Department of Materials Chemistry, Ryukoku University, Seta, Otsu 520-2194, Japan.
Innovative Materials and Processing Research Center, Ryukoku University, Seta, Otsu 520-2194, Japan.
Int J Mol Sci. 2020 Jul 17;21(14):5060. doi: 10.3390/ijms21145060.
There is increasing interest in the development of noble metal separation/recovery processes, especially for applications to "urban mining". Common separation/recovery processes for noble metals use a solvent (liquid-liquid) extraction technique in hydrometallurgy. However, these processes are time-consuming and not environmentally friendly, because they use organic solvents for sequential metal ion extractions. Electrowinning is an alternative approach for selective metal precipitation that involves controlling the redox potentials of electrodes but requires specialized equipment and generates hydrogen as a byproduct at the cathode surface under dilute conditions. In the present study, we investigated selective gold recovery from a homogenous aqueous solution containing a mixture of dilute HAuCl and HPtCl (5.0 × 10 M each) and aromatic amino acid-containing peptides (2.0 × 10 M each). Gold selectivity was determined by analyzing the compositions of the solids and supernatants obtained from the reaction mixtures. A much higher gold selectivity (gold/platinum (Au/Pt) atomic ratio = 7.5) was obtained using an anthracene-containing peptide compared to peptides containing one or two naphthalene ring(s). Our proposed approach is applicable to the sequential separation of several noble metal ions, such as Au, palladium (Pd), Pt, iridium (Ir) and rhodium (Rh), and simply requires developing aromatics suitable for each noble metal of interest.
人们对开发贵金属分离/回收工艺越来越感兴趣，特别是应用于“城市采矿”。常见的贵金属分离/回收工艺在湿法冶金中使用溶剂（液-液）萃取技术。然而，这些工艺耗时且不环保，因为它们使用有机溶剂进行连续的金属离子萃取。电积是一种替代方法，用于选择性金属沉淀，涉及控制电极的氧化还原电位，但需要专门的设备，并在稀溶液条件下在阴极表面产生氢气作为副产物。在本研究中，我们研究了从含有稀 HAuCl 和 HPtCl（各 5.0×10 M）和含芳香族氨基酸的肽（各 2.0×10 M）的均相水溶液中选择性回收金。通过分析从反应混合物中获得的固体和上清液的组成来确定金的选择性。与含有一个或两个萘环的肽相比，使用含蒽的肽可获得更高的金选择性（金/铂（Au/Pt）原子比=7.5）。我们提出的方法适用于几种贵金属离子（如 Au、钯（Pd）、Pt、铱（Ir）和铑（Rh））的顺序分离，只需开发适用于每种感兴趣的贵金属的芳烃即可。
