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1、Membrane-based techniques for the separation and purification of Proteins,,Membrane-based techniques for the separation and purification of proteins,Introduction,Pressure-driven membrane technologies,Membrane chromatography,Electrophoretic membrane contactor,,Integrated membrane technologies,CONTENT
2、S,Conclusions,1. Introduction,Definition,Advantage,Application,A membrane can be described as an interphase,usually heterogeneous, acting as a barrier to the owofmolecular and ionic species present in the liquids and/or vapors contacting the two surfaces.,Advantage:(1)selective transport,(2)efcients
3、eparation, (3)not require additives,(4) less energy consumption.,Application:(1)demineralization,(2) desalination/purication of water,(3)bioseparation of fermentation products(4)milk fractionation,(5)decaidication of fruit juices.,Type:(1) microltration (MF),(2) clarication, sterile ltration and ult
4、raltration (UF) ,(3) Nanoltration (NF),(4) High-performance tangential owltration (HPTFF).,,Type,Definition,,,Disadvantage:(a)limitation of the process stream for relatively low conductivity of feed stream, (b) a high-energy requirement, (c) substantial heat production, and (d) changes in the proces
5、s feed due to reaction at the electrodePES is widely used UF membrane material, because of its high rigidity, creep resistance, good thermal and dimensional stabilities. Other types of polymeric UF membranes such as polyacrylonitrile membrane, regenerated cellulose membrane, cellulose acetate membra
6、ne and ceramic membranes.,,2.1.Proteins separation/ purication by MF,2.2.rotein separation by UF,2.3.Advanced UF techniques for proteins separations,2.4.Protein separation/purication by NF,,2.5.Membrane fouling during protein separation by UF and MF,2.1. Proteins separation/purication by MF,Module c
7、onguration of MF include hollow-ber, tubular,at plate, spiral-wound and rotating devices. The two standardmodes of operation are dead-end and cross-ow congurations are shown in Fig. 2. These devices show signicant increases in protein transmission and capacity.,MF is widely used for the separation,
8、purication and clarifying of protein-containing solutions, e.g. for the recovery of extracellular proteins produced via fermentation and for the removal of bacteria and viruses in the nal formulation of therapeutic proteins.,,2.1.1. Advanced MF under electric eld,Much effort is still being devoted t
9、o developing new membrane modules with improved mass-transfer characteristics for UF and MF processes. Electrically enhanced membrane ltration (EMF) is an advanced technique, which consists in superimposing an electrical eld to a conventional embrane ltration unit. In EMF, the electrical eld acts as
10、 an additional driving force to the transmembrane pressure.,Advangtage:(1) selectivity enhancement,(2) improve protein solutions permeation ux,(3)reduce the surface layer of a membrane,,2.2. Protein separation by UF,UF membranes, based on variety of synthetic polymers, have high thermal stability, c
11、hemical resistivity, and restricted the use of fairly harsh cleaning chemicals.,Modules:(1) Hollow ber,(2) at-sheet cassettes,(3) spiral-wound cartridges, (4) tubular modules,(5) enhanced masstransfer devices,,Protein fractionation is rapidly becoming more selective through improvements in membrane
12、and module design.,,2.3.1. Protein separation using charged UF membranes,Charged UF membrane separation process involved both size and charge based exclusion rather than simply size-based separation of protein molecules, as in the case of UF.,Factor:(1) pH values ,(2)ionic strengths,(3) permeate ux,
13、 (4)and system hydrodynamics. Advantange: extremely low fouling due to electrostatic repulsion.,,Material:(1)polyethersulfone, (2)polysulfone, (2)cellulose acetate, (3)regenerated cellulose,(4) poly (ethylene glycol) (PEG) ,(5) poly (furfural alcohol) (PFA).,2.3.2. UF in the presence of electric eld
14、 (electro-ultraltration),The use of electric eld in UF goes back to the rst study carried out by Bechhold by imposing electric eld in UF and utilized a combination of electroosmosis and electrophoresis to purify colloids in an apparatus he called an electro-ultraltration (EUF).,EUF is an effective m
15、ethod to decrease gel layer formation on the membrane surface and to increase the ltration ux, owing to electrokinetic phenomena such as electrophoresis and electroosmosis,Factor:(1) electric eld,(2) solvent ow,,Advantage:(1)enhance the ltration rate ,(2)increases the separation efciency of the UF of proteins .,For this reason, attention has been directed to the use of pulsed electric elds. Advantage:(1) less energy,(2) higher ux ,(3) reducing fouling,(4) restoring high permeation rate.,
