Fe-ZIF-8@AgCl Z-scheme photocatalyst for ciprofloxacin: Enhanced removal, degradation mechanism and pathway

Ciprofloxacin accumulates in aqueous environment due to its non-degradability. Photocatalysis, as an economical and efficient treatment technology for organic matter, is mostly used to remove antibiotics from water environment. However, the photocatalytic performance is limited by photocatalysts, which suffer from wide band gap and severe recombination of photogenerated electrons and holes. Therefore, we developed a Z-scheme heterojunction photocatalyst Fe-ZIF-8@AgCl, which was synthesized by combining pre-prepared Fe-ZIF-8 with AgCl. Meanwhile, the X-ray diffractometer, scanning electron microscopy, transmission electron microscopy, Brunauer-Emmett-Teller analysis and X-ray photoelectron spectroscopy were employed to characterize the structure of Fe-ZIF-8@AgCl, and a series of photoelectric tests were conducted to demonstrate the photocatalytic properties of Fe-ZIF-8@AgCl. The results revealed that Fe-ZIF-8@AgCl had a remarkable 71.9 % removal efficiency of ciprofloxacin by photodegradation in 120 min. Fe-ZIF-8@AgCl could help reduce band gap energy, inhibit the recombination of photoelectrons and holes, lower the charge transfer resistance, and enhance the photocurrent response. Furthermore, Fe-ZIF-8@AgCl still maintained a high photocatalytic performance after 4 cycles, and ·O 2 - was detected and identified as the main photocatalytic active factor. Subsequently, the charge transfer mechanism of direct Z-scheme heterojunction was proposed, and the photocatalytic degradation pathways of ciprofloxacin were analyzed. In this study, Z-scheme heterojunction photocatalyst was prepared and showed great potential for efficient photodegradation of ciprofloxacin.