Abstract
The treatment of aqueous solutions containing arsenic has been studied using TiO2, zero valent iron (ZVI), and a combined system (TiO2+ZVI) under UV-irradiation. The reactions were carried out for 10mgL−1 of As(III) at two initial pH values (9 and 3). The experimental results evidenced the significant influence of the pH of the aqueous solution on both the oxidation rate of As(III) and the effectiveness for overall As uptake. The kinetics of As(III) oxidation were enhanced at pH 3, especially in the ZVI system. Acid pH was also found to promote the uptake of produced As(V) when metallic iron was used, which was explained by the adsorption of arsenate on the iron oxides/hydroxides generated by the ZVI corrosion. Compared to ZVI, the rate of As(III) oxidation was always higher when TiO2 was present, achieving a complete depletion of arsenite concentration. However, TiO2 showed a limited capacity for As(V) adsorption, which was mostly released to the aqueous solution. With both ZVI and the combined system (TiO2+ZVI) final As concentrations of 5 and 3μgL−1 were respectively attained, values below the WHO recommended limit (10μgL−1) for arsenic in drinking water.
Published Version
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