In-situ preparation of highly dispersed Fe doping C3N5 induced by inorganic iron salts with effective activation of PMS for photocatalytic degradation of chlortetracycline

A highly dispersed Fe in situ doped C₃N₅ (Fe-C₃N₅) photocatalyst utilizing inorganic iron salt was successfully prepared, which was applied in photocatalytic synergistic advanced oxidative degradation of chlortetracycline (CTC) under the activation with persulfate. BET measurements revealed that uniform Fe doping increases the specific surface area, thus enhancing the reactive active sites. Photoelectric tests indicate that Fe doping optimizes the energy band structure of C₃N₅, thereby enhancing electron transfer, and the photogenerated electrons facilitate the Fe²⁺/Fe³⁺ redox cycle, which is beneficial for the sustained and efficient activation of persulfates. The Fe-C₃N₅(50 %)/PMS/Vis system achieved over 95 % degradation of CTC within 2 h, after four cycles, the Fe-C₃N₅(50 %) still exhibits good reusability and stability. Free radical quenching experiments coupled with EPR spectroscopy identified ¹O₂, h⁺, and ·O₂^- as the dominant reactive species driving the degradation of CTC, elucidating the potential degradation mechanisms. Based on LC-MS measurements and utilizing the TEST toxicity assessment software, it has been determined that CTC ultimately decomposes into non-toxic small molecules, such as CO₂ and H₂O. Furthermore, a hydroponic germination experiment using mung beans was conducted to demonstrate that Fe-C₃N₅(50 %) does not exhibit toxic effects on plant growth. Importantly, this study offers novel insights into the green synthesis of highly dispersed Fe doping C₃N₅ photocatalytic for the efficient degradation of CTC.