Photocatalytic removal of persistent pollutants using eco-friendly ZnO

The heterogeneous photocatalysis process using ZnO has played an important role in the elimination of emerging contaminants in aqueous media. In this context, this work aimed to synthesize a ZnO-based photocatalyst obtained through an alternative sol-gel route using cassava starch as a polymerizing agent and apply it in a photocatalytic system to remove persistent pollutants in an aqueous medium. The material obtained was characterized by different techniques. XRD results show that it is a high crystalline catalyst with peaks characteristic of ZnO, while FTIR proves that cassava starch was a crucial chelating agent in the synthesis. The band gap value of the catalyst was 3.06 eV, which comprises the visible light spectrum, resulting in an optical improvement of the photocatalyst. The material was used in a tartrazine yellow dye removal system, and the influence of process parameters was investigated. Through kinetics, the optimal removal point was determined at [Cat](0) = 0.5 g L-1, [TY](0) = 10 mg L-1, pH=12 and oxygenation, which reached 94% removal efficiency of the dye in 180 min of reaction. The chemical parameters COD and TOC confirmed the mineralization of the TY dye, resulting in 89% and 80% reduction, respectively. Thus, the results of this study demonstrate that the synthesis method shows the potential of this material as a sustainable and low-cost photocatalyst.