Structure-activity Relationship of Organic Amine Extractants and Their Solvent Extraction of Vanadium

The structure-activity relationship of organic amine extractants and their mechanism of solvent extraction of vanadium were analyzed.The results show that,organic amines,characterized by anion exchange and N atom as extraction functional group,belong to the alkaline extractants.Primary and tertiary amines are usually protonated in an acidic solution system to form the ammonium salts,while the quaternary ammonium salt does not require protonation.Primary amine,commonly used to extract vanadium from leaching solution of vanadium-chromium slag,can form a complex with hydrogen bonds to selectively extract vanadium preferentially,and the optimal extraction pH with a primary amine is generally less than 4.Tertiary amine can form an association with the vanadium-containing anion to extract vanadium,and the better extraction performance can be achieved at lower pH values.Especially,it shows excellent properties for extracting vanadium from leaching solution with high content of iron.However,tertiary amine also has disadvantages of small saturation capacity,large consumption and being liable to produce the third phase.The quaternary ammonium salt,the strong alkaline,can extract vanadium by ion exchange between vanadium anion and Cl^-,but quaternary ammonium salt has some disadvantages such as low saturation capacity and long phase separation time.The research progress of solvent extraction of vanadium by organic amine extractants was reviewed.Meanwhile,the future research directions including exploring of optimum extraction pH value,improving the performance of modifier,synergistic extraction with other extractants,optimizing the process before solvent extraction,strengthening mechanism research on solvent extraction of vanadium by amines,and developing new types of efficient and adaptable amine extractants,were proposed.