Photocatalytic degradation of yellow 2G dye using titanium dioxide/ultraviolet A light through a Box–Behnken experimental design: Optimization and kinetic study

Yellow 2G (Y2G), a type of anionic, synthetic monoazo dye that is widely used in household applications, textiles, and food industries, has been found to have cardiovascular and neurological effects on all living beings. In the present study, heterogeneous photocatalytic degradation of commercial Y2G was conducted using pure titanium dioxide (TiO₂) in a batch reactor system under ultraviolet A (UVA) light for 180 min. TiO₂ dosage, pH, and initial Y2G concentration were the three experimental parameters selected and studied to obtain preliminary information about the photocatalytic activities within a specified range. The Box–Behnken design method (BBD) was used to determine optimal values of the results using the above parameters of Y2G photocatalysis under response surface methodology (RSM). The optimum conditions were 0.914 g L⁻¹ TiO_2, pH 3.45, and an initial Y2G concentration of 20 mg L⁻¹. The Y2G degradation efficiency was 96.19% using a second-order polynomial equation with R² ≈ 0.999. The experimental results also showed that the photocatalytic process could be successfully explained using the modified Langmuir–Hinshelwood model, where k_c and K_LH were 0.787 mg L⁻¹ min and 0.010 L mg⁻¹, respectively.