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Sketching a Suitable Immobilization Strategy for Ionic Liquid Removal in a Fixed-Bed Bioreactor

Morandeira, Lois, Danho, Madleen, Markiewicz, Marta, Stolte, Stefan, Sanromán, M. Ángeles, Rodríguez, Ana, Deive, Francisco J.
ACS sustainable chemistry & engineering 2019 v.7 no.4 pp. 4307-4314
Halomonas, agar, alginates, biodegradability, bioreactors, cations, choline, diffusivity, hydrogels, ionic liquids, mass transfer, remediation, screening
Generalization of the research on biocompatible ionic liquids is triggering great interest in cholinium-based solvents due to this cation being considered as biocompatible and biodegradable. However, the screening for choline degraders among different microbial sources from different extreme locations revealed the suitability of just one halophilic strain (Halomonas sp. LM1C) to efficiently remove high concentrations of choline cation from aqueous streams. An entrapment-based microbial immobilization technique in hydrogel spheres (agar, alginate, and alginate-polyvinyl) is evaluated in order to ease process scale up. The mass transfer resistance of the selected hydrogels during cholinium chloride (N₁₁₁₂OHCl) diffusion was evaluated by determining the external mass transfer (k) and diffusion coefficients (Dₑ). The results revealed the absence of significant diffusion problems for alginate and alginate-polyvinyl, while the agar-based matrix led to significant cell leakage. Given the superior mechanical performance of alginate-polyvinyl support at flask scale, this was selected to implement the process at a fixed-bed bench-scale bioreactor, leading to complete contaminant remediation.