EXTRACTION OF METAL-OXALATE COMPLEXES BY DICATIONIC ANION-EXCHANGE EXTRACTANTS

ABSTRACT The extraction of oxalate complexes of divalent metal ions (Zn2+, Cd2+ ) by dicationic anion-exchange extractants, polymethylenebis(trioctylphosphonium)s (abbreviated as CnBP), was studied. The shorter the length of methylene-chain connecting two cationic centers within an extractant molecule, the higher was the extractant capability, i. e., the extraction ability of extractants decreased in the order: C2- > C3- > C4- > C5- > C6- > C8- > C10- > C12BP. The entirely inverse order was obtained in the extraction of metal-halide complexes (MIICl4 2-) and metal-cyanide complexes (M II(CN) 4 2-). The extraction abilities of monocationic extractants were inferior to even that of the least efficient one among the dicationic extractants. The extraction equilibrium was also studied.