Visible light-driven ZnCr double layer oxide photocatalyst composites with fly ashes for the degradation of ciprofloxacin

Zn-Cr layered double oxide/fly ash (ZnCrLDO/FA) composites were synthesized using three different fly ashes (YEM, DAT, PAN) as photocatalysts for the degradation of ciprofloxacin through in situ coprecipitation followed by calcination. Ciprofloxacin (10 mg/L) was completely decomposed more than 98% within 120 min by ZnCrLDO/YEM composites in aqueous conditions, which indicates that the heterojunction between ZnCrLDO and YEM may help electrons move easily to enhance the separation of the electron-hole pairs. Based on the XPS results for the three fly ash samples, the largest Fe and Ti content was detected on the YEM, which suggests that TiO₂, Fe₂O₃ on the surface of fly ash are responsible for the heterojunction. Furthermore, the ERDT pattern of ZnCrLDO/YEM confirmed the formation of new electronic levels that may avoid the recombination of electron-hole pairs, which leads to the enhancement of photocatalytic performance. These results show that fly ash is essential as supporting material to avoid the agglomeration of ZnCrLDO particles and as an electron carrier for enhancing the mobility of photogenerated electrons in photocatalyst composites.