Development of a ZnO–Graphene Oxide Composite for Enhanced Photodegradation of Sandalfix Orange P3R and Sandalfix Turquoise Blue PG Dyes Under Sunlight Irradiation

Rapid industrial growth has led to a serious pollution problem, primarily due to the discharge of wastewater containing significant amounts of organic pollutants, such as dyes, oils, and solvents. Among these, water pollution caused by dye-contaminated wastewater is particularly concerning. Conventional treatment methods have proven inadequate for the effective removal of dyes from wastewater. Sunlight-assisted photocatalysis has emerged as a promising approach for eliminating toxic organic substances from aqueous media. In this study, we report the development of ZnO-decorated graphene oxide (ZnO-GO) as a photocatalyst for the degradation of Sandalfix Orange P3R and Sandalfix Turquoise Blue PG dyes under sunlight irradiation. Graphene oxide was synthesized using the Hammer and Offeman method, and ZnO-GO composites were prepared via chemical reduction in a 1:1 ratio. The synthesized ZnO-GO was characterized using XRD, TEM, DR-UV-Vis, FTIR, and surface area analysis. Its photocatalytic performance was evaluated for the degradation of the two dyes. More than 95% of 100 mg/L (50 mL) of each dye was successfully degraded within 120 minutes of reaction time. ZnO-GO exhibited 2.2- and 1.9-fold higher catalytic activity in degrading Sandalfix Orange P3R and Sandalfix Turquoise Blue PG dyes, respectively, compared to graphene oxide and ZnO alone. This enhanced activity is attributed to the efficient transfer of photo-induced electrons through the graphene sheets, which play a crucial role in preventing the recombination of positive holes and electrons, thereby significantly improving photocatalytic performance.