The operation characteristics and electrochemical reactions of a specific circulation-enhanced electrokinetics

For electrokinetics remediation, the acid produced at the anode due to the water electrolysis will cause the soil acidification and destroy the soil constituents. Especially, the contaminated soils in Taiwan are usually agricultural lands; it is necessary to improve the performance of EK system to maintain the soils nature after remediation. In this study, a circulation-enhanced EK system (CEEK) was designed to neutralize the pH of the working solution and soils. Experiments were conducted by the control of different electrolyte species (sodium and potassium salts) and concentrations (10−3 to 5 × 10−2 M), respectively. Experimental results show the operational characteristics include: the CEEK system can effectively stabilize the pH of processing solution at neutral range and the current can be maintained at stable status with carbonate salts; the pH buffering range of working solution in the CEEK system depends on the electrolyte species and their concentration significantly; the water content remains roughly as their original nature in the CEEK system. For consideration of electrochemical reactions, the water electrolysis is the predominating electrochemical reaction in the CEEK system, which not only influences the pH but also the conductivity of the working solution. In the application of practical engineering, there exist linear relationships between the pH, conductivity, current and the electrolyte concentration, respectively, which can serve as a means to assist engineers to select operational parameters of CEEK.