一元烷基磷（膦）酸对镅,钕,铕的萃取

测定了８种一元烷基磷（膦）酸（ＨＬ）在不同ｐＨ和不同萃取剂浓度下对示踪量三价镅、钕、铕的萃取分配比Ｄ。萃取剂包括２种二烷基磷酸（ＲＯ）２ＰＯＯＨ、５种烷基膦酸单烷基酯（ＲＯ）ＲＰＯＯＨ和１种二烷基次膦酸Ｒ２ＰＯＯＨ，其中Ｒ是正辛基、仲辛基或异辛基。由ｌｇＤ－ｐＨ和ｌｇＤ－ｌｇｃＨ２Ｌ２直线的斜率分析可知，这３种元素的萃取反应是相同的。计算了各萃取反应的表观平衡常数Ｋｅｘ。铕的被萃取能力最强，镅和钕的被萃取能力接近，在大多数情况下，镅稍低于钕。随着萃取剂分子中ＲＯ基团被Ｒ基团取代及正辛基被仲辛基或异辛基取代，萃取能力明显下降，分离因数βＥｕ／Ａｍ和βＮｄ／Ａｍ略呈上升趋势。

THE EXTRACTION OF Am,Nd AND Eu BY MONOFUNCTIONAL ALKYL PHOSPHORIC, PHOSPHONIC AND PHOSPHINIC ACIDS

The extraction of americium,neodynium and europium by eight monofunctional alkyl phosphoric,phosphonic and phosphonic acids (HL) are measured under different pH and extractant concentrations.These extractants are two dialkyl phosphoric acids (RO) 2POOH,five alkyl phosphonic acid monoalkyl esters (RO)RPOOH,and one dialkyl phosphinic acid R 2POOH in which R is n octyl, s octyl or i octyl group.The slope analysis of lg D pH and lg D lg c H 2L 2 straight lines shows the same extraction mechanism of these three elements.The apparent equilibrium constants of extraction reactions K ex are calculated.The extractablility of europium is the strongest,while that of amercium and neodynium are close to each other and the former is slightly lower than the latter in most cases.The extraction power of the extractants decreases apparently with the replacement of RO group by R group and the replacement of n octyl group by s octyl or iso octyl group along with the slight increase of separation factors.