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

以废水处理为目标，研究了紫外照射光降解水中氯代脂肪烃和芳香烃有机污染物。本研究的重点是提出一种在无溶解氧（DO）条件下光降解化合物的新技术。本研究的结果如下：(1)不含DO的紫外（波长185nm + 254nm）辐照显著加快了四氯化碳、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单键脂肪族化合物的降解速度。对结构中含有双键的四氯乙烯、三氯乙烯和氯苯，脱除DO效果不明显。(2)紫外（185nm + 254nm）照射饱和氧水，使DO降低。另一方面，254nm的紫外线没有引起DO的降低。(3)这些结果有力地证明了无DO条件下的光降解。185nm的紫外线能量足以直接破坏碳氢化合物的化学键。然而，在DO存在的情况下，能量被DO消耗并转化为其他物质。这项研究显示了这种新型废水处理技术的巨大潜力。

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.