Nanofiltration of glucose and sodium lactate solutions: Variations of retention between single- and mixed-solute solutions

Antoine Bouchoux (1) , Hélène Roux De-Balmann (1) , Florence Lutin (2)

1 LGC - Laboratoire de Génie Chimique
2 Eurodia industrie

The aim of this work was to investigate NF as a purification step, i.e. sugar removal, in the production process of lactic acid from sodium lactate fermentation broth. Experiments were carried out with the Desal 5 DK membrane and solutions of increasing complexity, i.e. single-solute solution of sodium lactate and glucose and mixed-solute solutions containing both solutes. Concentrations close to those found in a fermentation broth were chosen. Experimental results were used to get the variations of the intrinsic retention versus the filtration flux in order to achieve comparisons without interference of concentration polarization. Quite distinct retentions were obtained for glucose and sodium lactate in single-solute solutions, so that the purification was expected to be feasible. However, it was pointed out that glucose retention is significantly lower in mixed-solute solutions, i.e. as far as lactate is present. This decrease is such that retentions of both solutes become comparable so that any purification is unachievable. Experiments at different salt concentrations and with a salt of different nature (mineral salt-NaCl) were also performed. Again, it was found that the presence of NaCl tends to decrease glucose retention. Moreover, the phenomenon is shown to be related to salt concentration in both cases, i.e. with sodium lactate and NaCl. Some 1 possible explanations of this effect are provided in this paper. Further investigations are still in progress to improve the knowledge of the involved mechanisms.

Mots clés: Intrinsic retention; Lactic acid; Nanofiltration; Salt and sugar retention; Hydration

Domaines: Génie chimique; Génie des procédés

Antoine Bouchoux, Hélène Roux De-Balmann, Florence Lutin. Nanofiltration of glucose and sodium lactate solutions: Variations of retention between single- and mixed-solute solutions. Journal of Membrane Science, 2005, 258 (1-2), pp.123-132. ⟨10.1016/j.memsci.2005.03.002⟩. ⟨hal-01883123⟩