Gibberellic acid extraction from aqueous solutions and fermentation broths by using emulsion liquid membranes

The extraction of gibberellic acid (GA₃), a powerful vegetal growth promoter widely used in agriculture, has been studied using emulsion liquid membrane (ELM) technology. The system used in this study consisted of a water-in-oil emulsion made of KCl aqueous solution and n-heptane stabilised by the surfactant SPAN 80. Aliquat 336, a commonly used carrier, was added to organic phase in order to increase both mass transfer and selectivity. This emulsion was dispersed on either prepared aqueous solutions of GA₃ or fermentation broths. The fermentation was performed using the fungi Gibberella fujikuroi in fed-batch modality, achieving GA₃ concentrations around 0.65 g L^-1. Selection experiments pointed out that the most important variables in the extraction process were surfactant concentration (SPAN 80), carrier concentration (Aliquat 336), and time extraction. An optimisation experimental protocol was carried out using prepared GA₃ solutions, achieving the maximum extraction (88%) under the following conditions: Aliquat 336 4.3% (v/v); SPAN 80 4.4% (v/v); extraction time 20 s. When the optimisation of these variables was carried out using fermentation broth the optimum conditions found were Aliquat 336 7.4% (v/v); SPAN 80 11.2% (v/v) and extraction time 62 s. Under these conditions, the extraction yield was 68% and the concentration increase was 2.2-fold. These results suggest that GA₃ extraction using ELM is perfectly possible and its application in other configurations and scales, such as pilot scale column configuration should be considered.