Parametric Optimization of Lactic Acid Extraction from Aqueous Solution in a Mixed Flow Reactor Using Emulsion Liquid Membrane by Response Surface Methodology

A. Thakur, P. S. Panesar and M. Singh

Abstract
A statistical programme using Box-Behnken design, which applies a response optimization algorithm, was used to calculate and optimize simultaneously the lactic acid extraction by emulsion liquid membrane (ELM) in a mixed flow reactor. A 3-level Box-Behnken design with seven variables i.e. lactic acid concentration, internal reagent concentration, Alamine 336 fraction in oleyl alcohol, stirring speed, fraction of acceptor phase containing internal reagent in emulsion, feed: emulsion ratio and residence time was used to identify a significant correlation between the effect of these variables on lactic acid extraction from aqueous phase since the conventional practice of single factor optimization by maintaining other factors at an unspecified constant level does not depict the combined effect of all the factors involved. The experimental values were found to be in good agreement with predicted values. The analysis of the variance (ANOVA) shows that all the extraction process parameters significantly affect the performance, as well as shows that there are some interactions between the extraction parameters. The contribution of feed: emulsion ratio and stirring speed on extraction efficiency was more than other factors and the fraction of acceptor phase in emulsion has minimum contribution. The optimum value of the process parameters for the maximization of extraction of lactic acid from aqueous phase using ELM in MFR by the application of Box-Behnken design has been found. The recommended optimal conditions have been verified by conducting confirmation experiments. It can be concluded that the Box-Behnken experimental design provides a suitable means of optimizing and testing the robustness of lactic acid extraction in a MFR using emulsion liquid membrane and 100 % lactic acid extraction in MFR using ELM from aqueous feed can be achieved in few minutes within the specified range of independent process parameters.

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Keywords
Emulsion liquid membrane, lactic acid, extraction, mixed flow reactor, response surface methodology