This study aims to compare the anionic dye degradation (Titan yellow dye: DY9) in synthetic solution using three advanced oxidation processes, namely, Fenton process (FP) (H 2 O 2 /Fe 2+ ), photo-Fenton process (PhFP) (UV/H 2 O 2 / Fe 2+ ), and photocatalytic process (PhCP) (TiO 2 /UV). To perform this study, design of experiments methodology was applied. A full factorial design was