High visible-light catalytic activity of Bis-PDI-T@TiO2 for activating persulfate toward efficient degradation of carbamazepine

Due to the low concentrations of pharmaceuticals and personal care products (PPCPs), traditional water treatment processes are difficult to degrade them effectively. 2,5-bis (tributylstannyl) thiophene-perylene diimide-T@TiO2 (Bis-PDI-T@TiO2) composite photocatalyst is firstly prepared by the bisolvent phase transfer method and has a good ability to activate persulfate (PS) under visible light. 5 ppm Carbamazepine (CBZ) (a typical PPCPs) can be completely degraded by 1.0 g/L prepared photocatalyst and 1.0 mM PS within 30 min in the 0.1 wt% Bis-PDI-T@TiO2 (PT0.1) system under visible light. Four species of reactive oxidizing species were identified for CBZ degradation, including sulfate radical (SO4 center dot-), hydroxyl radical ((OH)-O-center dot), superoxide radical (O-2(center dot-)), and positive hole (h(+)), and all contributed to CBZ degradation. Furthermore, the PT0.1 photocatalyst exhibits the high stability and recyclability. This study also proposed the reaction mechanism of the Vis/PS/Bis-PDI-T@TiO2 system and constructed a route of carbamazepine degradation in the coupled system.