Reactivity of Freshly Formed Fe(III) in Synthetic Solutions and (Pore)Waters: Voltammetric Evidence of an Aging Process

摘要: We report a laboratory and field study that demonstrates soluble Fe(III) complexed to organic ligands exists in sediment porewaters. Synthetic solutions of with the ligand Tris were used simulate complexation natural waters. Size fractionation using gel filtration chromatography shows at least three different molecular mass species coexist. The masses FeIIIx−Trisy complexes increase time, suggesting aggregation occurs solution. Soluble is detected by voltammetry mercury drop electrode when it an ligand. Depending on age Fe(III), two voltammetric waves can be observed:  ca. −0.3 V for “freshly” formed more negative potential “aged” Fe(III). A mathematical model was successfully developed assess mechanism this aging process. This involves oxidation adsorption Fe(II), aggregation, precipitation complexes. are extremely...