Photochemical Treatment of Blue-Indigo using TiO₂-Sunligth System in Heterogeneous Conditions.^†

Abstract: Ecuador is one of the countries in the Latin American region with high textile production. However, chemical treatment strategies in the Ambato, Tungurahua and Quito areas are inefficient and not systematically applied, and the volumes of dyes and pigment-type contaminants generate serious environmental problems. The treatments of indigo textile wastewater and related indigo derivatives are very complex. Taking theses into consideration, was developed a simple photochemical protocol, in heterogeneous conditions, for degrading “blue-indigo” (Ambato textile group) in solution, using TiO₂ (Degussa P25, with purity of ≈ 99 % and BET surface area 50 ± 15 m²/g) and solar light at lab scale. The photocatalytic oxidation of organic dye“blue indigo” in aqueous solution was assessed by solar irradiation, in the presence of TiO₂ particles. The effect of indigo concentrations, pH and TiO₂ loading for maximum degree of degradation were evaluated. The mineralization of “blue indigo” was reported by measuring COD-i and COD-f of the solution that was irradiated with sun light (60-100 minutes) under optimized conditions. Taking into consideration the results was proposed a probable mechanism of degradation .The results allows to re-design, in eco-sustainable conditions, for Ecuador, the strategies for controlling contamination in textile wastewaters.