二(2-乙基己基)膦酸萃取Er(Ⅲ)的动力学和机理
KINETICS AND MECHANISM OF Er(Ⅲ) EXTRACTION FROM HYDROCHLORIC ACID SOLUTIONS WITH H(DEHP)
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摘要: <正> 一、引言 H(DEHP)是HEH(EHP)和HDEHP的同系物,它们的结构分别为:HDEHP,(GO)_2PO(OH);HEH(EHP),(GO)(G)PO(OH);H(DEHP),(G)_2PO(OH)。其中G为2-乙基已基。 希土元素萃取分离工艺化学表明,溶剂萃取希土元素对酸度的依赖关系及相邻希土元素间的分离因素值是选择萃取剂时应优先考虑的因素。HDEHP萃取剂对中、重希士元素反萃酸度高,HEH(EHP)是一个优良萃取剂,但对Er,Tm,Yb,Lu的反萃仍需5mol/l的酸。由于H(DEHP)分子中不含酯氧原子,使得它的pK_a值比HDEHP和HEH(EHP)的高。从而,用H(DEHP)萃取希土元素时需要的水相酸度更低,反萃更容易。而且H(DEHP)Abstract: The kinetics of extraction of Er(Ⅲ) from hydrochloric acid solutions with H(DEHP) in n-heptane is investigated using the growing drop technique. The rate is found to be first order with respect to Er(Ⅲ) and a half order with respect to H2A2(0). The rate controlling step is found to be the chemical reaction of Er(Ⅲ) with HA at the aqueous, organic interface. The activation energy for the extraction is calculated.
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