In-situ production and activation of H2O2 over hydroxyapatite modified CuFeO2 for self-sufficient heterogeneous photo-Fenton degradation of doxycycline hydrochloride

The self-sufficient heterogeneous photo-Fenton (SH-PF) system was constructed for doxycycline hydrochloride (DOH) degradation with hydroxyapatite (Hap) modified CuFeO 2 (Hap/CuFeO 2 ) composites through H 2 O 2 in-situ production. The modification of Hap could improve the specific surface area, visible-light response, light conversion efficiency, photoelectron lifetime and oxygen vacancies (OVs) of CuFeO 2 , which was conducive to H 2 O 2 production and DOH degradation in SH-PF system. Notably, Hap/CuFeO 2 fabricated with 0.5 g Hap (Hap/CuFeO 2 -0.5) displayed more superior performance for DOH degradation compared to other synthesized catalysts. The Hap/CuFeO 2 -0.5 load and initial solution pH for DOH degradation in SH-PF system were optimized, and the Hap/CuFeO 2 -0.5 had good reusability and stability. The • OH was the main active species for DOH degradation, and the facilitation effect of • O 2 – and photoelectrons on DOH degradation was associated with the H 2 O 2 production in the present work. In addition, the capture of photogenerated holes suppressed the recombination of photogenerated carriers, elevating the production of photoelectrons and thereby enhancing H 2 O 2 production and DOH degradation. The degradation pathways for DOH were proposed and the comprehensive toxicities of DOH were relieved after degradation in SH-PF system.