A Methodology for the Screening of Vapor-Liquid Enrichment and the Identification of Azeotropic Binary Mixtures by TG-FTIR
Federica BARONTINI Gruppo Nazionale per la Difesa dai Rischi Chimico-Industriali ed Ecologici, Consiglio Nazionale delle Ricerche, via Diotisalvi n.2, 56126 Pisa (Italy) Elisabetta BRUNAZZI, Valerio COZZANI Dipartimento di Ingegneria Chimica, Chimica Industriale e Scienza dei Materiali, Università degli Studi di Pisa, via Diotisalvi n.2, 56126 Pisa (Italy)
A methodology for the screening of vapor-liquid enrichment is presented. The technique also allows the identification of azeotropic points, if present, and the estimation of the azeotropic composition. A separability coefficient was defined, calculated on the basis of experimental data from simultaneous thermogravimetric and infrared spectrometric (TG-FTIR) measurements. Experimental tests on several binary zeotropic and azeotropic mixtures were carried out at atmospheric pressure and the results were compared to available literature data. Although the dynamic configuration of the TG-FTIR experiments causes the method to be less accurate than conventional techniques, its main advantages are the very limited amount of sample required for experimental runs (less than 30*l/run), the use of an internal calibration method, and the achievement of information on mixture separability over a wide interval of compositions available by a single run. The technique may be applied for the investigation of any system where the separation of the contributions of each component to the recorded IR spectra is possible. The methodology proved to be potentially useful for a preliminary screening of the separability of binary homogeneous mixtures. The much lower quantities of samples required make the TG-FTIR technique attractive due to the significant reduction of time, costs and of safety and disposal problems associated to conventional methods.
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