四溴双酚A的电化学增敏机制与传感新方法研究

发布时间：2018-08-26 18:08

【摘要】：四溴双酚A (TBBPA)是一种使用非常广泛的溴代阻燃剂,具有内分泌干扰性、免疫毒性、神经毒性和发育毒性。它被认为是一种潜在的持久性有机污染物,不仅在环境介质中普遍存在,而且在动物体、甚至人体中均被检出。目前关于TBBPA的电化学检测研究虽有报道,但几乎都采用间接的方法,通过检测其它物质的信号变化来实现。因此,开展灵敏、简便、快速、准确的TBBPA直接电化学检测新机制和新方法研究意义重大。目的：本论文拟借助纳米增敏和表面活性剂增敏,构建几种高灵敏的TBBPA直接电化学传感体系,并研究其增敏机制,考察其实际应用情况。方法：本文通过滴涂法、电化学沉积法等制备得到不同种类的敏感膜修饰电极,通过扫描电子显微镜,原子力显微镜表征了它们的表面形貌。采用循环伏安法,差分脉冲伏安法等方法考察了不同修饰电极对TBBPA的电化学响应情况。采用电化学阻抗法,计时库仑法等研究了不同的敏感膜对TBBPA信号增敏机理。优化了测定参数,确定了最优的测定条件。结果：主要包括以下六个部分：(1)用循环伏安法研究了TBBPA在不同pH值缓冲溶液中,在玻碳电极表面的电化学行为,探讨了pH值的影响规律,实验表明在pH=4.6时TBBPA的不可逆氧化信号最强。在此基础上,研究了TBBPA的氧化反应机理,其电化学氧化过程涉及一个电子和一个质子参与。用微分脉冲伏安法研究了低浓度TBBPA在玻碳电极表面的响应行为,结果表明TBBPA在裸玻碳表面的氧化活性很低,不能胜任痕量检测。(2)将不溶的乙炔黑颗粒超声分散在三种不同的体系中,如N,N-二甲基甲酰胺(DMF)、壳聚糖(CS)醋酸溶液以及双十六烷基磷酸(DHP)/水体系；通过挥发溶剂法得到不同乙炔黑敏感膜。扫描电镜、原子力显微镜、粒度分析和电化学探针实验表明分散介质对乙炔黑的分散能力、薄膜的形貌和电化学反应活性均有显著的影响。研究了TBBPA的电化学行为,在所制备的不同乙炔黑薄膜表面,TBBPA的氧化信号得到不同程度的增强；并进一步探讨了不同分散体系制备的乙炔黑薄膜对TBBPA氧化信号的增强机制,建立了一种TBBPA的直接电化学检测新方法,线性范围为10～350μgL-1,检出限为6.08μg L-1 (11 nM)。将其用于水样分析,加标回收率在99.3%～104.5%之间。(3)研究了TBBPA在阳离子、阴离子以及中性表面活性剂存在下的电化学行为,发现TBBPA的氧化信号在阴离子表面活性存在时明显降低,在中性表面活性剂存在下略有增加,而在阳离子表面活性剂存在时显著增强。进一步考察阳离子表面活性剂十六烷基三甲基溴化铵(CTAB)的浓度对TBBPA的氧化信号的影响规律,探讨了其增敏机制,发现在CTAB存在时,TBBPA在碳糊电极表面的富集效率和电子转移能力得到显著提升。基于此,建立了一种直接电化学测定TBBPA的新方法,线性范围为2.5～800 nM,检出限为0.99nM：将此方法用于水样分析,结果准确,加标回收率在94.59%～102.75%之间。(4)分别以含一条、两条和三条十八烷基链的疏水性阳离子表面活性剂在玻碳电极表面构建出三种TBBPA敏感膜,研究了TBBPA在不同表面活性剂薄膜表面的电化学行为,发现TBBPA的电子交换速率和富集效率均得到不同程度的提升；表面活性剂所含疏水链的数目影响敏感膜对TBBPA的信号增强能力,其中以双十八烷基二甲基溴化铵的增敏效应最为显著。优化了测定条件,构建了一种TBBPA的电化学检测平台,线性范围为1.0～500μgL-1,检出限为0.57 μg L-1 (1.05 nM)。将其用于电子垃圾样品分析,测定结果与高效液相一致。(5)通过溶剂剥离制备出高品质石墨烯纳米片(GS),借助挥发溶剂法得到GS修饰玻碳电极,然后在其表面继续修饰双十八烷基二甲基溴化铵(DODMA),构建了一种GS-DODMA复合薄膜传感平台。在单纯的GS及DODMA表面,TBBPA的氧化信号得到明显的提升,而在GS-DODMA复合膜表面,TBBPA的氧化信号进一步得到显著的增强。研究了GS和DODMA的协同增敏机制,结果表明富集效率的显著提高是主要原因。基于GS-DODMA复合膜的协同信号增强,建立了一种高灵敏的TBBPA电化学检测新方法,线性范围为0.1～400μgL-1,检出限为41.8 ng L-1(76.8 pM)。将其用于水样检测,加标回收率在97.5%～105.9%之间。(6)分别在-0.60,-0.50,-0.40,-0.30和-0.20 V下,通过恒电位还原在玻碳电极表面原位沉积金纳米颗粒(AuNPs)。原子力显微镜表征及电化学阻抗研究表明还原电位不仅影响AuNPs的表面形貌,而且还能有效地调控AuNPs的有效响应面积和电子转移速率等电化学活性。研究了TBBPA的氧化行为,发现不同电位下制备的AuNPs对TBBPA的氧化表现出不同的增敏效应,形貌影响显著：此外,还发现溶液中加入2-巯基苯并噻唑后,TBBPA在AuNPs表面的氧化信号进一步明显增加,表现出强的协同效应。在此基础上,研究了AuNPs和2-巯基苯并噻唑的协同增敏机制,并考察了沉积电位、pH值、2-巯基苯并噻唑浓度以及富集时间的影响,构建了一种新型的TBBPA电化学传感平台,测定的线性范围为0.5到30μgL-1,检出限为0.12μg L-1 (0.22 nM)。将其用于实际水样检测,加标回收率在97.2%～103.6%之间。此传感体系不仅灵敏度高、准确性好,而且敏感膜的制备通过电化学过程来实现,在现场自动化监测方面有很好的应用前景。结论：本论文深入研究了乙炔黑、石墨烯、纳米金等纳米材料以及不同结构表面活性剂对TBBPA的电化学增敏效应,阐述了增敏机制,建立了5种高灵敏度、快速简便的TBBPA电化学检测新方法,并用于实际样品分析,准确度高、实用性好。
[Abstract]:Tetrabromobisphenol A (TBBPA) is a widely used brominated flame retardant with endocrine disruption, immunotoxicity, neurotoxicity and developmental toxicity. It is considered to be a potential persistent organic pollutant. It is not only ubiquitous in environmental media, but also found in animals and even human beings. Although there are reports on chemical detection, almost all of them use indirect methods to detect the signal changes of other substances. Therefore, it is of great significance to develop sensitive, simple, rapid and accurate new mechanisms and methods for direct electrochemical detection of TBBPA. The sensitive TBBPA direct electrochemical sensing system was studied, and its sensitization mechanism was studied, and its practical application was investigated. METHODS: Different kinds of sensitive film modified electrodes were prepared by trickling method and electrochemical deposition method, and their surface morphology was characterized by scanning electron microscopy and atomic force microscopy. The electrochemical response of different modified electrodes to TBBPA was investigated by pulse voltammetry. The mechanism of TBBPA signal sensitization was studied by electrochemical impedance spectroscopy and chronocoulometry. The electrochemical behavior of TBBPA on the surface of glassy carbon electrode in different pH buffer solution was studied. The effect of pH value on the electrochemical behavior of TBBPA was investigated. The results showed that the irreversible oxidation signal of TBBPA was the strongest at pH=4.6. On this basis, the oxidation mechanism of TBBPA was studied. The electrochemical oxidation process involved an electron and a proton. The response behavior of low concentration TBBPA on glassy carbon electrode surface was studied by partial pulse voltammetry. The results showed that TBBPA on bare glassy carbon surface had low oxidation activity and could not be used for trace detection. Hexadecyl phosphoric acid (DHP) / water system; different acetylene black sensitive membranes were prepared by volatile solvent method. Scanning electron microscopy, atomic force microscopy, particle size analysis and electrochemical probe experiments showed that the dispersion ability of acetylene black, morphology and electrochemical reactivity of the films were significantly affected by the dispersing medium. The oxidation signal of TBBPA was enhanced to different extent on the surface of different acetylene black films, and the enhancement mechanism of TBBPA oxidation signal on the surface of different dispersion systems was further discussed. A new direct electrochemical detection method for TBBPA was established. The linear range of TBBPA was 10-350 ugL-1 and the detection limit was 6.08 ugL-1 (11 n). (3) The electrochemical behavior of TBBPA in the presence of cations, anions and neutral surfactants was studied. It was found that the oxidation signal of TBBPA decreased significantly in the presence of anionic surfactants, increased slightly in the presence of neutral surfactants, and increased slightly in the presence of cationic surfactants. The concentration of cationic surfactant cetyltrimethylammonium bromide (CTAB) on the oxidation signal of TBBPA was further investigated, and the sensitization mechanism was discussed. It was found that the enrichment efficiency and electron transfer ability of TBBPA on the surface of carbon paste electrode were significantly improved in the presence of CTAB. A new direct electrochemical method for the determination of TBBPA was developed. The linear range was 2.5-800 nM and the detection limit was 0.99 nM. The method was applied to the analysis of water samples. The results were accurate and the recovery was 94.59%-102.75%. (4) Hydrophobic cationic surfactants containing one, two and three octadecyl chains were constructed on the surface of glassy carbon electrode, respectively. Three TBBPA sensitive membranes were constructed to study the electrochemical behavior of TBBPA on the surface of different surfactant films. It was found that the electron exchange rate and enrichment efficiency of TBBPA were improved to varying degrees. The number of hydrophobic chains in the surfactant affected the signal enhancement ability of TBBPA sensitive membranes, among which, dioctadecyl dimethyl bromide was used as the bromide. An electrochemical detection platform for TBBPA was constructed with a linear range of 1.0-500 ugL-1 and a detection limit of 0.57 ugL-1 (1.05 nM). The results were in good agreement with those obtained by high performance liquid chromatography (HPLC). (5) High quality graphene nanotablets (GS) were prepared by solvent stripping. GS modified glassy carbon electrode was prepared by volatile solvent method, and then the surface of GS modified DODMA was modified to construct a GS-DODMA composite membrane sensing platform. On the surface of GS and DODMA, the oxidation signal of TBBPA was obviously enhanced, while on the surface of GS-DODMA composite membrane, the oxidation signal of TBBPA was further enhanced. The synergistic enhancement mechanism of GS and DODMA was studied. The results showed that the main reason was the significant enhancement of enrichment efficiency. Based on the synergistic signal enhancement of GS-DODMA composite membrane, a new highly sensitive TBBPA electrochemical detection method was established. The linear range was 0.1-400 ugL-1 and the detection limit was 41.8 ng L-1 (76.8 pM). The method was applied to water. The recovery of AuNPs was 97.5%-105.9%. (6) AuNPs were deposited on the surface of glassy carbon electrode by potentiostatic reduction at - 0.60, - 0.50, - 0.40, - 0.30 and - 0.20 V, respectively. Atomic force microscopy (AFM) and electrochemical impedance spectroscopy (EIS) showed that the reduction potential not only affected the surface morphology of AuNPs, but also effectively adjusted it. The oxidation behavior of TBBPA was studied. It was found that the surface of TBBPA exhibited different sensitization effects on the oxidation of TBBPA at different potential, and the morphology of TBBPA was significantly affected. In addition, it was found that the oxidation signal of TBBPA on the surface of AuNPs increased to one after adding 2-Mercaptobenzothiazole to the solution. On this basis, the synergistic sensitization mechanism of AuNPs and 2-Mercaptobenzothiazole was studied, and the effects of deposition potential, pH value, concentration of 2-Mercaptobenzothiazole and enrichment time were investigated. A novel TBBPA electrochemical sensing platform was constructed. The linear range of determination was 0.5 to 30 ugL-1. The detection limit is 0.12 UG L-1 (0.22 nM). The recoveries are 97.2%-103.6%. The sensor system is not only sensitive and accurate, but also the preparation of sensitive membrane is realized by electrochemical process. It has a good application prospect in field automatic monitoring. The electrochemical sensitization effect of nano-materials such as black, graphene, nano-gold and surfactants with different structures on TBBPA was studied. The sensitization mechanism was expounded. Five new methods of high sensitivity, fast and simple TBBPA electrochemical detection were established and applied to the analysis of real samples with high accuracy and good practicability.
【学位授予单位】：华中科技大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：R114

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