title: On the stabilization of niobium(V) solutions by zirconium(IV) and hafnium(IV).
abstract: Niobium cannot be separated from zirconium or hafnium when these elements occur together in solution with common anions such as chloride and sulphate. This is ascribed to the co-polymerization of niobium(V) and the hydrolysed ionic species of zirconium(IV) and hafnium(IV) to form colloidal particles. In hydrochloric acid the particles are positively charged, whereas in sulphate solution the Zr-and Hf-sulphate complexes confer a negative charge. The two cases are considered separately.
authors.affiliation: Risø National Laboratory, Roskilde, Denmark.
authors.forename: E
authors.initials: E
authors.lastname: Sørensen
authors.forename: A B
authors.initials: AB
authors.lastname: Bjerre