The ability of ordered mesoporous carbon CMK-3 has been explored for the removal and recovery of uraium from aqueous solutions. The textural properties of CMK-3 were characterized using small-angle X-ray diffraction and N2 adsorption–desorption, and the BET specific surface area, pore volume and the pore size were 1143.7 m2/g, 1.10 cm3/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 uranium sorption capacity at initial pH of 6.0 and contact time of 35 min. Adsorption kinetics was better described by the pseudo-second-order model and adsorption process could be well defined by the Langmuir and Freundlich isotherm. The thermodynamic parameters, ∆G°(298 K), ∆H° and ∆S° were determined to be −7.7, 21.5 k J mol−1 and 98.2 J mol−1 K−1, respectively, which demonstrated the sorption process of CMK-3 towards U(VI) was feasible, spontaneous and endothermic in nature. The adsorbed CMK-3 could be effectively regenerated by 0.05 mol/L HCl solution for the removal and recovery of U(VI). Complete removal (99.9 %) of U(VI) from 1.0 L industry wastewater containing 15.0 mg U(VI) ions was possible with 2.0 g CMK-3.
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This work is financially supported by the National Natural Science Foundation of China (Grant No. 21101024), Key Project of Chinese Ministry of Education (Grant No. 211086), Natural Science Foundation of Jiangxi Province (No. 2010GQH0015), Sci. & Tech. Project of Jiangxi Provincial department of education (No. GJJ11139), Open Project Foundation of the Key Laboratory of Radioactive Geology and Exploration Technology Fundamental Science for National Defense (East China Institute of Technology) (2010RGET08), Open Project Foundation of the Engineering Research Center of Nano-Geomaterials of Ministry of Education (China University of Geosciences) (CUGNGM201205), and Open Project Foundation of the State Key Laboratory of Biogeology and Environmental Geology (China University of Geosciences) (BGEG201105).