SAMARIUM (III) REMOVAL BY LIQUID–LIQUID AND SOLID-PHASE EXTRACTION. KINETICS AND THERMODYNAMICS ASPECTS

Abstract

The liquid–liquid and liquid-solid extractions of samarium (III) from aqueous nitrate solution using D2EHPA (di-2-ethylhexyl phosphoric acid) and chelating resin “Chelex 100” as extractants have been investigated in this paper in order to recover samarium (III) from aqueous solution. The effect of operating parameters, such as time, nitrate ion, aqueous phase acidity, concentration of the extractant, resin mass, ion strength, temperature on the samarium extraction and various acid solutions on the metal stripping from the loaded organic phase and resin were investigated. The synergistic effect showed that addition of D2EHPA to TOP extraction was obtained for the volume ratio 4.5/0.5. The various thermodynamic functions like free energy (DG), enthalpy (DH) and entropy (DS) of extraction mechanism were discussed. Solid phase extraction was found to be more suitable than the liquid–liquid extraction for samarium (III) recovery. By liquid-liquid extraction the removed quantity was 93.26 mg / g; for the liquid-solid extraction by chelex100 resin the removed quantity was 19 mg / g. The stripping efficiency was found to be quantitative in HNO 3 and HCl 1M. The robustness of the procedure was demonstrated by the average recoveries obtained (>99.6%) for samarium(III).