Bipolar Membrane Electrodialysis for Direct Conversion of L-Ornithine Monohydrochloride to L-Ornithine

Abstract

In this study, bipolar membrane electrodialysis was proposed to directly convert L-ornithine monohydrochloride to L-ornithine. The stack configuration was optimized in the BP-A (BP, bipolar membrane; A, anion exchange membrane) configuration with the Cl− ion migration through the anion exchange membrane rather than the BP-A-C (C, cation exchange membrane) and the BP-C configurations with the L-ornithine+ ion migration through the cation exchange membrane. Both the conversion ratio and current efficiency follow BP-A > BP-A-C > BP-C, and the energy consumption follows BP-A < BP-A-C < BP-C. Additionally, the voltage drop across the membrane stack (two repeating units) and the feed concentration were optimized as 7.5 V and 0.50 mol/L, respectively, due to the low value of the sum of H+ ions leakage (from the acid compartment to the base compartment) and OH− ions migration (from the base compartment to the acid compartment) through the anion exchange membrane. As a result, high conversion ratio (96.1%), high current efficiency (95.5%) and low energy consumption (0.31 kWh/kg L-ornithine) can be achieved. Therefore, bipolar membrane electrodialysis is an efficient, low energy consumption and environmentally friendly method to directly convert L-ornithine monohydrochloride to L-ornithine.

Tyrosine Amino Acid as a Foulant for the Heterogeneous Anion Exchange Membrane

“…The production of amino acids grows up rapidly and requires efficient procedures for their recovery from mixtures, purification, and concentration. The reagentless, environmentally and economically feasible method of electrodialysis with ion exchange membranes is applied to the purification of amino acids from inorganic impurities (such as mineral salts) [1][2][3][4][5][6][7], separation of amino acids and carbohydrates [5,8], separation of amino acid mixtures [9][10][11], conversion of amino acid hydrochlorides into amino acids [12][13][14], and concentration of amino acid solutions [15,16].…”