Thermal Analysis of Ion-Exchanged Montmorillonite

Webb, Steven W.; Stanley, D. A.; Scheiner, Bernard J.

doi:10.1080/02726358608906447

Cited by 8 publications

(7 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The 8H 2 O:4CO 2 system shows stronger secondary O–H peaks denoting a formation of second hydration. The closest Ca–O CO2 interaction is found in the Q-1W of the 10H 2 O:4CO 2 system, with approximately 1 contact within 3.0 Å …”

Section: Results and Disussionmentioning

confidence: 90%

“…The pVDOS of clay, H 2 O, and CO 2 are shown in Figure (b). The low-frequency region between 0 and 1200 cm –1 is dominated by Si–O–Si or Si–O–Al bending modes (∼450 cm –1 ) and the Si–O stretching mode (∼950 cm –1 ) . These molecular motions are likely to obscure any cage-rattling CO 2 motion (∼50 cm –1 ) under supercritical conditions, ,, the IR active CO 2 bending mode (∼600 cm –1 ), and the water librations (∼700 cm –1 ). , The weak band at ∼1550 cm –1 corresponds to the H 2 O bending mode, and the double band at ∼3500 cm –1 corresponds to the symmetric and asymmetric stretch of H 2 O.…”

Section: Results and Disussionmentioning

confidence: 99%

See 1 more Smart Citation

Microstructural Response of Variably Hydrated Ca-rich Montmorillonite to Supercritical CO₂

Lee

McGrail

Glezakou

2014

Environ. Sci. Technol.

105

View full text Add to dashboard Cite

First-principles molecular dynamics simulations were carried out to explore the mechanistic and thermodynamic ramifications of the exposure of variably hydrated Ca-rich montmorillonites to supercritical CO2 and CO2-SO2 mixtures under geologic storage conditions. In sub- to single-hydrated systems (≤ 1W), CO2 intercalation causes interlamellar expansion of 8-12%, while systems transitioning to 2W may undergo contraction (∼ 7%) or remain almost unchanged. When compared to ∼2W hydration state, structural analysis of the ≤ 1W systems, reveals more Ca-CO2 contacts and partial transition to vertically confined CO2 molecules. Infrared spectra and projected vibrational frequency analysis imply that intercalated Ca-bound CO2 are vibrationally constrained and contribute to the higher frequencies of the asymmetric stretch band. Reduced diffusion coefficients of intercalated H2O and CO2 (10(-6)-10(-7) cm(2)/s) indicate that Ca-montmorillonites in ∼ 1W hydration states can be more efficient in capturing CO2. Simulations including SO2 imply that ∼ 0.66 mmol SO2/g clay can be intercalated without other significant structural changes. SO2 is likely to divert H2O away from the cations, promoting Ca-CO2 interactions and CO2 capture by further reducing CO2 diffusion (10(-8) cm(2)/s). Vibrational bands at ∼ 1267 or 1155 cm(-1) may be used to identify the chemical state (oxidation states +4 or +6, respectively) and the fate of sulfur contaminants.

show abstract

Section: Results and Disussionmentioning

confidence: 90%

Section: Results and Disussionmentioning

confidence: 99%

Microstructural Response of Variably Hydrated Ca-rich Montmorillonite to Supercritical CO₂

Lee

McGrail

Glezakou

2014

Environ. Sci. Technol.

105

View full text Add to dashboard Cite

show abstract

“…Once the bulk interlayer water is removed during dehydration, the remaining H 2 O molecules become organized around the interlayer cations in a fashion and number dependent on the cation's hydration energy (Salles et al, 2015), expressed as the cation's hydration enthalpy (Table 1). The larger the absolute value of the cation hydration enthalpy (see Table 1 for an explanation of ΔH o ), the lower the probability for the cation to bind directly to the smectite's siloxane surface, the stronger the interaction between water molecules and the interlayer cation, and, therefore, the greater the energy that is required to remove any remaining strongly bound water (Webb et al, 1986).…”

Section: Dehydrationmentioning

confidence: 99%

Thermal Analysis and Thermal Reactions of Smectites: a Review of Methodology, Mechanisms, and Kinetics

Derkowski

Kuligiewicz

2022

Clays and clay miner.

View full text Add to dashboard Cite

Smectites are a group of minerals traditionally analyzed by thermal methods due to their exceptionally large adsorbed-water contents and the presence of OH groups, which makes them unique among all common soil- and rock-forming minerals. The dehydration reaction of smectite is a low-temperature endothermic effect that ends typically below 200°C. Although the removal of bulk interlayer water requires activation energy (Ea) of just above 30 kJ/mol, the removal of the last few H2O molecules attached strongly to interlayer cations requires Ea > 100 kJ/mol. Dehydroxylation is the loss of structural OH groups that proceeds as evolution of H2O molecules out of the smectite structure and occurs in the 300–900°C range. In trioctahedral species, dehydroxylation is combined with recrystallization and proceeds usually at > 700°C. In dioctahedral species, the temperature of dehydroxylation is controlled by the type of octahedral vacancy, having trans-vacant and cis-vacant distinguished by the boundary at ~ 600°C, and by the octahedral cation–OH bond strength, following the order Mg > Al > Fe. The Ea of dehydroxylation correlates linearly with the temperature of maximum dehydroxylation; from > 170 kJ/mol for Cs+-exchanged beidellite and nontronite, through ~ 300 kJ/mol in Mg-rich montmorillonite, to > 500 kJ/mol in trioctahedral saponite. Dehydration and dehydroxylation of smectites can be accompanied by a number of other phenomena, such as dehydrogenation or defluorination. At high temperatures, smectite amorphization and recrystallization occurs. Unless amorphized and/or recrystallized, smectites can undergo rehydration and rehydroxylation, which are opposite reactions to dehydration and dehydroxylation, respectively. This review discusses the details of the above-mentioned thermal reactions of smectites, focusing on thermogravimetric methods, evolved gas analysis, and structural alterations. Factors affecting the accuracy and precision of thermal analysis of smectite are discussed along with examples of best laboratory practices. The paper also provides the most recent description and critical evaluation of smectite reaction kinetics.

show abstract

Section: Hydrogels For Piv Channel Materialsmentioning

confidence: 99%

“…PEG with low molecular weight (200 to 20,000 g/mol [ 79 ]) is an organic epoxide with the formula (C 2 H 4 O) n [ 80 ]. The polymer is known as PEO for higher molecular weights up to 5 million g/mol [ 79 ]. Because of its low toxicity, PEG is one of the most used synthetic hydrogels in biomedical applications [ 73 ].…”

Section: Hydrogels For Piv Channel Materialsmentioning

confidence: 99%

A Review on Novel Channel Materials for Particle Image Velocimetry Measurements—Usability of Hydrogels in Cardiovascular Applications

Winkler

Kuhn

Hentschel

et al. 2022

Gels

View full text Add to dashboard Cite

Particle image velocimetry (PIV) is an optical and contactless measurement method for analyzing fluid blood dynamics in cardiovascular research. The main challenge to visualization investigated in the current research was matching the channel material’s index of refraction (IOR) to that of the fluid. Silicone is typically used as a channel material for these applications, so optical matching cannot be proven. This review considers hydrogel as a new PIV channel material for IOR matching. The advantages of hydrogels are their optical and mechanical properties. Hydrogels swell more than 90 vol% when hydrated in an aqueous solution and have an elastic behavior. This paper aimed to review single, double, and triple networks and nanocomposite hydrogels with suitable optical and mechanical properties to be used as PIV channel material, with a focus on cardiovascular applications. The properties are summarized in seven hydrogel groups: PAMPS, PAA, PVA, PAAm, PEG and PEO, PSA, and PNIPA. The reliability of the optical properties is related to low IORs, which allow higher light transmission. On the other hand, elastic modulus, tensile/compressive stress, and nominal tensile/compressive strain are higher for multiple-cross-linked and nanocomposite hydrogels than single mono-cross-linked gels. This review describes methods for measuring optical and mechanical properties, e.g., refractometry and mechanical testing.

show abstract

Thermal Analysis of Ion-Exchanged Montmorillonite

Cited by 8 publications

References 6 publications

Microstructural Response of Variably Hydrated Ca-rich Montmorillonite to Supercritical CO₂

Microstructural Response of Variably Hydrated Ca-rich Montmorillonite to Supercritical CO₂

Thermal Analysis and Thermal Reactions of Smectites: a Review of Methodology, Mechanisms, and Kinetics

A Review on Novel Channel Materials for Particle Image Velocimetry Measurements—Usability of Hydrogels in Cardiovascular Applications

Contact Info

Product

Resources

About

Thermal Analysis of Ion-Exchanged Montmorillonite

Cited by 8 publications

References 6 publications

Microstructural Response of Variably Hydrated Ca-rich Montmorillonite to Supercritical CO2

Microstructural Response of Variably Hydrated Ca-rich Montmorillonite to Supercritical CO2

Thermal Analysis and Thermal Reactions of Smectites: a Review of Methodology, Mechanisms, and Kinetics

A Review on Novel Channel Materials for Particle Image Velocimetry Measurements—Usability of Hydrogels in Cardiovascular Applications

Contact Info

Product

Resources

About

Microstructural Response of Variably Hydrated Ca-rich Montmorillonite to Supercritical CO₂

Microstructural Response of Variably Hydrated Ca-rich Montmorillonite to Supercritical CO₂