Model-based measurement of diffusion using Raman spectroscopy

• Published in: AIChE journal Vol. 49; no. 2; pp. 323 - 334
• Main Authors: Bardow, André, Marquardt, Wolfgang, Göke, Volker, Koss, Hans-Jürgen, Lucas, Klaus
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 01.02.2003; Wiley Subscription Services; American Institute of Chemical Engineers
• Subjects: Condensed matter: structure, mechanical and thermal properties; Diffusion and ionic conduction in liquids; Diffusion and thermal diffusion; Exact sciences and technology; Physics; Transport properties of condensed matter (nonelectronic); Transport properties; Multicomponent mixture; Toluene; Measuring methods; Experimental study; Binary mixtures; Raman spectroscopy; Cyclohexane; Modelling; Diffusion coefficient; Liquid mixtures; Design of experiments; Organic compounds
• ISSN: 0001-1541; 1547-5905
• DOI: 10.1002/aic.690490205

The measurement of diffusion coefficients in multicomponent liquid mixtures is still an open question. A new technique aimed at overcoming this deficiency is presented. It is based on Raman spectroscopy, which has been extended to obtain liquid concentration data of all components in a mixture simultaneously with high temporal and spatial resolution. The following data analysis uses model‐based methods. This provides a very flexible framework, allowing substantial reduction of experimental effort and time and the direct estimation of the diffusion coefficient as a function of concentration. Furthermore, the experimental procedure is improved using optimal experimental design techniques. This new methodology is validated for binary mixtures.