STUDY OF THE SORPTION OF Cr(III) WITH XAD-2 RESIN IMPREGNATED WITH DI-(2,4,4-TRIMETHYLPENTYL)PHOSPHINIC ACID (CYANEX 272)

Solvent impregnated resin containing Cyanex 272 (di-(2,4,4trimethylpentyl)phosphinic acid, denoted HL) was prepared by adsorption of the organophosphorus extractant into the polymeric macroporous support Amberlite XAD-2. The extraction of Cr(III) from nitrate solution at 0.1 ionic strength by the impregnated resin has been studied at 25°C. The sorption of the metal ion was studied as a function of both pH and extractant concentration in the resin phase. The impregnated resin shows good affinity towards the extraction of Cr(III). The best sorption efficiency (98%) was obtained at pH=5. A thermodynamic model is proposed for modeling the distribution data. This model shows that Cr(III) is extracted as Cr(OH)(HL)2(NO3)2 and Cr(OH)L2. The elution of the metal from the resin was accomplished (95%) with 6.0 M HCl. The elution treatment allows the impregnated resin to be reused.