Kinetic modeling of glucose and fructose dissolution in 2-methyl 2-butanol

With the objective of developing simulation models for sugar bioconversion processes in non-aqueous media, the present study investigated the dissolution kinetics of glucose and fructose in 2-methyl 2-butanol at temperatures between 20 degrees C and 80 degrees C. For both sugars a two-phase dissolution process was observed, characterized by an initially fast dissolution lasting a few minutes, followed by a much slower dissolution phase extending up to 24 h. The experimental results are described by a combined sugar dissolution and mutarotation kinetic model that considers the dissolution of the sugar anomeric form present in the solid particles, namely alpha-D- glucopyranose and beta-D-fructopyranose, and its subsequent mutarotation in solution. The initial dissolution step is assumed limited by the solute transport from the surface to the bulk solution, and the corresponding sugar transport coefficient evaluated from established mass transport correlations. The second slower dissolution phase is solely controlled by the sugar mutarotation rate, and modeled as a first-order reversible reaction. The determined values of the mutarotation rate and equilibrium constants can be related to the solution temperature by an Arrhenius and Van't Hoff relationship, respectively. (C) 2008 Elsevier B.V. All rights reserved.