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臭氧氧化过程中羟基自由基的氧化性能的研究

Oxidation Susceptibility of Hydroxyl Radical during Ozonation

【作者】 李进

【导师】 胡翔;

【作者基本信息】 北京化工大学 , 环境工程, 2007, 硕士

【摘要】 对氯苯甲酸长期以来被用作羟基自由基检测的目标化合物。试验发现以对氯苯甲酸作为目标化合物会带来测量误差,因而选取多种结构不同的有机化合物进行实验以寻找适合作为新的目标化合物的有机物。采用不同的氧化方式,对中间产物进行检测,从而分析可能的氧化途径,及避免不良副产物的出现。针对毒性中间产物甲醛进行了研究。主要结果如下:通过大量实验验证,得出了两种适合作为羟基自由基目标化合物的有机物——丁二酸和丙二酸。它们无毒无害,是常见的二元羧酸。使用丁二酸作为目标化合物,在臭氧氧化氯酚的过程中,利用离子色谱检测水样中丁二酸的浓度变化情况。计算得出了羟基自由基的浓度变化情况。分别采用臭氧单独氧化和臭氧/羟基自由基混合氧化方式氧化壬基酚的水溶液。臭氧分子单独氧化和臭氧/羟基自由基联合氧化均能有效降解壬基酚,在设定氧化时间内均能完全去除任基酚。羟基自由基能极大地提高臭氧氧化壬基酚的经济性。混合氧化方式下的氧化程度高于单独臭氧分子氧化。采用腐殖酸和葡萄糖配水模拟自然水体进行氧化,以丁二酸和丙二酸作为目标物,发现葡萄糖没有明显的抑制或促进作用,而腐殖酸会促进羟基自由基的生成。鉴于中间产物甲醛的环境毒性,以甲醛为对象进行了实验。分别从污染物结构、氧化方式和氧化条件对甲醛产生量的影响进行实验。苯环上不同的取代基会影响甲醛的产量,而对于单烯烃来说,α-C上连接的基团对甲醛产量的影响更大;饱和链烃的甲醛产生量很少,可以忽略不计。以丙烯酸溶液为氧化对象,甲醛浓度变化表现为先增后减,出现峰值。增大进气流量会提高丙烯酸溶液的初始产甲醛速率,使甲醛浓度的峰值减小并提前出现;提高气态臭氧浓度产生类似的效果。·OH的增加有利于壬基酚和水杨酸的开环,从而形成更多的中间产物;而C=C结构更有利于O3分子的加成反应,·OH浓度的增加则提高了矿化率。

【Abstract】 Parachlorobenzoic-acid has long been used to measure the hydroxyl radical as probe compound. It was found to bring error when Parachlorobenzoic-acid is used to be the target, so to choose several organic compounds with different structures for studying in order to find some suitable new compounds. Intermediates in different oxidizing method were detected so as to analyze the possible oxidative pathway and avoid the bad byproducts. Whereas the environmental toxicity of the intermediate formaldehyde, which was studied as object. Following results have been obtained:Succinic acid and malonic acid were found to be suit for target after a lot experiments. They are non-toxic compounds and harmlessness that are familiar binary carboxylic acids. Succinic acid was used as target during ozonation of chlorophenol, whose concentration was measured by ion chromatography. Variation of concentration of hydroxyl radical was computed.Oxidation by ozone alone and mixed oxidation by ozone/hydroxyl radicals were taken individually in ozonation of solution of nonylphenol. Both could degraded nonylphenol effectively, nonylphenol was wiped off in the setting time. Hydroxyl radicals could increase the economic efficiency hugely during ozonation of nonylphenol. Mixed ozonation has higher degree of oxidation than ozonation by ozone alone.Humic acid and glucose were used to simulate the natural water to be oxidized. Take Succinic acid and malonic acid as target, it is found that glucose didn’t restrain producing hydroxyl radicals or accelerate to product but humic acid would accelerate to produce hydroxyl radicals.Experiments about effect of yield of formaldehyde cause by different pollutants structure、oxidative pathway and oxidative conditions were done. Benzene with different substituents in the ring would affect the yield of formaldehyde, especially for monoolefin, the group connected to theα-C would affect more seriously. The yield of formaldehyde of aliphatic saturated hydrocarbon was a fat lot which could be neglected. Take crylic acid solution as object, the concentration of formaldehyde showed increasing followed decreasing with a peak. When augment the inlet flux, the original yield rate of formaldehyde would increase during oxidizing crylic acid solution, and the peak value of concentration of formaldehyde would decrease and bring forward. So did angment of concentration of gaseous ozone. Augment of hydroxyl radicals would be propitious to ringopening of nonylphenol and salicylic acid so as to yield more intermediate product; C=C structure would be propitious to addition reaction of ozone, and the augment of hydroxyl radicals increased percent mineralization.

【关键词】 臭氧羟基自由基甲醛目标化合物
【Key words】 OzoneHydroxyl radicalFormaldehydeProbe compound
  • 【分类号】X132
  • 【被引频次】4
  • 【下载频次】1013
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