Continuous predispersed solvent extraction process for the downstream separation of 2,3-butanediol from fermentation broth

• Predispersed solvent extraction using colloidal liquid aphrons for separation of 2,3-butanediol.
• Stable CLAs formation using centrifugal contactor unit is established for the first time.
• Less energy intensive bubble column was used for countercurrent liquid–liquid extraction.
• Mass transfer parameters for BDO extraction are reported for real fermented system.

2,3-Butanediol (BDO) offers the possibility of expanding the list of value-added chemicals produced from the biorefinery platform. However, a major challenge and technical bottleneck for an efficient biological production in a large scale is the separation of BDO from the fermented broth system. The use of colloidal liquid aphrons (CLAs) in pre-dispersed solvent extraction (PDSE) is considered as an emerging technique for the recovery of bio-based compounds. Herein, we describe the application of an environment friendly PDSE system using CLAs for the recovery of (BDO). Continuous mode of countercurrent extraction employing CLAs is demonstrated for the extraction of synthetic as well as fermented BDO in a bubble column apparatus. For the first time, the use of centrifugal contactor (CCS) is established for the formation of stable CLAs. The optimum system parameters required for the CLA formation using CCS method were: 0.25 wt% sodium dodecyl sulfate (SDS) as ionic surfactant, 0.5 wt% Tween 80 as non-ionic surfactant in butanol–water system having a flow ratio of 2 with agitation of 2000 rpm. Compared to the traditional liquid–liquid extraction (LLE) process, PDSE method provided 35–85% increase in mass transfer coefficient and about 30% reduction in overall solvent loading. In the presence of CLAs, the distribution coefficient (Kd) of BDO was found to be similar for all the concentrations of BDO. The results of this work open up the scope of PDSE–CLAs for the downstream processing of other biorefinery products.

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