Removal of Cu 2+ and Pb 2+ Ions Using CMC Based Thermoresponsive Nanocomposite Hydrogel

Abstract

In this study, carboxymethylcellulose (CMC) based thermoresponsive nanocomposite hydrogel was synthesized for the removal of Cu 2+ and Pb 2+ ions from aqueous solutions. To prepare nanocomposite hydrogel, graft copolymerization of N-isopropyl acrylamide (NIPAm) and acrylic acid (AA) onto CMC was carried out in Na-montmorillonite (MMT)/water suspension media and ammonium persulfate (APS) used as initiator. The chemical structures of hydrogels were characterized by Fourier transform infrared (FT-IR) and X-ray diffraction spectroscopy (XRD). Lower critical solution temperature (LCST), pH responsivity, swelling, and deswelling properties of the hydrogels were also examined. In addition competitive and non-competitive removal of Cu 2+ and Pb 2+ studies were carried out. According to heavy metal sorption studies results, removal capacities of nanocomposite hydrogel for both metal ions were found to be higher than those of pure hydrogel. The analyzed adsorption data showed that the adsorption process of Cu 2+ and Pb 2+ could be explained by pseudo-second order kinetic model. Moreover, according to competitive sorption studies, it is found to be that both hydrogels are more selective to Cu 2+ ion rather than Pb 2+. A carboxymethylcellulose-g-poly(NIPAm-co-AA)/MMT hydrogel was synthesized and the potential use as a Cu 2+ and Pb 2+ adsorbent from aqueous solutions was studied. It could be shown that both hydrogels adsorb relatively high amounts of metal ions in 48h and the presence of MMT in the hydrogel nanocomposite causes a slight increase in the sorption capacity compared to the pure hydrogel. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.