effect of desferrioxamine-b(dfo-b) siderophore on lead (pb) sorption by montmorillonite

abstract siderophores are of important factors influencing bioavailability and fate of heavy metals in the arid and semi-arid soils. they are low molecular weight organic ligands excreted by aerobic soil microorganisms and some plants roots to acquire fe. siderophores may also complex other metals such as pb .the main objective of this study was to investigate the effects of dfob-siderophore on sorption of pb on montmorillonite. the sorption of pb on montmorillonite was studied as a function of ph (sorption envelopes) and as a function of pb concentration (sorption isotherms) in the presence of siderophore using a 24–h batch equilibration experiment. the results of sorption envelopes showed that the siderophore increased sorption of pb onto montmorillonite in all solution ph, specially at ph ≥5. the results of equilibrium test (isotherms) revealed that removal of pb from solution was not affected by siderophore at ph=4.5, while the siderophore strongly influenced the isotherm shape and increased pb sorption onto montmorillonite at ph=6.5. the equilibrium data is best described by a freundlich isotherm, in which the values obtained for the kf constant were 4.8 and 196.5 and for n constant were 0.8 and 2.1 in the absence and presence of the siderophore, respectively. these values are indication of high sorption affinity of pb on montmorillonite in the presence of the siderophore.