Highly improved organic solvent reverse osmosis (OSRO) membrane for organic liquid mixture separation by simple heat treatment

The development of highly selective organic solvent reverse osmosis (OSRO) membrane for organic liquid separation is in great demand, but remains very challenging owing to the small sizes of organic liquids. We recently reported a polyketone (PK) supported polyamide (PA) membrane as an OSRO membrane, but only with a moderate separation factor of 8.4 for methanol from a methanol/toluene mixture. Herein, a well-controlled two-step heat treatment; first oven heating, followed by hot water heating, was described to remarkably improve the selectivity. Heat treatment efficiently shrunk the PA layer and enhanced its hydrophilicity. Consequently, the separation factor was highly improved to 45.0, outperforming previously described membranes. The effects of crucial operation conditions, including co-solute, applied pressure, feed ratio, feed temperature, and operation time were evaluated. The developed highly selective OSRO membrane and systematical separation process investigation make significant contributions in addressing various organic liquid mixture separations.