Sorption of 46Sc3+ by iron(III) hydroxide and oxide under conditions of hydrolysis and complexation. I. Sorption under conditions of hydrolysis and carbonate complex formation

The sorption of 46Sc3+ by Fe(III)OH and α-Fe2O3 in 1 M NaNO3 is studied. The sorption of 46Sc3+ beings in the pH range of hydroxo-complex formation, Sc(OH)n3-n and increases with increasing pH. The relative amount of sorption remains constant at a given concentration of 46Sc3+. In basic media, the sorption decreases to zero as a result of formation of Sc(OH)4-, for which β4 is found. The sorption curves shift to the lower pH region in the range of hydrolysis of cationic Sc3+ upon increasing the mass of sorbent. In the presence of carbonate ions, the sorption of 46Sc3+ decreases and stops as a result of formation of Sc(CO3)33-. β3 for this complex is calculated from sorption data. The concentration of very small quantities of Sc3+ by sorption on Fe(III)OH in solutions of NaNO3 and the separation from sorbent upon re-precipitation of Fe(III)OH in Na2CO3 are studied. The sorption of 46Sc3+ by Fe(III)OH and α-Fe2O3 is explained by the coordinative interaction of Sc3+ hydroxo-complexes with the surface of the sorbent and formation of hydroxo (oxo-) bridges