The Production of Citric Acid Using Electrodialysis with Bipolar Membrane of Sodium Citrate Solutions
B. Iglinski, S. Koter, R. Buczkowski, M. Lis
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Nicolaus Copernicus University, Department of Chemistry,
Gagarina 7, 87-100 Toruń, Poland
Pol. J. Environ. Stud. 2006;15(3):411–417
Investigations on sodium citrate conversion to citric acid by the pure electrodialysis process with bipolar membrane were carried out. The current efficiencies based on the number of moles of produced acid and on the concentration changes were determined. Both the mean and the instantaneous efficiencies were calculated. It was found that the mean efficiencies of acid and base are higher at the lowest current densities (52 mA/cm2), with the maximum being observed at 78 mA/cm2 for the highest initial salt concentration (1.4 mol/dm3). Higher initial sodium citrate concentration in the salt circuit increases the process efficiency. In the case of low initial salt concentrations, as the process progresses, acid instantaneous efficiency, CEa, decreases with time. For cs = 1 mol/dm3 it is practically constant, and for higher salt concentrations they even grow. In the case of the highest investigated current density (104 mA/cm2), the opposite situation was observed; that is, the CEa decreases with time for the higher salt concentration cs = 1.3 mol/dm3.