As biodiesel production increases worldwide, so does the generation of its glycerol waste byproduct. Purifying
thewaste glycerol is difficult and energy intensive; itwould be preferable to find a productive use forwaste glycerol
requiring little to no refining. Herein, we examine the use of waste glycerol from biodiesel production as a
component in deep eutectic solvents (DESs). Specifically, we examine mixtures of waste glycerol and choline
chloride (ChCl) as prototype simple and inexpensive DESs. The densities and viscosities of thewaste glycerol derived
DESs are consistent with those measured in DESs prepared with clean glycerol. DESs from waste glycerol
are competent solvents for a classical Fisher esterification reaction and show utility in extracting methanol
from crude biodiesel mixtures. These DESs therefore show promise as solvent systems, leading to a decrease in
waste from the ever-increasing production of biodiesel and also serving as a value-added product for biodiesel
manufacturers.