in situ X-ray absorption experiment to study the competitive As(III) and As(V) adsorption in UiO66/polydopamine

UiO-66 is an effective adsorbent for As(V) from water. The main adsorption sites for As(V) are defective sites in the Zr cluster of UiO-66. However, the more toxic and neutral As(III) cannot be effectively removed from water. Through our post-synthetic modification strategy, we have doped UiO-66 with iron, which in turn facilitates the polymerization of dopamine inside the pores. We have found that As(III) is oxidized in the iron-doped UiO-66/polydopamine which leads to an increased selectivity for As(III). This makes this material a promising adsorbent for total As from water sources with mixed As(III) and As(V) contamination. We will use X-ray absorption spectroscopy to study the Fe, Zr and As K-edge to fully characterize the as-synthesized materials, and to gain insight into the oxidation/adsopriton mechanism.