Sorption Mechanism of Metal Ions on the Salts of Heteropoly Acids

Published data on the sorption properties of insoluble salts of heteropoly acids (HPA) are discussed in terms of recent views on the structure of HPA salts and on the tendency of ions to form heteropoly compounds, and a classification of ions which can be sorbed on HPA salts is proposed. The special features of the sorption mechanism of specific groups of ions are discussed, and sorption on HPA salts is shown to be a complex process, influenced by properties of the ions such as radius, ionic potential, state of the ion in solution, and tendency to form complexes. The sorption of ions which can form heteropoly compounds is a multi-step process, accompanied by interaction of the sorbed ions with the molybdophosphate anion.
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