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Researches On Micro Electrochemical Sensors And Automatic Analysis Instruments For Heavy Metal Detection In Aqueous Environment

Posted on:2013-12-20Degree:DoctorType:Dissertation
Country:ChinaCandidate:W CaiFull Text:PDF
GTID:1228330395993066Subject:Biomedical engineering
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In recent years, the environmental pollution in China has become rather serious with the rapid development of economy. Emission of industrial wastewater and overexploitation of metallic minerals strengthens the heavy metal pollution in aqueous environment. For the dissolved heavy metal ions in water are generally colorless and tasteless, it is difficult to be discovered by senses of vision, smell and taste. Since heavy metals of cumulative effect in the body would do a lot of harm to humans, animals and plants, the technique of quick and in-situ heavy metal detection in aqueous environment is of great significance.In this thesis, electrochemical stripping voltammetry (SV) was selected as an effective method for the in-situ measurements of heavy metal ions in aqueous environment and its principle and quantitative skills are illustrated. We also did researches on the three main development trends which are creative sensing materials, micromation and integration for the sensors focusing on stripping voltammetric detection of heavy metals. Besides that, an automatic monitor and a wireless analysis instrument were developed respectively for the heavy metal detections in the Bohai Sea and the Taihu Lake. The researches were financed by the National High Technology Research Program (863Program) and the National Key Basic Research Program (973Program).The major contents of this thesis are as follows:1) Heavy metals including zinc, cadmium, lead and copper ions in aqueous sample were determined by the mercury-film electrode using differential pulse stripping voltammetry (DPSV) with the analysis instrument fabricated by our lab. Specific detection methods were applied depending on the backgrounds of the solutions. The accuracy of measuring pure water-background samples was good and the precision achieved5%while the precision of measuring seawater-background samples was about15%. The detection limits of all the four elements were in the range of0.1-0.3μg/L. 2) For the trend of creative sensing materials in developing electrochemical sensors, in-situ coated bismuth electrode was tested for heavy metal detection and the method of detecting pure water-background samples was determined. The method of detecting heavy metal ions in seawater by bismuth electrode was also studied. Attractive characteristics of bismuth electrodes are mercury-free and environmentally friendly.3) For the trend of micromation in developing electrochemical electrodes, a microband electrode array consisted of100microelectrodes was developed. The microband electrodes with inter-electrode spacing of64μm were8mm long,6μm wide and100nm thick. The microband electrode array with excellent dimensional and voltammetric traits did good performance in the detection of mixed samples of lead and copper ions.4) For the trend of integration in developing electrochemical electrodes, a photoelectric integrated sensor combined light addressable potentiometric sensor (LAPS) and microelectrode array (MEA) on the same silicon chip was designed and fabricated. It was possible to take respective advantages of LAPS and MEA according to different conditions of the measurements. When LAPS and MEA were applied together to the detection, the linear regression model was built to improve the anti-interference ability.5) Based on the researches on sensors and combining the techniques of automation and chemical analysis, an automatic heavy metal monitor for seawater was developed. All the parameters of the monitor passed the third party test. The automatic heavy metal monitor experienced a number of sea trials and filled the vacancy of in-situ heavy metal monitor for seawater in China.6) By integrating techniques of traditional heavy metal detection and wireless communication, a wireless heavy metal analysis instrument was developed. The optimized water path greatly improved the portability. Preliminary test showed that the instrument functioned well and satisfied the requests of the design.
Keywords/Search Tags:Heavy metal detection, Stripping voltammetry (SV), Heavy metalsensitive film, Microelectrode array (MEA), Photoelectric integrated sensor, Analysisinstrument, In-situ monitoring, Wireless monitoring
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