Heterogeneous photocatalysis coupled with Fenton-Like reaction for fluoroquinolone antibiotics degradation by poly (Triazine Imide): From mechanism to application in a continuous flow catalytic system

The coupling of photocatalysis and heterogeneous Fenton-like reactions gains much interest as the possibility of synergy or enhanced effect between them, nevertheless, the development of catalysts and reaction systems are the main research focus for implementing the coupled technique for practical utilization. In this work, poly (triazine imide) (PTI), an ordered polymeric carbon nitride analogous to of g-C3N4, was firstly reported to be effective for activating peroxymonosulfate (PMS) to degrade micropollutants in a continuous flow catalytic system under visible light. Photogenerated charge separation and transfer occurred on {0001} facets of hexagonal PTI nanoplates, where binding of PMS molecules shortened the O-O bonds and elongated the O-H bonds of PMS, resulting in singlet oxygen (1O2) for the complete removal of antibiotics within 30 min. Besides, the immobilized PTI can maintain high degradation and mineralization rates of 96.8 % and 60.4 % respectively, after 8 h operation in a continuous flow reactor of laboratory scale size, and achieve a stable catalytic efficiency of 84.6 % for 1.7 L of wastewater in 48 h. This study provided an in-depth mechanistic understanding on coupling of photocatalysis and PMS activation, well addressed the problems of catalyst recycling, and validated the great potential of applying this coupled technique for environmental remediation.