Abstract
Extraction of various dicarboxylic acids (maleic, malic, malonic, succinic, and tartaric) by acid-base couple (ABC) extractants was studied. The main extraction mechanisms were found to be ion-pair and hydrogen-bond formation. The relative contribution of each mechanism and extraction efficiency were found to be controlled by parameters such as acid-base properties and hydrogen-bonding capability of the components of the ABC extractants and those of the extracted dicarboxylic acid. Typical ion-pair formation was observed for extraction of all tested acids with extractants composed of a primary amine and a fatty carboxylic acid. Typical H-bond formation is shown for extraction of most acids with an extractant composed of a tertiary amine and a diester of phosphoric acid. All other cases had mixed contributions. Strong interactions between the extractant components limited extraction in both mechanisms. The results were also analyzed in comparison with the extraction of monocarboxylic acids. Dicarboxylic acids are better extracted in those cases where the acid-base properties of the system components favor ion-pair formation. In extraction through H-bonds, on the other hand, the greater hydrophilicity of the dicarboxylic acids limits the extraction.
| Original language | English |
|---|---|
| Pages (from-to) | 51-67 |
| Number of pages | 17 |
| Journal | Solvent Extraction and Ion Exchange |
| Volume | 22 |
| Issue number | 1 |
| DOIs | |
| State | Published - Jan 2004 |
Keywords
- ABC extractants
- Dicarboxylic acids
- Extraction
- H-bond formation
- Ion-pair formation