Novel E-Peroxone Process with Tandem Flow-Through Configuration: In Situ O2 Supplement and Efficient Ozone Utilization

A novel E-peroxone process with tandem flow-through (TFT) configuration was developed in this work, and its efficacy was verified via the degradation of recalcitrant compounds, i.e., dyes and poly(vinyl alcohol) (PVA). The gas diffusion electrode (GDE) made of carbon fiber was employed as the cathode, while the anode of ruthenium–iridium acted as a dimensionally stable anode (DSA). The system achieved oxygen self-sufficiency through an innovative oxygen transfer mode, avoiding the need for an additional oxygen supply. The electrodes with TFT configuration ensured high utilization efficiency of ozone as the peroxone reaction occurred continuously in two adjacent chambers. H₂O₂ yield efficiency was compared between single and TFT E-peroxone processes under various conditions, including flow rates, current densities, and pH values. Under optimal H₂O₂ production conditions, the TFT E-peroxone process could remove 85.5% of dyes and 73.4% of PVA with single-pass, respectively. Electron paramagnetic resonance (EPR) tests and quenching experiments revealed that hydroxyl radicals (^•OH) and carbon radicals are the primary active species. Hydroxyl radicals played a major role in the single and TFT E-peroxone processes. This study demonstrates that the TFT E-peroxone process holds great promise as an advanced technology for efficient wastewater treatment.