Separation of p-Aminobenzoic Acid by Reactive Extraction in the Presence of 1-Octanol as Phase Modifier

The paper presents the studies on reactive extraction of p-aminobenzoic acid with two extractants (Amberlite LA-2 and D2EHPA) dissolved in two solvents with different dielectric constants (n-heptane, dichloromethane), at various 1-octanol concentrations in the solvent. The addition of 1-octanol induced the increase of the extraction efficiency, the most important influence being recorded for the solvent with lower polarity (n-heptane). Moreover, the volumetric fraction of alcohol controls the number of extractant molecules participating in the interfacial product formation. This effect was more important for the extraction in low-polar solvent and was concretized in the reduction of number of Amberlite LA-2 molecules included in the interfacial compound from 3, in the absence of alcohol, to 1, for φ = 20 % alcohol. Indifferent to alcohol fraction in organic phase, for the reactive extraction with D2EHPA in n-heptane, the number of extractant molecules decreased from 2, in the absence of 1-octanol, to 1 in the presence of 1-octanol. The limitation of solute solvation by extractant due to the increase of solvent polarity led to the reduction of the extraction constant and to the amplification of the differences between the extraction constants obtained for the same extractant and the two solvents