Effect of the Charge and the Nature of Both Cations and Anions on the Solubility of Zwitterionic Amino Acids, Measurements and Modeling

摘要

The effect of the charge and the nature of both the cations and the anions of some electrolytic salts: sodium fluoride (NaF), potassium fluoride (KF), sodium bromide (NaBr), potassium bromide (KBr), sodium iodide (NaI), potassium iodide (KI), sodium sulfate (Na₂SO₄), potassium sulfate (K₂SO₄), calcium chloride (CaCl₂), and barium chloride (BaCl₂), on the solubility of zwitterionic amino acids (glycine, DL-alanine, DL-valine, and DL-serine) in aqueous solutions at 298.15 K are studied and discussed. A salting-in effect is observed for all amino acids under investigation with all electrolytes used in the present study, except for DL-alanine and DL-valine in aqueous solutions containing sodium fluoride where a salting-out effect was observed. The orders of the effect of the nature and the charge of both the anions and the cations are: F- < Cl- < Br- < I- < NO₃- < SO₄2-mathrm{F}^{-}<{}mathrm{Cl}^{-}<{}mathrm{Br}^{-}<{}mathrm{I}^{-}