The use of a separability coefficient for the screening of vapor–liquid enrichment by TG-FTIR analysis

A novel methodology for the screening of vapor–liquid enrichment in binary homogeneous systems is presented. The methodology is based on the estimation of a separability coefficient from experimental data obtained by thermogravimetry with Fourier transform infrared spectrometry (TG-FTIR) of the evolved gases. The technique may be applied to the investigation of any system where the separation of the contributions of each component to the recorded IR spectra is possible. Experimental tests on several binary zeotropic and azeotropic mixtures were carried out at atmospheric pressure and the results were compared to available relative volatility data. The separability coefficient obtained by a batchwise evaporation of binary mixtures in TG-FTIR experiments was shown to reasonably approach the trend of relative volatility. The very limited amount of sample required for experimental runs (less than 30 μl/run) and the use of an internal calibration method make the TG-FTIR technique attractive for the preliminary screening of the separability of binary homogeneous mixtures.