Effect of thermal dehydration and rehydration on Na-magadiite structure

Moura, Aline O.; Prado, Alexandre G.S.

doi:10.1016/j.jcis.2008.10.032

Cited by 38 publications

(30 citation statements)

References 38 publications

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“…A weak third mass step of 1.2 %, at temperatures above 200 °C, was assigned to the dehydroxylation of the silicate layers that occurred at a maximum temperature of 280 °C ( Figure 5(A)). This feature was similar to that reported for the magadiite materials [4,3,36].…”

Section: Thermal Gravimetric Analysis (Tga)supporting

confidence: 90%

“…are summarized in Table 2. The Na-magadiite exhibited a SBET value of 35 m 2 /g, close to that reported for similar materials and other layered silicates such as kanemite and kenyaite [33,36,47]. The modification with C16TMA cations led to a decrease of the SBET value from 25 m 2 /g for the partially exchanged magadiite The SEM micrographs of the starting magadiite and the resulting organo-magadiites are presented in Figure 5.…”

Section: Microtextural Studies and Specific Surface Areassupporting

confidence: 78%

“…The Na-magadiite exhibited a basal spacing of 1.54 nm, close to that reported in the literature [2,35,36], when it was reacted with an initial surfactant loading of 0.40 mM and a broad reflection corresponding to 3.10 nm was obtained, indicating a partial exchange of the Na-magadiite occurred. The intensity of the broad reflection at 3.10 nm was improved by increasing the loading concentration of C16TMABr, and the pattern exhibited sharp reflections for a basal spacing of 3.10 nm.…”

supporting

confidence: 87%

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Application of Organo-Magadiites for the Removal of Eosin Dye from Aqueous Solutions: Thermal Treatment and Regeneration

Kooli¹,

Liu²,

Abouddi³

et al. 2018

Preprint

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Na-magadiite exchanged with cetyl-trimethylammonium cations provided organophilic silicate materials that allowed the effective removal of the acidic dye "eosin". The organic cations were intercalated into the interlayer spacing of the layered silicate via an exchange reaction between the organic cations from their bromide salt and the solid Na-magadiite at room temperature. Different techniques were used to characterize the effect of the initial concentration of the surfactant on the structure of the organo-magadiites. The C, H, N analysis indicated that a maximum of 2 organic cations of 1.03 mmol/g was achieved at initial concentrations higher than 0.25 mmol/g and was accompanied by an expansion of the basal spacing of 3.15 nm, with a tilted angle of 64.5° to the silicate layers. The conformation of the organic surfactants was probed using solid-state 13 C, finding mainly the trans conformation similar to that of the starting cetyl trimethylammonium bromide salt (C16TMABr).Thermal gravimetric analysis was carried out to study the thermal stability of the resulting organo-magadiites. The intercalated surfactants started to decompose at 200 °C, with a mass loss percentage of 8 % to 25 %, depending on the initial loading of the surfactant, and was accompanied by a decrease of the basal spacing from 3.20 nm to 2.51 nm, as deduced from the in situ X-ray diffraction studies. At temperatures below 220 °C, an expansion of the basal spacing from 3.15 to 3.35 nm occurred.These materials were used as a removal agent for the anionic dye "eosin". The maximum amount of the dye removed was related to the organic cation content and to the initial concentration of eosin, with an improvement from 2.5 mg/g to 98 mg/g. This value decreased when the organo-magadiite was preheated at temperatures above 200 °C. The regeneration tests indicated that an 85 % removal efficiency was maintained after 6 cycles of use for the organo-magadiites.

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Section: Thermal Gravimetric Analysis (Tga)supporting

confidence: 90%

Section: Microtextural Studies and Specific Surface Areassupporting

confidence: 78%

supporting

confidence: 87%

See 1 more Smart Citation

Application of Organo-Magadiites for the Removal of Eosin Dye from Aqueous Solutions: Thermal Treatment and Regeneration

Kooli¹,

Liu²,

Abouddi³

et al. 2018

Preprint

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“…In addition, a basal spacing of 1.54 nm corresponding to the d001 reflection was detected as shown in Fig. 1 [34]. The average crystallite size was 16.63 nm and the lattice strain was 0.0416 as deduced from scherrer equation [35].…”

Section: Characterization Of the Sncmmentioning

confidence: 82%

Application of Synthetic Layered Sodium Silicate Magadiite Nanosheets for Environmental Remediation of Methylene Blue Dye in Water

Mokhtar

2017

Preprint

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Abstract:The removal of methylene blue (MB) dye from water was investigated using synthetic nano-clay magadiite (SNCM). SNCM was synthesized by hydrothermal treatment under autogenous pressure. A rosette-shaped single mesoporous magadiite phase with 16.63 nm average crystallite size and 33mBET-surface area was recorded. The adsorption results indicated the pronounced affinity of the SNCM to the MB dye molecules which reached adsorption uptake of 20.0 mg MB dye/g of SNCM. The elimination of MB dye by the SNCM was kinetically and thermodynamically considered; a pseudo second order kinetic model was attained, and a spontaneous, chemical, and exothermic in nature was verified.

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“…This is an expected result since the removal of the water molecules of crystallization is relatively easier than that of water molecules in ionic structure. That is, dehydration mechanism can be given as follows; Na2(B4O5(OH)4).3H2O Na2(B4O5(OH)4).0.75H2O + 2.25H2O (8) Na2(B4O5(OH)4).0.75H2O Na2B4O7 + 2.75 H2O (9) This result deviates by 25 % from the general belief of the ratio of 3:2 [6]. It is attributed to the fact that the removal of the crystal water is getting more difficult as it decreases in the crystal.…”

Section: Kinetics Modelingmentioning

confidence: 99%

Kinetics of Borax Dehydration by Thermal Analysis

Akbay

Altıokka²

2017

ANADOLU UNIVERSITY JOURNAL OF SCIENCE AND TECHNOLOGY a - Applied Sciences and Engineering

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Anhydrous borax is an important industrial product obtained either from borax decahydrate or borax pentahydrate. The kinetics of dehydration of borax pentahydrate using TG and DTA techniques was studied. It was shown that 2.25 mole of the crystal water removes in the first step with zero order kinetics in the temperature range between 382 and 433 K. The removing of the remaining water was completed at 733 K with the second order reaction in the second steps. Arrhenius form of reaction rate constant for step 1 and 2 were also determined. respectively, where T is absolute temperature in K.The total activation energy calculated from Coats-Redfern method was found to be 147.3 kJ/mol. It was also found that this value is in a good agreement with those calculated from Kissinger and Doyle methods.

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Effect of thermal dehydration and rehydration on Na-magadiite structure

Cited by 38 publications

References 38 publications

Application of Organo-Magadiites for the Removal of Eosin Dye from Aqueous Solutions: Thermal Treatment and Regeneration

Application of Organo-Magadiites for the Removal of Eosin Dye from Aqueous Solutions: Thermal Treatment and Regeneration

Application of Synthetic Layered Sodium Silicate Magadiite Nanosheets for Environmental Remediation of Methylene Blue Dye in Water

Kinetics of Borax Dehydration by Thermal Analysis

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