Liquid-liquid Equilibrium Research And Process Simulation On Extraction Of Phenols From Coal Chemical Wastewater Containing High Concentration Phenols By 2-Octanone/1-Dodecanol

How to effectively treat highly concentrated phenol-containing wastewater from coal chemical industry is a tough problem in wastewater treatment.Phenols,cresols,dihydric phenols and other phenolic compounds which are common highly toxic organic compounds exist in this type of wastewater.The combination approach of solvent extraction and biochemical method is a main way to treat highly concentrated phenol-containing wastewater in coal chemical industries.Presently the common extraction agents are methyl isobutyl ketone and diisopropyl ether,etc.and they have high solubility in water.Usually the residual solvent in the raffinate phase needs to be stripped,and the recovery energy consumption is relatively large.In this study,2-octanone and 1-dodecanol with low solubility in water were screened to carry out liquid-liquid equilibrium and extraction simulation of phenols from wastewater.In this work,liquid-liquid equilibrium data of solvent?2-octanone or 1-dodecanol?-phenols-water at different temperatures were measured by equilibrium kettle method.Hand,Othmer-Tobias or Bachman equations were used to test the reliability of liquid-liquid equilibrium data.All correlation coefficients R² were greater than 99%,which demonstrated the reliability of experimental data.Distribution coefficient?D?and separation factor?S?were used to evaluate the extraction performance of the solvent.Among seven phenolic compounds,cresols were the most easily extracted and?m-,p-?-hydroxyphenol were the most difficult to be extracted at the same temperature.Both 2-octanone and 1-dodecanol have good extraction efficiency on phenolic compounds.2-octanone has more excellent extraction performance than1-dodecanol,and its D on p-hydroxyphenol reached up to 70.12.The NRTL and UNIQUAC activity coefficient models were used to correlate experimental data,and the binary interaction parameters of the corresponding system at different temperatures were obtained by regression.The root mean square deviations?RMSDs?between predicted phase equilibrium data and experimental data were calculated.And they were used to explain whether these activity coefficient models are suitable for describing the phase behavior.The RMSD values of all systems are within 1.44%,which show that both models are suitable to correlate the studied systems.Under the same conditions,D of different solvent on the extremely diluted phenol-containing aqueous solution(1g·L^-1)was determined and calculated.The enthalpy change in the extraction process was estimated by combining extraction equilibrium theory with van't Hoff equation.It was found that the extraction process was exothermic reaction and high temperature was not beneficial to the extraction.The binary interaction parameters obtained from the quaternary system?extractant+phenol+resorcinol+water?data were used to simulate the extraction unit,and the operating parameters of the extraction process were optimized.This research tested feasibility of industrial applications of 2-octanone and 1-dodecanol to treat phenolic wastewater,and it also provided important experimental support and theoretical basis for recovery and separation of phenols from coal chemical wastewater containing high concentration phenols.