Experimental determination of the liquid-liquid equilibrium system provides basic data for accurate simulation

design and process development of solvent extraction and recovery. In this work

methyl isopropyl ketone (MIPK) was chosen as the extraction agent and the liquid-liquid equilibrium of methyl isopropyl ketone-phenol-hydroquinone-water was studied since phenol and hydroquinone are typical monophenols and polyphenols in the coal chemical industry wastewater. The liquid-liquid equilibrium data were determined at 40℃ under atmospherics pressure. The experimental data were correlated with the NRTL and UNIQUAC models. The binary interaction parameters of the quaternary systems were obtained. The LLE results calculated by the NRTL and UNIQUAC models agreed quite well with the experimental data with root mean square deviations below 0.190% and 0.266% for these two models. Furthermore

the extraction process was simulated with binary interaction parameters calculated from the UNIQUAC model. According to these simulations

the total phenols and total polyphenols in the phenolic wastewater could respectively decrease from 12700 mg×L-1 to 300 mg×L-1 and from 4250 mg×L-1 to 299 mg×L-1 under the operation condition of extraction temperature 40℃

extraction stages 5 and solvent to wastewater ratio 1:7.72.