Non Oxidisable Sorbed Fe(ll): Indicator of Strong and Weak Site Adsorption at the Goethite Surface

摘要

Experiments were conducted to study the behaviour of Fe(II) adsorbed to goethite at pH 4 with respect to exposure to dissolved O_2. Adsorption of Fe(II) onto the goethite surface was carried out under a nitrogen atmosphere, and the samples were subsequently exposed to the atmosphere for 48 hours. Adsorbed Fe(II) was determined by subtraction of the dissolved from the total Fe(II). It was found that a significant portion of the adsorbed Fe(II) did not oxidise and that this fraction increased with increasing goethite solids concentration. These results are consistent with the presence of strong and weak cation sorption sites on the goethite surface and with the strongly sorbed Fe(II) being most resistant to oxidation by dissolved O_2.