A novel electro-Fenton process coupled with sulfite: Enhanced Fe3+ reduction and TOC removal

To promote the reduction of Fe 3+ and improve the mineralization of organic pollutants , a novel electro-Fenton coupled with sulfite (Fe 3+ -EF/sulfite) process was constructed, which was superior to Fe 3+ -EF process in terms of carbamazepine (CBZ) degradation and mineralization with 5.99 times enhancement in degradation rate constant and 15.7 times enhancement on TOC removal. The complexation of Fe 3+ and sulfite prevented the precipitation of Fe 3+ , reduced Fe 3+ to Fe 2+ , and accelerated the iron cycle, so that H 2 O 2 utilization efficiency (0.051 mg TOC mg H2O2 −1 ) was greatly improved and electric energy consumption was greatly reduced (0.081 kWh g −1 TOC). The quenching experiments and EPR test confirmed that the reactive species, such as SO 3 •- , SO 4 •- , • OH, O 2 •- and 1 O 2 were responsible for the degradation of CBZ. This process also expanded the pH application range from 3 to 9 with satisfactory CBZ removal efficiency. This work verified the suitability of the Fe 3+ -EF/sulfite process for different sulfites (sulfite and bisulfite), typical pollutants (atrazine, sulfamethazine, rhodamine B) and real wastewater with 2.1–18.7 folds enhancement in degradation rate. The Fe 3+ -EF/sulfite process can achieve deep mineralization with low cost and simple operation, which has a broad and cost-effective application prospect in removal of refractory organic pollutants.