Dissertation
Dissertation > Environmental science, safety science > Environmental Quality Assessment and Environmental Monitoring > Environmental monitoring equipment > Other monitoring equipment

Researches on Heavy Metal Ion Selective Sensors and Application for Seawater Analysis

Author MenHong
Tutor WangPing
School Zhejiang University
Course Biomedical Engineering
Keywords Heavy metal ion selective sensor Heavy metal detection Light-addressable potentiometric sensor (LAPS) Ion selective electrode (ISE) Thin film sensor Pulsed laser deposition (PLD) Analysis device Seawater detection Hg Fe Cr
CLC X859
Type PhD thesis
Year 2005
Downloads 735
Quotes 7
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With the extensive development of industrialization, heavy metals distributing comprehensively various waters are severely endangering human health by drinking water, food chain, and biogenic enrichment modes etc. It is urgent to detect heavy metals. The water pollution is aggravating in Chinese sea area, especially in neritic area. Marine ecosystems continue worsening. So the plan to establish national marine ecological environment monitor typical system in-situ was proposed during the Tenth Five-Year Plan. By means of real-time sampling, analysis and detection, seawater quality is monitoring, accordingly the decisions and measures to prevent pollution diffusion are able to be taken in time. On the other hand, heavy metal sensors and detection techniques are also foreland topics to research in the world. Based on the reasons above-mentioned, the researches on heavy metal ion selective sensors and the application in seawater analysis are as major tasks in the thesis and financed by Nation 863 High-tech Project Fund, China-Russia Special Fund in International Cooperation at Nation Nature Science Fund (NSFC) and Zhejiang Province International Cooperation Major Fund.The major contents of this thesis are given in the following aspects.1. A kind of equivalent circuit model on light-addressable potentiometric sensor (LAPS) is proposed and the effects of parameters in the LAPS model are evaluated and anaylzed. By combining electrochemical kinetics theory into semiconductor energy band theory, LAPS theory is reformulated. The results are described, that electrostatic potential including bias voltage in external circuit and electrostatic adherence caused by electrolyte solution ions can change the Fermi energy level of LAPS, thus thickness of space-charge region is changed and photo-induced current is affected, and that specific adsorption caused by ionic exchange can affect the flat band voltage of LAPS, space-charge region and photo-induced current. At last heavy metal thin film LAPS is optimized to design based on the equivalent model and LAPS theory.2. Based on LAPS and pulsed laser deposition (PLD) technique, a kind of iron (III) ion selective thin film sensor with glass state structure has been developed for the firsttime. A kind of ion selective electrode (Fe —ISE) sensitive to iron (III) ion synthesized was studied on it’s characteristic and used as a target of PLD device, correspondingly thin film sensor (Fe—LAPS) with glass state structure sensitive to iron (III) ion was prepared on the surface of LAPS. The Fe—LAPS has a good linearity range of 10-210-(5) mol/L, the slope of calibration curve is 435nA/decade, the limit of determination 6.31X10-6 mol/L, suitable pH range 0 to 2. While the concentration of Fe (III) ion is more than 10-4 mol/L, the response time is less than 30 s, and the concentration less than 10-4 mol/L, no more than 2 min. The calibration curve has good repetitiveness in 8 weeks. The resolution and sensitivity of Fe— LAPS improve 7.69 times than Fe—ISE’s.3. Based on LAPS and PLD technique, a kind of mercury (II) ion selective thin film sensor with crystal state structure had been developed for the first time. A kind of ion selective electrode (Hg—ISE) sensitive to mercury (II) ion synthesized was studied on it’s characteristic and used as a target of PLD device, correspondingly thin film sensor (Hg—LAPS) with crystal state structure was prepared on the surface of LAPS. The Hg—LAPS has a good linearity range of 10-310-6 mol/L, the slope of calibration curve is 46.5 nA/decade, the limit of determination 3.44x10-7 mol/L, suitable pH range 1 to 3. While the concentration of Hg (II) ion is more than 10-5 mol/L, the response time is less than 40 s, and the concentration less than 10-5 mol/L, no more than 2 min. The calibration curve has good repetitiveness in 2 weeks. The resolution and sensitivity of Hg—LAPS improve 1.53 times than Hg—ISE’s.4. Based on LAPS and PLD technique, a kind of chromium (VI) ion selective thin film sensor with glass state struct

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