Synergistic mechanisms of novel Z-Scheme N,S co-doped biochar-based Ag3PO4 composites for efficient removal of norfloxacin

In this study, a novel N, S-co-doped carbon-based Ag3PO4 composite photocatalyst (N,S-Ag3PO4@ACB) was synthesized using activated biochar (ACB) as a carrier and used for the efficient removal of norfloxacin (NOR), a typical bio-refractory antibiotic. We systematically investigated the degradation effects, actual wastewater treatment, the impacts of environmental factors, and the degradation pathways. The results show that N,S-Ag3PO4@ACB is essentially a p-n heterojunction with Z-scheme of Ag2S/Ag3PO4/ACB composite containing Ag nanoparticles. After 120 min of irradiation, N,S-Ag3PO4@ACB removed 90.42% of an initial NOR concentration of 50 mg L–1. The activation of graphitic N and the lone electron pairs of N and S, promoted rapid photogenerated charge transfer. Furthermore, the surface properties of ACB promoted free radicals generation, and the surface plasmon resonance effect of the Ag nanoparticles synergistically enhanced the photocatalytic activity. A new degradation intermediate of NOR was identified, and the degradation dynamics were elucidated with three main pathways.