本试验采用P-25TiO2光催化剂,对4-氯苯甲酸钠的光催化氧化降解及污染物初始浓度、催化剂投加量和入射光强等因素的影响进行了研究。研究发现污染物初始降解速率与其初始浓度的关系遵循Langmuir-Hinshelwood模式,其中半饱和浓度常数Ks不仅是催化剂和污染物种类的函数,而且也是入射光强的函数。催化剂投加量存在一限值,当低于此限值时,污染物降解速率由于催化剂浓度的不足受到影响而下降;当高于此限值时,污染物降解速率受催化剂投加量的影响变小。在本试验4-CBA-Na浓度为0.15～0.6mmol/L时该催化剂限值浓度大约为0.4g/L。在入射光强为1～7mW/cm2和催化剂浓度为0.4g/L下,污染物降解速率与光强成0.67次幂关系,经估算其量子效率为6.3%。%Photocatalytic degradation of sodium 4-chlorobenzoate (4-CBA-Na)as a model pollutant with titanium P-25 was studied. The dependence of the initial photocatalytic degradation rate on the organic concentration, catalyst dosage and incident light intensity was investigated. The relationship between the degradation rate and the initial organic concentration was found to follow Langmuir-Hinshelwood model, a parameter of which, the half saturation concentration, Ks depends not only on the characteristics of catalyst and organic substance but also on the incident light intensity. There existed a critical catalyst dosage, which was around 0.4g/L at organic concentration of 0.15 to 0.6mmol/L. When the catalyst dosage was below or beyond the critical value, the organic degradation rate was decreased owing to insufficient catalyst concentration or leveled off. The incident light intensity within the range of 1～7mW/cm2 showed a 0.67 power effect on the degradation rate. The quantum yield in the photocatalytic degradation was estimated to be 6.3%.
展开▼
