Background and purpose: Malachite green is one of the most widely used dyes in various industries, aquaculture, and fungicides. The residues have adverse effects on environmental and human health and should be removed from the effluent before discharging to the environment. The purpose of this study was to investigate the efficiency of photocatalytic process using halloysite-titanium dioxide nanocomposite in the removal of malachite green from aqueous solutions and the effect of various parameters on the process efficiency.
Materials and methods: This experimental study was performed on a laboratory scale in a discontinuous system. In this process, a 15 W (UV-C) lamp of 26 mm diameter and length of 45 cm and a nanocomposite (halloysite-titanium dioxide) were used. The influence of contact time, nanocomposite dose, dye concentration, and pH of the reaction on the removal efficiency was investigated. The properties of the synthesized nanocomposite were determined by sol-gel method using XRD and SEM techniques. The concentration of malachite green was measured using a UV-VIS spectrophotometer at 619 nm.
Results: The best photocatalytic dye removal efficiency (91.29%) was seen at 3 mg/l dye concentration, pH= 10, contact time= 90 min, and nanocomposite dose= 0.1 g/l.
Conclusion: This study showed that photocatalytic process using nanocomposite (halloysite-titanium dioxide) is efficient in decomposing and removing malachite green.
 

Keywords: malachite green, photocatalytic decomposition, halloysite, titanium dioxide, nanocomposite, wastewater treatment

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