Preparation of methacrylamide-functionalized crosslinked chitosan by free radical polymerization for the removal of lead ions

Abstract

A new poly(methacrylamide) grafted crosslinked chitosan was prepared for removal of lead, Pb(II) ion from aqueous solution. Crosslinked chitosan, in beads form, was grafted with methacrylamide (MAm) using ammonium persulfate (APS) as free radical initiator. Evidence of grafting was determined by comparing FTIR, TGA, SEM and 13C NMR analyses of chitosan and graft copolymer. The optimal conditions for grafting reaction were as follow: crosslinked chitosan beads (1 g), MAm (17.62 × 10−1 M), APS (2.63 × 10−1 M), reaction time (3 h) and temperature (60 °C). The modified chitosan bead was then used in laboratory batch experiments to evaluate the removal of Pb(II) ion from water samples. The Langmuir and Freundlich adsorption models were also applied to describe the equilibrium isotherms. The results revealed that the adsorption of Pb(II) ions onto the beads fitted very well with the Langmuir model with the maximum capacity (qmax) of 250 mg g−1.