Pulse radiolysis study on benzoate aqueous solution at elevated temperatures; Spectra, reactivity, and pKa of OH radical

パルスラジオリシス法による高温安息香酸水溶液の研究; 吸収スペクトル,OHラジカルのpKa値測定

高橋 宏行*; 勝村 庸介; Lin, M.; 室屋 裕佐*; 熊谷 友多   ; 工藤 久明*

Takahashi, Hiroyuki*; Katsumura, Yosuke; Lin, M.; Muroya, Yusa*; Kumagai, Yuta; Kudo, Hisaaki*

We have investigated the radiation chemical reactions in benzoate aqueous solution by pulse radiolysis. The transient absorption spectra, the rate constant for the reaction of benzoate ion with OH radical, and the acid dissociation constant of OH radical at high temperatures have been measured. The rate constant for the reaction of OH with benzoate ion is measured by buildup kinetic. From 25 to 175 C, the rate constant slightly increases as temperature increases, but it decreases when T 175 C. This is due to the formation of an intermediate and can be explained in terms of temperature dependence of diffusion and activation controlled reaction. Over 250 C, the rate constant obtained by kinetic method increases again. The temperature dependent pKa of OH radical, measured by taking advantage of the reaction of the OH/O with benzoate ion at different pH conditions (alkaline solutions), will be also presented.