Photo Degradation and Removal of Malachite Green from Water, Using Nano Titanium Dioxide Photo Catalyst

Malachite greenis an extensively used biocide in the aquaculture industry, and is highly effective against important protozoal and fungal infections. It is also used as a food coloring agent, food additive, and medical disinfectant as well as a dye in the silk, wool, jute, leather, cotton, paper, and acrylic industries. Therefore, the elimination of malachite green in wastewater of aquaculture and textile, paper and acrylic industries is essential in order to prevent its adverse effects on aquatic organisms. In this study, degradation of malachite green with titanium dioxide nanoparticles (TiO2 NPs) under UV light was investigated.

For this reason, the effects of parameters such as different concentrations of malachite green (3.5, 7 and 14 mg L-1) and the Nano-catalyst concentrations (1.30, 2.60, and 5.20 mg) in constant temperature (25°C) and constant UV intensity (12 W, 230 V, 50 Hz) during 180 minutes were studied.

The best degradation rate of malachite green was found in the concentration of 3.5 mg L-1 malachite green, pH: 9, and 2.60 mg of TiO2 NPs. Although with an increase in titanium dioxide nanoparticles the efficiency and removal rate of malachite green increased, the increase in the photo catalyst had no effects on increasing the efficiency of photo degradation. An increase in pH (9) may improve the removal rate of malachite green through increasing free radicals. An increase in the initial concentration of malachite green decreased the efficiency and removal rate of malachite green.

Therefore, the photo degradation of malachite green in the presence of TiO2 NPs photo catalyst could be a function of pH, the initial concentration of malachite green and concentration of TiO2 NPs.