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1.
Ali. E. I. Elkhalifah Saikat Maitra M. Azmi Bustam T. Murugesan 《Journal of Thermal Analysis and Calorimetry》2012,110(2):765-771
Different cationic forms of montmorillonite, mainly K-, Na-, Ca- and Mg-montmorillonites were intercalated in this study via ion exchange process with mono-, di-, and triethanolammonium cations. The developed samples were characterized by TG, XRD, and CHNS techniques. Thermogravimetric study of ammonium-montmorillonites shows three thermal transition steps, which are attributable to the volatilization of the physically adsorbed water and dehydration, followed by the decomposition of the intercalated ammonium cations and dehydroxylation of the structural water of the modified clay, respectively, while untreated and cationic forms of montmorillonite showed only two decomposition steps. The type of ammonium cation has affected both desorption temperature (Position) and the amount of the adsorbed water (intensity). XRD results show a stepwise change in the crystallographic spacings of montmorillonite with the molar mass of ammonium cation, reflecting a change in the structure of the clay. CHNS data confirm the intercalation of ammonium cations into the interlayer space of montmorillonite and corroborate the effect of the molar mass of ammonium cation on the amount adsorbed by the clay. 相似文献
2.
R. Janík E. Jóna M. Pajtá?ová D. Ondru?ová P. Lizák V. Pavlík R. Durny S. C. Mojumdar 《Journal of Thermal Analysis and Calorimetry》2012,108(3):915-919
The influence of the 2-, 3-, and 4-OH phenols on the type of interaction with Co-exchanged montmorillonite and thermal properties of these materials were studied. The results of XRD, IR, and thermal (TG, DTG) analysis show that organic species are intercalated into the interlayer space of montmorillonite. Thermal decomposition in the temperature interval 20?C700?°C of studied samples with 2- and 3-hydroxyphenol proceeds in three steps (the release of adsorbed H2O molecules, combustion/desorption of protonated hydroxy phenols and dehydroxylation), while the sample with 4-hydroxyphenol decompose in four steps (the new peak at ~222?°C corresponds to directly coordinated organic species). The effect of different position of the hydroxyl groups on the phenol ring on the thermal decomposition is evident. 相似文献
3.
Effect of surfactant agent upon the structure of montmorillonite 总被引:2,自引:2,他引:0
The modification of sodium montmorillonite (MMT) through the incorporation of amphiphilic octadecylammonium cations in various
concentrations (10–200% CEC) into the clay’s interlayer spaces has been studied. High resolution thermogravimetric analysis
shows that the thermal decomposition of modified montmorillonite occurs in three steps. The first step of mass loss is related
to dehydration of adsorbed water and water hydrating metal cations such as Na+. The second step of mass loss is attributed to the decomposition of surfactant. The third step is due to the loss of OH units
during the dehydroxylation of the montmorillonite. The conformation of the surfactant cations in the confined space of the
silicate galleries is investigated by X-ray diffraction analysis. These analyses are very important for any attempt to incorporate
the organomodified MMT particles into different media for various applications such as polymer nanocomposite preparation. 相似文献
4.
Summary High resolution thermogravimetric analysis has been used to study the thermal decomposition of montmorillonite modified with octadecyltrimethylammonium bromide. Thermal decomposition occurs in 4 steps.The first step of mass loss is observed from ambient to 100°C temperature range and is attributed to dehydration of adsorbed water. The second step of mass loss occurs between 87.9 to 135.5°C temperature range and is also attributed to dehydration of water hydrating metal cations such as Na+. The third mass loss occurs between 179.0 and 384.5°C; it is assigned to the loss of surfactant. The fourth step is ascribed to the loss of OH units due to dehydroxylation of the montmorillonite and takes place between 556.0 and 636.3°C temperature range. These TG steps are related to the arrangement of the surfactant molecules intercalating the montmorillonite. Changes in the basal spacing of the clay with surfactant are followed by X-ray diffraction. Thermal analysis provides an indication of the stability of the organo-clay. 相似文献
5.
6.
S. Šnircová E. Jóna R. Janík Ľ. Lajdová S. Lendvayová M. Loduhová V. Šutinská R. Durný P. Lizák S. C. Mojumdar 《Journal of Thermal Analysis and Calorimetry》2011,104(3):937-941
The influence of different steric properties of ethylenediamine (EDA), trimethylenediamine (TrMeEDA) and tetraethylenediamine
(TeMeEDA) on the type of interactions with Co(II)-exchanged montmorillonite and thermal decomposition of these materials were
studied. The results of X-ray diffraction (XRD), thermogravimetry (TG), derivative thermogravimetry (DTG) and spectral analysis
shows that the studied ethylenediamines are intercalated into the interlayer space of montmorillonite. Thermal decomposition
at 20–500 °C of studied samples with EDA proceeds in three steps (the release of chemosorbed amines, coordinated EDA and dehydroxylation)
while the sample with TrMeEDA and TeMeEDA in five steps (also release the protonated forms). The effect of different steric
properties of individual diamines is evident. 相似文献
7.
Longfei Lu Jingong Cai Ray L. Frost 《Journal of Thermal Analysis and Calorimetry》2010,100(1):141-144
Thermal analysis and differential thermal analysis offers a novel means of studying the desorption of acids such as stearic
acid from clay surfaces. Both adsorption and chemisorption can be distinguished through the differences in the temperature
of mass losses. Increased adsorption is achievable by adsorbing onto a surfactant adsorbed montmorillonite. Stearic acid sublimes
at 179 °C but when adsorbed upon montmorillonite sublimes at 207 and 248 °C. These mass loss steps are ascribed to the desorption
of the stearic acid on the external surfaces of the organoclays and from the de-chemisorption from the surfactant held in
the interlayer of the montmorillonite. 相似文献
8.
Characterization and thermal properties of Ni-exchanged montmorillonite with benzimidazole 总被引:1,自引:1,他引:0
E. Jóna M. Sapietová S. Šnircová M. Pajtášová D. Ondrušová V. Pavlík L’. Lajdová S. C. Mojumdar 《Journal of Thermal Analysis and Calorimetry》2008,94(1):69-73
Thermal analysis (TG, DTG), powder diffraction analysis (XRD) and infrared (IR) spectra were used to study of composition
and release of benzimidazole from Ni(II)-exchanged montmorillonite under heating. Diffraction analysis indicated that benzimidazole
molecules are intercalated into the interlayer space of montmorillonite. IR spectra and the analytical characteristics have
shown that different type of interactions of benzimidazole is connected with different reaction conditions (acid or neutral
solution). The release of benzimidazole from Ni(II)-montmorillonite under heating from studied samples proceeds in three distinct
steps. The first step can be assigned to the release of water molecules while the last (third) one corresponds to the lattice
dehydroxylation. The second step can be assigned to release of chemically bonded benzimidazole. 相似文献
9.
Marinkovic-Neducin R. P. Kiss E. E. Cukic T. Z. Obadovic D. Z. 《Journal of Thermal Analysis and Calorimetry》2004,78(1):307-321
The purified bentonite parent clay, fraction ≤; 2 mm of montmorillonite type, has been pillared by various polyhydroxy cations,
Al, AlFe and AlCu, using conventional pillaring methods. The thermal behavior of PILCs was investigated by combination of
X-ray diffraction (XRD), thermal analysis (DTA, TG) and low temperature N2 adsorption/desorption (LTNA). Thermal stability
of Al-, AlFe- and AlCu-PILC samples was estimated after isothermal pretreatment in static air on the temperatures 300, 500,
600 and 900°C. Crucial structural changes were not registered up to 600°C, but the fine changes in interlayer surrounding
and porous/microporous structure being obvious at lower temperatures, depending on the nature of the second pillaring ion.
AlFe-PILC showed higher thermal stability of the texture, the AlCu-PILC having lower values and lower thermal stability concerning
both overall texture and micropore surface and volume. Poorer thermal stability of AlCu-PILC sample at higher temperatures
was confirmed, the presence of Cu in the system contributing to complete destruction of aluminum silicate structure, by 'extracting'
aluminum in stabile spinel form.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
10.
Anne M. Garrido Pedrosa M. J. B. Souza A. O. S. Silva Dulce M. A. Melo A. S. Araujo 《Journal of Thermal Analysis and Calorimetry》2006,84(2):503-509
The study of the incorporation
of rare earth elements as additives in Y zeolites is a very interesting field
of research, mainly by its potential application as additives in catalytic
cracking process. In this work was studied the thermal and structural properties
of cerium, holmium and samarium supported on HZSM-12 zeolite. The obtained
materials were characterized by X-ray diffraction (XRD), infrared spectroscopy
(FTIR), nitrogen adsorption, thermogravimetry (TG/DTG), differential scanning
calorimetry (DSC) and differential thermal analysis (DTA). TG/DSC/DTA analyses
showed that the dehydration temperatures of RE/HZSM-12 zeolites (RE=Ce, Ho, Sm) increase in relation to pure HZSM-12.
The acid properties were investigated by pyridine thermo desorption via TG.
The results showed two events of mass loss attributed to elimination of pyridine
adsorbed on the weak+medium acid sites and on the strong acid sites. 相似文献
11.
X-ray diffraction has been used to study the changes in the surface properties of a montmorillonitic clay through the changes in the basal spacings of montmorillonite (SWy-2) and surfactant-intercalated organoclays. Variation in the d-spacing was found to be a step function of the surfactant concentration. High-resolution thermogravimetric analysis (HRTG) shows that the thermal decomposition of SWy-2-MMTs modified with the surfactant octadecyltrimethylammonium bromide takes place in four steps. A mass-loss step is observed at room temperature and is attributed to dehydration of adsorption water. A second mass-loss step is observed over the temperature range 87.9 to 135.5 degrees C and is also attributed to dehydration of water hydrating metal cations such as Na+. The third mass loss occurs from 178.9 to 384.5 degrees C and is assigned to a loss of surfactant. The fourth mass-loss step is ascribed to the loss of OH units through dehydroxylation over the temperature range 556.0 to 636.4 degrees C. A model is proposed in which, up to 0.4 CEC, a surfactant monolayer is formed between the montmorillonitic clay layers; up to 0.8 CEC, a lateral-bilayer arrangement is formed; and above 1.5 CEC, a pseudotrimolecular layer is formed, with excess surfactant adsorbed on the clay surface. 相似文献
12.
Mg-Al-CO_3与Zn-Al-CO_3水滑石热稳定性差异的研究 总被引:6,自引:0,他引:6
层状双金属氢氧化物( Layered double hydroxides,简称 LDHs)是一类近年来发展迅速的阴离子型粘土,又称水滑石,其组成通式为: [M? 1-xM? x(OH)2]x+ Ax/nn-mH2O,其中 M?是二价金属离子, M?是三价金属离子, An-是阴离子。这种材料是由相互平行的层板组成,层板带有永久正电荷;层间具有可交换的阴离子以维持电荷平衡。通过离子交换可在层间嵌入不同的基团,制备许多功能材料,被广泛用作催化剂、吸附剂及油田化学品等,已引起人们的关 注 [1~ 4]。有关 Mg-Al-CO3与 Zn-Al-CO3水滑石的合成及性能研究国内外已有大量报道 [1… 相似文献
13.
D. Malferrari Maria Franca Brigatti Angela Laurora L. Medici S. Pini 《Journal of Thermal Analysis and Calorimetry》2006,86(2):365-370
The thermal behavior
of montmorillonite and organically modified montmorillonite, both treated
with heavy metal cations [Cu(II), Cd(II) and Hg(II)], was characterized via
thermal analyses (TG, DTG and DTA) combined with evolved species gas mass
spectrometry (MS-EGA), and X-ray diffraction at in situ controlled temperature
(HTXRD). The reactions involving Cu(II)- and Cd(II)-montmorillonite samples
are mostly related to H2O and OH loss, unlike Hg(II)-montmorillonite,
where effects associated to Hg(II) loss are also present. Finally reactions
related to dehydration, dehydroxylation and to organic matter decomposition
can be observed in montmorillonite samples treated with cysteine. 相似文献
14.
Surfaces of a Wyoming SWy-2 sodium montmorillonite were modified using microwave radiation through intercalation with the cationic surfactants octadecyl-trimethyl ammonium bromide, dimethyldioctadecylammonium bromide, and methyl-tri-octadecyl ammonium bromide by an ion exchange mechanism. Changes in the surfaces and structure were characterized using X-ray diffraction (XRD), thermal analysis (TG) and infrared (IR) spectroscopy. Different configurations of surfactants within montmorillonite interlayer are proposed based on d(001) basal spacings. A range of surfactant molecular environments within the surface-modified montmorillonite are proposed based upon their thermal decomposition. IR spectroscopy using a smart endurance single bounce diamond attenuated total reflection (ATR) cell has been used to study the changes in the spectra of CH asymmetric and symmetric stretching modes of the surfactants to provide more information of the surfactant molecular configurations. 相似文献
15.
Cheng H Liu Q Cui X Zhang Q Zhang Z Frost RL 《Journal of colloid and interface science》2012,376(1):47-56
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. 相似文献
16.
Lingya Ma Qing Zhou Tian Li Qi Tao Jianxi Zhu Peng Yuan Runliang Zhu Hongping He 《Journal of Thermal Analysis and Calorimetry》2014,115(1):219-225
For combining the properties of organoclays and pillared clays, inorganic–organic clays have attracted much attention in recent years. In this study, Al Keggin cation pillared montmorillonites (Al-Mts) were first prepared and parts of Al-Mts were calcined at different temperatures (C-Al-Mts). The inorganic–organic montmorillonites were synthesized by intercalating Al-Mts and C-Al-Mts with the cationic surfactant, hexadecyltrimethyl ammonium bromide (HDTMAB). The products were characterized by X-ray diffraction, X-ray fluorescence, and simultaneous thermogravimetric analysis. For HDTMAB-modified uncalcined Al Keggin cation pillared montmorillonites (H-Al-Mts), the basal spacing increased with the increment of surfactant loading level, but the Al content of H-Al-Mts decreased simultaneously, indicating that the intercalated surfactant replaced some Al Keggin cations in the interlayer space. However, in the case of C-Al-Mts, the interlayer spaces could not be further expanded after surfactant modification, implying that the neighboring montmorillonite layers were “locked” by the aluminum pillars which were formed by dehydroxylation of Al Keggin cation pillars during thermal treatment. The thermal stability of HDTMAB-modified C-Al-Mts (H-C-Al-Mts) was much better than that of H-Al-Mts. The major mass loss of H-C-Al-Mts occurred at ca. 410 °C, corresponding to decomposition of intercalated surfactant cations. In contrast, H-Al-Mts displayed two mass loss temperatures at ca. 270 and 410 °C, corresponding to the evaporation of surfactant molecules and the decomposition of surfactant cations in the interlayer space, respectively. 相似文献
17.
R. Janík E. Jóna V. Pavlík P. Lizák S. C. Mojumdar 《Journal of Thermal Analysis and Calorimetry》2013,112(2):1083-1087
The influence of different steric and electronic properties of 2,5- and 3,5-dimethylphenols (2,5 and 3,5-DMP) on the type of interactions with Cobalt-exchanged montmorillonite (Co-MMT) was studied. The results of X-ray diffraction (XRD), IR-spectroscopy and thermal (TG, DTG) analysis show that phenol derivatives are intercalated into the interlayer space of montmorillonite. Thermal decomposition in the temperature interval 20–700 °C of Co-MMT with 3,5-DMP proceeds in four steps while Co-MMT with 2,5-DMP decompose only in three steps. These differences are connected with different acid–base interactions of individual phenol derivatives in the interlayer space of montmorillonite, which is in agreement with the results of IR-spectroscopy. 相似文献
18.
N. Voyer A. Soisnard Sara J. Palmer W. N. Martens R. L. Frost 《Journal of Thermal Analysis and Calorimetry》2009,96(2):481-485
Zn-Al hydrotalcites and Cu-Al hydrotalcites were synthesised by coprecipitation method and analysed by X-ray diffraction (XRD)
and thermal analysis coupled with mass spectroscopy. These methods provide a measure of the thermal stability of the hydrotalcite.
The XRD patterns demonstrate similar patterns to that of the reference patterns but present impurities attributed to Zn(OH)2 and Cu(OH)2. The analysis shows that the d003 peak for the Zn-Al hydrotalcite gives a spacing in the interlayer of 7.59 ? and the estimation
of the particle size by using the Debye-Scherrer equation and the width of the d003 peak is 590 ?. In the case of the Cu-Al
hydrotalcite, the d003 spacing is 7.57 ? and the size of the diffracting particles was determined to be 225 ?.
The thermal decomposition steps can be broken down into 4 sections for both of these hydrotalcites. The first step decomposition
below 100°C is caused by the dehydration of some water absorbed. The second stage shows two major steps attributed to the
dehydroxylation of the hydrotalcite. In the next stage, the gas CO2 is liberated over a temperature range of 150°C. The last reactions occur over 400°C and involved CO2 evolution in the decomposition of the compounds produced during the dehydroxylation of the hydrotalcite. 相似文献
19.
Sodium montmorillonite has been modified via cation exchange reaction using gemini surfactants. Montmorillonite modified by cetyltrimethyl ammonium bromide (CTAB) is used for comparation. Basal spacings and thermal stability of these organo-montmorillonite clays have been characterized using X-ray diffraction analysis and thermogravimetric analysis. The d(001) spacings of montmorillonite-Gemini14, montmorillonite-Gemini16, montmorillonite-Gemini18 can reach above 35 Å compared with the 23.66 Å of the montmorillonite-CTAB at 2.2CEC. The thermogravimetric analysis show four-step degradation which corresponds to residual water desorption, dehydration, followed by decomposition of the organic modifier and the dehydroxylation of the organo-montmorillonite. In addition, DTG enables two different structural arrangements of gemini surfactant molecules intercalating the montmorillonite to be proposed that is different from montmorillonite-CTAB. 相似文献
20.
Ni-exchanged montmorillonite with methyl-, dimethyl- and trimethylamine and their thermal properties
S. Šnircová E. Jóna L’. Lajdová V. Jorik M. Drábik M. Pajtášová D. Ondrušová S. C. Mojumdar 《Journal of Thermal Analysis and Calorimetry》2009,96(1):63-66
The influence of different steric properties of methylamine (MA), dimethylamine (DIMA) and trimethylamine (TRMA) on the type
of interactions with Ni-exchanged montmorillonite and thermal properties of these materials were studied. The results of diffraction,
spectral (IR) and thermal (TG, DTG) analysis show that MA, DIMA and TRMA are intercalated into the interlayer space of montmorillonite.
Thermal decomposition in the temperature interval 20–450°C of studied samples with MA and DIMA proceeds in three steps (the
release of chemisorbed amines, coordinated amines and alkylammonium cations) while the sample with TRMA decompose only in
two steps (the peak corresponds to the release of coordinated TRMA is absent). The effect of different steric properties of
individual amines is evident. 相似文献