【作者】 陈忠良；

【导师】 宋启军；

【作者基本信息】 江南大学 ， 分析化学， 2008， 硕士

【摘要】 三氯生(2,4,4’-三氯-2’-羟基二苯醚)是一种国际上流行的广谱高效抗菌剂。由于三氯生的广泛使用,它引起的负面环境问题受到普遍关注。本文首先利用高效液相色谱法对日化产品牙膏和洗手液中的三氯生含量进行分析,并同时对其可能产生的有害物质进行检测。抽样调查了市场上120种牙膏,并对其中22个品牌的28种牙膏进行了三氯生的含量检测,结果发现各品牌牙膏中三氯生的含量均不相同,且同一品牌不同种类的三氯生含量也不一样。随机对市场上的四种抗菌洗手液检测后发现三氯生含量都在0.2%左右。上述测定结果表明两种日化产品中的三氯生含量均符合国家标准。本文进一步采用二噁英标准品,以标准对照(保留时间)及标准加入法进行检测,在牙膏中均未发现有此类物质存在。考虑到三氯生可能对环境带来的负面问题,本文还对太湖水中的三氯生及其它氯代酚含量进行了分析。水样经沉淀、过滤和富集浓缩后进行三氯生、2,4-二氯苯酚、2,4,6-三氯苯酚和五氯酚的检测分析,均未发现有上述氯代酚类物质。在上述工作的基础上,本文对三氯生的光降解条件及过程进行研究。三氯生水溶液在紫外光下的降解过程满足动力学一级反应。同时发现,在pH8.7条件下三氯生降解产生7种聚合物,这些物质在紫外光照射下具有一定的稳定性。三氯生的水溶液比其醇溶液的降解更为明显。在表面活性剂存在下,三氯生的降解比在纯水溶液中困难,且不同类型的表面活性剂对三氯生的降解影响各不相同。在pH8.7,非离子表面活性剂对三氯生的保护能力比离子型表面活性剂强,而在pH10.5,它对三氯生的保护能力则远远下降。表面活性剂的浓度对三氯生的降解影响也不同,对于曲拉通-100(OP)而言,其浓度越大对光降解的影响越明显。通过对表面活性剂不同类型、pH及浓度的考查,得出如下结论,表面活性剂对三氯生溶液光降解的影响主要依赖以下几个方面:(1)表面活性剂的种类,对于非极性的物质,非离子型表面活性剂的影响较大;(2)表面活性剂自身的结构特点,表面活性剂中若存在苯环、杂环等具有紫外吸收的结构,那它在光照过程中必然会吸收一部分能量,从而间接的影响三氯生的光降解;(3)物质的分子状态,当物质处于不同的分子状态,表面活性剂对其作用的能力有所不同,从而会影响光降解进行的程度。最后我们还对三氯生的降解机理展开了研究。其中,产物分析主要利用GC-MS和LC-MS来完成。利用GC-MS通过标准谱图库匹配和实验标准品对照对光降解产物中的2,4-二氯苯酚,2,8-DCDD进行了确证。在pH8.7条件下产生的光聚合物质则主用利用LC-MS来对其进行结构定性。利用氯的同位素丰度来计算各个聚合物的氯原子个数,并以此来推测物质的结构。所测到的聚合物均为二聚或三聚体,同时也发现三氯生在聚合的过程中存在脱氯过程。4,4’-二氯-2-羟基二苯醚就是三氯生在紫外光照射下脱氯产生。三氯生在UVB光照的过程中,其反应的动力学途径可分为以下四个部分:(1)C-O键的断裂;(2)脱氯反应;(3)光聚合过程;(4)环化反应。更多还原

【Abstract】 Triclosan, 5-chloro-2-(2,4-dichlorophenoxy) phenol, is a popular antibacterial agent which has evoked a great deal concerns on its environmental fate due to its widely applications. Determination of the triclosan content in both toothpastes and hand lotions was conducted by using high performance liquid chromatography. Meanwhile, the potential unsafe compounds were analysed by comparing with the retention time of the standards of dibenzo-p-dioxins. Standards addition method was chosen as a detection means. 28 toothpastes in the market were examined in this paper and it was found that the contents of triclosan in every toothpaste sample were different, even for the same brand sample. The results also revealed that the contents of triclosan in all the tested samples are in accordance with the international standard. After examination of the potential harzardous materials related with the triclosan, no dibenzo-p-dioxins or other chlorophenols were detected in toothpaste samples. To exam the potential effluent of chlorophenols into environment, the water samples of Taihu lake were analysed after precipitation, filtration and concentration, no triclosan or other related chlorophenols were detectable.On the basis of the above work, the processes of the photodegradation and the influence factors were also studied. The degradation of triclosan under UVB irradiation followed first-order kinetics. There were 7 photoproducts produced at pH8.7, and these photoproducts exhibit some extent of stability to further photodegradation. It was also found that triclosan is more liable to photodegradation in aqueous solution when compared with that of in organic solvent, such as ethanol. The effect of surfactants on the photodegradation was also investigated. In the presence of surfactants, triclosan was more resistant to photodegradation compared with their absence. Non-ionic surfactant, Triton X-100, exhibits strongest shielding effect on the triclosan photodegradation among the surfactants tested. And this effect was more pronounced when the photodegradation was carried out at pH 8.7 comparing with that at pH10.5. In general, the shielding effect is increasing with the increase of surfactant concentrations. After considering surfactant types, pH and concentrations, it was concluded the surfactant influences were dependant on the following aspects: the first was types of surfactant. Non-ion surfactant has more protective or shielding effects for non-polar compounds; the second was the structure of the surfactant. The one which include the phenyl composition in its structure adsorb the ultraviolet radiation during the degradation process would have more pronounced shielding effects on the the photodegradation. The third factor is that the surfactant effect also depends on the forms of a molecule, i.e., the shielding effect of a surfactant on a molecule and its effectiveness is a function of solution pH, as different pH would lead to a different extent of a triclosan ionization, hence the charge possess by it.Finally, photodegradation mechanism of the triclosan was investigated. The photoproducts was analysed by the LC-MS and GC-MS. 2,4-dichlorophenol and 2,8-DCDD was confirmed by matching with the standards of the corresponding materials. The photopolymerizaiton products was analysed by the LC-MS. The numbers of the chlorine atom in photopolyerization products was estimated by the ratio of the two isotopes of chlorine atom, and hence the structures of the photoproducts could be duduced. All of the polymerized products were dimmers or trimers. Dechlorination takes place during the photo reaction process. For example, 5-chloro-2- (4-dichlorophenoxy) phenol was a result of dechlorination. Four main routes were proposed in the triclsoan photo-reaction process under UVB irradiation, namely homolytic scission of ether bond, dechlorination, ring closure and photo-polymerization.更多还原