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胺类可从近于中性的水溶液中按溶剂化历程主要靠 H—键形成分子缔合物萃取Cr(Ⅵ),Mo(Ⅵ),W(Ⅵ),V(Ⅴ)等金属.根据与氮相连结的活性氢原子的多寡与有无,讨论了伯、仲、叔胺类溶剂化能力的强弱.伯胺分子中含有两个活性氢原子,因此它的溶剂化能力高于仲胺和叔胺.本文所研究的溶剂化历程与一般使用胺盐萃取的离子交换历程其规律完全不同.水溶液中过渡元素含氧酸阴离子在不同的平衡 pH 下具有不同聚合形态.本文根据电荷密度及比电荷概念预测其疏水性,并阐明了不同元素在相同条件下及相同元素在不同条件下可萃倾向不同的原因.实验证实了这种预测,并为金属的萃取和分离开辟了新的研究领域.

Metals such as Cr(Ⅵ),Mo(Ⅵ),W(Ⅵ) and V(Ⅴ) can be extracted by am- ines from nearly neutral aqueous solutions.The mechanism of extraction has found to be by solvation with molecular association through hydrogen bonds.The number of active hydrogen atoms attached to nitrogen atom of different classes of amine determine their effectiveness in extraction of metals by solvation.Primary am- ines with two hydrogen atoms attached to each nitrogen atom are the most effec- tive extractants in comparison with secondary and tertiary amines.Results obtained from metals extraction with amines by the present reported solvation mechanism are quite different from those obtained by the widely studied anion exchange mechanism. The oxo and hydroxo complexes of transition metals such as Cr,Mo,W and V in aqueous solutions form different types of isopolyanion at different solution pH.The electric charge density or specific charge of different isopolyanions can be used to predict the relative tendency of these species to be extracted by the amines through solvation mechanism.Experimental results confirm the prediction and indicate that by using amines as solvation extractant new processes can be developed for metal extraction and separation.