TiO2 photocatalytic degradation of PCBs in soil-water systems containing fluoro surfactant

Titanium dioxide-mediated photodegradation of Polychlorinated biphenyls (PC Bs) in soil/aqueous systems with added fluorinated surfactant was investiga ted. PCBs can bind tightly to organic matter in the soil, especially in age d, contaminated soil. Experiments showed an effective PCB photocatalytic de gradation in mixed systems of soil/clay with anionic fluorinated surfactant FC-143 and TiO2. The FC-143 surfactant is stable in this photochemical pro cess. PCB degradation rates in samples followed the order: spiked clay > sp iked soil > Hudson River bank soil. The results suggest that anionic fluori nated surfactant may form semimicelles and/or admicelles on the surface of positively charged TiO2. The hydrophobic surface of TiO2 can provide a nonp olar phase that acts as a partioning medium for hydrophobic PCBs. Therefore , PCBs in soil can be released to the semimicelle and/or admicelle on the T iO2 surface and are effectively photodegraded in a dispersion containing an ionic fluorinated surfactant. The combination of surfactant extraction and photooxidation forms the basis for a novel two-stage process for the remova l and destruction of PCBs from soil. (C) 2000 Elsevier Science Ltd. All rig hts reserved.