Dehydration of alcohols by pervaporation using hydrophilic polyether urethane membranes

This study presents pervaporation separation of methanol-water (MW), ethanol-water (EW) and isopropanol-water (IW) mixtures through a series of polyethylene glycol (PEG) based polyether urethane membranes. Five polyether urethane (PUPEG) membranes were developed by using PEGs of increasing molecular weight (PEG(200), PEG(400), PEG(600), PEG(1000) and PEG(4000)). PUPEG membranes showed selectivity towards water, which increased with increasing molecular weight as well as increasing polymer chain length of the membrane. PUPEG membrane prepared using PEG(4000) showed highest separation performance in dehydrating water from three alcohol-water mixtures. A pervaporation flux of 0.48 kg/m(2).h was achieved with 94.5% water in permeates from 20% water present in isopropanol-water mixture using PUPEG(4000) membrane. All PUPEG membranes showed water separation performances; flux and separation factor for water varied in the order: MW <EW<IW mixtures.