Equilibrium desorption isotherms of water, ethanol, ethyl acetate, and toluene on a sodium smectite clay

Clausen, Pascal; Signorelli, Marco; Schreiber, Andreas; Hughes, E. W.; Plummer, C. J. G.; Fessas, Dimitrios; Schiraldi, Alberto

doi:10.1007/s10973-009-0003-x

Cited by 14 publications

(9 citation statements)

References 35 publications

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“…The difference in the binding energies of the molecules considered here can be well explained in terms of their chemical nature. These results allow us also to interpret very recent experiments reported in ref 17 where volatiles were ranked on the basis of their observed desorption trends from the smectite clay considered here. In the low-coverage regime, the order of the ranking was ethyl acetate, ethanol, water, and toluene.…”

Section: Discussionsupporting

confidence: 76%

“…Ts.th.2.1532.1552.1712.1802.170Os.th.2.1262.0792.1432.1302.130Δ Z 0.2480.1610.2610.2100.310Ψ5658565757 d (Si−O b )1.6121.6151.6251.6201.6351.670 d (Si−O a )1.6331.6231.6441.6301.660 d (Al−O a )1.9221.9531.9321.9201.9501.940 d (Al−O h )1.8881.9381.8961.8901.9101.900 d (O h −H)0.9640.9700.977∠(O b −Si−O b )110110109109109.5110.1∠(Si−O b −Si)132132130130145141142144∠(O b −Si−O a ) (τ)109109109109108.6∠(Al−Si−O a )123122124126128126128∠(O a −Al−O a )9394929294.8∠(Al−O a −Al)102100102102∠(O h −Al−O a )94949494939492∠(Al−O h −Al)104100103103∠(Al−O h −H)121 a Symbols are as in Table A1. Note that the unit-cell parameters used in “this work” are those given in ref (see part A). …”

Section: A1mentioning

confidence: 99%

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Adsorption of Low-Molecular-Weight Molecules on a Dry Clay Surface: An Ab Initio Study

et al. 2009

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We present a study of the adsorption of single molecules of volatiles, such as water, ethanol, ethyl acetate, pyridine, toluene, and n-octane, on the dry surface of a smectite clay using a series of calculations based on density functional theory. Our clay model contains both tetrahedral and octahedral substitutions, and sodium as the counterion. After establishing the accuracy of our calculations for predicting the structural features of known clays, we determine the structural features of our model clay and then characterize the changes induced by molecular adsorption and the dependence of binding on the adsorption site. In all cases, binding energies are higher in configurations bound to cations located above rings with tetrahedral substitution than for those above rings with octahedral substitutions. For molecules containing an electronegative atom, binding energies inversely correlate well with their ionization potential. Our results allow an interpretation of the trend of measured vaporization rates at low coverage and reveal that they correlate inversely with the binding energies of the molecules.

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Section: Discussionsupporting

confidence: 76%

Section: A1mentioning

confidence: 99%

Adsorption of Low-Molecular-Weight Molecules on a Dry Clay Surface: An Ab Initio Study

et al. 2009

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“…The results are compared with previously obtained data of equilibrium desorption isotherms (Clausen et al, 2009b). The different volatiles (water, ethanol, ethyl acetate, and toluene) were adsorbed on (Na + -rich) montmorillonite at 0.95 activity (i.e.…”

Section: Isothermal Rate Of Desorption Of Volatiles From the (Na +Ricmentioning

confidence: 85%

Kinetics of Desorption of Water, Ethanol, Ethyl Acetate, and Toluene from a Montmorillonite

Clausen

Meier²,

Hughes

et al. 2013

Clays and clay miner.

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Desorption processes of low-molecular-weight compounds from the surface of smectites into the gas phase determine a number of processes, e.g. those involved in drug delivery and the release of herbicides. The desorption has not been investigated thoroughly and is not well understood. The present study was undertaken in order to understand better the factors influencing these desorption mechanisms. Starting with a very pure standard (Na + -rich) montmorillonite (Kunipia-F), which was exchanged against cations with different hydration properties (Ca 2+ , Li + , phenyltrimethylammonium, hexyltrimethylammonium), the experiments explored the rate of desorption of volatiles with different chemical functionalities (water, ethanol, ethyl acetate, and toluene). The desorption was monitored by thermogravimetry and differential scanning calorimetry under isothermal conditions, and by ramping the temperature at a constant rate. The experiments were compared with numerical calculations based on finite-element methods and with analytical models. These data point to a two-step mechanism where the desorption follows the curve of the equilibrium desorption isotherms of those molecules on the montmorillonite. The bulk-like volatiles (i.e. volatiles with release kinetics close to that of the bulk liquids) were desorbed in a first step. With a decrease in the degree of coverage of the volatile on the montmorillonite, the desorption was increasingly dominated by the strength of interaction between the volatile and the interlayer cations of the montmorillonite.

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“…Details of the method are reported elsewhere [ 39 ]. This method is continuous and each measurement produces the overall desorption isotherm with high reproducibility also in the low water activity ranges but can be applied only in the desorption mode [ 41 , 42 , 43 , 44 ]. A TG-DSC instrument (TG-DSC 111, SETARAM, Caluire, France) operating with a typical sample mass of 30 mg was used.…”

Section: Methodsmentioning

confidence: 99%

The Effect of Moisture on Cellulose Nanocrystals Intended as a High Gas Barrier Coating on Flexible Packaging Materials

et al. 2017

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Cellulose nanocrystals (CNCs) exhibit outstanding gas barrier properties, which supports their use as a biobased and biodegradable barrier coating on flexible food packaging materials. As highly hydrophilic biopolymers, however, CNCs have a strong sensitivity to water that can be detrimental to applications with fresh foods and in moist conditions due to the loss of barrier properties. In this work, the oxygen and water vapor permeability of polyethylene terephthalate (PET) films coated with CNCs obtained from cotton linters were measured at varying levels of relative humidity, both in adsorption and desorption, and from these data, the diffusion and solubility coefficients were estimated. Therefore, the characterization of CNCs was aimed at understanding the fundamentals of the water-CNCs interaction and proposing counteractions. The CNCs' moisture absorption and desorption isotherms at 25 • C were collected in the range of relative humidity 0-97% using different techniques and analyzed through GAB (Guggenheim-Anderson-de Boer) and Oswin models. The effects of moisture on the water status, following the freezable water index, and on the crystal structure of CNCs were investigated by Differential Scanning Calorimetry and by X-ray Powder Diffraction, respectively. These findings point to the opportunity of coupling CNCs with hydrophobic layers in order to boost their capabilities as barrier packaging materials.

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Equilibrium desorption isotherms of water, ethanol, ethyl acetate, and toluene on a sodium smectite clay

Cited by 14 publications

References 35 publications

Adsorption of Low-Molecular-Weight Molecules on a Dry Clay Surface: An Ab Initio Study

Adsorption of Low-Molecular-Weight Molecules on a Dry Clay Surface: An Ab Initio Study

Kinetics of Desorption of Water, Ethanol, Ethyl Acetate, and Toluene from a Montmorillonite

The Effect of Moisture on Cellulose Nanocrystals Intended as a High Gas Barrier Coating on Flexible Packaging Materials

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