Deciphering anomalous dielectric traits of nanoconfined water and its roles in modeling crystalline swelling of bentonite

• Published in: Acta geotechnica Vol. 20; no. 4; pp. 1571 - 1583
• Main Authors: Dai, Wen-jie, Chen, Yong-gui, Li, Yu-cheng, Ye, Wei-min, Wang, Qiong, Wu, Dong-bei
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.04.2025; Springer Nature B.V
• Subjects: Bentonite; Civil engineering; Complex Fluids and Microfluidics; Density; Dielectric constant; Dielectric properties; Engineering; Foundations; Geoengineering; Geotechnical Engineering & Applied Earth Sciences; High level radioactive wastes; Hydraulics; Hydrogen bonding; Interlayers; Molecular dynamics; Montmorillonite; Montmorillonites; Physical characteristics; Physicochemical processes; Physicochemical properties; Porous materials; Radioactive waste disposal; Radioactive wastes; Research Paper; Simulation; Soft and Granular Matter; Soil Science & Conservation; Solid Mechanics; Swelling; Waste disposal; Water; Water density; Molecular dynamics; Nanoconfinement; Montmorillonite; Dielectric behavior
• ISSN: 1861-1125; 1861-1133
• DOI: 10.1007/s11440-024-02474-x

The physicochemical properties of Na-montmorillonite (Na-Mt) determine the intrinsic behaviors of bentonite, which are of great significance for its application in high-level radioactive waste disposal. The dielectric behavior of water under nanoconfinement has been the subject of numerous conjectures due to the difficulties associated with experimental investigation. Na-Mt is modeled via molecular dynamics (MD) simulations at the nanoscale, and the dielectric responses as a function of the basal spacing and water density are studied. The results showed a heterogeneous dielectric profile of interlayer water and an unexpected local dielectric enhancement closed to Mt surface. The morphological characteristics of dielectric constant ( ε ) was consistent with the layered structure of interlayer water. The hydrogen bonding network was strengthened near the interface, resulting in a local density augmentation and dipolar mobility decline of interlayer water. This anomalous dielectric behavior was mainly derived from the interfacial effect, rather than the physical field in Na-Mt interlayer. Introducing the MD simulations results into crystalline swelling model, and a significant improvement in accuracy was observed. These results provide a clear insight into the dielectric behavior of interlayer water in Na-Mt.