The effects of a microbial ligand on Pb sorption to montmorillonite clay and on Pb carbonate formation

Siderophores are organic ligands released by aerobic microorganisms and plants to acquire Fe; they may also bind other metals such as Pb, affecting Pb sorption and nucleation and growth of Pb-bearing minerals. Batch experiments were used to determine the effects of the siderophore desferrioxamine B (DFOB) on Pb sorption to Na- and Ca- montmorillonite (mmt) clay at pH 3-7.5 and background electrolyte NaClO4 and Ca(ClO4)2 at 0.1 and 0.01 M concentrations. DFOB was observed to have complex pH- and ionic-strength dependent effects on Pb sorption to mmt. Lowering the electrolyte concentrations was found to increase Pb sorption to Na-mmt but had no change of Pb sorption for Ca-mmt.

The effects of DFOB 0 to 0.020 M on formation of cerussite (PbCO3) and/or hydrocerussite (Pb3(CO3)2(OH)2) were also investigated, and synthesized particles analyzed by XRD, microscopic and spectroscopic methods. DFOB was found to affect particle size, morphology, and twinning.