Construction of Recovery and Recycling System for Rare Metals by Centrifugal Partition Separation Method

采用溶剂萃取法和高效离心色谱法对金属的化学处理和回收进行了基础研究。本调查的目的是建立一个程序，废物可以减少，并促进再使用的产品制造。此外，认为通过我们的调查可以进行环境保护和有效利用自然资源。首先，我们以0.16 M双-2-乙基己基膦酸在庚烷（BEHPA）中作为固定相，研究了HPCPC对碱土金属离子的相互分离。用氯乙酸流动相（pH 6.5和5.3）两步洗脱负载的四种金属离子。在pH 6.5的流动相中加入5%乙醇，分离Sr（II）和Ba（II）。色谱条件为2136个分区通道，转速800 rpm，流速1.5 ml/min。用显色剂对每个金属配合物的吸光度进行监测，得到了洗脱曲线。以二-2-甲基壬基磷酸/庚烷为固定相，研究了HPCPC对Cu（II）、Mn（II）、Co（II）、Ni（II）等金属离子的分离。四种过渡金属离子通过两步洗脱法相互分离，改变氯乙酸酸流动相的pH。流速2.0 ml/min。以0.16 M BEHPA/heptane为固定相，采用两步法分离Fe（III）、Zn（II）、Mn（II）、Co（II）和Ni（II）等过渡金属离子。乙酸、氯乙酸和酒石酸缓冲液为流动相。用泵将Co(II)-Ni（II）混合溶液连续输送到固定相时，发现Co（II）在Co(II)-Ni（II）混合溶液中存在选择性保留。因此，采用本方法提纯镍（II）溶液将在镍电池工业领域得到应用。对轻、中稀土金属离子进行了HPCPC分离试验。从萃取研究中可以预见，在常规流速下，HPCPC分离这些金属是相当困难的。我们尝试以0.2 ml/min的慢速流速分离它们。La(III)-Ce(III)-Pr（III）、Eu(III)-Sm（III）和Gd(III)-Tb(III)-Dy（III）混合物分别在pH为2.95、2.30和1.55时相互分离。从以上结果可以看出，HPCPC方法对于实验室尺度上研究的金属离子的分离是非常有用的。沉淀、离子交换、膜过滤分离等可结合HPCPC进行实际和化学处理，作为下一步研究的金属回收和再循环过程。正在进行进一步的研究，以建立废物和水中金属的回收和再循环系统。少

The fundamental studies on chemical treatment and recycling of metals have been undeftaken by solvent extraction and high performance centrifugal partition chromatography (HPCPC). The aim of this investigation is to establish the procedure that the waste materials can be reduced and be promoted to reuse for manufacturing of products. Furthermore, it is considered that environmental protection and efficient use of natural resources can be performed through our investigations.First, we have investigated the mutual separation of alkaline earth metal ions by HPCPC using 0.16 M bis-2-ethylhexylphosphinic acid in heptane (BEHPA) as a stationary phase. Two-step elution of the four metal ions loaded was accomplished with aqueous chloroacctic acid mobile phase (pH 6.5 and 5.3). Ethanol (5%) was added to the pH 6.5 mobile phase for the separation of Sr(II) and Ba(II). The chromatographic conditions were 2,136 partition channels, 800 rpm rotation speed, and 1.5 ml/min flow rate. The elution curve … More was obtained by monitoring the absorbance of each metal complex post-tabled with a chromogenetic agent.The separation of such metal ions as Cu(II), Mn(II), Co(II) and Ni(II) has been investigated by HPCPC employing di-2-methylnonylphosphoric acid/heptane as a stationary phase. The four transition metal ions have mutually been separated by the two-step elution method, changing the pH of the chloroacetic acid acid mobile phase. The flow rate was 2.0 ml/min.Such transition metal ions as Fe(III), Zn(II), Mn(II), Co(II) and Ni(II) can be separated by the two-step HPCPC method using 0.16 M BEHPA/heptane as a stationary phase. Acetate, chloroacetate and tartrate buffers were used as mobile phases. The coexisting Co(II) in a mixed Co(II)-Ni(II) solution was found to be selectively retained when the sample solution was continuously delivered into the stationary phase by a pump. Thus, the purification of Ni(II) solution by the present HPCPC method would be applied in the field of nickel battery industry.The light and middle rare earth metal ions were attempted for HPCPC separation. It can be expected from extraction studies with BEHPA that the HPCPC separation of these metals is rather difficult at a conventional flow rate. We have tried to separate them at a slower flow rate of 0.2 ml/min. La(III)-Ce(III)-Pr(III), Eu(III)-Sm(III) and Gd(III)-Tb(III)-Dy(III) mixtures were mutually separated at pH 2.95, 2.30 and 1.55, respectively.From the above results, it was found that the HPCPC method was very useful for the separation of metal ions investigated at a laboratory scale. Precipitation, ion exchange, membrane filter separation can be combined with HPCPC for actual and chemical treatments for recovery and recycling process of metals as the next step of investigation. Further studies are in progress to construct the system of recovery and recycling of metals in waste materials and waters. Less