PURPOSE: To refine crude Pd to high purity at a good yield by dissolving the crude Pd with aqua regia under specific conditions, extracting the Pd with a water insoluble org. solvent and reverse extracting the Pd in the org. solvent with an aq. ammonium salt-contg. ammonia soln.
CONSTITUTION: The crude Pd is dissolved with the aqua regia to prepare the original liquid of ≤10mol concn. of chlorine ions (the lower limit is about 0.00000mol). This Pd-contg. original liquid is extracted with an extracting liquid consisting of dihexyl sulfide having ≥95% purity and the water insoluble org. solvent to extract the Pd in the org. phase. The Pd extracted in the org. phase is then reverse extracted by the aq. ammonia soln. contg. the ammonium salt (ammonium chloride, ammonium bromide, etc.) and hydrochloric acid is added to the aq. soln. in which the Pd is reverse extracted to settle Pd(NH3)2Cl2. The formed precipitate is filtered out in a short period and is successively cleaned by dilute hydrochloric acid and ethyl alcohol. The cleaned precipitate is dried and is calcined in air to form the metal Pd. The crude Pd is thus refined to the extremely high purity at the good yield by the relatively easy operation.
HIRAI MOTOYUKI
SUZUKI TETSUYOSHI
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