Anionic polyelectrolyte modified perovskite composite activated hydrogen peroxide to treat high-salinity organic wastewater: Dual effects of electrostatic interaction

Due to the quenching of free radicals, high-salinity organic wastewater has become a pain point in the practical application of advanced oxidation processes (AOPs). In this work, a Poly (sodium 4-styrenesulfonate) (PSS) modified lanthanum ferrite and ceria composite (A-Ce/LaFe) was used to activate hydrogen peroxide (H2O2) for methylene blue (MB) degradation. The -SO3- in the PSS molecule brings about electrostatic interactions between the catalyst and environmental substances. The electrostatic repulsion forces anions (Cl-, HCO3–, etc.) to move away from the catalyst surface and prevent them from approaching and quenching free radicals. The electrostatic attraction causes a large number of cationic MB molecules to be adsorbed to the catalyst surface, thereby improving the local concentration and contact efficiency. In the typical high-salinity organic wastewaters (30000–70000 mg·L-1), A-Ce/LaFe achieves complete degradation of MB within 30 min, significantly superior to FeSO4 and ordinary perovskite. In addition to cationic pollutants, A-Ce/LaFe can effectively degrade electrically neutral pollutants in high-salinity organic wastewater. The synergistic effect of Fe2+/Fe3+ and Ce3+/Ce3+ electron transfer caused a large number of hydroxyl radicals generated by hydrogen peroxide decomposition became the dominant reactive oxygen species. This work has certain enlightening significance for high-salinity organic wastewater treatment by free radicals based AOPs.