EPR investigation on the efficiency of hydroxyl radical production of gamma-irradiated anatase and bentonite.

Anatase and bentonite were treated by gamma rays in various conditions, and the change of the catalysts was characterized by electron paramagnetic resonance spectroscopy. Anatase gave four peaks with g(parallel) = 1.951 g(perpendicular) = 1.973, g = 1.992 and 2.005. The height of the four peaks was directly proportional to the efficiency of hydroxyl radical production, and anatase treated by gamma rays in alkaline condition showed the most efficient production. Bentonite gave a peak with g = 2.005. In contrast to anatase, the peak height was inversely proportional to the efficiency of hydroxyl radical production, and non-treated bentonite was the most efficient catalyst. Furthermore, the efficiency of hydroxyl radical production of the catalysts significantly influenced the decomposition of trichloroethylene and perchloroethylene by gamma rays.