A new two-dimensional experimental apparatus for electrochemical remediation processes

Abstract

Electrochemical extraction of contaminants from soils is a promising soil decontamination technology. Various experiments have been conducted to study electrochemical reactions and geochemical processes in the electrochemical extraction using different experimental apparatuses. This paper presents the development of a new closed two-dimensional (2D) apparatus that can better simulate the field application of the technology and accurately monitor the most important electrochemical parameters to understand the process. The innovative features of the new apparatus include the outer and inner electrodes designed to apply a non-uniform electrical field across the specimen as in the field electrochemical remediation process, the probes installed to measure the 2D distribution of electrical voltage, and the gas and fluid volume measurement devices used to accurately monitor the gas generation and electroosmotic flow rates at both electrodes as a function of time. The components of this new apparatus and the features of each component are described. The operating procedure and some typical results from three experiments with the apparatus are demonstrated. The results show that the variation of the gas generation rate is in good agreement with the electric current. Their relation provides a valid evaluation for electrochemical behavior of the system and Faraday's laws of electrolysis. The 2D profiles of cadmium concentration and voltage distribution at the end of the experiment reveal the great effects of a non-uniform electrical field on the contaminant mobilization.