Imidazolium ionic liquids-based salting-out extraction of 2,3-butanediol from fermentation broths

Separation of 2,3-Butanediol from Fermentation Broth via Cyclic and Simulated Moving Bed Adsorption Over Nano-MFI Zeolites

The biomass-based platform molecule 2,3-butanediol (2,3-BDO) has a wide range of applications in production of sustainable fuels, chemicals, synthetic rubber, and others. However, the selective separation of 2,3-BDO from multicomponent fermentation broths presents challenges due to its low concentration, high solubility in water, high boiling point, and presence of many other species. Here, we demonstrate remarkably selective enrichment and recovery of 2,3-BDO from a corn stover hydrolysate fermentation broth by a pure-silica nano-MFI-type zeolite adsorbent. By means of cyclic and simulated moving bed adsorption processes, we obtained concentrated aqueous 2,3-BDO streams from the fermentation process stream with ∼93% purity and 3-fold enrichment, and >98% purity and 8-fold enrichment, respectively. These findings provide strong support for large-scale adsorptive separation for biobased 2,3-BDO production.

Recovery of 2,3-Butanediol from Fermentation Broth by Zeolitic Imidazolate Frameworks

The efficient separation of the 2,3-butanediol (2,3-BDO) intermediate from fermentation broth is an important issue in the production of biofuels from biomass-derived intermediates. Two zeolitic imidazolate frameworks ZIF-8 and ZIF-71 were investigated for the adsorption of 2,3-butanediol (2,3-BDO) from fermentation broth via liquid breakthrough adsorption measurements. While both ZIF materials initially show high separation performance, ZIF-71 retains robust separation performance even after aging in ethanol for two years, whereas the capacity of ZIF-8 decreases significantly. The robustness and stability of ZIF-71 are further confirmed with cyclic fixed bed adsorption measurements. The uptake of 2,3-BDO on ZIF-71 reaches >100 g/kg with negligible uptakes of sugars, organic acids, and other alcohols present in the fermentation broth. Excellent selectivity toward 2,3-BDO over water is also achieved. The 2,3-BDO-loaded ZIF-71 can be regenerated efficiently with ethanol as desorbent. These findings indicate that ZIF-71 shows considerable promise as an adsorbent to recover and purify diols from fermentation broths.

Recent Developments in Solvent-Based Fluid Separations

The most important developments in solvent-based fluid separations, separations involving at least one fluid phase, are reviewed. After a brief introduction and discussion on general solvent trends observed in all fields of application, several specific fields are discussed. Important solvent trends include replacement of traditional molecular solvents by ionic liquids and deep eutectic solvents and, more recently, increasing discussion around bio-based solvents in some application fields. Furthermore, stimuli-responsive systems are discussed; the most significant developments in this field are seen for CO₂-switchable and redox-responsive solvents. Discussed fields of application include hydrocarbons separations, carbon capture, biorefineries, and metals separations. For all but the hydrocarbons separations, newly reported electrochemically mediated separations seem to offer exciting new windows of opportunities.