Photodegradation of Organic Pollutants in Wastewater under Free of Dissolved Oxygen

在存在和不存在溶解氧（DO）的情况下，紫外照射对几种有机物质的光降解得到了证明。通过测定降解速率常数来评价DO对光降解的影响。(1)研究了几种苯衍生物在无溶解氧条件下的光降解。取代基对降解速率的影响为：NH_2<OH<CH_3<H<Cl>Br>COOH>NO_2。Cl、Br、COOH衍生物产生苯作为中间化合物。另一方面，NH_2、OH、CH_3在降解过程中没有给苯。很明显，两种衍生物的降解机制是完全不同的。在没有DO的情况下，Cl和Br基团显著提高了它们的降解率，约为3倍。(2)在DO存在和不存在的情况下，紫外照射法对EDTA和EDTA- mn、Zn、Ni螯合物的降解效果不明显。(3)发现Na_2SO_4、K_2SO_4等无机盐对有机材料的紫外光降解有促进作用。

Photodegradation of several organic substances by UV irradiation was demonstrated in the presence and absence of dissolved oxygen (DO). The degradation rate constants were determined to evaluate the effect of DO on the photodegradation.(1)Photodegradation of several benzene derivatives in the absence of dissolved oxygen was performed. The effect of substituent on the degradation rate was, NH_2<OH<CH_3<H<Cl>Br>COOH>NO_2. The Cl, Br, COOH derivatives produced benzene as an intermediate compound. On the other hand, NH_2, OH, CH_3 did not give benzene in their degradation processes. It is clear that the degradation mechanisms are quit different between the two derivative groups. The groups of Cl and Br drastically promoted their degradation rate, about 3 times, in the absence of DO.(2)The UV irradiation method was not effective for the degradation of EDTA and EDTA-Mn, Zn, Ni chelates in the presence and absence of DO.(3)It was found that inorganic salts, such as Na_2SO_4, K_2SO_4 promote the photo-degradation of organic materials by UV.