Effect of Water Adsorption on Cation-Surface Interaction Energy in the Na-Mordenite of 5.5 : 1 Si/Al Ratio

The mobility of the Na+cations localized at the inner surface of the studied mordenite zeolite depends on the material surface properties. In this work, we show that the activation energy,ΔEhop, relating to the Na+cation hopping displacement is associated to the surface potential and therefore can be used to get a better insight into the zeolite surface properties. Indeed, when molecules as water are adsorbed at the surface, they modify the surface potential energy and hence influence the value ofΔEhop. If the adsorbed molecules are polar they directly interact with the cations which become more mobile. The more theΔEhopvalue is, the less the amount of adsorbed water molecules is. Alterations of theΔEhopvalue with respect to the amount of adsorbed water molecules are interpreted using the Dubinin model which is based on simple adsorption principle.

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The relationship between inner surface potential and electrokinetic potential from an experimental and theoretical point of view

Environmental Chemistry ◽

10.1071/en16216 ◽

2017 ◽

Vol 14 (5) ◽

pp. 295 ◽

Cited By ~ 7

Author(s):

Tajana Preočanin ◽

Danijel Namjesnik ◽

Matthew A. Brown ◽

Johannes Lützenkirchen

Keyword(s):

Surface Properties ◽

Surface Potential ◽

Single Particle ◽

Surface Reactions ◽

Solid Particles ◽

Theoretical Point ◽

Surface Characterisation ◽

Layer Potential ◽

Average Surface ◽

Inner Surface

Environmental contextInterfacial properties of colloid and nanoparticles are directly related to the reactivity and surface densities of existing surface sites. Surface characterisation of particles provides only some kind of average surface properties. Analysis of well-defined monocrystal surfaces, which form the surface of the single particle, leads to a better understanding of surface reactions and mutual interactions of adjacent crystal planes on average surface properties. AbstractThe contact of small solid particles and macroscopic flat planes with aqueous electrolyte solutions results in the accumulation of ions at the interface and the formation of the electrical interfacial layer. Analysis of well-defined monocrystal surfaces, which are the building blocks of a single particle, leads to a better understanding of surface reactions and mutual interactions of adjacent crystal planes on average surface properties of particles. We analyse inner surface potential (obtained by single-crystal electrode) and zeta-potential data (obtained by streaming potential measurements) that were obtained on identical samples. Among the systems for which comparable surface and zetapotentials are available, measured inner surface potential data for sapphire (0001), haematite (0001) and rutile (110) show the expected behaviour based on the face-specific surface chemistry model, whereas the slopes for rutile (110) and quartz (0001) do not. Isoelectric points for sapphire (0001), haematite (0001) and rutile (100) are in conflict with the standard model that implies consistent behaviour of surface potential and diffuse layer potential. For the two former systems, previous results from the literature suggest that the charge of interfacial water can explain the discrepancy. The water layer could also play a role for quartz (0001), but in this case, the discrepancy would simply not be noticed, because both point of zero potential and isoelectric point are low. Along with data on silver halides, it can be concluded that six-ring water structures on solids may generate the electrokinetic behaviour that is typical of inert surfaces like Teflon.

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Calorimetric and Spectroscopic Studies of Water Adsorption onto Alkaline Earth Fluorides

Adsorption Science & Technology ◽

10.1260/026361705774859910 ◽

2005 ◽

Vol 23 (6) ◽

pp. 425-436

Author(s):

Toshinori Mori ◽

Yasushige Kuroda ◽

Ryotaro Kumashiro ◽

Koji Hirata ◽

Hidehiro Toyota ◽

...

Keyword(s):

Alkaline Earth ◽

Water Adsorption ◽

Adsorbed Water ◽

Spectroscopic Studies ◽

Water Molecules ◽

Earth Fluoride ◽

Alkaline Earth Fluoride ◽

Pretreatment Temperature ◽

Argon Adsorption ◽

Ir Bands

Interactions between the surfaces of alkaline earth fluorides (CaF2, SrF2 and BaF2) and water molecules were investigated by calorimetric and spectroscopic methods. The exposed surfaces of the alkaline earth fluoride samples, with which the (100) crystalline plane is mainly associated, were found to be fully covered with strongly adsorbed water molecules, resulting in characteristic IR bands at 3684, 2561, 1947 and 1000 cm−1, respectively. This surface was homogeneous towards further water adsorption. The strongly adsorbed water molecules were almost completely desorbed from the surface on evacuating the sample up to 473 K. The heat of immersion in water also increased with increasing pretreatment temperature; this may be attributed to surface rehydration of the alkaline earth fluorides. The state of the surface changed drastically as the pretreatment temperature was increased and stabilized towards incoming water molecules. Thus, the surface formed after evacuation at temperatures greater than 473 K was resistant to hydration even after immersion in water at room temperature. This surface was relatively heterogeneous towards water adsorption, although it behaved homogeneously towards argon adsorption. These facts indicate that strongly adsorbed water molecules appear to be somewhat specific towards the adsorption of further incoming water molecules. The adsorption properties of the (100) plane of alkaline earth fluorides towards water and argon molecules depend strongly on both the electrostatic field strength and the extent of rehydration of the alkaline earth fluoride surface.

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Water adsorption and desorption pretreatment of surfaces increases the maximum amount of adsorbed water molecules by a multiple

Adsorption ◽

10.1007/s10450-013-9536-1 ◽

2013 ◽

Vol 19 (6) ◽

pp. 1127-1135 ◽

Cited By ~ 3

Author(s):

Dietmar Neuhaus

Keyword(s):

Water Adsorption ◽

Adsorbed Water ◽

Maximum Amount ◽

Water Molecules ◽

Adsorption And Desorption

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Quick Removal of Adsorbed Water Molecules on inner Surface of Metal Organic Chemical Vapor Deposition Equipment.

Shinku ◽

10.3131/jvsj.44.298 ◽

2001 ◽

Vol 44 (3) ◽

pp. 298-301

Author(s):

Katsumasa SUZUKI ◽

Takayuki SATOU ◽

Yoshio ISHIHARA ◽

Hiroki TOKUNAGA

Keyword(s):

Chemical Vapor Deposition ◽

Vapor Deposition ◽

Chemical Vapor ◽

Adsorbed Water ◽

Organic Chemical ◽

Water Molecules ◽

Inner Surface ◽

Metal Organic ◽

Organic Chemical Vapor Deposition

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Synthesis, structure and water sorption in Zr metal-organic frameworks

Acta Crystallographica Section A Foundations and Advances ◽

10.1107/s2053273314087592 ◽

2014 ◽

Vol 70 (a1) ◽

pp. C1240-C1240

Author(s):

Felipe Gándara ◽

Hiroyasu Furukawa ◽

Zhang Yue-Biao ◽

Juncong Jiang ◽

Wendy Queen ◽

...

Keyword(s):

Water Adsorption ◽

Metal Organic Frameworks ◽

Adsorbed Water ◽

Neutron Diffraction Study ◽

Water Molecules ◽

Remote Areas ◽

Adsorption Sites ◽

Thermal Batteries ◽

Secondary Building Units ◽

Metal Organic

Metal-organic frameworks (MOFs) based on zirconium secondary building units (SBUs) have proven to have great thermal and chemical stability,[1,2] which make them ideal for their use in different applications. We have prepared a series of six new MOFs made from the Zr6O4(OH)4(-CO2)nsecondary building units (n = 6, 8, 10, or 12) and variously shaped carboxyl organic linkers to make extended porous frameworks, with the aim of studying their performance as water adsorbents. Thus, we have evaluated the water adsorption properties of these new MOFs and other reported porous materials to identify the compounds with the most promising materials for use in applications such as thermal batteries or delivery of drinking water in remote areas. An X-ray single-crystal and a powder neutron diffraction study reveal the position of the water adsorption sites in one of the best performing materials, and highlight the importance of the intermolecular interactions between adsorbed water molecules within the pores.

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Water Structure in Proteins in Solid State Studied by Near Infrared Spectroscopy

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.735.168 ◽

2017 ◽

Vol 735 ◽

pp. 168-172

Author(s):

Siraporn Soonthonhut ◽

Alfred A. Christy

Keyword(s):

Infrared Spectroscopy ◽

Near Infrared Spectroscopy ◽

Water Adsorption ◽

Near Infrared ◽

Free Water ◽

Adsorbed Water ◽

Water Molecules ◽

Combination Frequency ◽

Adsorption Of Water ◽

Combination Frequencies

Water adsorption in proteins is the crucial process of protein folding and structure stabilizing. Adsorption of water on proteins can be evaluated by near-infrared spectroscopy, a useful technique for observing combination frequency of a water molecule. In this work, albumin, lysozyme, and silk, were used as models for α-helix and β-pleated sheet proteins. Their NIR spectra during water adsorption process were measured by using an NIR spectrometer equipped with a transflectance accessory. Moreover, the quantitative adsorption of water was determined by gravimetric technique. The results indicate that, there are five different NIR absorptions arise from the OH combination frequencies of water adsorbed by albumin in the 5300-5100 cm-1 region. But there are only four absorptions for lysozyme and silk. The OH combination frequencies arising from water molecules in albumin indicate that it acquires free water molecules (5280 cm-1) and adsorbed water molecules through carbonyl-water interactions (5248 and 5160 cm-1) and amino-water interactions (5200 and 5120 cm-1). Interestingly, there is no indication for the presence of free water molecules in lysozyme and silk. Furthermore, the gravimetric results indicate that the rate of water adsorbed follows the order RW.Alb<RW.Lys<RW.Sil and total mass of water adsorbed per gram solid follows the order WAlb<WLys=WSil.

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Ionic Properties of Vanadium Pentoxide Gels

MRS Proceedings ◽

10.1557/proc-121-167 ◽

1988 ◽

Vol 121 ◽

Cited By ~ 8

Author(s):

J. Livage ◽

P. Barboux ◽

J. C. Badot ◽

N. Baffier

Keyword(s):

Vanadium Pentoxide ◽

Water Adsorption ◽

Mixed Valence ◽

Adsorbed Water ◽

Water Molecules ◽

Proton Diffusion ◽

Hydrous Oxides ◽

Solution Interface ◽

Ionic Devices ◽

Acid Aqueous Medium

ABSTRACTVanadium pentoxide gels V2O5·nH2O are actually hydrous oxides. Water adsorption and dissociation occurs at the surface of the oxide leading to negatively charged oxide particles surrounded by an acid aqueous medium. Ionic conductivity is observed, arising from proton diffusion through the water molecules. This process mainly depends on the nature of adsorbed water molecules. Proton conductivity is strongly related to the water adsorption isotherm.Ion exchange readily occurs at the oxide-solution interface when the gel is dipped into an aqueous solution of a metal chloride. New vanadium bronzes have been obtained upon heating such gels around 300° C. They exhibit interesting properties as reversible cathodes.Electrochemical insertion of Li* into the gel phase is quite easy. This is due to the very open structure of the gel and the mixed valence behavior of the vanadium oxide.Transition metal oxide gels could then be used as thin films or pressed pellets for making micro-ionic devices.

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