Study on the generation mechanism of reactive oxygen species on calcium peroxide by chemiluminescence and UV-visible spectra

In the present work, the generation mechanism of reactive oxygen species (ROS) on calcium peroxide (CaO2,) was studied. A very intense chemiluminescence (CL) signal was observed when adding an aqueous solution of luminol or 2-methyl-6-(4-methoxyphenyl)-3,7-dihydroimidazo[1,2 alpha]-pyrazin-3-one hydrochloride (MCLA) to a suspension of CaO2. The ROS released on CaO2 were thought to be oxidizing agents leading to CL, and were characterized by CL, UV-visible (UV-vis) spectra and the effective scavengers of the special ROS. From experimental results, the hydroxyl (center dot OH) and superoxide (center dot O-2(-)) radicals were suggested to exist on the surface of CaO2. A reaction scheme for the formation of the ROS on CaO2 was also proposed and discussed. Of more interest was the finding that the CaO2 which released the center dot OH and center dot O-2(-) on the surface exhibited good transition properties compared with alkaline-earth metal peroxides of the same group (MgO2, BaO2). Copyright (c) 2007 John Wiley & Sons, Ltd.