二氧化钛微粒存在下表面活性剂光催化分解机理的研究

半导体微粒子(二氧化钦等)在光照射下产生强烈的氧化能力,可以把水和空气中的许多难分解有毒有机污染物氧化分解为二氧化碳、水等无机物。该方法分解速度快、除净度高,有着很大的应用前景^1~3]。在过去几年里,我们广泛地报导了在二氧化钦半导体微粒子催化下表面活性剂^3,4]、农药^5]氰化物困等环境污染物的光催化分解。烷基、芳香基及含氧碳氢基团可被氧化分解为二氧化碳和水^4];有机化合物中的卤素^5]、磷川、硫^8]氮^9]原子分别被光分解为卤素离子、磷酸根离子、硫酸根、按和硝酸根离子。因多相光催化反应十分复杂,目前对光催化分解过程,特别是中间化合物的生成及其浓度变化了解很少,甚至连光致电子及空穴的反应也并不十分明确。

A STUDY ON MECHANISM OF THE PHOTODEGRADATION OF SURFACTANTS CATALYZED BY TiO2 PARTICLES

The photodegradation of surfactant n-nonylphenylpolyoxyethylen ethers catalyzed by TiO₂ semiconductor particles has been observed. The formation of intermediates of peroxides and formaldehyde was determined in the photocatalytic oxidation process. It was found that the concentrations of both peroxides and formaldehyde formed in the photodegradation process increased with irradiation time to reach a maximum and subsequently decreased with further irradiation except the NPE-50;peroxides achieve the maximum concentration more rapidly than formaldehyde;with increasing the length of polyoxyethylene chain in the NPE structure,the formations of peroxides and formaldehyde increased.The photocatalytic oxidation mechanism is also discussed on the basis of experimental results.