Influence of TiO2 Phases and Operational Parameters on Photocatalytic Degradation of Methyl Orange

In the textile industry, the wastewater produced consists of large amount of dyes. These dyes possess harm to environmental and public health. TiO2 is one of the most common photocatalysts, however studies about degradation efficiency of dye using different phases of TiO2 is scared. Employing photocatalysis, the novelty of this study is to compare methyl orange (MO) degradation efficiency of pure phases of photocatalysts TiO2 (anatase, rutile and brookite) in terms of their photochemical properties and underlying photocatalytic mechanism. Characterisation evaluations including scanning electron microscopy (SEM), fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and electrochemical impedance spectroscopy (EIS) were carried out to assess morphology, chemical structure, crystal structure and electron transfer resistance of the photocatalysts. MO adsorption-photocatalysis removal percentage by pure phase TiO2, which are anatase, brookite and rutile were attained at 57%, 48% and 19%, respectively. The main reason that contributes to high degradation rate of MO by TiO2-anatase could be due to the good dye-photocatalyst affinity and the least electron transfer resistance. Besides, other affecting parameters such as initial concentration of photocatalyst, initial concentration of dye and pH of the dye solution were evaluated. It was found that photocatalytic efficiency was enhanced with increasing initial concentration of photocatalyst from 0.25 mg/mL to 1 mg/mL (degradation improved from 50% to 80%), with decreasing initial dye concentration and under acidic condition.