SBO in Water Detoxification: Photo-Fenton Processes at Mild Conditions

The implementation of a photo-Fenton process at mild acidic conditions is a potential environmental application for SBOs. The Fenton reagent (sacrificial amounts of hydrogen peroxide and catalytic iron salts) has been demonstrated as an efficient method for the removal of toxic xenobiotics that is enhanced upon irradiation; sunlight can be used for this purpose. In order to avoid precipitation of iron at pH above 3, several strategies have been tested. One of them involves formation of photoactive iron complexes. Humic substances have been employed for this purpose, due to their ability to complex iron. Because of its similar chemical properties, SBO are candidates for this purpose. Experiments carried out with different pollutants have shown that SBO are not good photocatalysts because of the strong screen effect associated to their color, while they are useful to drive a photo-Fenton at milder pH, as they are good complexing agents for iron. Doehlert matrixes have been employed to determine that the pH range for efficient photo-Fenton can be extended to values of ca. 5 and that optimal SBO concentration is approximately 20 mg/L. Finally, SBO have demonstrated to be non toxic, scarcely biodegradable and relatively resistant to oxidizing conditions.