Synthesis and characterization of a functionalized graft copolymer of densified cellulose for the extraction of uranium(VI) from aqueous solutions

A novel carboxylate functionalized graft copolymer (PGTDC-COOH) based on TiO2-densified cellulose (TDC) was prepared by grafting poly(methacrylic acid) onto TDC in the presence of N,N′-methylenebisacrylamide (MBA) as a cross-linking agent and Mn(IV)–citric acid as an initiator system. Adsorbent was characterized using FTIR, SEM, XRD, TG-DTG, BET-N2 adsorption measurements, Boehm and potentiometric titrations. The adsorption efficiency of PGTDC-COOH for uranium(VI) from aqueous solutions was examined by batch experiments. The optimum pH was found to be 6.0. Kinetic studies show that the uptake was rapid and equilibrium was established in 1 h. The sorption process follows the pseudo-second-order kinetic model. Langmuir analysis showed that the surface of the adsorbent is uniform and homogeneous in respect to sorption and energy. The adsorption equilibrium constant and maximum adsorption capacity were evaluated to be 0.074 L/mg and 99.4 mg/g, respectively. Utility of the adsorbent was tested by removing U(VI) from simulated nuclear industry wastewater. The possibility of metal recovery from spent adsorbent was investigated using HCl solutions with different concentrations and greater than 96.0% recovery was achieved with 0.1 M HCl.