Enhanced photocatalytic reaction and mechanism for treating cyanide-containing wastewater by silicon-based nano-titania

Abstract The treatment of cyanide-containing wastewater is very important for the sustainable development of gold industry. Treating wastewater by nano-titania (nano-TiO2) has the advantage of adsorbing heavy metals and catalyzing the decomposition of cyanogen simultaneously. Since the catalysis is limited by solid-liquid diphase system, the photocatalytic and adsorption efficiency is relatively low. This study aimed to enhance catalytic process based on silicon-based nano-TiO2 composite functional material to treat deeply cyanide-containing wastewater. The characteristics of the silicon-based nano-TiO2 material were studied by Brunner−Emmet−Teller (BET) and field emission scanning electron microscopy (FESEM)/ energy dispersive spectrometer (EDS), which indicated that the material has excellent dispersibility and large specific surface area(146.6±2.4 m2·g−1). Further, the comparison of the treatment effects of cyanide wastewater with pure nano-TiO2 and silicon-based nano-TiO2 material demonstrates that the latter is more effective on cyanide degradation. Almost 99.8% of cyanide degradation was achieved by silicon-based nano-TiO2 material under light irradiation within 135 min. The mechanism and X-ray photoelectron spectroscopy (XPS) analysis. It was found that the final decompositions of Copper cyanide complex and zinc cyanide complex are CO2, NO2, Cu2+ and Zn2+.