Quantifying the origin of membrane polarization

Abstract

SUMMARY There has been substantial interest in applying induced polarization phenomena, which broadly include electrode and membrane polarization, to characterize organic contamination and biogeochemical environments. Several phenomenological models, semi-quantitative models and models for particular pore shapes have been proposed for understanding membrane polarization. Here, we present a theoretical framework that directly relates membrane polarization to intrinsic statistical properties of porous materials through a two-point correlation function of fixed charges in the pore space. Our framework provides a new way of modelling complex pore structures with a few statistical parameters and quantifies how two distinct physical processes drive complex conductivity response in the absence of conducting grains. One process is a coupling of the static inhomogeneous conductivity to the induced oscillatory electric field, whereas the second process is a coupling of the static electric field to the induced conductivity modulation. Including both effects, we quantitatively predict the frequency-dependent membrane polarization and show excellent agreement between our predictions and experiments in model porous materials.