Structure-activity Relationship of Organic Amine Extractants and Their Solvent Extraction of Vanadium
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摘要: 分析了有机胺类萃取剂的构效关系及其萃钒机理,结果表明:有机胺类萃取剂是以阴离子交换为特征、N原子为萃取功能基的碱性萃取剂;伯胺和叔胺在酸性体系中发生质子化后形成铵盐,季胺盐类不需质子化;伯胺与氢键形成缔合物从而选择性优先萃钒,常用于萃取钒铬渣浸出液中的钒,传统单一伯胺最优萃取pH值一般小于4;叔胺与体系中含钒配合阴离子形成缔合物从而萃钒,其在更低pH值下萃取性能更好,尤其在萃取含铁杂质的浸出液中钒时性能优良,但叔胺饱和容量小、萃取剂消耗量大且易产生第三相;强碱性季胺盐与含钒溶液接触时,含钒阴离子与萃取剂中Cl-发生交换,从而使钒进入有机相,季胺盐类存在饱和容量低以及分相平衡时间较长的问题。评述了近年来有机胺类萃取剂萃钒的研究进展,指出了今后的研究方向:探索最佳萃取pH值、提高改性剂性能、与其它试剂协同萃钒、优化萃取前的提钒工序等,同时加强胺类萃取剂萃钒机制的探究,开发高效且适应范围广的新型胺类萃取剂。Abstract: 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.
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