Separation methods of rhodium-iridium alloy

Separation methods of rhodium-iridium alloy:

(1) Acid dissolution Rhodium-iridium alloy is first crushed into fine particles and then placed in a mixed acid containing chloride (such as aqua regia). Iridium reacts with the chlorine in the aqua regia to form iridium tetrachloride (IrCl4), while rhodium forms rhodium trichloride (RhCl3). This process is usually carried out at a controlled temperature to improve the reaction efficiency.

(2) Selective precipitation Iridium or rhodium can be selectively precipitated by adjusting the pH of the solution or adding specific precipitants. For example, iridium can be precipitated as iridium hydroxide (Ir(OH)4) by adding sodium hydroxide, while rhodium remains in solution. After the iridium is removed, the rhodium in the solution can be precipitated by a reduction reaction.

(3) Reduction and purification Rhodium is reduced to metallic rhodium by a reducing agent (such as formic acid or hydrogen), and the solid rhodium is then removed by filtration. For further purification, the rhodium can be redissolved and reduced multiple times, or purified by electrolysis.