A method for evaluating corrosion of contaminated soil—Electrochemical Impedance Spectroscopy (EIS) method

Abstract

In this study, the equations for electrochemical impedance characteristics, including Nyquist diagrams and Bode chart, of contaminated soils was obtained by using soil mechanics, chemical, electrochemical and microscopic analysis. The analysis is implemented in light of the relationship between mineral composition, microstructure, macro-performance and electrochemical characteristics of contaminated soil. The parameters for physical, mechanical and electrochemical properties were then obtained based on the EIS characteristic. By theoretical EIS analysis, the relationship between electrochemical properties (electrolyte resistance, charge transfer resistance, electric double layer capacitor and diffusion resistance coefficient) and soil properties (the mineral compositions, moisture, soil microstructure, pore distribution and soil strength) was determined. As a result, the equivalent circuit model and corrosion evaluation system for the contaminated soil were established, which can evaluate the soil contaminations and provide advices on electric double layer, electrode material, solid electrolyte and corrosion protections of metallic materials embedded in the soils. It also provides important engineering data and scientific basis for evaluation of ecological suitability, which has significant economic and social benefits.