Heavy metals desorption from synthesized and natural iron and manganese oxyhydroxides: Effect of reductive conditions

Reductive conditions in soils can lead to the dissolution of iron and manga nese oxyhydroxides, releasing heavy metal pollutants (e.g., Pb and Cd) boun d to them. The present study used hydroxylamine as a reducing agent. Labora tory batch experiments were conducted, varying pH and hydroxylamine concent rations, with artificially contaminated synthetic amorphous Fe(OH)(3s) and MnO2 and with a polluted cultivated soil, Until conditions were reductive e nough to dissolve solids, remobilization of metals depended on their surfac e complexation constant and readsorption of metal was possible. However, if conditions were sufficiently reductive, all solids were dissolved and meta ls were released into solution. A straightforward surface complexation mode l for cation desorption was carried out to support these results. (C) 2000 Academic Press.