Photocatalytic removal of antibiotics from natural water matrices and swine wastewater via Cu(I) coordinately polymeric carbon nitride framework

Abstract

In this study, an efficient metal to ligand charge transfer (MLCT) was successfully implanted into the Cu-CNF via the bonds of coordinated Cu(I) with organic N and few inorganic O atoms, avoiding the long-distance charge transport via HOMO to LUMO transition and accelerating the visible light absorption and exciton dissociation. • Cu-CNF with the efficient MLCTs exhibits enhanced photocatalytic efficiency. • Visible light absorption and exciton dissociation are intensified in Cu-CNF. • The C-Cl and C-N-C moiety of CTC-HCl are initially attacked in degradation process. • NO 2 -N and NH 3 -N restrain the removal efficiency of CTC-HCl in the swine wastewater. • Organic matter in natural water leads to the decreased CTC-HCl removal efficiency. The overuse of refractory antibiotics in animal husbandry has caused serious aqueous environment pollution. Polymeric carbon nitride (CN) based photocatalysis, a promising method to address antibiotic pollution issues, has encountered with restricted efficiency because of the sluggish charge transfer and unexploited water matrices influence. In this study, an efficient metal to ligand charge transfer (MLCT) was successfully implanted into the Cu(I) coordinately polymeric carbon nitride framework (Cu-CNF) via the bonds of coordinated Cu(I) with organic N and few inorganic O atoms. The Cu-CNF photocatalysts were endowed with high-efficient chlortetracycline hydrochloride (CTC-HCl) removal in deionized water. To insure the feasibility of the Cu-CNF in antibiotics removal from different water matrices, a systematical exploration covering the reaction kinetics, the physicochemical stability, and the influence of specific water matrices on CTC-HCl removal was carried out by various ways. Results showed that the photo-induced MLCT route with shorter transfer distance was able to broaden light absorption of CN in the whole visible region, contributing to more available excitons and accelerating separation of the photoexcited electron-hole pairs. The boosted active oxidative species (h + , O 2 − and ∙OH) in porous Cu-CNF were found to promote the dechlorination and benzene ring cleavage process to favor the final mineralization of CTC-HCl molecules. Under the synergistic influence of water constituents, the removal efficiency of CTC-HCl was highest in river water (68.2%), followed by tap water (45.7%), and swine wastewater (33.1%). It was found that the existence of the high concentration NO x -N and NH 3 -N in the swine wastewater were responsible for the collapsed removal efficiency of CTC-HCl. Natural organic matter in river water and tap water was the main factor for the decreased CTC-HCl removal efficiency.