Reactivity of colloidal silica toward hydroxyl radical and hydrated electron

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

Reactions of colloidal silica with OH radical and hydrated electron were studied by pulse radiolysis technique. Colloidal silica samples were prepared by hydrolysis of TEOS (Si(OCH)) and solutions containing colloidal silica were compared to control solutions containing the filtrate of the colloidal silica samples, in order to avoid the effect of stabilizer and other impurities. For hydrated electron, transient light absorption was measured directly. Decay kinetics of hydrated electron were observed to be almost identical in the presence and absence of colloidal silica. On the other hand, for OH radical, absorption of carbonate radical formed by the reaction of OH radical with bicarbonate ion was measured to decrease in the presence of colloidal silica. This result indicates a competitive reaction between colloidal silica and bicarbonate ion with OH radical, and the reactivity of colloidal silica toward OH radical.