Photodegradation of Chlorinated Organic Pollutants in Wastewater in the Absence of Dissolved Oxygen

以废水处理为研究对象，研究了紫外光降解水中氯代脂肪族和芳香族有机污染物。本研究的重点是提出一种新的无溶解氧（DO）条件下光降解的化合物的技术。本研究获得的结果如下。(1)紫外光（波长185 nm +254 nm）在无DO条件下照射，可显著加速四氯化碳、氯仿、1，2-二氯乙烷、1，1，1-三氯乙烷和1，1，2-三氯乙烷等结构中只有单键的脂肪族化合物的降解。对于结构中含有双键的四氯乙烯、三氯乙烯和氯苯，去除DO效果不明显。(2)用紫外线（185 nm +254 nm）照射氧饱和的水体，使溶解氧下降。而254 nm的紫外线则没有引起溶解氧的降低。(3)这些结果有力地使我们得出以下结论，光降解下的自由DO。185 nm的紫外线能量足以直接破坏烃类的键。然而，在溶解氧存在下，能量被溶解氧转化为其他物种所消耗。这项研究显示了这种新技术在废水处理中的巨大潜力。

Photodegradation of organic pollutants of chlorinated aliphatic and aromatic hydrocarbons in water by irradiation of ultraviolet aiming a wastewater treatment was studied. The point of this study is to propose a novel technique of photodegradation of the compounds under free of dissolved oxygen (DO). The results obtained by this study are as follows.(1) The irradiation of ultraviolet (wavelength of 185nm + 254nm) without DO remarkably accelerated the degradation rates of aliphatic compounds having only single bond in their structures, such as carbon tetrachloride, chloroform, 1,2-dichloroethane, 1,1,1-trichloroethane, and 1,1,2-trichloroethane. Removing DO was not so effective for tetrachloroethylene, trichloroethylene and chlorobenzene having double bond in their structures.(2) The irradiation of ultraviolet (185nm + 254nm) to water saturated with oxygen caused the decrease of DO. On the other hand ultraviolet of 254nm did not cause such decrease of DO.(3) These results strongly lead us to a following conclusion for photodegradation under free of DO. The energy of ultraviolet of 185nm is strong enough to break the bond of hydrocarbons directly. In the presence of DO, however, the energy is consumed by DO to be converted into other species.This study shows us a high potential of this novel technique for wastewater treatment.