Ferrocene-based resin as heterogeneous fenton-like catalyst for efficient treatment of high salinity wastewater at acidic, neutral, and basic pH

As a classical advanced oxidation technology, the Fenton reaction is often criticized for having a narrow pH window, difficult recovery of catalysts, and generating iron-containing sludge. Furthermore, traditional Fenton reaction was also limited in treating high salinity wastewater. In this work, a ferrocene-containing resin is prepared and used as the heterogeneous catalyst for a Fenton-like reaction to treat different organic pollutants wastewaters in high salinity conditions under a wide pH range. Using ascorbic acid as a reducing agent, the Fenton-like reaction can degrade different organic pollutants such as methylene blue, bisphenol A, bisphenol S, tetracyclines, and 4-nitrophenol within 10 min in high salinity conditions (500 mmol/L) at a wide range of pH values from acidic to basic. In mechanism investigation, singlet oxygen and superoxide radicals were identified as the primary reactive oxygen species. It was straightforward to recover the resin from water, and the degradation ratio exceeded 99% in five consecutive experiments. Such a Fenton-like reaction could also efficiently regenerate the resins to restore their adsorption capacity without using acid, base, or organic solvents.