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

Vinod K Jain,Shibu G Pillai,Parin H Kanaiya

doi:10.1590/s0103-50532006000700018

Abstract

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, lambdamax 381 nm, molar absorptivity 1.06 <FONT FACE=Symbol>´</FONT> 10(4) L mol-1cm-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 µg L-1 of cerium. The method was applied for the determination of cerium in standard geological samples, monazite sand and sea water samples.

Highlights

The chemistry of bowl shaped macrocyclic compounds that can complex organic and inorganic guests has been receiving significant attention in the field of supramolecular chemistry.[1]
Cerium is the major element present in monazite sands associated with lanthanum, thorium and uranium
A large number of reagents have been reported for the separation of cerium, several closely related ions including thorium and traces of uranium interfere.[20,21,22,23,24]

Summary

Introduction

The chemistry of bowl shaped macrocyclic compounds that can complex organic and inorganic guests has been receiving significant attention in the field of supramolecular chemistry.[1]. In the present study we have used Calix[4]resorcinarene-Nfenil-acetohydroxamic acid (C4RAHA) for the liquid-liquid extraction, preconcentration and transport of cerium across a liquid membrane. To check the applicability of the proposed method, cerium was determined in monazite sand, standard geological materials and sea water samples. × 10-5 mol L-1 solution was prepared in ethyl acetate.

Results

Conclusion