Predicting the Electrochemical Pressure-Driven Membrane Separation of Industrial Solutions Using Friction Theory

An improved approach to determining the kinetic characteristics of electrochemical pressure-driven membrane separation of solutions has been proposed. It is based on the Spiegler friction theory and takes into account the combination of the effects of chemical and electrochemical potentials. The numerical values of the coefficients of friction f(omega m), f(+m), and f(+omega) in the solvent-membrane, solute (cations)-membrane and solute (cations)-solvent systems, respectively, were found using the example of the electrochemical pressure-driven membrane separation of aqueous solutions of CuSO4, Ni(NO3)(2), and Fe(NO3)(3) with concentrations of 1 x 10(-2), 2 x 10(-3), and 1 x 10(-5) mol/L, respectively, using MGA-95 and MGA-100 membranes. Empirical coefficients to determine approximating curves were also determined. It was detected that the absolute values of these coefficients increased with increasing applied electric potential in almost all cases. An exception was mass transfer through the near-cathode membranes in the separation of the Fe(NO3)(3) solution. The absolute values of the coefficients of friction were lowest in the separation of the CuSO4 solution and highest in the separation of the Fe(NO3)(3) solution. The derived approximating dependences of the coefficients of friction on the electric potential were used to solve the inverse problem to find the retention factors and the outlet solvent flux. This can be efficiently used to predict the mass-transfer mechanism and calculate the characteristics of electromembrane units.