Highly efficient capture of uranium from seawater by layered double hydroxide composite with benzamidoxime

Hui Wang; Huiqin Yao; Lihong Chen; Zihuan Yu; Lixiao Yang; Cheng Li; Keren Shi; Cuiqing Li; Shulan Ma

doi:10.1016/j.scitotenv.2020.143483

Highly efficient capture of uranium from seawater by layered double hydroxide composite with benzamidoxime

Sci Total Environ. 2021 Mar 10:759:143483. doi: 10.1016/j.scitotenv.2020.143483. Epub 2020 Nov 10.

Authors

Hui Wang¹, Huiqin Yao², Lihong Chen¹, Zihuan Yu¹, Lixiao Yang¹, Cheng Li³, Keren Shi⁴, Cuiqing Li⁵, Shulan Ma⁶

Affiliations

¹ Beijing Key Laboratory of Energy Conversion and Storage Materials, College of Chemistry, Beijing Normal University, Beijing 100875, China.
² School of Basic Medical Sciences, Ningxia Medical University, Yinchuan 750004, China.
³ Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China.
⁴ State Key Laboratory of High-efficiency Utilization of Coal and Green Chemical Engineering, Ningxia University, Yinchuan 750021, China.
⁵ Department of Chemical Engineering, Beijing Institute of Petrochemical Technology, Beijing 102617, China.
⁶ Beijing Key Laboratory of Energy Conversion and Storage Materials, College of Chemistry, Beijing Normal University, Beijing 100875, China. Electronic address: mashulan@bnu.edu.cn.

PMID: 33229092
DOI: 10.1016/j.scitotenv.2020.143483

Abstract

Through swelling/restoration reaction, benzamidoxime (BAO) is introduced into MgAl-LDH interlayers to assemble a new composite of MgAl-BAO-LDH (abbr. BAO-LDH). Wet samples of the BAO-LDH obtained by washing with diverse solvents are present in colloidal state, which facilitates the fabrication of thin film adsorbents convenient for actual application. After drying, the assembled sample exhibits floral morphology composed of thin nanosheets, much different from hexagonal morphology of NO₃^- intercalated MgAl-LDH precursor (NO₃-LDH), demonstrating a phenomenon rarely found in swelling/restoration. The BAO-LDH depicts an extremely large maximum sorption capacity (q_m^U) of 327 mg·g^-1 and ultra-high selectivity for U. At low U concentrations (5-10 ppm), nearly complete capture (~100%) is achieved in a wide pH range of 3-11, while at high U concentrations (110 ppm), quite high U removals (≥93.0%) are obtained at pH = 6-8, meaning perfect suitability for trapping U from seawater. For natural seawater containing trace amounts of U (3.93 ppb) coexisting with high concentration of competitive ions, the BAO-LDH displays significantly high U removal (87%). Complexation between interlayer BAO (N and O as ligands) with UO₂²⁺ and synergistic interactions of LDH layer hydroxyls with UO₂²⁺ contribute to the highly effective uranium capture. All results demonstrate the BAO-LDH is a promising adsorbent applied in seawater uranium extraction and nuclear wastewater disposal.

Keywords: Adsorption; Benzamidoxime; LDH composite; Seawater; U(VI) extraction.