Cost-Effective FeIVO2+ Generation for Antibiotics Removal in Electrochlorination of Mariculture Wastewater

Organic decontamination in saline wastewater was limited in the·OH-dominated oxidation processes due to the inevitable emergence of chlorinated byproducts, and the electrochlorination process could degrade the contaminants utilizing the inherent Cl– ions but shared the same problem. To solve this problem, an iron electrode was integrated to the electrochlorination system as a second anode, and 100% organic pollutant removal can be achieved. In the iron-modified electrochlorination (IMEC) process, Fe2+ from the iron anode could react with the electrogenerated HClO, inducing the steady generation of iron-oxo (FeIVO2+) by a radical scavenger, probe experiments, and DFT calculation analyses. In comparison to the·OH-dominated processes, the majority of intermediates was biodegradable and moderately toxic for different aquatic organisms in the IMEC process, as indicated by in silico prediction. Furthermore, the coagulation mechanism could contribute to 23.3% removal of the total organic carbon in the pH adjustment process to the circumneutral level, and the coagulant aids further enhanced the coagulation efficiency to 41.4%. Finally, the system was found to be excellent for antibiotics removal in mariculture wastewater and costed an order of magnitude less than the most reported ferrate-based processes. Overall, the research pioneers an electrochemical FeIVO2+-dominated technology for efficient purification of saline water, and the ecofriendly and cost-effective properties endow it with a huge application potential in the saline wastewater.