Synthesis and characterization of cellulose based adsorbents for removal of Ni(II), Cu(II) and Pb(II) ions from aqueous solutions

Functional copolymers were prepared by graft polymerization of the cellulose extracted from agricultural residue rice husk thus represent a class of highly efficient, eco-friendly and biodegradable adsorbents for water purification applications. Functionalized grafted copolymers of cellulose with N-isopropylacrylamide (NIPAM) and comonomer acrylic acid (AAc) were synthesized by free radical grafting. To ascertain the grafting, cellulose and its graft copolymers were analyzed through various characterizations techniques such as FESEM, XRD, FTIR, TGA/DTA/DTG and swelling properties. Sorption of Ni(II), Cu(II) and Pb(II) metal ions was studied as a function of time, temperature, pH and concentration of metal ions in solution. The order for metal ions uptake was Cell-g-NIPAM-co-AAc > Cell-g-NIPAM > ungrafted cellulose. The metal ions sorption was best fitted in the pseudo second-order kinetic model and Langmuir adsorption isotherm model. At the optimized conditions, almost complete sorption of Pb(II) ions was observed for Cell-g-NIPAM-co-AAc copolymer, whereas 74.5% of Ni(II) and 77.5% of the Cu(II) metal ions were sorbed by Cell-g-NIPAM-co-AAc copolymer.