Photocatalytic decolourization of a new water-insoluble organic dye based on phenothiazine by ZnO and TiO2 nanoparticles

Abstract

A new water-insoluble organic dye, namely, 2-((10-decyl-10H-phenothiazin-3-yl)methylene)malononitrile, was synthesized and fully characterized. It was envisioned that photocatalytic decolourization of a dye-containing long chain would pave the way for the photocatalytic remediation of wastewater containing toxic hydrophobic organic pollutants. Two commercially available nanoparticles, ZnO and TiO2, were selected, and their photocatalytic decolourization of the dye from aqueous medium were compared. The black UV light irradiation of the colored samples in the presence of TiO2 (P25) or ZnO resulted in their decolourization and the photocatalytic activity observed for TiO2 (P25) was better than that of ZnO. The kinetic of decolourization indicated that the process was first-order from which the rate constant was calculated. Also, the effect of pHs on the kinetic of decolourization revealed a negligible effect, indicating that the pH, although it affects the catalysts but has no effect on the organic-based hydrophobic dye and thus no effect on the photocatalytic process. Keywords: Phenothiazine, Photocatalysis, Water-insoluble dye, Photocatalytic decolourization, TiO2, ZnO