hexane was selected as the solvent for the model oil. First, 80.10 g of phenol,
40.26 g of o-cresol, 40.28 g of p-cresol, and 40.03 g of m-cresol
were added to 500 mL of hexane at 303.15 K in a beaker with continuous
shaking. The solution was then transferred to a 1000 mL
volumetric flask after the phenol and cresols completely dissolved.
Hexane was added to the scale mark of the flask. The model oil was
prepared as mentioned above. The m-cresol model oil with a concentration
of 200.0 g/L was prepared in the same way.
The experiments were performed as follows (Fig. 1): a certain
amount of model oil was placed in a conical flask, and then the
extraction agent with a certain mole ratio to the phenols was
added into the model oil. The flask was placed in an incubator shaker
with a temperature controller within ±0.1 K of an appropriate
temperature and 400 rpm for a known time. After the reaction,
DES was formed, and two layers appeared in the model oil. The system
was allowed to stand for more than 30 min. Finally, the upper
and lower layers were carefully separated by using a funnel