How to produce biodiesel easily using a green biocatalytic approach in sponge-like ionic liquids

Hydrophobic ionic liquids (ILs) based on cations with long alkyl side-chains (e. g. N-octadecyl-N',N '',N'''-trimethylammonium bis(trifluoromethylsulfonyl)imide ([C(18)tma][NTf2])) are switchable ionic liquid/solid phases with temperature that behave as sponges. As liquid phases, they are excellent monophasic reaction media for lipase-catalyzed methanolysis of triolein, resulting in fast and efficient biodiesel synthesis, e. g. up to 100% yield in 8 h at 60 degrees C, with exceptional enzyme stability (up to 1370 days half-life time at 60 degrees C). As solid phases, the reaction mixture can easily be fractionated by iterative centrifugations at controlled temperature into three phases, i.e. solid IL, glycerol and pure biodiesel. A straightforward and sustainable approach for producing biodiesel has been developed, allowing full recovery and reuse of the biocatalyst-IL system for successive cycles and suitable for scaling-up.