Thermospectroscopic Study of the Adsorption Mechanism of the Hydroxamic Siderophore Ferrioxamine B by Calcium Montmorillonite
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- 作者：Hagar Siebner-Freibach ; Yitzhak Hadar ; Shmuel Yariv ; Isaak Lapides ; and Yona Chen
- 刊名：Journal of Agricultural and Food Chemistry
- 出版年：2006
- 出版时间：February 22, 2006
- 年：2006
- 卷：54
- 期：4
- 页码：1399 - 1408
- 全文大小：178K
- 年卷期：v.54,no.4(February 22, 2006)
- ISSN：1520-5118
文摘
The behavior of iron-chelating agents in soils is highly affected by interactions with the solid phase.Still this aspect is frequently ignored. In this research the adsorption of the siderophore ferrioxamineB by Ca-montmorillonite, as a free ligand (desferrioxamine B, DFOB) and as a complex with Fe3+(ferrioxamine B, FOB), was studied, using thermo X-ray diffraction (thermo-XRD) in the temperaturerange 25-360 
C and thermo-FTIR spectroscopy in the temperature range 25-170 C. The effectof pH (4-7.5) on the adsorption was examined. Extensive use of curve-fitting analysis was requireddue to significant overlapping of the characteristic absorption bands of the various functional groups.Thermo-XRD analysis showed that both DFOB and FOB penetrated into the interlayer space of Ca-montmorillonite. FTIR results indicated strong interactions of DFOB within the interlayer, which involvedall functional groups (NH3+, secondary amide groups, and hydroxamate groups). In contrast, thefolded Fe complex of FOB retained its molecular configuration upon adsorption, and the basal spacingof the clay increased correspondingly. FOB interacted in the interlayer space of the clay, mainlythrough the NH of the secondary amide groups and NH3+, while the functional groups bound to thecentral Fe cation remained unchanged. The suspension pH had no significant effect on both DFOBand FOB adsorption at the examined range. Adsorption protected the adsorbates from thermaldegradation compared to the nonadsorbed samples up to 105 C. At 170 C both DFOB and FOBwere already partially degraded, but to a lesser extent than the nonadsorbed samples. Degradationof the molecules occurred mainly through the hydroxamic groups, which constitute the Fe-chelatingcenter in the hydroxamic siderophore.Keywords: Adsorption; Ca-montmorillonite; ferrioxamine B; FTIR spectroscopy; X-ray; siderophore
C and thermo-FTIR spectroscopy in the temperature range 25-170 C. The effectof pH (4-7.5) on the adsorption was examined. Extensive use of curve-fitting analysis was requireddue to significant overlapping of the characteristic absorption bands of the various functional groups.Thermo-XRD analysis showed that both DFOB and FOB penetrated into the interlayer space of Ca-montmorillonite. FTIR results indicated strong interactions of DFOB within the interlayer, which involvedall functional groups (NH3+, secondary amide groups, and hydroxamate groups). In contrast, thefolded Fe complex of FOB retained its molecular configuration upon adsorption, and the basal spacingof the clay increased correspondingly. FOB interacted in the interlayer space of the clay, mainlythrough the NH of the secondary amide groups and NH3+, while the functional groups bound to thecentral Fe cation remained unchanged. The suspension pH had no significant effect on both DFOBand FOB adsorption at the examined range. Adsorption protected the adsorbates from thermaldegradation compared to the nonadsorbed samples up to 105 C. At 170 C both DFOB and FOBwere already partially degraded, but to a lesser extent than the nonadsorbed samples. Degradationof the molecules occurred mainly through the hydroxamic groups, which constitute the Fe-chelatingcenter in the hydroxamic siderophore.Keywords: Adsorption; Ca-montmorillonite; ferrioxamine B; FTIR spectroscopy; X-ray; siderophore