Fabrication And Application Research Of Three Novel Phenols Electrochemical Sensors

Phenol is a kind of persistent organic pollutant that will cause serious soil and water pollution. Monitoring the content of phenol has great significant not only to human health but also environment protection. There are many methods for detection and analysis of phenols, in which the electrochemical method is widely used for the detection of a variety of phenolic compounds due to its advantages of high sensitivity and simple operation. And the construction of a novel sensing interface is the key for electrochemical detection. In this paper, the novel sensing interface based on three kinds of chemically modified electrodes are constructed, and used for electrochemical detection of phenols in environmental pollutants. This study provides a new idea for the detection of phenolic substances in the environment with high sensitivity and selectivity, it also has a certain scientific significance for extending its application in the environmental monitoring, waste management and clinical toxicology research. The main points of our thesis are presented as follows:1. A poly-beryllon II film modified carbon paste electrode(PBL-II/CPE) has been constructed by electropolymerization method. Electrochemical characterization of the PBL-II/CPE was investigated by electrochemical impedance spectroscopy(EIS). The electrochemical behaviors of pyrocatechol(PC) and hydroquinone(HQ) were investigated by cyclic voltammetry(CV). In addition, the modified electrode exhibits a good selectivity towards the simltaneous detection of PC and HQ. By using differential pulse voltammetry(DPV) method, low detection limits of 0.8 μ mol/L for PC and 1.0 μ mol/L for HQ were obtained(S/N = 3), respectively. Meanwhile, the electrode was successfully used for the determination of PC and HQ in local tap water sample and the results are satisfactory.2. Nanometer lanthanum hydroxide was synthesized by hydrothermal method. A new electrochemical sensor of PNA/La(OH)3/CPE is constructed with nano lanthanum hydroxide and nicotinic acid composite film. The electrochemical behaviors of bisphenol A(BPA) on PNA/La(OH)3/CPE was studied by CV and EIS. The results indicated that a synergistic catalytic effect of nanometer lanthanum hydroxide and nicotinic acid on the electrode surface provides a good electrochemical environment for BPA and makes BPA perform a high electrochemical activity and catalytic capability. The linear relationship between the peak current and BPA concentration was obtained in the range from 0.05 to 65 μmol/L and the detection limit was 0.02 μmol/L(S/N = 3). The method has characteristics of low detection limit, high sensitivity and wide linear range which makes it better than the traditional electrode.3. First of all, the carbon nanotubes modified carbon paste electrodes(CNT/CPE) was fabricated by dropping-coating method. Then the gold nanoparticles(AuNPs) were deposited on the suface of the CNT/CPE by chronoamperometry method and the AuNPs/CNT composited carbon paste electrodes(AuNPs/CNT/CPE) was successfully constructed. The characteristics of the AuNPs/CNT/CPE was obtained by SEM and other electrochemical methods. In 0.1 mol/L PBS(pH=7.0), the electrochemical behavior of BPA on this modified electrode was studied by CV. The study found that AuNPs/CNT/CPE has good electrocatalytic properties towards BPA. The detection limits of BPA was 0.3 nmol/L(S/N=3). Compared with other modified electrodes, this method has properties of lower detection limits and wider linear range. The stability of AuNPs/CNT/CPE and the anti-interference has also been studied, the results are good.