Sorption of water vapour by M-montmorillonite (M = Na, Li, La)

AbstractThe effect of heating on the water sorption capacity of a La-saturated montmorillonite, La-Mt, has been investigated. Sodium and Li as exchangeable ions have also been included for comparative purposes. XPS of La-Mt shows no migration of La(III) from interlamellar positions to octahedral sites on heating at 300°C. The water adsorbed as a multilayer on the external surface of the montmorillonite has been subtracted from the total sorbed water. Although the c-spacing of La-Mt corresponds to a two-layer hydrate, in the relative humidity range from 30 to 70%, the interlamellar water amounts to only 70% of the value for a complete monolayer. Heating at 300°C for 24 h has no influence on the uptake of molecular water between the structural layers of the La-Mt. The average numbers of water molecules per exchangeable ion sorbed into the interlamellar spacing up to 50% r.h. are: 5(Na-Mt), 3(Li-Mt) and 13(La-Mt).

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Mechanochemical reactions of GaN-Al2O3 interface at the nanoasperity contact: Roles of crystallographic polarity and ambient humidity

Friction ◽

10.1007/s40544-021-0501-9 ◽

2021 ◽

Author(s):

Jian Guo ◽

Jian Gao ◽

Chen Xiao ◽

Lei Chen ◽

Linmao Qian

Keyword(s):

Underlying Mechanism ◽

Water Molecules ◽

Dangling Bond ◽

Activation Energy Barrier ◽

Surface Machining ◽

Environmental Humidity ◽

Relative Humidity Range ◽

Ultra Precision ◽

Humidity Range ◽

Mechanochemical Reactions

AbstractMechanochemical reactions of the GaN-Al2O3 interface offer a novel principle for scientific and technological merits in the micro-/nano-scale ultra-precision surface machining. In this work, the mechanochemical reactions on Ga- and N-faced GaN surfaces rubbed by the Al2O3 nanoasperity as a function of the environmental humidity were investigated. Experimental results indicate that the N-face exhibits much stronger mechanochemical removal over the relative humidity range of 20%–80% than the Ga-face. Increasing water molecules in environmental conditions significantly promotes the interfacial mechanochemical reactions and hence accelerates the atomic attrition on N-face. The hypothesized mechanism of the selective water-involved mechanochemical removal is associated with the dangling bond configuration, which affects the mechanically-stimulated chemical reactions via altering the activation energy barrier to form the bonding bridge across the sliding interface. These findings can enrich the understanding of the underlying mechanism of mechanochemical reactions at GaN-Al2O3 interface and a broad cognition for regulating the mechanochemical reactions widely existing in scientific and engineering applications.

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Etude structurale par diffraction des RX et spectroscopie IR des hydrates 10 et 8.4 Å de kaolinite

Journal of Applied Crystallography ◽

10.1107/s0021889899008602 ◽

1999 ◽

Vol 32 (5) ◽

pp. 968-976 ◽

Cited By ~ 5

Author(s):

S. Jemai ◽

A. Ben Haj Amara ◽

J. Ben Brahim ◽

A. Plançon

Keyword(s):

Water Molecule ◽

Octahedral Site ◽

Ammonium Fluoride ◽

Water Molecules ◽

X Ray Diffraction ◽

Tetrahedral Sheet ◽

X Ray ◽

Octahedral Sites ◽

Sheet Structure

Two hydrated kaolinites, characterized by 10 and 8.4 Å basal distances, were synthesized by treating the kaolinite KGa-1 with dimethyl sulfoxide (DMSO) and ammonium fluoride (NH4F). The X-ray diffraction study was based on a comparison between the experimental and calculated profiles. This study was conducted in two steps: firstly, the study of the 00lreflections enabled the determination of the stacking mode alongc*, the number of water molecules and their positions along the normal to the plane of the sheet structure; secondly, the study of thehkbands, withhand/ork≠ 0, enabled the determination of the stacking mode and the positions of the water molecules in the (a,b) plane. The 10 Å hydrated kaolinite is characterized by two water molecules per Al2Si2O5(OH)4unit, situated at 3 and 3.4 Å from the hydroxyl surface, over the octahedral sites. Two adjacent layers are translated with respect to each other, withT11= −0.38a− 0.37b+ 10n. The 8.4 Å hydrated kaolinite is characterized by one water molecule per Al2Si2O5(OH)4unit, situated at 2.4 Å from the hydroxyl surface and inserted between the vacant octahedral site and the ditrigonal cavity of the tetrahedral sheet. The corresponding interlayer shift isT11= −0.355a+ 0.35b+ 8.4n.

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Crystal structure of coalingite

Mineralogical Magazine ◽

10.1180/minmag.1971.038.295.02 ◽

1971 ◽

Vol 38 (295) ◽

pp. 286-294 ◽

Cited By ~ 27

Author(s):

J. Pastor-Rodriguez ◽

H. F. W. Taylor

Keyword(s):

Crystal Structure ◽

Single Crystal ◽

Water Molecules ◽

Structural Elements ◽

Structural Element ◽

X Ray ◽

Octahedral Sites ◽

Carbonate Ions ◽

Disordered Layer ◽

Ray Methods

SummaryThe crystal structure of coalingite (Mg10Fe2(OH)24(CO3)·2H2O) has been determined using single-crystal X-ray methods. The mineral is trigonal, with space group Rm, aH = 3·12, cH = 37·4 Å, Z = ½, and (0001) cleavage. The structure is of a layer type, and is based on a structural element about 12·5 Å thick in the c-direction and consisting of two brucite-like layers and one disordered layer containing carbonate ions and water molecules and resembling those in sjögrenite and pyroaurite. The unit cell comprises three of these structural elements stacked together in the c-direction. The Mg2+ and Fe3+ ions are randomly distributed among all the octahedral sites of the brucite-like layers. The structure closely resembles those of sjögrenite and pyroaurite, but has two brucite-like layers between each CO32−−H2O layer where these have one. There is a tendency to random interstratification, and the crystals appear to contain intergrown regions of brucite and of sjögrenite or pyroaurite. Coalingite-K probably has a similar structure, but with three brucite-like layers between each -H2O layer; its idealized formula is probably Mg16Fe2(OH)36(CO3).2H2O.

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R-Line Luminescence from Trace Amounts of Cr3+ in Aluminum Oxide and its Dependence on Sample Hydration

Applied Spectroscopy ◽

10.1366/000370202321274872 ◽

2002 ◽

Vol 56 (8) ◽

pp. 1055-1058 ◽

Cited By ~ 10

Author(s):

Chen Zuo ◽

Paul W. Jagodzinski

Keyword(s):

Aluminum Oxide ◽

Raman Spectra ◽

Laser Excitation ◽

Sample Surface ◽

Optical Spectra ◽

Water Molecules ◽

Commercial Products ◽

Degree Of Hydration ◽

Setting Reaction ◽

Octahedral Sites

The R-line luminescence is observed in the Raman spectra of α- and γ-Al2O3 with chromium concentrations of less than 1 ppm. The same signals were previously used to monitor the setting reaction of dental cements. With laser excitation <690 nm, the R-line luminescence can be observed in the optical spectra of most commercial products containing α-Al2O3. It is found that the intensities of R-line signals are related to the degree of hydration of the α-Al2O3 sample, which can be explained by the formation of additional octahedral sites for Cr3+ near the sample surface involving oxygen atoms from the Al2O3 matrix and from absorbed water molecules.

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One-bodied humidity and temperature sensor having advanced linearity at low and high relative humidity range

Sensors and Actuators B Chemical ◽

10.1016/s0925-4005(01)00611-6 ◽

2001 ◽

Vol 76 (1-3) ◽

pp. 322-326 ◽

Cited By ~ 41

Author(s):

Sekwang Park ◽

Jeongho Kang ◽

Jinsu Park ◽

Suhwan Mun

Keyword(s):

Relative Humidity ◽

Temperature Sensor ◽

High Relative Humidity ◽

Relative Humidity Range ◽

Humidity Range

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Boltzmann-Based Empirical Model to Calculate Volume Loss during Spirit Ageing

Beverages ◽

10.3390/beverages5040060 ◽

2019 ◽

Vol 5 (4) ◽

pp. 60

Author(s):

Noemí del Toro del Toro ◽

Fredy Fong Casas ◽

Julio Ayan Rial ◽

Maria Caridad Portuondo González ◽

Harold Crespo Sariol ◽

...

Keyword(s):

Boltzmann Equation ◽

Relative Humidity ◽

Quercus Alba ◽

Volume Loss ◽

Air Humidity ◽

White Oak ◽

The Boltzmann Equation ◽

Relative Humidity Range ◽

Two Parameters ◽

Humidity Range

The Boltzmann equation is applied to fit data of volume loss for evaporation (in %) during spirit ageing in northern white oak (Quercus Alba) standard barrels of 205 L (+/− 10 L) using a temperature and humidity controlled cellar. The Boltzmann equation satisfactory fitted to the experimental data of the volume loss against temperature at constant humidity. Two parameters of the Boltzmann equation showed a linear dependency on the relative humidity of the air, while the other two parameters exhibited a constant value independently of the air humidity. The found empirical mathematical model can be used to calculate the volume loss for evaporation of spirits (40% v/v of ethanol) during ageing in terms of relative humidity (range: 40%–95%) and temperature (range: 10–30 °C) with significant accuracy.

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Bioinspired stimuli-responsive multilayer film made of silk–titanate nanocomposites

Journal of Materials Chemistry C ◽

10.1039/c7tc00149e ◽

2017 ◽

Vol 5 (16) ◽

pp. 3924-3931 ◽

Cited By ~ 26

Author(s):

Elena Colusso ◽

Giovanni Perotto ◽

Yu Wang ◽

Marco Sturaro ◽

Fiorenzo Omenetto ◽

...

Keyword(s):

Relative Humidity ◽

Multilayer Structure ◽

Multilayer Film ◽

Stimuli Responsive ◽

Term Stability ◽

Long Term Stability ◽

Relative Humidity Range ◽

Responsive Behavior ◽

Humidity Range

A bioinspired multilayer film made of a new silk–titanate nanocomposite material, showing a humidity-responsive behavior, has been fabricated. The multilayer structure mimics the structure of the cuticle of the Hoplia coerulea beetle and shows long-term stability over a very large relative humidity range.

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Entomological Problems of Food Storage in Northern Nigeria

Bulletin of Entomological Research ◽

10.1017/s0007485300030649 ◽

1952 ◽

Vol 43 (1) ◽

pp. 111-144 ◽

Cited By ~ 50

Author(s):

R. W. Howe

Keyword(s):

Relative Humidity ◽

Moisture Content ◽

Food Storage ◽

Northern Nigeria ◽

Diurnal Range ◽

Relative Humidity Range ◽

The Mean ◽

Humidity Range

In Nigeria, shelled groundnuts are stored in sacks in covered warehouses and as pyramids in the open air. At the beginning of storage the nuts comprise approximately equal quantities of whole, split and broken nuts of a moisture content of 3·4 per cent. The sacks are exposed to direct hot sun whilst stacking.The mean monthly maximum shade temperature in Kano ranges from 101°F. in April to 85°F. in January and August and the mean monthly minimum from 75°F. in May to 56°F. in January. Monthly maximum relative humidities range from 100 per cent, in August and September to 45 per cent, in February, and the monthly minimum from 71 per cent, in August to 12 per cent, in February. The range of mean relative humidity is 81 per cent, in August and 18 per cent, in February. Rains fall between April and September, 70 per cent, falling in July and August. Heavy falls are recorded on about 25 days.Inside warehouses, the maximum monthly temperatures are 102°F. in May and 79°F. in January and February, and minimum temperatures are 81°F. in June, and 58°F. in February. In August the mean relative humidity range is 93 per cent, to 70 per cent. In December it is 34 per cent. to 20 per cent.Just under the roof of a warehouse and on the surface of pyramids the diurnal range is very large.

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The Conductance of Tetraalkylammonium Iodides in Aqueous Proline and Hydroxyproline Solutions

Zeitschrift für Naturforschung A ◽

10.1515/zna-1979-1014 ◽

1979 ◽

Vol 34 (10) ◽

pp. 1225-1229

Author(s):

B. Sesta ◽

C. La Mesa ◽

C. Cantale ◽

M. Vincenzini

Keyword(s):

Dielectric Constant ◽

Electrostatic Interactions ◽

Hydrophobic Interactions ◽

Molecular Water ◽

Water Molecules ◽

Destructive Effect ◽

Iodide Ions ◽

Tetraalkylammonium Ions ◽

Equivalent Conductance ◽

Tetrabutylammonium Iodide

Abstract The density, viscosity and dielectric constant of aqueous proline and hydroxyproline solutions have been determined at 25 °C. The results appear to indicate that the two aminoacids have a destructive effect on the molecular water aggregates. The equivalent conductance of tetramethylammonium iodide and tetrabutylammonium iodide in aqueous proline and hydroxyproline solutions has been measured at 25°C. The aminoacids increase the viscosity of the solutions and decrease the limiting equivalent conductance of the two electrolytes. Electrostatic interactions of the iodide ions with the water molecules and hydrophobic interactions of the tetraalkylammonium ions with the aminoacids also seem to affect the conductometric behaviour of the electrolytes.

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