Comparative study on tartaric acid production by two-chamber and three-chamber electro-electrodialysis

Abstract

Acidification is an essential step in organic acid production. In this work, an environmentally friendly electro-electrodialysis (EED) process was carried out to transform potassium tartrate (K2Tar) to tartaric acid (H2Tar) without additional waste salt generation. The characteristics of ions migration in the two-chamber EED and three-chamber EED processes were investigated, and the conversion ratio of tartaric acid and specific energy consumption of the two configurations were also compared. The competitive migration of K+ ions and H+ ions through cation exchange membrane was the key factor affecting the extent of acidification in the two-chamber EED process, while the selective transport of tartrate ions (Tar2−) and H+ ions through the anion exchange membrane influenced the three-chamber EED process significantly. The three-chamber process generated pure H2Tar solution with higher concentration than the two-chamber process and reached a conversion ratio of 99% after 120 min’s operation running at 7 mA/cm2. Owing to the lower resistance of the two-chamber membrane stack, the specific energy consumption in the two-chamber EED process was lower than that of three-chamber EED process. This work provides important knowledge for assessing the application of EED in the production of tartaric acid (H2Tar) from potassium tartrate (K2Tar) and a better understanding of the transport phenomena in the system with ionic organic compounds.