Cyanide Removal Efficiency of Photocatalytic Nanoparticles Stabilized on Glass Microbeads Under Sun Irradiation

This paper investigates cyanide photodestruction (at pH 9) using the S, N-TiO2 photocatalyst synthesized by the sol-gel method and stabilized on glass microbeads. The main raw materials were thiourea, as a source of N and S, and tetra butyl ortho titanate. The effects of S and N doses, visible light (a 400W light), sunlight, irradiation time, and different initial cyanide concentrations (50, 100, 200, and 300 ppm) were studied on cyanide photodestruction. Cyanide concentration was measured by the titration method and the photocatalyst film was characterized by X-ray diffraction (XRD), UV-Vis diffuse reflection spectroscopy (DRS), Scanning Electron Microscopy (SEM), and Energy dispersive X-ray (EDX) analysis. XRD patterns and SEM images were used to determine the nanoparticle size of the photocatalyst on glass microbeads. EDX and DRS analyses confirmed the presence of S and N as well as the activity of the photocatalyst in the visible region, respectively. The S, N-TiO2 film with 0.25 g Thiuourea proved to be the best cyanide photodestruction agent in the visible light. Based on the results obtained, S, N-TiO2/ glass microbead was capable of destroying cyanide (50 ppm) by up to 94% in the visible light and by approximately 100% in the sunlight. The results also indicated that S, N-Tio2/scoria stone was capable of destroying cyanide by 85% in the visible light and by 94% in the sunlight within 4 h. The reaction kinetic for all cyanide concentrations and two photocatalyst substrates were described by a first order equation. Finally, it was concluded that the S, N-TiO2 stabilized on glass microbeads could be effectively used as a new method for treating wastewater containing free cyanide under the sunlight.