PRECONCENTRATION AND SEPARATION BY ELECTRODEPOSITION OF INDIUM FROM ITS DIFFERENT SOLUTION COMPLEXES

The use of electrodeposition for the isolation and preconcentration of indium from its different solution complexes is described. The cathodic deposition of indium was carried out at different pH values (1.5-13) using solutions containing indium(III) chloride with some complexing agents and with current density in the range 0.2-2 A/dm2. Emission spectroscopic (ICP-OAES); X-ray and chemical analyses revealed the purity of the indium deposited to be 99.8%. The effect of different parameters (pH, temperature, complexing agent/metal-ion ratio, current density, time and type of electrode) on the electrodeposition was studied. The current efficiency was calculated. The quantity and quality of indium deposited was found to depend on the type of bath used. The baths can be arranged in the following order: alizarin yellow > oxalic acid > thiourea > 1,10-phen > DMF > thiosemicarbazide > phenyl hydrazine > DMSO > PAN > 2(5-sulphophenyl azodihydroxynaphthalene > tetrahydroxy p-benzoquinone > 2,2-dipyridyl > adipic acid > methyl red > acetylacetoacetate > diphenyl sulphoxide > pyridine > NaI > NaBr = methyl violet > succinic acid > pyrogallol > NaCl > tartaric acid > gallic acid > alizarin > KNCS. A mechanism for the formation of indium has been proposed. An analytical application for the determination of indium in alumina ore, aluminium alloy and sea water has been described using preconcentration separation by electrodeposition.