The photocatalytic mineralization of Remazol Black B (RBB) in aqueous solution was studied under solar light in the presence of zinc oxide photocatalyst. Photocatalytic efficiencies were examined under various operating parameters such as initial dye concentration, addition of inorganic anions (NO₃^-, SO₄^2-, CO₃^2-, Cl^-) and oxidizing agent ([Fe(C₂O₄)₃]^3-). The optimum conditions for the degradation of RBB was found at dye concentration of 7×10^-5 mol/L and 1.20 g/100 mL of catalyst doses at pH 5.83. The addition of inorganic anions in aqueous medium hinders photodegradation efficiency by blocking the active sites. On the other hand, by the presence of ferrioxalate ion, the photocatalytic activity was inflated by 6% due to halting the recombination of e--h+ pairs by accepting photogenerated electrons. Kinetic study reveals that the whole photodegradation process was followed by pseudo-first order kinetic model.

Keywords: Photodegradation; Inorganic Anions; Semiconductor; Solar Light;