Separation of isopropanol from aqueous solution by salting-out extraction

A novel salting-out extraction process has been developed to separate isopr opanol from aqueous solution. Potassium carbonate was experimentally shown to be effective in modifying the liquid-liquid equilibrium (LLE) of an isop ropanol/water/hexane system in favour of the solvent extraction of isopropa nol from an aqueous solution with hexane, particularly at suitable salt con centrations. Potassium carbonate enlarged the area of the two-phase region. This effect essentially increased the distribution coefficient of isopropa nol between hexane and water and increased the separation factor for isopro panol vs water, which is an important consideration in designing a solvent extraction process. The effects of potassium carbonate concentration, tempe rature and pH on the LLE were studied. Finally, a phi 30mm x 1200mm recipro cating plate column (RPC) was tested to separate isopropanol from an aqueou s solution. When isopropanol in an aqueous solution with composition of iso propanol/water=1:0.95 (wt/wt) was extracted by hexane assisted with 30% (wt %) potassium carbonate aqueous solution, the alcohol-water ratio increased to 11:1 in the extract. (C) 2001 Society of Chemical Industry.