Solvent Extraction of Precious Metals with an Organoaminophosphonate

ABSTRACT

p-(l,l,3,3-Tetramethylbutyl)phenyl hydrogen[N,N-di(2-ethylhexyl)amino-methylphosphonate was synthesized as a novel type of extractant to investigate the extraction behavior of base metals as well as of precious metals from aqueous chloride media into toluene. This reagent exhibited high selectivity for platinum (IV) and palladium (II) ions in the low acidic region (0·01 - 6 mol dm⁻³) / over base metal ions except for trivalent iron over the whole concentration region under the present experimental conditions. The extraction of platinum and palladium with p-( 1,1,3,3-tetramethylbutyl)phenyl hydrogen[N,N-di(2-ethylhexyl)aminomethyl-phosphonate was higher than that with N,N-di(2-ethylhexyl)aminomethyl-phosphonic acid due to its high lipophilicity. Stripping of the loaded palladium was achieved with an aqueous mixture of I mol dm⁻³ thiourea in combination with I mol dm⁻³ hydrochloric acid. The extraction reaction of palladium from aqueous chloride media into toluene was found by slope analysis to be described as follows

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Notes on contributors

Yoshinari Baba

The present adress: Department of Material Science, Faculty of Engineering, Miyazaki University, Gakuenkibanadai Nishi, Miyazaki 889-21, Japan)