Chemical Engineering Journal, Vol.193, 21-30, 2012
Equilibrium and kinetic study of arsenic sorption by water-insoluble nanocomposite resin of poly[N-(4-vinylbenzyl)-N-methyl-D-glucamine]-montmorillonite
This research presents the kinetic and equilibrium performance of arsenic sorption by a novel polymerclay nanocomposite ion exchange resin. The monomer N-(4-vinylbenzyl)-N-methyl-D-glucamine was previously synthesised and subsequently polymerised via radical initiation in the presence of crosslinking reagent N,N-methylene-bis-acrylamide and organic-modified montmorillonite. The sorption of arsenic(V) was studied as a function of time, initial concentration and pH. Experiments as a function of pH revealed that arsenic sorption was favoured in the pH range from 3 to 6. The experimental data were fitted to kinetic and diffusion models, such as pseudo-first order, pseudo-second order. Elovich, and the intra-particle diffusion model. The pseudo-second order model presented the best correlation with the experimental data. The model indicated that high percentages of retention could be achieved in a short time (>90%, 1 h of contact) at pH 6 when the initial arsenic concentration was between 5 and 50 mg/L. Intra-particle diffusion and the Boyd relationship showed that arsenic sorption was controlled by the film diffusion mechanism. The Langmuir, Freundlich, and Dubinin-Radushkevitch isotherms were fitted to experimental data, and the Langmuir isotherm presented the best fit. Thermodynamic parameters (Delta G degrees, Delta H degrees, Delta S degrees) showed that the arsenic sorption process was a spontaneous process, endothermic, and produced an increase in entropy. (C) 2012 Elsevier B.V. All rights reserved.