Phase transition extraction using solvent mixtures with critical point of miscibility

A novel separation process, phase transition extraction, proposed in this article uses solvents that have a critical point of miscibility with the feed liquid to be extracted. Alternate heating and cooling across the coexistence curve leads alternatively to a homogeneous phase or two separate phases. The formation of a homogeneous phase in the mixing stage eliminates the need for intense agitation. Coalescence on cooling in the settling stage is rapid in the presence of impurities that in conventional extraction lead to emulsions. A fermentation broth is extracted without a centrifuge with improved recovery of the antibiotic extracted. The process may have a significant advantage for cases in which extraction is difficult either due to formation of stable emulsions and dispersions or shear sensitivity.