The purpose of the present study is the development of a kinetic model to predict and understand the dissolution of crystalline alpha-glucose in 2-methyl 2-butanol. The model takes into account three processes that might control the dissolution rate of alpha-glucose crystals. The first step, the detachment of alpha-glucose molecules from the solid surface at the solid-liquid interface, is characterised by k(R), the time-independent rate constant for interfacial reaction. The second step, the mass transport of alpha-glucose from the solid-liquid interface to the bulk solution across the boundary layer, is characterised by k(T)(L(t)), the rate constant for transport which depends on the particle size, L(t), and hence on time. The third step is the mutarotation of alpha-glucose in solution, characterised by the forward mutarotation kinetic constant, k(1). The constants k(R) and k(1), are obtained by fitting the model to the experimental data of alpha- and beta-glucose concentration in the bulk as a function of time. k(T)(L(t)) is estimated using correlations based on geometry, operational conditions and alpha-glucose particle size. The particle size distribution of the primary solid particles was experimentally determined. The model fits well the experimental results, and reveals that, for stirring speeds between 300 and 700 rpm, both transport and interfacial reaction share the control of the dissolution rate of alpha-glucose in 2-methyl 2-butanol.
- alpha-glucose crystals
- kinetic model