Phase Equilibria in a System Formed by Potassium Oxalates and Citrates

The authors study the effect different factors (having a seed of a certain phase, mixing, and period of holding while preparing the initial heterogeneous mixtures, acidity) have on the conditions of crystallization of solid phases from solutions in the K⁺, H⁺||C₂O \(_{4}^{{2 - }}\) (abbr. Ox^2–), and C₆H₅O \(_{7}^{{3 - }}\) (abbr. Cit³⁻)–H₂O systems. The solubilities of salts of potassium hydrocitrate K₂HC₆H₅O₇ (K₂HCit) and potassium hydrooxalate KHC₂O₄ (KHOx) with pH 2.5–5 are determined at 298.15 K (25°C) in the 10–40 wt % and 0–20 wt % ranges of concentrations, respectively. Areas of the crystallization of salts of KH₂Cit⋅2H₂O, K₂HCit⋅0.5H₂O, KHOx, 2K₂Ox⋅H₂Ox⋅2H₂O, and K₂Ox⋅H₂O are identified.