Transient kinetics of hydroxyl radical and hydrated electron in aqueous solution containing colloidal silica

Kumagai, Yuta   ; Muroya, Yusa*; Yamada, Reiji; Nagaishi, Ryuji ; Katsumura, Yosuke*

Transient kinetics of hydroxyl radical and hydrated electron in aqueous solution containing colloidal silica were studied using pulse-radiolysis technique in order to understand the coexistent effect of silica on the radiation-induced reaction. Nano-sized colloidal silica prepared by Stober method allowed time-resolved optical absorption measurement in mixture of water and silica. In the presence of colloidal silica, the reaction of hydroxyl radical with ferrocyanide ion was inhibited. Change in the transient absorption in UV region was also observed and it suggests formation of a product due to a reaction of hydroxyl radical with colloidal silica. The results suggest that hydroxyl radical was scavenged by colloidal silica. On the other hand, little effect of colloidal silica on the decay of hydrated electron was observed. Therefore it is unlikely that an interaction between hydrated electron and colloidal silica significantly changes the reaction pathway of hydrated electron.