硝基多环芳烃在雪中的光解反应动力学
发布时间：2018-01-01 23:32
本文关键词：硝基多环芳烃在雪中的光解反应动力学 出处：《吉林建筑大学》2017年硕士论文 论文类型：学位论文
【摘要】：雪是极地地区和高海拔地区生态系统的重要组成部分,降雪过程中,大气污染物可通过干湿沉降等方式进入雪中,也可以被沉降后的积雪吸附,使得雪成为大气污染物的重要储存库。从20世纪末期开始,研究人员陆续在极地和高海拔地区检测出多种持久性有机污染物(Persistent organic pollutants,POPs)。POPs具有持久性、半挥发性及高毒性等特性,可长距离的迁移,对人类健康与环境安全造成持久性危害。据了解,雪中的POPs可通过挥发作用进入大气,也可以通过光化学作用进行转化,且光化学作用可能将POPs转化成持久性更强、毒性更大的产物。硝基多环芳烃(Nitro polycyclic aromatic hydrocarbons,NPAHs)是一类具有直接致突变和致癌活性的污染物,其致突变性和致癌性远远高于其母体多环芳烃,对环境及人体健康造成了极大威胁,近年来受到研究人员的广泛关注。据了解,含有四个苯环的NPAHs的致突变性最高,而含有两个硝基的NPAHs比单硝基的NPAHs活性要高,汽车尾气中含量最高的NPAHs是1-硝基芘(1-nitropyrene,1-NP),而1,8-二硝基芘(1,8-dinitropyrene,1,8-DNP)是目前报道过的致突变性最高的化合物。在温度较低的冰雪环境中,常规的化学反应较弱,光化学作用是NPAHs在环境中迁移转化的重要途径。研究者们对大气、固体表面和有机溶剂中NPAHs光化学的研究较多,而对水和雪中NPAHs光化学的研究很少。因此,本论文建立了NPAHs的定量分析方法,并通过室内模拟实验,对比研究了紫外光作用下1-NP和1,8-DNP在水和雪中的光转化规律,建立了1-NP和1,8-dnp在水和雪中的直接光解动力学,并考察了光敏剂(h2o2、no2-、no3-)、bc、fenton、ph值及助溶剂等对npahs光解的影响。得到的结论如下:一、基于lc-ms/ms的水中痕量npahs的分析方法通过对质谱和色谱条件的优化,采用带有大气压化学电离源(atmosphericpressurechemicalionization,apci)的高效液相色谱-串联质谱(lc-ms/ms)测定水中痕量npahs的含量。结果表明,1-np和1,8-dnp的线性范围分别为0.72~12μg/l和0.48~48μg/l,相关系数r2分别为0.9990和0.9992,回收率分别为97.67%~104.44%和93.33~103.13%,方法检出限(s/n=3)分别为0.21μg/l和0.15μg/l,定量限(s/n=10)分别为0.72μg/l和0.26μg/l。方法具有不需要前处理、操作简便、且灵敏度高等优点,优于其他液相、气相色谱等检测方法。二、紫外光作用下npahs在水中的光解(1)紫外光照射下,1-np和1,8-dnp在水中均可发生光转化反应,并且符合一级动力学方程。(2)随npahs初始浓度的增加,其光解速率变慢;(3)在体系中加入光敏剂(h2o2、no2-和no3-)均促进了水中npahs的光解,且光解速率随光敏剂浓度的增加而变快;(4)fenton对水中npahs光解的影响为先抑制、后促进,且fe2+和h2o2的最佳浓度比为1:3;(5)bc主要通过吸附作用使1,8-dnp从水中去除,光解的贡献几乎可以忽略;(6)酸性条件和碱性条件均促进了水中npahs的光转化,且酸性条件下促进效果更好;(7)助溶剂甲醇促进了水中npahs的光解,且甲醇浓度越高,npahs的光解越快。三、紫外光作用下npahs在雪中的光解(1)紫外光照射下,1-np和1,8-dnp在雪中可发生光转化反应,并且均符合一级动力学方程。(2)随1,8-DNP初始浓度的增加,雪中1,8-DNP光解速率变快;(3)低浓度H_2O_2(50μmol/L)对雪中1,8-DNP光解无影响,高浓度H_2O_2(200μmol/L)促进了雪中1-NP的光解;(4)NO_2~-和NO_3~-均促进了雪中NPAHs的光解;(5)Fenton对雪中1-NP和1,8-DNP光解的影响不显著;(6)BC主要通过吸附作用使1,8-DNP从雪中去除,光解的贡献几乎可以忽略;(7)BC与光敏剂(H_2O_2、NO_3~-和NO_2~-)共同作用的情况下均会促进雪中1,8-DNP的光解,其中BC+NO_2~-对雪中1,8-DNP光解的促进更明显;(8)酸性、碱性条件均促进了雪中1-NP的光解,而酸性条件促进了雪中1,8-DNP的光解,碱性条件抑制了雪中1,8-DNP的光解。
[Abstract]:Snow is an important part of the ecological system of the polar regions and the high altitude, snow process, air pollutants can enter the snow by dry and wet deposition etc., can also be absorbed after the settlement of the snow, the snow has become an important repository of atmospheric pollutants. From the beginning of the end of the twentieth Century, the researchers are in the polar and high altitude areas detection of a variety of persistent organic pollutants (Persistent organic pollutants, POPs.POPs) with persistent, semi volatile and highly toxic properties, can migrate long distances, cause lasting harm to human health and environmental safety. It is understood that the snow POPs can enter the atmosphere through volatilization, can also be carried out by photochemical transformation effect and photochemical effect may be POPs into a more durable, more toxic products. Nitro polycyclic aromatic hydrocarbons (Nitro polycyclic aromatic hydrocarbons, NPAHs) is A class of direct mutagenic and carcinogenic activity of pollutants, the mutagenicity and carcinogenicity of polycyclic aromatic hydrocarbons is much higher than that of its parent, caused a great threat to the environment and human health, have attracted much attention in recent years. It is understood that the mutagenicity of the highest with four benzene rings of NPAHs, which contains two nitro the NPAHs is higher than single nitro NPAHs activity, the content of NPAHs in the automobile exhaust is the highest 1- nitropyrene (1-nitropyrene, 1-NP), and 1,8- two nitropyrene (1,8-dinitropyrene, 1,8-DNP) is caused by mutation of the highest compounds have been reported. In the low temperature environment in the snow, the conventional chemical reaction is weak the photochemical effect, is an important way of migration and transformation of NPAHs in the environment. The researchers studied the solid surface to the atmosphere, and the organic solvent in NPAHs photochemistry, while research on water and snow NPAHs photochemical very little. Therefore, this paper established a method of quantitative analysis of NPAHs, and through the indoor simulation experiment, a comparative study of the effect of UV 1-NP and 1,8-DNP in the water and snow in the light of transformation rules, direct photolysis kinetics of 1-NP and 1,8-dnp in water and snow was established, and the effects of photosensitizer (H2O2, no2-, no3-). BC, Fenton, pH value and effect of CO solvents on the photolysis of NPAHs. The conclusions are as follows: first, the optimization of mass spectrometry and chromatographic conditions through the analysis method of trace NPAHs in water based on lc-ms/ms, with atmospheric pressure chemical ionization source (atmosphericpressurechemicalionization, APCI) by high performance liquid chromatography tandem mass spectrometry (lc-ms/ms) determination of trace NPAHs in water. The results showed that the linear range of 1-NP and 1,8-dnp were 0.72~12 g/l and 0.48~48 g/l, the correlation coefficient R2 were 0.9990 and 0.9992, the recovery rate was 97.67%~104.44% and 93.33~10 3.13%, the limit of detection (s/n=3) were 0.21 g/l and 0.15 g/l, the limit of quantification (s/n=10) were 0.72 g/l and 0.26 g/l. method is not need pretreatment, simple operation, and high sensitivity, better than other liquid chromatography, gas chromatography and other methods. Two, UV photolysis light under the action of NPAHs in water (1) under UV irradiation, 1-NP and 1,8-dnp light conversion reaction in water can be, and in accordance with the first-order kinetic equation. (2) with the increase of initial NPAHs concentration, the photolysis rate slowed down; (3) adding photosensitizer in the system (H2O2, no2- and no3-) were promote the photolysis of NPAHs in water, and the photolysis rate increased with the increase of concentration of the photosensitizer and change rapidly; (4) the effect of Fenton on NPAHs in water photolysis was firstly inhibited, after the promotion, and the optimal concentration of fe2+ and H2O2 is 1:3; (5) BC mainly by adsorption to 1,8-dnp removed from the water, the contribution of photolysis almost can be ignored. 鐣，
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