Selective extraction of one or more metal anions from an aqueous solution,
by contacting the aqueous solution with an organic solution including a diquaternary
amine, wherein the diquaternary amine has two diquaternary nitrogens spaced at
a distance of less than about 10 , selectively binding the metal anions
to the diquaternary amine, and then separating the organic solution from the aqueous
solution, wherein the diquaternary amines having the selectively bound metal anions
are concentrated in the organic solution. Alternatively, the diquaternary amines
may be adsorbed or chemically bonded to a solid, and the metal anion-containing
aqueous solution passed over the solid having the diquaternary amines. Palladium
may be selectively extracted by contacting the acidic solution with an iodide and
an organic solvent, allowing the palladium to bind to the iodide, and then separating
the organic solution from the aqueous solution, concentrating the bound palladium
ions in the organic solution.
