Removal of Trace Arsenic Based on Biomimetic Separation

A novel method was proposed to determine the key species (ions or function groups) with strong arsenic fixation capacity as well as the auxiliary species in the fixation. The elements and species involved in the fixation of arsenic were surmised based on the change of the elemental composition in a plants roots, and their roles in the fixation of heavy metals were assessed using simulated precipitation and adsorption of arsenic under near-physiological conditions (20-35 degrees C and pH 6-7.5) using chemicals containing the surmised species. The results showed that copper(II) hydroxide and/or carbonate possessed strong As-V fixation capacity, while Fe3+ ions played an auxiliary role in the precipitation of As-V. A combination of Fe2+ and HS-/S2- ions or a combination of Fe2+ ions and -SH groups had strong As-III fixation capacity. On the basis of the obtained information, an adsorbent using the components (species), which commonly exist in plants, was designed and prepared. The adsorbent was excellent in removing trace As-III, with residual concentrations as low as 0.03 mg/L.