Polysulfone membrane formation

BA1 Barth, C. and Wolf, B.A., Quick and reliable routes to phase diagrams for polyethersulfone and polysulfone membrane formation, Macromol. Chem. Phys., 201, 365, 2000. 

Most of the available commercial microporous membranes such as polysulfone, polyethersulfone, polyamide, cellulose, polyethylene, polypropylene, and polyvinylidene difluoride are prepared by phase inversion processes. The concept of phase inversion in membrane formation was introduced by Resting [75] and can be defined as follows a homogeneous polymer solution is transformed into a two-phase system in which a solidified polymer-rich phase forms the continuous membrane matrix and the polymer lean phase fills the pores. A detailed description of the phase inversion process is beyond the scope of this section as it was widely discussed in Chapters 1 and 2 nevertheless a short introduction of this process will be presented. 

In the past decade, considerable work has been reported on the formation of tubular polysulfone membranes. Such attempts were first described in 1973 by... 

The initial studies by Cadotte on interfacially formed composite polyamide membranes indicated that monomeric amines behaved poorly in this membrane fabrication approach. This is illustrated in the data listed in Table 5.2, taken from the first public report on the NS-100 membrane.22 Only the polymeric amine polyethylenimine showed development of high rejection membranes at that time. For several years, it was thought that polymeric amine was required to achieve formation of a film that would span the pores in the surface of the microporous polysulfone sheet and resist blowout under pressure However, in 1976, Cadotte and coworkers reported that a monomeric amiri piperazine, could be interfacially reacted with isophthaloyl chloride to give a polyamide barrier layer with salt rejections of 90 to 98% in simulated seawater tests at 1,500 psi.4s This improved membrane formation was achieved through optimization of the interfacial reaction conditions (reactant concentrations, acid acceptors, surfactants). Improved technique after several years of experience in interfacial membrane formation was probably also a factor. 

P. Zschocke and D. Quellmatz, Novel ion exchange membranes based on aromatic polysulfone, J. Membr. Sci., 1985, 22, 325 W.H. Daly, Modification of condensation polymers, J. Macromol. Sci., Chem., 1985, A22, 713-728 N. Sivashinsky and G.B. Tanny, Ionic heterogeneities in sulfonated polysulfone films, J. Appl. Polym. Sci., 1983, 28, 3235-3245 M.D. Guiver, G.P. Robertson, M. Yashikawa and C.M. Tam, Funtionalized polysulfone Methods for chemical modification and membrane applications, Membrane Formation and Modification, ACS Symposium Series, ed. I. Pinnau and B.D. Freeman, American Chemical Society, Washington DC, 2000, Vol. 744. 

Zheng, Q.Z., Wang, P and Yang, YN. 2006. Rheological and thermodynamic variation in polysulfone solution by PEG introduction and its effect on kinetics of membrane formation via phase-inversion process. 279(1-2) 230-237. 

Figure 7.1 (a) Schematic representation of a process of selective separation through an asymmetric membrane (b) types of membranes after the pore formation (c) scanning electron micrograph of section of polysulfone membrane (d) types of functionalized membranes. 

WI2 Wijmans, J. G., Kant, J., Mulder, M.H.V., and Smolders, C.A., Phase separation phenomena in solutions of polysulfone in mixtures of a solvent and a nonsolvent. Relationship with membrane formation, Polymer, 26, 1539, 1985. 

REV Reverchon, E. and Cardea, S., Formation of polysulfone membranes by supercritical... 

Roeckel, A., Hertel, J., Fiegel, R, Abdelhamid, S., Panitz, N., and Walb, D. (1986). Permeability and secondary membrane formation of a high flux polysulfone membrane. Kidney Int. 30, 429. Sasaki, M., Hosoya, N., and Saruhashi, M. (2000). Vitamin E modified cellulose membrane. Artif. Organs 24(10), 779. 

Geong and coworkers reported a new concept for the formation of zeolite/ polymer mixed-matrix reverse osmosis (RO) membranes by interfacial polymerization of mixed-matrix thin films in situ on porous polysulfone (PSF) supports [83]. The mixed-matrix films comprise NaA zeoHte nanoparticles dispersed within 50-200 nm polyamide films. It was found that the surface of the mixed-matrix films was smoother, more hydrophilic and more negatively charged than the surface of the neat polyamide RO membranes. These NaA/polyamide mixed-matrix membranes were tested for a water desalination application. It was demonstrated that the pure water permeability of the mixed-matrix membranes at the highest nanoparticle loadings was nearly doubled over that of the polyamide membranes with equivalent solute rejections. The authors also proved that the micropores of the NaA zeolites played an active role in water permeation and solute rejection. 

Membranes have been used for affinity chromatography in various formats, such as stacked sheets, in rolled geometries, or as hollow fibers. Materials that are commonly used for these membranes are cellulose, polysulfone, and polyamide. Because of their lack of diffusion pores, the surface area in these materials is as low as it is in nonporous beads. However, the flat geometry and shallow bed depth of membranes keep the pressure drop across them to a minimum degree. This means that high flow rates can be used, which makes these membranes especially well-suited for capturing proteins from dilute feed streams. 

Blanco, J.F., Sublet, J., Nguyen, Q.T. and Schaetzel, P. (2006) Formation and morphology studies of different polysulfones-based membranes made by wet phase inversion process. Journal of Membrane Science, 283, 27-37. 

Membrane and Membrane Design Most membranes are polymers in nature, but some inorganic membranes have become available. The most common membranes are based on polysulfone, cellulose acetate, polyamide, fluoropolymers, and other compounds. Formation of a symmetric membrane structure is an important element in the success of UF/NF membrane separation (16). The other considerations for membrane separation are as follows (1) separation capabilities (retention or selectivity), (2) separation rate (flux), (3) chemical and mechanical stabilities, and (4) membrane material cost. 

Young T-H and Chen L-W. Pore formation mechanism of membranes from phase inversion process. Desalination 1995 103(3) 233-247. Han M-J and Nam S-T. Thermodynamic and rheological variation in polysulfone solution by PVP and its effect in the preparation of phase inversion membrane. J. Membr. Sci. 2002 202(l-2) 55-61. 

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