Boiling point of aqueous solutions of mate (Ilex Paraguariensis): Modeling and simulation of a batch evaporator

Experiments were carried out to determine the boiling point of aqueous solutions of soluble powder extracts of mate (Ilex paraguariensis) using a simplified ebuliometer. The consistency of the apparatus was checked based on a comparison between preliminary experimental results of this property and analogous data available in the literature for pure solvents (water, acetone and alcohol) and sucrose solutions at atmospheric pressure. The effects of mass fraction of solids and pressure on the boiling point elevation (BPE) of solutions of mate extracts were investigated in the range of 0.1-0.5 and 24.0-91.4 kPa, respectively. In these operating conditions the boiling points were in the magnitude of 64-101 °C, what means a maximum BPE close to 4 °C. All these experimental results and the influence of investigated factors were correctly reproduced with two empirical and one thermodynamic model early reported in the literature. The tuned parameter of the Clausius-Clapeyron equation revealed a molar mass of solute equal to 138 kg kmol−1. Experimental results of specific heat from 1528 to 4184 J kg−1 °C−1 and apparent density varying between 260 and 1000 kg m−3 were obtained for the investigated solutions of mate extracts in a calorimeter (method of mixtures) and a pycnometer at 25 °C. An energy equation, a water and a global mass balance were presented to mathematically describe experiments of concentration of aqueous solutions of mate extracts in a batch evaporator at 64.5 and 91.4 kPa.