Photocatalytic degradation kinetics of Congo Red dye by sol-gel TiO2 film

In this paper photocatalytic degradation of Congo Red dye in water solution was studied using TiO2 as a photocatalyst in the form of a nano film irradiated with UV-A light (365 nm). The TiO2 nano film was deposited on the borosilicate glass substrate by sol-gel dip coating method. For the preparation of TiO2 sol, the following components were used: titanium (IV) isopropoxide as the titanium precursor, propanol as a solvent, nitric acid as a catalyst and acetylacetone for peptization. Crystal structure of TiO2 was identified by X-ray diffraction (XRD) method. The photocatalytic degradation process of Congo Red dye was monitored by means of UV-Vis spectrophotometry. Experiments were performed at 25°C. The experimental results indicated that degradation rate of Congo Red dye follows pseudo first-order kinetics according to the Langmuir-Hinshelwood (L-H) model.