Adsorption of uranium (Ⅵ) by activated carbon from radioactive wastewater
YU Jing1,2, WANG Jianlong1,3, JIANG Yizhou2
1. Collaborative Innovation Center for Advanced Nuclear Energy Technology, Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084, China;
2. Northwest Institute of Nuclear Technology, Xi'an 710024, China;
3. Beijing Key Laboratory of Radioactive Waste Treatment, Tsinghua University, Beijing 100084, China
Abstract：The adsorption of uranium from wastewater onto activated carbon was investigated in batch experiments. Four independent variables, the contact time, solution pHa, initial uranium concentration and temperature, were varied to determine the influence of these parameters on the adsorption of the uranium from water. The activated carbon size were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), with the element content characterized by energy dispersive X-ray spectrometer (EDS) and surface functional groups characterized by infrared spectrocopy (FTIR). The FTIR spectra indicated that hydroxyl groups are present on the surface of the activated carbon and affected the adsorption. The U(Ⅵ) adsorption onto activated carbon reached sorption equilibrium within 30 min. The adsorption of U(Ⅵ) on activated carbon was strongly dependent on the pHa in the range of 3.0~9.0. The adsorption capacity and removal percent increase for pHa from 3 to 5, decrease for pHa=5~7, and then increase quickly for pHa=7~9. The U(Ⅵ) adsorption on activated carbon is well described by a pseudo-second-order kinetic model and the Tempkin, Slip, and D-R isotherm models. The sorption reaction is spontaneous, exothermic and increases the entropy. The maxmium adsorption capacity is 62.50 mg·g-1. The maxmium removal rate is 99.23%.
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