Synthesis of Carboxymethyl Cellulose-Montmorillonite Hydrogel Composite and Studying its Function for Copper Cation Removal from Aqueous Solutions

Abstract

In this study, composite hydrogel was provided based on carboxymethyl cellulose and nano-sized montmorillonite by situ radical polymerization method and evaluated as copper cation adsorbent from aqueous solution. Synthesis of hydrogel composite and the effect of various parameters such as pH of solution, adsorbent dosage, initial concentration of copper cation, presence of lead and cobalt cations in solution and contact time on adsorption capacity of copper were studied through batch experiments. The results of FTIR spectra showed that functional groups like Si-O-Mg, Si-O-Al and –COOH exist in synthesized hydrogel. The results indicated that with pH increasing of initial Cu2+ solution up to 5, the adsorption capacity increased subsequently. The experimental kinetic and equilibrium data had the most conformity with pseudo-second order kinetic model and Langmuir adsorption isotherm. The maximum obtained adsorption capacity were 111, 100 and 83.3 mg/g at 273, 303 and 333K respectively. The results showed that the Cu2+ ion adsorption is favorable, also the standard free Gibbs energy and standard enthalpy indicated a spontaneous and exothermic adsorption process. In competitive adsorption experiments, composite hydrogel tended to adsorb cations with an affinity order of Pb2+>> Cu2+ > Co2+.