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Ray L Frost - One of the best experts on this subject based on the ideXlab platform.

  • Insight into the thermal decomposition of kaolinite intercalated with Potassium Acetate: an evolved gas analysis
    Journal of Thermal Analysis and Calorimetry, 2014
    Co-Authors: Hongfei Cheng, Qinfu Liu, Shuai Zhang, Ray L Frost
    Abstract:

    The thermal decomposition process of kaolinite–Potassium Acetate intercalation complex has been studied using simultaneous thermogravimetry coupled with Fourier-transform infrared spectroscopy and mass spectrometry (TG-FTIR-MS). The results showed that the thermal decomposition of the complex took place in four temperature ranges, namely 50–100, 260–320, 320–550, and 650–780 °C. The maximal mass losses rate for the thermal decomposition of the kaolinite–Potassium Acetate intercalation complex was observed at 81, 296, 378, 411, 486, and 733 °C, which was attributed to (a) loss of the adsorbed water, (b) thermal decomposition of surface-adsorbed Potassium Acetate (KAc), (c) the loss of the water coordinated to Potassium Acetate in the intercalated kaolinite, (d) the thermal decomposition of intercalated KAc in the interlayer of kaolinite and the removal of inner surface hydroxyls, (e) the loss of the inner hydroxyls, and (f) the thermal decomposition of carbonate derived from the decomposition of KAc. The thermal decomposition of intercalated Potassium Acetate started in the range 320–550 °C accompanied by the release of water, acetone, carbon dioxide, and acetic acid. The identification of pyrolysis fragment ions provided insight into the thermal decomposition mechanism. The results showed that the main decomposition fragment ions of the kaolinite–KAc intercalation complex were water, acetone, carbon dioxide, and acetic acid. TG-FTIR-MS was demonstrated to be a powerful tool for the investigation of kaolinite intercalation complexes. It delivers a detailed insight into the thermal decomposition processes of the kaolinite intercalation complexes characterized by mass loss and the evolved gases.

  • Mechanism of dehydroxylation temperature decrease and high temperature phase transition of coal-bearing strata kaolinite intercalated by Potassium Acetate
    Journal of colloid and interface science, 2012
    Co-Authors: Hongfei Cheng, Qinfu Liu, Zhang Zhiliang, Qian Zhang, Xiaonan Cui, Ray L Frost
    Abstract:

    The thermal decomposition and dehydroxylation process of coal-bearing strata kaolinite-Potassium Acetate intercalation complex (CSKK) has been studied using X-ray diffraction (XRD), infrared spectroscopy (IR), thermal analysis, mass spectrometric analysis and infrared emission spectroscopy. The XRD results showed that the Potassium Acetate (KAc) have been successfully intercalated into coal-bearing strata kaolinite with an obvious basal distance increase of the first basal peak, and the positive correlation was found between the concentration of intercalation regent KAc and the degree of intercalation. As the temperature of the system is raised, the formation of KHCO(3), KCO(3) and KAlSiO(4), which is derived from the thermal decomposition or phase transition of CSKK, is observed in sequence. The IR results showed that new bands appeared, the position and intensities shift can also be found when the concentration of intercalation agent is raised. The thermal analysis and mass spectrometric analysis results revealed that CSKK is stable below 300°C, and the thermal decomposition products (H(2)O and CO(2)) were further proved by the mass spectrometric analysis. A comparison of thermal analysis results of original coal-bearing strata kaolinite and its intercalation complex gives new discovery that not only a new mass loss peak is observed at 285 °C, but also the temperature of dehydroxylation and dehydration of coal bearing strata kaolinite is decreased about 100 °C. This is explained on the basis of the interlayer space of the kaolinite increased obviously after being intercalated by KAc, which led to the interlayer hydrogen bonds weakened, enables the dehydroxylation from kaolinite surface more easily. Furthermore, the possible structural model for CSKK has been proposed, with further analysis required in order to prove the most possible structures.

  • Mid-infrared and near-infrared spectroscopic study of kaolinite-Potassium Acetate intercalation complex
    Journal of Molecular Structure, 2011
    Co-Authors: Jinshan Zhang, Hongfei Cheng, Qinfu Liu, Ray L Frost
    Abstract:

    Abstract Mid-infrared (MIR) and near-infrared (NIR) spectroscopy have been used to elucidate the molecular structure of Potassium Acetate intercalated kaolinite and to determine the structural changes of kaolinite through intercalation. Based on analysis of the features and assignment for bands of MIR spectra, the NIR spectra provide the significant differences and the obvious structural change between kaolinite and the kaolinite-KAc intercalation complex. Detailed analysis of the NIR region is performed by comparing the first overtone (2 ν OH ) and combination ( ν  +  δ ) OH bands with the fundamental stretching ( ν ) and bending ( δ ) vibrations. The NIR spectrum of the kaolinite-KAc intercalation complex shows decrease after intercalation in the intensities of the structural OH vibrations overtone (7300–7000 cm −1 ) and the combination (4600–4300 cm −1 ) bands. Therefore, the application of the technique across the entire infrared region is expected to become more routine and extend its usefulness, and the reproducibility of measurement and richness of qualitative information should be simultaneously considered for proper selection of a spectroscopic method for molecular structural analysis.

  • thermal analysis and infrared emission spectroscopic study of kaolinite Potassium Acetate intercalate complex
    Journal of Thermal Analysis and Calorimetry, 2011
    Co-Authors: Hongfei Cheng, Jing Yang, Ray L Frost, Qinfu Liu, Zhiliang Zhang
    Abstract:

    The thermal behavior and decomposition of kaolinite–Potassium Acetate intercalation complex was investigated through a combination of thermogravimetric analysis and infrared emission spectroscopy. Three main changes were observed at 48, 280, 323, and 460 °C which were attributed to (a) the loss of adsorbed water, (b) loss of the water coordinated to Acetate ion in the layer of kaolinite, (c) loss of Potassium Acetate in the complex, and (d) water through dehydroxylation. It is proposed that the Potassium Acetate intercalation complex is stability except heating at above 300 °C. The infrared emission spectra clearly show the decomposition and dehydroxylation of the kaolinite intercalation complex when the temperature is raised. The dehydration of the intercalation complex is followed by the loss of intensity of the stretching vibration bands at region 3600–3200 cm−1. Dehydroxylation is followed by the decrease in intensity in the bands between 3695 and 3620 cm−1. Dehydration is completed by 400 °C and partial dehydroxylation by 650 °C. The inner hydroxyl group remained until around 700 °C.

  • Infrared spectroscopic study of halloysite-Potassium Acetate intercalation complex
    Journal of Molecular Structure, 2011
    Co-Authors: Hongfei Cheng, Jinshan Zhang, Jing Yang, Qinfu Liu, Ray L Frost
    Abstract:

    Abstract Mid-infrared (MIR) and near-infrared (NIR) spectroscopy have been used to study the molecular structure of halloysite and Potassium Acetate intercalated halloysite and to determine the structural changes of halloysite through intercalation. The MIR spectra show all fundamental vibrations including the hydroxyl units, basic aluminosilicate framework and water molecules in the structure of halloysite and its intercalation complex. Comparison between halloysite and halloysite-Potassium Acetate intercalation complex shows almost all bands observed for halloysite are also observed for halloysite-Potassium Acetate intercalation complex apart from bands observed in the 1700–1300 cm −1 region, but with differences in band intensity. However, NIR spectra, based on MIR spectra, provide sufficient evidence to analyze the structural changes of halloysite through intercalation. There are obvious differences between halloysite and halloysite-Potassium Acetate intercalation complex in all spectral ranges. Therefore, the reproducibility of measurement and richness of qualitative information should be simultaneously considered for proper selection of a spectroscopic method for molecular structural analysis.

Hongfei Cheng - One of the best experts on this subject based on the ideXlab platform.

  • Insight into the thermal decomposition of kaolinite intercalated with Potassium Acetate: an evolved gas analysis
    Journal of Thermal Analysis and Calorimetry, 2014
    Co-Authors: Hongfei Cheng, Qinfu Liu, Shuai Zhang, Ray L Frost
    Abstract:

    The thermal decomposition process of kaolinite–Potassium Acetate intercalation complex has been studied using simultaneous thermogravimetry coupled with Fourier-transform infrared spectroscopy and mass spectrometry (TG-FTIR-MS). The results showed that the thermal decomposition of the complex took place in four temperature ranges, namely 50–100, 260–320, 320–550, and 650–780 °C. The maximal mass losses rate for the thermal decomposition of the kaolinite–Potassium Acetate intercalation complex was observed at 81, 296, 378, 411, 486, and 733 °C, which was attributed to (a) loss of the adsorbed water, (b) thermal decomposition of surface-adsorbed Potassium Acetate (KAc), (c) the loss of the water coordinated to Potassium Acetate in the intercalated kaolinite, (d) the thermal decomposition of intercalated KAc in the interlayer of kaolinite and the removal of inner surface hydroxyls, (e) the loss of the inner hydroxyls, and (f) the thermal decomposition of carbonate derived from the decomposition of KAc. The thermal decomposition of intercalated Potassium Acetate started in the range 320–550 °C accompanied by the release of water, acetone, carbon dioxide, and acetic acid. The identification of pyrolysis fragment ions provided insight into the thermal decomposition mechanism. The results showed that the main decomposition fragment ions of the kaolinite–KAc intercalation complex were water, acetone, carbon dioxide, and acetic acid. TG-FTIR-MS was demonstrated to be a powerful tool for the investigation of kaolinite intercalation complexes. It delivers a detailed insight into the thermal decomposition processes of the kaolinite intercalation complexes characterized by mass loss and the evolved gases.

  • Mechanism of dehydroxylation temperature decrease and high temperature phase transition of coal-bearing strata kaolinite intercalated by Potassium Acetate
    Journal of colloid and interface science, 2012
    Co-Authors: Hongfei Cheng, Qinfu Liu, Zhang Zhiliang, Qian Zhang, Xiaonan Cui, Ray L Frost
    Abstract:

    The thermal decomposition and dehydroxylation process of coal-bearing strata kaolinite-Potassium Acetate intercalation complex (CSKK) has been studied using X-ray diffraction (XRD), infrared spectroscopy (IR), thermal analysis, mass spectrometric analysis and infrared emission spectroscopy. The XRD results showed that the Potassium Acetate (KAc) have been successfully intercalated into coal-bearing strata kaolinite with an obvious basal distance increase of the first basal peak, and the positive correlation was found between the concentration of intercalation regent KAc and the degree of intercalation. As the temperature of the system is raised, the formation of KHCO(3), KCO(3) and KAlSiO(4), which is derived from the thermal decomposition or phase transition of CSKK, is observed in sequence. The IR results showed that new bands appeared, the position and intensities shift can also be found when the concentration of intercalation agent is raised. The thermal analysis and mass spectrometric analysis results revealed that CSKK is stable below 300°C, and the thermal decomposition products (H(2)O and CO(2)) were further proved by the mass spectrometric analysis. A comparison of thermal analysis results of original coal-bearing strata kaolinite and its intercalation complex gives new discovery that not only a new mass loss peak is observed at 285 °C, but also the temperature of dehydroxylation and dehydration of coal bearing strata kaolinite is decreased about 100 °C. This is explained on the basis of the interlayer space of the kaolinite increased obviously after being intercalated by KAc, which led to the interlayer hydrogen bonds weakened, enables the dehydroxylation from kaolinite surface more easily. Furthermore, the possible structural model for CSKK has been proposed, with further analysis required in order to prove the most possible structures.

  • Mid-infrared and near-infrared spectroscopic study of kaolinite-Potassium Acetate intercalation complex
    Journal of Molecular Structure, 2011
    Co-Authors: Jinshan Zhang, Hongfei Cheng, Qinfu Liu, Ray L Frost
    Abstract:

    Abstract Mid-infrared (MIR) and near-infrared (NIR) spectroscopy have been used to elucidate the molecular structure of Potassium Acetate intercalated kaolinite and to determine the structural changes of kaolinite through intercalation. Based on analysis of the features and assignment for bands of MIR spectra, the NIR spectra provide the significant differences and the obvious structural change between kaolinite and the kaolinite-KAc intercalation complex. Detailed analysis of the NIR region is performed by comparing the first overtone (2 ν OH ) and combination ( ν  +  δ ) OH bands with the fundamental stretching ( ν ) and bending ( δ ) vibrations. The NIR spectrum of the kaolinite-KAc intercalation complex shows decrease after intercalation in the intensities of the structural OH vibrations overtone (7300–7000 cm −1 ) and the combination (4600–4300 cm −1 ) bands. Therefore, the application of the technique across the entire infrared region is expected to become more routine and extend its usefulness, and the reproducibility of measurement and richness of qualitative information should be simultaneously considered for proper selection of a spectroscopic method for molecular structural analysis.

  • thermal analysis and infrared emission spectroscopic study of kaolinite Potassium Acetate intercalate complex
    Journal of Thermal Analysis and Calorimetry, 2011
    Co-Authors: Hongfei Cheng, Jing Yang, Ray L Frost, Qinfu Liu, Zhiliang Zhang
    Abstract:

    The thermal behavior and decomposition of kaolinite–Potassium Acetate intercalation complex was investigated through a combination of thermogravimetric analysis and infrared emission spectroscopy. Three main changes were observed at 48, 280, 323, and 460 °C which were attributed to (a) the loss of adsorbed water, (b) loss of the water coordinated to Acetate ion in the layer of kaolinite, (c) loss of Potassium Acetate in the complex, and (d) water through dehydroxylation. It is proposed that the Potassium Acetate intercalation complex is stability except heating at above 300 °C. The infrared emission spectra clearly show the decomposition and dehydroxylation of the kaolinite intercalation complex when the temperature is raised. The dehydration of the intercalation complex is followed by the loss of intensity of the stretching vibration bands at region 3600–3200 cm−1. Dehydroxylation is followed by the decrease in intensity in the bands between 3695 and 3620 cm−1. Dehydration is completed by 400 °C and partial dehydroxylation by 650 °C. The inner hydroxyl group remained until around 700 °C.

  • Infrared spectroscopic study of halloysite-Potassium Acetate intercalation complex
    Journal of Molecular Structure, 2011
    Co-Authors: Hongfei Cheng, Jinshan Zhang, Jing Yang, Qinfu Liu, Ray L Frost
    Abstract:

    Abstract Mid-infrared (MIR) and near-infrared (NIR) spectroscopy have been used to study the molecular structure of halloysite and Potassium Acetate intercalated halloysite and to determine the structural changes of halloysite through intercalation. The MIR spectra show all fundamental vibrations including the hydroxyl units, basic aluminosilicate framework and water molecules in the structure of halloysite and its intercalation complex. Comparison between halloysite and halloysite-Potassium Acetate intercalation complex shows almost all bands observed for halloysite are also observed for halloysite-Potassium Acetate intercalation complex apart from bands observed in the 1700–1300 cm −1 region, but with differences in band intensity. However, NIR spectra, based on MIR spectra, provide sufficient evidence to analyze the structural changes of halloysite through intercalation. There are obvious differences between halloysite and halloysite-Potassium Acetate intercalation complex in all spectral ranges. Therefore, the reproducibility of measurement and richness of qualitative information should be simultaneously considered for proper selection of a spectroscopic method for molecular structural analysis.

J. Theo Kloprogge - One of the best experts on this subject based on the ideXlab platform.

  • Raman spectroscopy of Potassium Acetate‐intercalated kaolinites over the temperature range 25–300,°C
    Journal of Raman Spectroscopy, 2001
    Co-Authors: Ray L Frost, Erzsébet Horváth, Janos Kristof, J. Theo Kloprogge
    Abstract:

    Raman spectra of the hydroxyl-stretching region of Potassium Acetate-intercalated kaolinite were obtained under an atmosphere of both air and nitrogen using a thermal stage over the temperature range 25–300 °C. At 25 °C, an additional band at 3606 cm−1 attributed to the inner surface hydroxyl hydrogen bonded to the Acetate ion is observed with a concomitant loss of intensity in the bands attributed to the inner surface hydroxyls. Heating the intercalated complex to 50 °C results in two hydroxyl-stretching wavenumbers at 3594 and 3604 cm−1. At 100 °C, the bands shift to 3600 and 3613 cm−1. At temperatures from 100 to 300 °C, bands are observed in similar positions. Upon cooling in air to 25 °C, the Acetate-bonded inner surface hydroxyl stretching wavenumber shifts back to 3606 cm−1. Upon heating the intercalated kaolinite to 300 °C under an atmosphere of nitrogen and upon cooling the Acetate-bonded inner surface hydroxyl stretching wavenumber is observed at 3601 cm−1. Upon cooling to 150 °C and subsequently to 25 °C, two bands are observed at 3611 and 3600 cm−1. Upon rehydration, the hydroxyl stretching wavenumber returns to 3606 cm−1. The changes in the Raman spectra of the hydroxyl-stretching region during dehydration and rehydration are reversible. When the Potassium Acetate-intercalated kaolinite is heated to 300 °C and cooled to 25 °C, the inner-hydroxyl band is observed at 3630 cm−1. The shift in the wavenumber of the inner hydroxyl band is attributed to the insertion of the Potassium ion in the ditrigonal cavity of the siloxane layer. Copyright © 2001 John Wiley & Sons, Ltd.

  • Raman spectroscopy of Potassium Acetate-intercalated kaolinites at liquid nitrogen temperature.
    Spectrochimica acta. Part A Molecular and biomolecular spectroscopy, 2001
    Co-Authors: Ray L Frost, Janos Kristof, Jolene M. Schmidt, J. Theo Kloprogge
    Abstract:

    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.

  • Modification of the hydroxyl surface of Potassium Acetate intercalated halloysite between 25 and 300 °C
    American Mineralogist, 2000
    Co-Authors: Ray L Frost, Éva Makó, Janos Kristof, J. Theo Kloprogge
    Abstract:

    Changes in the hydroxyl surfaces of Potassium Acetate-intercalated halloysite were studied over ambient to predehydroxylation temperature range using a combination of X-ray diffraction and Raman spectroscopy. XRD shows that the halloysite is completely expanded to 13.80 A. Upon heating the intercalation complex to 50 °C under nitrogen, two expanded phases are observed with d -spacings of 11.47 and 8.95 A. Upon thermal treatment, the 11.47 A phase is stable in both the heating and cooling cycles. The ~9.0 A phase undergoes an expansion at 100 °C to 9.2 A. Upon exposure to air, the intercalated kaolinite returns to a 13.80 A phase. The completely intercalated halloysite showed a band at 3602 cm −1 attributed to the inner surface hydroxyl hydrogen bonded to the Acetate ion together with bands at 3620 and 3695 cm −1 assigned to the inner hydroxyl and the inner surface hydroxyls, which do not react with the Acetate. Mild heating of the intercalation complex to 50 °C caused a rearrangement of the surface structure with Raman bands being observed at 3606 and 3597 cm −1 . Further thermal treatment at 100 °C caused these bands to shift to 3615 and 3601 cm −1 . At the predehydroxylation temperature for Potassium Acetate intercalated halloysite (300 °C) two bands were observed at 3602 and 3612 cm −1 . Above this temperature no hydroxyls are spectroscopically evident. Upon cooling to room temperature, the Raman spectra of the hydroxyl surfaces are altered with two bands observed at 3604 and 3596 cm −1 .

  • Rehydration and Phase Changes of Potassium Acetate-Intercalated Halloysite at 298 K
    Journal of Colloid and Interface Science, 2000
    Co-Authors: Ray L Frost, Janos Kristof, Erzbeth Horvath, J. Theo Kloprogge
    Abstract:

    Abstract The kinetics of rehydration of Potassium Acetate-intercalated halloysite are slow as determined by X-ray diffraction. Compared with the rehydration of Potassium Acetate-intercalated kaolinite where rehydration takes 20 min, the rehydration of the halloysite–intercalation complex takes 4 h. X-ray diffraction shows the halloysite with an initial d(001) spacing of 7.13 A expands to 13.97 A with the insertion of the Potassium Acetate through intercalation. Upon heating to 250°C, two expanded phases with d(001) spacings of 11.84 and 9.80 A are observed which upon cooling to 25°C become 11.72 and 8.98 A. Upon exposure to air, multiple expanded phases are observed. The molecular structure of the Potassium Acetate-intercalated halloysite during cooling from 250°C and upon rehydration has also been studied using Raman microscopy. Raman spectroscopy shows that although the halloysites have been completely expanded, intercalation is incomplete as evidenced by the intensity of the inner surface hydroxyl band at 3695 cm−1. Thermal treatment shifts the band attributed to the inner hydroxyl at 3620 cm−1 to 3632 cm−1 at 250°C, which upon cooling returns to the starting frequency. The interaction between the Acetate and the inner surface hydroxyls is observed by the hydroxyl stretching frequency of 3605 cm−1. Upon dehydration the band shifts to 3599 cm−1. The observation of multiple expanded phases of halloysite during rehydration is strongly supported by the changes in the bands associated with the inserting Acetate ion. Two C–C and two C=O stretching vibrations are observed. It is proposed that the Acetate inserts into the halloysite layers with two different molecular structures.

  • Rehydration of Potassium Acetate-intercalated kaolinite at 298 K
    Langmuir, 2000
    Co-Authors: Ray L Frost, Janos Kristof, J. Theo Kloprogge, Erzbeth Horvath
    Abstract:

    The rehydration of Potassium Acetate-intercalated kaolinite has been followed using a combination of X-ray diffraction and Raman microscopy. Dehydration of the fully expanded Potassium Acetate-intercalated kaolinite with initial d(001) spacing of 13.88 angstrom, in an atmosphere of nitrogen, shows the presence of three expanded kaolinite phases with d(001) spacings of 11.47, 9.6, and 9.2 angstrom. X-ray diffraction shows the existence of six expanded phases after one minute of rehydration with d spacings of 14.13, 11.56, 11.04, 9.88, 8.90, and 8.55 angstrom. Rehydration is rapid with the intercalation complex rehydrating in less than 21 min. Raman spectroscopy shows hydroxyl stretching bands at 3632 cm assigned to the inner hydroxyl and at 3601 cm attributed to the inner surface hydroxyl hydrogen bonded to the Acetate ion when the intercalation complex is heated to 300°C under an atmosphere of nitrogen. The position of the inner hydroxyl band is observed at 3630 cm in the 298 K spectra, providing the intercalated kaolinite is not exposed to air. Phase changes of the intercalation complex are determined using the changes in intensity of the inner surface hydroxyl stretching bands. Phase changes are also observed through changes in intensity of the CqqO, C-C, and OCO Raman modes.

Kazuya Minato - One of the best experts on this subject based on the ideXlab platform.

  • Potassium Acetate catalyzed acetylation of wood reaction rates at low temperatures
    Wood Science and Technology, 2009
    Co-Authors: Eiichi Obataya, Kazuya Minato
    Abstract:

    Spruce wood blocks were acetylated in the presence of Potassium Acetate (KAc) at 20, 40, 60, 80 and 120°C. At 20°C, the weight percent gain (WPG) due to the KAc-catalyzed acetylation reached 20% in 18 days, whereas that due to pyridine-catalyzed acetylation did not exceed 8%. The hygroscopicity and dimensional stability of the KAc-acetylated wood were the same as those of conventionally acetylated wood at the same WPG, irrespective of reaction temperature. These facts suggest that the KAc enables simplified acetylation of wood at room temperature. The activation energy (Ea) of the KAc-acetylation in the lower temperature range (20–40°C, 121–131 kJ/mol) was comparable to that of the acetylation of wood meal (140–146 kJ/mol). It was speculated that diffusion became a minor factor at reduced reaction rates in the lower temperature range, thus requiring a greater Ea.

  • Potassium Acetate-catalyzed acetylation of wood at low temperatures I: simplified method using a mixed reagent
    Journal of Wood Science, 2009
    Co-Authors: Eiichi Obataya, Kazuya Minato
    Abstract:

    Ezomatsu wood blocks were acetylated in a mixture of acetic anhydride and acetic acid containing excess Potassium Acetate (KAc). The mixture method enabled rapid acetylation at 120°C: a 20% weight gain (weight percent gain; WPG) was achieved within 30 min while the WPG did not exceed 18% after 120 min of conventional uncatalyzed acetylation. At 40°C, however, a satisfactory WPG was not achieved with the mixture method because both the wood swelling and KAc concentration in the reagent solution were limited at that temperature. In addition, the antiswelling efficiency attained by the mixture method was irregularly low, probably because of nonuniform reaction involving shrinkage of the cell lumina. These results suggest that the mixture method is not advantageous for low-temperature acetylation, whereas it enables simple and rapid acetylation at high temperature.

  • Potassium Acetate-catalyzed acetylation of wood: extraordinarily rapid acetylation at 120°C
    Wood Science and Technology, 2008
    Co-Authors: Eiichi Obataya, Kazuya Minato
    Abstract:

    The catalytic effect of Potassium Acetate (KAc) on wood acetylation was investigated. Spruce wood specimens were impregnated with KAc and then heated in acetic anhydride at 120°C. The degree of acetylation was evaluated by the weight percent gain (WPG). In the presence of KAc, the reaction time to achieve a 20% WPG decreased by a factor of 200: 2 min was required in the KAc-catalyzed acetylation, while the uncatalyzed acetylation required at least 5 h. The hygroscopicity and dimensional stability of acetylated wood depended on the WPG irrespective of the treatment methods. This fact proved that KAc had no adverse influence on the dimensional stability of acetylated wood. As KAc is a cheap, water-soluble and non-toxic salt it can be a useful catalyst for the extraordinarily rapid acetylation of wood.

  • Potassium Acetate catalyzed acetylation of wood extraordinarily rapid acetylation at 120 c
    Wood Science and Technology, 2008
    Co-Authors: Eiichi Obataya, Kazuya Minato
    Abstract:

    The catalytic effect of Potassium Acetate (KAc) on wood acetylation was investigated. Spruce wood specimens were impregnated with KAc and then heated in acetic anhydride at 120°C. The degree of acetylation was evaluated by the weight percent gain (WPG). In the presence of KAc, the reaction time to achieve a 20% WPG decreased by a factor of 200: 2 min was required in the KAc-catalyzed acetylation, while the uncatalyzed acetylation required at least 5 h. The hygroscopicity and dimensional stability of acetylated wood depended on the WPG irrespective of the treatment methods. This fact proved that KAc had no adverse influence on the dimensional stability of acetylated wood. As KAc is a cheap, water-soluble and non-toxic salt it can be a useful catalyst for the extraordinarily rapid acetylation of wood.

Éva Makó - One of the best experts on this subject based on the ideXlab platform.

  • Water-mediated Potassium Acetate intercalation in kaolinite as revealed by molecular simulation
    Journal of molecular modeling, 2014
    Co-Authors: Zoltán Ható, Éva Makó, Tamás Kristóf
    Abstract:

    Molecular simulations are suitable tools to study the adsorption and intercalation of molecules in clays. In this work, a recently proposed thermodynamically consistent force field for inorganic compounds (INTERFACE, Heinz H, Lin TJ, Mishra RK, Emami FS (2013) Langmuir 29:1754–1765), which enables accurate simulations of inorganic–organic interfaces, was tested for a two-sheet type clay mineral. All-atom NpT molecular dynamics simulations were used to describe the characteristics (basal spacing, loading, molecular orientation) of some intercalate complexes of kaolinite with Potassium Acetate and the results were compared with the available experimental data. The most probable structural configurations of the kaolinite/Potassium Acetate intercalate complexes were determined from the simulations. Our examinations confirmed some supposed (single- or double-layered) arrangements of guest molecules. The need of interlayer water in the intercalate complex, which can be produced by the basic synthesis procedure in air atmosphere, was verified.

  • Kaolinite-Potassium Acetate and halloysite-Potassium Acetate complexes prepared by mechanochemical, solution and homogenization techniques: a comparative study
    Clay Minerals, 2014
    Co-Authors: Éva Makó, A. Kovács, Erzsébet Horváth, J. Kristóf
    Abstract:

    Kaolinite- and halloysite-Potassium Acetate complexes were synthesized by co-grinding with solid Potassium Acetate (mechanochemical intercalation). The efficiency of mechanochemical intercalation was compared to the intercalation in solution and by homogenization. The effects of ageing and grinding parameters (grinding time, sample:grinding body mass ratio (SGMR), rotational speed) and the humidity on the intercalation were studied. The degree of intercalation increased exponentially with ageing of the samples prepared by mechanochemical and homogenization techniques. For the mechanochemical and homogenization techniques the required amount of Potassium Acetate per gram of kaolin (∼0.4 g/g) was two orders of magnitude lower than that for the solution intercalation (78.6 g/g). The highest degree of intercalation (86%) and the lowest structural deformation were achieved by the mechanochemical method (¼ h of co-grinding with 1:2 SGMR at 300 rpm), followed by 16 h ageing at 57% relative humidity.

  • simulation assisted evidence for the existence of two stable kaolinite Potassium Acetate intercalate complexes
    Journal of Colloid and Interface Science, 2010
    Co-Authors: Éva Makó, Gábor Rutkai, Tamás Kristóf
    Abstract:

    Recent molecular simulation findings with several kaolinite intercalate complexes raised the question of the existence of more than one stable state, which has not been confirmed by experimental observations yet. Kaolinite/Potassium Acetate intercalate complexes were synthesized and examined by X-ray diffraction, and a molecular simulation study was performed for the system. Consistent with the suggestion from the simulations, an additional stable basal spacing was found experimentally at d(001)=1.168nm besides the well-known one at d(001)=1.403nm.

  • Simulation-assisted evidence for the existence of two stable kaolinite/Potassium Acetate intercalate complexes.
    Journal of colloid and interface science, 2010
    Co-Authors: Éva Makó, Gábor Rutkai, Tamás Kristóf
    Abstract:

    Recent molecular simulation findings with several kaolinite intercalate complexes raised the question of the existence of more than one stable state, which has not been confirmed by experimental observations yet. Kaolinite/Potassium Acetate intercalate complexes were synthesized and examined by X-ray diffraction, and a molecular simulation study was performed for the system. Consistent with the suggestion from the simulations, an additional stable basal spacing was found experimentally at d(001)=1.168nm besides the well-known one at d(001)=1.403nm.

  • A DRIFT spectroscopic study of Potassium Acetate intercalated mechanochemically activated kaolinite
    Spectrochimica acta. Part A Molecular and biomolecular spectroscopy, 2003
    Co-Authors: Ray L Frost, Éva Makó, Janos Kristof, Erzsébet Horváth
    Abstract:

    Kaolinite has been mechanochemically activated by dry grinding for periods of time up to 10 h. The kaolinite was then intercalated with Potassium Acetate and the changes in the structure followed by DRIFT spectroscopy. Intercalation of the kaolinite with Potassium Acetate is difficult and only the layers, which remain hydrogen bonded, are intercalated. The mechanochemical activation of the kaolinite may be followed by the loss of intensity of the hydroxyl-stretching vibrations. The intensity of the 3695 and 3619 cm−1 bands reach a minimum after 10 h of grinding. The observation of a band at 3602 cm−1 is indicative of the intercalation of the kaolinite with Potassium Acetate. The degree of intercalation decreases with mechanochemical treatment. The effect of exposure of the intercalated mechanochemically activated kaolinite to moist air results in de-intercalation. The effect of the mechanochemical treatment is loss of layer stacking, which prevents the intercalation of the kaolinite.