Direct transesterification of biomass using an ionic liquid co-solvent system

Abstract

The ability of an ionic liquid–alcohol co-solvent to facilitate the acid-catalyzed (HCl) direct transesterification of intercellular lipids to fatty acid methyl esters (FAMEs) was investigated. The FAME product, which autopartitions to a separate immiscible phase, was easily recovered. With the exception of theChlorella microalgae, the conversion from triglycerides to FAMEs was nearly complete (100%) for all biomass sources investigated and the gravimetric yields of FAME product were found to be similar to those in the absence of acid catalyst. As the co-solvent system used in this study was highly polar, and thus immiscible with the FAME product, the action of the ionic liquid molecules was presumed to provide both hydrophobic regions or channels that provided some association with the alkyl side chains on the lipid, as well as energy to push the FAME product out of phase with the co-solvent, and into its own separate and immiscible phase self, as the ionic liquid anions and cations continued to self associate.

Acknowledgements

The authors would like to thank Goro Uehara for the donation of oil seed samples and Jim DeMattia for the various photosynthetically grown microalgal samples. The authors would also like to thank Wes Yoshida for his help with the NMR analysis.

Financial & competing interests disclosure

This work was supported by funding from LiveFuels and BioEcoTek Hawaii. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

No writing assistance was utilized in the production of this manuscript.