Electrokinetic migration of self-produced oxidants from different anodes and their degradation of anthracene
The application of electrokinetic in situ chemical oxidation(EK-ISCO)technology has been extensively investigated for the remediation of contaminated soil.To address challenges related to high oxidant loss,exogenous oxidant addition,low migration efficiency,and limited removal efficiency of organic pollutants,it is a promising solution to use anode to generate oxidants and degrade pollutants under a direct-current electric field.In this study,the reaction cell or electrokinetic column tests were conducted for three anodes(BDD,Ti4O7 and RuO2/Ti)with a sodium sulfate electrolyte to evaluate their ability for self-produced oxidants,the migration of oxidants and the removal rules of organic pollutant anthracene in a quartz sand column.The results demonstrated that the persulfates(PS)concentration reached its peak value(105.1 mmol·L-1)under optimal conditions for anode self-produced oxidants:BDD anode,cation exchange membrane,30 mA·cm-2,0.6 mol·L-1 Na2SO4.In the electrokinetic column experiments,PS produced from anode could migrate to cathode under the action of electroosmosis,the PS concentrations in BDD anode treated electrolyte and soild solution reached the highest value of 0.079～4.52 mmol·L-1,while the highest PS concentrations in the Ti4O7 and RuO2/Ti treated electrolytes were only 0.195 mmol·L-1 and 0.211 mmol·L-1,respectively.Along PS migration,they were decomposed into free radicals with strong oxidation potential to efficiently remove anthracene from the soil column.The removal rates of anthracene after BDD anode treatment ranged from 64.8％to 82.5％,and presented a gradual decline from the anode to the cathode,which was consistent with the distribution of PS concentration in the soil column.The research provides a support for the advancement of EK-ISCO technology.
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