Synthetic inorganic ion-exchange materials. Part XLIX. Adsorption and desorption behaviour of heavy metal ions on hydrated titanium dioxide

Abstract

The ion-exchange selectivity of a number of divalent metal ions was studied as a function of pH in nitrate and chloride media. The order of selectivity was Pb²⁺ > Hg²⁺ > Cd²⁺ > Mg²⁺ in nitrate solution and Pb²⁺ > Cd²⁺ > Ca²⁺ > Mg²⁺ > Hg²⁺ in chloride solution. A good linear relationship between the logarithm of the distribution coefficient of the heavy metal ions and their effective ionic radius was found. On the basis of the K_d values, the separation of a mixture of Cd²⁺, Hg²⁺ and Pb²⁺ and the group separation of Hg²⁺ and Pb²⁺ from several common metal ions were achieved on an ion-exchange column containing amorphous hydrated titanium dioxide.