Complex dielectric permittivity of metal and polymer modified montmorillonite

Ya Chu; Shaokai Nie; Songyu Liu; Changho Lee; Bate Bate

doi:10.1016/j.jhazmat.2019.04.066

Complex dielectric permittivity of metal and polymer modified montmorillonite

J Hazard Mater. 2019 Jul 15:374:382-391. doi: 10.1016/j.jhazmat.2019.04.066. Epub 2019 Apr 22.

Authors

Ya Chu¹, Shaokai Nie¹, Songyu Liu¹, Changho Lee¹, Bate Bate²

Affiliations

¹ Institute of Geotechnical Engineering, College of Civil Engineering and Architecture, Zhejiang University, 866 Yuhangtang Road, Hangzhou, 310058, China.
² Institute of Geotechnical Engineering, College of Civil Engineering and Architecture, Zhejiang University, 866 Yuhangtang Road, Hangzhou, 310058, China. Electronic address: batebate@zju.edu.cn.

PMID: 31028917
DOI: 10.1016/j.jhazmat.2019.04.066

Abstract

Owing to its high surface area and high surface charge density, clay, either contaminated with heavy metal ions or modified with organic additives as barrier materials, is difficult to assess and monitor. Complex dielectric permittivity (κ*) showed promising potential in tackling the above issues. In this study, the complex dielectric permittivity (κ*) of clays modified with a surfactant, four polymers, and four metal ions was measured at frequencies from 0.2-20 GHz. With the addition of polymer and metal ions, increasing frequency caused a slight decrement in real permittivity but a significant decrement in effective permittivity. A modified linearity polynomial equation, which considered the particle conductivity, was developed to fit the relationship between effective conductivity (σeff) and porosity ranging from 0.7 to 1.0. A three-dimensional Cole-Cole plot (κ'-κeff″-w) shows Cole-Cole circle expansion at higher water content. The resonance strength of modified clays was observed to increase with water content, which suggests that the number of water molecules in the diffuse layer of polymer or metal ions saturated clay increased. However, sorbed polymer and metal ions have an insignificant influence on the resonance time τ_s and stretching exponent 1-α. κ* can provide nondestructive characterization of metal or polymer modified clays.

Keywords: Complex dielectric permittivity; Effective conductivity; Metal; Modified clay; Polymer; Resonance time.