(434a) High-Flux Reverse Osmosis Membranes for Brackish Water Desalination

High-Flux Reverse Osmosis Membranes for Brackish Water
Desalination

Lin
Zhao, C.-Y. Chang, and W.S. Winston Ho, The Ohio State University

            Novel high-flux reverse osmosis membranes with hydrophilic
additives were synthesized and characterized under brackish water desalination
conditions.  Four selected hydrophilic additives, o-aminobenzoic
acid-triethylamine salt, m-aminobenzoic acid-triethylamine salt,
2-(2-hydroxyethyl) pyridine, and 4-(2-hydroxyethyl) morpholine, were
added into m-phenylenediamine
(MPD) solution to react with trimesoyl
chloride (TMC) during the interfacial polymerization between MPD and
TMC.  The effects of different concentrations for each hydrophilic
additive were evaluated using brackish water desalination
tests with 2000 ppm NaCl solution at 225 psi and 25^oC. 
After the additive concentration was optimized, the synthesized membranes showed
36.7 gallons/ft²/day water flux and
98.2% salt rejection or greater. After the post-treatment using aqueous solutions containing glycerol, sodium lauryl
sulfate, and camphorsulfonic acid-triethylamine salt, the water flux of the
membrane was further increased. The resulting membrane showed a flux of 52.6
gallons/ft²/day and a salt rejection of about 98.8% or
greater.  This membrane outperformed the other membranes evaluated, and it
also exhibited a good stability in terms of water flux (average 50 gallons/ft²/day) and
salt rejection (average 99%) during the entire
period of a 30-day test with 2000 ppm NaCl solution at 225 psi and 25^oC. The good stability was verified by comparing FTIR
spectra of the same membrane sample before and after the 30-day test.