Effect of KCl and Na₂SO₄ on the Solubility of Glycine and dl-Alanine in Water at 298.15 K

Abstract

The solubility of glycine and dl-alanine in aqueous systems of KCl and Na2SO4 at 298.15 K was measured at different salt concentrations using the analytical gravimetric method. The experimental data obtained in this work and those previously reported in the literature for the same systems were compared, and it was possible to show a big discrepancy for the water−KCl−amino acid systems and a very satisfactory agreement for the water−Na2SO4−amino acid systems. The solubility data from this work and the activity coefficients data from literature were used to explore the potentialities of the Pitzer−Simonson−Clegg equations for the thermodynamic description of the ternary systems water−KCl with glycine or dl-alanine at 298.15 K. This model, with five adjustable parameters, gives a global root-mean-square deviation of 0.0036 for the correlation of the activity coefficients and 0.63 g/(kg of water) for the solubility in those ternary systems.

Chemical Transfer Energetics of a Series of Homologous α-Amino Acids in Quasi-Aprotic 2-Methoxyethanol–Water Mixtures

“…Here the standard deviations (s f ) were estimated for all solubility values to characterize the precision and are shown in Table 1. Here it is important to note that the most of the solubility data of the experimental amino acids in pure water corroborate excellently with the literature data that are summarized in Table S1 [12,19,20,[24][25][26][27][28][29][30][31][32].…”

Solubility of l-serine, l-threonine and l-isoleucine in aqueous aliphatic alcohol solutions

“…The experimental procedure is very similar to that published previously [1,23,24] and so, only brief details are given here. It consists in the preparation of a saturated solution at constant temperature (±0.1 K).…”

“…When w alcohol < 0.8, the gravimetric method is used. Each experimental point is an average of at least three different measurements obeying the following criterion: the quotient 2s/solubility × 100 should be lower than 0.2, where s is the standard deviation within a set of different experimental results [1,23,24].…”

Pitzer and Pitzer–Simonson–Clegg modeling approaches: Ternary HCl+1-propanol+water electrolyte system

“…A survey of literature shows, as well, that the application of a complete PSC approach for modeling electrolyte in mixed solvent systems is limited only to the work of two research groups [10][11][12]. This might be due to the apparent complexity of the related relations, the number of involved ion-interaction parameters, and would explain why some authors have used simplified version of the PSC models [13][14][15][16][17][18][19].…”