Remediation characteristics and effects of electrokinetic-citric acid system on karst soil contaminated by arsenic and cadmium

Abstract

The features and method of citric acid's remediation on arsenic and cadmium-contaminated soil under electrification were investigated by modeling arsenic and cadmium-contaminated soil in karst areas. According to the experimental findings, arsenic and cadmium in soil dissolve more effectively at higher citric acid concentrations. After being electrified, it can encourage the citric acid system, which breaks down cadmium and arsenic in soil. In soil, oxidizable and acid extractable arsenic are removed at rates of 89.19 % and 48.97 %, respectively, and oxidizable and acid extractable cadmium are removed at rates of 60.88 % and 87.87 %. Alkaline circumstances are also favorable for the desorption and migration of arsenic in karst environments; high calcium conditions, however, will inhibit the dissolution of arsenic while favoring the dissolution of cadmium. The morphological alterations of heavy metals during the electro-enhanced remediation process were examined using Visual MINTEQ software. The findings demonstrated that throughout the process, cadmium predominately existed in the forms of Cd2+ and Cd-Citrate-, whereas arsenic predominately existed in the forms of H2AsO4- and H3AsO4 in acidic environment and HAsO42- and H2AsO4- in alkaline conditions. In summary, electric citric acid plays a crucial role in removing cadmium and arsenic pollution in karst soil, which is of great significance for the remediation of soil contaminated by cadmium and arsenic compounds in karst environments.