title: Selective removal of gallium (III) from aqueous solutions containing zinc or aluminum using sodium di-(n-octyl) phosphinate.
abstract: Gallium was removed selectively from aqueous solutions containing zinc or aluminum using sodium di-(n-octyl) phosphinate as a ligand (NaL). At low pH or low mole ratios, the gallium was removed by complexation with the ligand as GaL(3(S)), while the zinc or the aluminum remained in the solution. Nearly complete separation of gallium was obtained. By increasing the amount of ligand or by increasing the pH, the zinc or aluminum remaining in the solution was then removed as a solid complex: ZnL(2(S)) or AlL(3(S)), respectively. At a pH between 1.5 and 2 and a mole ratio ligand to total metals of 0.75 for zinc solutions and 1.0 for aluminum solutions, more than 98% of the gallium was selectively removed with a high molar selectivity, alpha(Ga/Zn) and alpha(Ga/Al), respectively. Over 95% of gallium was recovered from the solid GaL(3(S)) complex by treatment of the complex with a 3M NaOH solution and diethyl ether. The gallium was concentrated in the aqueous solution to 4 times its initial concentration and the ligand was extracted into the ether phase. After evaporation of the ether, 95% of the ligand was regenerated in its sodium form as a solid.
authors.affiliation: Department of Chemical Engineering, McGill University, 3610 University Street, Wong Building, Montreal, Quebec, Canada, H3A 2B2.
authors.forename: Rémy
authors.initials: R
authors.lastname: Dumortier
authors.forename: Eva
authors.initials: E
authors.lastname: Rodil
authors.forename: Martin E
authors.initials: ME
authors.lastname: Weber
authors.forename: Juan H
authors.initials: JH
authors.lastname: Vera
mesh_terms: D000535:Aluminum / Q000737:chemistry*; D005708:Gallium / Q000302:isolation & purification*; D006863:Hydrogen-Ion Concentration; D008024:Ligands; D010721:Phosphinic Acids / Q000737:chemistry*; D012995:Solubility; D018508:Water Purification / Q000379:methods*; D015032:Zinc / Q000737:chemistry*
chemical_list: D008024:Ligands; D010721:Phosphinic Acids; C488214:sodium di-(n-octyl)phosphinate; D005708:Gallium; D000535:Aluminum; D015032:Zinc