Aqueous phase diagrams containing oxalic acid at 303.15 K

• Published in: Fluid phase equilibria Vol. 134; no. 1; pp. 201 - 211
• Main Authors: Barnes, Norma, de Doz, Mónica Gramajo, Sólimo, Horacio N.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.06.1997; Elsevier Science
• Subjects: Chemical equilibria; Chemistry; Data; Exact sciences and technology; General and physical chemistry; Liquid-liquid equilibria; Others (including liquid-liquid-vapor equilibria); Phase equilibria; Solid-fluid equilibria; Ternary aqueous oxalic acid systems; Data; Ternary aqueous oxalic acid systems; Solid-fluid equilibria; Liquid-liquid equilibria; Chemical equilibria; Water; Chemical equilibrium; Ternary system; Oxalic acid; Phase diagram; Liquid solid equilibrium; Partition coefficient; Selectivity; Experimental study; Phase equilibrium; Liquid liquid equilibrium
• ISSN: 0378-3812; 1879-0224
• DOI: 10.1016/S0378-3812(97)00035-6

Phase diagrams of ternary systems: water + oxalic acid + (1-pentanol or + isobutyl acetate or + methyl isobutyl ketone) were obtained at 303.15 K. The system containing 1-pentanol was revised [Faizal et al., J. Chem. Eng. Data 35 (1990) 352–354] in order to show the presence of the dihydrate of oxalic acid, by means of the analysis of the solid phase using FT-IR spectrum, melting point data, and acid-base titration. Experimental results show that all aqueous oxalic acid systems have one region where both acid forms are mixed, and three solid-liquid zones where the solid is the hydrated oxalic acid. The recovery of oxalic acid from aqueous solutions was evaluated analyzing their distribution coefficients, selectivities and distribution curves on a solvent-free basis. None of the three solvents studied here were found suitable for oxalic acid extraction processes, because distribution coefficients are always smaller than 1 and selectivities are not high enough.