Grafting of cellulose with N-isopropylacrylamide and glycidyl methacrylate for efficient removal of Ni(II), Cu(II) and Pd(II) ions from aqueous solution

Abstract

In this work, Cell-g-NIPAM-co-GMA graft copolymer was synthesized by potassium persulfate (KPS) initiated free radical polymerization of the N-isopropylacrylamide (NIPAM) and glycidyl methacrylate (GMA) onto cellulose extracted from agro waste rice husk. Comparative characterization of the ungrafted and grafted cellulose through techniques such as FESEM, XRD, FTIR, and thermogravimetry confirmed the grafting of the monomers onto the hydroxy groups of the cellulose backbone. Effects of the contact time and pH of the medium were also analyzed in order to evaluate the water uptake and swelling properties of the ungrafted and grafted copolymer. The metal ion sorption applications of the Cell-g-NIPAM-co-GMA graft copolymer were studied for Ni(II), Cu(II) and Pd(II) ions from aqueous solution. Maximum percent uptake of Ni(II) and Pb(II) metal ions was reported at 6.0 pH whereas, for Cu(II) metal ion, the optimized pH was 5.0 at the optimized temperature of 30 °C and after a contact time of 6 h. The adsorption data were also analyzed through different kinetic and adsorption isotherm models. Pseudo-second-order kinetic model and Langmuir adsorption isotherm better described the adsorption of metal ions onto grafted copolymer. The qmax as calculated from Langmuir adsorption isotherm model were 74.68, 82.92 and 119.76 mg.g−1, respectively for Ni(II), Cu(II) and Pb(II) metal ions.