Functionalized cellulose with hydroxyethyl methacrylate and glycidyl methacrylate for metal ions and dye adsorption applications

Abstract

Biodegradable functionalized cellulose based graft copolymers, Cell-g-HEMA and Cell-g-HEMA-co-GMA have been synthesized through free radical polymerization. The graft copolymers are used as sorbents for the removal of Ni(II), Cu(II) and Pb(II) ions, cationic (malachite green, crystal violet) and anionic (congo red) dyes as a function of adsorption time, temperature, pH of medium and concentration of metal ions and dyes. The sorption capacities of polymeric adsorbents for all the adsorbates decrease in the order Cell-g-HEMA-co-GMA > Cell-g-HEMA > Pure cellulose. Cell-g-HEMA-co-GMA removes 81.4%, 71.6% and 75.5% of the Ni(II), Cu(II) and Pb(II) ions respectively from their aqueous solutions and shows maximum q_m of 93.55, 90.91 and 92.59 mg/g for Ni(II), Cu(II) and Pb(II) ions respectively. The percent dye uptake capacities are reported 49.42%, 67.74%, and 70.38% for malachite green, crystal violet and congo red dyes, respectively by Cell-g-HEMA-co-GMA. The metal ion and the dye sorption data are best fitted in the pseudo-second-order kinetic model and Langmuir adsorption isotherm model. Before adsorption studies grafting reaction conditions of HEMA and GMA onto cellulose were optimized. FTIR, XRD, SEM and TGA/DTA characterization techniques were ascertained to describe the structural aspects of graft copolymers. Swelling properties of graft copolymers were studied at different pH conditions.

Keywords: Cellulose; Dye adsorption; Metal ion sorption.