| A large amount of highly concentrated phenolic wastewater was generated from coal gasification process,which contains a series of pollutants such as phenol,cresols and polyphenols.Solvent extraction technology combined with biochemical treatment was often applied in the industrial plant to remove phenols from the wastewater.In industrial operation the extraction temperature was increased from 40℃ to 60-80°C in order to decrease clogged by the paraffin components in the heat exchanger before the extraction column.The extraction performance of methyl isopropyl ketone,mesityl oxide,methyl tert-butyl ketone and methyl n-butyl ketone to phenol and cresols from coal gasification wastewater at 60-80°C was studied.The equilibrium behaviors of those systems were also predicted by using COSMO-SAC model.In this work,the liquid-liquid equilibrium data of “ketones(including methyl isopropyl ketone,mesityl oxide,methyl tert-butyl ketone,methyl n-butyl ketone)–phenols(including phenol,o-cresol,m-cresol,p-cresol)-water” ternary systems were measured at 60-80℃.The distribution coefficient and selectivity coefficient calculated by experimental data were used to describe the extracting ability of phenols.The large distribution coefficient and selectivity coefficient showed the good extraction ability of the four extractants to phenols.In the meantime,ketones show the better extraction ability to cresols than to phenol.The order of extraction ability of four ketones to phenols is methyl tert-butyl ketone > mesityl oxide > methyl n-butyl ketone > methyl isopropyl ketone.The NRTL and UNIQUAC models were successfully used to regress the experimental LLE with the RMSD less than 0.025.It is shown that the binary interaction parameters of both models can be used in extraction process simulation.The COSMO-SAC model theory was used to analyze the separation capabilities of ketones for phenols and predict the LLE data of the researched systems.Compared with the σ-profiles of ketones,phenols and water,it can be seen that the interaction between ketones and phenols is much stronger than between phenols and water.It indicated that ketones can easily extract the phenols from the aqueous phase.Meanwhile,the RMSD between the COSMO-SAC predictions and the experimental LLE are all in the range of 0.02 to 0.06. |
