This work investigates the competitive transport of acetic and citric acids from model solutions containing both salt and molecular forms of the acids. The study examines two membrane systems: a Ralex AMH heterogeneous membrane with a total concentration of 0.1 mol-eq/L of each acid and a Ralex AMH/MF-4SK bilayer membrane with a total concentration of 0.5 mol-eq/L of each acid. Experiments were conducted at solution pH values of 1.0, 4.8, and 9.0. The separation of organic acids by electromembrane processes is a key challenge when these acids are obtained from mixtures. The results show that electrodialysis extraction of citric acid from solution containing 0.1 mol-eq/L of organic acid ions and molecules, using Ralex AMH membrane at current density of about 3 A/dm2 and pH 9.0, yields a specific selective permeability coefficient PCit/Ac equal to 4 for citric acid compared to acetic acid. Electrodialysis removal of acetic acid from solution containing 0.5 mol-eq/L of organic acid ions and molecules using the Ralex AMH/MF-4SK membrane at current density of 0.17 A/dm2 and pH 9.0 results in PCit/Ac value of 0.025.
Карпенко et al. (Sun,) studied this question.