Effective capture of aqueous uranium from saline lake with magnesium-based binary and ternary layered double hydroxides

• Published in: The Science of the total environment 2019-08, Vol.677, p.556-563
• Main Authors: Tu, Jingwei, Peng, Xiaoqian, Wang, Shuting, Tian, Chen, Deng, Hong, Dang, Zhi, Lu, Guining, Shi, Zhenqing, Lin, Zhang
• Format: Article
• Language: English
• Subjects: Layered double hydroxide; Saline lake; Surface complexation; Uranium
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2019.04.429

Uranium in saline lake brine is a nuclear resource that attracts worldwide attention. Relatively low concentrations (about 0.2 mg L−1 to 30 mg L−1) require high affinity for the capture materials. In this paper, magnesium binary layered double hydroxides (MgAl-LDH) and its Fe-induced ternary LDH (MgAlFe-LDH) were synthesized for the extraction of simulated concentrations of U(VI) in the saline lake brine system. Batch experiments have shown that both LDHs have strong affinity towards uranium. MgAl-LDH yielded of stronger affinity in lower U(VI) concentrations (0.2 mg L−1 to 5 mg L−1), while MgAlFe-LDH was at higher U(VI) concentrations (5 mg L−1 to 30 mg L−1). For current uranium extraction, the affinities of MgAl-LDH and MgAlFe-LDH are more than twice the maximum affinity of other LDHs and LDHs-based materials. Therefore, these two LDHs are suitable for U(VI) extraction with different concentration levels in saline lakes. The capture process followed the pseudo-second-order kinetics with fast adsorption speed, and the coexisting cations have little effect on the extraction rate. Research through X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) showed the main adsorption mechanisms are surface complexation and the interlayer carbonate coprecipitation. This work provides a potential method for U(VI) extraction while reusing the waste magnesium resources in saline lake. [Display omitted] •Magnesium binary and ternary LDHs were prepared by co-precipitation method.•The LDHs show strong affinity to low concentration of uranium in saline lake.•Coexisting cations have little influence on the extraction of uranium.•The capture mechanisms are surface complexation and coprecipitation.