An investigation into the adsorption of thorium(IV) from aqueous solutions by a carboxylate-functionalised graft copolymer derived from titanium dioxide-densified cellulose

The use of a carboxylate-functionalized graft copolymer (PGTDC-COOH) based on titanium dioxide-densified cellulose (TDC) for the removal and recovery of thorium(IV) [Th(IV)] from industrial waste-water is reported in this paper. Infrared spectroscopy and X-ray diffractometer were used to characterize the adsorbent material. Batch equilibrium experiments showed that the adsorbent exhibited 98.6 +/- 3.1% adsorption from an initial concentration of 10 mg/L Th(IV) solution at pH 5.0. The sorption kinetics have been analysed by pseudo-first-order and pseudo-second-order kinetic models and the adsorption kinetics was described by pseudo-second-order model. The experimental data obeyed Langmuir isotherm and the maximum monolayer adsorption capacity for Th(IV) was also found to be 92.23 +/- 2.4 mg/g at 30 degrees C. The desorption capacity of HCl concentrations of different strengths ranging from 0.001 to 0.1 M was also studied. Maximum desorption of 98.2 +/- 2.8% for Th(IV) occurred with 0.1 M HCl. The adsorption efficiency towards Th(IV) ion removal was tested using artificial sea water. Almost complete removal was possible with 3.5 g of the adsorbent from 1 L of the sea water. (C) 2012 Elsevier Ltd. All rights reserved.