Kinetics and thermodynamics study for photodegradation of Brown HT dye by MnO and NiO as catalysis

Abstract

The photo-catalyzed oxidation process of Brown HT dye was studied in the aqueous solution of the dye, using an irradiation source (ultraviolet rays UV) with the use of manganese oxide (MnO) and nickel oxide (NiO) catalysts, where the effect of increasing the weight of the catalyst in the range of 0.05–0.8 g was studied using a fixed concentration of dye 20 ppm, The best weight gave the highest dissociation rate of the dye 0.1 g from MnO and 0.075 g from NiO, and at the best weight the effect of many factors on it was studied, including pH, change of initial dye concentration, and temperature. The effect of changing the pH in the range (2–10) was studied, and the best pH gave the highest rate of dissociation of the dye at pH = 2 in the presence of MnO and pH = 4 in the presence NiO when using UV as an irradiation source. The effect of changing the initial concentration of the dye in the range of 10–50 ppm was studied, as the higher the concentration, the lower the dissociation rate. Accordingly, there is an inverse relationship between the initial concentration and the dissociation rate. The effect of changing the temperature in the range (298–323) K was studied. It was found that the higher the temperature, the greater the dissociation rate. Accordingly, the relationship is direct between temperature and reaction speed, and the activation energy for each reaction was calculated using the Arrhenius equation.