The Effect of Additives and Impurities on the Partition of Ethanol into n‐Decanol from Aqueous Solutions

Abstract

AbstractThe recovery of biological products from fermentation media by direct liquid‐liquid extraction is complicated by the presence of impurities. These may comprise either side products of the bio‐transformation or residual species from the pre‐fermentation substrates. As a corollary to the detrimental effect of impurities upon extraction, addition of reagents, for example salts, can be used to enhance the extraction and mitigate to some extent against these. This paper describes an experimental study of the partitioning of ethanol from aqueous solutions into 1–decanol. Specific groups of impurities and additives were identified, comprsing: electrolyte compounds (including acids, bases, and salts), ionic and non‐ionic surfactants, commercial de‐emulsifiers, organic acids, polysaccharide compounds (i.e. sugars and starch), protein, biomass (including yeast and bacteria), and 1–propanol. A number of thermodynamic models for predicting the effect of each additive on the phase distribution behaviour of ethanol were screened and tested. The additives considered in this paper are confined to those of relatively simple chemical structure and included 1–propanol, oleic acid, glucose, sodium chloride, sodium hydroxide, calcium chloride, ammonium chloride, ammonium sulphate, and hydrochloric acid. These were added in controlled amounts to the principal extraction system components and the effect upon the partition coefficients of ethanol determined.