VALENCY STABILIZATION OF POLYVALENT IONS DURING GAMMA-IRRADIATION OF THEIR AQUEOUS-SOLUTIONS BY SACRIFICIAL PROTECTION .2. VALENCY STABILIZATION OF CE(IV) BY BROMATE IONS
Mf. Barakat et Mm. Abdelhamid, VALENCY STABILIZATION OF POLYVALENT IONS DURING GAMMA-IRRADIATION OF THEIR AQUEOUS-SOLUTIONS BY SACRIFICIAL PROTECTION .2. VALENCY STABILIZATION OF CE(IV) BY BROMATE IONS, Journal of radioanalytical and nuclear chemistry, 211(2), 1996, pp. 461-471
The various aspects of valency stabilization of polyvalent ions during
gamma-radiolysis have been further investigated. Ce(IV) ions, which a
re normally reduced in their aqueous solution. were found to be stabil
ized for increasing periods of time when they were irradiated in the p
resence of increasing amounts of bromate ions. It was found that the a
ddition of about fifteen times excess of bromate ions to a 10(-3) N Ce
(IV) solution stabilized the cerium ions in the tetravalent state for
about 120 hours during irradiation at a dose rate of 336 Gy/h. Increas
ing the amount of bromate used resulted in a subsequent increase in th
e protection time. It has been also noted that while bromate ions prot
ected Ce(IV) in solution, the latter ions showed a clear protective ef
fect on the bromate used, i.e., there is a mutual protective effect. T
he probable mechanisms, conditions and limitations of the protection p
rocess have been discussed. Based on the data obtained in the present
work, it has been suggested that the protection of Ce(IV) ions by brom
ate ions in aqueous solutions during gamma-radiolysis is very probably
due to the preferential interaction of bromate with the reducing radi
olysis products of water which are capable of reducing Ce(IV) to Ce(II
I).