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Adsorption of Pb(2+), Cu(2+) and Cd(2+) in FDU-1 silica and FDU-1 silica modified with humic acid

Silva, Luis Carlos Cides da; SANTOS, L. B. O. dos; Abate, Gilberto; Cosentino, Ivana Conte; Fantini, Marcia Carvalho de Abreu; MASINI, J. C.; MATOS, J. R.
Fonte: ELSEVIER SCIENCE BV Publicador: ELSEVIER SCIENCE BV
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
617.92996%
Ordered mesoporous silica with cubic structure, type FDU-1, was synthesized under strong acid media using B-50-6600 poly(ethylene oxide)-poly(butilene oxide)-poly(ethylene oxide) triblock copolymer (EO(39)BO(47)EO(39)) and tetraethyl orthosilicate (TEOS). Humic acid (HA) was modified to the synthesis process at a concentration of 1.5 mmol per gram of SiO(2). Thermogravimetry, small angle X-ray diffraction, nitrogen adsorption and high resolution transmission electron microscopy were used to characterize the samples. The pristine FDU-1 and FDU-1 with incorporated 1.5 mmol of HA were tested for adsorption of Pb(2+), Cu(2+) and Cd(2+) in aqueous solution. Incorporation of humic acid into the FDU-1 silica afforded an adsorbent with strong affinity for Cd(2+), Cu(2+) and Pb(2+) from single ion solutions. Adsorption of Cu(2+) was significantly enhanced after incorporation of humic acid, a fact that can be explained by the formation of complexes with carboxylic and phenolic groups at low concentrations of the metal cation. The results demonstrated the potential applicability of FDU-1 with incorporated HA in the removal of low concentrations of heavy metal cations from aqueous solution, such as wastewaters, after usual precipitation of metal hydroxides in alkaline medium and proper pH conditioning in the range between 6 and 7. (C) 2007 Elsevier Inc. All rights reserved.

Adsorção competitiva de cádmio, cobre, níquel e zinco em solos.; Competitive adsorption of cadmium, copper, nickel and zinc in soils.

Moreira, Cindy Silva
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 09/09/2004 PT
Relevância na Pesquisa
534.89902%
Dentre os processos envolvidos no comportamento e biodisponiblidade dos metais pesados nos solos, aqueles relacionados com a adsorção são de grande importância. Tendo em vista a natureza multielementar do sistema solo-solução e a complexidade das reações envolvidas, o conhecimento dos mecanismos de adsorção em sistemas competitivos permite uma avaliação mais realista do comportamento dos metais no solo. Os objetivos desse trabalho foram (i) avaliar a adsorção competitiva de cádmio, cobre, níquel e zinco, tomadas da camada mais superficial (horizonte A) de 14 solos representativos dos do Estado de São Paulo; (ii) obter isotermas de adsorção em sistemas competitivo e não-competitivo, utilizando a equação matemática de Langmuir para simular a adsorção; (iii) estabelecer seqüências de afinidade metálica para cada solo e (iv) estabelecer a relação entre o comportamento adsortivo dos metais e alguns atributos dos solos, mediante estudos de correlações simples e regressões múltiplas. Ao correspondente a 2,0 g de terra foram adicionados 20 mL de solução 0,01 mol L-1 de NaNO3 (relação 1:10) contendo concentrações equimolares (0,017; 0,034; 0,085; 0,17; 0,255; 0,51; 0,85 e 1,275 mmol L-1) de Cu...

"A utilização de turfa como adsorvente de metais pesados. O exemplo da contaminação da Bacia do Rio Ribeira de Iguape por chumbo e metais associados" ; "The utilization of peat as heavy metal adsorbent. The example of the contamination of Ribeira do Iguape River catchment by lead and associated minerals"

Franchi, José Guilherme
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 19/11/2004 PT
Relevância na Pesquisa
599.8257%
Este trabalho teve como objetivos principais a caracterização da mina de turfa de Eugênio de Melo, localizada no Estado de São Paulo, região do Vale do Rio Paraíba do Sul, bem como uma amostra representativa do seu minério. Esta amostra foi testada sob duas condições – in natura e tratada com ácido clorídrico – como adsorvente de metais pesados visando a aplicação do minério em processos de tratamento de efluentes líquidos. Adotaram-se como estudos de caso lixívias obtidas a partir de resíduos da mineração de sulfetos de chumbo e metais associados existentes na região do alto curso do Rio Ribeira de Iguape, geradas em laboratório. Tais depósitos encontram-se sob a forma de extensos corpos às margens de importantes drenagens, circunscritas à região de Adrianópolis (PR). A possibilidade de liberação dos metais pesados presentes nestes depósitos para o ambiente foi avaliada através de estudos granulométricos, mineralógicos e químicos de uma coluna amostrada num destes depósitos. Os teores dos metais presentes nas lixívias enquadraram-nas como não passíveis de descarte para o ambiente sem tratamento prévio, segundo a legislação estadual e federal que regem o assunto. Os resíduos da mineração aqui estudados...

Adsorção e dessorção de Cd, Cu, Ni e Zn, em solo tratado com lodo de esgoto; Adsorption and dessorption of Cd, Cu, Ni e Zn in sewage sludge amended soil

Mellis, Estevão Vicari
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 09/02/2007 PT
Relevância na Pesquisa
612.62758%
O destino de metais pesados em solos é principalmente controlado por reações de sorção e de precipitação em superfícies minerais. Resultados de pesquisa têm evidenciado certa contradição quanto à mobilidade dos metais pesados em solos tratados com lodo de esgoto. Parte dos resultados permite afirmar que a mobilidade dos metais nesses solos é baixa ou nula, enquanto que outra parcela questiona a capacidade do solo em reter esses elementos, sendo esta capacidade função de fatores como tempo, nível de contaminação, condições climáticas, alterações químicas e degradação da matéria orgânica. O objetivo do trabalho foi avaliar a dessorção de Cd, Cu, Ni e Zn em função do pH, a capacidade adsortiva e a fitodisponibilidade desses metais em um Latossolo tratado por cinco anos consecutivos com doses de lodos provenientes das estações de tratamento de Barueri (LB) e de Franca (LF). Amostras de solo foram coletadas da camada 0-0,2m, dos seguintes tratamentos: testemunha; dose de lodo estabelecida para adubação nitrogenada da cultura do milho (1N); duas vezes (2N), quatro vezes (4N) e oito vezes a dose de lodo recomendada (8N). O efeito do pH na dessorção dos metais foi avaliado por meio da determinação da concentração dos mesmos em extratos obtidos em agitações seqüenciais...

Adsorção individual e competitiva de Cd, Cu, Ni e Zn em solos em função da variação de pH; Individual and competitive adsorption of Cd, Cu, Ni and Zn in soils as a function of pH variation

Lopes, Cintia Masuco
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 17/03/2009 PT
Relevância na Pesquisa
536.65156%
A disposição de resíduos sólidos ou a aplicação de pesticidas e fertilizantes podem levar ao aumento da concentração de elementos potencialmente tóxicos, especialmente os metais pesados, em solos e águas subterrâneas. Como o solo vem sendo considerado potencial depósito para disposição desses resíduos, é importante conhecer os mecanismos de retenção e transporte destes elementos para minimizar seu impacto ao ambiente. Uma maneira de avaliar o comportamento de um metal no solo é por meio de estudos de adsorção. Avaliou-se o efeito da variação do pH na adsorção de metais pesados, em sistemas individual e competitivo, em amostras da camada superficial (0-0,2 m) de 30 solos representativos do Estado de São Paulo. Isotermas de adsorção foram elaboradas após adição de 10 a 200 mg L-1 de Cd, Cu, Ni e Zn, na forma de nitrato, tendo a solução de NaNO3 0,01 mol L-1 como eletrólito suporte. O efeito do pH na adsorção dos metais foi avaliado por meio da adição de 20 ml de uma solução de NaNO3 0,01 mol L-1 com 0,1 mol L-1 de cada um dos quatro metais. O ajuste do pH foi feito ou com HNO3 ou com NaOH, procurando-se obter valores entre 4 a 7. Após agitação das amostras e posterior centrifugação, foram feitas determinações dos metais na solução de equilíbrio. A quantidade de metal adsorvida foi calculada pela diferença entre a concentração adicionada e a remanescente na solução de equilíbrio. A partir dos resultados experimentais...

Study on soluble heavy metals with preconcentration by using a new modified oligosilsesquioxane sorbent

Vieira, Eduardo G.; Soares, Isaac V.; Dias Filho, Newton L.; da Silva, Nileia C.; Perujo, Sergio D.; Bastos, Andrea C.; Garcia, Edemir F.; Ferreira, Tamires T.; Fraceto, Leonardo F.; Rosa, Andre H.
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 215-222
ENG
Relevância na Pesquisa
606.15984%
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); Processo FAPESP: 11/18086-3; In this work, a new modified oligosilsesquioxane was prepared, characterized and evaluated for its heavy metal adsorption characteristics from aqueous solution. The material was characterized using infrared spectroscopy, X-ray diffractometry, solid-state Si-29 and C-13 nuclear magnetic resonance. Batch and column experiments were conducted to investigate for Fe (III), Cr (III), Cu (II), Cd (II), Pb (II) and Ni (II) removal from dilute aqueous solution by sorption onto modified oligosilsesquioxane. The results obtained in the flow experiments, showed a recovery of ca. 100% of the metal ions adsorbed in a column packed with 2.0 g of nanomaterial, using 3 mL of 1.0 mol L-1 HCl solution as eluent. The detection limits for Fe, Cr, Cu, Cd, Pb, and Ni were 0.26, 0.33, 0.38, 0.41, 0.47 and 0.55 mu g L-1, respectively. The relative standard deviation values (n = 12) were <4.82% for Fe, <4.12% for Cr, <3.79% for Cu, <3.03% for Cd, <4.02% for Pb and <2.65% for Ni. The proposed method was successfully applied to the analysis of environmental samples.

Study of an organically modified clay: Selective adsorption of heavy metal ions and voltammetric determination of mercury(II)

Dias, N. L.; do Carmo, D. R.
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 919-927
ENG
Relevância na Pesquisa
607.4237%
In this work, a hydrophilic clay, Na-montmorillonite from Wyoming, USA, was rendered organophilic by exchanging the inorganic interlayer cations for hexaclecyltrimethylammonium ions (HDTA), with the formulae of [(CH3)(3)N(C16H33)](+) ion. Based on fact that organo-clay has high affinities for non-ionic organic molecules, 1,3,4-thiadiazole-2,5-dithiol was loaded oil the HDTA-montmorillonite surface, resulting in the 1,3,4-thiadiazole-2,5-dithiol-HDTA-montmorillonite complex (TDD-organo-clay).The following properties of TDD-organo-clay are discussed: selective adsorption of heavy metal ions measured by batch and chromatographic column techniques, and utilization as preconcentration agent in a chemically modified carbon paste electrode (CMCPE) for determination of mercury(II).The main point of this paper is the construction of a selective sensor, a carbon paste electrode modified with TDD-organo-clay, its properties and its application to the determination of mercury(II) ions, as this element belongs to the most toxic metals. The chemical selectivity of this functional group and the selectivity of voltammetry were combined for preconcentration and determination. (c) 2005 Elsevier B.V. All rights reserved.

2-Mercaptobenzothiazole clay as matrix for sorption and preconcentration of some heavy metals from aqueous solution

Dias Filho, Newton L.; Gushikem, Yoshitaka; Polito, Wagner L.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 167-172
ENG
Relevância na Pesquisa
614.93664%
2-Mercaptobenzothiazole loaded on previously polystyrene treated clay was prepared, characterized and used for sorption and preconcentration of Hg(II) Pb(II), Zn(II) and Cd(II) from an aqueous solution. The support used was a natural clay previously treated with sulphuric acid solution. Adsorptiou isotherms of metal ions from aqueous solutions as function of pH were studied at 298 K. Conditions for quantitative retention and elution were established for each metal by batch and column methods. The chemically treated clay was very selective to Hg(II) in solution in which Zn(II), Cd(II), Pb(II) and some transition metal ions were also present.

Produção e caracterização de quitosana imobilizada em substratos visando adsorção de ions metalicos; Production and characterization of chitosan immobilized on substrates targeting metal ions adsorption

Juliana Queiroz Albarelli
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 15/12/2009 PT
Relevância na Pesquisa
624.6686%
A quitosana é um polímero natural muito estudado devido à sua boa capacidade adsorvente. A aplicação deste biopolímero para remoção de metais pesados tem sido estudada desde o início dos anos 1970 sendo que o número de trabalhos sobre este tema cresceu rapidamente desde então. No entanto, o uso da quitosana como adsorvente em maior escala enfrenta alguns obstáculos, devido à sua baixa resistência mecânica. Uma possível alternativa para melhorar aspectos mecânicos e que também contribui para uma melhor transferência de massa do adsorbato no adsorvente é a imobilização da quitosana em matrizes sólidas utilizando-se técnicas de recobrimento de partículas. Neste contexto, este trabalho visou investigar a imobilização da quitosana em substratos para a aplicação em sistemas de adsorção. Inicialmente foram testados como suporte para imobilização da quitosana vidro, polipropileno, borracha vulcanizada, porcelana e tecido de algodão. O substrato de vidro, utilizado na forma de esferas, apresentou melhor interação com a solução de recobrimento e características adequadas para aplicação em processos de adsorção. As esferas de vidro foram recobertas por diferentes métodos utilizando quitosana 2,5% (m/v) em solução de ácido acético 3% (v/v). O material recoberto foi utilizado em sistemas de adsorção em batelada e contínuo a fim de se analisar a capacidade de remoção de cobre pelo filme de quitosana. Dentre as diferentes técnicas de revestimento estudadas...

Adsorption isotherm studies of Cd (II), Pb (II) and Zn (II) ions bioremediation from aqueous solution using unmodified and EDTA-modified maize cob

Igwe,J.C; Abia,A.A.
Fonte: Fundação Editora da Universidade Estadual Paulista Júlio de Mesquita Filho - UNESP Publicador: Fundação Editora da Universidade Estadual Paulista Júlio de Mesquita Filho - UNESP
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2007 EN
Relevância na Pesquisa
626.52023%
The need to clean-up heavy metal contaminated environment can not be over emphasized. This paper describes the adsorption isotherm studies of Cd (II), Pb (II) and Zn (II) ions from aqueous solution using unmodified and EDTA-modified maize cob. Maize cob was found to be an excellent adsorbent for the removal of these metal ions. The amount of metal ions adsorbed increased as the initial concentration increased. Also, EDTA - modification enhanced the adsorption capacity of maize cob probably due to the chelating ability of EDTA. Among the three adsorption isotherm tested, Dubinin-Radushkevich gave the best fit with R² value ranging from 0.9539 to 0.9973 and an average value of 0.9819. This is followed by Freundlich isotherm (Ave. 0.9783) and then the Langmuir isotherm (Ave. 0.7637). The sorption process was found to be a physiosorption process as seen from the apparent energy of adsorption which ranged from 2.05KJmol to 4.56KJmol. Therefore, this study demonstrates that maize cob which is an environmental pollutant could be used to adsorb heavy metals and achieve cleanliness thereby abating environmental nuisance caused by the maize cob.

Heavy metal partition in acid soils contaminated by coal power plant

Camargo,I.M.C.; Hiromoto,G.; Flues,M.
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2007 EN
Relevância na Pesquisa
597.71367%
Metal partition coefficient (Kp) may vary by several orders of magnitude because of the different soil characteristics. Therefore, for human health risk assessment it is important to determine the specific soil metal Kp. For the coal-fired Figueira (Figueira county, north of Parana State) power plant surrounding soil, two different extraction methods representing the soil liquid phase were used to determine the Kp of soil samples: an EDTA and a Ca(NO3)2 extracting solution. In general, KpCa(NO3)2 values showed more variability and were higher than KpEDTA. KpCa(NO3)2/KpEDTA ratio for Cd, Ni and Zn was close to one, while Co, Cr, Cu and Pb ratios were higher than two. Subsequent KpEDTA and KpCa(NO3)2 analyses showed similar soil adsorption for all metals, except Pb. Concerning the Figueira soil case, because of the relatively low KpCa(NO3)2/ KpEDTA ratio (except for Pb), both Kp values could be used for conducting human health risk assessment with mathematical models.

Biosolids and heavy metals in soils

Silveira,Maria Lucia Azevedo; Alleoni,Luís Reynaldo Ferracciú; Guilherme,Luiz Roberto Guimarães
Fonte: São Paulo - Escola Superior de Agricultura "Luiz de Queiroz" Publicador: São Paulo - Escola Superior de Agricultura "Luiz de Queiroz"
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2003 EN
Relevância na Pesquisa
633.1095%
The application of sewage sludge or biosolids on soils has been widespread in agricultural areas. However, depending on their characteristics, they may cause increase in heavy metal concentration of treated soils. In general, domestic biosolids have lower heavy metal contents than industrial ones. Origin and treatment method of biosolids may markedly influence their characteristics. The legislation that controls the levels of heavy metal contents in biosolids and the maximum concentrations in soils is still controversial. In the long-term, heavy metal behavior after the and of biosolid application is still unknown. In soils, heavy metals may be adsorbed via specific or non-specific adsorption reactions. Iron oxides and organic matter are the most important soil constituents retaining heavy metals. The pH, CEC and the presence of competing ions also affect heavy metal adsorption and speciation in soils. In solution, heavy metals can be present either as free-ions or complexed with organic and inorganic ligands. Generally, free-ions are more relevant in environmental pollution studies since they are readily bioavailable. Some computer models can estimate heavy metal activity in solution and their ionic speciation. Thermodynamic data (thermodynamic stability constant)...

Study on the adsorption of heavy metal ions from aqueous solution on modified SBA-15

Giraldo,Liliana; Moreno-Piraján,Juan Carlos
Fonte: ABM, ABC, ABPol Publicador: ABM, ABC, ABPol
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/08/2013 EN
Relevância na Pesquisa
622.49645%
Amino-functionalized SBA-15 mesoporous silica was prepared, characterized, and used as an adsorbent for heavy metal ions. The organic - inorganic hybrid material was obtained by a grafting procedure using SBA-15 silica with 3-aminopropyl-triethoxysilane and bis(2,4,4-trimethylpentyl) phosphinic acid (Cyanex 272), respectively. The structure and physicochemical properties of the materials were characterized by means of elemental analysis, X-ray diffraction (XRD), nitrogen adsorption - desorption, thermogravimetric analysis, FTIR spectroscopy and immersion calorimetry. The organic functional groups were successfully grafted onto the SBA-15 surface and the ordering of the support was not affected by the chemical modification. The behavior of the grafted solids was investigated for the adsorption of heavy metal ions from aqueous solutions. The hybrid materials showed high adsorption capacity and high selectivity for zinc ions. Other ions, such as cooper and cobalt were absorbed by the modified SBA-15 material.

Application of a bacterial extracellular polymeric substance in heavy metal adsorption in a co-contaminated aqueous system

Martins,Paula Salles de Oliveira; Almeida,Narcisa Furtado de; Leite,Selma Gomes Ferreira
Fonte: Sociedade Brasileira de Microbiologia Publicador: Sociedade Brasileira de Microbiologia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2008 EN
Relevância na Pesquisa
597.9614%
The application of a bacterial extracellular polymeric substance (EPS) in the bioremediation of heavy metals (Cd, Zn and Cu) by a microbial consortium in a hydrocarbon co-contaminated aqueous system was studied. At the low concentrations used in this work (1.00 ppm of each metal), it was not observed an inhibitory effect on the cellular growing. In the other hand, the application of the EPS lead to a lower concentration of the free heavy metals in solution, once a great part of them is adsorbed in the polymeric matrix (87.12% of Cd; 19.82% of Zn; and 37.64% of Cu), when compared to what is adsorbed or internalized by biomass (5.35% of Cd; 47.35% of Zn; and 24.93% of Cu). It was noted an increase of 24% in the consumption of ethylbenzene, among the gasoline components that were quantified, in the small interval of time evaluated (30 hours). Our results suggest that, if the experiments were conducted in a larger interval of time, it would possibly be noted a higher effect in the degradation of gasoline compounds. Still, considering the low concentrations that were evaluated, it is possible that a real system could be bioremediated by natural attenuation process, demonstrated by the low effect of those levels of contaminants and co-contaminants over the naturally present microbial consortium.

Heavy Metal Adsorption onto Kappaphycus sp. from Aqueous Solutions: The Use of Error Functions for Validation of Isotherm and Kinetics Models

Rahman, Md. Sayedur; Sathasivam, Kathiresan V.
Fonte: Hindawi Publishing Corporation Publicador: Hindawi Publishing Corporation
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
627.5453%
Biosorption process is a promising technology for the removal of heavy metals from industrial wastes and effluents using low-cost and effective biosorbents. In the present study, adsorption of Pb2+, Cu2+, Fe2+, and Zn2+ onto dried biomass of red seaweed Kappaphycus sp. was investigated as a function of pH, contact time, initial metal ion concentration, and temperature. The experimental data were evaluated by four isotherm models (Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich) and four kinetic models (pseudo-first-order, pseudo-second-order, Elovich, and intraparticle diffusion models). The adsorption process was feasible, spontaneous, and endothermic in nature. Functional groups in the biomass involved in metal adsorption process were revealed as carboxylic and sulfonic acids and sulfonate by Fourier transform infrared analysis. A total of nine error functions were applied to validate the models. We strongly suggest the analysis of error functions for validating adsorption isotherm and kinetic models using linear methods. The present work shows that the red seaweed Kappaphycus sp. can be used as a potentially low-cost biosorbent for the removal of heavy metal ions from aqueous solutions. Further study is warranted to evaluate its feasibility for the removal of heavy metals from the real environment.

BATCH AND BENCH-SCALE FIXED-BED COLUMN EVALUATIONS OF HEAVY METAL REMOVALS FROM AQUEOUS SOLUTIONS AND SYNTHETIC LANDFILL LEACHATE USING LOW-COST NATURAL ADSORBENTS

Li, Chenxi
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado Formato: 5000314 bytes; application/pdf
EN; EN
Relevância na Pesquisa
831.5999%
In this project, three separate experiments were conducted to assess heavy metal removal from metal aqueous solutions and synthetic landfill leachate by adsorption using low-cost natural adsorbents. Fundamental batch investigations indicated that the 4.0-4.75 mm crushed mollusk shells and the Sphagnum peat moss were the best adsorbents for cadmium and nickel removal, respectively. Peat moss was also found to have the highest adsorption capacities for manganese and cobalt adsorption. The adsorption capacities of the peat moss and crushed mollusk shells used as natural adsorbents for the adsorption of cadmium and nickel from binary aqueous solutions in fixed-bed columns under continuous flow conditions were investigated. The life expectancy of each adsorbent in the fixed-bed columns was also assessed for different hydraulic loading rates. The flow rate of 1.5 mL/min (surface loading of 27.52 cm3/cm2•day) and bed depth of 15 cm were identified as the better operational conditions from the column testing. The results indicated that 47.9% and 42.7% cadmium and nickel removal efficiencies could obtained under these operational conditions, respectively. Finally, the peat moss and the crushed mollusk shells were packed in bench-scale down-flow fixed-bed columns to evaluate their adsorption capacities as natural low-cost adsorbents for the removal of heavy metals from aerated and non-aerated synthetic landfill leachate. The flow rate applied in this operation was 1.5 mL/min (surface loading of 27.52 cm3/cm2•day). Peat was found to have the best adsorption capacities in columns treating aerated synthetic leachate for cadmium (78.6%) and nickel (83.8%) removal efficiencies.; Thesis (Master...

Dendrimer modified magnetite particles for heavy metal (copper(II), cobalt(II), zinc(II), nickel(II)) removal from water

Liu, Xuesong
Fonte: University of Delaware Publicador: University of Delaware
Tipo: Tese de Doutorado
Relevância na Pesquisa
731.5999%
Huang, Chin-Pao; In this study, magnetite particles were synthesized and functionalized with (3-aminopropyl)trimethoxysilane (APTS) to obtain Generation 0 Poly(amidoamine) (PAMAM) dendrimer modified magnetite particles. Particles were tested for the adsorption of Cu(II), Co(II), Zn(II), and Ni(II) from aqueous system. Magnetite particles were synthesized by coprecipitation under optimized reaction condition. Various parameters that may affect particle size, such as iron ratio, temperature, heating time, and mixing speed were tested. X-ray Diffraction (XRD), Vibrating Sample Magnetometer (VSM), Dynamic Light Scattering (DLS), and Zeta-potential were used to characterize magnetite particles. XRD shows particles were in the form of Fe 3 O4 ; VSM shows that the saturate magnetic moment of magnetite was 60.8 emu/g; DLS shows that the diameter of particle was 158 ?? 8 nm; pHzpc was 4.4. To modify the magnetite, APTS was introduced to form G0 (1st generation) dendrimer on the surface of magnetite particle. Zeta-potential was used to characterize the particle and it showed that the pHzpc of dendrimer modified particle was 9.6. Four heavy metal, Cu(II), Co(II), Zn(II), and Ni(II), were used as adsorbate to test the metal adsorption capacity of this material. Cu(II)...

Biossólidos e metais pesados em solos; Biosolids and heavy metals in soils

Silveira, Maria Lucia Azevedo; Alleoni, Luís Reynaldo Ferracciú; Guilherme, Luiz Roberto Guimarães
Fonte: Universidade de São Paulo. Escola Superior de Agricultura Luiz de Queiroz Publicador: Universidade de São Paulo. Escola Superior de Agricultura Luiz de Queiroz
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; ; ; ; ; Formato: application/pdf
Publicado em 01/12/2003 ENG
Relevância na Pesquisa
633.72805%
The application of sewage sludge or biosolids on soils has been widespread in agricultural areas. However, depending on their characteristics, they may cause increase in heavy metal concentration of treated soils. In general, domestic biosolids have lower heavy metal contents than industrial ones. Origin and treatment method of biosolids may markedly influence their characteristics. The legislation that controls the levels of heavy metal contents in biosolids and the maximum concentrations in soils is still controversial. In the long-term, heavy metal behavior after the and of biosolid application is still unknown. In soils, heavy metals may be adsorbed via specific or non-specific adsorption reactions. Iron oxides and organic matter are the most important soil constituents retaining heavy metals. The pH, CEC and the presence of competing ions also affect heavy metal adsorption and speciation in soils. In solution, heavy metals can be present either as free-ions or complexed with organic and inorganic ligands. Generally, free-ions are more relevant in environmental pollution studies since they are readily bioavailable. Some computer models can estimate heavy metal activity in solution and their ionic speciation. Thermodynamic data (thermodynamic stability constant)...

Study of the behavior of metal adsorption in acid solutions on lignin using a comparison of different adsorption isotherms

Pérez,N.; Sánchez,M.; Rincón,G.; Delgado,L.
Fonte: Latin American applied research Publicador: Latin American applied research
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/04/2007 EN
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608.86164%
The adsorption process of Nickel and Vanadium dissolved in acid liquor on lignin is studied in this work. Different adsorption isotherm models are used to adjust liquid-solid systems: Langmuir, Freundlich and Redlich-Peterson. It was obtained that the metal adsorption using lignin proceeds by similar chemical mechanisms. Possibly the Nickel is adsorbed in heterogeneous monolayers, contrary to Vanadium which is adsorbed in homogeneous ones. Results of the parameters obtained for every adsorption model and adsorption system are reported too.

Comparative study of EVA-Cloisite® 20A and heat-treated EVA-Cloisite® 20A on heavy-metal adsorption properties

Dlamini,Derrick S; Mishra,Ajay K; Mamba,Bhekie B
Fonte: Water SA Publicador: Water SA
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2012 EN
Relevância na Pesquisa
710.9535%
Ethylene vinyl acetate (EVA)/ Cloisite® 20A (C20A) composite fabricated via the melt-blending method was used for the development of a heavy-metal adsorbent through acid and heat treatment. Heat-treated composites were produced at 400°C to 1 000°C in air and N2 atmospheres. The materials were characterised through TGA, FT-IR, contact angle and Zetasizer. Treating EVA/C20A composites with H2SO, at 130°C reduced the contact angle from 99.73° to 30.40°. The acid-function-alised composite was tested for the removal of Pb²+ and an adsorption capacity of 49 mg-g-1 was recorded while the heat-treated composite exhibited an adsorption capacity of 153 mg-g-1.