Photocatalytic Decolorization of Methyl Orange Solution with Phosphotungstic Acid

Photocatalytic decolorization of Methyl Orange (MO) solution has been studied using phosphotungstic acid (HPA) as photocatalyst. The decolorization reaction of MO solution is photocatalysis. The paper reveals that the optimal loading of photocatalyst for decolorization of MO solution (10 mg/L) is 0.6 g/L. The results show that the photocatalytic decolorization reaction of MO with HPA in a homogenous solution can be described by Langmuir-Hinshelwood equation; the results manifest that the reaction is first order with lower concentration, the limiting rate constant and the adsorption constant in this case are 0.3378 mg/(Lmin) and 0.5988 L/mg, respectively. The effect of pH value on the decolorization efficiency was also demonstrated, where special attention was paid on the nature of photocatalyst itself. Several observations indicate that only hydroxyl radicals participate the photocatalytic decolorization of MO with HPA under UV irradiation.