Preparation And Separation Performance Of Theophylline Molecular Imprinted Ceramic Hollow Fiber Composite Membranes

Theophylline (THO) molecular imprinted ceramic hollow fiber composite membranes were successfully prepared by thermal initiated free radical polymerization on the surface of α-Al2O3ceramic hollow fiber substrate membranes. Molecular imprinted polymerization layer coated on α-Al2O3microporous substrate was synthesized by taking THO as the template molecule, methacrylic acid (MAA) as the functional monomer, ethylene glycol dimethacrylate (EDMA) as the cross-linker, and2,2’-azobisisobutyronitrile (AIBN) as the free radical initiator. The adsorption kinetics and thermodynamics were also investigated. Then MIM modules combined with cross flow filtration were used to evaluate the membrane separation performance. Some problems existed in the preparation and applications of MIM were proposed, which provided theoretical assistance for their industrial applications.Firstly, theophylline molecular imprinted composite membranes were successfully prepared on the surface of ceramic hollow fiber substrate membranes and the preparation conditions were optimized according to the specific recognition properties. Based on the binding experiments, the optimum polymerization condition for the preparation of theophylline imprinted composite membranes was confirmed as1.0mmol THO,4.0mmol MAA,20.0mmol EDMA and0.4mmol AIBN added into20.0mL chloroform and coated upon membranes for3min each time to polymerise twice, then reacted at60℃at vacuum box for24h. The adsorption experiments showed that the support membrane had no recognition selectivity to THO, while MIM had two kinds of adsorption types of nonspecific adsorption and specific adsorption to THO. Besides, the highest adsorption selectivity factor was up to1.94. Contact angle, SEM, FTIR and AFM characterization explained the existence of a1μm dense imprinted layer on the surface of MIM. In addition, the NMR analysis of MIP and NIP displayed that THO molecule was successfully synthesized into the imprinted polymer.Secondly, the adsorption kinetics and thermodynamics of MIM to THO were investigated. The research results showed that the adsorption process of MIM to THO was conducted spontaneously. The binding capacity increased obviously in the first4h and then increased slowly till balance. It also can be found that there were two kinds of binding sites in the self-assembly process of MAA and THO.Finally, the separation permeation applications and regeneration of MIM were studied. It can be seen from the permeation experiments that THO transferred faster than TB through MIM, which was called facilitated permeation mechanism. The MIM separation selectivity factor of THO to TB was2.63. Moreover, the separation performance of MIM was still better than the support membrane after using three times, which laid the foundation for the scale-up research of MIM.