A STUDY OF FORMING NIOBIUM COLLOID IN NITRIC ACID SOLUTION BY ULTRACENTRIFUGATION

The paper deals with the dependence of the colloid formation of niobium on the concentration of nitric acid and self niobium. The different concentration of niobium in the range of 1×10~(-6) to 8×10~(-5)mol/l and nitric acid in the range of 0.5 to 8.0 mol/l was investigated for observation of colloid formation by ultracentrifugation. The results show that the colloid niobium is not formed when niobium concentration is lower than 1×10~(-6) mol/l. If niobium concentration is higher than 7×10~(-6)mol/l, the colloid is observed obviously and colloid formation of niobium is increasing quickly when concentration of niobium is higher than 1×10~(-5)mol/l. The particles of colloid seem to be polydispersed when nitric acid concentration is lower than 3mol/l and monodispersed when nitric acid concentration is higher than 3 mol/l.