Bipolar membrane electrodialysis for cleaner production ofN-methylatedglycine derivative amino acids

摘要

In this study, cleaner production ofN-methylglycine (NMG),N,N-dimethylglycine (DMG), andN,N,N-trimethylglycine (TMG) with similar structures but different methylate groups was performed using bipolar membrane electrodialysis (BMED). The effects of the feed mass concentration and current density on the separation performance were intensively analysed in terms of the molecular size, molecular structure, ion concentration, and interaction between amino acids and membranes. The results indicated that the optimal recovery performance was achieved at a current density of 200 A/m(2)and feed mass concentration of 6%. Under the optimal conditions, the energy consumption and current efficiencies were 2.3 kWh/kg and 78% for NMG, 2.49 kWh/kg and 69.5% for DMG, and 3.52 kWh/kg and 39.6% for TMG, respectively. It was speculated a competition for water splitting occurs between the bipolar membranes and anion exchange membranes when BMED is used for the separation and purification of large-sized bioproducts.