Influence of Temperature, pH, and DOM Source on Hydroxyl Radical/Ozone Ratios During Ozonation of Natural Waters

摘要

The ozonation of model systems and several natural waters was examined in bench-scale batch experiments. In addition to ozone (O_3) measurements, the concentration of an in situ hydroxyl radical probe compound was monitored, thus providing information on the steady-state concentration of hydroxyl radicals (·OH) . A new parameter, R_(ct), representing the ratio of the ·OH-ct-value and O_3-ct-value was calculated as a function of reaction time. For most waters tested, R_(ct) was a constant value for the majority of the reaction. Therefore, R_(ct) corresponds to the overall, net ratio of the ·0H concentration to the O_3 concentration in a given water, inclusive of all initiating, promoting, and inhibiting chain reactions. Ozonation of several natural waters were compared with respect to their R_(ct), ·OH-ct-, and O_3-ct-values. Additional experiments examined the effects of reaction temperature and pH on these parameters.