Chemical degradation of PCB in the contaminated soils slurry: Direct Fenton oxidation and desorption combined with the photo-Fenton process

Abstract

This paper reports the results of the direct treatment of PCBs sorbed to solid particles (glass beads and sand) employing the Fenton process. The results obtained with contaminated sandy soils show 98% removal of the original PCB structure and 82% dechlorination, all within a reaction time of 72 hours. The degree of removal was observed to be dependent on the level of congener chlorination. The optimized conditions were: 5% H₂O₂; 100 ppm Fe^{3 +}; sandy soil mass/volume of oxidizing solution ratio (m/V) of 1/3 g/mL, vigorous agitation and dispensed with the need for heat. Results obtained by applying an integrated desorption treatment followed by photo-Fenton oxidation to sandy soils contaminated with PCBs are also present in this paper. Desorption of PCBs with surfactant solutions took place to an extent of around 90% (92.2% with K-perfluoroalkyl sulfonate, FT800, and 87% with Lineal Alkyl benzene Sulfonate, LAS), while photo-Fenton oxidation at 254 nm achieved degradation percentages close to 100% in 30 minutes for PCBs in solution, both with FT800 (98%) and LAS (97%) surfactants.

Keywords:

• Catalyzed hydrogen peroxide treatment
• hydroxyl radical
• integrated treatment
• surfactant
• kinetics

Acknowledgments

The authors wish to express their thanks to the Interministerial Commission of Science and Technology and the Spanish Ministry of Education and Culture for their economic support and to A.S. Weber from the New York State Center for Hazardous Waste Management (Buffalo, N.Y.) and J. Kiwi from the Swiss Federal Institute of Technology in Lausanne (EPFL) for their valuable scientific collaboration.