Chromatography of metal ions with thioglycolate chelating resin

Abstract

The synthesis and properties of a chelating resin containing a thioglycoloyloxymethyl functional group are described. This resin retains silver( I ) , bismuth( 111), tin( I V ) , antimony(III), mercury( 11), and gold( 111) from 0.1 M acid and cadmium( 11), lead(II), and uranium(V1) from pH 3.5 solution. On a column containing this resin, separations of several of these metal ions are obtained by elution with acetate and hydrochloric acid eluents. Application to real samples is demonstrated by the successful analysis of NBS samples for antimony, and of acidic brine solutions for traces of mercury( 11).Recent work has shown that chelating ion-exchange resins can be synthesized that are highly selective for certain groups of metal ions (1-4). The resins can be used to concentrate certain metal ions from aqueous solution and for columnchromatographic separations. The hexylthioglycolate resin developed by Moyers and Fritz ( 1 ) has been shown to be specific for silver(I), mercury(II), bismuth(III), and gold(II1) in 0.1 M acid. This resin is a diester formed by stepwise reactions of l,&hexanediol and thioglycolic acid with a carboxylic acid group on XAD-4, a macroporous styrenedivinylbenzene copolymer. The synthesis involves several steps and the final resin contains unreacted carboxyl groups which impart general ion-exchange properties. Thus, the hexylthioglycolate resin exhibits strong selectivity toward metal ions only in highly acidic solutions. This paper reports the synthesis and analytical applications of a resin containing the thioglycoloyloxymethyl chelating group (-CH20CO-CH2SH) attached to the benzene ring of a polystyreneDVI3 resin. Synthesis of this resin is more direct than that of the hexylthioglycolate resin, and the new resin is useful both in strongly acidic and in less acidic aqueous solutions. We report the retention behavior of a number of cations in acetate buffers, and demonstrate the separation of zinc(II), cadmium(II), and lead(I1). In addition, the retention behavior of silver(I), bismuth(II1). mercury(II), tin(IV), and antimony(II1) in hydrochloric acid is described. The results are compared with those of Moyers and Fritz using the hexylthioglycolate resin. Analytical applications are demonstrated by analyzing NBS standards for antimony and a simulated chlor-alkali brine for mercury(I1) using liquid chromatography with automatic detection. EXPERIMENTALLiquid Chromatograph. The system for liquid chromatography with automatic detection has been described previously ( 3 ) . Sample loops of 50, 200, or 1000 pL were used depending on the concentration of the ion of interest. A 10 cm by 2 mm i.d. column was used for the separation of zinc, cadmium, and lead and a 5 cm by 2 mm i.d. column was used for separations involving antimony, bismuth, and mercury. The resin used in these columns was taken from the <200 mesh fraction after grinding and sieving. It was slurried with methanol, allowed to settle, and the unsettled fines were decanted. This fractionation process was repeated several times after th...

Mechanism of heavy metal uptake by a hybrid MCM-41 material: Surface complexation and EPR spectroscopic study

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Selective ion exchange polymers

“…( I I I ) , @(II), C d ( I I ) , Pb(I1) and U(V1) were described by F r i t z and coworkers (41). Similar polymers f o r the c o l l e c t i o n o f heavy metals are dithiocarbmates and t h e i r derivatives.…”

Principais rotas de síntese de resinas complexantes de mercúrio

“…Também foram descritas duas rotas de síntese para a introdução de grupos tiol em resinas XAD-4 (copolímeros S-DVB com 10% de DVB) baseadas na reação desses suportes com ácido tioglicólico [68,69] . No primeiro trabalho, os suportes sofriam acilação Friedel-Crafts com anidrido acético, catalisada por cloreto de alumínio.…”