Determination and Chemical Modeling of Phase Equilibria for the Glycine–KCl–NaCl–H₂O System and Its Application To Produce Crystals with Anticaking Characteristics

Abstract

The phase equilibria of the glycine−KCl−NaCl−H 2 O system were determined in the concentrations up to 3.33 mol•kg −1 over the temperature range from 283.2 to 363.2 K using a dynamic method. A rigorous chemical model for the glycine−KCl−NaCl−H 2 O system was established by the Pitzer model with the help of an OLI platform. With the equilibrium constants of dissociation reactions obtained by standard-state thermodynamic data, the new Pitzer model parameters were harvested by regressing solubility of the system. These newly obtained parameters were used to accurately predict the multiple saturated points at the temperature range from 283.2 to 363.2 K. The phase behavior of the ternary glycine−KCl−H 2 O and glycine−NaCl−H 2 O system at 298.2 and 343.2 K were successfully visualized with lucidity on an equilateral triangle. To investigate the effect of glycine on the morphology of KCl, the KCl crystals were produced from glycine solution with different concentration (17−25% w/v) by evaporation at ambient temperature. The glycine (25% w/v)-modified KCl crystal changed its morphology from native cubic to hexagonal prism form with the angle of repose from 32°to 23.8−25.8°, indicating a good flowability and anticaking characteristics. Finally, KCl supersaturation variation with evaporation time was simulated with aid of the chemical model established in present study to elucidate the influence of glycine concentration on the anticaking characteristics of KCl crystal. All the results generated from this study will provide the fundamentals for industrial application to produce crystals with anticaking characteristics.

Solid–Liquid Equilibria for the Glycine–Alcohol–NaCl–H2O System

“…In the present study, the solubility of glycine in alcohol (ethanol/1-propanol)–H 2 O and in alcohol (ethanol/1-propanol)–NaCl–H 2 O systems was measured from 283.15 to 333.15 K. The solubility of NaCl in glycine–alcohol (ethanol/1-propanol)–H 2 O was also measured from 283.15 to 333.15 K. The experimental data for the glycine–ethanol–H 2 O, glycine–ethanol–NaCl–H 2 O and glycine–1-propanol–H 2 O systems together with reported data of glycine–NaCl–H 2 O, glycine–ethanol–H 2 O 6 and glycine–1-propanol–H 2 O 6 were correlated by MSE model parameters. A new single set of middle range and UNIQUAC parameters were obtained that are capable of calculating SLE in the experimental range for the systems correlated.…”

“… a Standard uncertainties u are u ( T ) = 0.10 K, u r ( p ) = 0.05, u r ( x (ethanol)) = 0.005, and u ( m (glycine)) = 0.1 mol·kg –1 . b Mole fraction of 1-propanol in the 1-propanol–NaCl–H 2 O system. c The solubility of glycine in NaCl–H 2 O was taken from Gao and Li …”

“…Dalton and Schmidt reported the solubility of several amino acids including glycine in water at the temperature range from 273.15–333.15 K. Cohn et al measured the solubility of glycine in water and ethanol–water mixtures at 298.15 K. Bouchard et al calculated the solubility of glycine in aqueous solutions of alcohols, including ethanol at 310 K. For mixed-solvent systems, Ferreira et al presented solubility data of glycine in ethanol–water, 1-propanol–water, and 2-propanol–water at different temperatures and Orella and Kirwan demonstrated solubility data of glycine in 1-propanol–water and 2-propanol–water at 298.15 K. Cao et al and Lu et al published solubility data of glycine in the ethanol–water system at 278.15–328.15 K and at 298.15 K, respectively. In aqueous electrolyte solutions, the measurement of solubility of glycine was carried out with NaCl and KCl by Khoshkbarchi and Vera, and Gao and Li . Ansari and Li determined the solubility of glycine in single electrolyte MgCl 2 –H 2 O and mixed electrolyte NaCl–MgCl 2 –H 2 O systems in the temperature range of 283–333.15 K.…”

“…Ferreira et al modeled the solubility data of glycine in ethanol solutions at 298.15, 313.15, 323.15, and 333.15 K and in 1-propanol solutions at 298.15 K using the nonrandom two-liquid (NRTL) model. Orella and Kirwan , applied excess solubility and the Wilson approach to simulate the solubility of 5 amino acids, including glycine in 1-propanol, 2-propanol at 298.15 K. For the glycine–NaCl–water system, Gao and Li used the Pitzer model, whereas Khoshkbarchi and Vera applied the perturbed hard-sphere model to correlate experimental data.…”

Modelling the effects of ethanol on the solubility of the proteinogenic amino acids with the NRTL, Gude and Jouyban-Acree models

“…These models include calculating partition coefficients 11 , using regressed coefficients 12 , examining non-ideality 13 , measuring and modelling activity coefficients [14][15][16][17] , activities 18 and applying a modification of the Wilson model 19 . Other models have been applied to model the solubility of amino acids in salt solutions [20][21][22][23][24][25][26][27] . Only a few models have been proposed to describe the solubility of α-amino acids in ethanol/water systems, but these manuscripts focus on a single model and only a few α-amino acids [28][29][30] .…”