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-(2,4,4-trimethylpentyl) phosphinic acid, denoted HL) was prepared by adsorption of the organophosph orus extractant into the polymeric macroporous support Amberlite XAD-2. The extraction of Cr(III) from nitrate solution at 0.1 ionic strength by the i mpregnated resin has been studied at 25 degrees C. The sorption of the meta l ion was studied as a function of both pH and extractant concentration in the resin phase. The impregnated resin shows good affinity towards the extr action of Cr(III). The best sorption efficiency (98%) was obtained at pH ap proximate to 5. A thermodynamic model is proposed for modeling the distribu tion data. This model shows that Cr(III) is extracted as Cr(OH)(HL)(2)(NO3) (2) and Cr(OH)L-2. The elution of the metal from the resin was accomplished (95%) with 6.0 M HCl. The elution treatment allows the impregnated resin t o be reused.