Hydrothermal fabrication of ZnS/chitosan composite for effective photocatalytic degradation of Eosin blue and inactivation of bacterial pathogens

Abstract

In this study, a ZnS/chitosan composite was synthesized through hydrothermal and evaluated for its photocatalytic performance in degrading Eosin blue (EB) dye under visible light. Analytical instruments were employed in this study to examine the optical, electronic, structural, thermal, chemical properties of prepared bare ZnS and ZnS/chitosan composite. The bandgap energies of hydrothermally prepared ZnS and ZnS/chitosan composite were 3.02 eV and 2.71 eV, respectively, with crystalline size found to be 29.1 nm for composite which is slightly larger than bare ZnS with 26.8 nm due to addition of biopolymer to metal sulfide. Further, the photocatalytic performance of prepared samples was executed over the degradation of EB dye under visible light illumination. Optimized conditions are pH 9, 0.1 g catalyst loading amount, 10 mg/L EB dye initial concentration and 90 min. A possible degradation mechanism was proposed based on the generation of reactive oxygen species under light irradiation. Reusability tests demonstrated consistent degradation performance, with a decrease from 100% in the first run to 71.6% in the seventh cycle. The proposed photocatalyst was the most effective for the inactivation of S.aureus with 22 mm and it is suitable for wastewater treatment effectively.