Abatement of the Inhibitory Effect of Chloride Anions on the Photo-Fenton Process

AMILCAR MACHULEK JR.; JOSÉ E. F. MORAES; CAROLINA VAUTIER-GIONGO; CRISTINA A. SILVERIO; LEIDI C. FRIEDRICH; CLÁUDIO A.O. NASCIMENTO; MÓNICA C. GONZALEZ; FRANK H. QUINA

ENVIRONMENTAL SCIENCE & TECHNOLOGY

ACS

Año: 2007 vol. 41 p. 8459 - 8463

0013-936X

The photo-Fenton reaction (Fe2+/Fe3+, H2O2, UV light) is strongly inhibited by high concentrations of added chloride ions. In this work, it is shown that the inhibition of the photo-Fenton degradation of synthetic phenol wastewater solutions by chloride ions affects mainly the photochemical step of the process, having only a slight effect on the thermal or Fenton step. Kinetic studies of the reactions of oxoiron (IV) (FeO2+) with phenol indicate that if FeO2+ is formed in the photo-Fenton degradation, its role is likely minor, not being affected by the presence of chloride ions. Finally, it is shown that the inhibition of the photo-Fenton degradation of synthetic phenol and gasoline wastewater solutions in the presence of chloride can be circumvented by maintaining the pH of the medium at or slightly above 3 throughout the process, even at high chloride ion concentrations (0.5 M).