Electrokinetics-magnetic/alkali Composite-modified Biochar for Remediation of Cd-contaminated soil

摘要

[Objectives]This study was conducted to explore the removal performance and mechanism of heavy metal Cd in soil by combining electrokinetic technology and modified biochar.[Methods]The electrokinetics-magnetic/alkali composite-modified biochar method was applied to remediate Cd-contaminated soil.[Results]When remediating the soil for 120 h under electric field strength of 2 V/cm with 0.1 mol/L citric acid as the electrolyte,the current periodically varied with the remediation time.Cd^2+in the soil dissociated and migrated from the soil surface,and the addition of the magnetic/alkali composite-modified biochar in the cathode area affected the hydrolysis balance of heavy metal Cd^2+ions and maintained soil pH in a low range.The exchangeable Cd content at the test sampling points near the cathode area was relatively high,and the organic Cd area was evenly distributed.The average removal rate of Cd in the soil was up to 90.31%.The hexagonal anode device configuration enhanced the electromigration performance and made the soil pH and conductivity change within a certain range,which was beneficial to the migration of Cd2+and improved the removal rate of soil heavy metal Cd.[Conclusions]This study provides a theoretical basis for the treatment of soil heavy metal pollution and the resource utilization of composite-modified biochar.