Temperature Dependent Solubility of α-Form l-Glutamic Acid in Selected Organic Solvents: Measurements and Thermodynamic Modeling

Abstract

In this study the solubility of α-form l-glutamic acid in the six organic solvents methanol, ethanol, 1-propanol, acetone, formic acid, and dimethyl sulfoxide (DMSO) was measured by a static analytic method. The measurements were carried out over the temperature range 278–355 K at around 5 K intervals, and the equilibrium concentration was determined by the gravimetric method. The experimental results show that formic acid has the highest solubility to α-form l-glutamic acid while the other solvents have the solubility order water, acetone, 1-propanol, ethanol, methanol, DMSO, and acetic acid. The hypothetical enthalpy of fusion and melting temperature of l-glutamic acid are estimated. Several commonly used thermodynamic models, including the empirical van’t Hoff equation and the Wilson, NRTL, and UNIQUAC equations, were applied to correlate the experimental solubility data. The binary interaction parameters of the above models are found to have a linear dependency on temperature, and the coefficients were regressed. It was found that all these models can satisfactorily reproduce the experimental solubility and the UNIQUAC equation can provide the best correlation results with an overall standard deviation of 2.7 × 10–5.

Measurement and correlation of the solubility of genistin in eleven organic solvents from T=(283.2 to 323.2)K

“…Parameters of the kh model (A4) and NRTL model (A6) correlated from experimental values for genistin in the investigated solvents.and a reasonable assumption, the following expression was obtained from equation (A1)[32]:…”

Measurement and Correlation of the Solubility of Gestodene in 11 Pure and Binary Mixed Solvent Systems at Temperatures from 283.15 to 323.15 K

“…As a suitable model for calculating the activity coefficient of liquid solute, the equation was widely used in predicting the calculation of solubility, and the model is significant for the melting temperature, melting enthalpy, and activity coefficient of the solute. The expression of the equation is described as follows …”

Correlation and Thermodynamic Analysis of Solubility of Mesotrione in Pure Solvents

“…where ΔH m and T m stand for the enthalpy of fusion and melting temperature of the solute, respectively, and γ i is the activity coefficient of solute in the saturated solution which can be calculated by the NRTL model. 9,10 The definition of these terms can be expressed as…”

“…According to the solid–liquid phase equilibrium theory and the solute–solvent interactions, the NRTL equation can be simplified and expressed by eq where Δ H m and T m stand for the enthalpy of fusion and melting temperature of the solute, respectively, and γ i is the activity coefficient of solute in the saturated solution which can be calculated by the NRTL model. , …”