Analysis of space–time profiles of the concentrations of contaminants in soil during electrokinetic remediation

Abstract

A new semiempirical method for the mathematical description of the space–time concentration profiles of contaminants in soil during its electrokinetic remediation is proposed. The method is based on approximating the experimental data on the spatiotemporal behavior of the concentration, C = C(D_a, t). The experimental and theoretical C = C(D_a, t) dependences reported in the literature and obtained in our studies were approximated by seventh order polynomials. For example, the space–time concentration profiles of chlorinated hydrocarbon contaminants in unsaturated soils, such as tetrachloroethylene, trichloroethylene and carbon tetrachloride, have been successfully described by a polynomial function with determination coefficients of R² = 0.9941, 0.9988, and 0.9972, respectively. A pilot test setup for studying the electrokinetic remediation of soils contaminated with mercury compounds, with ten sampling sections and replaceable cartridges with ionites, was designed and built. This setup allowed measuring the space–time concentration profile of mercury in soil samples during electrokinetic remediation. This profile obtained was approximated by a seventh order polynomials with a determination coefficient of R² = 0.9929. It is shown that the polynomial approximation of the space–time concentration profiles of contaminants in soil describes the experimental C = C(D_a, t) dependences no worse (sometimes better) than the Poisson–Nernst–Planck model for ionic flow.