR) and Raman spectroscopy. Loading of iodide and sulfur was evident from the EDAX graphs. The adsorption properties of Hg 2+ as a function of pH, contact time and initial metal concentration were characterized by Cold vapor AAS. The adsorption kinetics fitted the Pseudo second order kinetics and equilibrium was reached within 90 min. The experimental data were modeled with Langmuir, Freundlich, Dubinin-Redushkevich and Temkin isotherms and various isotherm parameters were evaluated. It was found that the mercury adsorption capacity for the prepared adsorbents were in the order of CNT-S > CNT-I > CNT-OX > CNT. Studies have been conducted to demonstrate the applicability of the sorbent toward the removal of Hg(0) from broken compact fluorescent light (CFL) bulbs and Hg(II) from contaminated water streams

Adsorption characteristics of siloxanes in landfill gas by the adsorption equilibrium test.

Science.gov (United States)

Nam, Sangchul; Namkoong, Wan; Kang, Jeong-Hee; Park, Jin-Kyu; Lee, Namhoon

2013-10-01

Due to the increase in energy cost by constantly high oil prices and the obligation to reduce greenhouse effect gases, landfill gas is frequently used as an alternative energy source for producing heat and electricity. Most of landfill gas utility facilities, however, are experiencing problems controlling siloxanes from landfill gas as their catalytic oxidizers are becoming fouled by silicon dioxide dust. To evaluate adsorption characteristics of siloxanes, an adsorption equilibrium test was conducted and parameters in the Freundlich and Langmuir isotherms were analyzed. Coconut activated carbon (CA1), coal activated carbon (CA2), impregnated activated carbon (CA3), silicagel (NCA1), and activated alumina (NCA2) were used for the adsorption of the mixed siloxane which contained hexamethyldisiloxane (L2), octamethylcyclotetrasiloxane (D4), and decamethylcyclopentasiloxane (D5). L2 had higher removal efficiency in noncarbon adsorbents compared to carbon adsorbents. The application of Langmuir and Freundlich adsorption isotherm demonstrated that coconut based CA1 and CA3 provided higher adsorption capacity on L2. And CA2 and NCA1 provided higher adsorption capacity on D4 and D5. Based on the experimental results, L2, D4, and D5 were converted by adsorption and desorption in noncarbon adsorbents. Adsorption affinity of siloxane is considered to be affect by the pore size distribution of the adsorbents and by the molecular size of each siloxane. Copyright © 2013 Elsevier Ltd. All rights reserved.

Improving the capacity of lithium-sulfur batteries by tailoring the polysulfide adsorption efficiency of hierarchical oxygen/nitrogen-functionalized carbon host materials.

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Schneider, Artur; Janek, Jürgen; Brezesinski, Torsten

2017-03-22

The use of monolithic carbons with structural hierarchy and varying amounts of nitrogen and oxygen functionalities as sulfur host materials in high-loading lithium-sulfur cells is reported. The primary focus is on the strength of the polysulfide/carbon interaction with the goal of assessing the effect of (surface) dopant concentration on cathode performance. The adsorption capacity - which is a measure of the interaction strength between the intermediate lithium polysulfide species and the carbon - was found to scale almost linearly with the nitrogen level. Likewise, the discharge capacity of lithium-sulfur cells increased linearly. This positive correlation can be explained by the favorable effect of nitrogen on both the chemical and electronic properties of the carbon host. The incorporation of additional oxygen-containing surface groups into highly nitrogen-functionalized carbon helped to further enhance the polysulfide adsorption efficiency, and therefore the reversible cell capacity. Overall, the areal capacity could be increased by almost 70% to around 3 mA h cm -2 . We believe that the design parameters described here provide a blueprint for future carbon-based nanocomposites for high-performance lithium-sulfur cells.

Removal of mercury (II), elemental mercury and arsenic from simulated flue gas by ammonium sulphide.

Science.gov (United States)

Ning, Ping; Guo, Xiaolong; Wang, Xueqian; Wang, Ping; Ma, Yixing; Lan, Yi

2015-01-01

A tubular resistance furnace was used as a reactor to simulate mercury and arsenic in smelter flue gases by heating mercury and arsenic compounds. The flue gas containing Hg(2+), Hg(0) and As was treated with ammonium sulphide. The experiment was conducted to investigate the effects of varying the concentration of ammonium sulphide, the pH value of ammonium sulphide, the temperature of ammonium sulphide, the presence of SO2 and the presence of sulphite ion on removal efficiency. The prepared adsorption products were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy and scanning electron microscopy. The results showed that the optimal concentration of ammonium sulphide was 0.8 mol/L. The optimal pH value of ammonium sulphide was 10, and the optimal temperature of ammonium sulphide was 20°C.Under the optimum conditions, the removal efficiency of Hg(2+), Hg(0) and As could reach 99%, 88.8%, 98%, respectively. In addition, SO2 and sulphite ion could reduce the removal efficiency of mercury and arsenic from simulated flue gas.

Theoretical study on the gas adsorption capacity and selectivity of CPM-200-In/Mg and CPM-200-In/Mg-X (-X = -NH2, -OH, -N, -F).

Science.gov (United States)

Liu, Xiao-le; Chen, Guang-Hui; Wang, Xiu-Jun; Li, Peng; Song, Yi-Bing; Li, Rui-Yan

2017-11-15

The adsorption capacities of a heterometallic metal-organic framework (CPM-200-In/Mg) to VOCs (HCHO, C 2 H 4 , CH 4 , C 2 H 2 , C 3 H 8 , C 2 H 6 , C 2 H 3 Cl, C 2 H 2 Cl 2 , CH 2 Cl 2 and CHCl 3 ) and some inorganic gas molecules (HCN, SO 2 , NO, CO 2 , CO, H 2 S and NH 3 ), as well as its selectivity in ternary mixture systems of natural gas and post-combustion flue gas are theoretically explored at the grand canonical Monte Carlo (GCMC) and density functional theory (DFT) levels. It is shown that CPM-200-In/Mg is suitable for the adsorption of VOCs, particularly for HCHO (up to 0.39 g g -1 at 298 K and 1 bar), and the adsorption capacities of some inorganic gas molecules such as SO 2 , H 2 S and CO 2 match well with the sequence of their polarizability (SO 2 > H 2 S > CO 2 ). The large adsorption capacities of HCN and HCHO in the framework result from the strong interaction between adsorbates and metal centers, based on analyzing the radial distribution functions (RDF). Comparing C 2 H 4 and CH 4 molecules interacting with CPM-200-In/Mg by VDW interaction, we speculate that the high adsorption capacities of their chlorine derivatives in the framework could be due to the existence of halogen bonding or strong electrostatic and VDW interactions. It is found that the basic groups, including -NH 2 , -N and -OH, can effectively improve both the adsorption capacities and selectivity of CPM-200-In/Mg for harmful gases. Note that the adsorption capacity of CPM-200-In/Mg-NH 2 (site 2) (245 cm 3 g -1 ) for CO 2 exceeded that of MOF-74-Mg (228 cm 3 g -1 ) at 273 K and 1 bar and that for HCHO can reach 0.41 g g -1 , which is almost twice that of 438-MOF and nearly 45 times of that in active carbon. Moreover, for natural gas mixtures, the decarburization and desulfurization abilities of CPM-200-In/Mg-NH 2 (site 2) have exceeded those of the MOF-74 series, while for post-combustion flue gas mixtures, the desulfurization ability of CPM-200-In/Mg-NH 2 (site 2) is still

Adsorption of Pb(II by Activated Pyrolytic Char from Used Tire

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Lu Ping

2016-01-01

Full Text Available As a renewable resource, the pyrolytic char derived from used tire has promising adsorption capacities owing to its similar structure and properties with active carbon. The purification and activation of the pyrolytic char from used tire, as well as the application of this material in the adsorption of Pb(II in water is conducted. The influences on the adsorption capacity by temperature and pH value are investigated and discussed; the adsorption thermodynamics and kinetics are also studied. The results show that the pyrolytic char from used tire has remarkable adsorption capacity for Pb(II, and the adsorption is an endothermic process complying with the Langmuir isotherm. The adsorption kinetics is a pseudo second-order reaction.

Adsorption of dyes onto activated carbon cloth: using QSPRs as tools to approach adsorption mechanisms.

Science.gov (United States)

Metivier-Pignon, Hélène; Faur, Catherine; Le Cloirec, Pierre

2007-01-01

The present study aimed to investigate the adsorption of dyes onto activated carbon cloths. Kinetics and isotherms were studied based on results of batch reactors to constitute databases for the adsorption rates and capacities of 22 commercial dyes. Added to a qualitative analysis of experimental results, quantitative structure property relationships (QSPRs) were used to determine the structural features that influence most adsorption processes. QSPRs consisted of multiple linear regressions correlating adsorption parameters with molecular connectivity indices (MCIs) as molecular descriptors. Results related to adsorption kinetics showed that the size of molecules was the significant feature, the high order MCIs involved in QSPRs indicating the influence of a critical size on adsorption rate. Improved statistical fits were obtained when the database was divided according to the chemical classes of dyes. As regards to adsorption isotherms, their particular form led to the use of saturation capacity as the adsorption parameter. By contrast with adsorption kinetics, molecular overcrowding seemed to be of less influence on adsorption equilibrium. In this case, MCIs included in the QSPR were more related to details of the molecular structure. The robustness of the QSPR assessed for azo dyes was studied for the other dyes. Although the small size of the database limited predictive ability, features relevant to the influence of the database composition on QSPRs have been highlighted.

Sorbents for the oxidation and removal of mercury

Science.gov (United States)

Olson, Edwin S [Grand Forks, ND; Holmes, Michael J [Thompson, ND; Pavlish, John H [East Grand Forks, MN

2008-10-14

A promoted activated carbon sorbent is described that is highly effective for the removal of mercury from flue gas streams. The sorbent comprises a new modified carbon form containing reactive forms of halogen and halides. Optional components may be added to increase reactivity and mercury capacity. These may be added directly with the sorbent, or to the flue gas to enhance sorbent performance and/or mercury capture. Mercury removal efficiencies obtained exceed conventional methods. The sorbent can be regenerated and reused. Sorbent treatment and preparation methods are also described. New methods for in-flight preparation, introduction, and control of the active sorbent into the mercury contaminated gas stream are described.

Sorbents for the oxidation and removal of mercury

Science.gov (United States)

Olson, Edwin S [Grand Forks, ND; Holmes, Michael J [Thompson, ND; Pavlish, John H [East Grand Forks, MN

2012-05-01

A promoted activated carbon sorbent is described that is highly effective for the removal of mercury from flue gas streams. The sorbent comprises a new modified carbon form containing reactive forms of halogen and halides. Optional components may be added to increase reactivity and mercury capacity. These may be added directly with the sorbent, or to the flue gas to enhance sorbent performance and/or mercury capture. Mercury removal efficiencies obtained exceed conventional methods. The sorbent can be regenerated and reused. Sorbent treatment and preparation methods are also described. New methods for in-flight preparation, introduction, and control of the active sorbent into the mercury contaminated gas stream are described.

Contribution of Ash Content Related to Methane Adsorption Behaviors of Bituminous Coals

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Yanyan Feng

2014-01-01

Full Text Available Methane adsorption isotherms on coals with varying ash contents were investigated. The textural properties were characterized by N2 adsorption/desorption isotherm at 77 K, and methane adsorption characteristics were measured at pressures up to 4.0 MPa at 298 K, 313 K, and 328 K, respectively. The Dubinin-Astakhov model and the Polanyi potential theory were employed to fit the experimental data. As a result, ash content correlated strongly to methane adsorption capacity. Over the ash range studied, 9.35% to 21.24%, the average increase in methane adsorption capacity was 0.021 mmol/g for each 1.0% rise in ash content. With the increasing ash content range of 21.24%~43.47%, a reduction in the maximum adsorption capacities of coals was observed. In addition, there was a positive correlation between the saturated adsorption capacity and the specific surface area and micropore volume of samples. Further, this study presented the heat of adsorption, the isosteric heat of adsorption, and the adsorbed phase specific heat capacity for methane adsorption on various coals. Employing the proposed thermodynamic approaches, the thermodynamic maps of the adsorption processes of coalbed methane were conducive to the understanding of the coal and gas simultaneous extraction.

Synthesis of polycationic bentonite-ionene complexes and their benzene adsorption capacity

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Valquíria Campos

2015-04-01

Full Text Available The purpose of this work was to structurally modify clays in order to incorporate water-insoluble molecules, such as petroleum hydrocarbons. The potential for ion exchange of quaternary ammonium salts was studied, which revealed their ability to interact with anions on the cationic surface, for environmental applications of the material. Ionenes, also known as polycations, have many potential uses in environmental applications. In this work, cationic aliphatic ammonium polyionenes, specifically 3,6-ionene and 3,6-dodecylionene, were prepared for incorporation into clay to form bentonite-ionene complexes. The intercalation of bentonite with ionene polymers resulted in an increase in the basal spacing of 3,6-dodecylionene from 1.5-3.5 nm. The higher d001 spacing of 3,6-dodecylionene samples than that of 3,6-ionene samples may be attributed to their longer tail length. The behavior of the TG/DTG curves and the activation energy values suggest that 3,6-dodecylionene (E = 174.85 kJ mol–1 is thermally more stable than 3,6 ionene (E = 115.52 kJ mol–1 complexes. The adsorption of benzene by 3,6-ionene and 3,6-dodecylionene was also investigated. The increase in benzene concentrations resulted in increased benzene adsorption by the sorbents tested in this work. The sorption capacity of benzene on ionene-modified bentonite was in the order of 3,6-dodecylionene > 3,6-ionene.

A Novel Absorbent of Nano-Fe Loaded Biomass Char and Its Enhanced Adsorption Capacity for Phosphate in Water

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Hongguang Zhou

2013-01-01

Full Text Available A novel composite adsorbent of Fe loaded biomass char (Fe-BC was fabricated to treat phosphorus in water. Fe-BC was prepared by a procedure including metal complex anion incorporation and precipitation with the pyrolysis char of corn straw as supporting material. The abundant porous structures of the as-prepared sample can be easily observed from its scanning electron microscopy (SEM images. Observations by X-ray diffraction (XRD and X-ray photoelectron spectroscopy (XPS analyses show that inorganic nanoiron oxides deposited in the composite could be amorphous hydrous iron oxide α-FeOOH. Adsorption of phosphate onto the Fe-BC composite and its precursor (BC from aqueous solutions were investigated and discussed. The equilibrium adsorption data of phosphate was described by Langmuir and Freundlich models, and Langmuir isotherm was found to be better fitted than Freundlich isotherm. The maximum phosphate adsorption capacity for phosphate of Fe-BC was as high as 35.43 mg/g, approximately 2.3 times of BC at 25°C. The adsorption kinetics data were better fitted by pseudo-second-order model and intraparticle diffusion model, indicating that the adsorption process was complex. The Fe-BC composite has been proved as an effective adsorbent of phosphate from aqueous solutions owing to its unique porous structures and the greater Lewis basicity of the α-FeOOH.

Equilibrium, kinetic and thermodynamic studies on the adsorption of phenol onto graphene

Energy Technology Data Exchange (ETDEWEB)

Li, Yanhui, E-mail: liyanhui@tsinghua.org.cn [Laboratory of Fiber Materials and Modern Textile, The Growing Base for State Key Laboratory, College of Electromechanical Engineering, Qingdao University, 308 Ningxia Road, Qingdao 266071 (China); Du, Qiuju; Liu, Tonghao; Sun, Jiankun; Jiao, Yuqin [Laboratory of Fiber Materials and Modern Textile, The Growing Base for State Key Laboratory, College of Electromechanical Engineering, Qingdao University, 308 Ningxia Road, Qingdao 266071 (China); Xia, Yanzhi, E-mail: xiayzh@qdu.edu.cn [Laboratory of Fiber Materials and Modern Textile, The Growing Base for State Key Laboratory, College of Electromechanical Engineering, Qingdao University, 308 Ningxia Road, Qingdao 266071 (China); Xia, Linhua; Wang, Zonghua [Laboratory of Fiber Materials and Modern Textile, The Growing Base for State Key Laboratory, College of Electromechanical Engineering, Qingdao University, 308 Ningxia Road, Qingdao 266071 (China); Zhang, Wei; Wang, Kunlin; Zhu, Hongwei; Wu, Dehai [Key Laboratory for Advanced Manufacturing by Material Processing Technology, Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China)

2012-08-15

Graphical abstract: The effect of temperature on phenol adsorbed by graphene shows that the equilibrium adsorption capacity of phenol increases with the increase in temperature from 285 to 333 K. Increasing adsorption capacities with temperature indicates that the adsorption of phenol is controlled by an endothermic reaction. Highlights: ► The graphene has high phenol adsorption capacity. ► The graphene has a high specific surface area of 305 m{sup 2}/g. ► The adsorption capacity is high at acidic pH range. ► The graphene has rapid phenol adsorption rate. ► Phenol adsorption is a spontaneous and endothermic process. -- Abstract: Graphene, a new member of carbon family, has been prepared, characterized and used as adsorbent to remove phenol from aqueous solution. The effect parameters including pH, dosage, contact time, and temperature on the adsorption properties of phenol onto graphene were investigated. The results showed that the maximum adsorption capacity can reach 28.26 mg/g at the conditions of initial phenol concentration of 50 mg/L, pH 6.3 and 285 K. Adsorption data were well described by both Freundlich and Langmuir models. The kinetic study illustrated that the adsorption of phenol onto graphene fit the pseudo second-order model. The thermodynamic parameters indicated that the adsorption of phenol onto graphene was endothermic and spontaneous.

Equilibrium, kinetic and thermodynamic studies on the adsorption of phenol onto graphene

International Nuclear Information System (INIS)

Li, Yanhui; Du, Qiuju; Liu, Tonghao; Sun, Jiankun; Jiao, Yuqin; Xia, Yanzhi; Xia, Linhua; Wang, Zonghua; Zhang, Wei; Wang, Kunlin; Zhu, Hongwei; Wu, Dehai

2012-01-01

Graphical abstract: The effect of temperature on phenol adsorbed by graphene shows that the equilibrium adsorption capacity of phenol increases with the increase in temperature from 285 to 333 K. Increasing adsorption capacities with temperature indicates that the adsorption of phenol is controlled by an endothermic reaction. Highlights: ► The graphene has high phenol adsorption capacity. ► The graphene has a high specific surface area of 305 m 2 /g. ► The adsorption capacity is high at acidic pH range. ► The graphene has rapid phenol adsorption rate. ► Phenol adsorption is a spontaneous and endothermic process. -- Abstract: Graphene, a new member of carbon family, has been prepared, characterized and used as adsorbent to remove phenol from aqueous solution. The effect parameters including pH, dosage, contact time, and temperature on the adsorption properties of phenol onto graphene were investigated. The results showed that the maximum adsorption capacity can reach 28.26 mg/g at the conditions of initial phenol concentration of 50 mg/L, pH 6.3 and 285 K. Adsorption data were well described by both Freundlich and Langmuir models. The kinetic study illustrated that the adsorption of phenol onto graphene fit the pseudo second-order model. The thermodynamic parameters indicated that the adsorption of phenol onto graphene was endothermic and spontaneous.

Reprocessing and reuse of waste tire rubber to solve air-quality related problems

Science.gov (United States)

Lehmann, C.M.B.; Rostam-Abadi, M.; Rood, M.J.; Sun, Jielun

1998-01-01

There is a potential for using waste tire rubber to make activated-carbon adsorbents for air-quality control applications. Such an approach provides a recycling path for waste tires and the production of new adsorbents from a low-cost waste material. Tire-derived activated carbons (TDACs) were prepared from waste tires. The resulting products are generally mesoporous, with N2-BET specific surface areas ranging from 239 to 1031 m2/g. TDACs were tested for their ability to store natural gas and remove organic compounds and mercury species from gas streams. TDACs are able to achieve 36% of the recommended adsorbed natural gas (methane) storage capacity for natural-gas-fueled vehicles. Equilibrium adsorption capacities for CH4 achieved by TDACs are comparable to Calgon BPL, a commercially available activated-carbon adsorbent. The acetone adsorption capacity for a TDAC is 67% of the adsorption capacity achieved by BPL at 1 vol % acetone. Adsorption capacities of mercury in simulated flue-gas streams are, in general, larger than adsorption capacities achieved by coal-derived activated carbons (CDACs) and BPL. Although TDACs may not perform as well as commercial adsorbents in some air pollution control applications, the potential lower cost of TDACS should be considered when evaluating economics.

[Adsorption of heavy metals on the surface of birnessite relationship with its Mn average oxidation state and adsorption sites].

Science.gov (United States)

Wang, Yan; Tan, Wen-Feng; Feng, Xiong-Han; Qiu, Guo-Hong; Liu, Fan

2011-10-01

Adsorption characteristics of mineral surface for heavy metal ions are largely determined by the type and amount of surface adsorption sites. However, the effects of substructure variance in manganese oxide on the adsorption sites and adsorption characteristics remain unclear. Adsorption experiments and powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) were combined to examine the adsorption characteristics of Pb2+, Cu2+, Zn2+ and Cd2+ sequestration by birnessites with different Mn average oxidation state (AOS), and the Mn AOS dependent adsorption sites and adsorption characteristics. The results show that the maximum adsorption capacity of Pb2+, Cu2+, Zn2+ and Cd2+ increased with increasing birnessite Mn AOS. The adsorption capacity followed the order of Pb2+ > Cu2+ > Zn2+ > Cd2+. The observations suggest that there exist two sites on the surface of birnessite, i. e., high-binding-energy site (HBE site) and low-binding-energy site (LBE site). With the increase of Mn AOS for birnessites, the amount of HBE sites for heavy metal ions adsorption remarkably increased. On the other hand, variation in the amount of LBE sites was insignificant. The amount of LBE sites is much more than those of HBE sites on the surface of birnessite with low Mn AOS. Nevertheless, both amounts on the surface of birnessite with high Mn AOS are very close to each other. Therefore, the heavy metal ions adsorption capacity on birnessite is largely determined by the amount of HBE sites. On birnessite surface, adsorption of Cu2+, Zn2+, and Cd2+ mostly occurred at HBE sites. In comparison with Zn2+ and Cd2+, more Cu2+ adsorbed on the LBW sites. Pb2+ adsorption maybe occupy at both LBE sites and HBE sites simultaneously.

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

Energy Technology Data Exchange (ETDEWEB)

Xiaodong, Dai [Chemistry and Chemical Engineering School, China University of Petroleum, Dongying 257061, Shandong (China); Institute for Sustainability and Innovation, Victoria University, Melbourne, VIC 8001 (Australia); Zou, Linda [SA Water Centre for Water Management and Reuse, University of South Australia, Adelaide, SA5095 (Australia); Zifeng, Yan [Chemistry and Chemical Engineering School, China University of Petroleum, Dongying 257061, Shandong (China); Millikan, Mary [Institute for Sustainability and Innovation, Victoria University, Melbourne, VIC 8001 (Australia)

2009-08-30

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

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

International Nuclear Information System (INIS)

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

2009-01-01

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

Multicomponent Adsorption Model for Polar and Associating Mixtures

DEFF Research Database (Denmark)

Nesterov, Igor; Shapiro, Alexander; Kontogeorgis, Georgios M.

2015-01-01

of these problems could be due to the fact that the original MPTA assumes that a given adsorbent has the same adsorption capacity (for example, porous volume) for all the adsorbed substances and is adjusted simultaneously to many data. This is a simplified picture, as experimental data indicate that the adsorption......-Radushkevich-Astakhov potentials and the potentials directly restored from experimental data by solving the inverse problem. Application of the latter potentials Clearly demonstrates the importance of the difference in adsorption capacities. However, the quality of prediction of binary adsorption is similar for both potentials...

Enhancement of methylbenzene adsorption capacity through cetyl trimethyl ammonium bromide-modified activated carbon derived from Astragalus residue

Science.gov (United States)

Feng, Ningchuan; Zhang, Yumei; Fan, Wei; Zhu, Meilin

2018-02-01

Activated carbon was prepared from astragalus residue by KOH and then treated with cetyl trimethyl ammonium bromide (CTAB) and used for the removal of methylbenzene from aqueous solution. The samples were characterized by FTIR, XRD, SEM and Boehm titration. The results showed that CTAB changed the physicochemical properties of activated carbon significantly. The isotherm adsorption studies of methylbenzene onto the astragalus residue activated carbon (ASC) and CTAB-modified astragalus residue activated carbon (ASCCTAB) were examined by using batch techniques and agreed well with the Langmuir model. The maximum adsorption capacity of ASC and ASC-CTAB for methylbenzene determined from the Langmuir model was183.56 mg/g and 235.18 mg/g, respectively. The results indicated that using CTAB as a modifier for ASC modification could markedly enhance the methylbenzene removal from water.

Effect of hydrophobicity of pharmaceuticals and personal care products for adsorption on activated carbon: Adsorption isotherms, kinetics and mechanism.

Science.gov (United States)

Kaur, Harkirat; Bansiwal, Amit; Hippargi, Girivyankatesh; Pophali, Girish R

2017-09-11

Adsorption of three pharmaceuticals and personal care products (PPCPs), namely caffeine, ibuprofen and triclosan on commercial powdered activated carbon was examined in aqueous medium. The contaminants were chosen based on their diverse log K ow (octanol-water partition coefficient) viz. - 0.07 for caffeine, 3.97 for ibuprofen and 4.76 for triclosan to examine the role of hydrophobicity on adsorption process. The adsorbent characterisation was achieved using BET surface area, SEM, pore size distribution studies and FTIR. Influence of mass of PAC, contact time, solution pH and initial concentration on adsorption capacity of PAC was studied. Adsorption isotherms and kinetics were applied to establish the mechanism of adsorption. The kinetics followed pseudo-second order with physisorption occurring through particle diffusion. The Freundlich model fitted best among the isotherm models. The adsorption capacity increased in the order CFN activated carbon.

Volatile organic compounds adsorption using different types of adsorbent

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Pimanmes Chanayotha

2014-09-01

Full Text Available Adsorbents were synthesized from coconut shell, coal and coke by pyrolysis followed by chemical activation process. These synthesized materials were used as adsorbents in adsorption test to determine the amount of volatile organic compounds (VOCs namely, 2-Hydroxyethyl methacrylate (HEMA, Octamethylcyclotetrasiloxane and Alkanes standard solution (C8-C20. The adsorption capacities of both synthesized adsorbents and commercial grade adsorbents (Carbotrap™ B and Carbotrap™ C were also compared. It was found that adsorbent A402, which was produced from coconut shell, activated with 40% (wt. potassium hydroxide and at activating temperature of 800°C for 1 hr, could adsorb higher amount of both HEMA and Octamethylcyclotetrasiloxane than other synthesized adsorbents. The maximum adsorption capacity of adsorbent A402 in adsorbing HEMA and Octamethylcyclotetrasiloxane were 77.87% and 50.82% respectively. These adsorption capabilities were 79.73% and 70.07% of the adsorption capacity of the commercial adsorbent Carbotrap™ B respectively. All three types of the synthesized adsorbent (A402, C302, C402 showed the capability to adsorb alkanes standard solution through the range of C8-C20 . However, their adsorption capacities were high in a specific range of C10-C11. The result from the isotherm plot was indicated that surface adsorption of synthesized adsorbent was isotherm type I while the surface adsorption of commercial adsorbent was isotherm type III.

Behavior of mercury in high-temperature vitrification processes

International Nuclear Information System (INIS)

Goles, R.W.; Holton, K.K.; Sevigny, G.J.

1992-01-01

This paper reports that the Pacific Northwest Laboratory (PNL) has evaluated the waste processing behavior of mercury in simulated defense waste. A series of tests were performed under various operating conditions using an experimental-scale liquid-fed ceramic melter (LFCM). This solidification technology had no detectable capacity for incorporating mercury into its product, borosilicate glass. Chemically, the condensed mercury effluent was composed almost entirely of chlorides, and except in a low-temperature test, Hg 2 Cl 2 was the primary chloride formed. As a result, combined mercury accounted for most of the insoluble mass collected by the process quench scrubber. Although macroscopic quantities of elemental mercury were never observed in process secondary waste streams, finely divided and dispersed mercury that blackened all condensed Hg 2 Cl 2 residues was capable of saturating the quenched process exhaust with mercury vapor. The vapor pressure of mercury, however, in the quenched melter exhaust was easily and predictably controlled with the off-gas stream chiller

Selective adsorption behavior of Cd(II) ion imprinted polymers synthesized by microwave-assisted inverse emulsion polymerization: Adsorption performance and mechanism

International Nuclear Information System (INIS)

Zhu, Fang; Li, Luwei; Xing, Junde

2017-01-01

Highlights: • Microwave assisted inverse emulsion polymerization was applied to prepare Cd(II) imprinted polymers. • The adsorption capacity was evaluated by static adsorption experiments. • Pseudo-second-order model and Langmuir adsorption isotherm model had the best agreement with the experimental data. • The adsorption was a spontaneous and endothermic process. • Cd(II) imprinted polymers have specific identification for Cd(II). - Abstract: Microwave-assisted inverse emulsion polymerization method was used to prepare Cd(II) imprinted polymer (IIP) by using β-cyclodextrin (β-CD) and acrylamide (AM) as functional monomer, epichlorohydrin (ECH) as crossing-linking agent, ammonium persulfate as initiator. The Cd(II) imprinted polymer was characterized by SEM, FTIR and TGA. The influences of initial concentration of Cd(II), pH values, temperature, time and competitive ions on adsorption capacity and recognition properties are investigated. Under the optimal conditions, the adsorption capacity could reach 107 mg/g. Furthermore, pseudo first order kinetic model, pseudo second order kinetic model and intra-particular diffusion model were used to describe the adsorption kinetic behavior. Results showed that the pseudo-second-order model (R"2 0.9928–0.9961) had the best agreement with the experimental data. Langmuir adsorption isotherm model described the experimental data well, which indicated that adsorption was mainly monolayer absorption. Moreover, the study of adsorption thermodynamics (ΔG"0 0, ΔS"0 > 0) suggested that the adsorption process was a spontaneous and endothermic process. Competitive selectivity experiment revealed that imprinted polymer could selectively recognize Cd(II). It provides a new idea for removing Cd(II) from aqueous solution.

Study on sorption capacity and characterization of Sr2+ on synthetic zeolite

International Nuclear Information System (INIS)

Wang Jinming; Yi Facheng

2010-01-01

Sr 2+ adsorption capacity of synthetic zeolite(ZF) are studied with the intermittence method, and ZF adsorbed the Sr 2+ is characterized and analyzed by XRD, as a reference for the evaluation of the disposal effectiveness of low and medium radwastes. The results show that Sr 2+ adsorption capacity of ZF is good, and the equilibrium time for ZF to adsorb Sr 2+ is in range of 5-14 days. Sr 2+ concentration has the greatest effect on ZF adsorption capacity,and the medium,temperature and pH value of the solution also have effect on ZF adsorption capacity. With the augment of Sr 2+ concentration,the Sr 2+ equilibrium adsorption quantity of ZF increases,but the equilibrium adsorption rate and equilibrium adsorption ratio decreases. Sr 2+ adsorption capacity of ZF improves with the augment of pH value. Sr 2+ adsorption capacity of ZF is complicate and varies with the different ion, concentration and other components in the medium solution. Sr 2+ adsorption capacity of ZF increases with the augment of temperature. As a whole, when Sr 2+ concentration in the solution is 0.005mol/L, the pH value of the solution, and the temperature of medium and solution have less effect on the Sr 2+ adsorption capacity of ZF, and the unit cell parameter of ZF adsorbed Sr 2+ decreases. (authors)

Activated Carbon Preparation and Modification for Adsorption

Science.gov (United States)

Cao, Yuhe

Butanol is considered a promising, infrastructure-compatible biofuel. Butanol has a higher energy content than ethanol and can be used in conventional gas engines without modifications. Unfortunately, the fermentation pathway for butanol production is restricted by its toxicity to the microbial strains used in the process. Butanol is toxic to the microbes, and this can slow fermentation rates and reduce butanol yields. Gas stripping technology can efficiently remove butanol from the fermentation broth as it is produced, thereby decreasing its inhibitory effects. Traditional butanol separation heavily depends on the energy intensive distillation method. One of the main issues in acetone-butanol-ethanol fermentation is that butanol concentrations in the fermentation broth are low, ranging from 1 to 1.2 percent in weight, because of its toxicity to the microorganisms. Therefore distillation of butanol is even worse than distillation of corn ethanol. Even new separation methods, such as solid- extraction methods involve adding substances, such as polymer resin and zeolite or activated carbon, to biobutanol fermentatioon broth did not achieve energy efficient separation of butanol due to low adsorption selectivity and fouling in broth. Gas-stripping - condensation is another new butanol recovery method, however, the butanol in gas-stripping stream is too low to be condensed without using expensive and energy intensive liquid nitrogen. Adsorption can then be used to recover butanol from the vapor phase. Activated carbon (AC) samples and zeolite were investigated for their butanol vapor adsorption capacities. Commercial activated carbon was modified via hydrothermal H2O2 treatment, and the specific surface area and oxygen-containing functional groups of activated carbon were tested before and after treatment. Hydrothermal H2O 2 modification increased the surface oxygen content, Brunauer-Emmett-Teller surface area, micropore volume, and total pore volume of active carbon

Adsorption of sulfur dioxide on ammonia-treated activated carbon fibers

Science.gov (United States)

Mangun, C.L.; DeBarr, J.A.; Economy, J.

2001-01-01

A series of activated carbon fibers (ACFs) and ammonia-treated ACFs prepared from phenolic fiber precursors have been studied to elucidate the role of pore size, pore volume, and pore surface chemistry on adsorption of sulfur dioxide and its catalytic conversion to sulfuric acid. As expected, the incorporation of basic functional groups into the ACFs was shown as an effective method for increasing adsorption of sulfur dioxide. The adsorption capacity for dry SO2 did not follow specific trends; however the adsorption energies calculated from the DR equation were found to increase linearly with nitrogen content for each series of ACFs. Much higher adsorption capacities were achieved for SO2 in the presence of oxygen and water due to its catalytic conversion to H2SO4. The dominant factor for increasing adsorption of SO2 from simulated flue gas for each series of fibers studied was the weight percent of basic nitrogen groups present. In addition, the adsorption energies calculated for dry SO2 were shown to be linearly related to the adsorption capacity of H2SO4 from this flue gas for all fibers. It was shown that optimization of this parameter along with the pore volume results in higher adsorption capacities for removal of SO2 from flue gases. ?? 2001 Elsevier Science Ltd. All rights reserved.

Functionalized SBA-15 materials for bilirubin adsorption

Science.gov (United States)

Tang, Tao; Zhao, Yanling; Xu, Yao; Wu, Dong; Xu, Jun; Deng, Feng

2011-05-01

To investigate the driving force for bilirubin adsorption on mesoporous materials, a comparative study was carried out between pure siliceous SBA-15 and three functionalized SBA-15 mesoporous materials: CH 3-SBA-15 (MS), NH 2-SBA-15 (AS), and CH 3/NH 2-SBA-15 (AMS) that were synthesized by one-pot method. The obtained materials exhibited large surface areas (553-810 m 2/g) and pore size (6.6-7.1 nm) demonstrated by XRD and N 2-ad/desorption analysis. The SEM images showed that the materials had similar fiberlike morphology. The functionalization extent was calculated according to 29Si MAS NMR spectra and it was close to the designed value (10%). The synthesized mesoporous materials were used as bilirubin adsorbents and showed higher bilirubin adsorption capacities than the commercial active carbon. The adsorption capacities of amine functionalized samples AMS and AS were larger than those of pure siliceous SBA-15 and MS, indicating that electrostatic interaction was the dominant driving force for bilirubin adsorption on mesoporous materials. Increasing the ionic strength of bilirubin solution by adding NaCl would decrease the bilirubin adsorption capacity of mesoporous material, which further demonstrated that the electrostatic interaction was the dominant driving force for bilirubin adsorption. In addition, the hydrophobic interaction provided by methyl groups could promote the bilirubin adsorption.

Adsorptive removal of Cu(II) from aqueous solutions using collagen-tannin resin

Energy Technology Data Exchange (ETDEWEB)

Sun Xia; Huang Xin [Department of Biomass Chemistry and Engineering, Sichuan University, Chengdu 610065 (China); Liao Xuepin, E-mail: xpliao@scu.edu.cn [Department of Biomass Chemistry and Engineering, Sichuan University, Chengdu 610065 (China); National Engineering Laboratory for Clean Technology of Leather Manufacture, Sichuan University, Chengdu 610065 (China); Shi Bi, E-mail: shibi@scu.edu.cn [National Engineering Laboratory for Clean Technology of Leather Manufacture, Sichuan University, Chengdu 610065 (China)

2011-02-28

The collagen-tannin resin (CTR), as a novel adsorbent, was prepared via a reaction of collagen with black wattle tannin and aldehyde, and its adsorption properties to Cu(II) were systematically investigated, including pH effect, adsorption equilibrium, adsorption kinetics, and column adsorption. The adsorption capacity of Cu(II) on CTR was pH-dependent, and it increased with the increase of solution pH. The adsorption isotherms were well described by Langmuir isotherm model with correlating constant (R{sup 2}) higher than 0.99. The adsorption capacity determined at 303 K was high up to 0.26 mmol/g, which was close to the value (0.266 mmol/g) estimated from Langmuir equation. The adsorption capacity was increased with the increase of temperature, and thermodynamic calculations suggested that the adsorption of Cu(II) on CTR is an endothermic process. The adsorption kinetics were well fitted by the pseudo-second-order rate model. Further column studies suggested that CTR was effective for the removal of Cu(II) from solutions, and more than 99% of Cu(II) was desorbed from column using 0.1 mol/L HNO{sub 3} solution. The CTR column can be reused to adsorb Cu(II) without any loss of adsorption capacity.

Supercritical CO2 Assisted Synthesis of EDTA-Fe3O4 Nanocomposite with High Adsorption Capacity for Hexavalent Chromium

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Gunjan Bisht

2016-01-01

Full Text Available Efficiency of EDTA functionalized nanoparticles in adsorption of chromium (VI from water was investigated in this study. Magnetic iron oxide nanoparticles (IONPs were synthesized by a simple chemical coprecipitation route and EDTA coating onto IONPs was attained via supercritical carbon dioxide (Sc CO2, a technology with green sustainable properties. The obtained nanoparticles were then characterized by UV-Visible spectroscopy, Fourier transform infrared spectroscopy (FTIR, X-ray powder diffraction (XRD, transmission electron microscopy (TEM, scanning electron microscopy (SEM, and vibrating magnetometric analysis (VSM. The synthesized nanoparticle and its modified variant were evaluated as adsorbent for chromium (VI removal from water through batch adsorption technique and the effect of analytic concentration; contact time and adsorbent concentration were studied at pH 2. The results showed higher removal efficiency for modified magnetic iron oxide nanoparticles (MIONPs (i.e., 99.9% than their nonmodified variant IONPs, that is, 34.06% for the same concentration after 18 hours of incubation. Also maximum adsorption capacity (qe = 452.26 mg/g of MIONPs attained can be related to their preparation in Sc CO2 as qe calculated from IONPs, that is, 170.33 mg/g, is lower than that of MIONPs. The adsorption data fit well with Freundlich isotherm equation while kinetic adsorption studies of chromium (VI were modeled by pseudo-second-order model.

The experiment of the elemental mercury was removed from natural gas by 4A molecular sieve

Science.gov (United States)

Jiang, Cong; Chen, Yanhao

2018-04-01

Most of the world's natural gas fields contain elemental mercury and mercury compounds, and the amount of mercury in natural gas is generally 1μg/m3 200μg/m3. This paper analyzes the mercury removal principle of chemical adsorption process, the characteristics and application of mercury removal gent and the factors that affect the efficiency of mercury removal. The mercury in the natural gas is adsorbed by the mercury-silver reaction of the 4 molecular sieve after the manned treatment. The limits for mercury content for natural gas for different uses and different treatment processes are also different. From the environmental protection, safety and other factors, it is recommended that the mercury content of natural gas in the pipeline is less than 28μg / m3, and the mercury content of the raw material gas in the equipment such as natural gas liquefaction and natural gas condensate recovery is less than 0.01μg/m3. This paper mainly analyzes the existence of mercury in natural gas, and the experimental research process of using 4A molecular sieve to absorb mercury in natural gas.

[Adsorption characteristics of acetone and butanone onto honeycomb ZSM-5 molecular sieve].

Science.gov (United States)

Du, Juan; Luan, Zhi-Qiang; Xie, Qiang; Ye, Ping-Wei; Li, Kai; Wang, Xi-Qin

2013-12-01

Adsorption capacity of acetone and acetone-butanone mixture onto honeycomb ZSM-5 molecular sieve was measured in this paper, and the influences of relative humidity, initial adsorbate concentration and airflow velocity on the adsorption process were investigated. Besides, adsorption performance parameters were calculated by Wheeler's equation. The results showed that relative humidity had no obvious influence on the acetone adsorption performance, which suggests that this material has good hydrophobic ability; in the low concentration range, the dynamic saturated adsorption capacity of acetone increased with the increase of initial concentration, but in the occasion of high concentration of acetone gas (more than 9 mg x L(-1)), the dynamic saturated adsorption capacity maintained at a certain level and did not vary with the increase of initial concentration; the increase of air flow velocity resulted in significant increase of acetone adsorption rate constant, at the same time the critical layer thickness of the adsorbent bed also increased significantly. In the cases of acetone-butanone mixture, the adsorption capacity of butanone onto ZSM-5 was clearly higher than that of acetone.

Nitrate Adsorption on Clay Kaolin: Batch Tests

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Morteza Mohsenipour

2015-01-01

Full Text Available Soils possessing kaolin, gibbsite, goethite, and hematite particles have been found to have a natural capacity to attenuate pollution in aqueous phase. On the other hand, the hydroxyl group in soil increases anion exchange capacity under a low pH condition. The main objective of this paper was to evaluate effects of kaolin on nitrate reduction under acidic condition. In order to analyze the kaolin adsorption behaviour under various conditions, four different concentrations of nitrate, 45, 112.5, 225, and 450 mgNO3-/L, with a constant pH equal to 2, constant temperature equal to 25°C, and exposure period varying from 0 to 150 minutes were considered. The capacity of nitrate adsorption on kaolin has also been studied involving two well-known adsorption isotherm models, namely, Freundlich and Longmuir. The results revealed that approximately 25% of the nitrate present in the solution was adsorbed on clay kaolin. The laboratory experimental data revealed that Freundlich adsorption isotherm model was more accurate than Longmuir adsorption model in predicting of nitrate adsorption. Furthermore, the retardation factor of nitrate pollution in saturated zone has been found to be approximately 4 in presence of kaolin, which indicated that kaolin can be used for natural scavenger of pollution in the environment.

Selective adsorption behavior of Cd(II) ion imprinted polymers synthesized by microwave-assisted inverse emulsion polymerization: Adsorption performance and mechanism

Energy Technology Data Exchange (ETDEWEB)

Zhu, Fang, E-mail: zhufang@tyut.edu.cn [College of Environmental Science and Engineering, Taiyuan University of Technology, Taiyuan, Shanxi, 030024 (China); Li, Luwei [College of Environmental Science and Engineering, Taiyuan University of Technology, Taiyuan, Shanxi, 030024 (China); Xing, Junde [College of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan, Shanxi, 030024 (China)

2017-01-05

Highlights: • Microwave assisted inverse emulsion polymerization was applied to prepare Cd(II) imprinted polymers. • The adsorption capacity was evaluated by static adsorption experiments. • Pseudo-second-order model and Langmuir adsorption isotherm model had the best agreement with the experimental data. • The adsorption was a spontaneous and endothermic process. • Cd(II) imprinted polymers have specific identification for Cd(II). - Abstract: Microwave-assisted inverse emulsion polymerization method was used to prepare Cd(II) imprinted polymer (IIP) by using β-cyclodextrin (β-CD) and acrylamide (AM) as functional monomer, epichlorohydrin (ECH) as crossing-linking agent, ammonium persulfate as initiator. The Cd(II) imprinted polymer was characterized by SEM, FTIR and TGA. The influences of initial concentration of Cd(II), pH values, temperature, time and competitive ions on adsorption capacity and recognition properties are investigated. Under the optimal conditions, the adsorption capacity could reach 107 mg/g. Furthermore, pseudo first order kinetic model, pseudo second order kinetic model and intra-particular diffusion model were used to describe the adsorption kinetic behavior. Results showed that the pseudo-second-order model (R{sup 2} 0.9928–0.9961) had the best agreement with the experimental data. Langmuir adsorption isotherm model described the experimental data well, which indicated that adsorption was mainly monolayer absorption. Moreover, the study of adsorption thermodynamics (ΔG{sup 0} < 0, ΔH{sup 0} > 0, ΔS{sup 0} > 0) suggested that the adsorption process was a spontaneous and endothermic process. Competitive selectivity experiment revealed that imprinted polymer could selectively recognize Cd(II). It provides a new idea for removing Cd(II) from aqueous solution.

Synthesis of multi-walled carbon nanotubes/{beta}-FeOOH nanocomposites with high adsorption capacity

Energy Technology Data Exchange (ETDEWEB)

Song Haojie, E-mail: shj6922@163.com [School of Materials Science and Engineering, Jiangsu University (China); Liu Lei [Pharmaceutic College of Henan University (China); Jia Xiaohua; Min Chunying [School of Materials Science and Engineering, Jiangsu University (China)

2012-12-15

A hybrid nanostructure of multi-walled carbon nanotubes (CNTs) and {beta}-ferric oxyhydroxide ({beta}-FeOOH) nanoparticles is synthesized by ultrasonic-assisted in situ hydrolysis of the precursor ferric chloride and CNTs. Characterization by X-ray diffraction, scanning electron microscopy , and transmission electron microscopy establishes the nanohybrid structure of the synthesized sample. The results revealed that the surface of CNTs was uniformly assembled by numerous {beta}-FeOOH nanoparticles and had an average diameter of 3 nm. The formation route of anchoring {beta}-FeOOH nanoparticles onto CNTs was proposed as the intercalation and adsorption of iron ions onto the wall of CNTs, followed by the nucleation and growth of {beta}-FeOOH nanoparticles. The values of remanent magnetization (M{sub r}) and coercivity (H{sub c}) of the as-synthesized CNTs/{beta}-FeOOH nanocomposites were 0.1131 emu g, and 490.824 Oe, respectively. Furthermore, CNTs/{beta}-FeOOH nanocomposites showed a very high adsorption capacity of Congo red and thus these nanocomposites can be used as good adsorbents and can be used for the removal of the dye of Congo red from the waste water system.

Adsorption of malachite green and iodine on rice husk-based porous carbon

International Nuclear Information System (INIS)

Guo Yupeng; Zhang Hui; Tao Nannan; Liu Yanhua; Qi Juirui; Wang Zichen; Xu Hongding

2003-01-01

Adsorption isotherms of I 2 and malachite green (MG) by rice husk-based porous carbons (RHCs) from aqueous medium have been studied. Three samples of carbons prepared by NaOH-activation, three samples prepared by KOH-activation and two samples of commercial carbons have been studied. And the adsorption isotherms have been determined after modifying the carbon surfaces by oxidation with nitric acid and hydrogen peroxide and after degassing at 800 deg. C. The results have been found to follow the Freundlich adsorption isotherm. Three samples of N series have larger capacity for removing I 2 and MG from solution compared to that of the tested commercial carbons. The adsorption capacity of I 2 is similar for K series and commercial carbons. And the capacity of commercial carbons for MG is larger than K series. The adsorption capacity of I 2 on oxidation carbons has increased for hydrogen peroxide treatment and decreased for nitric acid, and that of MG is decreased. But the adsorption capacities of I 2 and MG increase on degassing. On the other hand, the adsorption of I 2 increases after modifying the carbon surfaces by HCl without oxidation. Suitable mechanisms have been proposed

Development of TREN dendrimers over mesoporous SBA-15 for CO2 adsorption

International Nuclear Information System (INIS)

Bhagiyalakshmi, Margandan; Park, Sang Do; Cha, Wang Seog; Jang, Hyun Tae

2010-01-01

Mesoporous SBA-15 was synthesized using rice husk ash (RHA) as the silica source and their defective Si-OH groups were grafted with tris(2-aminoethyl) amine (TREN) dendrimers generation through step-wise growth technique. The X-ray diffraction (XRD) and nitrogen adsorption/desorption results of parent SBA-15 obtained from RHA, suggests its resemblance with SBA-15 synthesized using conventional silica sources. Furthermore, the nitrogen adsorption/desorption results of SBA-15/TREN dendrimer generations (G1-G3) illustrates the growth of dendrimer inside the mesopores of SBA-15 and their CO 2 adsorption capacity was determined at 25 deg. C. The maximum CO 2 adsorption capacity of 5-6 and 7-8 wt% over second and third dendrimer generation was observed which is discernibly higher than the reported melamine and PAMAM dendrimers. The experimental CO 2 adsorption capacity was found to be less than theoretically calculated CO 2 adsorption capacity due to inter and intra molecular amidation as result of steric hindrance during the dendrimer growth. These SBA-15/TREN dendrimer generations also exhibit thermal stability up to 350 deg. C and CO 2 adsorption capacity remains unaltered upon seven consecutive runs.

Paraquat adsorption on NaX and Al-MCM-41.

Science.gov (United States)

Rongchapo, Wina; Deekamwong, Krittanun; Loiha, Sirinuch; Prayoonpokarach, Sanchai; Wittayakun, Jatuporn

2015-01-01

The aim of this work is to determine paraquat adsorption capacity of zeolite NaX and Al-MCM-41. All adsorbents were synthesized by hydrothermal method using rice husk silica. For Al-MCM-41, aluminum (Al) was added to the synthesis gel of MCM-41 with Al content of 10, 15, 20 and 25 wt%. The faujasite framework type of NaX and mesoporous characteristic of Al-MCM-41 were confirmed by X-ray diffraction. Surface area of all adsorbents determined by N2 adsorption-desorption analysis was higher than 650 m2/g. Al content and geometry were determined by X-ray fluorescence and 27Al nuclear magnetic resonance, respectively. Morphology of Al-MCM-41 were studied by transmission electron microscopy; macropores and defects were observed. The paraquat adsorption experiments were conducted using a concentration range of 80-720 mg/L for NaX and 80-560 mg/L for Al-MCM-41. The paraquat adsorption isotherms from all adsorbents fit well with the Langmuir model. The adsorption capacity of NaX was 120 mg/g-adsorbent. Regarding Al-MCM-41, the 10% Al-MCM-41 exhibited the lowest capacity of 52 mg/g-adsorbent while the other samples had adsorption capacity of 66 mg/g-adsorbent.

Catalysts for oxidation of mercury in flue gas

Science.gov (United States)

Granite, Evan J [Wexford, PA; Pennline, Henry W [Bethel Park, PA

2010-08-17

Two new classes of catalysts for the removal of heavy metal contaminants, especially mercury (Hg) from effluent gases. Both of these classes of catalysts are excellent absorbers of HCl and Cl.sub.2 present in effluent gases. This adsorption of oxidizing agents aids in the oxidation of heavy metal contaminants. The catalysts remove mercury by oxidizing the Hg into mercury (II) moieties. For one class of catalysts, the active component is selected from the group consisting of iridium (Ir) and iridum-platinum (Ir/Pt) alloys. The Ir and Ir/Pt alloy catalysts are especially corrosion resistant. For the other class of catalyst, the active component is partially combusted coal or "Thief" carbon impregnated with Cl.sub.2. Untreated Thief carbon catalyst can be self-activating in the presence of effluent gas streams. The Thief carbon catalyst is disposable by means of capture from the effluent gas stream in a particulate collection device (PCD).

Adsorption decontamination of radioactive waste solvent by activated alumina and bauxites

International Nuclear Information System (INIS)

Hassan, N.M.; Marra, J.C.; Kyser, E.A.

1994-01-01

An adsorption process utilizing activated alumina and activated bauxite adsorbents was evaluated as a function of operating parameters for the removal of low level radioactive contaminants from organic waste solvent generated in the fuel reprocessing facilities and support operations at Savannah River Site. The waste solvent, 30% volume tributyl phosphate in n-paraffin diluent, was degraded due to hydrolysis and radiolysis reactions of tributyl phosphate and n-paraffin diluent, producing fission product binding degradation impurities. The process, which has the potential for removing these activity-binding degradation impurities from the solvent, was operated downflow through glass columns packed with activated alumina and activated bauxite adsorbents. Experimental breakthrough curves were obtained under various operating temperatures and flow rates. The results show that the adsorption capacity of the activated alumina was in the order 10 4 dpm/g and the capacity of the activated bauxite was 10 5 dpm/g. The performance of the adsorption process was evaluated in terms of dynamic parameters (i.e. adsorption capacity, the height and the efficiency of adsorption zone) in such a way as to maximize the adsorption capacity and to minimize the height of the mass transfer or adsorption zone

Adsorption of Phosphate Ion in Water with Lithium-Intercalated Gibbsite

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Riwandi Sihombing

2015-12-01

Full Text Available In order to enhance adsorption capacity of gibbsite (Al(OH3 as an adsorbent for the adsorption of phosphate in water, gibbsite was modified through lithium-intercalation. The purification method of Tributh and Lagaly was applied prior to intercalation. The Li-Intercalation was prepared by the dispersion of gibbsite into LiCl solution for 24 hours. This intercalation formed an cationic clay with the structure of [LiAl2(OH6]+ and exchangeable Cl- anions in the gibbsite interlayer. A phosphate adsorption test using Lithium-intercalated gibbsite (LIG resulted in optimum adsorption occurring at pH 4.5 with an adsorption capacity of 11.198 mg phosphate/g LIG which is equivalent with 1.04 wt% LIG. The adsorption capacity decreased with decreasing amounts of H2PO4-/HPO4- species in the solution. This study showed that LIG has potential as an adsorbent for phosphate in an aqueous solution with pH 4.5–9.5.

Influence of organobentonite structure on toluene adsorption from water solution

Directory of Open Access Journals (Sweden)

Nuria Vidal

2012-12-01

Full Text Available Due to increase water pollution by organic compound derived from hydrocarbons such as toluene, several alternative technologies for remediation of polluted water have been originated. In this work natural bentonites were modified with cetyltrimethylammonium (CTMA+ for obtaining organophilic bentonites. The obtained CTMA-bentonites would be suitable for use as adsorbents of toluene present in water. The influence of structural characteristics of CTMA-bentonites on their adsorption capacity was studied. It was shown that adsorption of toluene depended on homogeneous interlayer space associated with arrangements of CTMA+ paraffin-monolayer and bilayer models, accompanied by a high degree ordering of the carbon chain of organic cation in both arrangements. However, packing density would not have an evident influence on the retention capacity of these materials. The solids obtained were characterized by chemical analysis, X-ray diffractions and infrared spectroscopy. Toluene adsorption was measured by UV-visible spectrophotometer. Adsorption capacity was studied by determining adsorption isotherms and adsorption coefficient calculation. The adsorption isotherms were straight-line indicating a partition phenomenon of toluene between the aqueous and organic phase present in organophilic bentonites.

Adsorption of Hg2+ from aqueous solution onto polyacrylamide/attapulgite

International Nuclear Information System (INIS)

Zhao Yijiang; Chen Yan; Li Meisheng; Zhou Shouyong; Xue Ailian; Xing Weihong

2009-01-01

Polyacrylamide/attapulgite (PAM/ATP) was prepared by the solution polymerization of acrylamide (AM) onto γ-methacryloxypropyl trimethoxy silane (KH-570)-modified attapulgite (ATP). PAM/ATP was characterized using Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS). The effects of contact time, adsorbent dosage, and pH of the initial solution on the adsorption capacities for Hg 2+ were investigated. The adsorption process was rapid; 88% of adsorption occurred within 5 min and equilibrium was achieved at around 40 min. The equilibrium data fitted the Langmuir sorption isotherms well, and the maximum adsorption capacity of Hg 2+ onto PAM/ATP was found to be 192.5 mg g -1 . The adsorption kinetics of PAM/ATP fitted a pseudo-second-order kinetic model. Our results suggest that chemisorption processes could be the rate-limiting steps in the process of Hg 2+ adsorption. Hg 2+ adsorbed onto PAM/ATP could be effectively desorbed in hot acetic acid solution, and the adsorption capacity of the regenerated adsorbents could still be maintained at 95% by the sixth cycle.

Determination of Xanthine in the Presence of Hypoxanthine by Adsorptive Stripping Voltammetry at the Mercury Film Electrode

Directory of Open Access Journals (Sweden)

Percio Augusto Mardini Farias

2014-01-01

Full Text Available A stripping method for the determination of xanthine in the presence of hypoxanthine at the submicromolar concentration levels is described. The method is based on controlled adsorptive accumulation at the thin-film mercury electrode followed by a fast linear scan voltammetric measurement of the surface species. Optimum experimental conditions were found to be the use of 1.0 × 10 −3 mol L −1 NaOH solution as supporting electrolyte, an accumulation potential of 0.00 V for xanthine and −0.50 V for hypoxanthine–copper, and a linear scan rate of 200 mV second −1 . The response of xanthine is linear over the concentration ranges of 20-140 ppb. For an accumulation time of 30 minutes, the detection limit was found to be 36 ppt (2.3 × 10 −10 mol L −1 . Adequate conditions for measuring the xanthine in the presence of hypoxanthine, copper and other metals, uric acid, and other nitrogenated bases were also investigated. The utility of the method is demonstrated by the presence of xanthine associated with hypoxanthine, uric acid, nitrogenated bases, ATP, and ssDNA.

Adsorption of Copper Ion using Acrylic Acid-g-Polyaniline in Aqueous Solution

Science.gov (United States)

Kamarudin, Sabariah; Mohammad, Masita

2018-04-01

A conductive polymer, polyaniline (PANI) has unique electrical behaviour, stable in the environment, easy synthesis and have wide application in various fields. Modification of PANI in order to improve its adsorption capacity has been done. In this study, the polyaniline-grafted acrylic acid has been prepared and followed by adsorption of copper ion in aqueous solution. Acrylic acid, PANI and acrylic acid-g-polyaniline (Aag-PANI) were characterized by FTIR and SEM to determine its characteristic. The adsorption capacity was investigated to study the removal capacity of Cu ion from aqueous solution. Two parameters were selected which are pH (2, 4 and 6) and initial metal ion concentration (50 mg/L, 100 mg/L and 200 mg/L). The maximum adsorption capacity for PANI and Aag-PANI are 1.7 mg/g and 64.6 mg/g, respectively, at an initial concentration of 100 mg/L. The Langmuir adsorption isotherm model and Freundlich adsorption isotherm model have been used and showed that it is heterolayer adsorption by follows the Freundlich isotherm model.

On thermodynamics of methane+carbonaceous materials adsorption

KAUST Repository

Rahman, Kazi Afzalur; Chakraborty, Anutosh; Saha, Bidyut Baran; Ng, Kim Choon

2012-01-01

This study presents the theoretical frameworks for the thermodynamic quantities namely the heat of adsorption, specific heat capacity, entropy, and enthalpy for the adsorption of methane onto various carbonaceous materials. The proposed theoretical

Analysis for trace mercury concentration. I. Critical evaluation of current procedures. II. A proposed method for determination by instrumental neutron activation analysis

International Nuclear Information System (INIS)

Litman, R.

1975-01-01

Current methods of sample pretreatments, digestion, lyophilization and extraction, have been found to lead to considerable loss of mercury, at an initial mercury concentration of 1 μg/g, and less. Storage of solutions of mercury at concentrations of less than 1 μg/ml, in glass, Teflon and polyethylene containers, leads to losses by adsorption. Electrochemical reduction of mercury to the metal, and subsequent volatilization, is postulated as the mechanism of loss from the samples studied during lyophilization. A method of instrumental neutron activation analysis, which obviates the above pretreatments, has been developed for mercury concentrations as low as 1 ng/ml

EURISOL-DS METEX: Cooling and Temperature Control of the Mercury Loop

CERN Document Server

Stefan Joray

The cooling of the mercury loop is described on pages two, three and four. The gaps in the water jackets of the heat exchangers are too large and the cooling water capacity is too low. Convection from the wall into water is bad. The mercury temperature is too high. On page five is a proposal how the mercury temperature can be kept low and constant.

玉米秸秆基改性生物质活性炭对Cd的吸附特性%Adsorption capacity of modified corn straw based activated biocarbon to Cd

Institute of Scientific and Technical Information of China (English)

吐尔逊·吐尔洪; 帕提古丽·伊克木; 阿热祖古丽·达吾提; 阿马努拉·依明尼亚孜

2018-01-01

以玉米秸秆为原料,制备了生物质活性炭(以下简称生物炭),用HNO3、NaOH、沸水、四氢呋喃(THF)对其进行改性,并比较了不同生物炭对Cd的吸附特性,对沸水和 T HF滤液进行了光谱分析,结果显示:随着Cd初始浓度的增加,玉米秸秆基生物炭及改性产物对Cd的吸附量大体增强;Cd初始质量浓度超过25.0 mg/L时,吸附量表现为碱改性生物炭> 未改性生物炭> T HF改性生物炭> 沸水改性生物炭> 酸改性生物炭.NaO H通过改变玉米秸秆基生物炭表面官能团和元素构成,增强了其吸附能力.HNO3使玉米秸秆基生物炭孔隙带正电荷,从而抑制了对Cd的吸附.沸水和 T HF从玉米秸秆基生物炭孔隙中溶出了有利于吸附反应的部分表面官能团,从而降低了其对Cd的吸附能力.随着Cd初始浓度增加,玉米秸秆基生物炭对Cd的吸附量大体增加,滤液pH大体降低.用玉米秸秆基生物炭处理污水中的Cd时,建议用碱改性法来提高其吸附能力.%Corn straw based activated biocarbon was prepared and modified with HNO3,NaOH,hot water and tetrahydrofuran(T HF).Adsorption capacities of original and modified activated biocarbons to Cd,as well as spectrum of filtrate of hot water and THF modified activated biocarbons were tested.Result showed that adsorption capacities of activated biocarbons increased with the concentration of initial Cd solution.The order of adsorption capacities was NaOH modified activated biocarbons>original activated biocarbons> THF modified activated biocarbons >hot water modified activated biocarbons > HNO3modified activated biocarbons when initial Cd exceeded 25.0 mg/L.NaOH enhanced the adsorption capacity of original activated biocarbon by changing the surface functional group and elemental contents.HNO3inhibited the adsorption by charging the surface of activated biocarbon with positive charge.Hot water and THF scoured off some surface groups which were favorable for adsorption

Supercritical CO2 Assisted Synthesis of EDTA-Fe3O4 Nano composite with High Adsorption Capacity for Hexavalent Chromium

International Nuclear Information System (INIS)

Bisht, G.; Neupane, S.; Makaju, R.

2016-01-01

Efficiency of EDTA functionalized nanoparticles in adsorption of chromium (Vi) from water was investigated in this study. Magnetic iron oxide nanoparticles (IONPs) were synthesized by a simple chemical coprecipitation route and EDTA coating onto IONPs was attained via supercritical carbon dioxide (Sc CO 2 ), a technology with green sustainable properties. The obtained nanoparticles were then characterized by UV-Visible spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and vibrating magnetometric analysis (VSM). The synthesized nanoparticle and its modified variant were evaluated as adsorbent for chromium (Vi) removal from water through batch adsorption technique and the effect of analytic concentration; contact time and adsorbent concentration were studied at ph 2. The results showed higher removal efficiency for modified magnetic iron oxide nanoparticles (MIONPs) (i.e., 99.9%) than their non modified variant IONPs, that is, 34.06% for the same concentration after 18 hours of incubation. Also maximum adsorption capacity (q e = 452.26 mg/g) of MIONPs attained can be related to their preparation in Sc CO 2 asq e calculated from IONPs, that is, 170.33 mg/g, is lower than that of MIONPs. The adsorption data fit well with Freundlich isotherm equation while kinetic adsorption studies of chromium (Vi) were modeled by pseudo-second-order model

Adsorption isotherms and kinetics for dibenzothiophene on activated

Indian Academy of Sciences (India)

Adsorption isotherms were obtained and desulphurization kinetics were carried out on solutions of dibenzothiophene (DBT) and thiophene in a model fuel. The efficiencies of DBT and thiophene removal were reported. The adsorption isotherms fitted the Langmuir and Freundlich models. The highest adsorption capacity for ...

Understanding mercury binding on activated carbon

Energy Technology Data Exchange (ETDEWEB)

Padak, B.; Wilcox, J. [Stanford University, Stanford, CA (United States)

2009-10-15

Understanding the mechanism by which mercury adsorbs on activated carbon is crucial to the design and fabrication of effective capture technologies. In this study, the possible binding mechanism of mercury (Hg) and its species, i.e., HgCl and HgCl{sub 2} on activated carbon is investigated using ab initio-based energetic calculations. The activated carbon surface is modeled by a single graphene layer in which the edge atoms on the upper side are unsaturated in order to simulate the active sites. in some cases, chlorine atoms are placed at the edge sites to examine the effect of chlorine on the binding of Hg, HgCl and HgCl{sub 2}. It has been concluded that both HgCl and HgCl{sub 2} can be adsorbed dissociatively or non-dissociatively. In the case of dissociative adsorption, it is energetically favorable for atomic Hg to desorb and energetically favorable for it to remain on the surface in the Hg{sup 1+} state, HgCl. The Hg{sup 2+}, oxidized compound, HgCl2 was not found to be stable on the surface. The most probable mercury species on the surface was found to be HgCl.

Mercury emission, control and measurement from coal combustion

Energy Technology Data Exchange (ETDEWEB)

Pan, Wei-Ping [North China Electric Power Univ., Beijing (China). School of Energy and Power Engineering; Western Kentucky Univ., Bowling Green, KY (United States). Inst. for Combustion Science and Environmental Technology; Cao, Yan [Western Kentucky Univ., Bowling Green, KY (United States). Inst. for Combustion Science and Environmental Technology; Zhang, Kai [North China Electric Power Univ., Beijing (China). School of Energy and Power Engineering

2013-07-01

that are only equipped with an Electrostatic Precipitator (ESP) have to look for a control method to reduce mercury emission. So far, the most economical method has been active carbon or sorbent injection before the ESP. Active carbon or sorbent injected into the flue gas ducts to oxidize the elemental mercury and then the oxidized mercury will be captured from the flue gas, then the ESP captures the active carbon or sorbent and fly ash simultaneously. Therefore, the long distance transportation of gaseous mercury is eliminated. However, the capture efficiency of mercury is extremely important in order to reduce the increase in ESP load and control the cost. The oxidation and adsorption rate of HBr and fly ash will be discussed in this presentation.

Fluorocarbon Adsorption in Hierarchical Porous Frameworks

Energy Technology Data Exchange (ETDEWEB)

Motkuri, Radha K.; Annapureddy, Harsha V.; Vijayakumar, M.; Schaef, Herbert T.; Martin, P F.; McGrail, B. Peter; Dang, Liem X.; Krishna, Rajamani; Thallapally, Praveen K.

2014-07-09

The adsorption behavior of a series of fluorocarbon derivatives was examined on a set of microporous metal organic framework (MOF) sorbents and another set of hierarchical mesoporous MOFs. The microporous M-DOBDC (M = Ni, Co) showed a saturation uptake capacity for R12 of over 4 mmol/g at a very low relative saturation pressure (P/Po) of 0.02. In contrast, the mesoporous MOF MIL-101 showed an exceptionally high uptake capacity reaching over 14 mmol/g at P/Po of 0.4. Adsorption affinity in terms of mass loading and isosteric heats of adsorption were found to generally correlate with the polarizability of the refrigerant with R12 > R22 > R13 > R14 > methane. These results suggest the possibility of exploiting MOFs for separation of azeotropic mixtures of fluorocarbons and use in eco-friendly fluorocarbon-based adsorption cooling and refrigeration applications.

Competitive Adsorption of Chloroform and Bromoform Using ...

African Journals Online (AJOL)

The results obtained were checked with Freundlich adsorption isotherm model. This model expresses well adsorption of one THM species in the presence of another with R2 > 0.95. Based on the model, adsorption capacity of Calgon F200 and Norit GCN1240 were found higher for bromoform than chloroform. Calgon F200 ...

Formation of nanocolloidal metacinnabar in mercury-DOM-sulfide systems

Science.gov (United States)

Gerbig, Chase A.; Kim, Christopher S.; Stegemeier, John P.; Ryan, Joseph N.; Aiken, George R.

2011-01-01

Direct determination of mercury (Hg) speciation in sulfide-containing environments is confounded by low mercury concentrations and poor analytical sensitivity. Here we report the results of experiments designed to assess mercury speciation at environmentally relevant ratios of mercury to dissolved organic matter (DOM) (i.e., structure (EXAFS) spectroscopy. Aqueous Hg(II) and a DOM isolate were equilibrated in the presence and absence of 100 μM total sulfide. In the absence of sulfide, mercury adsorption to the resin increased as the Hg:DOM ratio decreased and as the strength of Hg-DOM binding increased. EXAFS analysis indicated that in the absence of sulfide, mercury bonds with an average of 2.4 ± 0.2 sulfur atoms with a bond length typical of mercury-organic thiol ligands (2.35 Å). In the presence of sulfide, mercury showed greater affinity for the C18 resin, and its chromatographic behavior was independent of Hg:DOM ratio. EXAFS analysis showed mercury–sulfur bonds with a longer interatomic distance (2.51–2.53 Å) similar to the mercury–sulfur bond distance in metacinnabar (2.53 Å) regardless of the Hg:DOM ratio. For all samples containing sulfide, the sulfur coordination number was below the ideal four-coordinate structure of metacinnabar. At a low Hg:DOM ratio where strong binding DOM sites may control mercury speciation (1.9 nmol mg–1) mercury was coordinated by 2.3 ± 0.2 sulfur atoms, and the coordination number rose with increasing Hg:DOM ratio. The less-than-ideal coordination numbers indicate metacinnabar-like species on the nanometer scale, and the positive correlation between Hg:DOM ratio and sulfur coordination number suggests progressively increasing particle size or crystalline order with increasing abundance of mercury with respect to DOM. In DOM-containing sulfidic systems nanocolloidal metacinnabar-like species may form, and these species need to be considered when addressing mercury biogeochemistry.

Potential theory of adsorption for associating mixtures: possibilities and limitations

DEFF Research Database (Denmark)

Bjørner, Martin Gamel; Shapiro, Alexander; Kontogeorgis, Georgios

2013-01-01

The applicability of the Multicomponent Potential Theory of Adsorption (MPTA) for prediction of the adsorption equilibrium of several associating binary mixtures on different industrial adsorbents is investigated. In the MPTA the adsorbates are considered to be distributed fluids subject...... to describe the solid-fluid interactions. The potential is extended to include adsorbate-absorbent specific capacities rather than an adsorbent specific capacity. Correlations of pure component isotherms are generally excellent with individual capacities, although adsorption on silicas at different...... temperatures still poses a challenge. The quality of the correlations is usually independent on the applied EoS. Predictions for binary mixtures indicate that the MPTA+SRK is superior when adsorption occurs on non-polar or slightly polar adsorbents, while MPTA+CPA performs better for polar adsorbents, or when...

Evaluation of the adsorption capacity of nano-graphene and nano-graphene oxide for xylene removal from air and their comparison with the standard adsorbent of activated carbon to introduce the optimized one

Directory of Open Access Journals (Sweden)

Akram Tabrizi

2016-06-01

Full Text Available Introduction: Volatile organic compounds from industrial activities are one of the most important pollutants released into the air and have adverse effects on human and environment. Therefore, they should be removed before releasing into atmosphere. The aim of the study was to evaluate xylene removal from air by nano-grapheme and nano-graphene oxide in comparison with activated carbon adsorbent. Material and Method:  After preparing adsorbents of activated carbon, nano-graphene, and nano-graphene oxide, experiments adsorption capacity in static mode (Batch were carried out in a glass vial. Some variables including contact time, the amount of adsorbent, the concentration of xylene, and the temperature were studied. Langmuir absorption isotherms were used in order to study the adsorption capacity of xylene on adsorbents. Moreover, sample analysis was done by gas chromatography with Flame Ionization Detector (GC-FID. Results: The adsorption capacities of activated carbon, nano-graphene oxide and nano-graphene for removal of xylene were obtained 349.8, 14.5, and 490 mg/g, respectively. The results of Scanning Electron Microscope (SEM for nano-graphene and nano-graphene oxide showed particle size of less than 100 nm. While, the results of Transmission Electron Microscope (TEM showed particle size of 45nm for nano-graphene and 65 nm for nano-graphene oxide. Also, X-Ray Diffraction (XRD showed cube structure of nano-adsorbents. Conclusion: In constant humidity, increase in exposure time and temperature caused an increase in the adsorption capacity. The results revealed greater adsorption capacity of xylene removal for nano-graphene compared to the activated carbon, and nano-graphene oxide.

Mercury

International Nuclear Information System (INIS)

Vilas, F.; Chapman, C.R.; Matthews, M.S.

1988-01-01

Papers are presented on future observations of and missions to Mercury, the photometry and polarimetry of Mercury, the surface composition of Mercury from reflectance spectrophotometry, the Goldstone radar observations of Mercury, the radar observations of Mercury, the stratigraphy and geologic history of Mercury, the geomorphology of impact craters on Mercury, and the cratering record on Mercury and the origin of impacting objects. Consideration is also given to the tectonics of Mercury, the tectonic history of Mercury, Mercury's thermal history and the generation of its magnetic field, the rotational dynamics of Mercury and the state of its core, Mercury's magnetic field and interior, the magnetosphere of Mercury, and the Mercury atmosphere. Other papers are on the present bounds on the bulk composition of Mercury and the implications for planetary formation processes, the building stones of the planets, the origin and composition of Mercury, the formation of Mercury from planetesimals, and theoretical considerations on the strange density of Mercury

Adsorption methods for hydrogen isotope storage on zeolitic sieves

International Nuclear Information System (INIS)

Cristescu, Ioana; Cristescu, Ion; Vasut, F.; Brad, S.; Lazar, A.

2001-01-01

For hydrogen isotope separation, adsorption molecular sieves and active carbon were used. Adsorption process proceeds at liquid nitrogen and liquid hydrogen temperatures. Commercial zeolites have the same proprieties with natural zeolites, but they have a regular pore structure. They also have affinity for molecules of different size with defined shapes. Experimental results obtained at liquid nitrogen temperature (77.4 K) and liquid hydrogen revealed the efficient behaviour of the active carbon and zeolitic sieves for hydrogen isotopes temporary storage. We study adsorption of the synthetic zeolites in a wide range of temperatures and pressures and we used the molecular sieves 4A, 5A and active carbon. The 4A and 5A zeolites have a tridimensional structure with 11.4 A diameter. When the hydration water is eliminated, the material keeps a porous structure. The porous volume represents 45% from the zeolite mass for 4A and 5A sieves. The activation temperature of the zeolite and the carbon is very important for obtaining a high adsorption capacity. If the temperature used for activation is low, the structural water will be not eliminated and the adsorption capacity will be low. The excessive temperature will destroy the porous structure. The adsorption capacity for the hydrogen isotopes was calculated with the relation: A = V ads /m (cm 3 /g). The adsorption capacity and efficiency for the adsorbent materials, are given. Physical adsorption process of the hydrogen isotopes was carried out at liquid nitrogen temperature. The flux gas used in the adsorption system is composed of dry deuterium and protium. This mixture is cooled in liquid nitrogen and then is passed to the adsorbent getter at the same temperature (77.4 K). The gas flux in the adsorbent getter is 5 and 72 l/h (which correspond to 0.008 and 0.134 discharge velocity, respectively). (authors)

Adsorption of tannic acid from aqueous solution onto surfactant-modified zeolite

Energy Technology Data Exchange (ETDEWEB)

Lin, Jianwei, E-mail: jwlin@shou.edu.cn [College of Marine Science, Shanghai Ocean University, No. 999 Hucheng Huan Road, Pudong District, Shanghai 201306 (China); Zhan, Yanhui; Zhu, Zhiliang [State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai 200092 (China); Xing, Yunqing [College of Marine Science, Shanghai Ocean University, No. 999 Hucheng Huan Road, Pudong District, Shanghai 201306 (China)

2011-10-15

Graphical abstract: Surfactant-modified zeolites (SMZs) with various loadings of cetylpyridinium bromide (CPB) were used as adsorbents to remove tannic acid (TA) from aqueous solution. Highlights: {yields} Surfactant modified zeolites (SMZs) have a good tannic acid (TA) adsorption capacity. {yields} Adsorption capacity for SMZ with bilayer was relatively high at solution pH 3.5-7.0. {yields} Adsorption was well described by pseudo-second-order kinetic model. {yields} Adsorption fitted well with Langmuir, Redlich-Peterson and Sips isotherm models. {yields} Coexisting Cu(II) in aqueous solution resulted in markedly enhanced TA adsorption. - Abstract: Surfactant-modified zeolites (SMZs) with various loadings of cetylpyridinium bromide (CPB) were used as adsorbents to remove tannic acid (TA) from aqueous solution. The TA adsorption efficiencies for natural zeolite and various SMZs were compared. SMZ presented higher TA adsorption efficiency than natural zeolite, and SMZ with higher loading amount of CPB exhibited higher TA adsorption efficiency. The adsorption of TA onto SMZ as a function of contact time, initial adsorbate concentration, temperature, ionic strength, coexisting Cu(II) and solution pH was investigated. The adsorbents before and after adsorption were characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), thermogravimetric analysis (TGA), and Fourier transform infrared (FT-IR) spectroscopy. The adsorption kinetics of TA onto SMZ with CPB bilayer coverage (SMZ-CBC) followed a pseudo-second-order model. The equilibrium adsorption data of TA onto SMZ-CBC were well represented by Langmuir, Redlich-Peterson and Sips isotherm models. The calculated thermodynamic parameters indicated that TA adsorption onto SMZ-CBC was spontaneous and exothermic. The TA adsorption capacity for SMZ-CBC slightly decreased with increasing ionic strength but significantly increased with increasing Cu(II) concentration. The TA adsorption

Combined paracetamol and amitriptyline adsorption to activated charcoal

DEFF Research Database (Denmark)

Hoegberg, Lotte Christine Groth; Groenlykke, Thor Buch; Abildtrup, Ulla

2010-01-01

Objectives. High-gram drug doses seen in multiple-drug poisonings might be close to the adsorption capacity of activated charcoal (AC). The aim was to determine the maximum adsorption capacities (Q(m)) of amitriptyline and paracetamol, separately and in combination, to AC. Methods. ACs (Carbomix......® and Norit Ready-To-Use) were tested in vitro. At pH 1.2 and pH 7.2, 0.250 g AC and paracetamol and/or amitriptyline were mixed and incubated. The AC: drug ratios were 10:1, 5:1, 3:1, 2:1, and 1:1. The mixed-drug adsorption vials contained the same AC: paracetamol ratios, but amitriptyline was added as fixed...... Ready-To-Use. The tested pH differences had minor effect on the adsorption. The mixed-drug adsorption showed about 40% Q(m) reduction of each drug with increasing amounts of drug/g AC, but the total gram of drug adsorbed to AC was increased compared to one-drug conditions. Conclusion. The adsorption...

Adsorptive Removal and Adsorption Kinetics of Fluoroquinolone by Nano-Hydroxyapatite.

Directory of Open Access Journals (Sweden)

Yajun Chen

Full Text Available Various kinds of antibiotics, especially fluoroquinolone antibiotics (FQs have been widely used for the therapy of infectious diseases in human and livestock. For their poorly absorbed by living organisms, large-scale misuse or abuse of FQs will foster drug resistance among pathogenic bacteria, as well as a variety of environmental problems when they were released in the environment. In this work, the adsorption properties of two FQs, namely norfloxacin (NOR and ciprofloxacin (CIP, by nano-hydroxyapatite (n-HAP were studied by batch adsorption experiments. The adsorption curves of FQs by n-HAP were simulated by Langmuir and Freundlich isotherms. The results shown that NOR and CIP can be adsorbed effectively by the adsorbent of n-HAP, and the adsorption capacity of FQs increase with increasing dosage of n-HAP. The optimum dosage of n-HAP for FQs removal was 20 g · L(-1, in which the removal efficiencies is 51.6% and 47.3%, and an adsorption equilibrium time is 20 min. The maximum removal efficiency occurred when pH is 6 for both FQs. The adsorption isotherm of FQs fits well for both Langmuir and Freundlich equations. The adsorption of both FQs by n-HAP follows second-order kinetics.

Adsorptive Removal and Adsorption Kinetics of Fluoroquinolone by Nano-Hydroxyapatite

Science.gov (United States)

Chen, Yajun; Lan, Tao; Duan, Lunchao; Wang, Fenghe; Zhao, Bin; Zhang, Shengtian; Wei, Wei

2015-01-01

Various kinds of antibiotics, especially fluoroquinolone antibiotics (FQs) have been widely used for the therapy of infectious diseases in human and livestock. For their poorly absorbed by living organisms, large-scale misuse or abuse of FQs will foster drug resistance among pathogenic bacteria, as well as a variety of environmental problems when they were released in the environment. In this work, the adsorption properties of two FQs, namely norfloxacin (NOR) and ciprofloxacin (CIP), by nano-hydroxyapatite (n-HAP) were studied by batch adsorption experiments. The adsorption curves of FQs by n-HAP were simulated by Langmuir and Freundlich isotherms. The results shown that NOR and CIP can be adsorbed effectively by the adsorbent of n-HAP, and the adsorption capacity of FQs increase with increasing dosage of n-HAP. The optimum dosage of n-HAP for FQs removal was 20 g·L-1, in which the removal efficiencies is 51.6% and 47.3%, and an adsorption equilibrium time is 20 min. The maximum removal efficiency occurred when pH is 6 for both FQs. The adsorption isotherm of FQs fits well for both Langmuir and Freundlich equations. The adsorption of both FQs by n-HAP follows second-order kinetics. PMID:26698573

Kinetic modelling and mechanism of dye adsorption on unburned carbon

Energy Technology Data Exchange (ETDEWEB)

Wang, S.B.; Li, H.T. [Curtin University of Technology, Perth, WA (Australia). Dept. of Chemical Engineering

2007-07-01

Textile dyeing processes are among the most environmentally unfriendly industrial processes by producing coloured wastewaters. The adsorption method using unburned carbon from coal combustion residue was studied for the decolourisation of typical acidic and basic dyes. It was discovered that the unburned carbon showed high adsorption capacity at 1.97 x 10{sup -4} and 5.27 x 10{sup -4} mol/g for Basic Violet 3 and Acid Black 1, respectively. The solution pH, particle size and temperature significantly influenced the adsorption capacity. Higher solution pH favoured the adsorption of basic dye while reduced the adsorption of acid dye. The adsorption of dye increased with increasing temperature but decreased with increasing particle size. Sorption kinetic data indicated that the adsorption kinetics followed the pseudo-second-order model. The adsorption mechanism consisted of two processes, external diffusion and intraparticle diffusion, and the external diffusion was the dominating process.

Influence of alumina phases on the molybdenum adsorption capacity and chemical stability for {sup 99}Mo/{sup 99m}Tc generators columns

Energy Technology Data Exchange (ETDEWEB)

Guedes-Silva, Cecilia C.; Ferreira, Thiago dos Santos; Paula, Carolina M. de; Otubo, Larissa, E-mail: cecilia.guedes@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Carvalho, Flavio M.S. [Universidade de Sao Paulo (IGC/USP), SP (Brazil). Instituto de Geociencias

2016-07-15

Technetium-{sup 99m} is the clinically most used radionuclide worldwide. Although many techniques can be applied to separate {sup 99}Mo and {sup 99m}Tc, the most commonly used method is the column chromatography with alumina as stationary phase. However, the alumina nowadays used has limited adsorption capacity of molybdate ions which implies the need to develop or improve materials to produce high specific activity generators. In this paper, alumina was obtained by a solid state method and heat treatments at different conditions. The powders had a microstructure with porous particles of γ, δ, θ and α-Al{sub 2}O{sub 3} phases as well as specific surface area between 36 and 312 m{sup 2} g{sup -1}. Most interesting results were reached by powders calcined at 900 deg C for 5 hours which had high chemical stability and a molybdenum adsorption capacity of 92.45 mg Mo per g alumina. (author)

Adsorption properties of Congo Red from aqueous solution onto surfactant-modified montmorillonite

International Nuclear Information System (INIS)

Wang Li; Wang Aiqin

2008-01-01

A series of surfactant-modified montmorillonites (MMT) were prepared using octyltrimethylammonium bromide (OTAB), dodecyltrimethylammonium bromide (DTAB), cetyltrimethylammonium bromide (CTAB) and stearyltrimethylammonium bromide (STAB), and the organification of MMT was proved by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron micrographic (SEM) and transmission electron microscope (TEM). The adsorption of Congo Red (CR) anionic dye from aqueous solution onto surfactant-modified MMT was carried out. Compared with MMT, the adsorption capacity of surfactant-modified MMT for CR was greatly enhanced and MMT modified with CTAB (2.0 CEC) exhibited the higher adsorption capacity. The effects of pH value of the dye solution, adsorption temperature, adsorption time and the initial dye concentration on the adsorption capacity of CR on CTAB-MMT have been investigated. The results showed that the adsorption kinetic of CR on CTAB-MMT could be best described by the pseudo-second-order model and that the adsorption isotherm of CR was in good agreement with the Langmuir equation. The IR spectra and SEM analysis also revealed that the adsorption of CTAB-MMT was a chemical adsorption process between CTAB and the NH 2 , -N=N- and SO 3 groups of CR

Enhancing Nitrogen Availability, Ammonium Adsorption-Desorption, and Soil pH Buffering Capacity using Composted Paddy Husk

Science.gov (United States)

Latifah, O.; Ahmed, O. H.; Abdul Majid, N. M.

2017-12-01

Form of nitrogen present in soils is one of the factors that affect nitrogen loss. Nitrate is mobile in soils because it does not absorb on soil colloids, thus, causing it to be leached by rainfall to deeper soil layers or into the ground water. On the other hand, temporary retention and timely release of ammonium in soils regulate nitrogen availability for crops. In this study, composted paddy husk was used in studies of soil leaching, buffering capacity, and ammonium adsorption and desorption to determine the: (i) availability of exchangeable ammonium, available nitrate, and total nitrogen in an acid soil after leaching the soil for 30 days, (ii) soil buffering capacity, and (iii) ability of the composted paddy husk to adsorb and desorb ammonium from urea. Leaching of ammonium and nitrate were lower in all treatments with urea and composted paddy husk compared with urea alone. Higher retention of soil exchangeable ammonium, available nitrate, and total nitrogen of the soils with composted paddy husk were due to the high buffering capacity and cation exchange capacity of the amendment to adsorb ammonium thus, improving nitrogen availability through temporary retention on the exchange sites of the humic acids of the composted paddy husk. Nitrogen availability can be enhanced if urea is amended with composted paddy husk.

Effect of agitation speed on adsorption of imidacloprid on activated carbon

International Nuclear Information System (INIS)

Zahoor, M.

2011-01-01

The adsorptive characteristics of imidacloprid on powdered activated carbon were described. The adsorption experiments were carried out as function of time, initial concentration and agitation speed. The equilibrium data fits well to Langmuir adsorption isotherm, while the kinetic data fits well to Pseudo second order kinetic model. The kinetic experiments were carried out at 200, 250, 300 and 350 rpm and it was found that the equilibrium time increases with increase in initial concentration and decreases with increase in agitation speed. This is due to the increased turbulence and as a consequence, the decrease boundary layer thickness around the adsorbent particles as a result of increasing the degree of mixing. At 300 rpm the adsorption capacity was maximum and beyond this there was no significant increase in adsorption capacity. Weber intra particle diffusion model was used to describe the adsorption mechanism. It was found that both the boundary layer and intra particle diffusion for both adsorbents played important role in the adsorption mechanisms of the adsorbate. The effects of temperature and pH on adsorption were also studied. It was found that the adsorption capacity of the adsorbent decreases with increase in temperature. There was no significant change in adsorption from pH 2 to 8, however at high pH a decrease in adsorption of imidacloprid on activated carbon was observed. (author)

Removal of mercury from coal-combustion flue gas using regenerable sorbents

Energy Technology Data Exchange (ETDEWEB)

Turchi, C S; Albiston, J; Broderick, T E; Stewart, R M

1999-07-01

The US EPA estimates that coal-fired power plants constitute the largest anthropogenic source of mercury emissions in the US. The Agency has contemplated emission regulations for power plants, but the large gas-flow rates and low mercury concentrations involved have made current treatment options prohibitively expensive. ADA Technologies, Inc. (Englewood, Colorado), in conjunction with the US DOE, is developing regenerable sorbents for the removal and recovery of mercury from flue gas. These sorbents are based on the ability of noble metals to amalgamate mercury at typical flue-gas temperatures and release mercury at higher temperatures. The process allows for recovery of mercury with minimal volumes of secondary wastes and no impact on fly ash quality. In 1997 and 1998, ADA tested a 20-cfm sorbent unit at CONSOL Inc.'s coal-combustion test facility in Library, PA. Results from the 1997 tests indicated that the sorbent can remove elemental and oxidized mercury and can be regenerated without loss of capacity. Design changes were implemented in 1998 to enhance the thermal efficiency of the process and to recover the mercury in a stable form. Testing during autumn, 1998 demonstrated 60% to 90% removal efficiency of mercury from a variety of different coals. However, contradictory removal results were obtained at the end of the test period. Subsequent laboratory analyses indicated that the sorbent had lost over half its capacity for mercury due to a decrease in available sites for mercury sorption. The presence of sulfur compounds on the sorbent suggests that thermal cycling may have condensed acid gases on the sorbent leading to deterioration of the active sorption sites. The regeneration time/temperature profile has been altered to minimize this potential in the upcoming power plant tests.

Adsorption of emerging contaminant metformin using graphene oxide.

Science.gov (United States)

Zhu, Shuai; Liu, Yun-Guo; Liu, Shao-Bo; Zeng, Guang-Ming; Jiang, Lu-Hua; Tan, Xiao-Fei; Zhou, Lu; Zeng, Wei; Li, Ting-Ting; Yang, Chun-Ping

2017-07-01

The occurrence of emerging contaminants in our water resources poses potential threats to the livings. Due to the poor treatment in wastewater management, treatment technologies are needed to effectively remove these products for living organism safety. In this study, Graphene oxide (GO) was tested for the first time for its capacity to remove a kind of emerging wastewater contaminants, metformin. The research was conducted by using a series of systematic adsorption and kinetic experiments. The results indicated that GO could rapidly and efficiently reduce the concentration of metformin, which could provide a solution in handling this problem. The uptake of metformin on the graphene oxide was strongly dependent on temperature, pH, ionic strength, and background electrolyte. The adsorption kinetic experiments revealed that almost 80% removal of metformin was achieved within 20 min for all the doses studied, corresponding to the relatively high k 1 (0.232 min -1 ) and k 2 (0.007 g mg -1  min -1 ) values in the kinetic models. It indicated that the highest adsorption capacity in the investigated range (q m ) of GO for metformin was at pH 6.0 and 288 K. Thermodynamic study indicated that the adsorption was a spontaneous (ΔG 0  adsorption of metformin increased when the pH values changed from 4.0 to 6.0, and decreased adsorption were observed at pH 6.0-11.0. GO still exhibited excellent adsorption capacity after several desorption/adsorption cycles. Besides, both so-called π-π interactions and hydrogen bonds might be mainly responsible for the adsorption of metformin onto GO. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effect of heat treatment on CO2 adsorption of KOH-activated graphite nanofibers.

Science.gov (United States)

Meng, Long-Yue; Park, Soo-Jin

2010-12-15

In this work, graphite nanofibers (GNFs) were successfully expanded intercalating KOH followed by heat treatment in the temperature range of 700-1000 °C. The aim was to improve the CO(2) adsorption capacity of the GNFs by increasing the porosity of GNFs. The effects of heat treatment on the pore structures of GNFs were investigated by N(2) full isotherms, XRD, SEM, and TEM. The CO(2) adsorption capacity was measured by CO(2) isothermal adsorption at 25 °C and 1 atm. From the results, it was found that the activation temperature had a major influence on CO(2) adsorption capacity and textural properties of GNFs. The specific surface area, total pore volume, and mesopore volume of the GNFs increased after heat treatment. The CO(2) adsorption isotherms showed that G-900 exhibited the best CO(2) adsorption capacity with 59.2 mg/g. Copyright © 2010 Elsevier Inc. All rights reserved.

Effect of some pre-treatments on the adsorption of methylene blue by Balkaya lignite

International Nuclear Information System (INIS)

Karaca, S.; Guerses, A.; Bayrak, R.

2004-01-01

In this study, the effects of some pre-treatments, such as HCl treatment, demineralization and pyrolysis, under a CO 2 atmosphere at different temperatures on the adsorption of methylene blue by Balkaya lignite were investigated. The adsorption capacities of the samples were determined before and after these pre-treatments. In addition, the removals of pyritic and organic sulfur and ash contents for the same coal samples were also defined. It was found that the adsorption capacities of the samples decreased after these pre-treatments. The decrease in adsorption capacity with pyrolysis can be attributed to the changes in surface morphology and/or pore size distribution of the coal samples. On the other hand, the observed decrease in adsorption capacity with removal of carbonates and silicates shows that these minerals have an important effect on methylene blue adsorption, and the adsorption considerably occurs through electrostatic interactions. In addition, the obtained results showed that the organic sulfur presence in the coal matrix have a positive effect on the methylene blue adsorption

Experimental study on removals of SO2 and NOX using adsorption of activated carbon/microwave desorption.

Science.gov (United States)

Ma, Shuang-Chen; Yao, Juan-Juan; Gao, Li; Ma, Xiao-Ying; Zhao, Yi

2012-09-01

Experimental studies on desulfurization and denitrification were carried out using activated carbon irradiated by microwave. The influences of the concentrations of nitric oxide (NO) and sulfur dioxide (SO 2 ), the flue gas coexisting compositions, on adsorption properties of activated carbon and efficiencies of desulfurization and denitrification were investigated. The results show that adsorption capacity and removal efficiency of NO decrease with the increasing of SO 2 concentrations in flue gas; adsorption capacity of NO increases slightly first and drops to 12.79 mg/g, and desulfurization efficiency descends with the increasing SO 2 concentrations. Adsorption capacity of SO 2 declines with the increasing of O 2 content in flue gas, but adsorption capacity of NO increases, and removal efficiencies of NO and SO 2 could be larger than 99%. Adsorption capacity of NO declines with the increase of moisture in the flue gas, but adsorption capacity of SO 2 increases and removal efficiencies of NO and SO 2 would be relatively stable. Adsorption capacities of both NO and SO 2 decrease with the increasing of CO 2 content; efficiencies of desulfurization and denitrification augment at the beginning stage, then start to fall when CO 2 content exceeds 12.4%. The mechanisms of this process are also discussed. [Box: see text].

Impact of salinity and dispersed oil on adsorption of dissolved aromatic hydrocarbons by activated carbon and organoclay

Energy Technology Data Exchange (ETDEWEB)

Younker, Jessica M.; Walsh, Margaret E., E-mail: mwalsh2@dal.ca

2015-12-15

Highlights: • Powdered activated carbon (PAC) outperformed organoclay for dissolved aromatics removal • Dispersed oil reduced the adsorption capacity of PAC but not organoclay • Salinity did not affect phenol or naphthalene removal by PAC or BTMA-organoclay • Commercial organoclay had reduced adsorption capacity in saline water due to aggregation • PAC performed better in single solute systems than multi-solute systems - Abstract: Adsorption capacity of phenol and naphthalene by powdered activated carbon (PAC), a commercial organoclay (OC) and a lab synthesized organoclay (BTMA) was studied using batch adsorption experiments under variable feed water quality conditions including single- and multi- solute conditions, fresh water, saline water and oily-and-saline water. Increasing salinity levels was found to reduce adsorption capacity of OC, likely due to destabilization, aggregation and subsequent removal of organoclay from the water column, but did not negatively impact adsorption capacity of PAC or BTMA. Increased dispersed oil concentrations were found to reduce the surface area of all adsorbents. This decreased the adsorption capacity of PAC for both phenol and naphthalene, and reduced BTMA adsorption of phenol, but did not negatively affect naphthalene removals by either organoclay. The presence of naphthalene as a co-solute significantly reduced phenol adsorption by PAC, but had no impact on organoclay adsorption. These results indicated that adsorption by PAC occurred via a surface adsorption mechanism, while organoclay adsorption occurred by hydrophobic or pi electron interactions. In general, PAC was more sensitive to changes in water quality than either of the organoclays evaluated in this study. However, PAC exhibited a higher adsorption capacity for phenol and naphthalene compared to both organoclays even in adverse water quality conditions.

Impact of salinity and dispersed oil on adsorption of dissolved aromatic hydrocarbons by activated carbon and organoclay

International Nuclear Information System (INIS)

Younker, Jessica M.; Walsh, Margaret E.

2015-01-01

Highlights: • Powdered activated carbon (PAC) outperformed organoclay for dissolved aromatics removal • Dispersed oil reduced the adsorption capacity of PAC but not organoclay • Salinity did not affect phenol or naphthalene removal by PAC or BTMA-organoclay • Commercial organoclay had reduced adsorption capacity in saline water due to aggregation • PAC performed better in single solute systems than multi-solute systems - Abstract: Adsorption capacity of phenol and naphthalene by powdered activated carbon (PAC), a commercial organoclay (OC) and a lab synthesized organoclay (BTMA) was studied using batch adsorption experiments under variable feed water quality conditions including single- and multi- solute conditions, fresh water, saline water and oily-and-saline water. Increasing salinity levels was found to reduce adsorption capacity of OC, likely due to destabilization, aggregation and subsequent removal of organoclay from the water column, but did not negatively impact adsorption capacity of PAC or BTMA. Increased dispersed oil concentrations were found to reduce the surface area of all adsorbents. This decreased the adsorption capacity of PAC for both phenol and naphthalene, and reduced BTMA adsorption of phenol, but did not negatively affect naphthalene removals by either organoclay. The presence of naphthalene as a co-solute significantly reduced phenol adsorption by PAC, but had no impact on organoclay adsorption. These results indicated that adsorption by PAC occurred via a surface adsorption mechanism, while organoclay adsorption occurred by hydrophobic or pi electron interactions. In general, PAC was more sensitive to changes in water quality than either of the organoclays evaluated in this study. However, PAC exhibited a higher adsorption capacity for phenol and naphthalene compared to both organoclays even in adverse water quality conditions.

Effect of the surface oxygen groups on methane adsorption on coals

Energy Technology Data Exchange (ETDEWEB)

Hao Shixiong [Department of Chemical Engineering, Sichuan University, Chengdu 610065 (China); Department of Chemical Engineering, Sichuan University of Science and Engineering, Zigong 643000 (China); Wen Jie [Department of Chemical Engineering, Sichuan University, Chengdu 610065 (China); Yu Xiaopeng [Department of Chemical Engineering, Sichuan University, Chengdu 610065 (China); Department of Chemical Engineering, Sichuan University of Science and Engineering, Zigong 643000 (China); Chu Wei, E-mail: chuwei1965_scu@yahoo.com [Department of Chemical Engineering, Sichuan University, Chengdu 610065 (China)

2013-01-01

Highlights: Black-Right-Pointing-Pointer We modified one coal with H{sub 2}O{sub 2}, (NH{sub 4}){sub 2}S{sub 2}O{sub 8} and HNO{sub 3} respectively, to prepare coal samples with different surface properties. Black-Right-Pointing-Pointer The oxygen groups on coal surface were characterized by XPS. Black-Right-Pointing-Pointer The textures of the coal samples were investigated by N{sub 2} adsorption at 77 K. Black-Right-Pointing-Pointer The adsorption behaviors were measured by volumetric method. Black-Right-Pointing-Pointer There was a negative correlation between methane saturated adsorption capacity and the O{sub total}/C{sub total}. - Abstract: To investigate the influence of surface oxygen groups on methane adsorption on coals, one bituminous coal was modified with H{sub 2}O{sub 2}, (NH{sub 4}){sub 2}S{sub 2}O{sub 8} and HNO{sub 3} respectively, to prepare coal samples with different surface properties. The oxygen groups on coal surface were characterized by X-ray photoelectron spectroscopy (XPS). The textures of the coal samples were investigated by N{sub 2} adsorption at 77 K. Their surface morphologies were analyzed by scanning electron microscopy (SEM). The methane adsorption behaviors of these coal samples were measured at 303 K in pressure range of 0-5.3 MPa by volumetric method. The adsorption data of methane were fitted to the Langmuir model and Dubinin-Astakhov (D-A) model. The fitting results showed that the D-A model fitted the isotherm data better than the Langmuir model. It was observed that there was, in general, a positive correlation between the methane saturated adsorption capacity and the micropore volume of coals while a negative correlation between methane saturated adsorption capacity and the O{sub total}/C{sub total}. The methane adsorption capacity was determined by the coal surface chemistry when the microporosity parameters of two samples were similar. Coal with a higher amount of oxygen surface groups, and consequently with a less

Characterization of trichloroethylene adsorption onto waste biocover soil in the presence of landfill gas.

Science.gov (United States)

He, Ruo; Su, Yao; Kong, Jiaoyan

2015-09-15

Waste biocover soils (WBS) have been demonstrated to have great potential in mitigating trichloroethylene (TCE) emission from landfills, due to the relatively high TCE-degrading capacity. In this study, the characteristics of TCE adsorption on WBS in the presence of the major landfill gas components (i.e., CH4 and CO2) were investigated in soil microcosms. The adsorption isotherm of TCE onto WBS was fitted well with linear model within the TCE concentrations of 7000 ppmv. The adsorption capacity of TCE onto WBS was affected by temperature, soil moisture content and particle size, of which, temperature was the dominant factor. The adsorption capacity of TCE onto the experimental materials increased with the increasing organic matter content. A significantly positive correlation was observed between the adsorption capacity of TCE and the organic matter content of experimental materials that had relatively higher organic content (r = 0.988, P = 0.044). To better understand WBS application in practice, response surface methodology was developed to predict TCE adsorption capacity and emissions through WBS in different landfills in China. These results indicated that WBS had high adsorption capacity of TCE in LFG and temperature should be paid more attention to manipulate WBS to reduce TCE emissions from landfills. Copyright © 2015 Elsevier B.V. All rights reserved.

Fluorocarbon adsorption in hierarchical porous frameworks

Energy Technology Data Exchange (ETDEWEB)

Motkuri, RK; Annapureddy, HVR; Vijaykumar, M; Schaef, HT; Martin, PF; McGrail, BP; Dang, LX; Krishna, R; Thallapally, PK

2014-07-09

Metal-organic frameworks comprise an important class of solid-state materials and have potential for many emerging applications such as energy storage, separation, catalysis and bio-medical. Here we report the adsorption behaviour of a series of fluorocarbon derivatives on a set of microporous and hierarchical mesoporous frameworks. The microporous frameworks show a saturation uptake capacity for dichlorodifluoromethane of >4 mmol g(-1) at a very low relative saturation pressure (P/P-o) of 0.02. In contrast, the mesoporous framework shows an exceptionally high uptake capacity reaching >14 mmol g(-1) at P/P-o of 0.4. Adsorption affinity in terms of mass loading and isosteric heats of adsorption is found to generally correlate with the polarizability and boiling point of the refrigerant, with dichlorodifluoromethane >chlorodifluoromethane >chlorotrifluoromethane >tetrafluoromethane >methane. These results suggest the possibility of exploiting these sorbents for separation of azeotropic mixtures of fluorocarbons and use in eco-friendly fluorocarbon-based adsorption cooling.

Mechanism of amitriptyline adsorption on Ca-montmorillonite (SAz-2)

Energy Technology Data Exchange (ETDEWEB)

Chang, Po-Hsiang [Department of Earth Sciences, National Cheng Kung University, 1 University Road, Tainan 70101, Taiwan (China); Jiang, Wei-Teh, E-mail: atwtj@mail.ncku.edu.tw [Department of Earth Sciences, National Cheng Kung University, 1 University Road, Tainan 70101, Taiwan (China); Li, Zhaohui, E-mail: li@uwp.edu [Department of Geosciences, University of Wisconsin – Parkside, 900 Wood Road, Kenosha, WI 53144 (United States); Kuo, Chung-Yih [Department of Public Health, College of Health Care and Management, Chung Shan Medical University, No. 110, Sec. 1, Chien-kuo N Road, Taichung 40242, Taiwan (China); Jean, Jiin-Shuh [Department of Earth Sciences, National Cheng Kung University, 1 University Road, Tainan 70101, Taiwan (China); Chen, Wan-Ru [Department of Environmental Engineering, National Cheng Kung University, 1 University Road, Tainan 70101, Taiwan (China); Lv, Guocheng [School of Materials Science and Technology, China University of Geosciences, Beijing 100083 (China)

2014-07-30

Graphical abstract: XRD patterns to show AMI intercalation into SAz-2 vs. direct mixing of the same amount of AMI with SAz-2. - Highlights: • Ca-montmorillonite is proven to be an efficient adsorbent or sink for amitriptyline. • The high adsorption capacity is accompanied with intercalation into interlayers. • The adsorption is mainly governed by a cation exchange mechanism. • Horizontal mono- and bi-layer conformations occur at low and high adsorption levels. • The process is an endothermic physisorption at high adsorption levels. - Abstract: The uptake of amitriptyline (AMI) from aqueous environment by Ca-montmorillonite (SAz-2) was studied in a batch system under different physicochemical conditions. The adsorbent was characterized by X-ray diffraction and Fourier transform infrared (FTIR) analyses. The AMI adsorption on SAz-2 obeyed the Langmuir isotherm with a capacity of 330 mg/g (1.05 mmol/g) at pH 6–7. The adsorption kinetics was fast, almost reaching equilibrium in 2 h, and followed a pseudo-second-order kinetic model. Desorption of exchangeable cations correlated with the AMI adsorption well, indicating that cation exchange was the major mechanism. X-ray diffraction patterns showing significant expansions of the d{sub 0} {sub 0} {sub 1} spacing and characteristic FTIR band shifts toward higher frequencies after AMI adsorption onto SAz-2 indicated that the adsorbed AMI molecules were intercalated into the interlayers of the mineral. Thermodynamic parameters based on partitioning coefficients suggested that the AMI adsorption was an endothermic physisorption at high adsorption levels. At low and higher AMI adsorption levels, the intercalated AMI molecules take a horizontal monolayer and bilayer conformation, respectively. The higher adsorption capacity suggested that SAz-2 could be a good candidate to remove AMI from wastewater and would be an important environmental sink for the fate and transport of AMI in soils and groundwater.

Mechanism of amitriptyline adsorption on Ca-montmorillonite (SAz-2)

International Nuclear Information System (INIS)

Chang, Po-Hsiang; Jiang, Wei-Teh; Li, Zhaohui; Kuo, Chung-Yih; Jean, Jiin-Shuh; Chen, Wan-Ru; Lv, Guocheng

2014-01-01

Graphical abstract: XRD patterns to show AMI intercalation into SAz-2 vs. direct mixing of the same amount of AMI with SAz-2. - Highlights: • Ca-montmorillonite is proven to be an efficient adsorbent or sink for amitriptyline. • The high adsorption capacity is accompanied with intercalation into interlayers. • The adsorption is mainly governed by a cation exchange mechanism. • Horizontal mono- and bi-layer conformations occur at low and high adsorption levels. • The process is an endothermic physisorption at high adsorption levels. - Abstract: The uptake of amitriptyline (AMI) from aqueous environment by Ca-montmorillonite (SAz-2) was studied in a batch system under different physicochemical conditions. The adsorbent was characterized by X-ray diffraction and Fourier transform infrared (FTIR) analyses. The AMI adsorption on SAz-2 obeyed the Langmuir isotherm with a capacity of 330 mg/g (1.05 mmol/g) at pH 6–7. The adsorption kinetics was fast, almost reaching equilibrium in 2 h, and followed a pseudo-second-order kinetic model. Desorption of exchangeable cations correlated with the AMI adsorption well, indicating that cation exchange was the major mechanism. X-ray diffraction patterns showing significant expansions of the d 0 0 1 spacing and characteristic FTIR band shifts toward higher frequencies after AMI adsorption onto SAz-2 indicated that the adsorbed AMI molecules were intercalated into the interlayers of the mineral. Thermodynamic parameters based on partitioning coefficients suggested that the AMI adsorption was an endothermic physisorption at high adsorption levels. At low and higher AMI adsorption levels, the intercalated AMI molecules take a horizontal monolayer and bilayer conformation, respectively. The higher adsorption capacity suggested that SAz-2 could be a good candidate to remove AMI from wastewater and would be an important environmental sink for the fate and transport of AMI in soils and groundwater

Assessing The Impact Of Mercury Contamination To Lake Balkyldak In Kazakhstan

Science.gov (United States)

Adjacent to Lake Balkyldak in Kazakhstan, there is a large wastewater holding pond from a former mercury cell chloralkali plant which contains high levels of mercury-contamination. The holding pond capacity is 74 million m3 with a water-surface area of 18 km2

Highly Productive Synthesis, Characterization, and Fluorescence and Heavy Metal Ion Adsorption Properties of Poly(2,5-dimercapto-1,3,4-thiadiazole Nanosheets

Directory of Open Access Journals (Sweden)

Chao Li

2017-12-01

Full Text Available Poly(2,5-dimercapto-1,3,4-thiadiazole (PBT nanosheets were synthesized by chemical oxidative synthesis under mild conditions. The media, oxidant species, monomer concentrations, oxidant/monomer molar ratio, and temperature were optimized to achieve higher yields and better performance. The molecular structure, morphology, and properties of the nanosheets were analyzed by Fourier transform infrared (FT-IR, ultraviolet-visible (UV-Vis, and fluorescence spectroscopies, wide-angle X-ray diffraction (WAXD, matrix-assisted laser desorption/ionization/time-of-flight (MALDI-TOF mass spectrometry, X-ray photoelectron spectroscopy (XPS, scanning electronic microscopy (SEM, transmission electron microscopy (TEM, and simultaneous thermogravimetry and differential scanning calorimetry (TG-DSC. It was found that the polymerization of 2,5-dimercapto-1,3,4-thiadiazole occurs via dehydrogenation coupling between two mercapto groups to form the –S–S– bond. PBTs show the highest polymerization yield of up to 98.47% and form uniform nanosheets with a thickness of 89~367 nm. poly(2,5-dimercapto-1,3,4-thiadiazole polymers (PBTs exhibit good chemical resistance, high thermostability, interesting blue-light emitting fluorescence, and wonderful heavy metal ion adsorption properties. Particularly, the PBT nanosheets having a unique synergic combination of three kinds of active –S–, –SH, and =N– groups with a moderate specific area of 15.85 m2 g−1 exhibit an ultra-rapid initial adsorption rate of 10,653 mg g−1 h−1 and an ultrahigh adsorption capacity of up to 680.01 mg g−1 for mercury ion, becoming ultrafast chelate nanosorbents with a high adsorption capacity. With these impressive properties, PBT nanosheets are very promising materials in the fields of water treatment, sensors, and electrodes.

ADSORPTION OF PITCH AND STICKIES ON MAGNESIUM ALUMINUM HYDROXIDES TREATED AT DIFFERENT TEMPERAURES

Directory of Open Access Journals (Sweden)

Guodong Li

2011-04-01

Full Text Available Magnesium aluminum hydroxides (MAH of nitrate and carbonate forms were prepared by co-precipitation, dried at different temperatures, and employed as an adsorbent for pitch and stickies in papermaking. Results indicated that MAH that had been heat-treated had higher adsorption capacity to model pitch and stickies at neutral pH. Low-temperature-dried magnesium aluminum hydroxides of nitrate form (MAH-NO3 had higher adsorption capacity to model pitch and model stickies than those of the carbonate form (MAH-CO3. Increasing the drying temperature of MAH reduced the difference of adsorption capacity between MAH-NO3 and MAH-CO3. Higher-temperature-dried magnesium aluminum hydroxides also showed higher adsorption capacity to model pitch and stickies when the drying temperature was lower than 550 oC. MAH displayed higher adsorption capacity while a lower initial adsorption rate of model stickies than of model pitch. The model pitch and stickies were adsorbed on MAH significantly by charge neutralization and distributed mainly on the surface of the platelets of magnesium aluminum hydroxides. The experimental isothermal adsorption data of model pitch and stickies on MAH dried at 500 oC fit well to the Freundlich and Dubinin–Radushkevich isotherm equations.

Adsorption of palladium ions by modified carbons from rice husks

International Nuclear Information System (INIS)

Mostafa, M.R.

1994-01-01

Steam activated carbon of high surface area does not show palladium ions adsorption. Treatment of this carbon with HF acid increases to a great extent the gas adsorption capacity expressed as nitrogen surface area as well as the adsorption capacity of palladium ions from aqueous solution. HHB was loaded in different amounts on to these carbons. The acid sites represent the active fraction of the surface on which the adsorption palladium ions proceed. The uptake of palladium ions by HHB treated carbons is related to the total number of HHB molecules loaded on the carbon surface. (author)

Adsorption of phenol on metal treated by granular activated carbon

International Nuclear Information System (INIS)

Kang, Kwang Cheol; Kwon, Soo Han; Kim, Seung Soo; Baik, Min Hoon; Choi, Jong Won; Kim, Jin Won

2007-01-01

In this study, the effect of metal treatment on Granular Activated Carbon (GAC) was investigated in the context of phenol adsorption. Cobalt(II) nitrate, and zinc(II) nitrate solution were used for metal treated. The specific surface area and the pore structure were evaluated from nitrogen adsorption data at 77 K. The phenol adsorption rates onto GAC were measured by UV-Vis spectrophotometer. Iodine adsorption capacity of Co-GAC is much better then that of the GAC. The Co-GAC with mesopore is more efficient than other adsorbents for the adsorption of polymer such as methyleneblue. The adsorption capacity of reference-GAC and metal-GAC were increased in order of Co-GAC>Zn-GAC>Reference-GAC, in spite of a decrease in specific surface area which was resulted from pore blocking by metal

Zeolite Y Adsorbents with High Vapor Uptake Capacity and Robust Cycling Stability for Potential Applications in Advanced Adsorption Heat Pumps.

Science.gov (United States)

Li, Xiansen; Narayanan, Shankar; Michaelis, Vladimir K; Ong, Ta-Chung; Keeler, Eric G; Kim, Hyunho; McKay, Ian S; Griffin, Robert G; Wang, Evelyn N

2015-01-01

Modular and compact adsorption heat pumps (AHPs) promise an energy-efficient alternative to conventional vapor compression based heating, ventilation and air conditioning systems. A key element in the advancement of AHPs is the development of adsorbents with high uptake capacity, fast intracrystalline diffusivity and durable hydrothermal stability. Herein, the ion exchange of NaY zeolites with ingoing Mg 2+ ions is systematically studied to maximize the ion exchange degree (IED) for improved sorption performance. It is found that beyond an ion exchange threshold of 64.1%, deeper ion exchange does not benefit water uptake capacity or characteristic adsorption energy, but does enhance the vapor diffusivity. In addition to using water as an adsorbate, the uptake properties of Mg,Na-Y zeolites were investigated using 20 wt.% MeOH aqueous solution as a novel anti-freeze adsorbate, revealing that the MeOH additive has an insignificant influence on the overall sorption performance. We also demonstrated that the labscale synthetic scalability is robust, and that the tailored zeolites scarcely suffer from hydrothermal stability even after successive 108-fold adsorption/desorption cycles. The samples were analyzed using N 2 sorption, 27 Al/ 29 Si MAS NMR spectroscopy, ICP-AES, dynamic vapor sorption, SEM, Fick's 2 nd law and D-R equation regressions. Among these, close examination of sorption isotherms for H 2 O and N 2 adsorbates allows us to decouple and extract some insightful information underlying the complex water uptake phenomena. This work shows the promising performance of our modified zeolites that can be integrated into various AHP designs for buildings, electronics, and transportation applications.

Kinetic studies of uranyl ion adsorption on acrylonitrile (AN) / polyethylene glycol (PEG) interpenetrating networks (IPN)

International Nuclear Information System (INIS)

Aycik, G.A.; Gurellier, R.

2004-01-01

The kinetics of the adsorption of uranyl ions on amidoximated acrylonitrile (AN)/ polyethylene glycol (PEG) interpenetrating network (IPNs) from aqueous solutions was studied as a function of time and temperature. Adsorption analyses were performed for definite uranyl ion concentrations of 1x10 -2 M and at four different temperatures as 290K, 298K, 308K and 318K. Adsorption time was increased from zero to 48 hours. Adsorption capacities of uranyl ions by PEG/AN IPNS were determined by gamma spectrometer. The results indicate that adsorption capacity increases linearly with increasing temperature. The max adsorption capacity was found as 602 mgu/g IPN at 308K. Adsorption rate was evaluated from the curve plotted of adsorption capacity versus time, for each temperature. Rate constants for uranyl ions adsorption on amidoximated ipns were calculated for 290K, 298K, 308K and 318K at the solution concentration of 1x10 -2 M . The results showed that as the temperature increases the rate constant increases exponentially too. The mean activation energy of uranyl ions adsorption was found as 34.6 kJ/mole by using arrhenius equation. (author)

[Adsorption and removal of gas-phase Hg(0) over a V2O5/AC catalyst in the presence of SO2].

Science.gov (United States)

Wang, Jun-wei; Yang, Jian-li; Liu, Zhen-yu

2009-12-01

The adsorption and removal behaviors of gas-phase Hg(0) over V2O5/AC and AC were studied under a simulated flue gas (containing N2, SO2, O2) in a fixed-bed reactor. The influences of the V2O5, loading, SO2 concentration and adsorption temperature on Hg0 adsorption were investigated. The speciation of mercury adsorbed was determined by X-ray photoelectron spectroscopy (XPS). It was found that the V2O5/AC catalyst has a much higher capability than AC for Hg(0) adsorption and removal, mainly because of the catalytic oxidation activity of V2O5. The Hg(0) adsorption capability depends on the V2O5 content of the V2O5/AC catalyst. The amounts of mercury adsorbed increase from 75.9 microg x g(-1) to 89.6 microg x g(-1) (in the absence of O2) and from 115.9 microg x g(-1) to 185.5 microg x g(-1) (in the presence of O2) as the V2O5 loading increases from 0.5% to 1.0%, which are much higher than those over AC under the same conditions (9.6 microg x g(-1) and 23.3 microg x g(-1)). SO2 in the flue gas enhances Hg(0) adsorption over the V2O5/AC catalyst, which is due to the reaction of SO2 and Hg(0) on V2O3/AC. But as the SO2 concentration increases from 500 x 10(-6) to 2000 x 10(-6), the amount of mercury adsorbed has only a slight increase. The optimal temperature for Hg(0) adsorption over the V2O5/AC catalyst is around 150 degrees C, at which the amounts of mercury adsorbed are up to 98.5 microg x g(-1) (in the absence of O2) and 187.7 microg x g(-1) (in the presence of O2). The XPS results indicate the formation of Hg(0) and HgSO4 on the surface of the V2O5/AC catalyst, which confirms the role of V2O5 and SO2.

Simultaneous adsorption of SO2 and NO from flue gas over mesoporous alumina.

Science.gov (United States)

Sun, Xin; Tang, Xiaolong; Yi, Honghong; Li, Kai; Ning, Ping; Huang, Bin; Wang, Fang; Yuan, Qin

2015-01-01

Mesoporous alumina (MA) with a higher ability to simultaneously remove SO2 and NO was prepared by the evaporation-induced self-assembly process. The adsorption capacities of MA are 1.79 and 0.702 mmol/g for SO2 and NO, respectively. The Brunauer-Emmett-Teller method was used to characterize the adsorbent. Simultaneous adsorption of SO2 and NO from flue gas over MA in different operating conditions had been studied in a fixed bed reactor. The effects of temperature, oxygen concentration and water vapour were investigated. The experimental results showed that the optimum temperature for MA to simultaneously remove SO2 and NO was 90°C. The simultaneous adsorption capacities of SO2 and NO could be enhanced by increasing O2 when its concentration was below 5%. The changes of simultaneous adsorption capacities were not obvious when O2 concentration was above 5%. The increase in relative humidity results in an increase after dropping of SO2 adsorption capacity, whereas the adsorption capacity of NO showed an opposite trend. The results suggest that MA is a great adsorbent for simultaneous removal of SO2 and NO from flue gas.

Improving the work environment in the fluorescent lamp recycling sector by optimizing mercury elimination.

Science.gov (United States)

Lecler, Marie-Thérèse; Zimmermann, François; Silvente, Eric; Masson, Alain; Morèle, Yves; Remy, Aurélie; Chollot, Alain

2018-02-26

One of the main issues in the fluorescent lamp recycling sector is the mercury contamination of output fractions and occupational exposure associated with recycling operations. The aim of this study is to carry out effective mercury mass balance determinations and improve mercury recovery by finding the optimal levels for the recycling process parameters. These optimizations will allow upstream mercury emissions to be reduced, which will help to avoid mercury exposure among WEEE recycling workers. Firstly, the distribution of mercury was assessed in new and spent lamps. For new fluorescent tubes, the mean percentage of mercury in the solid phase is lower in new fluorescent tubes (19.5% with 5.5% in glass, 9.7% in end caps and 4.3% in luminescent powder) than in spent tubes (33.3% with 8.3% in glass, 12.9% in end caps and 12.1% in luminescent powder). The parametric study also shows that the finer the grains of glass, the higher the concentration of mercury (1.2 µg Hg/g for glass size particle >1000 µm and 152.0 µg Hg/g for glass size particle recycling companies employ processes combining as heating and mixing techniques for the recovery of mercury from lamps in order to both (i) remove as much of the mercury as possible in vapor form and (ii) avoid adsorption of the mercury at new sites created during the crushing process. Copyright © 2018 Elsevier Ltd. All rights reserved.

SQUARE WAVE CATHODIC STRIPPING VOLTAMMETRY ADSORPTIVE FOR NICKEL AND COBALT ANALYSIS

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Saryati Saryati

2010-06-01

Full Text Available The adsorptive stripping voltammetric determination of Ni and Co based on adsorption of the Ni/Co and dimethylglioxime (DMG complex on a hanging mercury drop electrode is studied. The reduction current of the adsorbed DMG complex is measured by square wave cathodic stripping voltammetry method. The effect of various parameters such as ligand concentration, pH of supporting electrolytic, adsorption potential and adsorption time on the current peak of Ni and Co voltammogram were studied. Optimum condition of this method are supporting electrolyte pH 9, DMG concentration 5×10 -4 M, adsorption potential -0.7 V vs Ag/AgCl and adsorption time 180 second. A linier relationship between the current peak and Ni or Co concentration was obtained in the range 5 - 30 ng/mL and the detection limit 0.6 ng/ml for both Ni and Co. The recovery of Ni and Co were 98.11-104.17% using standard biological materials with RSD 2.59 - 10.37%. Based on ";t"; test can be conclude that the result are nearly equal to the standard reference material.   Keywords: adsorptive stripping voltammetric, dimethylglioxime complex, nickel, cobalt

Surfactant-free synthesis of octahedral ZnO/ZnFe2O4 heterostructure with ultrahigh and selective adsorption capacity of malachite green

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Liu, Jue; Zeng, Min; Yu, Ronghai

2016-05-01

A new octahedral ZnO/ZnFe2O4 heterostructure has been fabricated through a facile surfactant-free solvothermal method followed by thermal treatment. It exhibits a record-high adsorption capacity (up to 4983.0 mg·g-1) of malachite green (MG), which is a potentially harmful dye in prevalence and should be removed from wastewater and other aqueous solutions before discharging into the environment. The octahedral ZnO/ZnFe2O4 heterostructure also demonstrates strong selective adsorption towards MG from two kinds of mixed solutions: MG/methyl orange (MO) and MG/rhodamine B (RhB) mixtures, indicating its promise in water treatment.

Investigation of Mercury Reduction in Gold Stripping Process at Elevated Temperature

Science.gov (United States)

Pramudya, Irawan

Mercury is present in many gold ores. By processing these ores, there is a potential of emitting mercury to the environment. Carbon regeneration kiln stacks have been observed as one of the primary source of mercury emission into the atmosphere. Before it is recycled back into the carbon in leach (CIL) or carbon in columns (CIC), carbon used in the gold extraction process needs to be reactivated thermally. Emission of mercury can be minimized by keeping the mercury left in the carbon low before it goes to the carbon regeneration kiln stacks. The objective of this study is establishing the optimum elution conditions of mercury cyanide from loaded carbon (which includes the eluent, concentration, temperature and elution time) with respect to gold stripping. Several methods such as acid washing (UNR-100, HCl or ethanol/UNR-100) were investigated prior to the stripping process. Furthermore, conventional pressurized Zadra and modified Zadra were also studied with regards to mercury concentration in the solution and vapor state as well as maximizing the gold stripping from industrial loaded carbon. 7% UNR-100 acid washing of loaded carbon at 80°C was able to wash out approximately 90% of mercury while maintaining the gold adsorption on the carbon (selective washing). The addition of alcohol in the UNR-100 acid washing solution was able to enhance mercury washing from 90% to 97%. Furthermore, mercury stripping using conventional pressurized (cyanide-alkaline) Zadra was best performed at 80°C (minimal amount of mercury reduced and volatilized) whereas using the same process only 40% of gold was stripped, which makes this process not viable. When alcohol was added to the stripping solution, at 80°C, 95% of gold was detected in the solution while keeping the reduction and volatilization of mercury low. The outcome of this study provides a better understanding of mercury behavior during the acid washing and stripping processes so that the risk of mercury exposure and

Reactive adsorption of SO2 on activated carbons with deposited iron nanoparticles.

Science.gov (United States)

Arcibar-Orozco, Javier A; Rangel-Mendez, J Rene; Bandosz, Teresa J

2013-02-15

The effect of iron particle size anchored on the surface of commercial activated carbon on the removal of SO(2) from a gas phase was studied. Nanosize iron particles were deposited using forced hydrolysis of FeCl(3) with or without H(3)PO(4) as a capping agent. Dynamic adsorption experiments were carried out on either dry or pre-humidified materials and the adsorption capacities were calculated. The surface of the initial and exhausted materials was extensively characterized by microscopic, porosity, thermogravimetric and surface chemistry. The results indicate that the SO(2) adsorption capacity increased two and half times after the prehumidification process owing to the formation of H(2)SO(4) in the porous system. Iron species enhance the SO(2) adsorption capacity only when very small nanoparticles are deposited on the pore walls as a thin layer. Large iron nanoparticles block the ultramicropores decreasing the accessibility of the active sites and consuming oxygen that rest adsorption centers for SO(2) molecules. Iron nanoparticles of about 3-4 nm provide highly dispersed adsorption sites for SO(2) molecules and thus increase the adsorption capacity of about 80%. Fe(2)(SO(4))(3) was detected on the surface of exhausted samples. Copyright © 2012 Elsevier B.V. All rights reserved.

Phosphoryl functionalized mesoporous silica for uranium adsorption

International Nuclear Information System (INIS)

Xue, Guo; Yurun, Feng; Li, Ma; Dezhi, Gao; Jie, Jing; Jincheng, Yu; Haibin, Sun; Hongyu, Gong; Yujun, Zhang

2017-01-01

Highlights: • Phosphoryl functionalized mesoporous silica (TBP-SBA-15) is synthesized. • The amino and phosphoryl groups are successfully grafted on SBA-15. • TBP-SBA-15 has high and rapid uranium adsorption capacity in broad pH range. • The U(VI) adsorption of TBP-SBA-15 is spontaneous and belongs to chemical adsorption. - Abstract: Phosphoryl functionalized mesoporous silica (TBP-SBA-15) was synthesized by modified mesoporous silica with γ-amino propyl triethoxy silane and tributyl phosphate. The obtained samples were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), small angle X-ray diffraction (SAXRD), thermo-gravimetric/differential thermalanalyzer (TG/DTA), N_2 adsorption–desorption (BET) and Fourier transform infrared spectroscopy (FT-IR) techniques. Results showed that TBP-SBA-15 had large surface areas with ordered channel structure. Moreover, the effects of adsorption time, sorbent dose, solution pH, initial uranium concentration and temperature on the uranium adsorption behaviors were investigated. TBP-SBA-15 showed a high uranium adsorption capacity in a broad range of pH values. The U(VI) adsorption rate of TBP-SBA-15 was fast and nearly achieved completion in 10 min with the sorbent dose of 1 g/L. The U(VI) adsorption of TBP-SBA-15 followed the pseudo-second-order kinetic model and Freundlich isotherm model, indicating that the process was belonged to chemical adsorption. Furthermore, the thermodynamic parameters (ΔG"0, ΔH"0 and ΔS"0) confirmed that the adsorption process was endothermic and spontaneous.

Phosphoryl functionalized mesoporous silica for uranium adsorption

Energy Technology Data Exchange (ETDEWEB)

Xue, Guo; Yurun, Feng; Li, Ma; Dezhi, Gao; Jie, Jing; Jincheng, Yu; Haibin, Sun [Key Laboratory for Liquid-Solid Structural Evolution & Processing of Materials of Ministry of Education, Shandong University, Jinan 250061 (China); Key Laboratory of Special Functional Aggregated Materials, Ministry of Education, Shandong University, Jinan 250061 (China); Hongyu, Gong, E-mail: gong_hongyu@163.com [Key Laboratory for Liquid-Solid Structural Evolution & Processing of Materials of Ministry of Education, Shandong University, Jinan 250061 (China); Key Laboratory of Special Functional Aggregated Materials, Ministry of Education, Shandong University, Jinan 250061 (China); Yujun, Zhang, E-mail: yujunzhangcn@163.com [Key Laboratory for Liquid-Solid Structural Evolution & Processing of Materials of Ministry of Education, Shandong University, Jinan 250061 (China); Key Laboratory of Special Functional Aggregated Materials, Ministry of Education, Shandong University, Jinan 250061 (China)

2017-04-30

Highlights: • Phosphoryl functionalized mesoporous silica (TBP-SBA-15) is synthesized. • The amino and phosphoryl groups are successfully grafted on SBA-15. • TBP-SBA-15 has high and rapid uranium adsorption capacity in broad pH range. • The U(VI) adsorption of TBP-SBA-15 is spontaneous and belongs to chemical adsorption. - Abstract: Phosphoryl functionalized mesoporous silica (TBP-SBA-15) was synthesized by modified mesoporous silica with γ-amino propyl triethoxy silane and tributyl phosphate. The obtained samples were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), small angle X-ray diffraction (SAXRD), thermo-gravimetric/differential thermalanalyzer (TG/DTA), N{sub 2} adsorption–desorption (BET) and Fourier transform infrared spectroscopy (FT-IR) techniques. Results showed that TBP-SBA-15 had large surface areas with ordered channel structure. Moreover, the effects of adsorption time, sorbent dose, solution pH, initial uranium concentration and temperature on the uranium adsorption behaviors were investigated. TBP-SBA-15 showed a high uranium adsorption capacity in a broad range of pH values. The U(VI) adsorption rate of TBP-SBA-15 was fast and nearly achieved completion in 10 min with the sorbent dose of 1 g/L. The U(VI) adsorption of TBP-SBA-15 followed the pseudo-second-order kinetic model and Freundlich isotherm model, indicating that the process was belonged to chemical adsorption. Furthermore, the thermodynamic parameters (ΔG{sup 0}, ΔH{sup 0} and ΔS{sup 0}) confirmed that the adsorption process was endothermic and spontaneous.

The adsorption kinetics of metal ions onto different microalgae and siliceous earth.

Science.gov (United States)

Schmitt, D; Müller, A; Csögör, Z; Frimmel, F H; Posten, C

2001-03-01

In the present work the adsorption kinetics of the six metal ions aluminum, zinc, mercury, lead, copper, and cadmium onto living microalgae were measured. The freshwater green microalga Scenedesmus subspicatus, the brackish water diatom Cyclotella cryptica, the seawater diatom Phaeodactylum tricornutum, and the seawater red alga Porphyridium purpureum were the subject of investigation. In most cases the adsorption rate of the metals could be well described by using the equation of the Langmuir adsorption rate expression. Inverse parameter estimation allowed the determination of the rate constants of the adsorption process and the maximum metal content of the algae. The highest values for the rate constant were obtained for Porphyridium purpureum followed by Phaeodactylum tricornutum. High values for the maximum content were obtained for Cyclotella cryptica and Scenedesmus subspicatus. The maximum rate constant was 24.21 h-1 for the adsorption of Hg to Porphyridium purpureum whereas the maximum metal content (0.243 g g-1) was obtained for Zn on Cyclotella cryptica. A comparison of these values with those obtained for the mineral siliceous earth exhibiting low maximum content and high adsorption rates reveals that the mechanism of adsorption onto the algae is a mixture of adsorption and accumulation.

Optimal working pairs for solar adsorption cooling applications

International Nuclear Information System (INIS)

Allouhi, A.; Kousksou, T.; Jamil, A.; El Rhafiki, T.; Mourad, Y.; Zeraouli, Y.

2015-01-01

This article suggests a detailed comparison of 7 working pairs intended for use in solar adsorption cooling systems. The performance analysis was based on two indicators: adsorption capacity and solar coefficient of performance. Based on a reformed form of the Dubinin–Astakhov equation, a 3D graph was constructed to show the adsorbate concentration in the appropriate adsorbent as a first step to determine the adsorption capacity. A MATLAB program was developed to solve the system equation to predict the solar coefficient of performance for a typical summer day in a Moroccan city Fez. It was found that maximal adsorption capacity is obtained by activated carbon fibre/methanol (0.3406 kg kg −1 ) followed by activated carbon/methanol (0.2565 kg kg −1 ) and activated carbon/ethanol (0.2008 kg kg −1 ). At a condenser temperature of 25 °C, with an adsorbent mass of 20 kg, and an integrated collector-reactor configuration, the couple silica gel/water for air conditioning purpose can reach an SCOP of 0.3843. Activated carbon fibre/methanol is the following more efficient couple and can be used in the different cooling applications with an SCOP ranging from 0.1726 to 0.3287. Furthermore, adequate indicators are evaluated addressing the economic, environmental and safe aspects associated with each working pair. - Highlights: • 7 working pairs intended for use in solar adsorption cooling systems are compared. • A MATLAB program is used to predict the solar coefficient of performance. • Maximal adsorption capacity is obtained by activated carbon fibre/methanol

The Adsorption Mechanism of Modified Activated Carbon on Phenol

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Lin J. Q.

2016-01-01

Full Text Available Modified activated carbon was prepared by thermal treatment at high temperature under nitrogen flow. The surface properties of the activated carbon were characterized by Boehm titration, BET and point of zero charge determination. The adsorption mechanism of phenol on modified activated carbon was explained and the adsorption capacity of modified activated carbon for phenol when compared to plain activated carbon was evaluated through the analysis of adsorption isotherms, thermodynamic and kinetic properties. Results shows that after modification the surface alkaline property and pHpzc value of the activated carbon increase and the surface oxygen-containing functional groups decrease. The adsorption processes of the plain and modified carbon fit with Langmuir isotherm equation well, and the maximum adsorption capacity increase from 123.46, 111.11, 103.09mg/g to 192.31, 178.57, 163,93mg/g under 15, 25 and 35°C after modification, respectively. Thermodynamic parameters show that the adsorption of phenol on activated carbon is a spontaneously exothermic process of entropy reduction, implying that the adsorption is a physical adsorption. The adsorption of phenol on activated carbon follows the pseudo-second-order kinetics (R2>0.99. The optimum pH of adsorption is 6~8.

Adsorption of pharmaceuticals onto isolated polyamide active layer of NF/RO membranes.

Science.gov (United States)

Liu, Yan-Ling; Wang, Xiao-Mao; Yang, Hong-Wei; Xie, Yuefeng F

2018-06-01

Adsorption of trace organic compounds (TrOCs) onto the membrane materials has a great impact on their rejection by nanofiltration (NF) and reverse osmosis (RO) membranes. This study aimed to investigate the difference in adsorption of various pharmaceuticals (PhACs) onto different NF/RO membranes and to demonstrate the necessity of isolating the polyamide (PA) active layer from the polysulfone (PS) support layer for adsorption characterization and quantification. Both the isolated PA layers and the PA+PS layers of NF90 and ESPA1 membranes were used to conduct static adsorption tests. Results showed that apparent differences existed between the PA layer and the PA+PS layer in the adsorption capacity of PhACs as well as the time necessary to reach the adsorption equilibrium. PhACs with different physicochemical properties could be adsorbed to different extents by the isolated PA layer, which was mainly attributed to electrostatic attraction/repulsion and hydrophobic interactions. The PA layer of ESPA1 exhibited apparently higher adsorption capacities for the positively charged PhACs and similar adsorption capacities for the neutral PhACs although it had significantly less total interfacial area (per unit membrane surface area) for adsorption compared to the PA layer of NF90. The higher affinity of the PA layer of ESPA1 for the PhACs could be due to its higher capacity of forming hydrogen bonds with PhACs resulted from the modified chemistry with more -OH groups. This study provides a novel approach to determining the TrOC adsorption onto the active layer of membranes for the ease of investigating adsorption mechanisms. Copyright © 2018 Elsevier Ltd. All rights reserved.

Adsorption Characteristics of Different Adsorbents and Iron(III Salt for Removing As(V from Water

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Josip Ćurko

2016-01-01

Full Text Available The aim of this study is to determine the adsorption performance of three types of adsorbents for removal of As(V from water: Bayoxide® E33 (granular iron(III oxide, Titansorb® (granular titanium oxide and a suspension of precipitated iron(III hydroxide. Results of As(V adsorption stoichiometry of two commercial adsorbents and precipitated iron(III hydroxide in tap and demineralized water were fitted to Freundlich and Langmuir adsorption isotherm equations, from which adsorption constants and adsorption capacity were calculated. The separation factor RL for the three adsorbents ranged from 0.04 to 0.61, indicating effective adsorption. Precipitated iron(III hydroxide had the greatest, while Titansorb had the lowest capacity to adsorb As(V. Comparison of adsorption from tap or demineralized water showed that Bayoxide and precipitated iron(III hydroxide had higher adsorption capacity in demineralized water, whereas Titansorb showed a slightly higher capacity in tap water. These results provide mechanistic insights into how commonly used adsorbents remove As(V from water.

Arsenic Removal from Water by Adsorption on Iron-Contaminated Cryptocrystalline Graphite

Science.gov (United States)

Yang, Qiang; Yang, Lang; Song, Shaoxian; Xia, Ling

This work aimed to study the feasibility of using iron-contaminated graphite as an adsorbent for As(V) removal from water. The adsorbent was prepared by grinding graphite concentrate with steel ball. The study was performed through the measurements of adsorption capacity, BET surface area and XPS analysis. The experimental results showed that the iron-contaminated graphite exhibited significantly high adsorption capacity of As(V). The higher the iron contaminated on the graphite surface, the higher the adsorption capacity of As(V) on the material obtained. It was suggested that the ion-contaminated graphite was a good adsorbent for As(V) removal.

Mercury Removal From Aqueous Solutions With Chitosan-Coated Magnetite Nanoparticles Optimized Using the Box-Behnken Design

Science.gov (United States)

Rahbar, Nadereh; Jahangiri, Alireza; Boumi, Shahin; Khodayar, Mohammad Javad

2014-01-01

Background: Nowadays, removal of heavy metals from the environment is an important problem due to their toxicity. Objectives: In this study, a modified method was used to synthesize chitosan-coated magnetite nanoparticles (CCMN) to be used as a low cost and nontoxic adsorbent. CCMN was then employed to remove Hg2+ from water solutions. Materials and Methods: To remove the highest percentage of mercury ions, the Box-Behnken model of response surface methodology (RSM) was applied to simultaneously optimize all parameters affecting the adsorption process. Studied parameters of the process were pH (5-8), initial metal concentration (2-8 mg/L), and the amount of damped adsorbent (0.25-0.75 g). A second-order mathematical model was developed using regression analysis of experimental data obtained from 15 batch runs. Results: The optimal conditions predicted by the model were pH = 5, initial concentration of mercury ions = 6.2 mg/L, and the amount of damped adsorbent = 0.67 g. Confirmatory testing was performed and the maximum percentage of Hg2+ removed was found to be 99.91%. Kinetic studies of the adsorption process specified the efficiency of the pseudo second-order kinetic model. The adsorption isotherm was well-fitted to both the Langmuir and Freundlich models. Conclusions: CCMN as an excellent adsorbent could remove the mercury ions from water solutions at low and moderate concentrations, which is the usual amount found in environment. PMID:24872943

AUSTRALIAN PINE CONES-BASED ACTIVATED CARBON FOR ADSORPTION OF COPPER IN AQUEOUS SOLUTION

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MUSLIM A.

2017-02-01

Full Text Available The Australian Pine cones (APCs was utilised as adsorbent material by physical and chemical activation for the adsorption Cu(II in aqueous solution. FTIR and SEM analysis were conducted to obtain the active site and to characterise the surface morphology of the APCs activated carbon (APCs AC prepared through pyrolysis at 1073.15 K and alkaline activation of NaOH. The independent variables effect such as contact time, Cu(II initial concentration and the activator ratio in the ranges of 0-150 min, 84.88-370.21 mg/l and 0.2-0.6 (NaOH:APCs AC, respectively on the Cu(II adsorption capacity were investigated in the APCs activated carbon-solution (APCs ACS system with 1 g the APCs AC in 100 mL Cu(II aqueous solution with magnetic stirring at 75 rpm, room temperature of 298.15 K (± 2 K, 1 atm and pH 5 (±0.25. As the results, Cu(II adsorption capacity dramatically increased with increasing contact time and Cu(II initial concentration. The optimal Cu(II adsorption capacity of 26.71 mg/g was obtained in the APCs ACS system with 120-min contact time, 340.81 m/l initial Cu(II and 0.6 activator ratio. The kinetics study showed the Cu(II adsorption kinetics followed the pseudo-second-order kinetics with 27.03 mg/g of adsorption capacity, 0.09 g/mg.min of rate constant and 0.985-R2. In addition, the Cu(II adsorption isotherm followed the Langmuir model with 12.82 mg/g of the mono-layer adsorption capacity, 42.93 l/g of the over-all adsorption capacity and 0.954-R2.

Adsorbent for p-phenylenediamine adsorption and removal based on graphene oxide functionalized with magnetic cyclodextrin

Energy Technology Data Exchange (ETDEWEB)

Wang, Dongxue; Liu, Liangliang; Jiang, Xinyu; Yu, Jingang [College of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China); Chen, Xiaohong [Collaborative Innovation Center of Resource-conserving & Environment-friendly Society and Ecological Civilization, Changsha, 410083 (China); Chen, Xiaoqing, E-mail: xqchen@csu.edu.cn [College of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China); Collaborative Innovation Center of Resource-conserving & Environment-friendly Society and Ecological Civilization, Changsha, 410083 (China)

2015-02-28

Highlights: • Magnetic β-cyclodextrin-graphene oxide (MCG) show high adsorption capacity. • The maximum adsorption capacity was 1102.58 mg/g at 45 °C and pH 8. • MCG can be easily and fast extracted from water by magnetic attraction. • Removal rate of MCG could reach 98% after three times of adsorption. • Adsorption capacity of MCG remained at 81% after five cycles. - Abstract: Recently, graphene oxide (GO) based magnetic nanocomposites have been widely used in an adsorption-based process for the removal of organic pollutants from the water system. In this study, magnetic β-cyclodextrin-graphene oxide nanocomposites (MCG) were synthesized according to covalent binding of magnetic β-cyclodextrin nanoparticles onto the GO surface and the as-made nanocomposites were successfully applied as adsorbents for the adsorption and removal of p-phenylenediamines (PPD). The composition and morphology of prepared materials were characterized by Fourier infrared spectrometry (FT-IR), transmission electron microscopy (TEM), vibrating sample magnetometer (VSM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). Effects of pH, temperature, time and reusability on the adsorption of PPD were investigated, as well as the kinetics and isotherms parameters of the adsorbents were determined. The results indicated that the maximum adsorption capacity of MCG was 1102.58 mg/g at 45 °C and pH 8. The adsorption capacity remained at 81% after five cycles. Removal rate could reach 98% after three times of adsorption. The adsorption process with PPD was found that fitted pseudo-second-order kinetics equations and the Langmuir adsorption model. The results showed the MCG had a good adsorption ability to remove organic pollutants in wastewater.

Adsorbent for p-phenylenediamine adsorption and removal based on graphene oxide functionalized with magnetic cyclodextrin

International Nuclear Information System (INIS)

Wang, Dongxue; Liu, Liangliang; Jiang, Xinyu; Yu, Jingang; Chen, Xiaohong; Chen, Xiaoqing

2015-01-01

Highlights: • Magnetic β-cyclodextrin-graphene oxide (MCG) show high adsorption capacity. • The maximum adsorption capacity was 1102.58 mg/g at 45 °C and pH 8. • MCG can be easily and fast extracted from water by magnetic attraction. • Removal rate of MCG could reach 98% after three times of adsorption. • Adsorption capacity of MCG remained at 81% after five cycles. - Abstract: Recently, graphene oxide (GO) based magnetic nanocomposites have been widely used in an adsorption-based process for the removal of organic pollutants from the water system. In this study, magnetic β-cyclodextrin-graphene oxide nanocomposites (MCG) were synthesized according to covalent binding of magnetic β-cyclodextrin nanoparticles onto the GO surface and the as-made nanocomposites were successfully applied as adsorbents for the adsorption and removal of p-phenylenediamines (PPD). The composition and morphology of prepared materials were characterized by Fourier infrared spectrometry (FT-IR), transmission electron microscopy (TEM), vibrating sample magnetometer (VSM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). Effects of pH, temperature, time and reusability on the adsorption of PPD were investigated, as well as the kinetics and isotherms parameters of the adsorbents were determined. The results indicated that the maximum adsorption capacity of MCG was 1102.58 mg/g at 45 °C and pH 8. The adsorption capacity remained at 81% after five cycles. Removal rate could reach 98% after three times of adsorption. The adsorption process with PPD was found that fitted pseudo-second-order kinetics equations and the Langmuir adsorption model. The results showed the MCG had a good adsorption ability to remove organic pollutants in wastewater

Simulating multi-component liquid phase adsorption systems: ethanol and residual sugar

Energy Technology Data Exchange (ETDEWEB)

Jones, R.; Tezel, F.H.; Thibault, J. [Department of Chemical and Biological Engineering, University of Ottawa (Canada)], email: Jules.Thibault@uottawa.ca

2011-07-01

A series of multi-component adsorption studies was performed to determine the relative advantages of producing ethanol which is to be blended with gasoline. These studies developed a model to describe the competition for adsorption sites between ethanol and sugar molecules on the surface of the adsorbent. Three competitive adsorption models established by batch systems were examined to evaluate the suitability of the experiment data across different ethanol and sugar concentrations and determine their isotherm parameters. Multi-component packed bed adsorption experiments were then performed. The results show that ethanol capacity was decreased only slightly from that obtained in single component adsorption studies. There is significant evidence to indicate that sugar displacement from adsorption sites occurs because adsorption of ethanol is preferred. So the capacity of sugars will be greatly reduced if there are appreciable ethanol concentrations.

Adsorption of organic stormwater pollutants onto activated carbon from sewage sludge.

Science.gov (United States)

Björklund, Karin; Li, Loretta Y

2017-07-15

Adsorption filters have the potential to retain suspended pollutants physically, as well as attracting and chemically attaching dissolved compounds onto the adsorbent. This study investigated the adsorption of eight hydrophobic organic compounds (HOCs) frequently detected in stormwater - including four polycyclic aromatic hydrocarbons (PAHs), two phthalates and two alkylphenols - onto activated carbon produced from domestic sewage sludge. Adsorption was studied using batch tests. Kinetic studies indicated that bulk adsorption of HOCs occurred within 10 min. Sludge-based activated carbon (SBAC) was as efficient as tested commercial carbons for adsorbing HOCs; adsorption capacities ranged from 70 to 2800 μg/g (C initial  = 10-300 μg/L; 15 mg SBAC in 150 mL solution; 24 h contact time) for each HOC. In the batch tests, the adsorption capacity was generally negatively correlated to the compounds' hydrophobicity (log K ow ) and positively associated with decreasing molecule size, suggesting that molecular sieving limited adsorption. However, in repeated adsorption tests, where competition between HOCs was more likely to occur, adsorbed pollutant loads exhibited strong positive correlation with log K ow . Sewage sludge as a carbon source for activated carbon has great potential as a sustainable alternative for sludge waste management practices and production of a high-capacity adsorption material. Copyright © 2017 Elsevier Ltd. All rights reserved.

Equilibrium Kinetics and Thermodynamic Studies of the Adsorption of Tartrazine and Sunset Yellow

Directory of Open Access Journals (Sweden)

F. O. Okeola

2017-04-01

Full Text Available Batch adsorption experiment was carried out on freema (combination of Tartrazine and Sunset Yellow an adsorbent prepared from moringa pod. The adsorption capacity of the adsorbent was determined. Effect of such factors as initial concentration of the adsorbate solution, contact time with the adsorbent, pH of the dye solution, and temperature of the dye solution on the adsorption capacity of the absorbent was determined. The result showed that the optimum adsorption was attained at pH of 3, adsorption equilibrium was attained within 60 min. The adsorption capacity increases with increase in initial concentration of the dye solution. The result of the kinetics study showed that the adsorption process was better described by the pseudo-second order rate equation. The adsorption process fitted well with both Freundlich (R2 = 0.983 and Langmuir (R2 = 0.933 models. Thermodynamic result showed ΔH and ΔS were all negative. Gibbs free energy change (ΔG increases with increase in temperature of the dye solution.

Facile hydrothermal preparation of recyclable S-doped graphene sponge for Cu2+ adsorption

International Nuclear Information System (INIS)

Zhao, Lianqin; Yu, Baowei; Xue, Fumin; Xie, Jingru; Zhang, Xiaoliang; Wu, Ruihan; Wang, Ruijue; Hu, Zhiyan; Yang, Sheng-Tao; Luo, Jianbin

2015-01-01

Graphical abstract: S-doped graphene sponge was prepared via hydrothermal treatment, where S-doped graphene sponge had an adsorption capacity of 228 mg/g for Cu 2+ . - Highlights: • S-doped graphene sponge was prepared by hydrothermal treatment for heavy metal adsorption. • S-doped graphene sponge had a huge adsorption capacity for Cu 2+ , which was 40 times higher than that of active carbon. • S-doped graphene sponge could be easily regenerated by washing with acidic thiourea. - Abstract: Graphene sponge (GS) has been widely employed for water purification, but adsorption capacity loss frequently occurs during the formation of spongy structure. In this study, we reported the hydrothermal preparation of S-doped GS for the removal of Cu 2+ with a huge adsorption capacity of 228 mg/g, 40 times higher than that of active carbon. The adsorption isotherm could be well fitted into the Freundlich model with a K F value of 36.309 (L/mg) 1/n . The equilibrium adsorption could be fully achieved in the first 5 min. In the thermodynamics study, the negative ΔG indicated that the adsorption was spontaneous and physisorption in nature. The positive ΔH implied that the adsorption was endothermic. The changes of both pH and ionic strength had no apparent influence on the adsorption. S-doped GS could be easily regenerated by washing with acidic thiourea. Moreover, S-doped GS could be used for the adsorption of other heavy metal ions, too. The implication to the applications of S-doped GS in water treatment is discussed

[Effects of low molecular weight organic acids on redox reactions of mercury].

Science.gov (United States)

Zhao, Shi-Bo; Sun, Rong-Guo; Wang, Ding-Yong; Wang, Xiao-Wen; Zhang, Cheng

2014-06-01

To study the effects of the main component of vegetation root exudates-low molecular weight organic acids on the redox reactions of mercury, laboratory experiments were conducted to investigate the roles of tartaric, citric, and succinic acid in the redox reactions of mercury, and to analyze their interaction mechanism. The results indicated that tartaric acid significantly stimulated the mercury reduction reaction, while citric acid had inhibitory effect. Succinic acid improved the reduction rate at low concentration, and inhibited the reaction at high concentration. The mercury reduction rate by tartaric acid treatment was second-order with respect to Hg2+ concentration, ranging from 0.0014 L x (ng x min)(-1) to 0.005 6 L x (ng x min)(-1). All three organic acids showed a capacity for oxidating Hg(0) in the early stage, but the oxidized Hg(0) was subsequently reduced. The oxidation capacity of the three organic acids was in the order of citric acid > tartaric acid > succinic acid.

Competitive adsorption of heavy metals onto sesame straw biochar in aqueous solutions.

Science.gov (United States)

Park, Jong-Hwan; Ok, Yong Sik; Kim, Seong-Heon; Cho, Ju-Sik; Heo, Jong-Soo; Delaune, Ronald D; Seo, Dong-Cheol

2016-01-01

Objective of this research was to evaluate adsorption of heavy metals in mono and multimetal forms onto sesame straw biochar (SSB). Competitive sorption of metals by SSB has never been reported previously. The maximum adsorption capacities (mgg(-1)) of metals by SSB were in the order of Pb (102)≫Cd (86)≫Cr (65)>Cu (55)≫Zn (34) in the monometal adsorption isotherm and Pb (88)≫Cu (40)≫Cr (21)>Zn (7)⩾Cd (5) in the multimetal adsorption isotherm. Based on data obtained from the distribution coefficients, Freundlich and Langmuir adsorption models, and three-dimensional simulation, multimetal adsorption behaviors differed from monometal adsorption due to competition. Especially, during multimetal adsorption, Cd was easily exchanged and substituted by other metals. Further competitive adsorption studies are necessary in order to accurately estimate the heavy metal adsorption capacity of biochar in natural environments. Copyright © 2015 Elsevier Ltd. All rights reserved.

Mercury removal from liquid and solid mixed waste

International Nuclear Information System (INIS)

Gates, D.D.; Klasson, K.T.; Corder, S.L.; Cameron, P.A.; Perona, J.J.

1995-01-01

Based on bench-scale laboratory experiments, the following conclusions were reached: Sulfur-impregnated, activated, carbon pellets (Mersorb) can be used to remove mercury (Hg 2+ ) to below EPA's toxic characteristic level (0.2 mg/L). Mersorb works under acid conditions (pH 2) but its capacity is reduced by approximately 50% compared with neutral conditions. Competing ions present in the target waste stream reduced the Mersorb capacity by 50%. Mersorb appears to be economical compared with leading ion exchange resin. KI/I 2 leaching solution can be used to remove up to 99% of Hg in contaminated soil and glass. KI/I 2 leaching solution worked well with several mercury species, including Hg 0 , HgO, HgS, and HgCl 2 . KI/I 2 leaching solution worked well with a wide variety of initial mercury concentrations. Radionuclide surrogate studies suggested that uranium will not partition into KI/I 2 leaching solutions. Cesium may partition into the KI/I 2 leaching solution because of the high solubility of cesium salts

Adsorption behavior of strontium on binary mineral mixtures of Montmorillonite and Kaolinite

Energy Technology Data Exchange (ETDEWEB)

Bascetin, Elvan [Cekmece Nuclear Research and Training Center, P.K.1 34149, Atatuerk Airport, Istanbul (Turkey); Atun, Guelten [Engineering Faculty, Chemistry Department, Istanbul University, 34850 Avcilar, Istanbul (Turkey)]. E-mail: gultena@istanbul.edu.tr

2006-08-15

The adsorption behavior of kaolinite and montmorillonite minerals and their mixtures in respect of Sr ion were studied by means of a batch method using {sup 90}Sr as a radio tracer. The effect of several parameters such as temperature, pH, Sr concentration and supporting electrolyte were investigated. Experimentally measured distribution coefficients showed a good agreement to within 98.5-99.7% with theoretically calculated values. The values of adsorption capacity of adsorbents and mean adsorption energy of adsorption were calculated by fitting the adsorption data to Dubinin-Radushkevich isotherm. The adsorption capacity of clay mixtures decreased as kaolinite fractions increased. The mean adsorption energy values of 8.0-9.5 kJ mol{sup -1} showed that adsorption was governed by ion exchange. The Freundlich parameters were used to characterize a site distribution function for binary exchange between Sr and Na.

Adsorption behavior of strontium on binary mineral mixtures of Montmorillonite and Kaolinite

International Nuclear Information System (INIS)

Bascetin, Elvan; Atun, Guelten

2006-01-01

The adsorption behavior of kaolinite and montmorillonite minerals and their mixtures in respect of Sr ion were studied by means of a batch method using 90 Sr as a radio tracer. The effect of several parameters such as temperature, pH, Sr concentration and supporting electrolyte were investigated. Experimentally measured distribution coefficients showed a good agreement to within 98.5-99.7% with theoretically calculated values. The values of adsorption capacity of adsorbents and mean adsorption energy of adsorption were calculated by fitting the adsorption data to Dubinin-Radushkevich isotherm. The adsorption capacity of clay mixtures decreased as kaolinite fractions increased. The mean adsorption energy values of 8.0-9.5 kJ mol -1 showed that adsorption was governed by ion exchange. The Freundlich parameters were used to characterize a site distribution function for binary exchange between Sr and Na

Dynamic adsorption studies for the removal of Cd (II) and Ni (II) from ...

African Journals Online (AJOL)

The adsorption was found to be more effective at higher concentrations of metals and with smaller adsorbent particle size. ... Recommendation was made such that, mahogany leaves should be studied for the remediation of other heavy metals, such as lead, chromium, mercury, zinc and uranium among others. Keywords: ...

Thermal activation of serpentine for adsorption of cadmium

Energy Technology Data Exchange (ETDEWEB)

Cao, Chun-Yan [College of Land and Environment, Shenyang Agricultural University, Shenyang (China); College of Chemistry, Chemical Engineering and Food Safety, Bohai University, Jinzhou (China); Liang, Cheng-Hua, E-mail: liang110161@163.com [College of Land and Environment, Shenyang Agricultural University, Shenyang (China); Yin, Yan [Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang (China); Du, Li-Yu [College of Land and Environment, Shenyang Agricultural University, Shenyang (China)

2017-05-05

Highlights: • Thermal activated serpentine was prepared by changing heated temperature. • Thermal activated serpentine exhibited excellent adsorption behavior for cadmium. • The adsorption mechanisms could be explained as formation of CdCO{sub 3} and Cd(OH){sub 2}. • The adsorption obeyed Langmuir model and pseudo second order kinetics model. - Abstract: Thermal activated serpentine with high adsorption capacity for heavy metals was prepared. The batch experiment studies were conducted to evaluate the adsorption performance of Cd{sup 2+} in aqueous solution using thermal activated serpentine as adsorbent. These samples before and after adsorption were characterized by XRD, FT-IR, SEM, XPS, and N{sub 2} adsorption-desorption at low temperature. It was found that serpentine with layered structure transformed to forsterite with amorphous structure after thermal treatment at over 700 °C, while the surface area of the samples was increased with activated temperature and the serpentine activated at 700 °C (S-700) presented the largest surface area. The pH of solution after adsorption was increased in different degrees due to hydrolysis of MgO in serpentine, resulting in enhancing adsorption of Cd{sup 2+}. The S-700 exhibited the maximum equilibrium adsorption capacity (15.21 mg/g), which was 2 times more than pristine serpentine. Langmuir isotherm was proved to describe the equilibrium adsorption data better than Freundlich isotherm and pseudo second order kinetics model could fit the adsorption kinetics processes well. Based on the results of characterization with XPS and XRD, the adsorption mechanisms could be explained as primarily formation of CdCO{sub 3} and Cd(OH){sub 2} precipitation on the surface of serpentine.

Thermal activation of serpentine for adsorption of cadmium

International Nuclear Information System (INIS)

Cao, Chun-Yan; Liang, Cheng-Hua; Yin, Yan; Du, Li-Yu

2017-01-01

Highlights: • Thermal activated serpentine was prepared by changing heated temperature. • Thermal activated serpentine exhibited excellent adsorption behavior for cadmium. • The adsorption mechanisms could be explained as formation of CdCO_3 and Cd(OH)_2. • The adsorption obeyed Langmuir model and pseudo second order kinetics model. - Abstract: Thermal activated serpentine with high adsorption capacity for heavy metals was prepared. The batch experiment studies were conducted to evaluate the adsorption performance of Cd"2"+ in aqueous solution using thermal activated serpentine as adsorbent. These samples before and after adsorption were characterized by XRD, FT-IR, SEM, XPS, and N_2 adsorption-desorption at low temperature. It was found that serpentine with layered structure transformed to forsterite with amorphous structure after thermal treatment at over 700 °C, while the surface area of the samples was increased with activated temperature and the serpentine activated at 700 °C (S-700) presented the largest surface area. The pH of solution after adsorption was increased in different degrees due to hydrolysis of MgO in serpentine, resulting in enhancing adsorption of Cd"2"+. The S-700 exhibited the maximum equilibrium adsorption capacity (15.21 mg/g), which was 2 times more than pristine serpentine. Langmuir isotherm was proved to describe the equilibrium adsorption data better than Freundlich isotherm and pseudo second order kinetics model could fit the adsorption kinetics processes well. Based on the results of characterization with XPS and XRD, the adsorption mechanisms could be explained as primarily formation of CdCO_3 and Cd(OH)_2 precipitation on the surface of serpentine.

Adsorption of strontium on different sodium-enriched bentonites

Directory of Open Access Journals (Sweden)

Marinović Sanja R.

2017-01-01

Full Text Available Bentonites from three different deposits (Wyoming, TX, USA and Bogovina, Serbia with similar cation exchange capacities were sodium enriched and tested as adsorbents for Sr2+ in aqueous solutions. X-Ray diffraction analysis confirmed successful Na-exchange. The textural properties of the bentonite samples were determined using low-temperature the nitrogen physisorption method. Significant differences in the textural properties between the different sodium enriched bentonites were found. Adsorption was investigated with respect to adsorbent dosage, pH, contact time and the initial concentration of Sr2+. The adsorption capacity increased with pH. In the pH range from 4.0–8.5, the amount of adsorbed Sr2+ was almost constant but 2–3 times smaller than at pH ≈11. Further experiments were performed at the unadjusted pH since extreme alkaline conditions are environmentally hostile and inapplicable in real systems. The adsorption capacity of all the investigated adsorbents toward Sr2+ was similar under the investigated conditions, regardless of significant differences in the specific surface areas. It was shown and confirmed by the Dubinin–Radushkevich model that the cation exchange mechanism was the dominant mechanism of Sr2+ adsorption. Their developed microporous structures contributed to the Sr2+ adsorption process. The adsorption kinetics obeyed the pseudo-second-order model. The isotherm data were best fitted with the Langmuir isotherm model. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. III 45001

Recovery of Mercury From Contaminated Liquid Wastes

International Nuclear Information System (INIS)

1998-01-01

The Base Contract program emphasized the manufacture and testing of superior sorbents for mercury removal, testing of the sorption process at a DOE site, and determination of the regeneration conditions in the laboratory. During this project, ADA Technologies, Inc. demonstrated the following key elements of a successful regenerable mercury sorption process: (1) sorbents that have a high capacity for dissolved, ionic mercury; (2) removal of ionic mercury at greater than 99% efficiency; and (3) thermal regeneration of the spent sorbent. ADA's process is based on the highly efficient and selective sorption of mercury by noble metals. Contaminated liquid flows through two packed columns that contain microporous sorbent particles on which a noble metal has been finely dispersed. A third column is held in reserve. When the sorbent is loaded with mercury to the point of breakthrough at the outlet of the second column, the first column is taken off-line and the flow of contaminated liquid is switched to the second and third columns. The spent column is regenerated by heating. A small flow of purge gas carries the desorbed mercury to a capture unit where the liquid mercury is recovered. Laboratory-scale tests with mercuric chloride solutions demonstrated the sorbents' ability to remove mercury from contaminated wastewater. Isotherms on surrogate wastes from DOE's Y-12 Plant in Oak Ridge, Tennessee showed greater than 99.9% mercury removal. Laboratory- and pilot-scale tests on actual Y-12 Plant wastes were also successful. Mercury concentrations were reduced to less than 1 ppt from a starting concentration of 1,000 ppt. The treatment objective was 50 ppt. The sorption unit showed 10 ppt discharge after six months. Laboratory-scale tests demonstrated the feasibility of sorbent regeneration. Results show that sorption behavior is not affected after four cycles

Adsorption of molecular hydrogen on nanostructered surfaces

International Nuclear Information System (INIS)

Uranga Piña, Llinersy; Martínez Mesa, Aliezer; Seifert, Gotthard

2015-01-01

Were investigated the effect of the structural characteristics of model nanoporous environments on the adsorption of molecular hydrogen. The adsorption properties of the target nanostructures (graphene and ZnO sheets, carbon foams, metal-organic frameworks) are evaluated in a broad range of thermodynamic conditions. The study is carried out within the density functional theory for quantum fluids at finite temperature (QLDFT), which allows to account for the many-body and quantum delocalization effects in a single theoretical framework. The exchange-correlation (excess) functional is derived from the empirical equation of state of the homogeneous system. We focus on the evaluation of hydrogen storage capacities of the substrates and on the emergence of quantum effects triggered by the confinement imposed by the host structure. The approach provides accurate estimates of the hydrogen storage capacities for realistic adsorptive media. The relation between the microscopic structure of the hydrogen fluid and the calculated adsorption properties is also addressed. (full text)

Study on the adsorption of bacteria in ceramsite and their synergetic effect on adsorption of heavy metals.

Science.gov (United States)

Qiu, Shan; Ma, Fang; Huang, Xu; Xu, Shanwen

2014-01-01

In this paper, heavy metal adsorption by ceramsite with or without Bacillus subtilis (B. subtilis) immobilization was studied, and the synergetic effect of ceramsite and bacteria was discussed in detail. To investigate the roles of the micro-pore structure of ceramsite and bacteria in removing heavy metals, the amount of bacteria immobilized on the ceramsite was determined and the effect of pH was evaluated. It was found that the immobilization of B. subtilis on the ceramsite was attributed to the electrostatic attraction and covalent bond. The scanning electron microscopy results revealed that, with the presence of ceramsite, there was the conglutination of B. subtilis cells due to the cell outer membrane dissolving. In addition, the B. subtilis immobilized ceramsite showed a different adsorption capacity for different heavy metals, with the adsorption capacity ranking of La(3+) > Cu(2+) > Mg(2+) > Na(+).

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

Science.gov (United States)

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

2011-07-15

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

Copper adsorption in tropical oxisols

Directory of Open Access Journals (Sweden)

Silveira Maria Lucia Azevedo

2003-01-01

Full Text Available Cu adsorption, at concentrations between 0 to 800 mg L-1, was evaluated in surface and subsurface samples of three Brazilian soils: a heavy clayey-textured Rhodic Hapludalf (RH, a heavy clayey-textured Anionic ''Rhodic'' Acrudox (RA and a medium-textured Anionic ''Xanthic'' Acrudox (XA. After adsorption, two consecutive extractions were performed to the samples which received 100 mg L-1 copper. Surface samples adsorbed higher amounts of Cu than the subsurface, and exhibited lower Cu removed after the extractions, reinforcing the influence of the organic matter in the reactions. Cu adsorption was significant in the subsurface horizons of the Oxisols, despite the positive balance of charge, demonstrating the existence of mechanisms for specific adsorption, mainly related to the predominance of iron and aluminum oxides in the mineral fractions. In these samples, Cu was easily removed from the adsorption sites. RH demonstrated a higher capacity for the Cu adsorption in both horizons.

Equilibrium Kinetics and Thermodynamic Studies of the Adsorption of Tartrazine and Sunset Yellow

OpenAIRE

Okeola, F. O.; Odebunmi, E. O.; Ameen, O. M.; Amoloye, M. A.; Lawal, A. A.; Abdulmummeen, A. G.

2017-01-01

Batch adsorption experiment was carried out on freema (combination of Tartrazine and Sunset Yellow) an adsorbent prepared from moringa pod. The adsorption capacity of the adsorbent was determined. Effect of such factors as initial concentration of the adsorbate solution, contact time with the adsorbent, pH of the dye solution, and temperature of the dye solution on the adsorption capacity of the absorbent was determined. The result showed that the optimum adsorption was attained at pH of 3, a...

Mercury Report-Children's exposure to elemental mercury

Science.gov (United States)

... gov . Mercury Background Mercury Report Additional Resources Mercury Report - Children's Exposure to Elemental Mercury Recommend on Facebook ... I limit exposure to mercury? Why was the report written? Children attending a daycare in New Jersey ...

Adsorption of Chloroform by the Rapid Response System Filter

National Research Council Canada - National Science Library

Karwacki, Christopher

1997-01-01

Adsorption equilibria and dynamic breakthrough data were measured to determine the adsorption capacity and effect of purge air on the desorption of chloroform from activated carbon simulating the Rapid Response System (RRS) filter...

The Influence of Salt Anions on Heavy Metal Ion Adsorption on the Example of Nickel

Science.gov (United States)

Mende, Mandy; Schwarz, Dana; Steinbach, Christine; Schwarz, Simona

2018-01-01

The biodegradable polysaccharide chitosan possesses protonated and natural amino groups at medium pH values and has therefore been used as an adsorbing material for nickel salts in water treatment. Nickel is a problematic heavy metal ion which can cause various diseases and disorders in living organisms. Here, we show the influence of oxyanions (e.g., nitrate and sulfate) to the adsorption of nickel ions. Hence, simultaneously we are addressing the increasing global problem of nitrate and sulfate ion pollution in groundwater and surface water. A series of adsorption experiments was carried out in order to determine (i) the adsorption equilibrium, (ii) the adsorption capacity in dependence on the initial nickel ion concentration, and (iii) the influence of the anion presented in solution for the adsorption capacity. Surface morphology of chitosan flakes before and after the adsorption process has been studied with SEM-EDX analysis. The chitosan flakes exhibited promising adsorption capacities of 81.9 mg·g−1 and 21.2 mg·g−1 for nickel (sulfate) and nickel (nitrate), respectively. The calculated values of Gibbs free energy change ΔG0 confirm the higher adsorption of nickel ions in presence of sulfate ions. Hence, higher anion valence leads to a higher adsorption capacity. PMID:29510485

Binary boronic acid-functionalized attapulgite with high adsorption capacity for selective capture of nucleosides at acidic pH values

International Nuclear Information System (INIS)

Li, Huihui; Zhu, Shuqiang; Cheng, Ting; Wang, Shuxia; Zhu, Bin; Liu, Xiaoyan; Zhang, Haixia

2016-01-01

Boronate affinity materials have been widely used for selective capture of cis-diols such as nucleosides. Adsorbents with features of low binding pH and high adsorption capacity are highly desired. However, most reported materials only possess one of the two features. We have synthesized a 1,3,5-triazine-containing binary boronic acid by reacting cyanuric chloride with 3-amino phenylboronic acid, and the product was then grafted onto attapulgite (a fibrous aluminum-magnesium silicate). The resulting functionalized attapulgite exhibit low binding pH (5.0) and display high adsorption capacity (19.5 ± 1.1 mg⋅g"−"1 for adenosine). The material exhibits high selectivity for cis-diols even in the presence of a 1000-fold excess of interferences. It was applied to the selective extraction of nucleosides from human urine. Typical features of the method include (a) limits of detection in the range from 4 to 17 ng⋅mL"−"1, (b) limits of quantification between 13 and 57 ng⋅mL"−"1, (c) relative standard deviations of ≤9.1 %, and (d) recoveries of nucleosides from spiked human urine between 85.0 and 112.9 %. In our perception, the material and method offer a promising strategy for selective capture of cis-diols in the areas of proteomics, metabolomics and glycomics. (author)

Synthesis of magnetic wheat straw for arsenic adsorption

International Nuclear Information System (INIS)

Tian, Ye; Wu, Min; Lin, Xiaobo; Huang, Pei; Huang, Yong

2011-01-01

Highlights: → This work provides a way for fabricating low-cost arsenic adsorbents using agro- or plant-residues. → The introduction of wheat straw template highly enhances the arsenic adsorption of Fe 3 O 4 . → This magnetic adsorbent can be separated and collected by magnetic control easily and rapidly. → This adsorbent can be regenerated. → - Abstract: Magnetic wheat straw (MWS) with different Fe 3 O 4 content was synthesized by using in-situ co-precipitation method. It was characterized by powder X-ray diffraction (XRD) and vibrating sample magnetometer (VSM). This material can be used for arsenic adsorption from water, and can be easily separated by applied magnetic field. The introduction of wheat straw template highly enhanced the arsenic adsorption of Fe 3 O 4 . Among three adsorption isotherm models examined, the data fitted Langmuir model better. Fe 3 O 4 content and initial pH value influenced its adsorption behavior. Higher Fe 3 O 4 content corresponded to a higher adsorption capacity. In the pH range of 3-11, As(V) adsorption was decreased with increasing of pH; As(III) adsorption had the highest capacity at pH 7-9. Moreover, by using 0.1 mol L -1 NaOH aqueous solution, it could be regenerated. This work provided an efficient way for making use of agricultural waste.

Adsorption of diastase over natural halloysite nanotubes (HNTs)

Science.gov (United States)

Twaiq, F.; Chang, K. X.; Ling, J. Y. W.

2017-06-01

Adsorption of diastase over natural halloysite nanotubes is studied in order to evaluate the adsorption capacity of diastase. The halloysite surface characteristics were assessed using nitrogen adsorption, x-ray diffraction (XRD), thermal gravimetric analysis (TGA) and Fourier transformed infrared (FTIR). The surface area of the natural halloysite is found to be 51 m2·g-1, with total pore volume of 0.106 cm3·g-1. The natural halloysite has a basal spacing (d001) of 10 Å confirming the structure of the natural halloysite material. TGA results indicated that halloysite loses its interlayer water in the range of 30 to 105 °C and the dehydration in the structural layer above 150 °C. The dehydroxylation of halloysite has occurred at approximately 460 °C. The FTIR result of the thermally treated halloysite sample indicated that the bands observed are assigned to Si-O and Al-O bonds. The effects of solution pH and temperature were studied on the adsorption capacity and percent removal of diastase from the solution. The adsorption kinetic found to fit well with both the Pseudo first-order and Pseudo second-order models, and the values of the kinetic constant were found to be 0.173 min-1 and 0.00018 g·mg-1·min-1 respectively. The Langmuir isotherm model is found to fit well to the adsorption data and a kinetic value is found to be 0.00059 m3·g-1. The maximum adsorption capacity was found to be 370 mg·g-1, indicating the potential for applications of the natural nanostructured halloysite material as an effective adsorbent for diastase.

Effects of coal storage in air on physical and chemical properties of coal and on gas adsorption

Science.gov (United States)

Mastalerz, Maria; Solano-Acosta, W.; Schimmelmann, A.; Drobniak, A.

2009-01-01

This paper investigates changes in the high-volatile bituminous Lower Block Coal Member from Indiana owing to moisture availability and oxidation in air at ambient pressure and temperature over storage time. Specifically, it investigates changes in chemistry, in surface area, and pore structure, as well as changes in methane and carbon dioxide adsorption capacities. Our results document that the methane adsorption capacity increased by 40%, whereas CO2 adsorption capacity increased by 18% during a 13-month time period. These changes in adsorption are accompanied by changes in chemistry and surface area of the coal. The observed changes in adsorption capacity indicate that special care must be taken when collecting samples and preserving coals until adsorption characteristics are measured in the laboratory. High-pressure isotherms from partially dried coal samples would likely cause overestimation of gas adsorption capacities, lead to a miscalculation of coal-bed methane prospects, and provide deceptively optimistic prognoses for recovery of coal-bed methane or capture of anthropogenic CO2. ?? 2009 Elsevier B.V. All rights reserved.

Adsorption of aliphatic alcohols on ruthenium

International Nuclear Information System (INIS)

Shapovalova, L.B.; Zakumbaeva, G.D.

1977-01-01

The adsorption is studied of allyl-, propyl- and propargyl alcohols on a ruthenium catalyst-electrode at 20, 30 and 40 deg C in H 2 SO 4 in helium. Above adsorption has been found to grow with increased concentration of the alcohols in the solution. In solutions with the same concentration, propargyl alcohol has been noted to show highest sorptive capacity, followed by that of allyl- and propyl alcohols. With variations in the ruthenium electrode potential, alcohol adsorption occurs via maximum at potential = 0.18

The adsorption behavior of functional particles modified by polyvinylimidazole for Cu(II) ion

Energy Technology Data Exchange (ETDEWEB)

Wang, Ruixin; Men, Jiying; Gao, Baojiao [School of Chemical Engineering and Environment, North University of China, Taiyuan (China)

2012-03-15

In this paper, a novel composite material the silica grafted by poly(N-vinyl imidazole) (PVI), i.e., PVI/SiO{sub 2}, was prepared using 3-methacryloxypropyl trimethoxysilane (MPS) as intermedia through the ''grafting from'' method. The adsorption behavior of metal ions by PVI/SiO{sub 2} was researched by both static and dynamic methods. Experimental results showed that PVI/SiO{sub 2} possessed very strong adsorption ability for metal ions. For different metal ions, PVI/SiO{sub 2} exhibited different adsorption abilities with the following order of adsorption capacity: Cu{sup 2+}> Cd{sup 2+}> Zn{sup 2+}. The adsorption material PVI/SiO{sub 2} was especially good at adsorbing Cu(II) ion and the saturated adsorption capacity could reach up to 49.2 mg/g. The empirical Freundlich isotherm was found to describe well the equilibrium adsorption data. Higher temperatures facilitated the adsorption process and thus increased the adsorption capacity. The pH and grafting amount of PVI had great influence on the adsorption amount. In addition, PVI/SiO{sub 2} particles had excellent eluting and regenerating property using diluted hydrochloric acid solution as eluent. The adsorption ability trended to steady during 10 cycles. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

DNA adsorption characteristics of hollow spherule allophane nano-particles

International Nuclear Information System (INIS)

Matsuura, Yoko; Iyoda, Fumitoshi; Arakawa, Shuichi; John, Baiju; Okamoto, Masami; Hayashi, Hidetomo

2013-01-01

To understand the propensity of natural allophane to adsorb the DNA molecules, the adsorption characteristics were assessed against natural allophane (AK70), using single-stranded DNA (ss-DNA) and adenosine 5′-monophosphate (5′-AMP) as a reference molecule. The adsorption capacity of ss-DNA on AK70 exhibited one order of magnitude lower value as compared with that of 5′-AMP. The adsorption capacity of ss-DNA decreased with increasing pH due to the interaction generated between phosphate groups of ss-DNA and functional Al–OH groups on the wall perforations through deprotonating, associated with higher energy barrier for the adsorption of ss-DNA. The adsorption morphologies consisting of the individual ss-DNA with mono-layer coverage of the clustered allophane particle were observed successfully through transmission electron microscopy analysis. - Highlights: • The interaction between phosphate groups of ss-DNA and Al–OH groups • Higher energy barrier for the adsorption of ss-DNA • The individual ss-DNA with mono-layer coverage of the allophane clustered particle

Adsorptive removal of arsenic by novel iron/olivine composite: Insights into preparation and adsorption process by response surface methodology and artificial neural network.

Science.gov (United States)

Ghosal, Partha S; Kattil, Krishna V; Yadav, Manoj K; Gupta, Ashok K

2018-03-01

Olivine, a low-cost natural material, impregnated with iron is introduced in the adsorptive removal of arsenic. A wet impregnation method and subsequent calcination were employed for the preparation of iron/olivine composite. The major preparation process parameter, viz., iron loading and calcination temperature were optimized through the response surface methodology coupled with a factorial design. A significant variation of adsorption capacity of arsenic (measured as total arsenic), i.e., 63.15 to 310.85 mg/kg for arsenite [As(III) T ] and 76.46 to 329.72 mg/kg for arsenate [As(V) T ] was observed, which exhibited the significant effect of the preparation process parameters on the adsorption potential. The iron loading delineated the optima at central points, whereas a monotonous decreasing trend of adsorption capacity for both the As(III) T and As(V) T was observed with the increasing calcination temperature. The variation of adsorption capacity with the increased iron loading is more at lower calcination temperature showing the interactive effect between the factors. The adsorbent prepared at the optimized condition of iron loading and calcination temperature, i.e., 10% and 200 °C, effectively removed the As(III) T and As(V) T by more than 96 and 99%, respectively. The material characterization of the adsorbent showed the formation of the iron compound in the olivine and increase in specific surface area to the tune of 10 multifold compared to the base material, which is conducive to the enhancement of the adsorption capacity. An artificial neural network was applied for the multivariate optimization of the adsorption process from the experimental data of the univariate optimization study and the optimized model showed low values of error functions and high R 2 values of more than 0.99 for As(III) T and As(V) T . The adsorption isotherm and kinetics followed Langmuir model and pseudo second order model, respectively demonstrating the chemisorption in this

ADSORPTION AND RELEASING PROPERTIES OF BEAD CELLULOSE

Institute of Scientific and Technical Information of China (English)

A. Morales; E. Bordallo; V. Leon; J. Rieumont

2004-01-01

The adsorption of some dyes on samples of bead cellulose obtained in the Unit of Research-Production "Cuba 9"was studied. Methylene blue, alizarin red and congo red fitted the adsorption isotherm of Langmuir. Adsorption kinetics at pH = 6 was linear with the square root of time indicating the diffusion is the controlling step. At pH = 12 a non-Fickian trend was observed and adsorption was higher for the first two dyes. Experiments carried out to release the methylene blue occluded in the cellulose beads gave a kinetic behavior of zero order. The study of cytochrome C adsorption was included to test a proteinic material. Crosslinking of bead cellulose was performed with epichlorohydrin decreasing its adsorption capacity in acidic or alkaline solution.

Adsorption of cadmium (II) ions from aqueous solution by a new low-cost adsorbent-Bamboo charcoal

Energy Technology Data Exchange (ETDEWEB)

Wang Fayuan [State Key Joint Laboratory of Environment Simulation and Pollution Control, Department of Environmental Science and Engineering, Tsinghua University, Qinghuayuan, Haidian District, Beijing 100084 (China); Wang Hui, E-mail: wanghui@mail.tsinghua.edu.cn [State Key Joint Laboratory of Environment Simulation and Pollution Control, Department of Environmental Science and Engineering, Tsinghua University, Qinghuayuan, Haidian District, Beijing 100084 (China); Ma Jianwei [State Key Joint Laboratory of Environment Simulation and Pollution Control, Department of Environmental Science and Engineering, Tsinghua University, Qinghuayuan, Haidian District, Beijing 100084 (China)

2010-05-15

Batch adsorption experiments were conducted for the adsorption of Cd (II) ions from aqueous solution by bamboo charcoal. The results showed that the adsorption of Cd (II) ions was very fast initially and the equilibrium time was 6 h. High pH ({>=}8.0) was favorable for the adsorption and removal of Cd (II) ions. Higher initial Cd concentrations led to lower removal percentages but higher adsorption capacity. As the adsorbent dose increased, the removal of Cd increased, while the adsorption capacity decreased. Adsorption kinetics of Cd (II) ions onto bamboo charcoal could be best described by the pseudo-second-order model. The adsorption behavior of Cd (II) ions fitted Langmuir, Temkin and Freundlich isotherms well, but followed Langmuir isotherm most precisely, with a maximum adsorption capacity of 12.08 mg/g. EDS analysis confirmed that Cd (II) was adsorbed onto bamboo charcoal. This study demonstrated that bamboo charcoal could be used for the removal of Cd (II) ions in water treatment.

Volatile organic compound adsorption in a gas-solid fluidized bed.

Science.gov (United States)

Ng, Y L; Yan, R; Tsen, L T S; Yong, L C; Liu, M; Liang, D T

2004-01-01

Fluidization finds many process applications in the areas of catalytic reactions, drying, coating, combustion, gasification and microbial culturing. This work aims to compare the dynamic adsorption characteristics and adsorption rates in a bubbling fluidized bed and a fixed bed at the same gas flow-rate, gas residence time and bed height. Adsorption with 520 ppm methanol and 489 ppm isobutane by the ZSM-5 zeolite of different particle size in the two beds enabled the differentiation of the adsorption characteristics and rates due to bed type, intraparticle mass transfer and adsorbate-adsorbent interaction. Adsorption of isobutane by the more commonly used activated carbon provided the comparison of adsorption between the two adsorbent types. With the same gas residence time of 0.79 seconds in both the bubbling bed and fixed bed of the same bed size of 40 mm diameter and 48 mm height, the experimental results showed a higher rate of adsorption in the bubbling bed as compared to the fixed bed. Intraparticle mass transfer and adsorbent-adsorbate interaction played significant roles in affecting the rate of adsorption, with intraparticle mass transfer being more dominant. The bubbling bed was observed to have a steeper decline in adsorption rate with respect to increasing outlet concentration compared to the fixed bed. The adsorption capacities of zeolite for the adsorbates studied were comparatively similar in both beds; fluidizing, and using smaller particles in the bubbling bed did not increase the adsorption capacity of the ZSM-5 zeolite. The adsorption capacity of activated carbon for isobutane was much higher than the ZSM-5 zeolite for isobutane, although at a lower adsorption rate. Fourier transform infra-red (FTIR) spectroscopy was used as an analytical tool for the quantification of gas concentration. Calibration was done using a series of standards prepared by in situ dilution with nitrogen gas, based on the ideal gas law and relating partial pressure to gas

Adsorption and desorption characteristics of crystal violet in bottom ash column

Directory of Open Access Journals (Sweden)

Puthiya Veetil Nidheesh

2012-06-01

Full Text Available This study described adsorption of Crystal Violet (CV by bottom ash in fixed-bed column mode. Equilibrium of adsorption was studied in batch mode for finding adsorption capacity of bottom ash. In fixed bed column adsorption, the effects of bed height, feed flow rate, and initial concentration were studied by assessing breakthrough curve. The slope of the breakthrough curve decreased with increasing bed height. The breakthrough time and exhaustion time were decreased with increasing influent CV concentration and flow rates. The effect of bed depth, flow rate and CV concentration on the adsorption column design parameters were analyzed. Bed depth service time (BDST model was applied for analysis of crystal violet adsorption in the column. The adsorption capacity of bottom ash was calculated at 10% breakthrough point for different flow rates and concentrations. Desorption studies reveals that recovery of CV from bottom ash was effective by using CH3COOH than H2SO4, NaOH, HCl and NaCl solutions.

ADSORPTION AND DESORPTION CHARACTERISTICS OF CRYSTAL VIOLET IN BOTTOM ASH COLUMN

Directory of Open Access Journals (Sweden)

Puthiya Veetil Nidheesh

2012-01-01

Full Text Available This study described adsorption of Crystal Violet (CV by bottom ash in fixed-bed column mode. Equilibrium of adsorption was studied in batch mode for finding adsorption capacity of bottom ash. In fixed bed column adsorption, the effects of bed height, feed flow rate, and initial concentration were studied by assessing breakthrough curve. The slope of the breakthrough curve decreased with increasing bed height. The breakthrough time and exhaustion time were decreased with increasing influent CV concentration and flow rates. The effect of bed depth, flow rate and CV concentration on the adsorption column design parameters were analyzed. Bed depth service time (BDST model was applied for analysis of crystal violet adsorption in the column. The adsorption capacity of bottom ash was calculated at 10% breakthrough point for different flow rates and concentrations. Desorption studies reveals that recovery of CV from bottom ash was effective by using CH3COOH than H2SO4, NaOH, HCl and NaCl solutions.

Adsorptive storage of natural gas

International Nuclear Information System (INIS)

Yan, Song; Lang, Liu; Licheng, Ling

2001-01-01

The Adsorbed Natural Gas (ANG) storage technology is reviewed. The present status, theoretical limits and operational problems are discussed. Natural gas (NG) has a considerable advantage over conventional fuels both from an environmental point of view and for its natural abundance. However, as well known, it has a two fold disadvantage compared with liquid fuels: it is relatively expensive to transport from the remote areas, and its energy density (heat of combustion/volume) is low. All these will restrict its use. Compressed natural gas (CNG) may be a solution, but high pressures are needed (up to 25 MPa) for use in natural-gas fueled vehicles, and the large cost of the cylinders for storage and the high-pressure facilities necessary limit the practical use of CNG. Alternatively, adsorbed natural gas (ANG) at 3 - 4 MPa offers a very high potential for exploitation in both transport and large-scale applications. At present, research about this technology mainly focuses on: to make adsorbents with high methane adsorption capacity; to make clear the effects of heat of adsorption and the effect of impurities in natural gas on adsorption and desorption capacity. This paper provides an overview of current technology and examines the relations between fundamentals of adsorption and ANG storage. (authors)

Adsorption of phenolic compound by aged-refuse

Energy Technology Data Exchange (ETDEWEB)

Chai Xiaoli [State Key Laboratory of Pollution Control and Resource Reuse, School of Enviromental Science and Engineering, Tongji University, Siping Road 1239, Shanghai 200092 (China)]. E-mail: xlchai@mail.tongji.edu.cn; Zhao Youcai [State Key Laboratory of Pollution Control and Resource Reuse, School of Enviromental Science and Engineering, Tongji University, Siping Road 1239, Shanghai 200092 (China)

2006-09-01

The adsorption of phenol, 2-chlorophenol, 4-chlorophenol and 2,4-dichlorophenol by aged-refuse has been studied. Adsorption isotherms have been determined for phenol, 2-chlorophenol, 4-chlorophenol and 2,4-dichlorophenol and the data fits well to the Freundlich equation. The chlorinated phenols are absorbed more strongly than the phenol and the adsorption capacity has an oblivious relationship with the numbers and the position of chlorine subsistent. The experiment data suggests that both the partition function and the chemical adsorption involve in the adsorption process. Pseudo-first-order and pseudo-second-order model were applied to investigate the kinetics of the adsorption and the results show that it fit the pseudo-second-order model. More than one step involves in the adsorption process and the overall rate of the adsorption process appears to be controlled by the chemical reaction. The thermodynamic analysis indicates that the adsorption is spontaneous and endothermic.