Models Correlation And Liquid-liquid Equilibrium Of Solvent Extraction Of Diphenols From Coal Chemical Industry Wastewater Containing High Concentration Phenols By Ketones

The dry distillation and gasification processes on inferior coal are usually carried out at the temperature range of 400¹000?.These processes produce a large amount of coal chemical wastewater with highly concentrated phenol and ammonia.The lower temperature of the processes such as coal grading or semi-coking production process will produce wastewater which contain higher concentration of polyphenols.The wastewater is usually treated by the phenol and ammonia recovery technology,and solvent extraction is a key process to recover phenols.So research on the solvent extraction of polyphenols is particularly important.In this work,three kinds of dihydric phenols including catechol,resorcinol and hydroquinone were as the representatives of polyphenols.Through the preliminary analysis of the physical and chemical properties of various extractants and the extraction results from the literature of various extractants compared,four kinds of ketones such as MIPK,MPK,MTBK and MBK were selected as extractants.When extraction temperature is lower than 333.15K in industrial applications,the paraffin components in coal chemical wastewater will bond with fly ash.It results in a serious blockage in the circulating water cooler before the extraction column and the cooler need be cleaned every month.If extraction temperature increased to?333.15³53.15?K,the current situation of fouling would be greatly relieved and cleaning cycle of the cooler could be extended to more than 12 months.Therefore,the liquid-liquid phase equilibrium data of?MIPK,MPK,MTBK,MBK?+?catechol,resorcinol,hydroquinone?+water ternary systems in this work were measured between?333.15³53.15?K.The liquid-liquid phase equilibrium data were also tested using the Hand and Bachman equations.The results showed good linearity and the correlation coefficients R² are greater than 0.99.The values of root mean square error?RMSE?between the calculated and experimental data using the NRTL and UNIQUAC activity coefficient models at different temperatures were all less than 1%.It indicated that both models have high precision and can predict the experimental data very accurately.The obtained binary interaction parameters can be introduced into the simulation software for accurately simulating the extraction of dihydric phenols from coal chemical wastewater containing highly concentrated phenols.Compared the corresponding partition coefficients and selectivity coefficients at298.15K³53.15K,the partition coefficients and selectivity coefficients all showed a decreasing trend with the increasing of temperature or the increasing of dihydric phenols concentration in the aqueous phase.The extraction performances of dihydric phenols by four ketone extractants are as follows:catechol>resorcinol>hydroquinone.At the optimized condition,it can decrease the dihydric phenols concentration from3110 mg·L^-11 in the original wastewater to 300 mg·L^-1 after one extraction process,and this result satisfies with the needs of industrial operation.