The extraction efficiency was first investigated by extraction of
lactic acid from its aqueous solution. The effect of extraction time
was investigated by mixing the solvent phase (RCS=10/90) with
the lactic acid aqueous solution and stirring for a period of 30-120
min under room temperature. Fig. 1 shows that with different RSF
(1/4, 1/2, 1/1 and 2/1), there was no obvious increase of extraction
efficiency after 60min, so 60 min was selected in the following experiments.