Conventional processes do not eliminate PFAS in wastewater treatment plants, so they are found in trace concentrations in wastewater and rivers. Perfluorinated organic pollutants (PFAs) are toxic and persistent, that have a significant risk to human health and ecosystems. Perfluorooctanoic acid (PFOA) is one of the most common PFAs to enter water bodies, and does so primarily through untreated wastewater. Advanced oxidation processes (AOPs), in which hydroxyl free radicals •OH are generated, have been able to degrade persistent pollutants. This study aimed to evaluate the efficiency of the UV/TiO₂/H₂O₂ system, an AOP, in degrading PFOA in both deionized and surface water. A 1000 mL cylindrical glass photoreactor equipped with a cooling jacket, a cylindrical quartz tube, and 254 nm and 360 nm UV lamps was used. In UV/TiO₂/H₂O degradation tests, TiO₂ concentrations ranging from 20 to 1500 mg/L, H₂O₂ concentrations ranging from 2.22 to 6.66 g/L, and PFOA concentrations ranging from 50 to 400 µg/L were evaluated at pH 7 and 300 min of UV irradiation. A degradation of approximately 26.08% was achieved after 5 h of treatment in deionized water. Optimal UV/TiO₂/H₂O process conditions in surface water showed a degradation of 20.09%. The PFOA photodegradation experiments using TiO2 were not straightforward, due to the high persistence of PFOA and the fact that PFOA adsorbs onto glass, making chromatographic analysis of PFOA difficult. This was overcome by rigorously monitoring the traceability of PFOA adsorption on glass to ensure that the amount of PFOA degradation with TiO2 was accurately measured.
Marín et al. (Tue,) studied this question.