Fabrication Of Molecularly Imprinted Polymer Based On β-cyclodextrin Modified Magnetic Chitosan For Selective Removal Of Bisphenol A From Aqueous Solution

Bisphenol A(BPA)is mainly used in the industrial production of polycarbonate plastic(PC),epoxy resin,flame retardants and other chemical products.With the widespread using of BPA,it is detected in many waters.As an endocrine disruptor,it is harmful to the reproduction,development and nervous system of human.However,BPA is difficult to effectively be removed in complex water because of the limit of adsorption capacity of adsorbents and environmental conditions.Therefore,it is necessary to prepare an adsorbent with strong selective adsorption capacity towards BPA and anti-interference ability.In this study,β-cyclodextrin modified magnetic chitosan molecular imprinted composite was prepared by surface molecularly imprinting technique.And the process of selective adsorption towards BPA and mechanism were investigated.We combined the unique properties of β-cyclodextrin and chitosan.The optimum conditions of adsorption towards BPA,the selective anti-interference ability and the adsorption mechanism were investigated by a batch of experiments.The research work and achievements of this study mainly included the following three parts:The first part is the preparation and characterization of MMIP.In this study,we used BPA as a template molecule,β-cyclodextrin modified magnetic chitosan(CMC)as the imprinting carrier,methacrylic acid(MAA)as the assisted functional monomer,ethylene glycol dimethacrylate(EGDMA)as cross-linker.MMIP was prepared by surface molecularly imprinting technique.And p-cyclodextrin-modified magnetic chitosan non-molecularly imprinted composite(MNIP)was prepared by the same methods but without the adding of BPA.The as-prepared MMIP and MNIP was evaluated and characterized by scanning electron microscopy(SEM),Fourier transform infrared analysis(FTIR),x-ray diffraction(XRD)and vibrating sample magnetometry(VSM).The results showed that BPA was successfully imprinted on the surface of β-cyclodextrin-modified magnetic chitosan carrier,and MMIP showed loosely reticulation.At pH>2.5,MMIP and MNIP were negatively charged.The magnetism of MMIP was 5.938 emu g-1,which showed good solid-liquid separation performance in the mixture.The second part studied the adsorption of MMIP and MNIP towards BPA in solution.The effects of initial pH,adsorption time,initial BPA concentration,temperature and ionic strength on the adsorption were investigated.The selectivity of the materials was evaluated by comparing the adsorption capacity of MMIP and MNIP towards phenol,2,4-dichlorophenol and TBBPA,and adsorption-desorption experiments was conducted to research the recycling performance of MMIP.The results showed that the optimal binding ability of MMIP reached 105.5 m g-1 when the initial pH is 6.0 and the ionic strength is 20 mg g-1.The adsorption equilibrium can be reached in 60 min.In addition,MMIP showed good recognition and selectivity to BPA,and the relative selectivity coefficient of phenol,2,4-dichlorophenol and tetrabromobisphenol A were 11.201,2.011 and 2.896,respectively.The third part researched the selective adsorption mechanism by fitting kinetics and isothermal data via kinetic model and isotherm model.The results showed that the pseudo-second-order kinetic model described the adsorption equilibrium process of MMIP towards BPA well.And the isothermal adsorption process of MMIP was more consistent with the Langmuir isothermal model.