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Adsorption behavior of U(VI)/Th(IV) by acid-leached red mud: A comparative study |
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| Authors: | Liu Zhirong Xiong Huanjia Zhou Shaoqi |
| Affiliation: | 127. Key Laboratory of Nuclear Resources and Environment, East China Institute of Technology, Ministry of Education, Jiangxi, 330013, P. R. China 227. Department of Applied Chemistry, East China Institute of Technology, Jiangxi, 344000, P. R. China 327. College of Environmental Science and Engineering, South China University of Technology, Guangdong, 510006, P. R. China 427. State Key Laboratory of Subtropical Building Science, South China University of Technology, Guangdong, 510641, P. R. China 527. Key Laboratory of Environmental Protection and Eco-remediation of Guangdong Regular Higher Education Institutions, South China University of Technology, Guangdong, 510006, P. R. China |
| Abstract: | Acid-leached red mud, a type of inorganic-adsorptive by-product of bauxite Bayer process via acid leaching, was used for the removal of U(VI)/Th(IV) from aqueous solutions. Variables of the adsorption such as contact time, temperature, solution pH, initial concentration and dose of acid-leached red mud were investigated. The results indicated that the adsorption is strongly affected by dosage, the solution pH, contact time and initial concentration. The isothermal data were fitted with both Langmuir and Freundlich equations, but the data fitted the former better than the latter. A pseudo-first-order kinetic model and pseudo-second-order kinetic model were used to describe the kinetic data, but the pseudo-second-order kinetic model was the better. Thermodynamic parameters such as enthalpy (ΔH ○ ), entropy (ΔS ○ ) and free energy change (ΔG ○ ) were calculated, and the negative ΔG ○ values of U(VI)/Th(IV) at different temperatures confirmed the adsorption processes were spontaneous. |
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