Sol–gel synthesis of titania–silica photocatalyst for cyanide photodegradation

The results of a laboratory-scale study of an environmentally friendly water treatment method are presented, where the cyanide was removed by photocatalytic process. TiO2–SiO2 aerogel as photocatalyst has been prepared via sol–gel technique. Several factors were studied in order to find the conditions that could be used to synthesize this photocatalyst for optimum degradation of the cyanide pollutant in aqueous solutions. Best degradation was obtained by TiO2–SiO2 aerogel prepared by using a molar ratio of Ti:Si equivalent to 6:1. In addition, the molar ratios of other reactants such as TEOS:H2O:C2H5OH:HNO3 were taken as 1:8:10:0.25. These chemicals were reacted for 90 min at 25 °C. The produced gel was supercritical dried at 105 bar and 295 °C. Under the best conditions, TiO2–SiO2 aerogel, of a specific surface area of 850 m2/g, resulted in cyanide removal efficiency of 98.74%. Details of the synthesis procedure and results of the characterization studies of the produced gel are presented in this paper.