Photo-Fenton-like degradation of azo dye methyl orange using synthetic ammonium and hydronium jarosite

► Hydronium and ammonium jarosite could catalyze the oxidation of methyl orange in photo-Fenton-like process. ► The oxidation process is essentially heterogeneous, not homogeneous. ► Hydronium jarosite has stronger reactivity than ammonium jarosite.