燃煤烟气中多环芳烃(PAHs)光化学降解的研究

STUDY ON PHOTOCHEMICAL DEGRADATION OF POLYCYCLIC AROMATIC HYDROCARBONS(PAHs)FROM COAL-FIRED FLUE GAS

研究了各种条件下,燃煤烟气中多环芳烃(PAHs)的光化学降解。实验结果表明,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。还提出了由烟气中水蒸气产生的气态OH自由基以及未燃尽烃类自由基与激发态PAHs碰撞导致发生PAHs污染物光化学降解的反应机理。

In this paper, photochemical degradation of polyeyclic aromatic hydrocarbons （PAHs） from coal - fired flue gas under various conditions, including temperature, moisture content, light source, light intensity and exposure time, was studied. Experimental results showed that, for a fluorescent lamp used as the light source, degradation of PAils was increased with increasing light intensity, exposure time, temperature or moisture content. It could be deduced that in the summer with high temperature, high moisture and long sunshine, PAHs degrade totally within several hours, whilst 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 and unburned hydrocarbon free - groups with excited- state PAH pollutants was also pro- pond.