Modelling the electrodialytic recovery of sodium lactate.

The recovery of sodium lactate from model solutions by ED (electrodialysis) was studied using a sequential experimental procedure so as to assess the main engineering parameters (i.e. ion transport numbers in solution and electro-membranes, effective solute and water transport numbers, effective membrane surface area, surface resistances and limiting current intensity) affecting ED stack design and/or optimization. Of the major factors that determine the performance of this ED process, Omega (the current efficiency) was about 88% in the constant-current region, while epsilon (the specific energy consumption) increased from 0.14 to 0.31 kWh x kg(-1) for a solute recovery yield of 95% and j (current density) increasing from 112 to 337 A x m(-2). The specific-resistance values of the anion- or cation-exchange membranes were found to be five or two times greater respectively than those extracted from literature and measured in aqueous NaCl solutions.