Solubility of Organics in Triethylene Glycol: Phase Equilibrium Modelling Using the Dortmund and LYNGBY Modified UNIFAC Models

Abstract

Abstract-This work is an attempt to predict the solubility of 60 volatile organic compounds (VOCs) in triethylene glycol aimed at thermodynamically testing the suitability of this solvent as an absorbent for the selected organics. The VOC main groups studied were alkanes, alkenes, alkynes, aldehydes, carboxylic acids and alcohols. The Modified UNIFAC Dortmund and Lyngby models were to study the required phase equilibrium as a function of temperature and composition. Triethylene glycol was found to be suitable for the absorption of low molecular weight aldehydes, alcohols and carboxylic acids. Generally, the infinite dilution activity coefficients computed in this study were low (below 100) indicating that the polymeric solvent studied in this work gave favourable phase equilibrium compared to water, the common industrial solvent. The solubility of VOCs was also found to decrease with increase in solute molecular weight. Compared with literature findings, the Dortmund performed better than the Lyngby procedure. However both models failed to accurately predict phase equilibrium behaviour. The authors therefore agree with literature findings that a specialised group interaction needs to be created for this solvent in the UNIFAC models in order to satisfactorily predict activity coefficients for the studied binary interactions.Index Terms-Absorbent, phase equilibria, solubility, volatile organic compounds.

Liquid–Liquid Equilibrium for the Binary Mixtures of Butyl l-Lactate + Water and Butyl Lactate + Water at 74.6 kPa

“…The outcomes of molecular dynamic computations have demonstrated that UNIQUAC frequently exhibits a tendency to excessively rectify deviations associated with random mixing due to the significant magnitudes observed in the arguments of the Boltzmann factors. Consequently, UNIQUAC tends to fall short in some cases in terms of precision when utilized for liquid–liquid equilibrium (LLE) calculations, as compared to the NRTL model . In comparison to NRTL, UNIQUAC exhibits greater mathematical complexity; however, it offers three distinct advantages when employed in thermodynamic modeling: First, the UNIQUAC model encompasses solely two adjustable parameters per binary, as opposed to the three parameters required by NRTL.…”

“…Remarkably, its applicability extends to lactate compounds, − including butyl lactate, , while also including partially miscible systems as well as completely miscible mixtures . This versatile model has thus garnered recognition and utility in various complex scenarios, making it a useful tool for comprehensive research in the realm of intermolecular interactions and phase equilibria analysis …”

“…In a similar situation, the Universal Quasichemical (UNIQUAC) activity model has been chosen on comparable grounds to the NRTL model, as it finds applicability across a diverse range of nonelectrolyte mixtures encompassing both nonpolar and polar fluids, ,,,,− including partially miscible mixtures . The outcomes of molecular dynamic computations have demonstrated that UNIQUAC frequently exhibits a tendency to excessively rectify deviations associated with random mixing due to the significant magnitudes observed in the arguments of the Boltzmann factors.…”

“…Consequently, UNIQUAC tends to fall short in some cases in terms of precision when utilized for liquid−liquid equilibrium (LLE) calculations, as compared to the NRTL model. 39 In comparison to NRTL, UNIQUAC exhibits greater mathematical complexity; however, it offers three distinct advantages when employed in thermodynamic modeling: First, the UNIQUAC model encompasses solely two adjustable parameters per binary, as opposed to the three parameters required by NRTL. Second, the temperature dependence of UNIQUAC's parameters tends to be comparatively reduced.…”