Application of photocatalysis for the decontamination of water contaminated with the Acid Orange 10 dye in the presence of TiO2 under irradiation.

The photocatalytic degradation of the Acid Orange 10 was carried out in a static reactor used for direct photolysis under polychromatic external lighting. Acid Orange 10 (Orange G: OG), is used in silk, wool products and dyeing. It is a recalcitrant dye, which resist to oxidation and thermal degradation, and persists in the aquatic environment. The photodegradation is one of the most studied processes over the last two decades and its large-scale application has grown steadily. As we will see below, the entity that absorbs light is a semiconductor characterized by a narrow forbidden band. The photodegradation of OG onto TiO₂ material has been investigated at batch conditions. The effects of contact time (0–60 min), initial pH (3–11), adsorbent dose (0.1–1 g/L), and OG concentration (10–40 mg/L) on the OG oxidation by TiO₂ have been studied. High light intensity increases the degradation efficiency. The experimental results have shown that the photocatalytic efficiency is proportional to the dose of catalyst, which above a threshold value becomes almost constant and depends on the pH. The adsorption is an important step controlling the apparent kinetic constant of the photocatalysis. The photodegradation rate was favored for high OG concentrations in agreement with the Langmuir–Hinshelwood model with constants Kr and K_ad are respectively 0.4780 L mg/min and 0.7823 L/g. The degradation rates are pH and temperature dependent with a high degradation at high temperatures. TiO₂ has a better activity for the OG degradation, compared to many catalysts available in the literature. [ABSTRACT FROM AUTHOR]