紫外光在臭氧降解不同有机物过程中的协同作用

利用O3／UV分别对与臭氧有不同反应活性的对氯苯酚、硝基苯、乙酸和草酸进行了降解试验，结果表明，UV与臭氧化降解的协同作用与目标有机物本身的性质有很大关系，在本实验条件下，UV与臭氧的联用反而降低了对氯苯酚的臭氧化降解效率，30min后体系的TOC去除率仅有59％，而单独臭氧化TOC的去除率达到了66％；对硝基苯和草酸而言，UV均明显地提高了臭氧的降解效率，40min时两者TOC的去除率分别为44％和90％，比单独臭氧化处理分别高出了6％和33％；但是，O3／UV对乙酸几乎无降解活性．在这4种有机物的单独臭氧化降解过程中，除对氯苯酚外，水中均可检测到溶解臭氧．以上的实验结果表明，目标有机物对紫外光的吸收及单独臭氧化过程水中溶解臭氧的存在是O3／UV降解效率提高的必要条件．除UV对目标有机物的活化作用外，降解过程的中间产物H2O2也是O3／UV降解效率提高的一个重要因素，UV分解溶解臭氧在此过程可能仅起了辅助作用。

The synergetic action of UV in the ozonation of different organics

Degradation of different organics such as p-chlorophenol(pCP), nitrobenzene(NB), acetic acid(ACA) and oxalic acid(OA) by O_3/UV were studied. The experimental results showed that synergetic action of UV and ozonation of organic was dependent on the property of organic itself. Under the experimental conditions, the TOC removal rate of pCP degraded by O_3/UV (59% in 30min) was lower than that of ozonation alone (66% in 30min); when the degraded organics were NB and OA, the combination UV with ozone could improve the degradation efficiencies obviously. For example, the TOC removal rates of NB and OA degraded by O_3/UV were 44% and 90%, respectively; and the enhancements of TOC removal rates reached 6% for NB and 33% for OA,respectively. O_3/UV could not improve the TOC removal rate compared with ozonation alone when ACA was degraded. Except for pCP, dissolved ozone could be detected in water during ozonation of the other three organics. The experimental results indicated that organics with UV adsorption and existed ozone oxidation in water were the necessary conditions for O_3/UV to improve the degradation efficiency. Except the activation of organics by UV, the by-product H_2O_2 was also an important factor for the enhancement of degradation efficiency of O_3/UV. The decomposition of dissolved ozone promoted by UV played possibly only an assistant role in this process.