Molecular Simulation and Experimental Characterization of Ionic-Liquid- Based Cosolvent Extraction Solvents

SRP Bandlamudi and MJ Cooney and GL Martin and KM Benjamin, INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH, 56, 3040-3048 (2017).

DOI: 10.1021/acs.iecr.6b03931

The use of ionic liquid (IL)/polar covalent molecule (PCM) cosolvent mixtures is a significant new pathway to extract and separate oils and other high-value components from algae and other bio-oil-bearing biomasses. In this work, light-scattering and steady-state fluorescence polarization techniques were utilized to characterize cosolvent behavior at the micro- and macroscales, and their measurements correlated to lipid extraction yields. In addition, molecular dynamics simulations were employed to probe the fundamental interactions between IL and PCMs in solution. Both experimental and computational (radial distribution functions and clustering analysis) data confirmed the increased aggregation between IL cations and anions with increasing methanol concentration. For the 1-ethyl-3-methylimidazolium methyl sulfate/methanol (MeOH) system, this ion aggregation appears to correlate with experimentally observed decreases in the maximum lipid extraction yields for MeOH concentrations above 80 vol %. At these concentrations, MeOH appears to completely surround the aggregates, thereby removing the effect of the IL and diminishing the extraction yield. The successful simulation of experimental observations provides new knowledge on not only the relationship between a molecular-level cosolvent structure and its impact upon the solubility of the extracted material, which in this case are lipids, but also the ability to improve future designs of IL-based cosolvent mixtures for a broad range of extractable materials.

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