The thermal behaviour of the intercalation complex of a dickite from Tarifa, Spain, with dimethylsulfoxide was studied by
high-temperature X-ray diffraction, differential thermal analysis and thermogravimetry, and attenuated total reflectance infrared
spectroscopy. The ATR-FTIR study indicated that the heating between room temperature and 75C produced the elimination of
adsorbed molecules. Above this temperature the elimination of intercalated molecules occurs through several stages. Loss of
6.5% of the intercalated DMSO first causes a slight contraction of the basal spacing at 90şC due to a rearrangement of the
DMSO molecules in the interlayers positions. This contraction is followed by the formation of a single layer complex and the
restoring of the dickite structure, at 300C, when the loss of intercalated species have been completed.
thermo-infrared spectroscopy analysis. Based on these analyses, the kaolinite–DMSO intercalationcomplex of a low defect (well crystallized) kaolinite from Zhangjiakou in China was prepared. The thermal behavior of the complex heated in different
Authors:Hongfei Cheng, Jing Yang, Ray L. Frost, Qinfu Liu, and Zhiliang Zhang
the formation of new organoclay nanohybrid materials, intercalation can lead to the covalent grafting of organic molecules. Therefore, kaolinite-potassium acetate intercalationcomplex has the potential to be a precursor for polymer
The comparison of thermal stabilities of different organoclay intercalation complexes is presented in this work. Montmorillonite/monomer and montmorillonite/polymer intercalation complexes with similar basal spacings show a pronounced difference in changes of d001 values after 30 min heating. The hydrophilic and/or organophilic surface modification of the starting montmorillonite is an important factor affecting the intercalated amount of organic material and thus the expansion of the sheet silicate structure.
Dimethylsulfoxide (DMSO) kaolinite complexes of low-and high-defect kaolinites were studied by thermo-IR-spectroscopy analysis.
Samples were gradually heated up to 170°C, three hours at each temperature. After cooling to room temperature, they were pressed
into KBr disks and their spectra were recorded. From the spectra two types of complexes were identified. In the spectrum of
type I complex two bands were attributed to asymmetric and symmetric H-O-H stretching vibrations of intercalated water, bridging
between DMSO and the clay-O-planes. As a result of H-bonds between intercalated water molecules and the O-planes, Si-O vibrations
of the clay framework were perturbed, in the low-defect kaolinite more than in the high-defect. Type II complex was obtained
by the thermal escape of the intercalated water. Consequently, the H-O-H bands were absent from the spectrum of type II complex
and the Si-O bands were not perturbed. Type I complex was present up to 120°C whereas type II between 130 and 150°C. The presence
of intercalated DMSO was proved from the appearance of methyl bands. These bands decreased with temperature due to the thermal
evolution of DMSO but disappeared only in spectra of samples heated at 160°C. Intercalated DMSO was H-bonded to the inner-surface
hydroxyls and vibrations associated with this group were perturbed. Due to the thermal evolution of DMSO the intensities of
the perturbed bands decreased with the temperature. They disappeared at 160°C together with the methyl bands.
DMSO-kaolinite complexes of low- and high-defect Georgia kaolinite (KGa-1 and KGa-2, respectively) were investigated by thermo-XRD-analysis.
X-ray patterns showed that DMSO was intercalated in both kaolinites with a d(001)-value of 1.11 nm (type I complex). The samples were gradually heated up to 170°C and diffracted by X-ray at room-temperature.
With the rise in temperature, due to the thermal evolution of the guest molecules, the relative intensity of the 1.11 nm peak
decreased and that of the 0.72 nm peak (neat kaolinite) increased indicating that the fraction of the non-intercalated tactoids
increased. The 1.11 peak disappeared at 130–140°C. During the thermal treatment of both complexes two additional peaks appeared
at 110 and 120°C, respectively, with d-values of 0.79–0.94 and 0.61–0.67 nm in DMSO-KGa-1 and 0.81–0.86 and 0.62–0.66 nm in DMSO-KGa-2, indicating the formation
of a new phase (type II complex). The new complex was obtained by the dehydration of type I complex and was composed of intercalated
DMSO molecules which did not escape. The new peaks disappeared at 150–160°C indicating the complete escape of DMSO.
dickite from Tarifa (Spain) was used to study the influence of the intercalation
and the later deintercalation of hydrazine on the dehydroxylation process.
The dehydroxylation of the untreated dickite occurs through three overlapping
endothermic stages whose DTA peaks are centred at 586, 657 and 676C.
These endothermic effects correspond, respectively, to the loss of the inner-surface,
the inner hydroxyl groups, and the loss of the water molecules, product of
dehydroxylation process, which has been trapped in the framework of the dehydroxylated
The intercalation of hydrazine in the interlayer space
of dickite and the later deintercalation affect the dehydroxylation process.
It occurs through only two endothermic stages which DTA peaks are centred
at 575 and 650C. The first corresponds to the simultaneous loss of both
the inner and the inner-surface hydroxyl groups, whereas the second one is
analogous to that at 676C observed in the DTA curve of untreated dickite.
These effects appear shifted to lower temperatures compared to those observed
in the untreated dickite.
Layered crystalline zirconium phosphates (-, and - modes) and cerium arsenate as well as some of Li or Na-forms were investigated in several polar organic media. Under such conditions dehydration or intercalation processes take place. The X-ray diffraction and the thermoanalytical data refer to the structure and composition of the dehydrated materials or intercalation complexes respectively.
Authors:I. Lapides, N. Lahav, K. H. Michaelian, and S. Yariv
Intercalation complexes of kaolinite with a series of alkali halides (NaCl (trace amounts), KCl, RbCl, CsCl, NaBr, KBr, CsBr, Kl, Rbl and Csl) were obtained by a thermal solid state reaction between the kaolinite-dimethylsulfoxide intercalation complex and the appropriate alkali halide. The ground mixtures (1∶1 weight ratio) were pressed into disks that were gradually heated up to 250 °C for different times. X-ray diffractograms of the disks were recorded after each thermal treatment. At the end of the thermal treatment the disks were ground and basal spacings of the powders obtained. As a result of thermal treatment, alkali halide ions diffuse into the interlayers, replacing the intercalated dimethylsulfoxide molecules. Such a replacement may take place only if the thermal diffusion of the penetrating species is faster than the evolution of the intercalated organic molecule. With increasing temperature the intercalated salt diffused outside the interlayer space or underwent a thermal hydrolysis which resulted in the evolution of hydrogen halides from the interlayer space. Consequently, the amounts of intercalation complexes decreased at elevated temperatures.