Polyamide/polysulfone

Membranes UF membranes consist primarily of polymeric structures (polyethersulfone, regenerated cellulose, polysulfone, polyamide, polyacrylonitrile, or various fluoropolymers) formed by immersion casting on a web or as a composite on a MF membrane. Hydrophobic polymers are surface-modified to render them hydrophilic and thereby reduce fouling, reduce product losses, and increase flux [Cabasso in Vltrafiltration Membranes and Applications, Cooper (ed.). Plenum Press, New York, 1980]. Some inorganic UF membranes (alumina, glass, zirconia) are available but only find use in corrosive applications due to their high cost. 

Many membrane materials have been developed and are used for hemodialyzers. Today, these include regenerated cellulose, cellulose acetate, polyacrylonitrile, poly(methylmethacrylate), vinyl alcohol-ethylene copolymer, polysulfone, polyamide, and others. 

An oxidation-resistant polysulfone-polyamide membrane 22 was prepared by the reaction of equimolar amounts of 4,4 -diaminophenylsulfone and terephthaloyl chloride70). After soaking for 75 days at pH 1 2 in a 5 g/1 Cr03 solution, the membrane had a desalting ratio of > 99 % after a 260 hr continuous operation, while... 

Membrane material Polysulfone Polyamide TFC (thin-film composite)... 

Maurya, S. K., Parashuram, K., Singh, P. S., Ray, P, and Reddy, A. V. R. 2012. Preparation of polysulfone-polyamide thin film composite hollow fiber nanofiltration membranes and their performance in the treatment of aqueous dye solutions. Desalination 304 11-19. 

The EIS characterization of the polysulfone-polyamide/PEG membranes was carried out not only to determine separately the contribution of the porous support and the PEG-modified top layer, but also to correlate the electrical changes with the PEG content. Eigure 2.5a shows an SEM micrograph of the cross section of the PS/PA-PEG membrane the porous polysulfone structure and the dense polyamide top layer where the PEG is mainly located can be clearly observed in this figure (Benavente et al. 2005). 

As of 1995, more than 30 different polymer blends were being used in the manufacture of membranes for hemodialysis and hemofiltration (Klinkmann and Vienken, 1995). The various membrane types used for renal replacement therapy can be divided into membranes derived from cellulose (83 percent of 1991 worldwide total) and from synthetic materials (the remaining 17 percent) (Klinkmann and Vienken, 1995). Synthetic membranes have been constructed from such materials as polyacrylonitrile (PAN), polysulfone, polyamide, polymethylmethacrylate, polycarbonate, and ethyl-vinylalchohol copolymer (Klinkmann and Vienken, 1995). In the United States, use of cellulosic materials for membrane construction predominates at around 95 percent of the total number of membranes used (Klinkmann and Vienken, 1995). 

Conventional stirred filtration cells or a specially designed radial-flow cell equipped with a pump can be used. Membranes made of polysulfone, polyamide, cellulose, etc. are suitable. The essential parameters are the molecular mass exclusion rate in wide pH ranges (1-10) and an appropriate permeate flow rate (1-10 ml min ), retentate volume (2-10 ml), and gas pressure (300 kPa is a suitable pressure in most cases). A nominal exclusion rate of lOkgmoH has been shown to be convenient for polymers having a molecular mass between 30 and 50 kg moH. A polymer concentration of 1 % (w/v) in the cell solution is most appropriate for both retention of elements and their subsequent determination in the retentate. 

M. Weber, W. Heckmann, Compatibilization of polysulfone/polyamide-blends by reactive polysulfones-evidence for copolymer formation, Polymer BuUetin 40 (2-3) (1998) 227-234. 

Polysulfone/ polyamide Graphene oxide RO 2000ppmNaCl in water solution [69]... 

Addition of p-cresol formaldehyde (PCF) into phenolic/NBR blends resulted in rednction in the domain size of the dispersed phase and improvement in mechanical properties [244]. PCF resin has an intermediate polarity compared with NBR and resole and can react faster with NBR. Therefore, PCF molecules are likely to be concentrated at the phenolic/NBR interface and act as an external compatibilising agents [245]. Thus compatibility and chemical bonding between NBR and phenolic resin is improved, leading to the enhancement in properties. The other materials used as toughening agents of phenolic resin include elastomers such as natural rubber and nitrile rubber [246, 247], reactive liquid polymers [248] and thermoplastics such as polysulfone, polyamide, polyethylene oxide [249, 250]. 

In principle, for separation of salt from concentrated brine solutions, desahnation techniques common for seawater are suitable. Koyuncu et al. (2004) reported studies on reactive dye/sodium chloride separation using nanofiltration membranes made from polysulfone-polyamide. The emphasis of this research, however, was more directed towards the quality of the purified water than on reclamation of salt or dye. Wenzel et al. (1996) suggested re-use of the bath of a reactive dyeing process containing all auxiliaries after the hydrolyzed reactive dye has been removed by adsorption on activated carbon. The dyes were degraded in an anaerobic digester. 

One of the most interesting applications of XPS is the study of interfaces since the chemical and electronic properties of elements at the interfaces between thin films and bulk substrates are important in several technological areas, particularly microelectronics, sensors, membranes, metal protection and solar cells. Concerning the study of membranes, XPS is now a very common characterization technique in combination with other such as AFM or SEM. Different types of membrane systems have been successfully studied such as polyamide membranes [24], modified polysulfone/polyamide membranes [20], or supported ionic liquid membranes [25] where both the porous support and the ionic liquids are characterized. 

Membranes with diverse structures (porous, dense and composites) and from different materials (regenerated cellulose, polysulfone, polyamide/polysulfone) currently used in filtration processes (Ultrafiltration, Nanofiltration and Reverse Osmosis) and other separation applications were studied. 

Polyethylene, polyester, nylon, acetate, polyacrylonitrile, polybenzobisthiazole, polypropylene, acrylic, aramid Polyethylene, polyester, polypropylene, polycarbonate, polyimide, fluoropolymers, polyurethanes, poly(vinyl chloride) Cellulose acetate, polysulfone, polyamide, polypropylene, polycarbonate, polyimide, polyacrylonitrile, fluoropolymers Polyoxymethylene, polyester, nylon, polyethersulfone, poly(phenylene sulfide) acrylonitrile-butadiene-styrene, polystyrene... 

A study of asymmetric lignosulfonated modified polysulfone-polyamide PS/PA-LS20 membrane was also carried out by IS measurements. Figure 9.14 shows the cross-section SEM micrographs of the PS/PA-LSIO membrane, which were analyzed by using IFME software [52] these results indicate the membrane with a thickness of 92 pm presents an open central zone (porosity of 42%, mean pore radii of 2.95+ 0.13 pm) and a dense top layer of 2.7 pm thickness and (98.00 + 0.08) nm mean pore radii, where the lignosulfonate is mainly located [51]. 

Figure 9.15 (a) Nyquist plot for asymmetric polysulfone/ polyamide-lignosulfinate modified PS/PA-LS20 membrane, (b) Variation with electrolyte concentration of electrical resistance for dense top layer (A) and porous sublayer (A) of PS/PA-LS20 membrane. 

Membranes Cellulose acetate, polysulfone, polyamide, polypropylene, polycarbonate, polyimide, polyacrylonitrile, fluoropolymers... 

HoUow fibers are widely used for filtration, utilizing the semipermeable nature of their capillary walls. In the medical industry, hollow fiber bioreactors are often made from cellulose and synthetic polymers. Cellulose acetate and cuprammonium rayon are the widely used ceUulose-based hollow fibers, while synthetic hollow fibers are often made from polysulfone, polyamide, and polyacrylonitrile. Modifications can be made to these materials to improve their functions by using polymers based on phospholipid, a substance found in the human cell membrane. 2-methaCTyloyloxyethyl phosphoryl-choline (MPC) is a methacrylate monomer with a phospholipid polar group. When MPC-based copolymers are used as additives for polysulfone, protein adsorption and platelet adhesion can be effectively reduced, thereby improving blood compatibility. Cellulose acetate hollow fiber membranes can also be modified with MPC-based copolymers by means of blending or surface coating to obtain improved permeability. 

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