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磷酸三丁酯(简称TBP)能很好的从硝酸溶液中萃取希土元素硝酸盐。Peppard等指出,在萃取时若加入他种硝酸盐【如Al(NO_3)_3等]作为盐析剂,可大为提高希土元素的萃取率。随后McKay等报导以硝酸纳作盐析剂时,希土元素的分配系数反随酸度降低而增加。他们并指出在低酸度及高盐析剂浓度下,也能使希土元素得到较好的分离。Rydberg等以Ca(NO_3)_2作盐析剂,在萃取镧时亦得到类似的结果。为研究在不同酸度特别是高酸度下,盐析剂对萃取分离希土的影响,我们选择硝酸铵作为盐析剂,对镨、钕和钐硝酸盐的萃取进行研究。
Tributyl phosphate (referred to as TBP) can be well extracted from the nitric acid solution of rare earth elements nitrate. Peppard et al. Pointed out that the addition of other nitrates such as Al (NO 3) 3 as the salting-out agent can greatly improve the extraction rate of rare earth elements. McKay et al. Reported subsequently that with nitrate as a salting-out agent, the partition coefficient of the rare earth element increases inversely with decreasing acidity. They also point out that at low acidity and high salinitiator concentrations, it is also possible to achieve a better separation of the rare earth elements. Rydberg et al. Used Ca (NO 3) 2 as a salting-out agent, and obtained similar results when extracting lanthanum. In order to study the effect of salting-out agent on extraction and separation of rare earth under different acidity, especially high acidity, we chose ammonium nitrate as salting-out agent to study the extraction of praseodymium, neodymium and samarium nitrate.