Photocatalytic removal of an azo dye from solutions using ZnO and modified ZnO: Benzoic acid azo dye as a model

Abstract

The effects of azo dyes, a severe water pollution source, on the ecosystem and public health have been widely studied, and more studies were made to remove these dyes from water using chemical, biological, electrochemical and physicochemical methods. This study relies on the photocatalytic degradation process as a clean method to clean water from azo dyes. The 4-((2-methyl-1-hydroxy naphthalene-1-yl) diazenyl) benzoic acid azo dye was used as a model dye in this study and prepared from a coupling reaction of p-aminobenzoic acid with 2-methylnaphthol. The photocatalytic degradation of this dye has been carried out using ZnO and modified ZnO. The dye removal was tested at various weights of ZnO and modified ZnO, different concentrations of the dye under constant light irradiation by using a 250 watts UV lamp. The results showed the dye removal by the modified (ZnO) was 92.4%, which is higher than the removal efficiency by the unmodified ZnO (87.51%). In conclusion, the results of this study showed that modified ZnO removes a high percentage of the dyes; therefore, it is recommended to use it to remove other common pollutants in the Iraqi rivers, such as phosphate and turbidity.