Ethanol/methanol extraction, petroleum ether/ acetic ether extraction, and benzene/ethanol extraction were carried out at temperature of 75[degrees]C, 90[degrees]C and 95[degrees]C, respectively.
petroleum ether/acetic ether' !benzene/ ethanol), PA-BE-EM (petroleum ether/ acetic ether '!
Acetic ether was added into NaAl[O.sub.2] solution in different concentrations with 2:1 molar ratio of
acetic ether and NaAl[O.sub.2], respectively.
Benzene, methanol, petroleum ether (60-90[degrees]C),
acetic ether and ethanol (chromatographic grade) were prepared for the subsequent experiments.