Preparation Of Carrier Membranes And Study On Mechanisms Of Lipophilic Toxins Removal

An asymmetric membrane with finger-like and interlocking pores was made by the phase inversion process using chloromethyl polysulfone as matrix. Aminated and hydroxylated polysulfone membranes were prepared by amination and hydroxylation reaction, respectively. Then bovine albumin (BSA)-fixed membranes were obtained by crossed-linking albumin into porous membrane with 1,1'-carbonyldiimidazole and bisoxirane reagents, respectively.A mathematical model for facilitated transport in asymmetric membranes with fixed site carriers was derived by assuming an instantaneous, microscopic concentraion fluctuation in the membrane. An analogy was employed between the mass transfer for the faciliated transport with fixed carrier membrane and the electron transfer in a resistor-capacitor (RC) circuit. The utility of the model was demonstrated by experimental data, and the sensitivity analysis was carried out to show the effects of the parameters in the model on the facilitating factor. In addition, the optimized carrier concentration in the membrane was determined.The BSA-fixed membranes were used to remove lipophilic toxins, bilirubin, from the simulation plasma. The experimental results showed that the transfer rate of bilirubin was obviously enhanced after fixing albumin into the high-flux asymmetric membrane. The clearance of bilirubin was 43.6%, while blank membrane was only 3.4%.Activated membranes for covalent immobilization of hydroxyethyl cellulose (HEC) and chitosan were obtained by the reaction of microfilitration nylon membrane with activation reagents such as bisxirane, 1,1'-carbonyldiimidazole, epibromohydrin and formaldehyde. Chitosan-nylon composite membrane with two active group (-NH2 and -OH) had a hydrophilic surface and good blood compatibility, so it can be widely used in affinity separation. Immobilization of polylysine (PLL) onto HEC and chitosan-coated membranes via activation reagents provided PLL affinity membrane, respectively.A simple method for quantitative analysis of solid chitosan based on the ninhydrin reaction was achieved by diluting the reaction solution with 50% (v/v)alcohol aqueous solution. The reaction of chitosan with ninhydrin was sensitive and reproducible. Reliability of regressions: .A mathematical model including convection, diffusion and Freundlich adsorption was proposed and solved by finite difference method. It can be well used to explore the effects of axial diffusion, flow velocity, association kinetic and nonuniformities in membrane thickness, porosity and pore size on membrane performance. The results can be used to develop a basis for proper design, operation and application of affinity membrane based separation processes.Such PLL-HEC and PLL-chitosan affinity membranes were tested to adsorb bilirubin from the phosphate buffer solution and simulation plasma. The experimental results showed that they had a high affinity capacity for bilirubin. These membrane can be renewed by washing the membrane with NaOH solution, phosphate buffer solution and albumin solution.