Background: Over the last decades, many efforts have been made to improve the wastewater purification by developing suitable treatment methods for various pollutants removal. Most studies in this field have focused on heterogeneous photocatalysis which use semiconductor oxides, such as titanium dioxide (TiO₂). This useful technique is based on the pollutant decomposition by means of a chemical reaction occurring on a photocatalytic surface activated by light with a specific wavelength. The efficiency for removing of persistent organic pollutants such as azo dyes, photostability and inertness to chemical environment has made TiO₂ an important photocatalytic material. In this study, the photodegradation of an industrial textile dye Acid blue 113 (AB113), using anatase TiO₂ nanoparticles and ultraviolet (UV-A) radiation, has been performed in an aqueous heterogeneous medium.

Methods: The photocatalytic process was monitored by the UV–visible spectrometry, and different dosages of catalyst (10.00-60.00 mg), pH conditions (3-8), contact time (2-30 min), at the dye concentration of 25 mg/L were used. In addition, response surface methodology based on a three-variable three-level Box-Behnken design was employed to study and optimize the photocatalytic process. The interactive effects of three operational parameters including irradiation time, pH, and the catalyst amount on the dye degradation were analyzed.

Results: The dye degradation efficiency was accurately modeled by a quadratic equation with an R² of 0.9649. The optimum conditions for the dye removal were found at 29.78 min, pH 6.56 and catalyst dose of 42 mg in 100 mL of the solution. At this condition, 95.3% of the dye was removed.

Conclusion: The results show that anatase TiO₂ nanoparticles present excellent photocatalytic activity on the degradation of AB113 under UV irradiation. Therefore, the photodegradation of dyes using anatase TiO₂ nanoparticlesas can be efficiently used under optimum conditions for treatment of dye-containing industrial effluents.