The Extraction of Bivalent Transition Metals from Aqueous Chloride Solutions by Long-chain Alkyl Quaternary Ammonium Carboxylates

Abstract

Abstract The extraction of bivalent manganese, cobalt, nickel, and copper from aqueous chloride solutions by longchain alkyl quaternary ammonium carboxylates, prepared by combination of trioctylmethylammonium chloride (R3R′NCl) and carboxylic (octanoic, decanoic, and lauric) acids (R″COOH) in benzene, has been investigated under different conditions. The organic phases are examined by spectrophotometry and infrared spectral measurement. The mechanism of the extraction is discussed on the basis of the results obtained. The extraction efficiency follows the order Cu>Co\simeqNi>Mn, and the extraction process is expressed as M2+(aq)+2Cl−(aq)+3R3R′NR″COO(org)\ightleftarrows(R3R′N)[M(R″COO)3](org)+2R3R′NCl(org), in which M=Mn, Co, Ni, and Cu. The extracted species of bivalent manganese, cobalt, nickel, and copper exist as the complex (R3R′N)[M(R″COO)3] in an octahedral arrangement.