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研究了由过氯酸盐水溶液与含某种β-二酮的四氯化碳溶液组成的溶剂萃取体系中铈的萃取与反萃取。由于萃取的螯合物中的铈(Ⅲ)易受空气中氧的氧化,所以延长两相搅拌时间可提高铈(Ⅲ)的萃取率。即使将有机相与水相分开,仍发现该整合物中的铈(Ⅲ)会发生这种氧化现象。对于不同的β-二酮螯合物,其铈(Ⅲ)的氧化速率大不相同。当所生成的这种金属螯合物与有机相中的三辛基氧膦(TCPO)形成加成物时,则其氧化速率要低得多。四氯化碳中β-二酮铈(Ⅳ)螯合物的反萃取速率与水相中的氢离子浓度及β-二酮浓度有关。由此可以断定,反萃取的控制反应应是水相中铈(Ⅳ)的还原反应。
The extraction and back-extraction of cerium from a solvent extraction system consisting of perchlorate aqueous solution and a carbon tetrachloride solution containing a certain β-diketone were studied. Since cerium (III) in the extracted chelates is easily oxidized by oxygen in the air, extending the two-phase stirring time can increase the extraction rate of cerium (III). Even if the organic phase is separated from the aqueous phase, it is found that the oxidation of cerium (III) in the complex occurs. For different β-diketone chelates, the oxidation rate of cerium (III) is quite different. When the resulting metal chelate forms an adduct with trioctylphosphine oxide (TCPO) in the organic phase, the oxidation rate is much lower. The rate of stripping of the β-dione cerium (Ⅳ) chelate in carbon tetrachloride is related to the hydrogen ion concentration in the aqueous phase and the concentration of β-diketone. From this we can conclude that the control reaction of stripping should be the reduction of cerium (IV) in the aqueous phase.