TREATMENT OF POLLUTED WATER BY GAS-LIQUID DISCHARGE PLASMA REACTOR: ROLE OF OZONE AND ACTIVE SPECIES

摘要

The objective of this study was to elucidate the oxidation pathways in a falling film gas-liquid discharge reactor. Experiments have been conducted with different types of organic pollutants: an unsaturated pollutant reacting with ozone and hydroxyl radical (phenol) and saturated pollutants reacting only with hydroxyl radical (ethanol, 1-heptanol, acetic acid). The results obtained with phenol were similar to the performances reported in other studies with plasma discharge reactors in terms of energetic efficiency (0.9 g/kWh) and reaction by-products. With saturated pollutants, the removal performances were clearly related to their values of Henry's law constant k_(h) (M.atm~(-1)). Pollutants characterized by a low k_(h) were better removed than those having a high k_(h). As a result, the pollutants were classified as follows in terms of removal efficiency: 1-heptanol > ethanol > phenol > acetic acid. The low pollutants concentrations (<1 ppm) measured in the gas exiting the reactor indicated that the removal was not the only consequence of evaporation but was mainly due to the reaction of the pollutant with the active species created by the discharge in the gas phase above the liquid surface.