Abstract

--- - Vapor - liquid - liquid equilibrium (VLLE) for water + MTBE + ethanol and water + MTBE 1-butanol ternary systems have been measured in a modified dynamic Guillespie type cell at the isobaric condition of 101.3 kPa and over the temperature range from 325.6 to 328.9 K for water + MTBE + ethanol mixture and from 329.5 to 355.1 K for water + MTBE + 1-butanol mixture. The quality of the measured data is thermodynamically validated by the L/W Wisniak's consistency point- point test. According to the experimental results, the liquid - liquid equilibria are Type I for water + MTBE + ethanol mixture and Type II for water + MTBE 1-butanol mixture. The VLLE for water + MTBE + ethanol mixture dis- plays heterogeneous ternary azeotrope whereas the water + MTBE 1-butanol mixture is a zeotropic ternary mixture. The experimental VLLE data for both ternary mixtures are correlated by a modified version of the nonrandom two-liquids (NRTL) activity coefficients model, which incorporates a ternary contribution. This ternary contribution reduces the global average absolute deviation from 5 % to 1.3 % for water + MTBE + ethanol mixture and from 3.1% to 1.9 % for water + MTBE 1-butanol mixture. - The experimental isobaric VLLE data of the ternary mixtures are also accurately modeled by applying the Peng-Robinson Stryjek-Vera equation of state appropriately extended to mixtures employing the modified Huron-Vidal mixing rule with the NRTL activity coefficient model. This model allows directly transferring the experimental excess Gibbs energy function to the EoS model for equilibrium calculation purposes. This theoretical framework shows that experimental VLLE data can be accurately predicted and provide a route to interpolate values of the phase equilibrium. (C) 2020 Elsevier B.V. All rights reserved.