Studies on size variation of U(IV) colloids formed in aqueous nitric acid solutions. Contributed Paper RD-06

Tetravalent Uranium readily undergoes hydrolysis even in highly acidic aqueous solutions. In the present work, solutions with concentration and pH ranges of 0.4 - 19 mM (total U) and 1- 4 respectively were investigated by light scattering technique with special emphasis on polymerization leading to colloid formation. Size variation of colloids formed at different pH was monitored. The results clearly indicate that the concentration has significant effect on particle size as well as stability of colloids. With increasing concentration, the size of colloids formed is smaller due to more crystalline nature of the colloids. Stability of colloids formed at lower concentration is greater than that of colloids formed at higher concentration. The results of this work are a clear indication that U(IV) hydrolysis does not differ from that of Pu(IV). (author)