Thermospectroscopic study of the adsorption mechanism of the hydroxamic siderophore ferrioxamine B by calcium montmorillonite.

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 ferrioxamine B 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 temperature range 25-360 degrees C and thermo-FTIR spectroscopy in the temperature range 25-170 degrees C.

A Fifth OH-Stretching Band in IR Spectra of Kaolinites.

Transmission infrared spectra of different kaolinites were studied by curve fitting. These spectra generally exhibit four hydroxyl stretching bands. In this article we show that a fifth OH band (already identified in Raman and photoacoustic IR spectra of kaolinites) is also observed in transmission IR spectra of hydrothermal and authigenic kaolinites, which have a high degree of crystallinity.

Infrared Study of the Intercalation of Kaolinite by Caesium Bromide and Caesium Iodide.

CsBr- and CsI-kaolinite intercalation complexes were synthesized by gradually heating caesium halide disks of the DMSO-kaolinite intermediate up to 330 degreesC. Infrared spectroscopy revealed two types of complexes with the caesium salts: almost nonhydrous, obtained during thermal treatment of the DMSO complex, and hydrated, produced by regrinding the disk in air. Comparison of band positions for CsBr-kaolinite and CsI-kaolinite with those for the CsCl complex (observed in a previous study) shows that the strength of the hydrogen bond between the intercalated halide and the inner surface hydroxyl decreases on the order CsCl > CsBr > CsI.