Preparation Of Immobilized Cu²⁺ Nylon-Based Affinity Membranes And Their Separation Performance

The chelating metal affinity membrane is paid great attention for its wide sources,high selectivity,large permeation flux and so on.The adsorption performance of bovine serum albumin(BSA),as target protein,by the prepared immobilized Cu²⁺ nylon-based affinity membranes was deeply studied in this paper. The research in the whole paper is focused on the following three parts:membrane preparation,mathematical model building and model validation.A nylon-based affinity membrane immobilized copper ion was prepared using hydrochloric acid as hydrolytic solution,N,N'-carbonyldiimidazole(CDI) as activating agent, iminodiacetic acid(IDA) as coupling agent and copper ion as immobilized metal ion.The results show that the amount of -NH₂ of membrane can reach 90.0μmol/g dry membrane after the nylon 66 membrane is immersed in 1mol/L hydrochloric acid at 55℃for 72h.And the amount of activated -NH₂ could achieve 74.9μmol/g after immersed in 0.5g/100ml CDI at 50℃for 2～4h.When the coupling condition is 9.0g/100ml IDA at 40℃for 15h,21.4μmol/cm² copper ions are immobilized.A mathematical model including diffusion,convection and Freundlich adsorption kinetics was formulated to analyze the design and operation of the chelating metal affinity membrane adsorption of BSA,which is solved by the coefficient mode of PDE method.It can be used to predict the effects of model parameter variation on membrane performance efficiently and exactly,such as breakthrough time,saturated absorption time and so on.We investigated the effects of initial concentration of BSA and pH value on adsorption of BSA.The results show that higher initial concentration and pH value are favorable to adsorption of BSA,and the approximate maximum adsorption capacity for BSA can reach 74.3mg/g dry membrane.Lastly,the affinity membrane model was validated experimentally, based on the adsorption performance of BSA to immobilized Cu²⁺ affinity membranes. Adsorption equilibrium and kinetic parameters are measured in batch experiments.The measured parameters are used in the affinity membrane model for the comparison with experimental breakthrough curves.