Anion-exchange behaviour of some metal ions in sodium nitrite-aqueous-organic media on amberlite M-500 exchanger

Abstract

Anion exchange distribution coefficient (<i>K_d</i>) has been measured for the partition of metal ions such as Th(lV), Co(ll), Ni(II), Zn(II), Pb(II) and-Ag(l) between Amberlite M-500 anion exchange resin and organic solvent-water mixtures containing NaNO₂ as the eluting agent. The effect of variation in concentration of organic solvents as well as nitrite solution of the <i>K</i>_d- values of these metal ions shows the importance of such media as complexing agents giving anionic complexes. The presence of an organic solvent causes metal ions to be taken up at lower as well as higher concentrations of sodium nitrite. The order of distribution coefficients in alcohol-water-nitrite media is, iso propyl > ethyl > methyl alcohol. In many cases, the <i>K_d </i> values are also markedly higher in acetone-water-nitrite media than those in aqueous-nitrite system. With the help of distribution data, some possible separation techniques are developed.