【作者】 李雅卓；

【导师】 王晓萍；

【作者基本信息】 浙江大学 ， 测试计量技术及仪器， 2013， 博士

【摘要】 水是人类的生命之源,是人类社会稳定发展的基本要素。因此对水体质量乃至功效的检测要求越来越高,研究开发先进可靠、快速灵敏、小型价廉的水质检测仪器是相关领域的热门课题。基于电化学伏安法的检测仪器,不仅灵敏度高、结构简单、性能稳定,而且具有较好的灵活性,可通过施加不同激励,更换不同材料的电极实现多种参数的检测,在水质检测分析中具有较好的优势。本课题在研究电化学三电极体系检测原理及常规伏安型检测仪器的基础上,设计了伏安型两电极体系检测系统。该系统采用比表面积大、电位稳定的固态电极为对电极,摒弃了传统三电极体系中需要内参比溶液的玻璃参比电极。运用该系统开展了水体pH、钙离子、氯离子、双氧水、铅离子以及咖啡溶液中咖啡因含量的检测研究。主要研究内容及成果包括以下几个方面：(1)在研究三电极体系的检测原理和仪器结构基础上,分析两电极体系的检测原理并提出两电极体系中对电极应具备的特性：电位稳定、化学惰性强、导电性好、机械强度高、免维护且成本低。先后设计研制了大面积不锈钢和活性炭两种对电极,并对它们的电极特性进行了深入研究。(2)开展两电极体系离子选择性检测研究。以全固态离子选择性电极和活性炭电极做为工作电极和对电极构成两电极体系检测系统。分别采用脉冲计时电流法和循环伏安法对水中pH值、钙离子和氯离子进行检测实验。实验结果表明,两种检测方法的响应与待测离子浓度的对数呈线性关系,r>0.997,RSD<1.05%。与传统电位分析方法相比,这两种方法不受工作电极中积累电荷的干扰,对于水体离子的实时在线监测具有较好的应用前景。(3)开发研制了一台使用方便、小型化的伏安型两电极体系检测仪器。该仪器由电极探头单元、MCU控制单元和软件处理单元组成。MCU控制单元具有切换工作电极、输出多种激励信号和实时采集电流响应信号的功能。软件处理单元具有工作方式选择、参数设置、与MCU通信、响应信号实时显示、数据分析处理以及根据算法模型获得检测结果等功能,实现了检测过程的自动化与智能化。(4)开展伏安型两电极体系检测仪器的应用研究,分别对双氧水、铅离子以及咖啡因小分子进行分析检测。对双氧水的检测采用脉冲计时电流法,响应电流与双氧水浓度呈线性关系,r=0.9970,RSD<2.10%。对铅离子的检测采用溶出伏安法,溶出峰电流与铅离子浓度呈线性关系,r=0.9996,检出限为1.69ppb。结果表明,该检测仪器的灵敏度、检测范围以及检测限均达到了传统三电极体系检测系统的结果。为扩展该仪器的应用领域,将其用于咖啡溶液中咖啡因小分子的检测。引入强碱型离子交换树脂对咖啡溶液进行预处理,去除干扰物质,增大咖啡因氧化峰响应,提高检测灵敏度。预处理后咖啡溶液中咖啡因的检测灵敏度为44μA/g,r=0.999。研究结果表明,以自制的伏安型两电极体系检测仪器为平台,通过选用不同的电极探头、结合多种检测方法,可实现水中pH值、矿物质离子与小分子的检测。该仪器具有检测精度高、性能稳定、电极结构简单、价格低、寿命长、易于维护及小型化、检测过程自动化与智能化等特点,在水质的实时在线监测中具有较好的应用前景。更多还原

【Abstract】 Water is the source of life, it is the basic element of stable development of human society. The detection of water quality and property are more demanding than ever before. As a result, developing an advanced, reliable, quick, sensitive and cheap small size water quality detecting instrument is a hot topic in the related fields.The detecting instrument based on voltammetric technique has a good advantage in water quality testing and analysis. It has not only high sensitivity, simple structure and stable performance, but also own good flexibility. Various species can be detected by applying different potentials and alter different kinds of electrode. In this subject, on the basis of study of three-electrode system detection’s principle and conventional voltammetric detecting instruments, a two-electrode voltammetric detection system has been designed. In this system, a solid electrode with large surface area and stable electrode potential is acted as counter electrode and the glass reference electrode with inner solution commonly used in three-electrode system has been eliminated. In this study,a serious dxperiment such as the detection of pH value,Ca2+,Cr,H2O2,pb2+ions and caffeine in coffee solution has been carried out by using this two-electrode detecting system.The main study contents and results of this study include some following aspects:(1) On the basis of study of three-electrode system detecting principle and its instrument structure, the characterization of counter electrode in two-electrode system has been proposed, which is stable electrode potential, chemical inert, good conductivity, high mechanical strength, maintainance free and low costs. The two kinds of counter electrode:large surface area stainless steel electrode and active carbon electrode have been designed and fabricated and their characteristics have been studied.(2) A two-electrode system has been developed with a solid ion-selective working electrode and an active carbon counter electrode. pH value and Ca2+and Cl-ions in water can be selective detected via this two-electrode system by using pulse amperometric and cyclic voltammetric detection methods, respectively. The results indicated that, the relationship between the responses of the two detection methods and the testing ion concentrations are linear, with r>0.9970, RSD<1.05%. Comparing with potentiometric detection method, they are both free from charge accumulation interference which is promising in on-line monitoring applications.(3) A miniaturization voltammetric two-electrode detecting instrument has been developed which is composed by electrode probe unit, MCU control unit and software processing unit. MCU control unit has the function of working electrode changing, various potential output, and current responses collecting. Software processing unit has the function of working pattern selection, parameter setting, communication with MCU, current signal display, data analyze and processing, and results displaying according to the algorithm model, This detecting instrument has realized the detection process automation and intellectualization.(4) The application studies of this two-electrode voltammetric detecting instrument have been carried out. Hydrogen peroxide, lead ion and caffeine have been detected. In pulse amperometric hydrogen peroxide determination, the current response is linear with the concentration with r=0.9970, RSD<2.10%. In stripping voltammetric lead ion determination, the stripping peak current is linear with lead ion concentration with r=0.9996, detection limit of1.69ppb. The detecting results indicated that, the sensitivity, detection range and detection limit are all comparable with that of conventional three-electrode detection system. In order to expand the application areas of this two-electrode voltammetric detection system, it has been used in caffeine detection in coffee solution. Strong alkali type ion exchange resin pretreatment has been introduced to eliminated the interference species, enlarge the oxidation peak response of caffeine, increasing the detection sensitivity. The detection sensitivity of caffeine in pretreated coffee solution is44uA/g with r=0.9990.The research result shows that, by the use of the two-electrode voltammetric detecting instrument, combine with different detection methods and different electrode probe, various species such as pH value, mineral ions and micromolecules can be detected. This detecting instrument has high detection accuracy, good stabilization, simple structure, low cost, long lifespan, maintenance-free, easy tominiaturization, automation and intellectualization, which are turns out promising on water property monitoring in domestic applications.更多还原