Extraction of monocarboxylic acids by trioctylmethylammonium di(2-ethylhexyl)phosphate

Abstract

The laws of the interphase distribution of saturated monocarboxylic acids in the system with the binary extracanttrioctylmethylammonium di(2-ethylhexyl)phosphate were studied. The extraction isoherms of monocarboxylic acids by 0.2 M solution of trioctylmethylammonium di(2-ethylhexyl)phosphate in toluene were obtained, and it was shown that they are rectilinear. The extractibility of acids decreases in the following order: butyric > propionic > formic> acetic> lactic, which corresponds to the anion-exchange order for the initial salts of quaternary ammonium bases. The mechanisms of the distribution of monocarboxylic acids were proposed. The study of the extraction of acetic and propionic acids as a function of the acidity of the aqueous phase revealed that the acids are extracted most efficiently from acid solutions. A decrease in the distribution coefficients with an increasing pH of the aqueous phase is observed, which indicates the possibility of efficient reextraction of monocarboxylic acids from organic solutions.