光化学降解汽车尾气中多环芳烃污染物的研究

研究了不同条件(如温度、水蒸气含量、光源种类、光照强度和照射时间)下,汽车尾气中的多环芳烃(PAHs)的光化学降解。结果表明,采用模拟日光中紫外部分的荧光灯照射,PAHs光解率随光照强度、照射时间、温度和水蒸气含量的增加而增大。由此推断,在夏季高温、潮湿和高日照条件下,PAHs一般在数小时内即全部降解。而在冬季低温、干燥和低日照的气候条件下,PAHs降解速率很小,可在大气中停留较长时间,扩散到较远距离。还提出了由水蒸气产生的气态OH自由基与激发态PAHs碰撞导致发生PAHs光化学降解的反应机理。

Study on photochemical degradation of polycyclic aromatic hydrocarbon pollutants from car exhaust

In this paper,photochemical degradation of polycyclic aromatic hydrocarbons(PAHs) from car exhaust under various conditions,including temperature,moisture content,light source,light intensity and exposure time,was investigated.Experimental results showed that,for a fluorescent lamp used as the light source,degradation of PAHs was increased with increasing light intensity,exposure time,temperature and moisture content.It could be deduced that in the summer with high temperature,high moisture and long sunshine,PAHs degrade totally within several hours,while in the winter with low temperature, low moisture and short sunshine,PAHs degrade slowly and retain in the atmosphere for some time to transfer over a distance.The photochemical degradation mechanism for collision of gaseous free-groups generated from moisture with excited-state PAHs was also proposed.