Sorption properties of chelating polymer-clay nano-composite resin based on iminodiacetic acid and montmorillonite: water absorbency, metal ion uptake, selectivity, and kinetics

BACKGROUNDThis paper presents the study of the sorption performance of a novel poly[N-(4-vinylbenzyl)-iminodiacetic acid)-montmorillonite nano-composite. The composite was obtained through in situ polymerization of the previously synthesized monomer N-(4-vinylbenzyl)-iminodiacetic acid in the presence of organic-modified montmorillonite and N,N-methylene-bis-acrylamide. RESULTSThe water uptake of the nanocomposites increased with increasing montmorillonite content. Metal ion retention studies as a function of montmorillonite content showed an unexpected trend in which the adsorption capacities decreased as the montmorillonite content increased. Selectivity experiments reveals that composites present a certain selectivity towards Cu2+ and that montmorillonite content does not provide selectivity to the composite. Kinetic experiments were conducted using a Cu2+ aqueous solution at pH 5.0 and it was observed that after 60min contact the maximum retention is reached. Kinetics and diffusion models reveal that the metal ion retention occurs mainly at the surface of resin particles, suggesting a film diffusion process. CONCLUSIONThe nano-composite showed the ability to remove metal ions. The process can be described by a Langmuir isotherm, whereas kinetic studies indicated that the pseudo-second-order model could describe the sorption process. The intra-particle diffusion model suggests that sorption mechanism is film diffusion. (c) 2013 Society of Chemical Industry