Tailoring photocatalytic performance through Fe-doped TiO2/ZnO for effective remediation of organic contaminants

Abstract

The development of highly efficient photocatalysts holds significant promise for addressing contemporary environmental challenges. This study focuses on the synthesis and characterization of a novel photocatalyst, iron-doped TiO₂/ZnO particles, created through the sol-gel technique. The incorporation of iron ions into the crystalline structure of TiO₂/ZnO aims to enhance the photocatalytic efficiency of TiO₂. The findings revealed that Fe–ZnO/TiO₂ exhibits a more thermally stable lattice compared to TiO₂/ZnO, thereby retarding the phase transformation from anatase to rutile under higher calcination temperature. The photocatalytic performance of the synthesized photocatalyst was evaluated through the degradation of methyl orange under visible light irradiation. A statistical response surface methodology based on a central composite design was employed to develop a predictive model for color removal (as the dependent variable) considering variations in irradiation intensity, initial color concentration, catalyst concentration, reaction time, and pH (as independent variables). The analysis of variance identified the initial color concentration as the most influential factor, negatively affecting the predicted response. The experimental values of color removal exhibited good agreement with the predicted values from the regression model with a coefficient of determination of 0.949, indicating the accuracy of this model in predicting the mentioned outcomes. The presented model indicated that, for a sample of methyl orange with an initial concentration of 21.97 ppm, a reaction time of 117.69 min under direct irradiation of 21.63 W, a catalyst concentration of 0.61 g/L, and a pH of 4.74, the optimal color removal efficiency of 78.99 % was achieved.