Reverse polyamides

Wu, S., et al. (1997). Plasma modification of aromatic polyamide reverse osmosis composite membrane surface. J. Applied Polymer Science. 64, 10, 1923-1926. 

Whitworth, T.M., Marinas, B.J., and Fritz, S.J., Isotopic fractionation and overall permeation of lithium by a thin-fihn composite polyamide reverse osmosis membrane, J. Membr. Sci., 88, 231, 1994. 

Fibiger, R.F. et al.. Novel polyamide reverse osmosis membranes, US Patent 4769148, 1988. 

Belfer, S., Purinson, Y., and Kedem, O., Surface modification of commercial polyamide reverse osmosis membranes by radical grafting An ATR-FT-IR study, Acta Polym., 49, 574, 1998. 

Polyamide Reverse osmosis, nanofiltration, dialysis, ultrafiltration, microfiltration... 

During the 1960 s, the DuPont Company screened numerous polymers to determine the suitability of materials other than cellulose acetate for use in reverse osmosis desalination. The results of this work indicated that aromatic polyamides were the "choice as the best polymer type for use in the DuPont commercial permeators".7 The company was most successful in developing an asymmetric aromatic polyamide reverse osmosis membrane in a hollow fine fiber configuration which successfully competed with cellulose acetate in the market place. 

Sodium bisulfite is added to the effluent from the polishing filters to remove residual chlorine which would be harmful to the polyamide reverse osmosis membrane. Sulfuric acid is then added to the filter effluent to adjust the pH to about 6.5 and the pretreated water is routed to the primary reverse osmosis system. 

Elimelech M., Zhu X., Childress A.E., Hong S. (1997), Role of membrane surface morphology in colloidal fouling of cellulose acetate and composite aromatic polyamide reverse osmosis membranes. 

Belfer S, Purinson Y, Fainshtein R, Radchenko Y, and Kedem O, Surface modification of commercial composite polyamide reverse osmosis membranes. Journal of Membrane Science 1998,139,175-181. 

C. Gabelich, K. Ishida, R. Bold, Testing of water treatment copolymers for compatibility with polyamide reverse osmosis membranes. Environmental Progress 2005, 24(4), 410-416. 

R.F. Fibiger, J. Koo D.J. Forgach, R. J. Petersen, D.L. Schmidt, R.A. Wess-LiNG, T. F. Stocker (Filmtec, Dow Chemical) Novel polyamide reverse osmosis membranes. US Patent 4859384, August, 1989. 

H. Zhao, S. Qiu, L. Wu, L. Zhang, H. Chen, C. Gao, Improving the performance of polyamide reverse osmosis membrane by incorporation of modified multi-walled carbon nanotubes, Journal of Membrane Science 450 (2014) 249-256. 

Usually, the casting solution for aromatic polyamide reverse osmosis membranes includes the electrolyte additive, and the composition is near the critical concentration. Then the radius of macromolecular spheres should be nearly equal to 52 X, as indicated by Table 2, and their packing fa.shion is close to the cubic packing. Approximating the square-shaped interstitial void area generated between four neighboring spheres (see Figure 4.11) by a circle of equal area, the effective radius of such interstitial void spaces is 27 A. 

There are some indications that the self-assembly method yields sufficiently stable structures. Kwak et al. (2001) used a self-assembly method for Ti02 nanoparticles with a size of 2 nm for aromatic polyamide reverse osmosis membranes, in view of flux enhancement they applied X-ray photoelectron spectroscopy to observe the stability of the attachment of the nanoparticles and concluded that the adsorbed particles were sufficiently tightly bound to the surface to withstand various washing procedures and even harsh reverse osmosis-operating conditions. 

X.Y. Wei, Z. Wang, Z. Zhang, JJC. Wang, S.C. Wang, Surface modification of commercial aromatic polyamide reverse osmosis membranes by graft polymerization of 3-aUyl-5,5-dimethylhydantoin, 7 Afemfr Sci, 351 (2010) 222-233. 

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