Protic amine/acid mixtures as solvents for the extraction of aqueous zinc salts: A mechanistic study

Mixtures based on trihexylamine and cyclic carboxylic acids (aromatic and non-aromatic) were used as solvents for the extraction of zinc salts from aqueous phases via liquid-liquid extractions. The anions of the zinc salts were chosen to represent a range of kosmo-/chaotropic characters, and their influence on the extractions was observed. The extraction studies were supplemented by investigation of local liquid structure through small-angle x-ray scattering (SAXS). The results indicate that extraction is strongly influenced by the Hofmeister effect, but the local liquid structure appears insensitive to anion kosmo-/ chaotropic character. In contrast to similar extraction studies, the strength of the Hofmeister effect did not change according to the composition of the mixtures.(c) 2023 Elsevier B.V. All rights reserved.

Automated summary

Mixtures of trihexylamine and cyclic carboxylic acids were used as solvents for extracting zinc salts from water. The choice of zinc salt anions represented a range of solvation properties, and their influence on extraction was investigated. Small-angle x-ray scattering was used to study the liquid structure. The results showed that extraction was strongly affected by the Hofmeister effect, but the local liquid structure was not sensitive to the solvation properties of the anions. Unlike similar studies, the strength of the Hofmeister effect did not change with the composition of the mixtures. (c) 2023 Elsevier B.V. All rights reserved.