A cost-effective Electro-Fenton process with graphite felt electrode aeration for degradation of dimethyl phthalate: Enhanced generation of H₂O₂ and iron recycling that simultaneously regenerates the electrode

A graphite felt electrode with electrode aeration (GF-EA) was used for the Electro-Fenton treatment of dimethyl phthalate (DMP) wastewater. At pH 3.0, removal efficiencies of 200 mg/L DMP and solution TOC by EA were 50.0% and 55.4% higher than solution aeration (SA), respectively. At pH 4.0 and 5.5, EA showed 36.4–56.1% and 9.4–35.7% higher removal for 20–50 mg/L DMP and TOC than SA, respectively. High effective degradation performance of EA was attributed to the enhanced mass transfer of O₂ and the solution, which provided the sufficient active area for H₂O₂ electro-generation and promoted the Fe³⁺/Fe²⁺ cycling, thus increasing the [rad]OH content. Using EA, GF could collect iron sludge at low O₂ flux, and then strip it for reuse at large air flux. This process regenerated GF electrode and elided the disposal of iron sludge. By supplementing one-fifth of the original FeSO₄ dosage, the operation costs of the iron-sludge-stripping EA system were 35% and 27% of those in SA system for the same removal of 200 mg/L and 20 mg/L DMP, respectively. During long-term use, DMP degradation performance of EA gradually improved due to the increased hydrophilic property and oxygen-containing functional groups, while the decreased DMP removal with SA was ascribed to the electrode poisoning caused by iron sludge deposition.