New polymeric materials for reverse osmosis membranes

The results obtained from investigations on new aromatic polyamides containing carboxylic groups suitable for reverse osmosis are reported. The polymers are fabricated into asymmetric membranes by the Loeb-Sourirajan technique. The effects of fabrication conditions were also investigated to yield the optimum membranes for brackish water and sea water desalination, respectively. Performance characteristics of the membranes are 0.30 m³/m²·day above 98% rejection at 70 kg/cm²-35000 ppm NaCl, and 1.0–1.15 m³/m²· day, 97–98% rejection at 40 kg/cm²-5000 ppm NaCl. They exhibited good resistance in the tests carried out in alkaline medium (pH 10) and acid medium (pH 4).