Conclusions
Fluoride, iron (hydr)oxide such as goethite, and bicarbonate at concentrations typically found in natural groundwater samples could play an important role in sunlight photo-induced reactions in presence of H2O2 (10 mg L-1) to the abatement of organic pollutants. We have suggested that goethite fluorination may take place leading to an increase of iron (hydr)oxide photocatalytic activity while the reaction between photoinducedOH radicals and bicarbonate (HCO3-) could lead to the formation of carbonate radicals (CO3-•) which may exhibit an interesting oxidizing power able to degrade 2,4-D molecules as well.
The implications of these findings are very important since it exhibits the possibility to enhance natural abiotic sunlight photoinduced processes by the simple addition of hydrogen peroxide to remove both organic pollutants and bacteria from natural groundwater samples without the further addition of iron salts, photocatalysts, and complexing agents. Moreover, results also suggest that “natural” goethite fluoridation in real groundwater could lead to the “natural” formation of iron (hydr)oxides with enhanced photocatalytic activities.