Investigation on the Removal of Malachite Green from Aqueous Solutions Using Photocatalysis of Titanium Dioxide and Zinc Oxide Nanoparticles

Malachite green color has been extensively used in aquaculture industry around the world. The drainage of colored wastewater containing malachite green to aquatic ecosystems has created very serious risks for human health and the environment. The purpose of this study was to investigate the removal of green malachite from aqueous solutions using photocatalysis of titanium dioxide (TiO2) and zinc oxide (ZnO) nanoparticles under the influence of ultraviolet (UV) radiation.

This study was carried out in laboratory scale and in discontinuous system using a photocatalysis process with radiation source of two UV lamps with a power consumption of 12 watts. Also, the impact of some factors including pH, nanoparticle content, malachite green concentration and contact time were investigated in green malachite removal from aqueous solutions.

The results showed that the highest percentage of malachite green removal for titanium dioxide nanoparticle was 90.51% in malachite green concentration of 3.5 mg/l, pH 9, nanoparticle concentration of 5.2 mg/l and 180 minutes. Also, this value for zinc oxide nanoparticle was 91.23% in malachite green concentration of 14 mg/l, pH 9, nanoparticle concentration of 2.6 mg/l and 180 minutes.

According to the results of present study, the photocatalysis method under the influence of ultraviolet irradiation and two nanoparticles of titanium dioxide and zinc oxide, was a function of pH, contact time and the concentrations of malachite green and nanoparticles. It can be concluded that this method was a suitable method for removing malachite green from aqueous solutions.