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The extractive separation of samarium(III) from nitrate solution by some phosphine oxide compounds, such as cyanex 921, 923 and 925 (El-Nadi et al., 2007) in kerosene was investigated. Separation of samarium(III) was carried out by using extractants 2-ethylhexylphosphonic acid, mono-2-ethylhexyl ester diluted in isododecane from gadolinium(III) in the monazite sand (Miranda and Zinner, 1997). A batch and continuous scale study has been carried out with phosphoric RG7204 (D2EHPA), phosphonic acid (IONQUEST 801) and a phosphinic acid (Cyanex 272) for the extractive separation of samarium from gadolinium (Benedetto et al., 1993). A distribution of trivalent samarium(III) between hydrochloric acid solution and solutions of di-(2-ethylhexyl)-phosphoric acid (DEHPA) or 2-ethylhexyl 2-ethylphosphonic acid (EHEHPA) in kerosene with 10 min shaking has been investigated (Sato, 1989). A batch process was developed to separate samarium from the monazite mineral of the Egyptian beach black sand deposits after cerium separation. The process was based on extraction by di-2-ethylhexyl phosphoric acid/kerosene from nitric–hydrochloric acid mixture (Rabie, 2007). However, in these methods, stripping requires many contacts with the organic phase for recovery of the metal. In general the extraction by phosphoric acid extractants was strongly affected by their extractability being insufficient and their low loading capacity for samarium(III) results from the low lipophilicity of coordination compounds formed during the extraction.