Constructing Tandem Fenton-like Reaction Systems Based on Structure Adaption to Boost Water Contaminant...

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.