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Novel electrochemical sensor and its application for the detection of heavy metals in water

Author: XingSuJie
Tutor: JinLiTong
School: East China Normal University
Course: Analytical Chemistry
Keywords: Electrochemical sensors Heavy metal detection Amperometric Nanocomposites
CLC: X832
Type: Master's thesis
Year: 2010
Downloads: 461
Quote: 1
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Abstract

With the rapid development of industrial and agricultural production, water pollution problem is getting worse, which is the most important heavy metal pollution substances. Heavy metals can accumulate in the water body and crop residues into the human body through the food chain accumulation, constitute a potential hazard to humans. Excess heavy metals in the human body, it will lead to various diseases. Water weight metal contamination problem has attracted worldwide attention and in-depth research on the different types of heavy metal contamination of food and water monitoring and analysis, for the evaluation of water quality, the protection of human health and the maintenance of social and economic sustainable development has important practical significance. Nanomaterials are defined in three-dimensional space in at least one dimension in the nanometer size range 1 ~ 100nm, or by their material composition as the basic unit. Nanocomposites of two or more different materials in different ways nano material combination. Although the composite material from the advent of so far only a few 10-year history, but because it can play a variety of constituent materials advantages and overcome the shortcomings of a single material, it has been widely used, known as the 21st century's most promising materials. With the development of nanotechnology, nano-composite materials as a new type of electrode materials in electrochemical detection and analysis of growing concern by the people. This paper was prepared and characterized a series of novel chemically modified electrode, while the ultrasound, template electrochemical deposition techniques introduced in heavy metals in water and then put forward a new method for determination. The method is simple, rapid, high sensitivity for the detection of heavy metals provides a new concept and ideas. The thesis is divided into five chapters: Chapter Introduction This chapter introduces the main system of heavy metal pollution hazards and detection technology development, chemically modified electrode preparation and application of synthetic nanocomposites ultrasound principles and applications. Research in these areas and with the progress made and reviewed. Chapter II Prussian Blue modified glassy carbon electrode used in water trace Cr (Ⅵ) detection of this chapter was prepared by electrochemical deposition of Prussian blue, and trace amounts of water as a working electrode used in Cr (Ⅵ) detection research. Prussian blue in a certain potential role of redox reactions occur, restore it back into a neutral state when the catalytic Cr (Ⅵ) reduction of Cr (Ⅲ). This experiment examines the Prussian blue film thickness reduction potential, electrolyte on Cr (Ⅵ) reduction response current size. The linear range of 0.5-200ug / L, sensitivity was 15 ± 0.2 nA / ppb, calculated detection limit of 0.15ug / L. This test method by the coexistence of metal ions and surfactants affected. This method is simple preparation, stability, short analysis time. Chapter AgNPs / Nafion nanocomposite electrode and used water trace Cr (Ⅵ) Detection chapter of Ag nanoparticles modified Nafion membrane composite electrode as the working electrode amperometric detection using direct detection in water bodies Cr (Ⅵ ). Nafion cation exchangers can be used as a conductive soft template, the Ag nanoparticles firmly fixed on the electrode surface, and the electrodeposition of the Ag nanoparticles obtained uniform size, uniform distribution, shows excellent catalytic performance. This AgNPs / Nafion nanocomposite electrodes Cr (Ⅵ) reduction has remarkable sensitivity and selectivity. Cr (Ⅵ) The linear range for 2-230ug / L, sensitivity 1.1nA/ppb, the detection limit was 0.67ug / L. Scanning electron microscope (SEM), transmission electron microscopy (TEM) of AgNPs / Nafion nano composite electrode morphology characterization. By cyclic voltammetry (CV) investigated AgNPs / Nafion nanocomposite electrode electrochemical properties. Results surfaces prepared using this electrochemical AgNPs / Nafion nanocomposite electrode has a greater electrical activity in the area and more excellent electro-catalytic properties. Successfully applied this nanocomposite electrode amperometric detection of trace Cr (Ⅵ) study. Chapter ultrasonic synthetic Au / NHAP nano-composite material used in the detection of lead and cadmium in water to precipitate this chapter synthesized nanoscale bio-ceramic hydroxyapatite as a template, under ultrasonic irradiation, synthesis of Au / NHAP nanocomposite applied to the actual water samples for lead and cadmium testing. This by transmission electron microscopy to characterize the morphology of the composite. Hydroxyapatite nano particle size uniformity, preventing agglomeration of gold nanoparticles, two kinds of lead and cadmium metal particles have specific adsorption. This detection method using adsorption - Restore - Dissolution independent solution environment, effectively ruled out interference from other heavy metal ions. This method is unique and novel, synthetic simple, excellent results, low cost, in the development of new sensors have potential applications. Chapter platinum oxide nanotube array electrodes applied to detect trace amounts of As (Ⅲ) of this chapter describes the platinum nanotubes (PtNTs) electrode array used to detect trace amounts of arsenic oxidation of As (Ⅲ) study. The use of 3 - aminopropyl trimethoxy silane (APS)-modified porous alumina template (PAA) AuCl4-containing solution, using an electrochemical deposition method PtNTs highly ordered array structure. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) on PtNTs array morphology and structure characterization. By electrochemical studies show, PtNTs array structure has a larger effective area and higher catalytic performance. And Pt nanoparticles modified glassy carbon electrode (Pt-NPs/GC) and Pt disk electrode compared, PtNTs electrode array to detect trace amounts of arsenic oxide (Ⅲ) has a better performance. 50 replicate measurements 20μM Arsenic (Ⅲ) with relative standard deviation (RSD) was 3.5% and the detection limit (S / N = 3) was 0.1μg / L, than reported in the literature Pt-NPs/GC and Pt disk electrode low a -2 orders of magnitude, prove that this method has a higher sensitivity for trace amounts of As (Ⅲ) routine testing has potential application value.

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