Forward osmosis using draw solutions manifesting liquid-liquid phase separation

Desalination via forward osmosis using draw agents whose regeneration is aided via liquid-liquid phase separation has gained much attention in recent years. In the present study, mixtures of two different glycol ethers, tripropylene glycol methyl ether and tripropylene glycol n-butyl ether, have been studied as potential draw agents. Water activity, viscosity and diffusion coefficient of draw solutions have been measured at different mixture compositions, concentrations and temperatures. Osmotic pressures of these draw solutions decreases strongly with increasing temperature. Forward osmosis experiments performed with these draw solutions reveal appreciable initial loss of trans-membrane water flux, reverse solute flux and severe concentration polarization.