ZnO assisted photocatalytic degradation of acridine orange in aqueous solution using visible irradiation

A detailed investigation of photocatalytic degradation of the dye, acridine orange, has been carried out in aqueous heterogeneous medium containing ZnO as photocatalyst in a batch reactor. Visible light in the absence of ZnO has negligible effect on degradation. The disappearance of the dye, monitored spectrophotometrically, follows approximately pseudo-first order kinetics according to the Langmuir–Hinshelwood model. The total degradation of dye was tested using the chemical oxygen demand (COD) method. The addition of an optimal amount of hydrogen peroxide and potassium persulphate increases the degradation rate while NaCl and Na₂CO₃ decreases. The effect of addition of cationic and anionic surfactants has also been investigated. Bubbling of nitrogen in the reaction solution decreases the reaction rate. ZnO has been found experimentally to be a highly efficient photocatalyst for the degradation of acridine orange dye and hence there is a great potential in the treatment of organic pollutants such as dyes.