Separation of metals by a simultaneous extraction and back-extraction method with Teflon phase separator

研究了一种类似液膜法的同时提取、反提取和反提取的新方法，该方法采用两容器和特氟龙相分离器。用流动池分光光度计测定萃取金属配合物的吸光度。由于PAN[1-（2-吡啶偶氮）-2-萘酚]具有较高的灵敏度，因此被用作离子载体。考察了铁（II）、钴（II）和镍（II）在高速搅拌（2500rpm）下的分离和测定条件。铁钴配合物萃取至氯仿相后，立即用6M HNO_3溶液反萃取铁配合物。钴络合物保持在有机相中。在pH值为4的条件下，采用传统的萃取方法（采用分离漏斗），在40分钟后提取部分镍- pan，尽管络合物形成反应缓慢。用本方法将含铁络合物的过量试剂（PAN）反萃取到6 M HNO_3溶液中。镍- pan配合物的萃取率随萃取时间的延长而降低。因此，用本方法不能在pH为4时将镍配合物提取到氯仿中。

A new method, which is similar to a liquid membrane method, was inve stigated for simultaneous extraction and back-extraction and back-extrac tion using two vessels with Teflon phase separators. The absorbance of metal complexes extracted was measured by a spectrophotometor with a flow cell. PAN [1- (2-pyridylazo) -2-naphthol] was used as a ionophore because of its high sensitivity. The condition for the separation and the determination of iron (II) , cobalt (II) and nickel (II) were examined under high speed stirring (2500rpm). After extraction of iron and cobalt complex to the chloroform phase, iron complex was back-extracted woth 6M HNO_3 solution immediately. The cobalt complex remained in the organic phase. Nickel-PAN was partially extracted at pH 4 after 40 min by a conventional extraction-procedure, which used a separatory funnel, in spite of the slow complex formation reaction.By the present method, the excess reagent (PAN) with iron complex was back-extracted into 6 M HNO_3 solution. The extraction rate for the nickel-PAN complex decreased with the extraction time.Consequently, the nickel-complex was not extracted at pH 4 into the chloroform by the present method.