| Synthesis of hydrophobic imidazolium ionic liquids and treatment performance of oilfield wastewater were studied, and the corresponding process parameters were optimized. Three kinds of hydrophobic imidazolium ionic liquids:[bmim]PF6, [hmim]PF6 and [omim]PF6 were synthesized, and their structure and physical/chemical properties were characterized. Extraction time, pH value of wastewater and temperature of wastewater were studied in detail, which were the main factors on the treatment of simulation of phenolic wastewater. The result indicated that extraction equilibrium can be reached within 20 minutes. The extraction rate of m-cresol,p-cresol and o-cresol were 76.8%,79.53% and 84.52%. The partition coefficient of phenol decreased when the pH value and the temperature increased.The extraction of oilfield wastewater with [omim]PF6 was studied. Extraction time, pH value of wastewater and extraction ratio were studied, which were the main factors on the treatment of wastewater. The result indicated that the best condition was obtained when the extraction time was 60min, pH was 2-3, and the volume ratio between oilfield wastewater and ionic liquid was 5:1. The effect of oilfield wastewater treatment with renewable ionic liquids was discussed. The effect of sewage treatment was still very good, when ionic liquid was used circularly for 6 times. Transmittance, removal efficiency of CODcr and oil only reduced by 0.9%,1.3% and 1.5%. This showed that the ionic liquids could be reused. UV spectra showed that there were no other substances generated in the wasterwater treatment process.
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