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Ray L. Frost - One of the best experts on this subject based on the ideXlab platform.
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A spectroscopic comparison of selected Chinese Kaolinite, coal bearing Kaolinite and halloysite—A mid-infrared and near-infrared study
Spectrochimica acta. Part A Molecular and biomolecular spectroscopy, 2010Co-Authors: Hongfei Cheng, Qinfu Liu, Jing Yang, Jinshan Zhang, Ray L. FrostAbstract:Mid-infrared (MIR) and near-infrared (NIR) spectroscopy have been compared and evaluated for differentiating Kaolinite, coal bearing Kaolinite and halloysite. Kaolinite, coal bearing Kaolinite and halloysite are the three relative abundant mineral of the kaolin group, especially in China. In the MIR spectra, the differences are shown in the 3000-3600 cm-1 between Kaolinite and halloysite. It can not be obviously differentiated the Kaolinite and halloysite, let alone Kaolinite and coal bearing Kaolinite. However, NIR, together with MIR, give us the sufficient evidence to differentiate the Kaolinite and halloysite, especially Kaolinite and coal bearing Kaolinite. There are obvious differences between Kaolinite and halloysite in the all range of their spectra, and it also show some difference between Kaolinite and coal bearing Kaolinite. Therefore, the reproducibility of measurement, signal to noise ratio and richness of qualitative information should be simultaneously considered for proper selection of a spectroscopic method for mineral analysis.
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Micro-structure differences in Kaolinite suspensions.
Journal of colloid and interface science, 2009Co-Authors: Marek Zbik, Ray L. FrostAbstract:SEM observations of the aqueous suspensions of Kaolinite from Birdwood (South Australia) and Georgia (USA) show noticeable differences in number of physical behaviour which has been explained by different micro-structure constitution. Birdwood Kaolinite dispersion gels are observed at very low solid loadings in comparison with Georgia KGa-1 Kaolinite dispersions which remain fluid at higher solids loading. To explain this behaviour, the specific particle interactions of Birdwood Kaolinite, different from interaction in Georgia Kaolinite have been proposed. These interactions may be brought about by the presence of nano-bubbles on clay crystal edges and may force clay particles to aggregate by bubble coalescence. This explains the predominance of stair step edge-edge like (EE) contacts in suspension of Birdwood Kaolinite. Such EE linked particles build long strings that form a spacious cell structure. Hydrocarbon contamination of colloidal Kaolinite particles and low aspect ratio are discussed as possible explanations of this unusual behaviour of Birdwood Kaolinite. In Georgia KGa-1 Kaolinite dispersions instead of EE contact between platelets displayed in Birdwood Kaolinite, most particles have edge-to-face (EF) contacts building a cardhouse structure. Such an arrangement is much less voluminous in comparison with the Birdwood Kaolinite cellular honeycomb structure observed previously in smectite aqueous suspensions. Such structural characteristics of KGa-1 Kaolinite particles enable higher solid volume fractions pulps to form before significantly networked gel consistency is attained.
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modification of low and high defect Kaolinite surfaces implications for Kaolinite mineral processing
Journal of Colloid and Interface Science, 2004Co-Authors: Ray L. Frost, Erzsébet Horváth, Eva Mako, Janos KristofAbstract:A comparison is made of the mechanochemical activation of three low and one high defect Kaolinites using a combination of X-ray diffraction, thermal analysis and DRIFT spectroscopy. The effect of mechanochemical alteration of the Kaolinites is greatest for the low defect Kaolinites. The effectiveness of the mechanochemical treatment is represented by the slope of the d(001)peakwidth-grinding time line. High defect Kaolinites are not significantly altered by the grinding treatment. The effect of mechanochemical treatment on peakwidth was independent of the presence of quartz; the quartz acts as an additional grinding medium. The effectiveness of the mechanochemical treatment depends on the crystallinity of the Kaolinite. Two processes are identified in the mechanochemical activation of the Kaolinite: first the delamination of Kaolinite appears to take place in the first hour of grinding and secondly a recombination process results in the reaggregation of the ground crystals. During this process proton hopping occurs and reaction to form water takes place. This water is then adsorbed and coordinated to surface active-sites created during mechanochemical treatment.
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Slow transformation of mechanically dehydroxylated Kaolinite to Kaolinite—an aged mechanochemically activated formamide-intercalated Kaolinite study
Thermochimica Acta, 2003Co-Authors: Ray L. Frost, Erzsébet Horváth, Janos Kristof, Eva Mako, Ákos RédeyAbstract:Formamide-intercalated high defect Kaolinite which was mechanochemically activated for periods of time up to 6 h has been aged for up to 1 year. These modified materials were studied using a combination of X-ray diffraction, thermal analysis and DRIFT spectroscopy. Ageing of the formamide-intercalated mechanochemically activated Kaolinite results in de-intercalation of the formamide and the de-intercalated Kaolinite returns to its original d-spacing. Thermal analysis shows that the temperature of dehydration and dehydroxylation increase by up to 30 °C. The temperature of the dehydroxylation of the aged samples was identical to that of the untreated Kaolinite. The DRIFT spectroscopy showed that the spectrum of the aged samples approached that of the untreated Kaolinite. The Kaolinite showed partial de-intercalation and the 6 h sample had reformed to a mineral resembling the untreated Kaolinite. The process of ageing the mechanochemically activated Kaolinite enabled the reformation of the Kaolinite.
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birdwood Kaolinite a highly ordered Kaolinite that is difficult to intercalate an xrd sem and raman spectroscopic study
Applied Clay Science, 2002Co-Authors: Ray L. Frost, J. Theo Kloprogge, S J Van Der Gaast, Marek Zbik, Gina N ParozAbstract:The intercalation of a highly ordered Kaolinite from Birdwood, South Australia, has been studied using a combination of electron microscopy, X-ray diffraction and Raman microscopy. Highly ordered Kaolinites normally intercalate easily and to a high degree. The Kaolinite under study was found to intercalate acetamide and formamide with difficulty and more than 18 days were required to achieve more than 20% intercalation. Further treatment did not improve the degree of intercalation past 60%. The difficulty of intercalation is attributed to the co-existence of two Kaolinite phases, a highly ordered (with a Hinckley index>1.3) and a highly disordered Kaolinite, the latter material appears to coat the highly ordered Kaolinite thereby limiting the intercalation. The presence of two forms of silica and a dickite were identified in the sample using X-ray diffraction.
J. Theo Kloprogge - One of the best experts on this subject based on the ideXlab platform.
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Birdwood Kaolinite: a highly ordered Kaolinite that is difficult to intercalate—an XRD, SEM and Raman spectroscopic study
Applied Clay Science, 2002Co-Authors: R.l. Frost, J. Theo Kloprogge, S J Van Der Gaast, Marek Zbik, Gina N ParozAbstract:The intercalation of a highly ordered Kaolinite from Birdwood, South Australia has been studied using a combination of electron microscopy, X-ray diffraction and Raman microscopy. Highly ordered Kaolinites normally intercalate easily and to a high degree. The Kaolinite under study was found to intercalate acetamide and formamide with difficulty and more than 18 days were required to achieve more than 20 % intercalation. Further treatment did not improve the degree of intercalation past 60 %. The difficulty of intercalation is attributed to the co-existence of two Kaolinite phases, a highly ordered (with a Hinckley index > 1.3) and a highly disordered Kaolinite, the latter material appears to coat the highly ordered Kaolinite thereby limiting the intercalation. The presence of two forms of silica and a dickite were identified in the sample using X-ray diffraction
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birdwood Kaolinite a highly ordered Kaolinite that is difficult to intercalate an xrd sem and raman spectroscopic study
Applied Clay Science, 2002Co-Authors: Ray L. Frost, J. Theo Kloprogge, S J Van Der Gaast, Marek Zbik, Gina N ParozAbstract:The intercalation of a highly ordered Kaolinite from Birdwood, South Australia, has been studied using a combination of electron microscopy, X-ray diffraction and Raman microscopy. Highly ordered Kaolinites normally intercalate easily and to a high degree. The Kaolinite under study was found to intercalate acetamide and formamide with difficulty and more than 18 days were required to achieve more than 20% intercalation. Further treatment did not improve the degree of intercalation past 60%. The difficulty of intercalation is attributed to the co-existence of two Kaolinite phases, a highly ordered (with a Hinckley index>1.3) and a highly disordered Kaolinite, the latter material appears to coat the highly ordered Kaolinite thereby limiting the intercalation. The presence of two forms of silica and a dickite were identified in the sample using X-ray diffraction.
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Separation of Adsorbed Formamide and Intercalated Formamide Using Controlled Rate Thermal Analysis Methodology
Langmuir, 2001Co-Authors: Ray L. Frost, Janos Kristof, Erzsébet Horváth, J. Theo KloproggeAbstract:Controlled rate thermal analysis (CRTA) has been used to separate adsorbed formamide from intercalated formamide in formamide-intercalated Kaolinites. This separation is achieved by removal of the sample at the end of the controlled isothermal desorption step. The temperature of this isothermal desorption is dependent on the use of open or closed crucibles in the thermal analysis unit but is independent of the formamide/water ratio. X-ray diffraction shows that the formamide-intercalated Kaolinite remains expanded after formamide desorption with a d(001) spacing of 10.09 A. Further heating to 300 °C results in the deintercalation of the formamide-intercalated Kaolinite. DRIFT spectroscopy shows differences between the infrared spectra of the adsorbed and formamide-intercalated Kaolinites. An intense band observed at 3629 cm-1 is attributed to the inner surface hydroxyls hydrogen bonded to the formamide. The adsorbed formamide-intercalated Kaolinites contain adsorbed water and show intensity in the 1705 cm...
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Raman spectroscopy of potassium acetate-intercalated Kaolinites at liquid nitrogen temperature.
Spectrochimica acta. Part A Molecular and biomolecular spectroscopy, 2001Co-Authors: Jolene M. Schmidt, J. Theo KloproggeAbstract:Raman microscopy has been used to study low and high defect Kaolinites and their potassium acetate intercalated complexes at 298 and 77 K. Raman spectroscopy shows significant differences in the spectra of the hydroxyl-stretching region of the two types of Kaolinites, which is also reflected in the spectroscopy of the hydroxyl-stretching region of the intercalation complexes. Additional bands to the normally observed Kaolinite hydroxyl stretching frequencies are observed for the low and high defect Kaolinites at 3605 and 3602 cm−1 at 298 K. Upon cooling to liquid nitrogen temperature, these bands are observed at 3607 and 3604 cm−1, thus indicating a weakening of the hydrogen bond formed between the inner surface hydroxyls and the acetate ion. Upon cooling to liquid nitrogen temperature, the frequency of the inner hydroxyls shifted to lower frequencies. Collection of Raman spectra at liquid nitrogen temperature did not give better band separation compared to the room temperature spectra as the bands increased in width and shifted closer together.
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Modification of Kaolinite Surfaces by Mechanochemical Treatment
Langmuir, 2001Co-Authors: Ray L. Frost, Janos Kristof, Erzsébet Horváth, Eva Mako, J. Theo KloproggeAbstract:Kaolinite surfaces were modified by grinding Kaolinite/quartz mixtures with mole fractions of 0.25 Kaolinite and 0.75 quartz for periods of time up to 4 h. X-ray diffraction shows the loss of intensity of the d(001) spacing with mechanical treatment resulting in the delamination of the Kaolinite. Thermogravimetric analyses show the Kaolinite surface is significantly modified and surface hydroxyls are replaced with water molecules. Changes in the molecular structure of the surface hydroxyls of the Kaolinite/quartz mixtures were followed by infrared spectroscopy. Kaolinite hydroxyls were lost after 2 h of grinding as evidenced by the decrease in intensity of the OH stretching vibrations at 3695 and 3619 cm-1 and the deformation modes at 937 and 915 cm-1. Changes in the surface structure of the OSiO units were reflected in the SiO stretching and OSiO bending vibrations. The decrease in intensity of the 1056 and 1034 cm-1 bands attributed to Kaolinite SiO stretching vibrations were concomitantly matched by the increase in intensity of additional bands at 1113 and 520 cm-1 ascribed to the new mechanically synthesized Kaolinite surface. Mechanochemical treatment of the Kaolinite results in a new surface structure.
Sabine Petit - One of the best experts on this subject based on the ideXlab platform.
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Kaolin intercalated by urea. Ceramic applications
Construction and Building Materials, 2016Co-Authors: Sahar Seifi, M.t. Diatta-dieme, Philippe Blanchart, Gisèle Laure Lecomte-nana, D. Kobor, Sabine PetitAbstract:Kaolinite–urea complexes were prepared with Kaolinite from KGa-1 kaolin by two techniques, mixingand ball-milling at room temperature in water. The intercalation degree was found to be 72% and 69% respectively. Urea-intercalated Kaolinite has potential applications in industry, since it change most of the chemical and thermal behaviors. Particularly, ion intercalation into Kaolinite structure changes the amount of reactive acidic and basic sites on the internal and external surfaces. In this study XRD patterns and infrared spectroscopy of Kaolinite–urea complexes confirm the intercalation of urea into Kaolinite by the expansion of the basal spacing of Kaolinite from 0.715 nm to 1.069 nm. The expansion of Kaolinite is due to entering urea into interlayers that confirms the occurrence of hydrogen bonding between urea and Kaolinite. Thermal analyses (TG, DSC and thermodilatometry) evidence changes in transformation temperatures of intercalated Kaolinite. The sintering densification is shifted to lower temperature and Kaolinite–urea complexes can be used in new ceramics for building with lower CO2 specific emission.
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Effect of the morphology of synthetic Kaolinites on their sorption properties
Journal of Colloid and Interface Science, 2015Co-Authors: Lei Lei Aung, Tertre Emmanuel, Sabine PetitAbstract:Natural Kaolinites often have a permanent charge due to mineralogical impurities preventing to link directly the morphology of the Kaolinite particle to a selectivity coefficient between two cations for edge sites. In this study, Kaolinites with no permanent charge were hydrothermally synthesized under different physicochemical conditions to obtain various morphologies (hexagon-shaped, more or less anisotropic). Na+ and H+ were chosen as the sorbed cations due to their ubiquitous presence in natural waters. For synthetic Kaolinites for which no swelling layer was detected, an experimental sorption isotherm between Na+ and H+ was obtained. Data were interpreted using a surface complexation model, containing no electrostatic term, by considering the specific surfaces of lateral sites and sorption site density identified by crystallography for the different faces presented in the samples ((0 1 0), (1 1 0), (1 1 0)). Selectivity coefficients between Na+ and H+ for all lateral sites characterizing a given morphology were calculated and validated in the [4-10] pH range, corresponding to the pH range for which dissolution can be considered negligible. The results showed that the Na+/H+ selectivity coefficient depends strongly on the particle morphology and that the sorption properties of Kaolinites cannot be obtained with good accuracy without a fine knowledge of the morphology of the particles.
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Crystal properties and energetics of synthetic Kaolinite
American Mineralogist, 2001Co-Authors: Claire-isabelle Fialips, Alexandra Navrotsky, Sabine PetitAbstract:Six Kaolinite [Al 2 Si 2 O 5 (OH) 4 ] samples were synthesized under different conditions of temperature, pressure, and pH from two different starting materials. Chemical composition and properties of the samples were characterized using classical methods (electron microprobe, atomic absorption spectrometry, X-ray diffraction, differential and thermal analyses, and Fourier transform infrared spectrometry). All synthetic Kaolinite samples contained various amounts of a boehmite impurity. The defect density was different for each Kaolinite, ranging from high to low. The enthalpy of formation of these Kaolinites at 25 °C was investigated by drop solution calorimetry into molten lead borate at 700 °C. All data were corrected for impurities. Whatever the synthesis conditions and the Kaolinite properties, the enthalpy of Kaolinite dissolution into molten lead borate at 700 °C and the standard enthalpy of Kaolinite formation from the oxides and from the elements at 25 °C are constant: 372.3 ±1.0 kJ/mol, −46.6 ±2.6 kJ/mol, and −4115.3 ±4.1 kJ/mol respectively. Using entropy data from the literature, the standard Gibbs free energy of Kaolinite formation from the elements at 25 °C is −3793.9 ±4.1 kJ/mol. This value is in excellent agreement with most of the literature data obtained for natural Kaolinites. Furthermore, the standard Gibbs free energy of Kaolinite formation at 25 °C and 1 atm is very close to that obtained using the same method for the San Juanito dickite, which is commonly used as a standard mineral, the value for Kaolinite being slightly more negative than the value for dickite. This trend is also true for all the temperature and pressure range of kaolin minerals occurrences. Thus, dickite is a metastable phase relative to Kaolinite, and Kaolinite seems to be thermodynamically more stable than dickite, as already proposed by DeLigny and Navrotsky (1999) and Anovitz et al. (1991). The natural occurrence of dickite must result from specific reaction paths and be controlled by kinetic factors.
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Influence of Synthesis pH on Kaolinite “Crystallinity” and Surface Properties
Clays and Clay Minerals, 2000Co-Authors: Claire-isabelle Fialips, Sabine Petit, Alain Decarreau, Daniel BeaufortAbstract:Hydrothermal syntheses were performed at various pH values and temperatures to induce variability in Kaolinite defect density. Temperature of synthesis ranged from 200 to 240°C, for 21 d. Initial pH at room temperature ranged from 0.5 to 14. The starting material was a hydrothermally treated gel, with an atomic Si/Al ratio of 0.93, partly transformed into Kaolinite. Kaolinite was obtained for a wide range of pH. Although no influence of temperature on “crystallinity” ( i.e. , defect density) was observed, the effect of pH was important. A continuous series was obtained from a low-defect Kaolinite, with high thermal stability and a hexagonal morphology for the most acidic final pH, to a high-defect Kaolinite, with low thermal stability and lath shape for the most basic final pH. These variations of Kaolinite properties appear related to the pH dependence of Kaolinite surface speciation. Increasing pH value results in increased cation adsorption on the Kaolinite external surfaces and increases in the elongation of particles.
Janos Kristof - One of the best experts on this subject based on the ideXlab platform.
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Kaolinite urea complexes obtained by mechanochemical and aqueous suspension techniques a comparative study
Journal of Colloid and Interface Science, 2009Co-Authors: Eva Mako, Erzsébet Horváth, Janos Kristof, Veronika VagvolgyiAbstract:Intercalation compounds of low- and high-defect Kaolinites have been prepared by direct reaction with urea aqueous solution as well as by co-grinding with urea in the absence of water (mechanochemical intercalation). The complexes formed were studied by X-ray diffraction, thermal analysis, DRIFT spectroscopy, and scanning electron microscopy. In aqueous solution the degree of intercalation for the low- and high-defect Kaolinites was found to be 77 and 65%, respectively. With mechanochemical intercalation, both Kaolinites were almost fully expanded after 1 h of grinding. Based on the results of DRIFT spectroscopy, a structural model for the bonding of urea to the siloxane surface is proposed. The Kaolinite-urea intercalation compounds produced by mechanochemical intercalation have crystallite sizes lower than those obtained by the aqueous solution method.
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modification of low and high defect Kaolinite surfaces implications for Kaolinite mineral processing
Journal of Colloid and Interface Science, 2004Co-Authors: Ray L. Frost, Erzsébet Horváth, Eva Mako, Janos KristofAbstract:A comparison is made of the mechanochemical activation of three low and one high defect Kaolinites using a combination of X-ray diffraction, thermal analysis and DRIFT spectroscopy. The effect of mechanochemical alteration of the Kaolinites is greatest for the low defect Kaolinites. The effectiveness of the mechanochemical treatment is represented by the slope of the d(001)peakwidth-grinding time line. High defect Kaolinites are not significantly altered by the grinding treatment. The effect of mechanochemical treatment on peakwidth was independent of the presence of quartz; the quartz acts as an additional grinding medium. The effectiveness of the mechanochemical treatment depends on the crystallinity of the Kaolinite. Two processes are identified in the mechanochemical activation of the Kaolinite: first the delamination of Kaolinite appears to take place in the first hour of grinding and secondly a recombination process results in the reaggregation of the ground crystals. During this process proton hopping occurs and reaction to form water takes place. This water is then adsorbed and coordinated to surface active-sites created during mechanochemical treatment.
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Slow transformation of mechanically dehydroxylated Kaolinite to Kaolinite—an aged mechanochemically activated formamide-intercalated Kaolinite study
Thermochimica Acta, 2003Co-Authors: Ray L. Frost, Erzsébet Horváth, Janos Kristof, Eva Mako, Ákos RédeyAbstract:Formamide-intercalated high defect Kaolinite which was mechanochemically activated for periods of time up to 6 h has been aged for up to 1 year. These modified materials were studied using a combination of X-ray diffraction, thermal analysis and DRIFT spectroscopy. Ageing of the formamide-intercalated mechanochemically activated Kaolinite results in de-intercalation of the formamide and the de-intercalated Kaolinite returns to its original d-spacing. Thermal analysis shows that the temperature of dehydration and dehydroxylation increase by up to 30 °C. The temperature of the dehydroxylation of the aged samples was identical to that of the untreated Kaolinite. The DRIFT spectroscopy showed that the spectrum of the aged samples approached that of the untreated Kaolinite. The Kaolinite showed partial de-intercalation and the 6 h sample had reformed to a mineral resembling the untreated Kaolinite. The process of ageing the mechanochemically activated Kaolinite enabled the reformation of the Kaolinite.
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Separation of Adsorbed Formamide and Intercalated Formamide Using Controlled Rate Thermal Analysis Methodology
Langmuir, 2001Co-Authors: Ray L. Frost, Janos Kristof, Erzsébet Horváth, J. Theo KloproggeAbstract:Controlled rate thermal analysis (CRTA) has been used to separate adsorbed formamide from intercalated formamide in formamide-intercalated Kaolinites. This separation is achieved by removal of the sample at the end of the controlled isothermal desorption step. The temperature of this isothermal desorption is dependent on the use of open or closed crucibles in the thermal analysis unit but is independent of the formamide/water ratio. X-ray diffraction shows that the formamide-intercalated Kaolinite remains expanded after formamide desorption with a d(001) spacing of 10.09 A. Further heating to 300 °C results in the deintercalation of the formamide-intercalated Kaolinite. DRIFT spectroscopy shows differences between the infrared spectra of the adsorbed and formamide-intercalated Kaolinites. An intense band observed at 3629 cm-1 is attributed to the inner surface hydroxyls hydrogen bonded to the formamide. The adsorbed formamide-intercalated Kaolinites contain adsorbed water and show intensity in the 1705 cm...
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Modification of Kaolinite Surfaces by Mechanochemical Treatment
Langmuir, 2001Co-Authors: Ray L. Frost, Janos Kristof, Erzsébet Horváth, Eva Mako, J. Theo KloproggeAbstract:Kaolinite surfaces were modified by grinding Kaolinite/quartz mixtures with mole fractions of 0.25 Kaolinite and 0.75 quartz for periods of time up to 4 h. X-ray diffraction shows the loss of intensity of the d(001) spacing with mechanical treatment resulting in the delamination of the Kaolinite. Thermogravimetric analyses show the Kaolinite surface is significantly modified and surface hydroxyls are replaced with water molecules. Changes in the molecular structure of the surface hydroxyls of the Kaolinite/quartz mixtures were followed by infrared spectroscopy. Kaolinite hydroxyls were lost after 2 h of grinding as evidenced by the decrease in intensity of the OH stretching vibrations at 3695 and 3619 cm-1 and the deformation modes at 937 and 915 cm-1. Changes in the surface structure of the OSiO units were reflected in the SiO stretching and OSiO bending vibrations. The decrease in intensity of the 1056 and 1034 cm-1 bands attributed to Kaolinite SiO stretching vibrations were concomitantly matched by the increase in intensity of additional bands at 1113 and 520 cm-1 ascribed to the new mechanically synthesized Kaolinite surface. Mechanochemical treatment of the Kaolinite results in a new surface structure.
Gina N Paroz - One of the best experts on this subject based on the ideXlab platform.
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birdwood Kaolinite a highly ordered Kaolinite that is difficult to intercalate an xrd sem and raman spectroscopic study
Applied Clay Science, 2002Co-Authors: Ray L. Frost, J. Theo Kloprogge, S J Van Der Gaast, Marek Zbik, Gina N ParozAbstract:The intercalation of a highly ordered Kaolinite from Birdwood, South Australia, has been studied using a combination of electron microscopy, X-ray diffraction and Raman microscopy. Highly ordered Kaolinites normally intercalate easily and to a high degree. The Kaolinite under study was found to intercalate acetamide and formamide with difficulty and more than 18 days were required to achieve more than 20% intercalation. Further treatment did not improve the degree of intercalation past 60%. The difficulty of intercalation is attributed to the co-existence of two Kaolinite phases, a highly ordered (with a Hinckley index>1.3) and a highly disordered Kaolinite, the latter material appears to coat the highly ordered Kaolinite thereby limiting the intercalation. The presence of two forms of silica and a dickite were identified in the sample using X-ray diffraction.
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Birdwood Kaolinite: a highly ordered Kaolinite that is difficult to intercalate—an XRD, SEM and Raman spectroscopic study
Applied Clay Science, 2002Co-Authors: R.l. Frost, J. Theo Kloprogge, S J Van Der Gaast, Marek Zbik, Gina N ParozAbstract:The intercalation of a highly ordered Kaolinite from Birdwood, South Australia has been studied using a combination of electron microscopy, X-ray diffraction and Raman microscopy. Highly ordered Kaolinites normally intercalate easily and to a high degree. The Kaolinite under study was found to intercalate acetamide and formamide with difficulty and more than 18 days were required to achieve more than 20 % intercalation. Further treatment did not improve the degree of intercalation past 60 %. The difficulty of intercalation is attributed to the co-existence of two Kaolinite phases, a highly ordered (with a Hinckley index > 1.3) and a highly disordered Kaolinite, the latter material appears to coat the highly ordered Kaolinite thereby limiting the intercalation. The presence of two forms of silica and a dickite were identified in the sample using X-ray diffraction
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Role of water in the intercalation of Kaolinite with hydrazine
Journal of colloid and interface science, 1998Co-Authors: Ray L. Frost, Janos Kristof, Gina N Paroz, J. Theo KloproggeAbstract:A low-defect Kaolinite of 7.18-A basal spacing was expanded upon intercalation with hydrazine. The 001 d-spacing was broad and the peak resolved into components at 10.28, 9.48, and 8.80 A. It was found that the ordered Kaolinite predominantly expanded to 9.48 A with 31.2% and 10.28 A with 38.0% of the total peak area. A high-defect Kaolinite showed expansion by hydrazine in identical steps with d-spacings of 10.27, 9.53, and 8.75 A. It is proposed that the intercalation of the Kaolinite by hydrazine occurs according to the orientation of the hydrazine molecule and that water plays an integral part in the process of Kaolinite expansion. For the hydrazine-intercalated Kaolinite, hydroxyl stretching bands attributed to water are observed at 3413, 3469, and 3599 cm-1 for the low-defect Kaolinite and at 3600 and 3555 cm-1 for the high-defect Kaolinite. Upon the exposure of the low-defect hydrazine-intercalated Kaolinite to air, an additional water band is observed at 3555 cm-1. Water bending modes are observed at 1578, 1598, 1612, 1627, 1650, and 1679 cm-1 for the hydrazine-intercalated low-defect Kaolinite and at 1578, 1598, 1613, 1627, 1652, and 1678 cm-1 for the hydrazine-intercalated high-defect Kaolinite. The intensities of these bands are a function of the exposure to air and measurement time. The 1650- and 1679 cm-1 bands increased in intensity as the intensity of the 1612 cm-1 band decreased. Even after exposure to air for 24 h, water remained in the Kaolinite interlayer space and only after heating was the water removed. The 1578, 1598, and 1612 cm-1 bands as well as the 1627 cm-1 band are attributed to (a) free or non-hydrogen-bonded water held in the interlayer spaces of the Kaolinite, (b) water in the hydration spheres of the hydrazine, and (c) adsorbed water on the Kaolinite surface. In Kaolinites additional bands at 1650 and 1679 cm-1 are attributed to water coordinated to the siloxane surface. Copyright 1998 Academic Press.