Octafunctionalized calix[4]resorcinarene-N-fenil-acetohydroxamic acid for the separation, preconcentration and transport studies of cerium(IV)

A new method for liquid-liquid extraction, separation and preconcentration of cerium(IV) with a calix[4] resorcinarene acid derivative [C4RAHA] is reported. Cerium was extracted at pH 9 in ethyl acetate and recovered from monazite sands in the presence of thorium, uranium, lanthanum and large number of cations and anions. Cerium(IV) forms yellow coloured complex, lambda(max) 381 nm, molar absorptivity 1.06 x 10(4) L mol(-1)cm(-1) and obeys Beer's law over the range 0.4-15 mg mL(-1). The metal ligand ratio for cerium (IV) was found to be 4:1 (M:L). Transport studies were carried out in a three phase system across a liquid membrane containing C4RAHA. For ICP OES measurements, the extract can be directly aspirated, which enhances the sensitivity 25-fold and the limits for estimation are 5-150 mu g L-1 of cerium. The method was applied for the determination of cerium in standard geological samples, monazite sand and sea water samples.