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The Preparation of Nanomaterials Chemical Modified Electrode and Their Application in the Environmental Analysis

Author: LianYuanYuan
Tutor: QiGuangCai
School: Yan'an University
Course: Analytical Chemistry
Keywords: Chemically modified electrode Nanomaterials Environmental analysis over-oxidized polypyrrole
CLC: X830.2
Type: Master's thesis
Year: 2011
Downloads: 280
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Abstract


Chemically modified electrode was a hot research field of the electrochemical and electroanalytical chemistry, and nano-materials had been received extensive attention for its unique physical and chemical properties in analytical chemistry. So nanomaterial chemical modified electrode had aroused great interest of researchers with its high sensitivity, high selectivity and easy miniaturization and other characteristics, and which had achieved extensive attention in many fields including environmental electrochemical analysis, biologic electrochemical analysis, medical analysis, clinical determination and so on. To improve the electrocatalytic performance and stability of the chemical modified electrodes, simplified modification procedure and improve modified electrode reproducibility were currently one of the problems to be solved. In this paper, carbon ceramic composite electrodes was based electrodes, kinds of nanomaterials including Ppyox, CoHCF, PB, Pd, Au and CeO2 modified electrodes were prepared by electrochemical methods. The electrochemical behavior and electrocatalytic activity of environmental substances （bisphenol A, hydrazine, dihydmxybenzenes isomers, phenol and hydrogen peroxide） on the above electrodes were investigated, the corresponding electrochemical detection methods were established which had high sensitivity and selectivity. The research possessed of potential application values in improving the stability and broaden the electroanalytical chemistry of modified electrodes.This thesis mainly studied the preparation and electrochemical activity of the following modified electrodes. The main contents were described as follows:1. The electrochemical performance of three dihydmxybenzenes isomers （hydroquinone, catechol and resorcinol） was investigated at the Ppyox/CCE electrode by cyclic voltammetry. Results showed that, in 0.05 mol·L-1 phosphate buffer solution of pH 7.0（PBS）, the Ppyox/CCE electrode showed excellent electrocatalytic activity and selectivity for dihydmxybenzenes. Under the optimal conditions, the calibration curves showed good linear relationship for three dihydroxybenzenes in the range of 1.0×10-6 5.0×10-4 mol·L-1 and their detection limits were 2.0×10-7 mol·L-1. The proposed method was successfully applied in the determination of dihydroxybenzenes in simulated water samples.2. A new method was put forward which was direct electrochemical method prepared nano-structure of polynuclear metal hexaeyanoferrate. In solution, EDTA could controll the effective concentration of metal ion, thus which which had been produced and thus speeded up the rate of polynuclear metal hexaeyanoferrate deposition. A cobalt hexacyanoferrate / overoxidized polypyrrole membrane modified electrode （CoHCF/Ppyox/CCE） was fabricated by using the electrochemical deposition method. The electrochemical behavior and electrocatalytic activity for N2H4 at this modified electrode was also investigated. The results showed, The CoHCF/Ppyox/CCE modified electrode had strong electrocatalytic oxidation activity for N2H4. Under the optimum conditions, the linear range was 2.0×10-6 mol·L-1 to 1.2×10-3 mol·L-1 with the detection limit of 6.0×10-7 mol·L-1 （3sb）. The sensitivity was 117.9μA·(mmol·L-1)-1. This method has been applied in the determination of N2H4 in stimulant water samples.3. Nano-Prussian blue was deposited on the surface of Ppyox/CCE electrode by the layer-layer assembling method in K3Fe（CN）6 and EDTA mixed solution. The electrocatalytic activity for H2O2 at this modified electrode was investigated. The results showed, The PB/Ppyox/CCE had strong electrocatalytic oxidation activity for H2O2. Under the optimum conditions, the linear range was 2.0×10-6 mol·L-1 to 1.6×10-3 mol·L-1 with the detection limit of 3.3×10-7 mol·L-1 （3sb）. The sensitivity was 76.87μA·(mmol·L-1)-1.4. A Pd nanoparticles modified ceramic carbon composite electrode （CCE） was fabricated by using the single controlled-current chronopotentiometry method and characterized with cyclic voltammetry and SEM. The electrochemical activity of H2O2 at Pd/CCE was investigated. The results showed the Pd/CCE had high electrocatalytic oxidation activity for H2O2. Under the optimum conditions, the linear range was 2.0× 10-6 mol·L-1 to 2.6×10-3 mol·L-1 with the detection limit of 5.0×10-7 mol·L-1 （3sb）. The sensitivity was 143.8μA·(mmol·L-1)-1. The proposed electrode had been used for amperometric detection of H2O2 in disinfectant sample.5. An Au/Ppyox/CCE modified electrode was prepared by the layer-layer electrochemical deposition method. The electrochemical behavior of bisphenol A （BPA） at Au/Ppyox/CCE modified electrode was studied. The results showed that, this modified electrode has strong electrcatalytic activity for the oxidation of BPA, Under the optimum conditions, the oxidation peak current and the concentration of BPA was linear between 2.0×10-7 2.0×10-4 mol·L-1. The detection limit was 1.0×10-8 mol·L-1.6. CeO2 nanoparticles were prepared by solid-state reaction and characterized by UV-Vis and XRD spectra. The electrochemical behavior of bisphenol A and phenol on a CeO2 modified carbon paste electrode was studied with cyclic voltammetric and linear sweep voltammetric method. Results showed that, in 0.01 mol·L-1 sodium borate solution of pH 9.18, an irreversible oxidation peak of BPA was observed at + 0.40 V and phenol was observed at + 0.56 V （vs. SCE）. Under the optimal conditions, the linear range was 5.0×10-8 3.0×10-5 mol·L-1 with a detection limit of 2.0×10-8 mol·L-1 for BPA. The linear range was 1.0×10-7 2.0×10-4 mol·L-1 with a detection limit of 5.0×10-8 mol·L-1 for phenol. This method showed a good repeatability and high sensitivity, and could be applied in the determination of BPA and phenol.

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CLC: > Environmental science, safety science > Environmental Quality Assessment and Environmental Monitoring > Environmental monitoring > General issues > Monitoring and analysis methods
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