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Niobium Colloidal

Colloidal Niobium.—Sols of niobium have been prepared by sparking electrodes of the metal immersed in wobutyl alcohol by means of an induction coil,3 or by reducing solutions of niobium salts with hydrazine, formic acid or formaldehyde in the presence of gelatose.4... [Pg.135]

Hydrates of Niobium Pentoxide. Colloidal Niobium Pentoxide.— Niobium pentoxide does not combine directly with water to form acids of definite composition. Two hydrates of the oxide, namely, 3Nb20s.4H20 and 3Nb205.7H20, have been reported,8 but their existence is very improbable. The term nioUe acid, is applied to the more or less hydrated pentoxide. When niobium pentachloride or niobium oxytriehloride, NbOCla, is hydrolysed with excess of water there is produced a white, amorphous, hydrated gel, which can also be obtained by the action of sulphuric acid or hydrochloric acid on alkali niobates 10 the precipitate is redissolved by excess of acid. Similar solutions axe... [Pg.156]

Analytical Methods. The lack of stable niobium compounds resulting from a pronounced tendency for hydrolysis to colloidal suspensions of... [Pg.24]

In addition to dissolving in acids, freshly precipitated niobium pentoxide dissolves in caustic soda and in caustic potash, and hence it appears to possess weakly amphoteric character. Its colloidal state in solution has hitherto prevented any direct determination of its basicity or acidity. According to Weinland and Storz 6 it is comparable to silicic acid, and is more strongly acid than titanic add. That niobic add is a very weak add is shown by the readiness with which the niobates are (a) hydrolysed and (b) decomposed by mineral acids,... [Pg.157]

The predominant oxidation stale of the element is (V). There is some evidence that the (IV) state is obtained under certain reduction conditions. When the pentapositive form is not in the form of a complex ion it may exist in solution as PaC>2+. The compounds are very readily hydrolyzed in aqueous solution yielding aggregates of colloidal dimensions, thus showing marked similarity to niobium and tantalum in this respect. These properties play a dominant role in the chemical properties of aqueous solution, because the element is so easily removed from solution by hydrolysis and adsorption Protactinium coprecipilates with a wide variety of substances, and it seems likely that the explanation for this lies in the hydrolytic and adsorptive behavior. [Pg.1370]

Since the niobium-BPR complex is insoluble in water, gelatine is added to give a stable colloidal dispersion. The colour reaction proceeds so slowly that maximum absorbance is attained only after 90 min, after which it remains constant. The greatest sensitivity is obtained in solutions buffered between pH 5.8 and 6.6 with ammonium acetate. [Pg.295]

As shown in Table II, there was an increase in sorption with increasing ionic strength at pH 7.1, the opposite being obtained at pH 5. Such phenomena may be explained in terms of the types of sorbing species postulated earlier. It has been shown (20, 21, 22) that the nature of the sorption of radiocolloids from aqueous solutions differs from ionic sorption. For example, Schubert and Conn (23) found that the sorption of colloidal zirconium and niobium on a cation exchanger increased with increasing electrolyte concentration, while addition of electrolyte effectively competed with and reduced sorption of the ionic species. [Pg.303]

The United Slates, the Soviet Union, and Japan lead in the study of flotation techniques to irent radioactive wastes.1,7 The metals of interest inclnde cobalt, strontium, zirconium, niobium, ruthenium, cesium, and cerium, as well as rhodium and yttrium. Tbe studies, all of which employed precipitate or adsorbing colloid flotation, indicated that an average of over 90% removal is achievable. Some removals approached 100%. [Pg.816]


See other pages where Niobium Colloidal is mentioned: [Pg.11]    [Pg.629]    [Pg.155]    [Pg.199]    [Pg.468]    [Pg.89]    [Pg.7]    [Pg.123]    [Pg.416]    [Pg.725]    [Pg.75]    [Pg.473]    [Pg.357]    [Pg.287]    [Pg.85]    [Pg.138]   
See also in sourсe #XX -- [ Pg.135 ]




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