Preparation of photocatalyst CNAA-1 for treating organic fluorine pollution: Applications, mechanism and toxicity assessments

Abstract

In this research, we carried out an in situ covalent modification of g-C₃N₄ via a two-step Schiff base reaction and successfully synthesized five photocatalysts, CNAA-1~5, which demonstrate outstanding photocatalytic degradation activity under visible light. Among them, CNAA-1(modified by p-aminobenzaldehyde and acetaldehyde) possesses the advantages of a large specific surface area, a wide range of photon energy absorption, a low recombination rate of photogenerated charge carriers, and the best photocatalytic degradation activity. Theoretical calculations suggest that the conjugation of the NC double bond with the heptazine ring in the g-C₃N₄ molecule can modify its electron cloud state and enhance electron-hole separation. Radical quenching experiments revealed that CNAA-1 can generate active species such as h⁺, ·O₂⁻, ¹O₂, and ·OH free radicals to facilitate the degradation of ciprofloxacin and fluridone and diminish the herbicidal activity of fluridone against D. sanguinalis. Through the Toxicity Estimation Software Tool (T.E.S.T), it was disclosed that the photocatalytic degradation system of CNAA-1 is capable of reducing and attenuating the acute and developmental toxicity of ciprofloxacin and fluridone. This system holds the potential for addressing water pollution issues caused by ciprofloxacin and fluridone.