Efficiences of As uptake from aqueous solution by a natural vivianite material at 4 deg C

摘要

Several field and laboratory studies have demonstrated that secondary Fe-bearing minerals such as goethite, lepidocrocite and mackinawite have a high capacity for the uptake of As, but little work has been carried out to examine the capacity of the mineral vivianite [Fe_3(PO_4)_2 centre dot 8H_2O] for this element. We report here preliminary results of an experimental study designed to test the efficiency of As(III) and As(V) uptake by natural vivianite at acid, near-neutral and alkaline pH at T = 4 deg C, which is representative of Lake Baikal-type environments, where natural vivianite is reported to occur. The vivianite takes up between 0 and 5 percent As(III), and between 21 and 45 percent As(V), from 200 ppb solutions of these As species. Further work at 25 deg C and other solution concentrations, together with characterization of the post-sorption solids, will yield information on the efficiencies and mechanisms of As uptake by natural vivianite.