Synthesis and Characterization of a Novel Graft Copolymer Containing Carboxyl Groups and Its Application to Extract Uranium(VI) from Aqueous Media

Abstract

A novel poly(methacrylic acid)-grafted-cellulose/bentonite (Cellu-g-PMAAc/Bent) superabsorbent composite was prepared through graft copolymerization reaction among cellulose, methacrylic acid, and bentonite in the presence of N,N'-methylenebisacrylamide as a crosslinker and potassium peroxydisulphate as an initiator. The structural and morphological characteristics of the graft copolymer were determined using Fourier transform infrared spectra, scanning electron microscope-energy dispersion analysis, and X-ray diffraction. The effectiveness of the Cellu-g-PMAAc/Bent, as adsorbent for the removal and recovery of uranium(VI) from aqueous media, was studied. The effects of pH, contact time, and initial sorbate concentration were studied to optimize the conditions for maximum adsorption. The adsorption process, which was pH dependent, shows maximum removal (>99.0%) at pH 6.0. Kinetic study showed that 180 min of contact at 100 mg/L could adsorb about 99.2% of U(VI) onto Cellu-g-PMAAc/Bent. A pseudosecond-order kinetic model successfully described the kinetics of sorption of U(VI). Adsorption equilibrium data were correlated with the Langmuir, Freundlich, and Redlich-Peterson isotherm models. The best fit was obtained with Freundlich model. Desorption of U(UI) was studied by using 0.1M HCl. Adsorption/desorption for more than six cycles showed the possibility of repeated use of this graft copolymer for the recovery of U(VI) from aqueous solutions. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 122: 874-884, 2011