(50f) Bipolar Membrane Electrodialysis for Cleaner Production of Amino/Organic Acids

A bipolar membrane (BPM) is a kind of composition membrane that at least consists of a layered ion-exchange structure with a cationic selective layer and an anionic selective layer. Bipolar membrane electrodialysisis considered as the-state-of-art technology for separation and conversion of amino/organic acids. This technology has considerable promise for environmentally friendly production of organic/amino acids which is able to operate without the need for significant chemicalsand energy input. In this study, the production of three amino acids (methylglycine, dimethylglycine and trimethylglycine) with similar structure but different alkyl groups was investigated usingbipolar membranes electrodialysis. Effects of feed concentration, current density and cell configuration on product yield were intensively analyzed in terms of ion dimensions, intrinsic transport velocities, ion concentration, ion orientation, and the interaction between amino acids and membranes.Results indicated that the optimal recovery efficiency was achieved at current density of 20 mA/cm² and feed concentration of 6%. Meanwhile, the optimal energy consumptions and current efficiencies were 2.3kWh/kg and 78% for methylglycine, 2.49 kWh/kg and 69.5% for dimethylglycine, and 3.52kWh/kg and 39.6 % for trimethylglycine, respectively. Additionally, it was found that the product yield ratio for three tested amino acids followed the order: methylglycine>dimethylglycine>trimethylglycine. Naturally, it was clearly shown that the separation and purification of amino acids using bipolar membranes were significantly affected by intrinsic molecular characteristics and molecular volume