Constructing Tandem Fenton‐like Reaction Systems Based on Structure Adaption to Boost Water Contaminant Mineralization Efficiency

Mineralization of emerging contaminants by using advanced oxidation processes (AOPs) is a desirable option to ensure water safety, but still challenged by the excessive chemical and/or energy input. Here, we conceptually proposed the tandem reaction system (TRS) of different reactive oxygen species (ROS) based on structure adaption of target contaminants. To construct a model TRS, we first realized highly selective generation of three classical ROS (1O2, HO• and SO4•–) by peroxymonosulfate activation in an electrochemical Fenton‐like system, where three replaceable Fe‐centered cathodes were rationally designed as electronic mediator. The 1O2+SO4•–‐TRS exhibited nearly 100% mineralization of sulfamethoxazole (SMX), whereas only 34.2%, 56.2% and 60.8% for each of the single 1O2/HO•/SO4•–‐AOP systems. Mechanism exploration of SMX degradation in TRS evidenced that the initial reaction with 1O2 selectively destructed the sulfonamide bridge of SMX to form p‐aminobenzenesulfonic acid, which will be vulnerable to sequent SO4•– attack to facilitate mineralization. Successful extendibility of 1O2+SO4•–‐TRS to other sulfonamide antibiotics and 1O2+HO•‐TRS to phenolic and arylcarboxylic compounds, as well as the demonstration of 1O2+SO4•–‐TRS in treatment of three actual pharmaceutical wastewaters strongly support that TRS is a powerful and sustainable strategy to enhance the mineralization of emerging contaminants in water.