Short-Chain alkylammonium montmorillonites and alcohols: gas adsorption and immersional wetting

AbstractShort-chain alkylammonium derivatives of montmorillonite (< 8 or 10 C atoms in the alkyl chain) adsorb alcohols in the micropores between the alkylammonium ions. The external surface area and the micropore volume are derived from comparison plots of ethanol and butanol adsorption isotherms. The micropore volume varies between ∼0 (decylammonium derivative) and 100µl/g (methylammonium derivative); the external surface area determined by ethanol and butanol gas adsorption is about 50 m2/g, and is almost independent of the alkyl chain length. In contact with the alcohols, the alkylammonium ions in the interlayer space remain in h1 or h2 arrangement (monolayers or bilayers of flat-lying alkylammonium ions); on the external surface they move into an upward position. The heat of immersion decreases strongly with increasing alkyl chain length to a minimum for decylammonium ions, the variation being very similar for ethanol, butanol, hexanol, octanol and decanol. Immersion in ethanol increases the external surface area at the expense of the internal surface area. In butanol and longer alcohols this area remains unchanged. The increase of the external surface is related mainly to changes in the less ordered regions around the core of the crystals which consists of coherent silicate layers. The heat of wetting is ∼ 110 mJ/m2 (external and internal surfaces). The integral enthalpy of adsorption of butanol, 40–50 kJ/mol, is independent of the alkyl chain length (nc ≤ 8).

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Plasma Catalysis: Distinguishing between Thermal and Chemical Effects

Catalysts ◽

10.3390/catal9020185 ◽

2019 ◽

Vol 9 (2) ◽

pp. 185 ◽

Cited By ~ 7

Author(s):

Guido Giammaria ◽

Gerard van Rooij ◽

Leon Lefferts

Keyword(s):

Gas Phase ◽

Surface Area ◽

Thermal Effects ◽

External Surface ◽

Plasma Chemistry ◽

Internal Surface ◽

Plasma Power ◽

External Surface Area ◽

Internal Surface Area ◽

Chemical Effects

The goal of this study is to develop a method to distinguish between plasma chemistry and thermal effects in a Dielectric Barrier Discharge nonequilibrium plasma containing a packed bed of porous particles. Decomposition of CaCO3 in Ar plasma is used as a model reaction and CaCO3 samples were prepared with different external surface area, via the particle size, as well as with different internal surface area, via pore morphology. Also, the effect of the CO2 in gas phase on the formation of products during plasma enhanced decomposition is measured. The internal surface area is not exposed to plasma and relates to thermal effect only, whereas both plasma and thermal effects occur at the external surface area. Decomposition rates were in our case found to be influenced by internal surface changes only and thermal decomposition is concluded to dominate. This is further supported by the slow response in the CO2 concentration at a timescale of typically 1 minute upon changes in discharge power. The thermal effect is estimated based on the kinetics of the CaCO3 decomposition, resulting in a temperature increase within 80 °C for plasma power from 0 to 6 W. In contrast, CO2 dissociation to CO and O2 is controlled by plasma chemistry as this reaction is thermodynamically impossible without plasma, in agreement with fast response within a few seconds of the CO concentration when changing plasma power. CO forms exclusively via consecutive dissociation of CO2 in the gas phase and not directly from CaCO3. In ongoing work, this methodology is used to distinguish between thermal effects and plasma–chemical effects in more reactive plasma, containing, e.g., H2.

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Influence of the external surface area of small crystallite zeolites on the micropore volume determination

Microporous and Mesoporous Materials ◽

10.1016/s1387-1811(98)00206-6 ◽

1998 ◽

Vol 25 (1-3) ◽

pp. 185-192 ◽

Cited By ~ 35

Author(s):

Eduardo Falabella Sousa-Aguiar ◽

Adilson Liebsch ◽

Beatriz C. Chaves ◽

Alexandre F. Costa

Keyword(s):

Surface Area ◽

External Surface ◽

Micropore Volume ◽

External Surface Area ◽

Volume Determination ◽

Small Crystallite

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Use of pressure manifestations following the water plasma expansion for phytomass disintegration

Water Science & Technology ◽

10.2166/wst.2013.041 ◽

2013 ◽

Vol 67 (8) ◽

pp. 1695-1700 ◽

Cited By ~ 30

Author(s):

Josef Maroušek ◽

Jason Tai Hong Kwan

Keyword(s):

Gas Adsorption ◽

External Surface ◽

Anaerobic Fermentation ◽

Analytical Techniques ◽

Micropore Volume ◽

Operating Pressure ◽

Sunflower Seeds ◽

Plasma Expansion ◽

Maize Silage ◽

External Surface Area

A prototype capable of generating underwater high-voltage discharges (3.5 kV) coupled with water plasma expansion was constructed. The level of phytomass disintegration caused by transmission of the pressure shockwaves (50–60 MPa) followed by this expansion was analyzed using gas adsorption techniques. The dynamics of the external surface area and the micropore volume on multiple pretreatment stages of maize silage and sunflower seeds was approximated with robust analytical techniques. The multiple increases on the reaction surface were manifest in up to a 15% increase in cumulative methane production, which was itself manifest in the overall acceleration of the anaerobic fermentation process. Disintegration of the sunflower seeds allowed up to 45% higher oil yields using the same operating pressure.

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Photocatalytic Activity inCH3CN Related to the Surface Properties ofTiO2Powders Prepared by Sol-Gel Method

International Journal of Photoenergy ◽

10.1155/2009/905987 ◽

2009 ◽

Vol 2009 ◽

pp. 1-6 ◽

Cited By ~ 3

Author(s):

Marta Bettoni ◽

Pietro Candori ◽

Fabio Marmottini ◽

Nicoletta Perenze ◽

Cesare Rol ◽

...

Keyword(s):

Photocatalytic Activity ◽

Surface Area ◽

External Surface ◽

Sol Gel ◽

Micropore Volume ◽

Bet Surface Area ◽

External Surface Area ◽

Test Reaction ◽

Gel Method ◽

Sol Gel Method

SomeTiO2powders, prepared from titanium(IV)tetraisopropoxide by the sol-gel method and thermally treated between 100 and1000∘C, have been characterized by X-ray powder diffraction and by nitrogen adsorption and desorption at 77 K to calculate the BET-specific surface area, from which the micropore volume and the external surface area can be derived. The photocatalytic activity (ka) of the above powders has been evaluated considering theTiO2-sensitized photo-oxidation of 4-methoxybenzyl alcohol inCH3CN as the test reaction. The decrease ofkahave been related to the decrease of the BET surface area, the micropore volume, and the external surface area of theTiO2powders, but a satisfactory linear correlation is observed only for the last superficial parameter.

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Influence of alkyl chain length on the action of acetylated monoglycerides as plasticizers for poly (vinyl chloride) food packaging film

Food Packaging and Shelf Life ◽

10.1016/j.fpsl.2020.100619 ◽

2021 ◽

Vol 27 ◽

pp. 100619

Author(s):

Chang Woo Kwon ◽

Pahn-Shick Chang

Keyword(s):

Chain Length ◽

Vinyl Chloride ◽

Food Packaging ◽

Alkyl Chain ◽

Alkyl Chain Length ◽

Packaging Film ◽

Poly Vinyl Chloride

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Silver Nanoparticles Stabilized with Phosphorus-Containing Heterocyclic Surfactants: Synthesis, Physico-Chemical Properties, and Biological Activity Determination

Nanomaterials ◽

10.3390/nano11081883 ◽

2021 ◽

Vol 11 (8) ◽

pp. 1883

Author(s):

Martin Pisárčik ◽

Miloš Lukáč ◽

Josef Jampílek ◽

František Bilka ◽

Andrea Bilková ◽

...

Keyword(s):

Silver Nanoparticles ◽

Biological Activity ◽

Zeta Potential ◽

Chain Length ◽

Alkyl Chain ◽

Chemical Properties ◽

Alkyl Chain Length ◽

Microbial Pathogens ◽

Physico Chemical ◽

Phosphorus Containing

Phosphorus-containing heterocyclic cationic surfactants alkyldimethylphenylphospholium bromides with the alkyl chain length 14 to 18 carbon atoms were used for the stabilization of silver nanodispersions. Zeta potential of silver nanodispersions ranges from +35 to +70 mV, which indicates the formation of stable silver nanoparticles (AgNPs). Long-chain heptadecyl and octadecyl homologs of the surfactants series provided the most intensive stabilizing effect to AgNPs, resulting in high positive zeta potential values and smaller diameter of AgNPs in the range 50–60 nm. A comparison with non-heterocyclic alkyltrimethylphosphonium surfactants of the same alkyl chain length showed better stability and more positive zeta potential values for silver nanodispersions stabilized with heterocyclic phospholium surfactants. Investigations of biological activity of phospholium-capped AgNPs are represented by the studies of antimicrobial activity and cytotoxicity. While cytotoxicity results revealed an increased level of HepG2 cell growth inhibition as compared with the cytotoxicity level of silver-free surfactant solutions, no enhanced antimicrobial action of phospholium-capped AgNPs against microbial pathogens was observed. The comparison of cytotoxicity of AgNPs stabilized with various non-heterocyclic ammonium and phosphonium surfactants shows that AgNPs capped with heterocyclic alkyldimethylphenylphospholium and non-heterocyclic triphenyl-substituted phosphonium surfactants have the highest cytotoxicity among silver nanodispersions stabilized by the series of ammonium and phosphonium surfactants.

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