Study On Liquid-liquid Extraction Of Phenols From Aqueous Solutions With Cineole

A large amount of phenolic wastewaters is produced during coal chemical industry,petroleum,pharmaceutical,phenol and phenolic resin industries.Phenol and its derivatives commonly exist in various kinds of phenolic wastewaters,and are the persistent organic compounds,which are highly toxic or not easy to degrade.Treatment of industrial wastewater containing phenols has been taken more seriously with the strict implementation of environmental protection standards.Solvent extraction is widely used in the treatment of industrial phenol wastewater because of the advantages of simple operation,low cost and high recovery rate in the process.It is necessary to select a suitable extractant,especially an environmental-friendly chemical extractant.In this work,we choose an organic solvent that can efficiently remove phenols from wastewater.C ineole(1,8-cineole,C10H18O),is an environmentally benign solvent with steady chemical properties and alternative sources.It has a very solubility in water,but a high selectivity to phenols and can efficiently extract phenolic substances from wastewaters.In this study,ternary and quaternary(water + phenolic compound + cineole)liquid-liquid equilibrium systems were determined experimentally to verify the feasibility of the treatment of phenol phenolic wastewaters with cineole.The experimental data may provide important experimental support and theoretical basis for the recovery and separation of phenolic harmful substances.In this work,four representative phenolic compounds(phenol,o-cresol,m-cresol,p-cresol)were selected as the research objects,and cineole was selected as an extractant for phenols-water mixtures.The liquid-liquid equilibria of 5 binary(water + 1,8-cineloe)and(water + phenol / o-cresol / m-cresol / p-cresol)systems,4 ternary(water + phenol / o-cresol / m-cresol / p-cresol + 1,8-cineloe)systems,and 3 quaternary(water + phenol + m-cresol + 1,8-cineloe)systems(mass ratio phenol : m-cresol = 1: 1,1: 3,3: 1)were determined experimentally with a tie-line method at T =(283.15,298.15,313.15)K under the atmospheric pressure.The extraction ability of 1,8-cineloe as an extraction agent and the effect of temperature on extraction were discussed.The results showed that 1,8-cineloe as an extractant exhibited high extraction ability for phenols from water solution.Lower extraction temperature was helpful to the increase of the extraction ratio for phenols.Moreover,the NRTL and UNIQUAC models were used to calculate the experimental LLE data;the interaction parameters of a binary part miscible system are determined by binary mutual solubility and thermodynamic conditions;the interaction parameters of the binary miscible system are calculated by the correlation calculation of the ternary liquid-liquid equilibrium experiment data.The results show that the both average root mean square deviation between the experimental results for the two models were 0.19%.The calculated results are in good agreement with the experimental data.In addition,the prediction of quaternary(water + phenolic compound + cineole)liquid-liquid equilibrium system was performed by using the known binary interaction parameters from the binary and ternary systems.The results showed that the average root mean square deviation between the experimental results and calculated by the N RTL and UNIQUAC models were 1.11 % and 0.95 %,respectively.The calculated results are in agreement with the experimental data.