重クロム酸水溶液中の放射線誘起反応に対するシリカナノコロイドの共存効果

Coexistence effect of colloidal silica on the radiation induced reactions in potassium dichromate solutions

熊谷 友多   ; 永石 隆二 ; 山田 禮司

Kumagai, Yuta; Nagaishi, Ryuji; Yamada, Reiji

酸化物微粒子共存下で生じる特異な放射線誘起反応に関する基礎的知見を得るため、酸性水溶液中でのCrOの放射線誘起還元反応について、シリカナノコロイドの共存効果を調べた。CrO還元収量はシリカ共存により増加し、10wt%程度の添加で上限に達する傾向が見られた。この結果を踏まえて、OHラジカルの反応性の変化を調べるため、OHラジカル捕捉剤として-butanolを含むCrO水溶液を用いて、還元量の変化を求めた。この場合にはシリカを添加しない水溶液中でも上限値に近い収量が観測され、シリカによる増加は見られなかった。CrO還元収量の増加について、放射線による水分解生成物の収量に基づいて考察を行った結果、通常は強い酸化性のためにCrOの還元を抑制するOHラジカルが、シリカの共存により、CrOの還元に寄与することが示唆された。

The coexistence effect of colloidal silica on the radiation induced reduction of CrO in acidic aqueous solutions was investigated by -radiolysis experiments to seek a basic understanding of the coexistence effect of oxides. The reduction yield of CrO increased with the amount of silica up to around 10wt% and then seemed to reach a limit. Then a relation between the reduction yield and reactions of OH radical in the presence of sillica was studied. In the solutions containing -butanol to scavenge OH radical the yield was as high as the upper limit even in the absence of silica and no further increase was observed by the addition of silica. This result was discussed based on the yields of the products of water radiolysis, which suggests that coexisting silica has an effect on the reactions of OH radical and that the increase in the reduction of CrO are resulted from interaction between silica and OH radical.