The Preparation And Application Of Chemical Modified Electrode Based On Conducting Polymers Composites In Determination Of Pb(Ⅱ)

In this paper, the Na+-montmorillonites/polyaniline nanocomposite modified glassy carbon electrode(PANI/MMT/GCE), sepilote/polypyrrole/nafion nanocomposite modified glassy carbon electrode(Ppy/Sep/nafion/GCE), and graphene/polyaniline/gold nanoparticle composite modified glassy carbon electrode(nanoAu/GR/PANI/GCE) were prepared respectively. The electrochemical behavior of Pb2+ was studied at these modified electrodes and analytical application potential of conducting polymer based composite modified electrode in the detection of heavy ions were studied. The main results are as follows:1. The PANI/MMT nanocomposite was prepared by in situ polymerization of aniline on the surface of Na+-montmorillonites and used to prepare PANI/MMT modified glassy carbon electrode. The electrochemical behavior of Pb2+ was studied at the modified electrode by differential pulse anodic stripping voltammetry. The experimental conditions such as the electrolyte concentration, the p H, the amount of modified suspensiton, the feeding ration of aniline and montmorillonite, the accumulation potential and time were optimized. Under the optimal experimental condition, the stripping peak currents show good linear relationships with Pb2+ concentration in the range of 4~100 nM with the correlation coefficient of 0.998 and the detection limit is 1 nM. This method can be used for real water samples for the detection of lead ions.2. The Ppy/Sep modified composite was prepared by polymerization of pyrrole on the surface of sepilote and characterizated by scanning electron microscopy, FTIR, and electrochemical techniques. The electrochemical response of Pb2+ on the Ppy/Sep/Nafion composites modified electrode was studied by differential pulse anodic stripping voltammetry. The experimental results showed that the electrochemical response of lead ions could be enhanced greatly on the modified electrode, which can be used in the sensitive detection of lead ions. Under the optimal experimental conditions, the stripping peak currents show good linear relationships with Pb2+ concentration in the range of 4~800 nM with the correlation coefficient of 0.9997 and the detection limit is 0.1 nM. In real water samples, the recoveries of lead ions are in the ranges of 98.4 ~98.8%, and the relative standard deviation is less than 4.5%.3. The PANI/GR composite was prepared through the polymerization of aniline in the presence of graphene and the AuNPs/PANI/GR composite was prepared by depositing gold nanoparticles on the surface of PANI/GR. The AuNPs/PANI/GR /GCE was characterized and used in the dection of Pb2+ by differential pulse anodic stripping voltammetry. The electrochemical response of Pb2+ could be enhanced significantly on the AuNPs/PANI/GR/GCE. Under the optimal condition, the stripping peak currents show good linear relationships with Pb2+ concentration in the range of 5~100 nM with the correlation coefficient of 0.998 and the detection limit is 1 nM.. The modified electrode was successfully applied in the determination of trace Pb2+ in real water samples and the statisfactory results were obtained.