Extraction of Carboxylic Acids from Aqueous Solutions by Esters

The extraction of carboxylic acids from their dilute aqueous solutions caused byfermentation processes and industrial waste waters is very important in chemical industry andfrom an environmental protection and economic point of view [1]. Liquid-liquid extraction isapplied as an efficient method for this purpose. Accurate liquid-liquid equilibrium data is neededfor liquid extraction process. The solvent selection is very important in liquid extraction andmany solvents have been tested. The capability of the solvents can be determined by distributioncoefficients and the separation factors calculations. The values greater than 1 for separationfactors indicate that the solvent can be able to extract the solute. Among the organic acids,formic acid is the simplest carboxylic acid with many applications in industry [2]. It has beenfound that the esters are adequate for separation of carboxylic acids from water. In this work, theresults of LLE data for water + formic acid + isobutyl acetate mixture were compared with otherused esters (ethyl acetate and butyl acetate) in the literature [3] for extraction of formic acid fromwater. The sequence of the separation factors for the solvents is: butyl acetate> ethyl acetate> isobutyl acetate.

Keywords:

Carboxylic Acid , Liquid-Liquid Extraction , Ester