The Phase Equilibria Study And Process Simulation Of Extracting Phenols And Carboxylic Acids From Highly Concentrated Wastewaters In Coal Chemical Industry With Ketones As The Extractant

A large amount of phenol-containing wastewater is produced from a wide range of industries, especially coal chemical industry. In industry, the combination of phenol-ammonia recovery and biochemical treatment was proven to be an efficient method to treat such wastewater. In this thesis, we analyzed coal chemical industrial wastewater carefully with GC-MS, considered the physical properties and extraction performance of various extraction agents, and then studied methyl tert-butyl ketone as an extraction agent.Liquid-liquid equilibrium(LLE) data are the basis of solvent extraction study. The extractions of several phenols were investigated in this work, which were taken as a simplified model of a typical coal chemical industrial wastewater. Liquid-liquid equilibrium data of several LLE systems: MTBK- phenol- water, MTBK-(o-,m-,p-) cresol- water, MTBK- 1,2-benzenediol- water, MTBK- phenol- 1,2-benzenediol- water, MTBK- acetic acid- water, MTBK- propionic acid- water and MTBK- butyric acid- water at different temperatures were measured. The reliability of experimental tie-line data was verified by the Hand, Bachman or Othmer-Tobias equations. The experimental data were correlated with the NRTL and UNIQUAC models to yield binary interaction parameters for relevant process simulations. According to the root mean square deviation(RMSD) between experimental data and calculated results, both these two models correlated the experimental LLE data successfully.The binary interaction parameters calculated from the NRTL or UNIQUAC models were used to simulate the process of extracting phenols. We studied the relationship between the concentration of phenol, 1, 2-benzenediol, total phenols and extraction stages or phase ratio. The result shows that, the concentration of total phenols can be reduced to 300 ppm from 13000 ppm, which met with the requirement of the subsequent biochemical treatment. In order to get the optimal operation conditions of the extraction tower, total phenol concentration of 300 ppm was set as the goal for the extraction. The results showed that, when the flow of extraction agent and that of wastewater flow ratio R = 12.223:100, the extracting agent usage is minimum, which lead to the max economic efficiency.