镉离子(Ⅱ)印迹复合膜的研制及传质机理研究

Preparation and mass transfer mechanism of cadmium ion(Ⅱ)imprinted composite membrane

以Cd(Ⅱ)为印迹离子,采用表面印迹法,对基膜种类、功能单体的种类和用量、致孔溶剂的种类及比例、交联剂的用量及基膜浸泡时间等实验条件进行了优化,优化出制备Cd(Ⅱ)离子印迹复合膜(Cd(Ⅱ)-IICMs)的最佳实验条件,制备了26种Cd(Ⅱ)离子印迹复合膜(Cd(Ⅱ)-IICM1-26)及对应的非印迹复合膜(NCM1-26)。在最佳实验条件制备的Cd(Ⅱ)-IICM6,其吸附量为376.98mg/g,印迹因子为1.56。采用氮气吸附(BET)和扫描电镜(SEM)表征了Cd(Ⅱ)-IICM6和IICM6的结构,使用Langmuir模型和Freundlich模型对其吸附行为进行线性拟合,并结合电感耦合等离子体发射光谱仪(ICP-OES)研究了它们的渗透选择性。结果表明:Cd(Ⅱ)-IICM6对Cd(Ⅱ)的吸附行为符合Freundlich等温吸附模型和准二级动力学模型,吸附过程主要以双分子层吸附和化学吸附为主。在“竞争离子”Co(Ⅱ)、Ni(Ⅱ)和Cu(Ⅱ)的存在下,Cd(Ⅱ)-IICM6对Cd(Ⅱ)具有良好的渗透选择性,其传质机理符合Piletsky的“门”模型,说明Cd(Ⅱ)-IICM6有望用于复杂样品中Cd(Ⅱ)的分离与富集。

Using Cd(Ⅱ)as imprinting ion,the experimental conditions such as the type of base film,the type and amount of functional monomer,the type and ratio of porogen,the amount of crosslinking agent and the soaking time of base film were optimized by surface imprinting method.The optimal experimental condition for the preparation of Cd(Ⅱ)ion imprinted composite membranes(Cd(Ⅱ)-IICMs)was obtained.26 kinds of Cd(Ⅱ)ion imprinted composite membranes(Cd(Ⅱ)-IICM_(1-26))and corresponding non-imprinted composite membranes(NCM_(1-26))were prepared under the optimal conditions.The adsorption capacity of Cd(Ⅱ)-IICM_(6) reached to 376.98mg/g and an imprinting factor was 1.56.Nitrogen adsorption(BET)and scanning electron microscopy(SEM)were used to characterize the structures of Cd(Ⅱ)-IICM_(6) and IICM_(6).The Langmuir model and Freundlich model were applied to linearly fit their adsorption behavior,and the inductively coupled plasma emission spectrometer(ICP-OES)was taken to study their permeation selectivity.The research results showed that the adsorption behavior of Cd(Ⅱ)-IICM_(6) for Cd(Ⅱ)conformed with the Freundlich isotherm adsorption model and the quasi-second-order kinetic model,and the adsorption process was mainly bilayer adsorption and chemical adsorption.In the presence of“competitive ions”Co(Ⅱ),Ni(Ⅱ)and Cu(Ⅱ),Cd(Ⅱ)-IICM_(6) possessed good permeation selectivity for Cd(Ⅱ),and its mass transfer mechanism conformed to Piletsky's“gate”model,indicating that Cd(Ⅱ)-IICM_(6) was expected to be used for the separation and enrichment of Cd(Ⅱ)in complex samples.