Optimized Rhodium Dissolution Process Using Aqua Regia

The present paper focuses on a unique, optimized process of completely dissolving rhodium that can be employed on a large scale. Dissolution of rhodium has always been a challenging aspect of rhodium metallurgy due to its poor solubility even in mineral acids under ordinary conditions. In this paper, we present a means of achieving complete dissolution of rhodium powder in aqua regia using an experimentally optimized set of process parameters including solvent volume, temperature and heating time. The result is a solution in which the rhodium is completely dissolved which is confirmed by using optical microscopy at 50x magnification. Further, through the outcome of the experiments, it is concluded that it is possible to qualitatively ascertain the extent of rhodium content in the powder by observing the color of the solution. Comparison is also carried out with results obtained from dissolution experiments employing non-optimized process parameters in aqua regia as solvent.