The effect of the concentration of lactic acid in aqueous solution
on extraction efficiency was obtained by adding different concentration of lactic acid into aqueous solution and stirring with solvent
phase (RCS=30/70, RSF=1/2) under room temperature for 60 min.
The extraction efficiency decreased to 60% with the concentration
of lactic acid increasing from 5 g L−1 to 100 g L−1 (Fig. 4).