The extraction behavior of Lanthanoid elements has been investigated using such $-diketone derivatives (HA) as dodecylbenzoy trifluoroacetone (LIX 51), benzoy isooctanoylmethane (LIX 54) and dibenzoy methane (DBM) in kerosene. Trivalent Lanthanoid ions (M3+) were extracted as tris-l3-diketonate (MA3); the extraction tendency followed the sequence LIX 51>LIX 54>DBM. The extraction constants (KeX) for lanthanoid elements increased with an increase in their atomic number, and a "tetrad effect" was

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... approximately observed for each extraction system. The mean separation factor between adjacent elements was evaluated to be 1.71 for LIX 51, 1.95 for LIX 54 and 2.23 for DBM.