Genuine colloidal 95Nb in HNO3 solutions

Criteria for the appearance of genuine colloidal tracer (TR) radioelements have been previously proposed on the basis of their sorption as a function of sorbent mass and pH. Thus, a sorption maximum appears on bar S-pH isotherms for a genuine colloid in advance of the manifestation of colloidal properties by the TR because the genuine colloid (hydroxide) becomes supersaturated at a certain fixed pHf. This limiting quantity characterizes the pH at which the TR colloid begins to form or the hydroxide starts to precipitate. Moreover, this quantity is determined not only by the physicochemical parameters of the sorbate but also by the perturbation of the system by the sorbent and glass in contact with the sorbate. It has been demonstrated that a concentrational dependence can be observed on the isotherms bar S-pH, log bar ε-pH, and log ε-log [m], where bar S, bar ε, and [m] are the sorption, sorption ratio, and ratio of sorbent mass to solution volume, respectively. These dependences are used for radioanalytical determination of TR in aqueous solutions by isotope-dilution methods. The ability to establish thermodynamic equilibrium after an acceptable time in TR sorption systems will be important to the utilization of sorption isotherms that depend on concentration