Preparation Of Lacunaris Coupling CdS/TiO₂ And Photocatalytic Degradation Of Bromamine Acid Aqueous Solution By Sunlight

As world wide enviornment pollution and energy resource crisis are graving gradually today, effective utilization of sunlight to solve pollution problems has became of great interest in many countries. The photocatalytic oxidation technique of TiO₂ has been paid more and more attention for the advantage of less energy cost, mild reaction condition, easy operation, less secondary pollution. The synthesis and applications of photocatalyst with high quantum-efficiency and high activity,which is easy to settle down and separate and can utilize sunlight efficiently, have became hot research topics in the field of environment science.Lacunaris coupling CdS/TiO₂ photocatalyst which can be activated by visible light and easily separated from liquor was prepared by coupling CdS with lacunaris TiO₂ by a sol-gel process. Primary research suggested that the optimal preparation condition is method of calcining-alkali marinating-coupling, calcining temperature 700℃, CdS adulterant proportion3%, and alkali marinating time 20h. The photocatalytic degradation by sunlight was investigated with bromamine acid as pollutant, and the manner of light, initial concentration of the pollutant, dosage of photocatalyst, pH value, sodium chloride concentration and reaction time on the photocatalytic degradation were discussed. The results suggested the optimal degradation condition is point-blank sunlight, dosage of photocatalyst 2g/L , and pH value 10 for the bromamine acid solution of 30mg/L. Meanwhile the existence of a few sodium chloride may enhance chroma degradation, furthermore, the degradation rate decreased distinctly when the concentration of bromamine acid is higher than 50mg/L. Comparing with P25, lacunaris coupling CdS/TiO₂ has better settlement and is easier to be seperated. For the system of degradation using lacunaris coupling CdS/TiO₂ with bromamine acid as pollutant by sunlight, chroma degradation can be discribed by L-H equation, it is zero kinetic reaction. The initial reaction rate constant increases, as initial concentration of the pollutant increasing. When dosage of photocatalyst is 2g/L, the initial reaction rate constant is the fastest. The reaction rate constant in the condition of alkali is faster than in the condition of neutral and acidic. Existence of a few sodium chloride may improve chroma degradation the reaction rate constant.