Equilibria investigation and extraction thermodynamic of extracting (o-/m-/p-)-cresol from aqueous solution using 1-dodecanol

Abstract

1-Dodecanol has good extraction efficiency of cresols from aqueous solution. The liquid-liquid equilibrium (LLE) data of ternary system 1-dodecanol-(o-/m-/p-)-cresol-water were determined at 298.15 K, 313.15 K, 323.15 K, 333.15 K and 343.15 K under atmospheric pressure. The Hand and Othmer-Tobias equations were used to test the reliability of the experimental tie-line results. The results show that the measurement data has high consistency. The LLE data were correlated by non-random two-liquid (NRTL) and universal chemical activity coefficient (UNIQUAC) models. The experimental results show that the correlation coefficients of both models exceed 0.995. All root mean square deviations (RMSDs) between the calculated values from the single temperature NRTL model, the UNIQUAC model and the multiple temperatures NRTL model and the experimental data are <1.5%. It shows that three models can predict LLE data well. The obtained parameters could be applied to simulate extraction process of cresols from coal chemical wastewater by 1-dodecanol as an extractant. Furthermore, the multiple temperatures NRTL model can predict the LLE data at any temperature in the measured range so it has greater universality. The van't Hoff equation is used to correlate the relationship between distribution coefficient and temperatures and estimate the enthalpy of the extraction process, which represents that extraction of cresols from aqueous solution by 1-dodecanol is an exothermic process. The lower the extraction temperature is, the more favorable the extraction is.