Removal of thorium from aqueous solution by ordered mesoporous carbon CMK-3

The ability of ordered mesoporous carbon CMK-3 has been explored for the removal and recovery of thorium from aqueous solutions. The textural properties of CMK-3 were characterized using small-angle X-ray diffraction and N-2 adsorption-desorption, and the BET specific surface area, pore volume and the pore size were 1143.7 m(2)/g, 1.10 cm(3)/g and 3.4 nm. The influences of different experimental parameters such as solution pH, initial concentration, contact time, ionic strength and temperature on adsorption were investigated. The CMK-3 showed the highest thorium sorption capacity at initial pH of 3.0 and contact time of 175 min. Adsorption kinetics was better described by the pseudo-second-order model and adsorption process could be well defined by the Langmuir isotherm. The thermodynamic parameters, a-(3)GA degrees(298 K), a-(3)HA degrees and a-(3)SA degrees were determined to be -0.74 kJ center dot mol(-1), 9.17 kJ center dot mol(-1) and 33.24 J center dot mol(-1)center dot K-1, respectively, which demonstrated the sorption process of CMK-3 towards Th(IV) was feasible, spontaneous and endothermic in nature. The adsorbed CMK-3 could be effectively regenerated by 0.02 mol/L HCl solution for the removal and recovery of Th(IV).