Arsenic removal from water employing heterogeneous photocatalysis with TiO2 immobilized in PET bottles

Arsenic oxidation (As(III) to As(V)) and As(V) removal from water were assessed by using TiO₂ immobilized in PET (polyethylene terephthalate) bottles in the presence of natural sunlight and iron salts. The effect of many parameters was sequentially studied: TiO₂ concentration of the coating solution, Fe(II) concentration, pH, solar irradiation time; dissolved organic carbon concentration. The final conditions (TiO₂ concentration of the coating solution: 10%; Fe(II): 7.0 mg l⁻¹; solar exposure time: 120 min) were applied to natural water samples spiked with 500 μg l⁻¹ As(III) in order to verify the influence of natural water matrix. After treatment, As(III) and total As concentrations were lower than the limit of quantitation (2 μg l⁻¹) of the voltammetric method used, showing a removal over 99%, and giving evidence that As(III) was effectively oxidized to As(V). The results obtained demonstrated that TiO₂ can be easily immobilized on a PET surface in order to perform As(III) oxidation in water and that this TiO₂ immobilization, combined with coprecipitation of arsenic on Fe(III) hydroxides(oxides) could be an efficient way for inorganic arsenic removal from groundwaters.