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Abstract: 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 (1.1–1.5mh−1 bar−1) and molecular cut-off (MWCO) values (400–500Da) 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 4.0V constant applied voltage, pH: 6.1 for 0.05M equi-molar LYS–GLU–GLY mixture), about 4.0kWhkg−1 of AA separated energy consumption, 82% current efficiency and 90% product recovery showed the economic and technical feasibility of EMC for industrial exploitation. [Copyright &y& Elsevier]

[Display omitted] • A parametrized thermodynamic model proposed to predict phase equilibria. • Performance of the MD simulated in a subroutine custom model. • Scaling of salts are predicted during MD operation. • Scaling prediction is validated via experimental results. • Complex interaction among molecular and ionic species are highlighted. Membrane distillation (MD) for water treatment is significantly impaired by the scaling of dissolved minerals. The type and content of minerals generally measured as total dissolved solids (TDS) in hypersaline brines not only reduce the MD flux but also control the scaling behavior on the membrane surface. The scaling-induced pore blockage further reduces water flux and eventually leads to membrane wetting. The scaling problem is even more pronounced in the treatment of produced water (PW) as it contains 3–7 times higher TDS concentrations, compared to seawater. Theoretically, the necessary conditions for a salt to precipitate can be traced from its solubility product constant and activity of the constituents within the solution. Therefore, a comprehensive thermodynamic model is necessary to represent the electrolyte behavior and to predict the precipitation of different salts in a complex solution like PW. We pursued electrolyte Nonrandom Two Liquid Theory (eNRTL), a state-of-the-art electrolyte model, to address the PW fluid phase equilibria. With a fully parameterized eNRTL model, we predicted salt precipitations in two different PW samples and compared the results against the experimental findings. Furthermore, we forecast the precipitation of salts in response to the change in PW concentration and temperature in the MD operation. [ABSTRACT FROM AUTHOR]