Polysulfone composite membranes

Feng, X.S. Huang, R.Y.M. Pervaporation with chitosan membranes I. Separation of water from ethylene glycol by a chitosan/polysulfone composite membrane. J. Membr. Sci. 1996, 116, 67-76. 

Zhang, Y, Shan, L., Tu, Z. and Zhang, Y 2008. Preparation and characterization of novel Ce-doped nonstoichiometiic nanosUica/polysulfone composite membranes. Sep. Purif. 

Huang, R.Y.M., Pal, R. and Moon, G.Y. 1999. Crosslinked chitosan composite membrane for the pervaporation dehydration of alcohol mixtures and enhancement of structural stability of chitosan/polysulfone composite membranes. 

L. Liu, A. Chakma, X. Feng, Preparation of hollow fiber poly(ether block amide)/polysulfone composite membranes for separation of carbon dioxide from nitrogen, Chem. Eng. J., 105,... 

Two polyamide/polysulfone composite membranes, a commercial membrane (C-PA) and an experimental one (PAO) are studied in this Chapter. The polysulfone support of sample C-PA is the porous P-PS membrane previously studied. The roughness of both polyamide membranes is higher than that of other studied membranes, being the experimental composite membrane more than three times rougher than the commercial one (Ra(C-PA) = 25.0 nm and Ra(PAO) = 81.7 nm obtained from 15 jm AFM images), as can be observed in Figme 9 AFM images. 

Acid activated composite membranes were experimentally prepared in the same way than the experimental PAO polyamide/polysulfone composite membrane. Different concentrations of di-(2-ethyl hexyl)dithiophosphoric acid (DTPA) were added to interfacial-polymerization monomer solutions. Molecular structure of this organic acid is shown in Scheme 4. This activating agent is expected to be the carrier for heavy metallic ions, such as thallium, cadmium, zinc or uranium, between the media at both membrane sides [8-9, 63-65]. In this chapter, two activated membranes are studied DT50 and DT200 fabricated from 50 and 200 mM acid solutions, respectively. 

In order to correlate chemieal analysis of aetivated membrane surface with other characteristic parameters, tangential streaming potential measurements at a constant NaCl concentration (5x10 " M) but different pHs were carried out with the DT200 sample and analysed using the local dissociation model [68-69], which allows the determination of the pKa and the munber of acid sites accessible on the membrane surface (N ), and their comparison with the same parameter for PAO polyamide/polysulfone composite membrane (the un-modified base membrane). The obtained values and surface roughness are ... 

Polysulfone composite membranes provide a different chemical composition and structure to some of the examples shown. A polysulfone composite membrane is shown by SEM of cross sections (Fig. 5.27A and B) and of the top surface (Fig. 5.27C). A porous texture is seen (Fig. 5.27A) with larger macrovoids near the bottom surface. There is an open porous structure with a pore... 

Fig. 5.27 A polysulfone composite membrane is shown in both cross section (A and B) and surface views (C). SEM images reveal large macrovoids on the bottom side of the membrane within a porous texture support layer. A dense surface layer (arrow) appears to be composed of granular particles of polymer with little pore volume. Some surface porosity is seen (C) but these pores are considerably smaller than those observed in the bulk of the membrane. Chemical etching of the top surface results in removal of the active surface (D), which gives another view of the bulk porous morphology.

Figure 7.2 Scanning electron microscopy images of polysulfone composite membrane for carbon nanotubes active surface (a) and porous surface (b) and for the polysulfone membrane synthetized with Tween 80 surfactant active surface (c) and porous surface (d). All microscopies are effectuated at xlOO.

Polysulfone composite membranes provide a different chemical composition and structure compared with some of the examples shown. A polysulfone composite membrane is shown by SEM of cross sections (Fig. 5.42A, B) and of the top surface (Fig. 5.42C). A porous texture is seen (Fig. 5.42A) with larger macrovoids near the bottom surface. There is an open porous structure with a pore gradient, with smaller pores nearer the dense top surface (Fig. 5.42B). The asymmetric membrane has very fine surface pores, about 0.05-0.2/im across (Fig. 5.42C) with an underlying open network composed of string of polymer. The surfaces of composite membranes are generally dense, and SEM micrographs may not reveal any resolvable surface pores. Chemical etching of this dense surface layer is useful to observe the porous substructure (Fig. 5.42D). 

Wang, X. Li, M. Golding, B. T. Sadeghi, M. Cao, Y Yu, E. H. Scott, K., A polytetrafluoroethylene-quatemary l,4-diazabicyclo-[2.2.2]-octane polysulfone composite membrane for alkaline anion exchange membrane fuel cells. International Journal of Hydrogen Energy 2011, 36(16), 10022-10026. 

Polydimethylsiloxane has been investigated systematically for the removal of different solvents from air or nitrogen [62], The PDMS-polysulfone composite membranes for acetone-air separation could be implemented in a solvent recovery unit with a return of investment in less than two years [63], Capillary membrane modules for the removal of organic toluene and ethyl acetate from could be an economical alternative to the conventional processes within certain ranges of purity and flow [64]. Silicone polymers modified by a combination of fluorination and crosslinking exhibit an improved chemical resistance of the membranes to some hydrocarbons such as gasoline [65]. 

Zhou, Y, Zhao, H., Bai, H., Zhang, L., and Tang, H. 2012. Papermaking effluent treatment A new cellulose nanocrystalline/polysulfone composite membrane. Procedia Environ. Sci. 16 145-151. 

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