| The removal and recovery of gallium (III) from aqueous solutions was investigated using different ligands. Sodium di-(n-octyl) phosphinate was found to be the most effective ligand. The metal-ligand complexes formed had the advantages of being highly insoluble in water and allowing a good regeneration of the ligand at the end of the cycle. The effect of time, pH, mole ratio of ligand to metal, temperature and the presence of other ions, such as Na+, NO3-, Cl- and SO42-, was also studied. At the end of the removal process, gallium was recovered from the insoluble complexes using a solvent. The gallium was concentrated in an aqueous phase. The ligand was extracted in the organic phase and regenerated. Other organophosphorus ligands such as sodium di-(n-dodecyl) phosphinate, sodium mono-octyl ester phosphinate and O,O-di-(octyl) dithiophosphoric acid were also synthesised and studied. They were less efficient for the removal of gallium than the sodium di-(n-octyl) phosphinate ligand. The possibility of using compounds with a carboxylic group on the removal of gallium was also investigated using humic and fumaric acids.; The removal with sodium di-(n-octyl) phosphinate of other metals such as aluminum, indium, iron, calcium and zinc, found in the mining and electronic effluents with gallium, was considered. A good selectivity of the ligand for the gallium over the other metals was obtained. A process was proposed for the electronics industry to treat gallium arsenic effluent.; Finally a mathematical model was established to describe the removal behavior of the metals with the sodium di-(n-octyl) phosphinate ligand. |
