Method for purifying an aqueous-alcoholic feedstock comprising ethanol and acetaldehyde

A process for the purification of a hydroalcoholic feedstock (1) comprising at least water, ethanol, acetaldehyde and impurities, said process comprising:

• a) a step of countercurrentwise liquid-liquid extraction, comprising an extraction section comprising an extractor (2) that is fed at the top by said hydroalcoholic feedstock (1) and at least a fraction of an intermediate raffinate resulting from a countercurrentwise liquid-liquid back-extraction step b) and at the bottom by an extraction solvent (3), and that produces at the top an extraction stream (5) and at the bottom a raffinate (4) comprising water, ethanol and acetaldehyde, wherein said extraction section is operated at a mean temperature in the extractor of between 15 and 30° C.;
• and
• b) the step of countercurrentwise liquid-liquid back-extraction comprising a back-extraction section comprising a back-extractor (6) that is distinct from the extractor of step a) and fed at the top by an acidic aqueous solution (7), and at the bottom by the extraction stream (5) resulting from step a), and that produces at the top an extract (8) and at the bottom said intermediate raffinate, wherein said back-extraction section is operated at a mean temperature in the back-extractor that is distinct from the mean temperature in the extractor of step a) of between 4° and 80° C., wherein said acidic aqueous solution (7) comprises a content of acetic acid of less than or equal to 1.5% by weight of acetic acid with respect to the total weight of said acidic aqueous solution.