Solvent Extraction of Lanthanoid, Yttrium and Some Polyvalent Metal Ions with Phosphoric Acid Esters of Triton X-100

Polyoxyethylene chain-containing nonionic surfactant, Triton X-100 (decaethyleneglycol mono(4-(1, 1, 3, 3-tetramethylbutyl) phenyl)ether; ROH) was derived to phosphate mono-, di-, and tri-esters RH2PO4, R2HPO4 and R3PO4; abbreviated as MTP, DTP and TIP, respectively) and the metal extraction behavior of these phosphate esters was studied in 1, 2-dichloroethane-water system with particular emphasis on lanthanoid(III), yttrium(III), and some other polyvalent metal ions. The extraction was carried out at pH 2 in the presence (for TIP) or in the absence (for MTP and DTP) of picric acid. The metal extraction ability of these extractants followed the order of MTP> DTP>TTP under these extraction conditions. In the extraction by MTP and DTP, the extractability of lanthanoid ions increased with the increase in their atomic number. Mean separation factor of thirteen pairs of adjacent lanthanoids was evaluated to be 1.7 for MTP and 1.4 for DTP. On the other hand, the corresponding values for TTP was almost unity. None of these compounds practically extracted other polyvalent metal ions except iron ion. Iron- (III) ion was extracted with MTP and with DTP to a similar level to those of lanthanoid ions.