Solar, visible and UV light photocatalytic activity of CoWO₄ for the decolourization of methyl orange

Abstract

The photocatalyst CoWO₄ was synthesized by co-precipitation method with slight modification and well characterized by FT-IR, UV–vis diffuse reflectance spectra, X-ray diffraction, AFM and field emission scanning electron microscope techniques. The elemental composition present in the photocatalyst was confirmed by recording EDX spectrum. The photocatalytic activity of CoWO₄ for the decolourization of methyl orange (MO) was investigated under solar, visible and Ultra-Violet (UV) light irradiation. The remarkable photocatalytic decolourization of MO was achieved under solar and visible light irradiation than that of TiO₂. The high surface area of 55.0527 m²/g enhances the adsorption of anionic dye MO on the surface of the positively charged catalyst at pH 3 thus increases the photocatalytic activity. Under UV light irradiation, photocatalytic activity increases which may be due to high energy of photons. The essential parameters such as amount of catalyst, dye concentration and initial pH influence the photocatalytic efficiency of CoWO₄. The first order rate constant for the decolourization reaction was derived using Langmuir–Hinshelwood kinetic model.

Keywords:

• Photocatalysis
• Methyl orange (MO)
• UV-light
• Solar light
• Visible light
• CoWO₄
• Decolourization

Acknowledgement

The authors thank to DST-SERC for financial support, sanction no. SR\FT\CS-042\2008 and Anna University, BIT Campus, (erstwhile Anna University of Technology Tiruchirappalli) Tiruchirappalli, for supporting to carry out this work.