EMPLOY OF SILICA GEL ORGANICALLY MODIFIED AND IONICALLY IMPRINTED FOR SELECTIVE ON-LINE PRECONCENTRATION OF COPPER IONS

EMPLOY OF SILICA GEL ORGANICALLY MODIFIED AND IONICALLY IMPRINTED FOR SELECTIVE ON-LINE PRECONCENTRATION OF COPPER IONS. The present work purposes the preparation of a silica gel sorbent organically modified with 2-aminoethyl-3-aminobutylmethyldimethoxysilane (AAMDMS) and imprinted with Cu(2+) ions by means surface imprinting technique and its use for selective on-line sorbent preconcentration of Cull ions with further UV-VIS spectrophotometric determination by flow injection analysis. The Cu(2+)-imprinted silica gel, when compared with non imprinted silica gel and silica gel, showed from the binary mixture Of Cu(2+)/Ni(2+) relative selectivity coefficient (k') of 6.84 and 5.43 and 6.64 and 19.83 for the mixture Cu(2+)/Pb(2+), thus demonstrating higher selectivity of Cu(2+)-imprinted silica gel towards Cull ions. Under optimized condition, the on-fine preconcentration method provided detection limit of 3.4 mu g L(-1) and linear range ranging from 30.0 up to 300.0 mu g L(-1) (r = 0.995). The accuracy of method was successfully assessed by analyzing different kind of spiked water samples with recovery values ranging from 92.2 up to 103.0%.33230130

Contamination from an affluent of Furnas reservoir by trace metals

This study aims to determine concentrations and characterize trace metals distribution in an affluent of Furnas reservoir, Alfenas-MG. Water and sediment samples were taken monthly, 2010/10-2011/07 in five sites of Córrego do Pântano for subsequent determination of Pb, Cd and Zn levels by chemical analysis. The stream studied is in disagreement with Brazilian legislation for Class II water bodies (CONAMA 357). The highlights are the unsuitable concentrations of Pb for human consumption, according to Ministry of Health 2914 decree, providing risk for population

Contamination from an affluent of Furnas reservoir by trace metals

This study aims to determine concentrations and characterize trace metals distribution in an affluent of Furnas reservoir, Alfenas-MG. Water and sediment samples were taken monthly, 2010/10-2011/07 in five sites of Córrego do Pântano for subsequent determination of Pb, Cd and Zn levels by chemical analysis. The stream studied is in disagreement with Brazilian legislation for Class II water bodies (CONAMA 357). The highlights are the unsuitable concentrations of Pb for human consumption, according to Ministry of Health 2914 decree, providing risk for population

Ion-imprinted polyvinylimidazole-silica hybrid copolymer for selective extraction of Pb(II): Characterization and metal adsorption kinetic and thermodynamic studies

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)The current paper presents a synthesis of a novel ion-imprinted hybrid copolymer (IIHC)[poly(1-vinylimidazole)-co-(3-(trimethoxysilyl)propyl methacrylate) and its application to selective adsorption of Pb2+ ions. The hybrid copolymer was prepared by coupling free radical addition and sol-gel processing, using tetraethoxysilane (TEOS) as cross-linker. Thermogravimetry (TG), FT-IR, X-ray diffraction, specific surface area (BET) and scanning electron microscopy (SEM) were used to characterize the copolymers. The equilibrium data obtained were fitted very well to the non-linear Langmuir-Freundlich isotherm model, as compared to other models, and the maximum adsorption uptake was found to be 7.6 mg g(-1). The thermodynamic parameters, including Gibbs free energy (Delta G degrees). enthalpy (Delta H degrees), and entropy (Delta S degrees) of the adsorption process, were found to be -16.23 kJ mol(-1), -10.37 kmol(-1) and -19.42J K-1 mol(-1), respectively. These results demonstrate that the adsorption of Pb2+ onto the hybrid copolymer takes place by a spontaneous and exothermic process with further decrease in the degree of freedom without disordering at the solid-solution interface due to the negative Delta S degrees value. Furthermore, the pseudo-first-order and pseudo-second-order models were used to describe the kinetic data. The experimental data were fitted well to the pseudo-first-order kinetics. Under competitive adsorption conditions, the ion-imprinted hybrid copolymer was 8.8, 64.9 and 16 times more selective when compared to the blank copolymer (NIC - non-imprinted copolymer) for Pb2+/Cu2+, Pb2+/Cd2+, and Pb2+/Zn2+ systems. (C) 2011 Elsevier Ltd. All rights reserved.7218391Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundacao AraucariaFundação de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)INCT for Bioanalytics (Instituto Nacional de Ciencia e Tecnologia de Bioanalitica)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES