Gamma Radiolysis of Aqueous Solutions of α-Cobalt(III) Nitrilotriacetate

Aqueous solutions of ..cap alpha..-cobalt(III) nitrilotriacetate (N) at pH 6 were irradiated with cobalt-60 ..gamma.. rays. Upon radiolysis Co(III) is reduced to Co(II) and G(-N), the reduction yield, was determined under various conditions of radiolysis. The reduction has been ascribed to direct interaction of both H and e/sup -//sub aq/ with the central metal ion. The reaction of the OH radical with N leads to the formation of iminodiacetic acid and glyoxalic acid. The degradation of the ligand has been argued as due to the possible oxidation of cobalt(III) to cobalt(IV) by the OH radical followed by oxidation of the ligand. Effects of various scavengers, e.g., t-butanol, HCOO/sup -/, NO/sub 3//sup -/, N/sub 2/O and O/sub 2/ were also studied. Competition kinetic studies were carried out by using both NO/sub 3//sup -/ and HCOO/sup -/; from the former k(e/sup -//sub aq/ + N) was found to be 9.0 x 10/sup 9/ M/sup -1/ sec/sup -1/ and from the latter k(OH + N) was found to be 3.0 x 10/sup 8/ M/sup -1/ sec/sup -1/.