2.4. Preparation of DESs
After separating the glycerol from an acid-catalyzed biodiesel synthesis
and removing excess methanol as above, DESs were prepared
by stirring ChCl in crude glycerol at 80 °C for 1 h. Sample volumes of
25.0 mL glycerol were combined with appropriate masses of ChCl to
result in final composition ranging between 5–35 mol% ChCl (for
example, 4.7853 g ChCl was added to 25.0 mL of glycerol from an
acid-catalyzed biodiesel synthesis to prepare a 10% ChCl DES). For
these calculations, the density and molar mass of the waste glycerol
were assumed to be the same as pure glycerol. Since themeasured density
of the glycerol from acid-catalyzed biodiesel is similar to that of
pure glycerol (1.258 g/mL vs 1.261 g/mL; see Table A.1), we believe
that these assumptions introduce a negligible amount of error to these
preparations.