Magnetically separable CuFe2O4/ZnIn2S4 heterojunction photocatalyst for simultaneous removal of Cr(VI) and CIP

Although photocatalytic has been widely applied for wastewater treatment, there is still a need to develop highly efficient materials capable of simultaneous removal of pollutants and heavy metal ions. This study used a combination of electrospinning and solvothermal methods to prepare CuFe2O4/ZnIn2S4 (CFO/ZIS) heterojunction photocatalysts, and studied their photocatalytic performance in a Cr(VI)-Ciprofloxacin (CIP) coexisting pollutant system. Under simulated sunlight irradiation, the optimal ratio of CFO/ZIS composites (CFO/ZIS-2) achieved a reduction rate of about 99% for Cr(VI) within 20 min, and a degradation rate of about 73% for CIP within 60 min. In addition, even under real sunlight or lake water conditions, CFO/ZIS-2 has the ability to simultaneously remove Cr(VI) and CIP. Most importantly, after the completion of the photoreaction, the magnetism of CFO/ZIS-2 itself can be easily separated with a magnet, indicating that CFO/ZIS-2 has certain practical application capabilities. In addition, cyclic experiments have shown that CFO/ZIS-2 has a certain degree of repeatability and demonstrated that the formation of heterojunctions inhibits photo-corrosion of the catalyst. The formation of heterojunctions in CFO/ZIS-2 was demonstrated through free radical capture experiments and molecular probe experiments, which reduced the recombination of photo-generated electron-holes and enhanced light absorption. This work will provide a new avenue for designing novel magnetic separation and photo-corrosion-resistant photocatalysts to cope with complex wastewater environments.