Study On Preparation Of TiO₂ Photocatalyst And Its Performance On Photocatalytic Degradation Of Cyanide Ion

Cyanide is highly toxic substances.It has been vastly applied to industries of gold extraction,plating,synthetic rubber, synthetic fibre, coking and organic class manufacture etc. As the increasing application, the cyanic waste water has been polluting the environment heavily, which menacing human being's heath and animal's and fish's lives seriously. Treatment of cyanide containing waste water, but the research of decyanidation at present exist limitation, accordingly limit the actual application. So it is important to investigate the cost-effective methods of decyanidation from waste water.In this paper, a detail analyzing and discussion of the decyanidation methods is made , and a method based on TiO₂ and TiO₂-doped catalyst for the photochemical reaction Under UV irradiation to degradate of micro trace cyanide ion in water -method is proposed.The photocatalytic oxidation decomposition of aqueous NaCN solution is taken as reacted model. TiO₂ and TiO₂-doped powder preparated by the method of Sol - Gel is used as catalyst in the photochemical reaction. Under UV irradiation , it can catalytic degradation of CN^-.The main factors of the reaction was discussed in the paper.And the kinetics of the photocatalytic degradation the catalysts of serial TiO₂ . Furthermore, the catalysts were characterized by XRD.The results of the experiment showed:(1) Under UV irradiation TiO₂ has the role of catalytic degradation to CN^- in the solution . In optimal conditions degradation rate is up to 100% .When TiO₂ is preparated by Sol - Gel , the calcination temperature is 600℃, and TiO₂ has the best catalytic effect. At this point its crystalline is anatase and rutile coexistence.(2) The pH of solution, CN^-initial concentration, TiO₂ dosage, reaction time, such as light intensity on photocatalytic reaction was researched by experimental. When the solution's pH is 4 - 10 degradation rate of CN^- s higher and is about 72%.In the same reaction time, degradation rate of CN^- increases with initial concentration of CN^-. when the concentration is 10mg/L ,therate is the maximum,η=77.3%.Experiments shows that if the amount of TiO₂ is appropriate, it shows higher activity.And best amount is 1g/L.The degradation rate of CN^-changes with time, it acts first quickly then slowly. After two hours,the rate is79.7% and eight hours later the rate is 99.2%. The degradation rate can reach 100% underdouble-power UV radiation for 6hours.(3) In this paper, thereaction mechanismof TiO₂ photocatalytic degradation of CN^- was studied. The results show that the reaction follows the first reaction kinetics.(4) Doped TiO₂ and pure TiO₂ has similar performance in photocatalytic degradation CN^-.(5) TiO₂ as a catalyst for photochemical reactioncan be reused.(6) In this paper, a preliminary technology design was made in the usefulness of TiO₂ photocatalytic degradation of CN^-.This method has a high decyanidation capability, and the degradation rate can reach 100% .The obvious characteristic of this method is its high selectivity, it will not react with other ion in waste water in the process of decyanidation, sequential pollution is little. So It will be a kind of prospective method in the decyanidation of waste water.