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 is investigated 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 are investigated. The
synergistic effect showed that addition of D2EHPA to TOP (Tri-iso-octyl-phosphate) extraction was obtained for the volume ratio 4.5/0.5.
The thermodynamic functions like free energy (G), enthalpy (H) and entropy (S) of extraction mechanism are discussed. Solid phase
extraction is 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-1; for the liquid-solid extraction by Chelex 100 resin the removed quantity was 19 mg g-1. The stripping efficiency
was found to be quantitative in HNO3 and HCl 1 M. The robustness of the procedure is demonstrated by the average recoveries obtained
(>99.6 %) for samarium(III).
Key words: samarium(III); Chelex 100; D2EHPA; optimization; solid phase extraction; liquid–liquid extraction; rare earth elements.
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