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|Type:||Artigo de periódico|
|Title:||Ion-imprinted Polyvinylimidazole-silica Hybrid Copolymer For Selective Extraction Of Pb(ii): Characterization And Metal Adsorption Kinetic And Thermodynamic Studies|
|Abstract:||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 Pb 2+ 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 (ΔG°), enthalpy (ΔH°), and entropy (ΔS°) of the adsorption process, were found to be -16.23 kJ mol -1, -10.37 kmol -1 and -19.42 J K -1 mol -1, respectively. These results demonstrate that the adsorption of Pb 2+ 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 ΔS° 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 Pb 2+/Cu 2+, Pb 2+/Cd 2+, and Pb 2+/Zn 2+ systems. © 2011 Elsevier Ltd. All rights reserved.|
|Appears in Collections:||Unicamp - Artigos e Outros Documentos|
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