Construction of magnetically separable dual Z-scheme g-C3N4/α-Fe2O3/Bi3TaO7 photocatalyst for effective degradation of ciprofloxacin under visible light

Insufficient photocatalytic activity and poor recyclability are considered as two main factors that limit the further application of photocatalysts in environmental remediation. Herein, a new magnetic g-C3N4/α-Fe2O3/Bi3TaO7 (CN/FO/BTO) heterojunction with dual Z-scheme system was first synthesized via an ultrasound-assisted calcination process. The results showed that the removal efficiency of ciprofloxacin (CIP) by optimized CN/FO/BTO heterojunction could reach 95.6% within 120 min illumination of visible light, which was 6.1, 15.9, 5.2, 3.7 and 2.3 times as much as that of single CN, FO, BTO, binary CN/FO and CN/BTO, respectively. Characterization analysis indicated that the improved photocatalytic activity derived from the synergistic effects of the three components, including the dispersion of FO and BTO by CN sheet, the enhanced light absorption of CN by addition of FO and BTO, and the reduced photogenerated charge recombination by their intimate contact. Further mechanism study revealed that the dual Z-scheme system of CN/FO/BTO leaded to efficient photoexcited carrier separation and strong redox capacity, in which •O2– and •OH were main radicals during photocatalytic process. Meanwhile, CN/FO/BTO possessed supreme adaptability to pH as well as co-existing matters, favorable magnetic separation property and excellent stability, making it a potential candidate for environmental remediation applications.