Preparation Of Metal-Complexing Molecular Imprinted Membranes And Their Application Study On Membrane Chromatography

Molecularly imprinted membranes (MIMs) are a kind of membrane which are composed of molecularly imprinted polymers. MIMs, which posses the advantages of both molecular imprinting and membrane technology, have been widely used in the fields of separation, catalysis and sensor technology. In this work,2,2'-dipyridyl-nickel(Ⅱ) and Theophylline-copper(Ⅱ) were used as template, poly(vinylidene fluoride) (PVDF) membrane as supporting membrane and surface coated thermal polymerization method were used to prepare the MIMs. Then modules were assembled to evaluate the MIMs' separation performance. The main results were summarized as follows:Firstly,2,2'-dipyridyl-nickel(Ⅱ) metal-complexing MIMs was prepared. The modified degree and binding capacity indicated that the optimized coating time was 20～30s, in which condition that the binding capacity can reach 3.6μmol/g. Ultrasonic washing 4h was the optimized washing condition to remove all the templates from the MIMs which remarkably increased the binding capacity of washed MIMs.Secondly, metal-complexing theophylline molecular imprinted membranes (MIMs) were prepared and characterized by SEM, which showed that an imprinting layer was formed on the surface of PVDF membrane. The binding capacity was increased in the coordination of Cu2+, from 1.61μmol/g to 2.69μmol/g at THO concentration 0.2mmol/L. The selectivity of THO differentiated from Theobromine (TB) can reach 2.39 at THO concentration 0.15mmol/L. The MIMs preferred showing more binding capacity in the coordination of Cu2+ than Zn2+ and Ni2+. The permeation performance of MIMs showed that at concentration 0.005mmol/L and flow rate 12ml/min, the permeation selectivity of THO/TB can reach 0.36 which means that the THO was mainly adsorbed by MIMs.Finally, the modules were assembled to detect the MIMs' separation performance for THO and TB. The concentrations of the filtration were determined by HPLC. The comparison of cycle time showed that at flow rate 15ml/min the equilibrium time was 150min and the separation factor reached 2.05. Shell pass showed better separation performance than tube pass and the optimized flow rate is 15ml/min.