Chitosan modified zirconium/zinc oxide as a visible light driven photocatalyst for the efficient reduction of hexavalent chromium

Abstract

Metal-sensitized biopolymeric hybrid materials can be strategically utilized in photo catalysis due to the behavior of their absorption band lying in the solar radiation spectrum. Herein, chitosan supported zirconium(Zr)/zinc oxide (ZnO)) in the preparation of photo catalyst (Zr-ZnO@CS) for photocatalytic reduction of hexavalent chromium(Cr⁶⁺⁾. Moreover, photocatalytic testing factors like exposure time of light, pH, initial Cr⁶⁺ concentration, and influence of co-anions on the removal of Cr⁶⁺ by Zr-ZnO@CS were also examined. Langmuir-Hinshelwood kinetic model suggested the surface reaction was the rate-controlling step. The removal mechanism of Zr/ZnO@CS was because of enhanced properties like positive positioning of the band gap, boosted charge excitation, and higher dynamic sites. Field trial results showed that Zr-ZnO@CS hybrid photocatalyst demonstrates the potential application for the reduction of Cr⁶⁺ ions.

Keywords: Chitosan; Photodegradation; Zirconium; ZnO.