Abstract
The extraction of rhodium (III) from hydrochloric acid solutions has been investigated by using a trioctylmethylammonium chloride (TOMAC; R3R'NCl) under various conditions.
The extraction curve shows a minimum value at about 4 mol dm-3 in initial aqueous hydrochloric acid solution. The extraction efficiency is promoted in chlorobenzene, nitrobenzene and 1, 2-dichloroethane as diluent and suppressed in carbon tetrachloride and chloroform. At low acidity (≤4 mol dm-3HCl) both origomer bridged by hydroxyl group and chloro species are extracted, while at higher acidity (≥4 mol dm-3HCl) the origomer species is principally extracted. The stoichiometric composition of the origomer complex formed in the organic phase was found to be (R3R'N) 2Rh3 (OH) 4Cl7 (H20) 3.
The distribution ratio increases with increasing temperature.
In the examination of separation between rhodium (III) and ruthenium (III), the separation factor in the extraction of rhodium chloro species becomes about sixteen times greater than that from the solution containing origomer and chloro species.
