Preparation Of Molecularly Imprinted Composite Membrane And Electrochemical Detection Of Pollutants In The Environment

Molecular imprinted films (MIFs) are designed and prepared combining the merits of both membrane separation and molecular imprinting technique which developed in the past few years. Compared with traditional membranes, the MIFs represent high selectivity for the specific substance and high rate of binding templates, with a relative simple disposal procedure. Therefore MIFs has attracted more interests in the development of functionalized films. Electrochemical sensor is one of the most effective and sensitive devices for the determination of compounds with its easy-to-design, miniaturization and automation. Although the application of MIFs is mainly focused on the fields of separation in the past, it could find new applications in other fields once integrated with electrochemical sensor. The purpose of this thesis is to apply the molecular imprinting technique to fabricate the new type of electrochemical sensor for the separation, purification and quantitative detection of pollutants in environment. We prepared the molecular imprinted composite films and electrochemical sensor for chloramphenicol as well as bisphenol A. The main results are summarized as follows:(1) A molecular imprinted composite film was prepared for the quantitative detection of chloramphenicol (CAP) by electropolymerization of pyrrole(PPY) on polyaniline (PAN) modified stainless steel needle(SSN) electrode in the presence of CAP as a template. The morphology and structure of the film were characterized by SEM and IR. Compared with the single-imprinted polymer film, the composite film has many merits, such as template molecule eluting faster, attain adsorption equilibrium more quickly, wider linear range, so it has a good prospect for practical application. A linear relationship between the current and the concentration of CAP was found in the range of5.00×10～81.05×10-6mol/L with a detection limit of2.09×10-9mol/L.(2) A sensor was fabricated by preparing a molecular imprinted membrane of BPA on a graphene nanosheets (GNS) modified glassy carbon (GC) electrode with p-AB A as a functional monomer. The morphology and electrochemistry of the film were characterized by SEM methods. The effects of GNS on the electrochemical response of the senor to BPA were discussed. The results indicate that the unique electronic properties and high adsorption capacity of graphene nanosheets could effectively improve the electron transfer rate on the sensor surface, consequently improving the sensitively of sensor towards BPA.(3)The methods of CV and DPV were used to characterize the electrochemical behaviors of BPA at the modified electrode with the molecuarly imprinted composite film. The influence of some factors on the electrochemical response of the senor to BPA was investigated, such as thickness of the film, time of eluting and adsorbing of BPA, pH of the adsorption solution as well as the concentration of the template and the functional monomer. Under the optimized condition a linear relationship between the current and the concentration of BPA was found in the range of5.60×10-7mol/L～1.10×10-4mol/L mol/L with a detection limit of2.21×10-8mol/L.