Two-phase ozonation of chlorinated organics

Abstract

Although ozonation is an effective advanced oxidation process for the destruction of hazardous organic pollutants, a single-phase ozonation system is limited by low ozone solubility, low ozone stability, and a lack of selective oxidation potential. These problems may be overcome by mixing a non-polar fluorinated hydrocarbon solvent (FC40) with the aqueous solution. The primary advantages of the FC40 solvent are that it is non-toxic, reusable, has an ozone solubility 10 times that of water, and that 85% of the ozone remains in the solvent even after 2 h. This novel two-phase process has been utilized to study the rapid destruction of trichlorophenol (TCP), pentachlorophenol (PCP), 1,3-dichlorobenzene (DCB), and trichloroethylene (TCE). Our results show that 98% of a 50 mg/l solution of TCP can be degraded 30 s if a molar ratio of 12 moles ozone/mole TCP is utilized. Further studies have reported that the two-phase system is capable of degrading nearly 92% of a 10 mg/l solution of pentachlorophenol (PCP) within 1 min when a ratio of 4.3 moles ozone/mole PCP is used. Also, 80% of a 78 mg/l solution of 1,3 dichlorobenzene (1,3-DCB) is degraded within 5 min for a 21.2 molar ratio of ozone/1,3-DCB. Furthermore, these reaction rates are not altered significantly even if high concentrations of sodium bicarbonate, a free radical scavenger, are present in the aqueous phase.