Novel Magnetic Iron-Copper Nanocomposites as Photocatalysts for As(III) Oxidation

MORAN AYALA, LUCIA; APARICIO, FRANCISCA; CARLOS, LUCIANO; MAGNACCA, GIULIANA

Encuentro; XIV Encuentro Latinoamericano de Fotoquímica y Fotobiología (ELAFOT); 2019

At least four million people in South American countries drink water containing arsenic at levels that pose a risk to their health. Therefore, developing affordable and efficient techniques to remove As from drinking water is critical to protect human health.We here employ magnetic iron and copper nanocomposites (NCs) as both adsorbents and photocatalysts for the oxidation of As(III) to the less toxic As(V) species. The synthesis of the NCs was made by following the precursor method1,using bio-Based Substances (BBS), which are humic-like compounds, isolated from urban composting biowastes as complexing agents. The complexes of Fe3+ and Cu2+ with BBS were heated up to 400ºC in N2.Samples containing the NCs (A350 = 0.50) and 3 mM As (III) were irradiated for 60 min in a RPR Rayonet reactor containing 8 lamps with emission centered at 350 nm. The amount of As(V) determined by a colorimetric method3 was larger in the air-saturated than in the Ar-saturated samples (Figure 1a). Laser flash-photolysis experiments (λexc = 355 nm) show the broad absorption characteristic of the formation of h+/e- upon irradiation. The reciprocal of the transient decay (τ) increases with increasing concentration of As(III) up to 0.5 mM and then reaches a plateau (Figure 1b), indicating a reversible one-electron oxidation of As(III) by h+.The amount of total As and As(III) were evaluated after irradiation of samples containing the NCs and As(III) to obtain information of the relative importance of the adsorption and photocatalysis routes for the removal of As with our NCs under different conditions.