Department of Materials Science, Graduate School of Engineering Science, Akita University, 1-1 Tegatagakuen-machi, Akita-shi, Akita, 010-8502, Japan.
Department of Earth Resource Engineering and Environmental Science, Graduate School of International Resource Science, Akita University, 1-1 Tegatagakuen-machi, Akita-shi, Akita, 010-8502, Japan.
Sci Rep. 2019 Aug 27;9(1):12414. doi: 10.1038/s41598-019-48920-9.
Although Rh is an industrially important and the most expensive platinum group metal (PGM), the selective and preferential separation of Rh from PGM mixtures still remains as a big challenge. In this work, the separation of Rh (III) from Pd (II) and Pt (IV) in a hydrochloric acid (HCl) solution was studied using a m-phenylene diamine-containing precipitant (m-PDA). At high HCl concentrations (6.0-8.0 M), most of the Rh (III) (>90%) was precipitated, and Pd (II) and Pt (IV) were hardly precipitated (<5%). On the other hand, over 85% of Pd (II) and Pt (IV) precipitated along with small amount of Rh (III) (<25%) at low HCl concentrations (1.0-2.0 M). As a consequence, m-PDA enabled selective and preferential precipitation of Rh (III) at high HCl concentrations. XPS and TG analyses revealed that the Rh-containing precipitate is an ion-pair complex composed of one [RhCl] anion and three m-PDA cations. The Rh desorption from the precipitate as well as the recovery of m-PDA was successfully achieved using an NHOH solution. This method is a promising practical approach to Rh recovery.
尽管铑是一种工业上重要且最昂贵的铂族金属（PGM），但从 PGM 混合物中选择性和优先分离铑仍然是一个巨大的挑战。在这项工作中，使用含有间苯二胺的沉淀剂（m-PDA）研究了在盐酸（HCl）溶液中 Rh（III）从 Pd（II）和 Pt（IV）的分离。在高 HCl 浓度（6.0-8.0 M）下，大部分 Rh（III）（>90%）被沉淀，而 Pd（II）和 Pt（IV）几乎不沉淀（<5%）。另一方面，在低 HCl 浓度（1.0-2.0 M）下，超过 85%的 Pd（II）和 Pt（IV）与少量 Rh（III）（<25%）一起沉淀。因此，m-PDA 能够在高 HCl 浓度下选择性和优先沉淀 Rh（III）。XPS 和 TG 分析表明，含 Rh 的沉淀物是由一个 [RhCl]阴离子和三个 m-PDA 阳离子组成的离子对复合物。使用 NHOH 溶液成功地实现了 Rh 从沉淀物中的解吸以及 m-PDA 的回收。该方法是一种有前途的实际回收 Rh 的方法。
