Dependence of kinetics and pathway of acetaminophen photocatalytic degradation on irradiation photon energy and TiO2 crystalline

Abstract Degradation kinetics and pathway of acetaminophen (APAP) on anatase TiO 2 , rutile TiO 2 and anatase–rutile mixed TiO 2 were investigated at UVC 254 nm and UVA 366 nm in a wide photon flux region in the present work. Hydroxyl radicals ( OH) induced hydroxylation is the predominant pathway for the degradation of APAP on anatase or anatase containing TiO 2 particularly under UVC irradiation, which accounted for more than 50% of total degradation. Valance band hole ( h VB ) induced one electron oxidation contributed approximately 70% of the degradation of APAP on rutile TiO 2 under UVA 366 nm irradiation, while direct photolysis contributed more than rutile TiO 2 photocatalysis under UVC 254 nm irradiation because of competition for irradiation photon between APAP and rutile TiO 2 . These results showed that contribution of OH and h VB on anatase TiO 2 is independent of irradiation photon energy, while irradiation photon energy significantly influences the contribution of OH, h VB and direct photolysis to the degradation of APAP on rutile or rutile containing TiO 2 . Therefore, degradation patterns of APAP and maybe other phenols in TiO 2 photocatalysis process could be controlled through changing irradiation photon energy and TiO 2 crystalline, which will make TiO 2 photocatalysis a selective oxidation system.