Decolourization of Methylene Blue in Aqueous Solution by Photocatalytic Oxidation, Fenton Oxidation and Biosorption

Abstract

The aim of the study was to investigate decolourization of Methylene Blue (MB) in aqueous solution using advanced oxidation processes (AOPs) and biosorption comparatively. Photocatalytic decolourization of MB was studied using TiO2 as catalyst. The photocatalytic decolourization of MB by direct UV irradiation alone, only TiO2 and TiO2/UV processes was investigated. It was found that decolourization by photocatalytic process of MB increased with decreasing pH, and decolourization rate also increased in the presence of TiO2/UV when compared to UV irradiation alone. Decolourization of MB was also studied with using the Fenton process (Fe(II)/H2O2). Concentrations of Fe(II) and H2O2 on decolourization ratio were investigated. The optimum catalyst to H2O2 ratio was found 1:3 at pH 4.0. In the second part of the study, the biosorption process was conducted with using plant gall immobilised alumina. The removal percentages were calculated with both plant gall immobilised alumina and alumina alone. The immobilisation of plant gall increased the removal percentages from 60-70% to 90-95%. The proposed methods (AOPs and biosorption) have both advantages and disadvantages compared to each other.