Mechanisms of goethite dissolution in the presence of desferrioxamine B and Suwannee River fulvic acid at pH 6.5

摘要: Abstract Siderophores are Fe3+ specific low MW chelating ligands secreted by micro-organisms in response to Fe stress. Low organic acids such as oxalate have been shown enhance siderophore mediated dissolution of oxides. However, the effect fulvic acid presence on function remains unknown. We used batch experiments investigate release from goethite goethite–fulvic acid–desferrioxamine B (goethite–SRFA–DFOB) ternary system. Experiments were conducted at pH 6.5 while varying reagent addition sequence. FTIR and UV–Vis spectroscopy employed characterise Fe–DFOB, Fe–SRFA DFOB–SRFA complexes. Iron released SRFA alone was below detection limit. In both DFOB, dissolved increased with reaction time, complex, where introduced prior DFOB. data show that system, is complexed primarily oxygen DFOB hydroxamate group, whilst carboxylate C O forms an electrostatic association terminal NH3+ propose sorbed lowers net positive charge oxide surface, thus facilitating adsorption cationic subsequent chelation release. Furthermore, weakens Fe–O bonds increasing population kinetically labile Fe. This work demonstrates positive, though indirect role bioavailability Fe3+.