NaCl and KCl effect on (vapour + liquid) equilibrium of binary, ternary and quaternary systems involving water, ethanol and glycerol at low pressures

• Salt effects on VLE data of systems present on biodiesel production, mainly in glycerol purification, are shown.
• NaCl effect was not observed in the system {ethanol + NaCl + glycerol}.
• Salting-out and salting-in effects were simultaneously observed in ternary systems.
• VLE were also obtained for the quaternary system {water + ethanol + NaCl + glycerol}.

Isobaric (vapour + liquid) equilibrium data at pressures of (14.0 to 91.2) kPa over the whole composition range were measured for binary systems of (ethanol + glycerol), (water + NaCl) and (water + KCl). Moreover, ternary systems (glycerol + ethanol + NaCl), (glycerol + water + NaCl) and (glycerol + water + KCl) and quaternary system of (water + ethanol + NaCl + glycerol) were measured at 91.2 kPa. All data were obtained using a Othmer-type ebulliometer. Due to the low solubility of NaCl in ethanol, it was not observed the salt effect on the VLE for the system (ethanol + NaCl + glycerol). The presence of salt (NaCl or KCl) increased the boiling point of water, and this effect was less pronounced at lower pressures, probably due to the low resistance to volatilization at such pressures. Simultaneous salting-in and salting-out effect were observed in the systems (water + NaCl + glycerol) and (water + KCl + glycerol), which is characterized in literature as a anomalous behaviour.