Polyelectrolyte multilayer membranes for desalination of aqueous salt solutions and seawater under reverse osmosis conditions (original) (raw)

2005, Applied Surface Science

Ultrathin, multilayered membranes of polyvinylamine (PVA) and polyvinylsulfate (PVS) were electrostatically adsorbed on a porous polymer (polyacrylonitrile/polyethylene terephthalate) support. Their use for desalination of aqueous salt solutions, diluted and non-diluted artificial seawater was investigated under reverse osmosis conditions. Using 60 layer pairs of PVA/PVS as separating membrane, it was possible to completely reject MgCl 2 and MgSO 4 from feed solutions of 1 and 10 mM concentration independently from the operative pressure applied. The rejection of NaCl and Na 2 SO 4 increased from 84 and 96% at 5 bar to 93.5 and 98.5% at 40 bar, respectively. From diluted seawater (1:10; 1:100; 1:1000), 99 AE 1% of Mg 2+ , 97.0 AE 1% of Ca 2+ , and 92.5 AE 1% of Na + were rejected at 40 bar, and from non-diluted seawater, 98 AE 1% of Mg 2+ , 96.4 AE 1% of Ca 2+ , and 74.5 AE 0.8% of Na + were rejected at 40 bar. The permeation flux J increased linearly with the pressure applied. For a membrane of 60 PVA/PVS layer pairs, a flux value of 4 AE 0.2 L m À2 h À1 was found at 40 bar. The influence of the number of deposited layer pairs on R and J was also investigated. #