Separation of isopropanol from aqueous solution by salting‐out extraction

Abstract

A novel salting-out extraction process has been developed to separate isopropanol from aqueous solution. Potassium carbonate was experimentally shown to be effective in modifying the liquid±liquid equilibrium (LLE) of an isopropanol/water/hexane system in favour of the solvent extraction of isopropanol from an aqueous solution with hexane, particularly at suitable salt concentrations. Potassium carbonate enlarged the area of the two-phase region. This effect essentially increased the distribution coef®cient of isopropanol between hexane and water and increased the separation factor for isopropanol vs water, which is an important consideration in designing a solvent extraction process. The effects of potassium carbonate concentration, temperature and pH on the LLE were studied. Finally, a f30 mm  1200 mm reciprocating plate column (RPC) was tested to separate isopropanol from an aqueous solution. When isopropanol in an aqueous solution with composition of isopropanol/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.

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