Electrochemical pH-T-Swing Separation of Itaconic Acid for Zero Salt Waste Downstream Processing

Abstract

Biotechnological production of platform chemicals such as (di)carboxylic acids poses economic and environmental challenges in downstream processing. With conventional downstream processes, waste salts are produced in more than equimolar amounts with the product. Therefore, lean waste-free downstream processes are needed to compete with petrochemical products. This work presents a joint development of a biobased production route for itaconic acid featuring low pH value fermentation, reactive extraction, and electrochemical product recovery. By the implementation of an electrochemical pH-T-swing separation process, biobased itaconic acid with a purity of more than 99% was recovered in the crystalline form from the fermentation broth. Based on the measured liquid-liquid and solid-liquid equilibrium, a feasible overall yield of >90% for itaconic acid recovery was calculated for the proposed downstream process. An electrochemical protonation efficiency of 96.2% was determined when the pH-shift electrolysis operates within the buffer range of the itaconic acid. The proposed process eliminates the salt waste from pH-adjusting steps and can perspectively operate with electricity costs being lower than costs for sulfuric acid and sodium hydroxide elsewise required for the pH-swing steps.