| 摘要 |
PROBLEM TO BE SOLVED: To efficiently extract palladium with high selectivity by preparing an extraction agent containing caffeine as an active component in order to selectively extract palladium from an acidic aqueous hydrochloric acid solution containing at least the palladium as a metallic ion. SOLUTION: In order to selectively extract palladium from an acidic aqueous hydrochloric acid solution containing at least the palladium as a metallic ion, an extraction agent containing caffeine as a useful component is prepared. Thus even when the palladium happens to be present in a series in which a base metal and/or any other precious metal coexist, the palladium can be efficiently extracted from the series with high selectively. When the palladium is extracted and recovered using this kind of extraction agent, an extraction solvent containing the caffeine as a selective extraction agent for the palladium is brought into contact, in the liquid-liquid contact mode, with the acidic aqueous hydrochloric acid solution containing at least the palladium as a metallic ion and thereby, the palladium is extracted in the extraction solvent.
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