【作者】 许贺；

【导师】 金利通；

【作者基本信息】 华东师范大学 ， 分析化学， 2009， 博士

【摘要】 食品安全问题一直是人类关注的焦点。随着工农业生产的迅速发展，食品污染问题越来越严重，其中重金属是最主要的污染物质之一。重金属可以在土壤中积累和作物体内残留，通过食物链而进入人体内蓄积，构成对人体的潜在危害。人体内重金属含量过量时，会导致各种疾病的发生。食品重金属污染问题已引起全世界的高度重视和深入研究，对不同种类食品和水体中的重金属污染进行监测和分析研究，对于评价食品质量、保护人类健康和维持社会经济可持续发展具有重要的现实意义。该课题得到了上海市世博会重点项目专项基金的资助。纳米材料是指在三维空间中至少有一维处于1～100nm纳米尺度范围或由它们作为基本单元构成的材料。纳米复合材料是近年来发展较为迅速的一种新兴纳米材料，它是由两种或两种以上的吉布斯固相至少在一维以纳米级大小复合而成的纳米材料。在纳米复合材料中，纳米尺度的分散相不仅大大增加了两相界面面积，而且由于其纳米尺度效应将大大增强界面相互作用。它与单一纳米材料和纳米相材料不同，不仅具有纳米尺度物质单元的基本特性：量子尺寸效应、表面效应、小尺寸效应、量子隧道效应、介电限域效应等，又存在纳米结构组合所引起的新效应：量子耦合效应和协同增强效应等，使得纳米复合材料的综合性能优于原组成材料而能够满足各种不同的实际应用要求，被誉为是21世纪最有前途的材料之一。随着纳米技术的发展，纳米复合材料作为一种新型的电极材料在电化学检测和分析方面受到人们的日益关注。微波辐射作为一种快速、简单和高效的加热技术，已经广泛地被运用于化学反应和多种纳米材料的合成。与传统的加热方法比较，微波加热具有快速和均匀的优点，从而可以大大加快反应速度，得到更小和更均匀的纳米粒子。微波—电化学是将微波技术与电化学原理相结合形成的一种新型科学技术，将微波技术引入电化学检测还是一个较新的领域，尤其是微波一电化学联用技术应用于重金属的检测是一种全新的理念和思路。虽然微波技术在电化学检测领域已经得到初步的应用，但这一领域的研究目前还处于起步阶段。特别是微波条件下快速合成纳米材料，并将合成的纳米材料应用于微波—电化学检测重金属离子的研究还未见报道。本论文通过电化学方法、微波辐射合成方法制备纳米复合材料，并将其作为电极材料应用于食品中痕量重金属，如Pb、Cd、Hg、As、Cr的电化学检测与分析。通过扫描电子显微镜、透射电子显微镜、原子力显微镜、能量散射X-射线光谱对合成的纳米复合材料形貌和组成进行表征，运用阳极溶出伏安法、线性扫描伏安法、安培检测法、微波—电化学协同体系对痕量重金属进行检测与分析，并在此基础上研制与开发重金属快速分析仪。本论文共分为九章：第一章绪论本章内容主要包括重金属污染及危害、重金属检测技术的研究与发展、纳米复合材料及其应用于重金属检测的研究与进展、重金属快速分析仪研究现状四部分。文中简要介绍了食品中重金属污染现状、光谱方法应用于重金属检测的研究，着重综述了电分析方法应用于重金属的检测和发展；对纳米复合材料的分类、性能和制备进行了概述，着重阐述了微波合成纳米复合材料及其应用于食品中重金属检测的研究与发展，并介绍了重金属快速分析仪的研究现状和应用前景。第二章Nafion修饰铋膜电极应用于蔬菜中痕量重金属的检测研究本章以Nafion修饰铋膜电极（NCBFE）为工作电极，采用微分脉冲阳极溶出伏安法直接检测蔬菜中痕量铅、镉和锌的研究。考察铋膜浓度、Nafion厚度、沉积时间和表面活性大分子对检测结果的影响。实验结果表明，Nafion修饰铋膜电极对痕量铅、镉和锌具有良好的电化学响应，铋和待测元素形成“二元”合金，极大地提高了富集效率，且Nafion膜的存在，大大提高了检测方法的灵敏度和工作电极的抗干扰能力，方法的稳定性和重现性增强。该方法成功应用于蔬菜中痕量重金属的测定，检测结果与石墨炉原子吸收法有良好的相关性，具有极大的应用前景。第三章MWCNTs／Bi／Nafion复合材料电极应用于饮用水中痕量Pb（Ⅱ）和Cd（Ⅱ）的检测研究本章采用电化学沉积的方法制备多壁碳纳米管／铋膜／Nafion（MWCNTs／Bi／Nafion）复合材料，并将其作为工作电极应用于检测饮用水中痕量Pb（Ⅱ）和Cd（Ⅱ）的研究。运用阳极溶出伏安法考察MWCNTs／Bi／Nafion复合材料电极对Pb（Ⅱ）和Cd（Ⅱ）的电化学响应，并考察MWCNTs／Nafion悬浮液体积、铋膜浓度对检测结果的影响。研究结果表明，MWCNTs／Bi／Nafion复合材料电极对水体中的痕量Pb（Ⅱ）和Cd（Ⅱ）具有优异的电化学信号，灵敏度和稳定性均优于MWCNTs／Nafion和Bi／Nafion复合电极。采用该复合材料电极应用于饮用水中痕量Pb（Ⅱ）和Cd（Ⅱ）的检测，实测样品值与石墨炉原子吸收法结果相符，回收率为95-107％，证明该方法具有良好的准确性和可靠性，具有实际应用意义。第四章微波辐射合成Au-NPs／CNTs复合材料的制备、性能表征及其应用于水体中痕量Hg（Ⅱ）的检测研究本章利用微波辐射快速合成金纳米粒子／碳纳米管（Au-NPs／CNTs）复合材料，并首次将其应用于溶出伏安法检测水体中痕量Hg（Ⅱ）。通过透射电子显微（TEM）、能量散射X-射线光谱（EDX）、紫外可见吸收光谱（UV-vis）和循环伏安法对合成的Au-NPs／CNTs复合材料的形貌和组成进行表征。采用溶出伏安法，Au-NPs／CNTs修饰玻碳电极（Au-NPs／CNTs／GCE）对痕量Hg（Ⅱ）的检测显示出优良的电化学性能，具有线性范围宽，灵敏度高，稳定性好，可重复使用等优点，该方法可以成功应用于实际样品中痕量Hg（Ⅱ）的检测与分析，具有实际应用价值。第五章微波辐射合成Ptnano／CNTs复合材料及其应用于氧化检测水体中痕量As（Ⅲ）的研究本章以微波辐射快速合成Pt纳米粒子／碳纳米管（Ptnano／CNTs）复合材料，并且首次将其应用于氧化检测痕量砷（Ⅲ）的研究。运用透射电子显微镜（TEM）对Pt_nANO／CNTs复合材料的形貌进行表征，负载在CNTs表面的Pt纳米粒子直径为15±3nm。采用循环伏安法和线性扫描伏安法对Ptnano／CNTs纳米复合材料的电化学性能进行考察，结果显示，与电化学沉积法制备的Pt纳米粒子修饰玻碳电极(Pt_nano／GCE)、Pt盘电极相比，Pt_nano／CNTs修饰的玻碳电极（Ptnano／CNTs／GCE）显示出更优越的检测砷（Ⅲ）的性能，具有良好的重现性和稳定性，且本方法的检测限为比Ptnano／GCE和Pt盘电极低1-2个数量级，同时避免了Cu（Ⅱ）离子和氯离子的干扰，该方法快速、准确，适合于痕量砷（Ⅲ）的常规检测。第六章高度有序铂纳米管阵列电极应用于氧化检测痕量砷（Ⅲ）的研究本章报道一种新颖的方法，即高度有序铂纳米管（PtNTs）阵列电极应用于氧化检测痕量砷As（Ⅲ）的研究。运用3-氨丙基三甲氧基硅烷（APS）修饰的多孔氧化铝模板（PAA）在含有AuCl₄^-溶液中，采用电化学沉积的方法得到高度有序PtNTs阵列结构。利用扫描电子显微镜（SEM）和X-射线衍射（XRD）对PtNTs阵列的形貌和结构进行表征。通过电化学研究表明，PtNTs阵列结构具有更大的有效面积和更高的催化性能。与Pt纳米粒子修饰玻碳电极（Pt-NPs／GC）和Pt盘电极相比，痕量砷（Ⅲ）在PtNTs阵列电极上具有更优良的电化学信号，具有线性范围宽，灵敏度高，选择性好等优点，且检测限比文献报道的Pt-NPs／GC和Pt盘电极低1-2个数量级，证明该方法具有更优异的电化学性能，对于痕量As（Ⅲ）的常规检测具有潜在的应用价值。第七章微波—伏安法协同体系应用于水体中痕量Cu（Ⅱ）和Pb（Ⅱ）的检测研究本章研究微波-伏安法协同体系对金纳米粒子修饰的铂微电极（Au-NPs／Pt）与裸Pt微电极分别检测Cu（Ⅱ）和Pb（Ⅱ）电化学性质的影响，研究微波辐射的“自聚焦”作用在电极／电解质扩散层形成的“热点效应”、温度梯度和对流传质。采用单电子转移的Fe（CN）6^3-／4-／K₂SO₄（pH 3）标准溶液对电极／电解质界面温度进行校正。研究结果发现，低功率微波对Cu（Ⅱ）和Pb（Ⅱ）离子在Au-NPs／Pt和Pt微电极上的电化学性质影响较为明显；微波-伏安法协同作用下，采用循环伏安法检测Cu（Ⅱ）和示差脉冲阳极溶出伏安法检测Pb（Ⅱ），它们的电流响应极大增强，比传统方法增加近10倍；常规条件下易于阻塞电极的表面活性剂在微波-伏安协同体系中对Cu（Ⅱ）和Pb（Ⅱ）峰电流的影响大大减小。本文提出的微波-伏安协同体系有望应用于重金属和其他有毒污染物检测装置的研制与开发。第八章AuNPs／PtNF纳米复合电极的制备、性能表征及其应用于检测废水中痕量Cr（Ⅵ）的研究本章以简单快速和环保的方式制备金纳米粒子修饰铂纳米多孔膜（AuNPs／PtNF）复合电极。Pt盘电极在高压6V电压下阳极氧化后，经抗坏血酸还原后得到铂纳米多孔膜（PtNF）电极；采用循环伏安法在PtNF电极表面电沉积Au纳米粒子制备AuNPs／PtNF复合电极。运用扫描电子显微镜（SEM）和能量散射X-射线光谱（EDX）对AuNPs／PtNF纳米复合电极的形貌和组成进行表征。通过循环伏安法（CV）考察AuNPs／PtNF纳米复合电极的电化学性质。研究结果表明，利用该电化学方法制备的AuNPs／PtNF纳米复合电极具有更大的电活性面积和更优异的电催化性能。AuNPs／PtNF纳米复合电极成功应用于安培检测痕量Cr（Ⅵ）的研究，与Pt盘电极和PtNF电极相比，该复合电极对Cr（Ⅵ）具有更好的电化学响应，更易于Cr（Ⅵ）的还原检测。采用此方法制备的AuNPs／PtNF纳米复合电极简单方便、反应时间短、样品消耗量少，是一种新颖的制备复合材料的方法。第九章重金属快速分析仪的研制与开发本章根据电化学原理，结合纳米复合材料的特殊性能，研制开发了一种以电化学分析为检测手段的重金属快速分析仪。本仪器对重金属的检测具有快速、灵敏、准确和无污染等特点，而且可以同时测定多种重金属元素，与光谱检测方法具有较好的一致性。该仪器小型化设计，携带方便，性能稳定，质量可靠，是一种极有推广应用前景的分析仪器。更多还原

【Abstract】 The food security problem has been focused on for a long time.With thedevelopment of industrial and agricultural manufacture,food contamination isincreasing serious,especially for heavy metals contamination.The residence time ofmost heavy metals in soils and plants is very long.Taken by plants,heavy metals mayenter the food chain in significant amounts.Hence,people could be at risk of adversehealth effects from consuming food grown in soils containing elevated metalconcentrations.Considerable interest and extensive study have developed in thedetermination of heavy metals in food all over the world.Therefore,it is practicallyimportant for the detection of toxic heavy metals in different kinds of food and waterin evaluating food quality,protecting human health and promoting sustainabledevelopment of economy and society.Nanomaterials are defined as the materials with domain ranges between 1 and100 nm at least in one dimension,or materials that be composed of nanoscale units.Nanocomposite materials have recently been shown to represent a novel anddeveloped rapidly nanomaterials,which are formed by no less than two solid phaseswith nanoscale size at least in one dimension.The nanoscale dispersed phase ofcomposite materials not only remarkably increased interface areas of two phases,butalso significantly enhanced interactions between two interfaces caused by nanosizeeffects.Difference from singular nanomaterials and nanophase,nanocompositematerials not only have the nanoscale units’ basic properties:quantum size effect,surface effect,small size effect,quantum tunneling effect,dielectric confinementeffect and so on,also exist new effects caused by combination of nano-structuredmaterials such as quantum coupling effect and synergistic effect,making their generalperformances are better than the original single materials and be able to meetrequirements for a variety of practical application.Nanocomposites are known as themost promoting materials in the 21^st century.With the development ofnano-technology,nanocomposites as a new type of electrode materials are applied inelectrochemical detection and analysis by people’s growing concern. Microwave radiation as a fast,simple and efficient heating technique has beenwidely applied for chemical reactions and a variety of nanomaterials synthesis.Theadvantages of this method over the conventional heating methods are speediness anduniformity,which result in improving kinetics of the reaction and obtaining narrowerdistribution of particle size.Microwave-electrochemistry is a new technique thatcombining the principle of microwave technology with electrochemical theory.Microwave technology into electrochemical detection is still a relatively new conceptand area,especially for heavy metals detection in the microwave-electrochemicalsynergistic system.Although microwave-electrochemistry has been a preliminaryapplication,research in this area is still in its infancy.The rapid microwave synthesisof nanocomposite materials which were applied to detect heavy metals undermicrowave-electrochemical system has not been reported.In this thesis,nanocomposite materials were synthesized via electrochemicalmethods and microwave irradiation,and applied for the determination of trace heavymetals （mainly including Pb、Cd、Hg、As、Cr） in food and water by electrochemicalstripping analysis.The morphology and composition of synthesized nanomaterialswere characterized by the means of scanning electron microscopy （SEM）,transmission electron microscopy （TEM）,atomic force microscopy （AFM） andenergy dispersive X-ray spectra （EDX）.The determination and analysis of traceheavy metals were carried out by anodic stripping voltammetry （ASV）,linearscanning voltammetry （LSV）,amperometric detection and microwave-electrocheicalsynergistic system.Based on this,manufacture of heavy metals rapid analysisinstrument was constructed and developed.Totally,there are nine chapters in thispaper.Chapter 1 PrefaceThis chapter has four parts,that is,heavy metals pollution and hazards,technicaldevelopment for heavy metals determination,research and development fornanocomposite materials and its application to heavy metals determination,manufacture of heavy metals rapid analysis instrument.The sort,actuality of heavymetals contamination in food and the development of spectral analysis for heavy metals detection have been brief introduced,and electrochemical analysis for heavymetals determination has also been reviewed in detail.Then nanocompositematerials’classification,properties and preparation methods has been reviewed.Thenanocomposite materials synthesized by microwave irradiation and its application toheavy metals determination has been discussed particularly.Lastly,we introduce theresearch status quo of manufacture of heavy metals rapid analysis instrument andreview its application and prospect.Chapter 2 A Nafion-coated bismuth film electrode for the determination of heavymetals in vegetable by anodic stripping voltammetryIn this chapter,Nafion-coated bismuth film electrode （NCBFE） as a workingelectrode was applied to determine trace Pb（Ⅱ）、Cd（Ⅱ） and Zn（Ⅱ） by differential pulseanodic stripping voltammetry.The effects on experimental results of bismuthconcentration,Nafion thickness,preconcentration time and surface active compoundswere examized in detail.The results showed that NCBFE has excellentelectrochemical performance for the determination of Pb（Ⅱ）、Cd（Ⅱ） and Zn（Ⅱ）.Bismuth has ability to form alloys with some metals such as cadmium,lead and zinc,improving the efficiency of deposition,and the sensitivity and tolerance to surfaceactive compounds were greatly enhanced by Nafion membrane,resulting inimproving remarkably the stability and reproducibility of the methods.The NCBFEwas successfully applied to determine trace heavy metals in vegetable samples,andthe results were in agreement with those of graphite furnace atomic absorptionspectrometry with the actual application value.Chapter 3 MWCNTs/Bi/Nafion composite materials electrodes for the detectionof trace Pb（Ⅱ） and Cd（Ⅱ） in drinking waterIn this chapter,multi-wall carbon nanotubes/bismuth film/Nafion membrane（MWCNTs/Bi/Nafion） composite materials were prepared by electrochemicaldeposition,and its application to detect trace Pb（Ⅱ） and Cd（Ⅱ） in drinking water.Thesynergistic effects on the electrochemical response for Pb（Ⅱ） and Cd（Ⅱ） determinationat the MWCNTs/Bi/Nafion composite electrodes were evaluated.The study resultsshowed the MWCNTs/Bi/Nafion composite electrodes have excellent signals for trace Pb（Ⅱ） and Cd（Ⅱ） determination,and both the sensitivity and stability were better thanthose of MWCNTs/Nafion and MWCNTs/Bi electrodes.The MWCNTs/Bi/Nafioncomposite electrodes were successfully applied to determine Pb（Ⅱ） and Cd（Ⅱ） in realsample,and the results of the present method agreed well with those of atomicabsorption spectroscopy.The recovery is 95-107%,proving that the proposed methodhas good accuracy and reliability with the practical application of significance.Chapter 4 The preparation and characterization of Au-NPs/CNTs compositematerials by microwave radiation and its application to detect trace Hg（Ⅱ）Gold nanoparticles/carbon nanotubes （Au-NPs/CNTs） composites were rapidlysynthesized by microwave radiation,and firstly applied for the determination of tracemercury（Ⅱ） by anodic stripping voltammetry （ASV）.The structure and compositionof the synthesized Au-NPs/CNTs nanocomposites were characterized by transmissionelectron microscopy （TEM）,energy dispersive X-ray spectroscopy （EDX）,UV-visabsorption spectroscopy and cyclic voltammetry.Au-NPs/CNTs nanocompositesmodified glassy carbon electrode （Au-NPs/CNTs/GCE） exhibited excellentperformance for Hg（Ⅱ） analysis with wide linear range,high sensitivity,good stability,and repetitive useness.The Au-NPs/CNTs composite electrode was successfullyapplied to determine trace Hg（Ⅱ） analysis in water samples,suggesting the proposedmethod may have practical utility.Chapter 5 Microwave-irradiated synthesized platinum nanoparticles/carbonnanotubes for oxidative determination of trace arsenic（Ⅲ） in waterPlatinum nanoparticles/carbon nanotubes (Pt_nano/CNTs) were rapidlysynthesized by microwave radiation,and applied for the oxidative determination ofAs（Ⅲ）.The transmission electron microscopy （TEM） revealed the size of synthesizedPt nanoparticles with nominal diameter of 15±3 nm.The electrochemical propertiesof Pt_nano/CNTs composite electrode was investigated by cyclic voltammetry and linearscan voltammetry.The Pt_nano/CNTs modified glassy carbon electrode(Pt_nano/CNTs/GCE) exhibited better performance for As（Ⅲ） analysis than that of Ptnanoparticles modified GCE (Pt_nano/GCE) by electrochemical deposition or Pt foilelectrode with excellent reproducibility and stability.The limit of determination （LOD） of the Pt_nano/CNTs/GCE was 1-2 orders of magnitude lower than that of Pt_nano/GCE orPt foil electrode,and the proposed method avoided interferences from Cu（Ⅱ） andchloride ions existing commonly in water system,proving that the method wassuitable for routine determination of As（Ⅲ） with speediness and accuracy.Chapter 6 Highly ordered platinum-nanotube arrays for oxidative determinationof trace arsenic（Ⅲ）A novel method for the oxidative determination of trace arsenic（Ⅲ） wasinvestigated on highly ordered platinum-nanotube （PtNTs） array electrodes.ThePtNTs with a highly organized structure were fabricated by electrochemicaldeposition of platinum in a 3-aminopropyltrimethoxysilane-modified porous anodicalumina template （PAA） in solution containing AuCl₄^-.The morphologies andstructures of PtNTs arrays electrode were characterized by scanning electronmicroscopy （SEM） and X-ray diffraction （XRD）.Electrochemical experiments provedthat the PtNTs array electrode exhibited larger effective area and high catalyticproperties,which have better performance for As（Ⅲ） analysis in comparison withplatinum nanoparticles-coated GCE (Pt_nano/GCE) or Pt foil electrode.The PtNTs arrayelectrode showed to provide better reproducibility and higher sensitivity.The limit ofdetection （LOD） was typically 1-2 orders of magnitude lower than that of Pt_nano/GCEor Pt foil electrode,suggesting that the proposed method has potential applicationvalues for trace As（Ⅲ） analysis.Chapter 7 Microwave-voltammetry synergistic system for the determination ofCu（Ⅱ） and Pb（Ⅱ） in river waterIn this chapter,in situ microwave activation of electrochemical detection ofCu（Ⅱ） and Pb（Ⅱ） at a gold nanoparticles-modified Pt （Au-NPs/Pt） and bare Ptmicroelectrodes was investigated.Self-focusing of the microwave radiation creates anextreme localized heating at the electrode/solution （electrolyte） interface within thediffusion layer of the electrode with an inverted thermal gradient and convective flow.The temperature at the electrode/solution interface is calibrated with reversible oneelectron redox system Fe（CN）₆^3-/4- in aqueous K₂SO₄ solution （pH 3）.The resultsshowed that significantly increased currents of electron couple of Fe（CN）₆^3-/4- were observed at the Au-NPs/Pt and bare Pt microelectrodes under the low microwavepower.The Cu（Ⅱ） detection at the Au-NPs/Pt microelectrode by cyclic voltammetryand Pb（Ⅱ） detection by differential pulse stripping voltammetry were also shown to bestrongly enhanced by microwave radiation,which triggers Cu（Ⅱ） and Pb（Ⅱ） currentsresponse orders of magnitude higher than those expected values in conventionalconditions.The effect of surfactant,which blocks the electrochemical signals of Cu（Ⅱ）and Pb（Ⅱ） under conventional conditions,is remarkably decreased under the in situmicrowave radiation of electrochemical process.Results implied thatmicrowave-electrochemistry synergistic system is a promising approach to developinstruments for heavy metals or other pollutants determination.Chapter 8 The preparation and characterization of Au nanoparticles-coated Ptnanoporous film electrode and its application to detect Cr（Ⅵ） in waste waterThis chapter describes the preparation of Au-nanoparticles-coated Pt-nanoporousfilm （AuNPs/PtNF） on a platinum substrate via a simple,rapid and“green”approach.The platinum electrode that had been anodized under a high potential of 6 V isreduced by freshly prepared ascorbic acid （AA） solution to obtain platinumnanoporous film electrode.Then the Au nanoparticles were grown on the electrode bycyclic voltammetry （CV）.The morphology and composition of AuNPs/PtNFcomposite electrode were characterized by scanning electron microscopy （SEM） andenergy dispersive X-ray spectra （EDX）,and the electrochemical properties ofAuNPs/PtNF composites were examized by CV and amperometric analysis.Theresulting AuNPs/PtNF composite electrode has highly electroactive area and moreoutstanding properties.Furthermore,the as-prepared AuNPs/PtNF compositeelectrode exhibited high electrocatalytic activity toward Cr（Ⅵ） reductiondetermination compared to Pt foil electrode and PtNF electrode.The present novelstrategy for the preparation of AuNPs/PtNF composite electrode showed simpleness,short reaction time and low cost,suggesting that it is a promising approach forpreparation of nanocomposites materials.Chapter 9 Manfacture of heavy metals rapid analysis instrumentA rapid heavy metals analysis instrument was developed by means of electrochemical theory combined with the special properties of nanocompositematerials.This instrument has such advantages as speediness,sensitivity,accuracyand no contamination,even simultaneous determination of various metal elementswith satisfactory agreement with spectra analysis.The developed instrument hasminiaturized design,easy to take,stable performance and reliable quality,suggestingthat it is a very promising analytical instrument for application.更多还原