Photocatalytic degradation of glyphosate using TiO₂/Al₂O₃ using Box-Behnken Design

¹ Faculty of Earth Science, Universiti Malaysia Kelantan, Jeli Campus, 17600 Jeli, Kelantan, Malaysia
² Faculty of Bioengineering and Technology, Universiti Malaysia Kelantan, Jeli Campus, 17600 Jeli, Kelantan, Malaysia

^* Corresponding author: nraihan@umk.edu,my

Abstract

The TiO2/Al2O3 photocatalyst was produced through a hydrothermal process. The experiment was based on Box-Behnken design (BBD) considering three factors with three levels. A total of 17 experiments were designed and conducted to study the effect of variables such as TiO2/Al2O3 photocatalyst ratio (50:50 - 90:10), TiO2/Al2O3 photocatalyst amount (1.0 g – 40.0 g), and initial concentration of glyphosate (5.0 - 10.0 mg/L) on the percentage of degradation. Glyphosate degradation was conducted under UV light for three hours and monitored using a UV-Vis spectrophotometer (DR6000 HACH). Regression analysis was used to model the experimental results, and a quadratic model was established to study the effect of selected variables on the percentage of degradation. The optimal degradation percentage of 99.87% at the ratio of 50:50 TiO2 to Al2O3, the amount of 40.0 g photocatalyst TiO2/Al2O3 used, and the initial concentration of glyphosate 7.5 mg/L was obtained from the developed RSM model, and the optimized conditions were verified with experimental results. The degradation percentage was predicted using a second-order polynomial model, and the coefficient of determination (R²) were determined as 0.9133. Process variables optimized for percentage degradation were a good match for the BBD method. Finally, the prepared TiO2/Al2O3 photocatalyst was beneficial in degrading herbicides.