Abstract <p>This study aims to optimize the synthesis parameters of iron-exchanged bentonite catalysts prepared by solid phase and liquid phase ion exchange methods for photo-Fenton degradation of methylene blue. A central composite design was employed to investigate the effects of temperature, time, and iron-to-bentonite ratio on the photo-Fenton activity of the synthesized catalysts. The results showed that the optimized catalysts exhibited high decolorization efficiency, with removal percentages of up to 85% and 80% for solid phase and liquid phase ion exchange methods, respectively. The optimized conditions were found to be 175.68°C, 20.27% iron, and 84.73 s for solid phase ion exchange, and 150.67°C, 79.73% iron, and 48.24 min for liquid phase ion exchange. The response surface methodology and analysis of variance (ANOVA) revealed that the quadratic model was suitable for describing the relationships between the synthesis parameters and photo-Fenton activity. The study demonstrates the potential of iron-exchanged bentonite catalysts prepared by optimized solid phase and liquid phase ion exchange methods for efficient photo-Fenton degradation of methylene blue.</p>