Boiling point of aqueous d-glucose and d-fructose solutions: Experimental determination and modeling with group-contribution method

Boiling points of aqueous solutions affect the design and operation of evaporators. Hence, boiling points of aqueous solutions of d-glucose and d-fructose were experimentally determined at soluble solute concentration from 10 to 60% sugar by mass and pressure from 20 to 93.6 kPa. The experimental data were correlated with data predicted by the calculation of the activity coefficients with the UNIFAC-Lyngby model using different approaches for decomposition of the molecular structure: the aliphatic groups and the cyclic groups. Moreover, the rise in experimental boiling point of the aqueous sugar solutions was evaluated by the Dühring's rule. It was observed that the cyclic approach resulted in better accuracy for liquid–vapor equilibrium prediction and the non-ideality of these solutions are relevant in the boiling point rise, confirming that the rise in boiling point of aqueous d-glucose and d-fructose concentrated solutions is significant to the design of heat and mass transport operations.