Strengthened erosion resistance of compacted bentonite by layered double hydroxide: A new electrostatic interaction-based approach

Zhen Zhang; Pengyuan Gao; Gilles Montavon; Zongyuan Chen; Dongqi Wang; Zhaoyi Tan; Qiang Jin; Wangsuo Wu; Ju Wang; Zhijun Guo

doi:10.1016/j.chemosphere.2021.133402

Strengthened erosion resistance of compacted bentonite by layered double hydroxide: A new electrostatic interaction-based approach

Chemosphere. 2022 Apr:292:133402. doi: 10.1016/j.chemosphere.2021.133402. Epub 2021 Dec 22.

Authors

Zhen Zhang¹, Pengyuan Gao¹, Gilles Montavon², Zongyuan Chen³, Dongqi Wang⁴, Zhaoyi Tan⁵, Qiang Jin¹, Wangsuo Wu¹, Ju Wang⁶, Zhijun Guo⁷

Affiliations

¹ Frontiers Science Center for Rare Isotopes, Lanzhou University, Lanzhou, 730000, China; Radiochemistry Lab, School of Nuclear Science and Technology, Lanzhou University, Lanzhou, 730000, China.
² Subatech, UMR6457, IN2P3/CNRS/IMT Atlantique/Université de Nantes, 4 Rue Alfred Kastler, F-44307, Nantes, France.
³ Frontiers Science Center for Rare Isotopes, Lanzhou University, Lanzhou, 730000, China; Radiochemistry Lab, School of Nuclear Science and Technology, Lanzhou University, Lanzhou, 730000, China. Electronic address: zychen@lzu.edu.cn.
⁴ School of Chemical Engineering, Dalian University of Technology, Dalian, 100049, China.
⁵ Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang, 621900, China. Electronic address: tanzhaoyi@caep.cn.
⁶ Beijing Research Institute of Uranium Geology, 10, Xiao-Guan-Dong-Li, Beijing, 100029, China.
⁷ Frontiers Science Center for Rare Isotopes, Lanzhou University, Lanzhou, 730000, China; Radiochemistry Lab, School of Nuclear Science and Technology, Lanzhou University, Lanzhou, 730000, China. Electronic address: guozhj@lzu.edu.cn.

PMID: 34953877
DOI: 10.1016/j.chemosphere.2021.133402

Abstract

For the geological repository of high-level radioactive waste (HLW) built in granitic host rock，the control of buffer material (compacted bentonite) erosion and subsequent loss caused by groundwater in granite fissures is an unresolved problem of major concern. We propose here new insight into enhancing the erosion resistance of compacted bentonite by means of its electrostatic interaction with oppositely-charged layered double hydroxide (LDH). The interaction between bentonite and LDH was studied by dropwise addition of colloidal LDH into colloidal bentonite suspension, during which the variation in electrical conductivity, zeta potential and particle size proved a strong interaction between these two materials. Interestingly, in addition to their aggregation, intercalated structures of LDH and montmorillonite were found in the composite (BEN@LDH) by a combined characterization of X-ray diffraction (XRD) and high resolution transmission electron microscopy (HR-TEM), and were confirmed by density functional theory (DFT) calculation. Colloid generation of compacted BEN@LDH under ultrasonic conditions is negligible comparing with that of compacted bentonite, indicating a significantly higher erosion resistance. Besides, a small amount of LDH by mechanically mixing with bentonite (mass ratio 1:99) can also effectively improve the erosion resistance of compacted bentonite. Moreover, BEN@LDH displayed stronger retention performance towards U(VI) and Se(IV) than bentonite under near-neutral/weakly alkaline conditions. Our results indicate that LDH is a promising additive in compacted bentonite, and this approach may be extended to common geotechnical structures built with clays and soils.

Keywords: Adsorption; Bentonite; DFT calculation; Erosion resistance; Intercalation; LDH.

MeSH terms

Bentonite*
Clay
Hydroxides
Radioactive Waste* / analysis
Static Electricity

Substances

Hydroxides
Radioactive Waste
Bentonite
Clay