Since the majority of biodiesel is produced using a base-catalyzed
process, we first examined waste glycerol from base-catalyzed processes.
The addition of ChCl (in the range of 5–35 mol%) to waste glycerol
from base-catalyzed biodiesel synthesis did not yield the hoped-for homogeneous
solutions. Instead, dark brown to black solutions that usually
thickened into gelatinous solids resulted. There were several
attempts at changing the composition of the waste glycerol to allow
for the formation of a DES. These attempts included neutralization of
glycerol, acidification of glycerol, addition of known amounts of methanol,
and addition of known amounts of water. None of these modifications
allowed for the formation of a DES using waste glycerol from a
base-catalyzed process. The base-catalyzed glycerol mixtures with
ChCl are still being actively investigated in order to elucidate the underlying
reasons for these observations.