Z-scheme heterojunction composed of Fe-doped g-C3N4 and Bi2MoO6 for photo-fenton degradation of antibiotics over a wide pH range: Activity and toxicity assessment

Abstract

In photo-Fenton technology, the narrower pH range limits its practical application for antibiotic wastewater remediation. Therefore, in this study, a Z-scheme heterojunction photo-Fenton catalyst was constructed by Fe-doped graphite-phase carbon nitride in combination with bismuth molybdate for the degradation of typical antibiotics. Fe doping can shorten the band gap and increase visible-light absorption. Simultaneously, the constructed Z-scheme heterojunction provides a better charge transfer pathway for the photo-Fenton reaction. Within 30 min, Fe₃CN/BMO-3 removed 95.54% of tetracycline hydrochloride (TC), and its remarkable performance was the higher Fe³⁺/Fe²⁺ conversion efficiency through the decomposition of H₂O₂. The Fe₃CN/BMO-3 catalyst showed remarkable photo-Fenton degradation performance in a wide pH range (3.0-11.0), and it also had good stability in the treatment of TC wastewater. Furthermore, the order of action of the active species was h⁺ > ·O₂^- > ¹O₂ > ·OH, and the toxicity assessment suggested that Fe₃CN/BMO-3 was effective in reducing the biotoxicity of TC. The catalyst proved to be an economically feasible and applicable material for antibiotic photo-Fenton degradation, and this study provides another perspective on the application of elemental doping and constructed heterojunction photo-Fenton technology for antibiotic water environmental remediation.

Keywords: Tetracycline; Toxicity assessment; Z-scheme heterojunction; photo-Fenton.