Heterogeneous production of perchlorate and chlorate by ozone oxidation of Cl-

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2011-08

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ABSTRACT Perchlorate (ClO4-) is proved to be of atmospherically produced, it found to be widely spread in environment although in a low concentration. Studies had demonstrated atmospheric ClO4- formation and mechanism of ClO4- formation by UV irradiation and ozone oxidation of Cl- and oxy-chlorine species. They also analyzed environmental condition impacts on perchlorate formation. However, little information is known about ozone oxidation of dry Cl-. This study mainly focused on factors that impact ClO4- formation through ozone oxidation of chloride in the dry condition. Reaction time, mass of initial Cl-, reactor surface area, humidity in the reactor, and the physical form of Cl- are factors that been systematically evaluated in this experiment. The mass of ClO4- formed in the reactor increased roughly linearly (R2 = 0.98; R2 = 0.83) with respect to reaction time. ClO4- mass did not consistently vary with an increase in Cl- mass while ClO3- increased 3 order of magnitude (0.043 μg- 37.93 μg) over the 4 order range of Cl- masses reacted. ClO4- formed mass in the humidity system was similar with it produced in the dry system, however, ClO3- mass increased by 2 orders of magnitude in humidity system compared to dry system. The increase of glass surface area could increase the production of ClO4- in this experiment, it seems like glass tube surface could act as catalyst to accelerate ClO4- formation. ClO4- mass produced by HCl gas was relatively the same with it produced by NaCl salts, so, Cl physical phase do not have impact on ClO4- production.

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