Removal of indigo dye by photocatalysis process using Taguchi experimental design

The major concern of the present research is degradation of hazardous and stable Indigo dye used in industrial denim dying process. For this purpose, a heterogeneous photocatalysis process was carried out to treat aqueous solution of Indigo dye using pure titanium dioxide ($TiO_2$) in a batch reactor system under ultraviolet A (UVA) light for 210 min. In the study, individual and synergistic effects of factors such as $TiO_2$ dosage, pH, and initial dye concentration were scrutinized. Moreover, Taguchi statistical method was performed to optimize influential parameters. The results obtained from the study that $TiO_2$ concentration had the most effective factor on the Indigo dye degradation. The optimal conditions for dye removal were A (pH) at level 2 (4), B (initial dye concentration) at level 1 (10 mg $L^{-1}$) and C ($TiO_2$ concentration) at level 4 (1.5 g $L^{-1}$). The results presented that the theoretically predicted value for degradation efficiency (100%) was confirmed by the experimental value (100%).