Preparation Of Polypropylene Affinity Membranes By Graft Polymerization And The Adsorption Of Bilirubin

Preirradiated polypropylene membrane has been modified by grafting glycidyl methacrylate (GMA) in an aqueous medium with Cibacron blue (CBD) or trimethylamine (TMA) on the epoxy groups of the GMA chains to prepare the CBD membrane (CBD-g-PP) and the quaternary ammonium cation membrane (TMA-g-PP), which is expected a good adsorption of bilirubin. The grafting copolymerization reaction was studied under different experimental conditions such as total adsorption dose, Mohr's salt concentration and volume, storage conditions, reaction time and temperature, monomer concentration to determine the optimum conditions for affording proper grafting degree. The degree of grafting increased accordingly with the ascending of total adsorption dose within the irradiated permission of the membrane. Low temperature is propitious to the storage of the irradiated membranes and the membranes should be used within 3 days when stored at 0℃ . Higher temperature facilitates the graft polymerization process and 3 hours is the optimum reaction time under 70℃ . The degree of grafting increased accordingly with the rising of the monomer concentration range 0-35%, otherwise the parabola variety. Then we can control the degree of grafting steadily within 200% by the investigation of the factors hereinbefore. We used to control the degree of grafting between 50% and 100% to improving the mechanical strength and keeping the membrane pore configuration. Furthermore, the membrane surface was analyzed by various methods. Serious SEM pictures show the pore configuration keeping well and the process of polymerization through the change on the membrane surface. FTIR analyses showed that the ligands are linked by covalent bond on membranes. The results of chemical detection showed us the CBD-g-PP affinity membranes were good at chemical stability, but the TMA-g-PP membranes were too sensitive to the solvent temperature. The effects on the adsorption of the membranes were investigated. The adsorption capacity increased with the increasing of the ligand content and initial concentration of bulirubin accordingly. And it showed the parabola variety when the pH value of solvent increasing from acid to alkaline, and a peak appeared at pH range 6.0-7.0. Accompanied with the solvent temperature increasing, the adsorption capacity and the rate increased together and we got optimum temperature at 37℃ at the experimental range. The CBD-g-PP membranes still had quite large adsorption capacity although it decreased a lot obviously when adding bovine serum albumin (BSA) in the solvent. The results, the adsorption capacity can be raised to 32.5mg/g in the BSA-bilirubin complex solution of nBSA:nBR=0.4, showed the membrane can achieve a strong competitive ability to adsorb bilirubin from BSA-bilirubin complex solution. And the details need being investigated at the future experiment. The TMA-g-PP membranes were investigated under temperature 4℃ , and we got the approximative results but lower adsorption efficiency when we observing the adsorption capacity changing with the ligand content and initial concentration of bilirubin.