基于功能化石墨烯富集和检测水及大米中的汞形态

发布时间：2018-04-04 16:12

本文选题：功能化石墨烯　切入点：类浊点萃取　出处：《山东农业大学》2017年硕士论文

【摘要】：汞及其化合物是广泛存在于水体和食物中的一类有毒的重金属污染物,它可以通过食物链在人体内富集,危及人类健康。汞的毒性与其化学形态息息相关,有机汞的毒性远远高于无机汞。然而,自然界的大多数的汞形态可以通过生物地球化学反应转化成毒性最大的甲基汞,特别是在水生环境中。因此,总汞的检测已经不能充分揭示汞及其化合物的生物有效性和毒性,汞形态分析对食品安全、人体健康以及相关毒理研究具有重要的意义。水体及大米中的汞污染一直受到人们的广泛关注。但是,由于其含量较低,易受基质干扰,汞形态分析方法的建立十分必要。本研究制备了两种新型功能化石墨烯材料作为汞形态的高效吸附剂进行样品前处理,结合高效液相色谱-电感耦合等离子质谱(HPLC-ICP-MS)开发富集和检测汞形态的新方法,并进行一系列的方法学验证。该方法成功地应用于实际水样和大米中汞形态的检测,并探讨了相关吸附机理。主要内容如下:1.利用氧化石墨烯(GO)进行有针对性地直接巯基化:氢溴酸与GO表面羟基和环氧基发生亲核取代和加成反应,同时高温处理造成脱水和局部脱溴;随后,含有亲核硫反应中心的硫脲与溴基作用生成异硫脲盐;碱处理水解生成直接巯基化石墨烯(G-SH)。利用透射电子显微镜(TEM)、傅里叶变换红外光谱(FT-IR)、X-射线光电子能谱(XPS)等对G-SH进行表征,用作汞形态的高效吸附剂。具有高分散性的G-SH可以形成类似于胶体的稳定均匀的分散溶液,与传统的浊点萃取相似,加入电解质(NaCl)可以引起分散质的聚集,从而分离吸附剂。该研究建立了基于G-SH为高效吸附剂的新型类浊点萃取(CPEL)技术,并结合HPLC-ICP-MS开发了痕量汞形态检测的新方法。本工作优化了影响萃取效果的实验参数,包括pH值、吸附剂的量、萃取时间、NaCl浓度、洗脱液的类型和浓度、干扰离子。在最佳实验条件下,无机汞(IHg)和甲基汞(MMHg)的检出限(3δ)分别为3.8和1.3 ng·L-1,富集因子分别是78和77。该CPEL-HPLC-ICP-MS方法成功地应用于实际水样和大米中的汞形态分析。2.利用氧化石墨烯(GO)、乙酰丙酮铁(Fe(acac)3)和乙二胺(EDA)在高温高压条件下,一步合成磁性还原氧化石墨烯(rGO-Fe3O4)。由于rGO表面氨基和Fe3O4NPs之间的共价相互作用,合成的rGO-Fe3O4具有较高的稳定性,并且Fe3O4NPs的尺寸分布和覆盖密度可以通过改变GO和Fe(acac)3的初始质量比控制。双硫腙作为高效的汞螯合剂与具有较高暴露面积的GO表面通过π-π相互作用简易结合形成双硫腙功能化磁性石墨烯(D@rGO-Fe3O4)。利用透射电子显微镜(TEM)、X-射线衍射光电子能谱(XPS)、振动样品磁强计(VSM)等进行表征后,将其作为高效的磁性吸附剂,开发了磁性固相萃取技术(MSPE)结合HPLC-ICP-MS检测痕量汞形态的新方法。对相关实验条件进行了优化,包括吸附剂的原料与比例、pH值、萃取时间、洗脱液的类型和浓度、洗脱时间、干扰离子。在最优实验条件下,我们对MSPE-HPLCICP-MS方法进行了方法学验证和实际水样及大米的分析。无机汞(IHg)和甲基汞(MMHg)的检出限(3δ)分别为0.48和0.17 ng·L-1,富集因子分别是400和380。相比于以前报道的检测方法,该方法具有较便捷的前处理以及更高的灵敏度。
[Abstract]:Mercury and its compounds are widely present in a class of toxic heavy metal pollutants in water and food, it can be enriched through the food chain in the human body, endangering human health. Is closely related to the toxicity of mercury and speciation, the toxicity of organic mercury is far higher than that of inorganic mercury. However, since most of the speciation of mercury in natural world can be transformed into methylmercury toxicity the largest biogeochemical reaction, especially in the aquatic environment. Therefore, the detection of total mercury has been unable to fully reveal the bioavailability and toxicity of mercury and its compounds, mercury speciation analysis on food safety, is of great significance to human health and toxicology research. Mercury pollution and rice has been widely people's attention. However, because of its low content, prone to matrix interferences, mercury speciation analysis method. It is necessary to establish two new functions of this research prepared Graphene materials as efficient adsorption of mercury for sample pretreatment, combined with high performance liquid chromatography inductively coupled plasma mass spectrometry (HPLC-ICP-MS) to develop a new method of enrichment and detection of mercury, and a series of methods validation. This method is successfully applied to the actual water and mercury in rice. The adsorption mechanism was discussed. The main contents are as follows: 1. using graphene oxide (GO) for direct sulfhydryl of: hydrobromic acid and GO surface hydroxyl and epoxy nucleophilic substitution and addition reaction, and high temperature treatment caused by dehydration and partial debromination; then, containing thiourea and bromine the role of nucleophilic sulfur reaction center generated isothiuronium salts; alkali hydrolysis treatment of direct thiol graphene (G-SH) by transmission electron microscopy (TEM), Fu Liye transform infrared spectroscopy (FT-IR), X- ray photoelectron spectroscopy (XPS) on G -SH were characterized as efficient adsorbents for mercury speciation. With high dispersion of G-SH can be similar to the colloidal dispersion solution formed stable and uniform, similar to the traditional cloud point extraction, addition of electrolyte (NaCl) can cause dispersion aggregation, thereby separating the adsorbent. The study is established based on G-SH for efficient adsorbent the new class of cloud point extraction (CPEL) technology, a new method and combined with the development of HPLC-ICP-MS detection of Trace Mercury form. The optimized experimental parameters affecting the extraction efficiency, including pH value, adsorbent amount, extraction time, NaCl concentration, type and concentration of eluting liquid, interfering ions at the optimal condition. (IHg), inorganic mercury and methylmercury (MMHg) detection limit (3 D) were 3.8 and 1.3 ng - L-1, the enrichment factor were.2. 78 and 77. of the mercury speciation analysis CPEL-HPLC-ICP-MS method is successfully applied to the actual water samples and in Rice The use of graphene oxide (GO), iron acetylacetonate (Fe (ACAC) 3) and ethylenediamine (EDA) in high temperature and high pressure conditions, one step synthesis of magnetic reduction of graphene oxide (rGO-Fe3O4). Due to the interaction between rGO and Fe3O4NPs on the surface of amino covalent synthesis of rGO-Fe3O4 has high stability, and Fe3O4NPs the size distribution and coverage density can be changed by GO and Fe (ACAC) 3 of the initial mass ratio control. Dithizone as mercury chelator efficient and high surface area exposed to GO through pi pi interactions with simple form of dithizone functional magnetic graphene (D@rGO-Fe3O4) using transmission electron microscopy. (TEM), X- ray photoelectron spectroscopy (XPS), vibrating sample magnetometer (VSM) were characterized after the effective magnetic adsorbent, developed magnetic solid phase extraction (MSPE) combined with HPLC-ICP-MS new form of detection of Trace Mercury Method. The related experimental conditions were optimized, including raw materials and the proportion of adsorbent pH value, extraction time, type and concentration of eluent, elution time and interference ions. Under the optimum conditions, we analyzed the method validation and actual water sample and rice on the MSPE-HPLCICP-MS method of inorganic mercury (. IHg) and methylmercury (MMHg) detection limit (3 D) were 0.48 and 0.17 ng L-1 respectively, the enrichment factor detection method is 400 and 380. compared to the previously reported, this method has the advantages of convenient pretreatment and higher sensitivity.

【学位授予单位】：山东农业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O657.63;TS207.51

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