Infrared spectroscopy of NH4+-bearing and saturated clay minerals: A review of the study of layer charge

2006 ◽  
Vol 34 (1-4) ◽  
pp. 22-30 ◽  
Author(s):  
S. Petit ◽  
D. Righi ◽  
J. Madejová
Clay Minerals ◽  
2007 ◽  
Vol 42 (3) ◽  
pp. 373-398 ◽  
Author(s):  
M. Egli ◽  
A. Mirabella ◽  
G. Sartori ◽  
D. Giaccai ◽  
R. Zanelli ◽  
...  

AbstractTwo soil profile sequences on paragneiss debris in the Val di Rabbi (Northern Italy) along an altitude gradient ranging from 1200 to 2400 m a.s.l. were studied to evaluate the effect of aspect on the weathering of clay minerals. All the soils had a coarse structure, a sandy texture and a low pH. Greater weathering intensities of clay-sized phyllosilicates (greater content of smectites) were observed in soils on the north-facing slope. On the south-facing slope, smectite was found only in the surface horizon of the soil profile at the highest altitude. Hot citrate treatment of north-facing soils revealed the presence of low-charged 2:1 clay minerals, the expansion of which was hindered in the untreated state by interlayered polymers. However, the hot citrate treatment encountered some problems with the samples of the south-facing soils: as confirmed by Fourier transform infrared spectroscopy, the hot citrate treatment was unable to remove all interlayer Al polymers. The 2:1 phyllosilicates were not expanded by ethylene glycol solvation in several samples, although thermogravimetric analyses indicated the presence of clay minerals with interlayer H2O. At the same time, the collapse of clay minerals to 1.0 nm following K-saturation was evident. Theoretically, this should indicate that 2:1 phyllosilicates had no evident substitution of trioctahedral cations (Mg2+, Fe2+) by dioctahedral cations (Al3+ and Fe3+). X-ray diffraction analysis of the d060 region and determination of the layer charge of clay minerals by the long-chain (C18) alkylammonium ion, however, did not confirm this. A transformation from trioctahedral to dioctahedral species was observed and low-charge clay minerals (ξ ~0.30) were identified in the surface horizons of the south-facing sites. In the south-facing soils, the podzolization process was less pronounced because of a lower water flux through the soil and probably less complexing organic molecules that would remove the interlayer polymers. Besides the eluviation process, clay minerals underwent a process of ionic substitutions in the octahedral sheet that led to the reduction of the layer charge. This process was more obvious in the north-facing sites.


Clay Minerals ◽  
1999 ◽  
Vol 34 (3) ◽  
pp. 439-445 ◽  
Author(s):  
M. Pelletier ◽  
L. J. Michot ◽  
O. Barrès ◽  
B. Humbert ◽  
S. Petit ◽  
...  

AbstractIn order to assess the influence of tetrahedral sheet charge on the hydroxyl-stretching vibration in clay minerals, a series of synthetic Na-saponites, with increasing layer charge, was studied by infrared (IR) spectroscopy. When recorded after KBr dilution either in transmission or diffuse reflectance, the IR spectra exhibit a component at ~3710 cm-1, the intensity of which increases linearly with increasing layer charge. When experiments are carried out without any dilution of the samples, this component is not observed, suggesting a Na+/K+ exchange upon mixing of the sample with KBr. The spectra obtained for K-saponite confirm this exchange. This shows that the dilution procedure can lead to serious misinterpretations of IR spectra in the OH-stretching region.


2010 ◽  
Vol 64 (12) ◽  
pp. 1379-1387 ◽  
Author(s):  
Michal Ritz ◽  
Lenka Vaculíková ◽  
Eva Plevová

2020 ◽  
Vol 567 ◽  
pp. 274-284 ◽  
Author(s):  
Brian Grégoire ◽  
Baptiste Dazas ◽  
Fabien Hubert ◽  
Emmanuel Tertre ◽  
Eric Ferrage ◽  
...  

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