| 酚类污染物解离态与非解离态光解特性及其速率常数的预测 |
| 摘要点击 2272 全文点击 1953 投稿时间：2009-05-05 修订日期：2009-08-03 |
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| 中文关键词 酚类化合物 直接光解 解离态 非解离态 |
| 英文关键词 phenolic compounds direct photolysis dissociation species non-dissociation species |
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| 中文摘要 |
| 以氙灯为光源模拟太阳光，通过研究不同pH条件下3种酚类污染物直接光解的过程，探讨了酚类污染物的解离对其光解规律的影响，并建立了解离态与非解离态酚类污染物光解速率常数的计算方法及预测模式.结果表明，随着pH从4.0增加到9.0，五氯酚的光解速率常数随之从25.30×10-4 min-1增加到82.90×10-4min-1，而对硝基酚的光解速率常数相应从11.90×10-4 min-1降低到了3.18×10-4 min-1.苯酚的光解趋势与对硝基酚相似，当pH从4.0增加到11.0时，其光解速率常数依次从32.50×10-4 min-1降低至13.40×10-4 min-1.3种酚类化合物的光解总速率常数与解离度之间均满足幂函数变化规律.任意解离度条件下的解离态和非解离态光解速率常数，可根据幂函数的切线方程来确定.解离对酚类物质降解规律的影响主要是通过氧负离子的形成，改变苯环以及其他取代基团的活性而造成的.该研究结果为进一步了解天然水环境中酚类污染物的环境行为提供了理论参考. |
| 英文摘要 |
| Xe lamp was employed to simulate the sunlight as light source to study the direct photolysis of three kinds of phenolic pollutants under different pH values. The effects of the dissociation on their photolysis were investigated,and a calculation method and a forecasting model for the photolysis rate constants under the situation of dissociation and non-dissociation of phenolic pollutants were established. The experiment results showed that the photolysis rate constant of pentachlorophenol (PCP) increased from 25.30×10-4 min-1 to 82.90×10-4 min-1 when pH value varied from 4.0 to 9.0,and that of nitrophenol (PNP) decreased from 11.90×10-4 min-1 to 3.18×10-4 min-1. Similar to the PNP,the photolysis rate constant of phenol decreased from 32.50×10-4 min-1 to 13.40×10-4 min-1 with the pH value increased from 4.0 to 11.0. From analysis of the results,a power function relationships between the total photolysis rate constants (K) and dissociation degrees (α) of these three phenolic compounds could be established. If α had been determined,the dissociation and non-dissociation species photolysis rate constants could be calculated by the tangent equation of the power function. The effect of dissociation on the photolysis should be mainly attributed to the formation of the negative oxygen ions,which led to the changes of the activities of benzene ring and substituent groups. These results will provide theoretical references to further understand environmental behaviors of phenolic compounds in natural waters. |
