Arsenic (V) removal with nanoparticulate zerovalent iron: effect of UV light and humic acids.

M.E. MORGADA; I.K. LEVY; V. SALOMONE; S.S. FARÍAS; G. LÓPEZ; M.I. LITTER

CATALYSIS TODAY

Elsevier

Lugar: Amsterdam; Año: 2009 vol. 143 p. 261 - 268

0920-5861

Results on As(V) removal in the presence of oxygen using the zerovalent iron technology with commercial iron nanoparticles (NanoFe1) are presented, showing the effect of (NanoFe1) mass, UV light and addition of humic acids. The nanosized iron particles (NZVI) were characterized in their particle size, surface area and constituent phases. As(V) removal was rapid and increased with NZVI mass (0.005–0.1 g L-1) attaining more than 90% after 150 min of time contact with the optimal NanoFe1 concentration. The removal followed a biexponential kinetic decay, with rate constants increasing with NZVI mass. (NanoFe1) presented an outstanding ability to remove As due to not only a high surface area and low particle size but also to a high intrinsic activity. Humic acids (HA) decreased around 50% the removal efficiency in the dark, indicating competition with As(V) for active surface sites. In contrast, UV light doubled removal rates, the process being evenmore enhanced in the presence of HA, with an almost total arsenic removal within 4 h. In all cases, adsorption on iron corrosion phases was found the main mechanism of As(V) removal, promoted by formation of Reactive Oxygen Species and enhanced under UV irradiation by the formation of multiple active species. Preliminary results with As-polluted groundwater of the Chacopampean Plain of Argentina (Tucuma´n Province) are also reported. Addition of NanoFe1under UV irradiation for 3 h resulted in As contents well in agreement with the regulations (<10 mg L_1).