Study On The Electrokinetic Remediation Of Heavy Metal Contaminated Soils

Electrokinetic remediation is an emerging in situ technology developed to remove heavy metals contaminants from fine-grained soils. The soil surface is with negative charge, so the cations are adsorded on the soil surface to be the charged double lay. When a direct current electric field is applied across the soil, an electro-kinetic phenomenon is occurred. Electro-osmosis, electro-migration and electrophoresis are the main mechanisms. In this paper, the transport mechanisms of the contaminants are presented, it will help to know the contaminant transport rules through the clay and give a guide to choose the appropriate parameters.Direct current electric fields have been applied in several geotechnical and geoenvironmental engineering applications, including electro-osmotic dewatering and consolidation, ion injection and contaminant removal. Such applications cause electrochemical effects in soil, leading to changes in the soil's physical, chemical and mechanical properties. The paper evaluated the coupled electro-chemico-mechanical effects of DC fields on soft soils. The analysis shows that there is a direct effect of electrolysis, transport and geochemical changes on the soil mechanical properties.These two mechanisms, electroosmosis and ionic migration, are the primary driving driving forces to remove contaminants from soil pores during the electrokinetic extraction process. Many electrochemical reactions and soil-contaminant interactions, such as electrolytic decomposition of water, sorption and desorption of contaminants onto and from the clay particle surface, and reversal of zeta potential on the clay particle surface, occur simultaneously. These reactions and interaction may enhance of retard the efficiency of the cleanup process, but these are not fully understood. So the further experimental study and theoretical formulations are needed to develop the process. This paper presents the design, fabrication, and assembly of a new apparatus for apparatus for electrokinetic remediation studies, specifically made to experimentally study on zinc ions transport in clay under DC fields, and the concentration, water content and pH of the sampleclay are measured respectively. The results show that electrokinetic remediation can effectively remove zinc ions through the clay.