Crosslinked poly(hydroxyethyl methacrylate) membranes for desalination by reverse osmosis

摘要

AbstractA series of crosslinked hydroxyethyl methacrylate (HEMA) membranes for reverse osmosis desalination has been prepared. The crosslinkers used were trimethylol propane trimethacrylate (TPT) or ethylene glycol dimethacrylate (EGD). Membranes were synthesized by polymerizing the monomers as a thin homogeneous film. In addition to reverse osmosis tests, the membranes were also characterized by osmosis experiments and sorption measurements. The reverse osmosis water flux (1500 psi applied pressure, 4 NaCl brine, pH = 5) for these membranes decreases from 0.6 gallonmil/ft2‐day (GMFD) to 0.055 GMFD and salt rejection increase from 78 to a maximum of 94 as the amount of TPT is increased from 0 to 11 mole‐. Water contents decrease from 42 to 15 over the same range of crosslinker, but the preferential sorption of water to salt does not vary. Thus, rises in reverse‐osmosis semipermeability were found to result from changes in water–salt diffusivity ratios. The mechanism of permselectivity has been interpreted in terms of parallel diffusive fluxes across the membrane of primary H‐bonded water and secondary water plus