Removal of uranium(VI) from aqueous solutions by CMK-3 and its polymer composite

The ability of PANI-CMK-3 composite (PANI-CMK-3) by in site polymerizing aniline onto the surface of mesoporous carbon (CMK-3) has been explored for the removal and recovery of uranium from aqueous solutions. The results of FUR, SEM, TG/DTA and N2 adsorption-desorption demonstrated that aniline was successfully polymerized onto the inside and outside surface of CMK-3 rather than occupying the mesopore. The U(VI) sorption on PANI-CMK-3 was well fitted to the Langmuir adsorption isothermal and pseudo-second kinetics models. The monolayer maximum capacity of PANI-CMK-3 was improved from 50.12 mg g-1 of CMK-3 to 118.30 mg g-1 at 298K due to the imine and amine groups in PANI. The thermodynamic parameters ( AH, AS and AG) showed the U(VI) adsorption on CMK-3-PANI and CMK-3 were all endothermic and spontaneous in nature. Selective adsorption experiments (co-existing ions, Na', Mg2', Zn2', Mn2', Ni2' and 5r2') show that the selectivity of CMK-3 was enhanced after aniline polymerization. Moreover, the U(VI) adsorbed on the surface of PANI-CMK-3 can be eluated by 1.0 mol L-1 HC1 solution with high desorption rate of 98%. 2013 Elsevier B.V. All rights reserved.