Direct conversion of monopotassium L-aspartate by electrodialysis metathesis: Stack resistance, co-ion transport, and concentration polarization

Abstract

The conventional method of synthesizing high-value amino salt from amino acid ammonium involves several steps including acidification, precipitation, and separation. This process not only consumes acids and bases but also generates a substantial amount of wastewater. In this study, monoammonium L-aspartate was directly converted to monopotassium L-aspartate (Asp-K) using electrodialysis metathesis (EDM). To achieve this, K2SO4 was chosen as the optimum potassium salt to supply K+ due to its relatively lower co-transport rate with SO42− ions and lower stack resistance. Additionally, the membrane type was optimized as CIS/AIS membranes due to their low stack resistance, high ion permeability for the transport of Asp− ions, and low concentration polarization. The process resulted in high-purity Asp-K (99.8 %) and low energy consumption (0.14 kWh/kg Asp-K). These results indicate that the EDM process is a promising method for converting amino salts with high purity.