Key Factors Controlling Remediation of Organic Pollutants in Synergistic Electric Field CaO2/Fe(II) Fenton-Like Systems

Abstract

Fenton-like systems for pollutant remediation have attracted significant attention in recent years. However, most research has emphasized the role of oxidative species in simulated solutions, with limited consideration of practical conditions. This research investigated key factors controlling the remediation of toluene and dichloromethane in a dynamic column system under electric field conditions. The results indicated that excessive doses of remediation agents significantly reduced remediation efficiency without an electric field. Surplus CaO₂ increased pH and reduced free radical production. While high Fe(II) doses accelerated CaO₂ dissolution, this created flow paths that facilitated preferential pollutant transport. pH regulated Fe(II) performance, with alkaline conditions causing Fe(II) to precipitate, limiting its migration to the reactive remediation zone. Additionally, in the presence of adsorbed-phase humic acid (HA), increased pH generated dissolved-phase HA that transported pollutants away from the reactive remediation zone, further decreasing remediation efficiency. Under the electric field, the high voltage gradient enhanced pollutant degradation, reducing the need for high doses of remediation agents. However, the inhibitory effect of HA on pollutant degradation intensified as more dissolved-phase HA was produced. These findings offer new insights into the regulating mechanisms of key factors in CaO₂-based Fenton-like systems in the presence and absence of an electric field.