Phase Equilibrium Behavior in Mixtures Containing Tributyl Citrate, Citric Acid, Butan-1-ol, and Water

Abstract

This work focused on the development of the phase equilibria models required to describe the behavior of mixtures involved in the synthesis of tributyl citrate (TBC) via esterification of citric acid (CA) and butan-1-ol (BuOH). Vapor−liquid equilibrium (VLE) for the mixture TBC−BuOH, liquid−liquid equilibrium (LLE) for the ternary mixture TBC− H 2 O−BuOH, and solubility data for the mixture CA−BuOH−TBC were measured at different temperatures. The thermodynamic consistency was verified with the Wisniak test for VLE data, and the LLE data exhibited linear behavior in an Othmer and Tobias plot. Anhydrous citric acid was characterized by differential scanning calorimetry exhibiting a melting point of 424.9 K, an enthalpy of fusion of 59.2 kJ/mol, an average heat capacity of 255.48 J/mol•K in the evaluated temperature range (320−375 K), and a change of heat capacity from solid to liquid of 236 J/mol•K. Together with reported equilibrium data from the open literature, and the evaluated physicochemical properties, the measured equilibrium data were regressed with the UNIQUAC equation to fit the binary interaction parameters of the components in the mixture. The obtained model agrees well with the whole set of experimental data and can be used for further process design.

Solid–Liquid Equilibria and Characterization of the Reaction Mixture To Produce Sucrose Palmitate in Solvent-Free Media

“…The solubility was then evaluated by determination of concentration in the liquid phase by the implemented HPLC method. The reliability of this solubility determination methodology was verified in a previous publication …”

“…It was assumed that the solution density did not change with the dissolution of the sucrose esters. The surface tension of a sucrose ester solution in water has been reported in various studies ,− . The corresponding surface tension of sucrose palmitate with approximately 70% monoester at 288 K was reported to be 37.2 mN/m .…”

“…The reliability of this solubility determination methodology was verified in a previous publication. 10 For the chromatographic analysis, the processed sample was analyzed by mean of a Dionex UltiMate 3000 (Thermo Scientific, USA) HPLC, equipped with a Dionex Corona Veo RS CAD (Thermo Scientific, USA) and using a LiChros-pher100 RP-18 5.0 μm column (125 × 4.0 mm Merck, Germany). The system operated at 313 K using a gradient elution of ACN and deionized water from 80/20 ACN/W v/v to 100 v/v in 8 min, and then isocratic at 100 v/v for 35 min with a flow of 0.5 mL/min.…”

Dibutyl Citrate Synthesis, Physicochemical Characterization, and Px Data in Mixtures with Butanol

“…As the evaluated mixture was multicomponent, mostly containing other citrate species, they were also considered in the model regression. The binary interaction parameters with the other components were obtained from a previous report from the authors, 21 and they are listed in Tables S4 and S5 of the Supporting Information. The correspondent binary parameters with MBC were estimated using UNIFAC predictions.…”

Tributyl Citrate Production via Reactive Distillation—Conceptual Design and Pilot-Scale Validation

“…In this regard, this work deals with the fundamentals of the production of TBC via RD. Initially, the conceptual design of the process was accomplished based on validated kinetic and thermodynamic models. − This was done using novel reactive residue curve maps (RRCMs) applied to mixtures of six components. Then, a computer-aided RD model was developed and implemented in Aspen Plus, exploring different operating configurations that help to guide a further experimental exploration of the process.…”