纳米金为表面增强拉曼基底的多环芳烃检测研究

发布时间：2019-03-13 17:05

【摘要】：多环芳烃(PAHs)是持久性有机污染物中危害性很大的一类,传统的检测方法由于预处理时间长和不便于原位检测的缺点不足以满足快速检测需求。新型分析技术中表面增强拉曼(SERS)提供了可用于高灵敏度检测的振动光谱,成为了环境分析领域中新型的检测手段,拥有巨大的应用潜力。本文制备了3种SERS增强基底,对多环芳烃中常见的萘、蒽、菲、芘和它们的混合物进行检测。本文首先以金属溶胶法制备了SERS活性基底并进行了参数优化。通过调节加入柠檬酸钠的量,合成了平均粒径约15~150nm的五种粒径的金溶胶。用这五种粒径的金溶胶作为基底,通过激发光785 nm的液体拉曼系统,检测了对对巯基苯甲酸的检出限均达到10-8 mol/L,并计算了金溶胶的SERS增强因子(EF),其中平均粒径为41nm和72nm的金溶胶特征峰强度较好,与之前的EF计算结果吻合。然后选择粒径为41nm的金溶胶检测10-5mol/L的芘,发现特征峰不明显。通过浓缩的方法增大纳米金密度后,对不同浓度的萘、蒽、菲、芘溶液进行了单独的SERS光谱探测,测得检出限均达到10-7 mol/L。对四种PAHs混合物的检测发现特征峰会由于峰重叠与竞争吸附等关系有所变化和减弱。以不同芘的浓度和特征峰强度为研究对象进行线性拟合,线性相关系数均在0.985以上。可以用于半定量检测。为了进一步提高PAHs的检测灵敏度,本文通过将金溶胶、不同比例甲醇溶胶和检测物混合后将沉积物浓缩烘干的方式,在激发光为633nm的显微拉曼仪上进行了以多环芳烃中芘为检测物的检测。研究了这种检测方式下金溶胶制备的最佳时间为30min。检测的最佳粒径为72 nm。这与之前的液体拉曼检测有所区别,可能与激发光波长、基底的尺寸和形貌有关。本文研究了p H值、氯离子等对纳米粒子的聚集作用,以及聚集作用对SERS检测的影响,通过对比,当p H=12,氯离子的最终浓度为0.75μmol/L时检测效果最好,说明OH-离子和Cl-能更好的促进金溶胶和分析物的聚集。实验用优化条件后的金颗粒基底测定芘的检出限达到了10-8 mol/L。上述第一种方法中,为获得良好的检测效果,需要对刚合成的金溶胶纯化浓缩,增加了制备的复杂性;第二种方法虽然信号得到进一步增强,但是基底的重复性不易保证。因此,论文最后探索性地采用易获得的毛玻璃、砂纸和以砂纸为模板制备的PDMS结构,并在表面溅射金做为SERS的增强基底,用激发光633 nm的显微拉曼系统,检测了它们SERS背景值,并用砂纸、砂纸翻的PDMS和毛玻璃检测了芘。
[Abstract]:Polycyclic aromatic hydrocarbons (PAHs) are one of the most harmful persistent organic pollutants (pops). The traditional detection methods can not meet the needs of rapid detection due to the disadvantages of long pretreatment time and inconvenient in-situ detection. Surface-enhanced Raman (SERS) (SERS) can be used to detect vibration spectra with high sensitivity. It has become a new detection method in the field of environmental analysis and has great potential for application. Three SERS-enhanced substrates were prepared for the determination of naphthalene anthracene phenanthrene pyrene and their mixtures in polycyclic aromatic hydrocarbons (PAHs). In this paper, SERS active substrates were prepared by metal sol method and the parameters were optimized. Five kinds of gold sol with average diameter about 15~150nm were synthesized by adjusting the amount of sodium citrate added. The detection limits of p-mercaptobenzoic acid were all up to 10 渭 8 mol/L, using the gold sol as the substrate and the liquid Raman system with excitation light of 785 nm. The SERS enhancement factor (EF), of the gold sol was calculated. The characteristic peak strength of gold sol with average particle size of 41nm and 72nm is better, which is in good agreement with the previous EF calculation results. Then the pyrene of 10-5mol/L was detected by gold sol with the particle size of 41nm, and the characteristic peak was not obvious. The SERS spectra of naphthalene, anthracene, phenanthrene and pyrene with different concentrations were detected by concentration method. The detection limits were all up to 10 ~ 7 mol/L.. The detection of four PAHs mixtures showed that the characteristic summit changed and weakened due to the relationship between peak overlap and competitive adsorption. The linear correlation coefficients of different pyrene concentration and characteristic peak intensity were above 0.985. It can be used for semi-quantitative detection. In order to further improve the detection sensitivity of PAHs, the sediment was concentrated and dried by mixing gold sol, methanol sol in different proportion with the detector. Pyrene in polycyclic aromatic hydrocarbons (PAHs) was detected by micro-Raman spectroscopy (633nm). The optimal preparation time of gold sol was 30 min. The optimum particle size is 72 nm.. This is different from the previous liquid Raman detection, which may be related to the excitation wavelength, the size and morphology of the substrate. In this paper, the effects of pH value, chloride ion and other ions on the aggregation of nanoparticles and the effect of aggregation on the detection of SERS were studied. By comparison, when the final concentration of chloride ion was 0.75 渭 mol / L, the detection effect was the best. The results show that OH- ion and Cl- can promote the aggregation of gold sol and analyte. The detection limit of pyrene was up to 10 ~ 8 mol/L. by using the optimized conditions for the determination of pyrene on the substrate of gold particles. In the first method, in order to obtain a good detection effect, it is necessary to purify and concentrate the newly synthesized gold sol, which increases the complexity of preparation, and the second method, although the signal is further enhanced, is not easy to guarantee the repeatability of the substrate. Therefore, in the end of the thesis, we use easily obtained wool glass, sandpaper and PDMS structure based on sandpaper as template, and sputtering gold on the surface as the reinforced substrate of SERS. The background values of SERS are measured by using the microscope Raman system of excited light 633 nm. Pyrene was detected by sand paper, PDMS and wool glass.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X830

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