Functionalized chitosan based nano-filter membranes for pH-controlled separation of amino acids

PH-controlled separation of AAs was achieved by electro-membrane cell (EMC) with three compartments (central, comp. 1 and comp. 2). EMC is based on the principles of electrodialysis (ED) using indigenous cation-exchange and anion-exchange nanofilter (C-NF and A-NF, respectively). Water permeabilities (1.1-1.5 mh^-1 bar^-1) and molecular cut-off (MWCO) values (400-500 Da) for C-NF and A-NF, were suggested their nanofilter (NF) nature. Electrochemical properties of these membranes confirmed their suitability for EMC. Chronopotentiometric studies revealed the electro-transport of positively charged lysine (LYS⁺) and negatively charged glutamic acid (GLU ^-) across C-NF and A-NF, respectively, at pH: 6.1 under applied voltage. While glycine at its pI (pH: 6.1) remained immobile. Thus, separation of AAs (ternary mixture) by iso-electric point (pI) focusing of one component was proposed. Under optimized experimental conditions (i.e. at 4.0 V constant applied voltage, pH: 6.1 for 0.05 M equi-molar LYS-GLU-GLY mixture), about 4.0 kW h kg^-1 of AA separated energy consumption, 82% current efficiency and 90% product recovery showed the economic and technical feasibility of EMC for industrial exploitation.