For Fraction I, the recovery rates of methanol and ethanol in the aqueous phase and the alkanes in the oil phase were over 95%. Only a trace amount of alkanes was detected in the aqueous phase, indicating that water has a high selectivity for alcohols. Since the recovery rate of butanol is only 56.7%, perhaps a more polar extractant is needed.
For Fraction II, except for hexanol, high recovery rates were obtained for all of the alcohols in the aqueous phase, and the hydrocarbons and alcohols were well separated. A similar situation occurred for Fraction III when CH3CN–H2O was used to extract the alcohols. The primary alcohols accounted for about 10% of the aqueous phase and the average recovery of alcohols was 84.94%.
Compared with Fraction II, the extractant had a poorer ability to extract alcohols from Fraction III, lowering the recovery rate of the primary alcohols and increasing the amount of saturated alkanes in the extract phase.
For Fraction IV, none of the primary alcohol recovery rates exceeded 90% and the recovery rate of octadecanol was only 43.66%. As the number of carbon atoms increases, the difficulty in separation of alcohols and hydrocarbons increases because the polarities of the alcohols and alkanes are more similar. Fortunately, the alcohols remaining in the hydrocarbons can be also burned as fuels.