Photocatalytic decomposition of cyanide in pure water by biphasic titanium dioxide nanoparticles

Abstract

Cyanide found in industrial wastes is among the critical environmental issues. The purpose of this research was to investigate the effects of various operating parameters, such as cyanide initial concentration, hydrogen peroxide dosage, amount of catalyst, UV light intensity and acidity on the photocatalytic degradation of cyanide using TiO₂ nanoparticles. The characterization of synthesized nanoparticles was also conducted using X-ray diffraction, and transmission electron microscopy techniques. Biphasic form of TiO₂ nanoparticles indicated the maximum removal yield and complete degradation of cyanide. Increase in initial concentration of cyanide causes decrease in removal yield. The complete removal of cyanide was achieved with dose of 3 mg L⁻¹ in 45 min, while lasting for 90 min without H₂O₂ degradation process. In addition, at pH 11 and catalyst content of 1 g L⁻¹, the maximum cyanide removal was observed. The efficiency of cyanide removal can be affected by various operating parameters. Increasing cyanide concentration resulted in decreasing removal rate of cyanide, as for concentrations 15 and 100 ppm cyanide was completely degraded during 10 and 90 min, respectively. Moreover, for cyanide degradation, the optimum TiO₂ content and pH were determined as 1 g L⁻¹ and 11, respectively. Furthermore, the efficiency of removal process corresponds with the increased UV lamp irradiation and H₂O₂ dosage.

Keywords:

• Cyanide
• TiO₂ nanoparticles
• Photocatalytic decomposition
• Hydrogen peroxide dosage

Acknowledgments

The authors would like to thank the management and authorities of Tarbiat Modares University (TMU, Iran Nanotechnology Initiative Council (INIC) and Qaemshahr Branch of Young Researchers Club for their constant support and encouragement.