Enhanced photocatalytic activity of Fe2O3@ZnO decorated CQD for inactivation of Escherichia coli under visible light irradiation

The present study, magnetically separable Fe2O3@ZnO/CQD nanocomposite was successfully prepared via hydrothermal process and characterized with SEM-EDX, XRD, FTIR, VSM and DRS analysis. The effect of operational parameters includes photocatalyst dosage, photocatalyst type, CQD content and Escherichia coli (E. coli) concentration were evaluated on the E. coli inactivation. The disinfecting ability of nanocomposite components was obtained as Fe2O3@ZnO/CQD> Fe2O3@ZnO> ZnO> Fe2O3> CQD which shows a synergetic effect among different components. The highest E. coli inactivation rate (Kmax=0.7606 min-1) was obtained at photocatalyst dosage of 0.2 g/L and 15% CQD content. The MIC and MBC values value for E. coli were determined 0.1172 mg/mL and 0.4948 respectively that the results tests proved the antibacterial functions of the Fe2O3@ZnO/CQD. Nanocomposite showed the high reusability after 4 consecutive cycles, Kmax decreased from 0.7606 min-1 to 0.6181 min-1. Quenching experiments showed •OH and h+ are the main reactive oxygen species involved in the E. coli inactivation.