Extraction equilibria of formic and acetic acids from aqueous solution by phosphate-containing extractants

The purpose of this work is to study the feasibility of extraction and recovery of formic acid and acetic acid in the industry synthesis of these two acids. In this work, extraction equilibria of formic and acetic acid with kerosene solutions of such phosphate-containing extractants as trialkylphosphine oxide (TRPO) and tributyl phosphate (TBP) were studied. The solutions of formic and acetic acid in aqueous phase at equilibira ranged from 0.4 mol.L-1 to 8 mol.L-1. The influences of temperature on extraction equilibria were also studied. A model was proposed to describe the equilibria by postulating the structure of the complexes. The parameters in the model were obtained by fitting the experimental data, and the values predicted by this model are very close to the measured results.