P538萃取法从铂、钯、铑和铱混合物中纯化铑的研究

A STUDY ON THE PURIFICATION OF Rh BY EXTRACTION WITH P538FROM MIXTURES CONTAINING Pt,Pd,Rh AND Ir

提出了从 Pt,Pd,Rh 和 Ir 的混合物中纯化 Rh 的 P萃取法.首先将 Rh(Ⅲ)转化为水合阳离子,然后用 P的煤油溶液将其萃取到有机相,仍处于阴离子状态的 Pt,Pd 和 Ir 则留在水相.一次萃取 Rh 的直收率可达95%以上,Pt,Pd 和 Ir 的萃取率在1%以下.

A solvent extraction process for the purification of Rh from mixtures containing Pt,Pd,Rh and Ir has been developed.The mixtures were first boiled with HCl to convert polynuclear complexes to monomeric.Ir(Ⅳ)was reduced to Ir(Ⅲ)with hydroquinone after cooling.The pH was brought to 11~12 with NaOH.The solutions were maintained at this pH and 35℃for 30 min,and then acidified to pH 1.2~1.5 with HCl.Chlorine was passed though the solutions to restore Ir(Ⅲ)to Ir(Ⅳ).The hydrated cationic Rh(Ⅲ)species thus Prepared were extracted to partially saponified P(a mixture of monoalkyl phosphates)-HDEHP-kerosine solutions in volume ratio of 2:5:15,while Pt,Pd and Ir were left in the aqueous phases as complex anionic species.Rh(Ⅲ)was finally back-extracted with 1~6M HCl.The experimental results showed that the direct recovery of Rh was higher than 95%and the amounts of Pt,Pd and Ir extracted were less than 1%for a single-stage extraction.