Enhanced degradation of 2,4-DCP in a bicarbonate-modified Fenton system with EDTA under near-neutral conditions

Introduction of EDTA to form Fe Ⅱ -EDTA enhanced 2,4-DCP degradation in Fenton system modified by bicarbonate under near-neutral condition. • Bicarbonate-Modified Fenton was successfully applied for 2,4-DCP degradation under near-neutral conditions. • EDTA was introduced to effectively reduce the dosage of Fe 2+ and NaHCO 3 . • ·OH, followed by O 2 · − and 1 O 2 were the main ROSs in the oxidation process. To address the issues of low pH requirements and low active iron content in the traditional Fenton system, bicarbonate in this study was presented in Fenton system to form HCO 4 − through reaction with hydrogen peroxide (HCO 3 – –H 2 O 2 , BAP) and activated by Fe Ⅱ -EDTA to enhance the degradation of 2,4-DCP under near-neutral conditions. 2,4-DCP can be totally degraded after 60 min of reaction at pH of approximately 6.4 under the optimal concentrations of Fe 2+ , NaHCO 3 and EDTA-2Na of 4 mmol·L −1 , 10 mmol·L −1 and 2 mmol·L −1 , respectively. In addition to serving as a reactant in the reaction between bicarbonate and hydrogen peroxide to form the intermediate HCO 4 − , bicarbonate also functions as a pH buffer to bring the solution's pH closer to neutral. The introduction of EDTA-2Na can effectively inhibit iron precipitation to promote maintaining the existence of Fe in dissolved form, improving the catalytic capacity of the system and reduce the dosage of Fe 2+ . The primary involvement of ·OH in the reaction process was validated by free radical quenching studies and EPR testing; the contributions of 1 O 2 and O 2 · − were very small.