The Promotion Effect of Ionic Liquids on Polymer-Driven Recovered Water by Microwave Treatment

In view of the difficulties in breaking emulsions and removing oil from polymer-produced water, this study systematically analyzes the promotion effect of anion type, cation type, and concentration of ionic liquid on polymer-driven water produced by microwave treatment. First, when the microwave power is 400 W and the radiation time is 40 seconds, the oil removal rate is only 34.95%. Second, when the anion of the ionic liquid is Br−, the oil/water interfacial tension (IFT) reaches the lowest value. During microwave radiation, the ionic liquid adsorbed on the oil/water interface converts more electromagnetic energy to heat energy owing to dipole polarization and interfacial polarization. In addition, bromine salts have the lowest absolute zeta potential; thus, the electroneutralization effect is the largest. Third, as the length of the cationic alkyl chain of the ionic liquid increases, its synergistic effect with the microwaves first decreases and then increases. Finally, during microwave irradiation, as the concentration of 1-hexadecyl-3-methylimidazole bromide salt increases, the oil removal rate first increases rapidly and then decreases slightly. When the concentration of 1-hexadecyl-3-methylimidazole bromide is 1 mmol/L, the oil removal rate reaches the highest value of 90.31%.