Visible light assisted photocatalytic degradation of diclofenac using TiO2-WO3 mixed oxide catalysts

Abstract

The TiO2-WO3 catalysts were synthesized using hydrothermal method with different molar ratios of tungsten (W) precursor. The prepared catalysts were characterized using different techniques and assessed for its photocatalytic efficiency in the degradation of diclofenac under visible light irradiation. It was found that all the prepared catalysts produced better performance than the pure TiO2 under the visible light irradiation. It was observed that the mineralization of diclofenac reached up to 91% within 4 h of treatment. The effect of the initial diclofenac concentration, pH and catalyst loading were also investigated. The improved photocatalytic activity of the TiO2-WO3 mixed oxide catalysts could be attributed to the enhanced electron-hole separation under visible light. The TiO2-WO3 mixed oxide catalysts were further analysed for its stability in aqueous environments and the results revealed that the as-prepared photocatalyst remains highly active and the efficiency was retained up to 80% over the repeated reaction cycles. LC–MS analysis revealed that several degradation products were formed during the course of irradiation and their degradation pathway primarily follows hydroxylation, dechlorination and decarboxylation reactions.