功能微针电极的构建及在海岸带水体典型金属元素检测中的应用研究
韩海涛
学位类型博士
导师潘大为
2020-05-13
学位授予单位中国科学院大学
学位授予地点中国科学院烟台海岸带研究所
学位名称工学博士
学位专业环境科学
关键词微针电极电化学检测海岸带水体金属元素形态分析
摘要海岸带是海洋与陆地相互作用的地带，是具有陆/海双重属性的复杂且动态的自然生态系统，也是陆/海域经济的核心和海洋开发活动的基地。入海河流、海湾、近岸海水、潟湖等，作为海岸带水体的主要类型，是海岸带生态系统的重要组成部分。金属元素在海岸带水体及海岸带生态系统中发挥着重要作用，与该区域的生态安全及人类健康密切相关。对海岸带水体中的金属元素进行快速检测，研究其形态与浓度分布，对保障海岸带生态系统安全及人类健康具有非常重要的意义。在金属元素的检测方法中，电化学分析法除了具有操作简便、灵敏度高、分析速度快等优势外，还能够对金属元素进行形态分析。传统汞电极在海水金属元素检测中，表现出了较高的灵敏度和稳定性。而微针电极作为一种新型工作电极，具有制备简单、使用方便、绿色无毒等特点，可以克服汞电极在制备、存储、运输、现场应用等方面的不便，展现出了广阔的应用前景。但是，关于微针电极对金属离子的检测，尤其是在实际水体环境中的应用，鲜有报道。而且，由于灵敏度的限制，未经功能修饰的微针电极并不能直接用于海岸带水体中金属元素的检测。因此，构建新型功能修饰微针电极，并用于海岸带水体中金属元素的检测，将有力推动电化学传感器在海岸带环境分析中的应用。本论文在新型功能微针电极的构建、不同金属元素检测方法的建立、以及海岸带水体（河水、近岸海水）中不同金属元素的形态分析应用上进行了一系列研究。主要研究内容包括以下方面：1. 树枝状纳米金/阳离子交换膜功能化微针电极用于海水中Cu的形态分析为实现海岸带水体中Cu的形态分析，本章以商品化不锈钢针灸针为基体，通过绝缘、密封等过程制备了微针电极（MNE），并采用树枝状纳米金（AuNDs）及阳离子交换膜（Nafion）对其进行功能修饰，构建了一种新型功能微针电极。AuNDs可以增强电极的导电性及电化学催化活性，Nafion除作为保护层提高电极的稳定性外，还由于其富集能力可以提高电极的检测性能。所制备的MNE针尖传感面长度大约为1~2 mm，AuNDs的尖端宽度和长度分别为40~60 nm和250~400 nm。该功能微针电极用于Cu2+的溶出伏安检测机理符合“吸附—催化”模型，在最佳条件下对Cu2+的线性响应范围为0.05~1 nM，检出限为0.02 nM。基于所构建的功能微针电极，结合不同的样品前处理过程，采用电化学阳极溶出伏安法成功对近岸海水中的不同形态Cu（活性态、溶解酸提取态、总酸提取态）进行了检测，实现了海水中Cu的形态分析。2. 多孔金/聚多巴胺功能化微针电极用于海水中Cu的检测上一章节中所制备的微针电极MNE表面非常光滑，不利于Au纳米材料的修饰及固定。为此，本章提出了一种全自组装构建功能微针电极的方法：利用多巴胺的自聚合性质，在MNE表面自组装一层聚多巴胺（PDA）进行表面改性，并利用PDA的还原性，在电极表面自组装一层多孔金（P-Au）纳米材料，构建功能微针电极。自组装得到的PDA为球形，在还原氯金酸形成Au纳米材料的同时，本身被部分氧化消耗，致使覆盖其上的Au纳米材料呈现多孔状。表面改性材料PDA除了可以为Au纳米提供更多的活性结合位点外，其还具有粘附性能，可以起到固定剂的作用，防止Au纳米材料脱落。在无阳离子交换膜Nafion作保护层的情况下，该功能微针电极用于Cu2+检测的线性范围为0.7~100 nM，检测限为0.24 nM，并且在近岸海水中Cu的检测上展现出了较好的灵敏度及稳定性。3. 金纳米簇/导电聚合物膜功能化微针电极用于海岸带水体中Fe的检测Fe作为一种金属营养元素，在海岸带生态系统及海洋生物地球化学循环中起着非常重要的作用。本章在以导电聚合物膜（PEDOT-PSS）对MNE进行表面改性的基础上，采用金纳米簇（AuNCs）进行功能修饰，构建了一种能够用于海岸带水体中Fe检测的新型功能微针电极。PEDOT-PSS作为一种性能优异的导电高分子聚合物膜，可以提高电极的导电性，增加活性位点以结合对Fe溶出伏安检测具有优异电化学催化性能的AuNCs。在最佳条件下，该功能微针电极用于Fe3+检测的线性范围为0.01~5 μM，检出限为3.1 nM。该功能微针电极成功用于了烟台入海河流（逛荡河）19个样品中Fe的检测。4. 三维还原氧化石墨烯/花状铋纳米片功能化微针电极用于海岸带水体中Pb的检测为实现海岸带水体中具有较大毒性及危害的重金属元素Pb的检测，本章通过分步电沉积法构建了一种基于三维还原氧化石墨烯（3DrGO）/花状铋纳米片（F-BiNSs）的功能微针电极。首先在MNE表面修饰一层3DrGO，提高电极的导电性，增大比表面积，并为Bi纳米材料提供更多的附着位点。然后在3DrGO表面电沉积F-BiNSs，利用Bi能够与待测金属元素Pb形成类似汞齐合金的性质，增强电极对Pb2+的电化学溶出伏安响应，提高电极的灵敏度。该功能微针电极对Pb2+具有良好的电化学响应，最佳检测条件下的线性范围为40~600 nM，检出限为12.5 nM。此功能微针电极最终成功实现了对海岸带水体中Pb的检测。5. 金-汞功能化微针电极用于海岸带水体中不同金属元素的同时检测为探究功能微针电极用于海岸带水体中不同金属元素同时检测的可行性，本章在制备MNE后，通过分步电沉积法构建了Au-Hg功能化微针电极，并与传统Hg电极在金属元素同时检测方面进行了比较。结果表明：采用Hg电极可以对海水中的Cu、Pb、Cd、Zn四种金属元素进行同时测定；采用Au-Hg功能化微针电极可以对Cu、Pb、Cd进行同时检测，并能实现海岸带水体中总溶解态Cu、Pb的同时测定，以及活性Cu的直接检测。后期进一步对微针材质、功能修饰材料、检测条件等进行优化，有望实现功能微针电极对海岸带水体中活性态和总溶解态Cu、Pb、Cd的同时检测。
其他摘要Coastal zone, the field of interaction between ocean and land, is a complex and dynamic natural ecosystem with dual attributes of land and sea. It is also the core of land and oceanic economy and the base of marine exploitation activities. Coastal waters mainly include coastal rivers, bays, coastal seawater, lagoons, and so on, which are important part of coastal ecosystem. Metals play an important role in coastal waters and ecosystem, which are closely related to the ecological safety of coastal zone and human health. It is very important to detect the metals rapidly and study their species and concentration distribution in coastal waters for the protection of coastal ecosystem and human health.Among the methods for determination of metals, in addition to the advantages of simple operation, high sensitivity and fast analysis speed, electrochemical methods can also be used for the speciation analysis of metal elements. Mercury electrode shows high sensitivity and stability for the detection of metals. As a new working electrode, micro-needle electrode has the properties of easy fabrication, easy to use, non-toxicity, and so on. It can overcome the inconvenience of mercury electrode in preparation, storage, transportation, and on site application, which shows a broad application prospect. However, there are few reports about the determination of metal ions by micro-needle electrode, especially in the actual water environment. Furthermore, the unfunctionalized micro-needle electrode cannot be used for determination of metals directly in coastal waters due to its relatively low sensitivity. Therefore, the fabrication of new functional micro-needle electrodes for determination of metal ions in coastal waters will greatly promote the application of electrochemical sensors in the coastal environment analysis. In this thesis, a series of researches have been carried out, including the fabrication of functional micro-needle electrodes, the development of detection methods for different metals, and the speciation analysis of metals in coastal waters including coastal river water and coastal seawater. The main contents are as follows:1. Dendritic gold nanostructures/cation-exchange polymer functionalized micro-needle electrode for the speciation analysis of Cu in seawater In order to realize the speciation analysis of Cu in coastal waters, a new micro-needle electrode (MNE) was prepared through insulation, sealing, and other processes by using commercial stainless steel acupuncture needle as the matrix. The MNE was then functionalized with dendritic gold nanostructures (AuNDs) and cation-exchange polymer (Nafion) to prepare the functional MNE. AuNDs improved the conductivity and electrocatalytic activity of the electrode. Nafion could not only improve the stability of the electrode as a protective layer, but also improve the detection performance of the electrode through its enrichment ability. The sensing tip of the prepared MNE was about 1~2 mm, and the top width and length of the AuNDs were about 40~60 nm and 250~400, respectively. The detection mechanism of Cu2+ with the functional MNE accorded with the “adsorption-catalysis” model. Under the optimal conditions, the functional MNE showed a linear response range of 0.05~1 nM and detection limit of 0.02 nM for Cu2+. Different species of Cu (active state, dissolved acid extractable state and total acid extractable state) in coastal seawater samples were determined by combining different sample pretreatments and electrochemical anodic stripping voltammetry. Eventually, the speciation analysis of Cu in seawaters was realized with the so-prepared functional MNE. 2. Porous gold/polydopamine functionalized micro-needle electrode for determination of Cu in seawaterThe surface of MNE prepared in the previous chapter was very smooth, which was not beneficial to the modification and attachment of gold nanomaterials. Therefore, in this chapter, a method of self-assembly was proposed to prepare the functional MNE. A layer of polydopamine (PDA) was first self-assembled on the surface of MNE for the surface modification by using the self-polymerization property of dopamine. Then a layer of porous gold (P-Au) was self-assembled on the surface of electrode by using the reducibility of PDA to fabricate the functional MNE. The self-assembled spherical PDA was partially oxidized and consumed with the reduction of chloroauric acid to gold nanomaterials, which resulted in the porous structure of gold nanomaterials covered on the PDA. As the surface modification material, PDA could not only provide more active binding sites for gold nanomaterials, but also act as the adhesion agent to prevent their from falling off from the electrode due to its adhesion property. In the absence of Nafion as the protective layer, the linear range and the detection limit of the functional MNE for Cu2+ was 0.7~100 nM and 0.24 nM, respectively. Furthermore, the functional MNE showed a good sensitivity and stability for determination of Cu in coastal seawater.3. Gold nanoclusters/conducting polymer film functionalized micro-needle electrode for determination of Fe in coastal watersAs a metal nutrient element, Fe plays an important role in coastal ecosystem and marine biogeochemical cyle. In this work, a functional MNE was fabricated for determination of Fe in coastal waters. The MNE was firstly modified with the conducting polymer film (PEDOT-PSS) to achieve the surface modification, and then functionalized with gold nanoclusters (AuNCs). As a kind of conductive polymer film with excellent performance, PEDOT-PSS improved the conductivity of the electrode and increased the active sites for the combination of the AuNCs which had excellent catalytic performance for the voltammetric determination of Fe. Under the optimal conditions, the functional MNE showed a linear response range of 0.01~5 μM and detection limit of 3.1 nM for Fe3+. The functional MNE was successfully applied to the determination of Fe in 19 samples from the coastal river of Yantai (Guangdang River).4. 3D reduced graphene oxide/flower-like bismuth nanosheets functionalized micro-needle electrode for determination of Pb in coastal watersIn order to realize the determination of Pb which is one of the heavy metal elements with relatively high toxicity and harm in coastal waters, a functional MNE based on 3D reduced graphene oxide (3DrGO)/flower-like bismuth nanosheets (F-BiNSs) was fabricated through stepwise electrodeposition method. A layer of 3DrGO was first modified on the surface of MNE to improve the conductivity and specific surface area of the electrode and provide more binding sites for bismuth nanomaterials. Considering the properties of bismuth in easy formation of alloy like amalgam with Pb2+ which was the metal ion to be tested, the F-BiNSs was electrodeposited on the surface of 3DrGO to enhance the voltammetric response to Pb2+ and improve the sensitivity of the electrode. The functional MNE showed a good electrochemical response to Pb2+ with the linear range of 40~600 nM and detection limit of 12.5 nM. The determination of Pb in coastal waters was successfully realized by this functional MNE.5. Gold-mercury functionalized micro-needle electrode for the simultaneous determination of different metals in coastal watersThe main aim of this chapter is to investigate the practicability of the functional MNE for simultaneous determination of different metals in coastal waters. So, after the preparation of MNE, a gold-mercury (Au-Hg) functionalized MNE was constructed through stepwise electrodeposition method, and compared with the traditional mercury electrode in the simultaneous detection of metals. The results showed that the simultaneous detection of four metals of Cu, Pb, Cd and Zn in seawater can be realized by the mercury electrode. The so-fabricated functional MNE could be used for the detection of Cu, Pb, and Cd at the same time and simultaneous determination of total dissolved Cu and Pb, as well as the direct detection of active Cu in coastal waters. In the later stage, the micro-needle materials, functional materials and detection conditions will be further optimized, which is expected to achieve the simultaneous detection and analysis of active and total dissolved Cu, Pb, and Cd in coastal waters by the functional MNE.
页数116
语种中文
文献类型学位论文
条目标识符http://ir.yic.ac.cnhttp://ir.yic.ac.cn/handle/133337/25303
专题中科院烟台海岸带研究所知识产出_学位论文

推荐引用方式
GB/T 7714韩海涛. 功能微针电极的构建及在海岸带水体典型金属元素检测中的应用研究[D]. 中国科学院烟台海岸带研究所. 中国科学院大学,2020.


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