(a) Adsorption of Fe-EDTA, Fe-DFOB, and Fe-DFOD complexes on goethite at pH 6 as a function of SDS concentration. The total concentration of Fe-ligand complexes was 30 µM. (b) Adsorption isotherm of Fe-DFOB to goethite at pH 6 in the presence of 0, 15, 800 µM total SDS. For (a) and (b) 0.01 M NaClO4, 2.5 g/L goethite, 24 h equilibration time. Error bars indicate the standard deviation of three replicates.