Adsorption of water on carbon materials: the formation of “water bridge” and its effect on water adsorption

2021 ◽  
pp. 127719
Author(s):  
Chengyong Wang ◽  
Yaowen Xing ◽  
Yizhu Lei ◽  
Yangchao Xia ◽  
Chenhu Zhang ◽  
...  
Keyword(s):  
Water Adsorption ◽  
Carbon Materials ◽  
Water Bridge ◽  
Adsorption Of Water

Analysis of Water Adsorption on Chitosan and Its Blends with Hydroxypropylcellulose

e-Polymers ◽  
2007 ◽  
Vol 7 (1) ◽  
Author(s):  
Maria Mucha ◽  
Kazimierz Wańkowicz ◽  
Jacek Balcerzak
Keyword(s):  
Hydrogen Bonds ◽  
Thermodynamic Parameter ◽  
Solid Surface ◽  
Mass Fraction ◽  
Water Adsorption ◽  
Vapour Phase ◽  
Heat Of Adsorption ◽  
Water Molecules ◽  
Monomolecular Layer ◽  
Adsorption Of Water

AbstractChitosan (CH) and hydroxypropylcellulose (HPC) adsorb water easily by hydrogen bonds formed with hydroxyl and amide groups present in their structures. Heat of adsorption is a thermodynamic parameter which is used to estimate the type of adsorbate molecule bond on a solid surface, among the others. Adsorption of water from vapour phase on chitosan, hydroxypropylcellulose and blends of both biopolymers in the form of films were carried out. Isotherms of water adsorption in the samples were described by the GAB equation. Correlations between mass fraction of chitosan in the sample (wf) and the values of GAB coefficients were obtained. From parameter c in the GAB equation mean heat of adsorption of the first monomolecular layer of water molecules E1, and pure molar heat of adsorption q were determined.

S/O-Functionalities on Modified Carbon Materials Governing Adsorption of Water Vapor

2013 ◽  
Vol 117 (44) ◽  
pp. 23057-23065 ◽  
Author(s):  
Jing Xiao ◽  
Zhenlong Liu ◽  
Kyungsoo Kim ◽  
Yongsheng Chen ◽  
Jian Yan ◽  
...  
Keyword(s):  
Water Vapor ◽  
Carbon Materials ◽  
Adsorption Of Water ◽  
Adsorption Of Water Vapor

Adsorption of water molecules on the surface of photo-catalyst: a first principles theoretical comparison between InVO4 and rutile TiO2

2002 ◽  
Vol 751 ◽  
Author(s):  
M. Oshikiri ◽  
M. Boero ◽  
J. Ye
Keyword(s):  
First Principles ◽  
Water Adsorption ◽  
Adsorption Process ◽  
Catalyst Surface ◽  
Chemical Reactivity ◽  
Water Molecules ◽  
Activation Energy Barrier ◽  
Reaction Proceeds ◽  
Adsorption Of Water ◽  
Dynamics Simulations

ABSTRACTThe adsorption process of water molecules on the surface of InVO4 has been investigated via first principles molecular dynamics simulations and compared with that of the well-known rutile TiO2. We have found that the surface of InVO4 shows a remarked chemical reactivity whenever comes in contact with water and H2O molecules are often adsorbed dissociatively on its surface. The reaction proceeds spontaneously in a way similar to the case of TiO2 and does not require the overcoming of an activation energy barrier. The peculiar atomic connectivity of the InVO4 bulk crystal structure and the changes at the catalyst surface induced by the water adsorption are discussed and compared with the TiO2 system.

scholarly journals Water Adsorption Properties of Free and Dehydrated β-Cyclodextrin Studied by near Infrared Spectroscopy and Gravimetry

2016 ◽  
Vol 689 ◽  
pp. 143-147 ◽  
Author(s):  
Alfred A. Christy
Keyword(s):  
Hydrogen Bonds ◽  
Infrared Spectra ◽  
Water Adsorption ◽  
Near Infrared ◽  
Adsorption Properties ◽  
Water Molecules ◽  
Hydroxyl Groups ◽  
Oh Groups ◽  
Near Infrared Spectra ◽  
Adsorption Of Water

β-cyclodextrin, like other carbohydrates has a tendency to adsorb water molecules and the properties are attributed to the hydroxyl groups in the molecules. β-cyclodextrin, the cyclic oligomer of glucose has a hydrophobic interior and hydrophilic exterior. The cyclic structure favours the formation of hydrogen bonds between the OH groups on the adjacent glucose units and affects the formation of hydrogen bonds with water molecules. The hydoxyl groups engaged in hydrogen bondings can be eliminated at high temperatures and the adsorption properties of the dehydrated β-cyclodextrin will depend on the new functional groups formed. The aim of the report is to discuss the issue of the water adsorption properties of free and dehydrated β-cyclodextrin. Dry β-cyclodextrin and dehydrated β-cyclodextrin at temperatures 250, 300 and 350 °C were allowed to adsorb water from a humidity controlled air environmennt and the evolving near infrared spectra were measured using a near infrared spectrometer equipped with a transflectance accessory. The near infrared spectra in the region 10,000-4000 cm-1 and their second and fourth derivative profiles were used in studying the variation in the adsorption characteristics of dehydrated β-cyclodextrin. The results of the analyses show that the adsorption of water by β-cyclodextrin decreses at 300 °C compared to 200 and 250 °C. Dehydration forms more of the ethereal type-O-bonds in the molecule and explains the decrease in the water molecular adsorption at higher dehydration temperatures.

Comparison of Water Adsorption Properties of Cellulose and Cellulose Nanocrystals Studied by Near-Infrared Spectroscopy and Gravimetry

2017 ◽  
Vol 735 ◽  
pp. 235-239 ◽  
Author(s):  
Thamonwan Angkuratipakorn ◽  
Jirada Singkhonrat ◽  
Alfred A. Christy
Keyword(s):  
Infrared Spectroscopy ◽  
Near Infrared Spectroscopy ◽  
Cellulose Nanocrystals ◽  
Water Adsorption ◽  
Near Infrared ◽  
Adsorption Properties ◽  
Water Molecules ◽  
Oh Groups ◽  
Adsorption Processes ◽  
Adsorption Of Water

The adsorption properties of water molecules on cellulose and cellulose nanocrystals (CNCs), isolated from defatted rice bran (DRB) by 55% sulfuric acid hydrolysis under sonication were investigated. The powdered samples of cellulose and CNCs were analysed by using near infrared spectroscopy (NIR) and gravimetry at 38% and 55% humidities. Small amounts of samples were dried under vacuum at 120°C and the NIR spectra of the dry samples and their spectra during the adsorption water molecules were measured by using an NIR spectrometer equipped with a transflectance accessory and a DTGS detector. The quantitative adsorption of water molecules by the samples was determined by gravimetry. Second and fourth derivative profiles of the NIR spectra were used in understanding the chemistry of adsorption of water molecules and the adsorption processes by the samples. The results show that the adsorption of water molecules by the cellulose samples gives rise to three prominent peaks that can be related to the water molecules engaged in hydrogen bonding with C2, C3 and C6-OH groups on the glucose units of the cellulose polymers. Furthermore, the cellulose nanocrystals adsorb twice as much of water as the cellulose polymer. It is also clear from the results that C2 and C3-OH groups in the glucose units adsorb water molecules at a faster rate than the C6-OH group and responsible for nearly 50% of the water adsorption.

AN INVESTIGATION INTO THE OBSERVATION OF WATER ADSORPTION INTO BARBITONE POWDER

1991 ◽  
Vol 05 (28) ◽  
pp. 1859-1864
Author(s):  
M. ASHRAF CHAUDHRY
Keyword(s):  
Dielectric Response ◽  
Water Adsorption ◽  
Adsorbed Water ◽  
Small Component ◽  
Adsorption Of Water

The adsorption of water in a sample of barbitone has been studied by the dielectric technique over a frequency span between 10 Hz and 100 kHz. It has been found that the adsorbed water only contributes a small component to the dielectric response although the indications are that a large amount of water has been adsorbed. This means that the adsorbed water is in a bound form.

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

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.

Adsorption of water induces a reversible structural phase transition and colour change in new nickel(ii) macrocyclic complexes forming flexible supramolecular networks

2016 ◽  
Vol 40 (9) ◽  
pp. 7465-7475 ◽  
Author(s):  
Brenda Lizette Ruiz-Herrera ◽  
Marcos Flores-Álamo ◽  
Rubén Alfredo Toscano ◽  
Roberto Escudero ◽  
Martha Elena Sosa-Torres
Keyword(s):  
Phase Transition ◽  
Structural Phase Transition ◽  
Ligand Exchange ◽  
Water Adsorption ◽  
Structural Phase ◽  
Colour Change ◽  
Macrocyclic Complexes ◽  
Reversible Reaction ◽  
Adsorption Of Water ◽  
Supramolecular Networks

A reversible reaction of ligand-exchange in a nickel(ii)–tpmc complex, promoted by water adsorption, results in a structural phase transition accompanied by colour change.

scholarly journals Adsorption and dielectric properties of natural composite polymer wood

2020 ◽  
pp. 30-32
Author(s):  
V. V. Saushkin ◽  
N. N. Matveev ◽  
N. YU. Evsikova ◽  
N. S. Kamalova
Keyword(s):  
Water Adsorption ◽  
Adsorption System ◽  
Natural Polymer ◽  
Composite Polymer ◽  
Dielectric Parameters ◽  
Initial Stage ◽  
State Of Water ◽  
Adsorption Of Water ◽  
Migration Polarization ◽  
Natural Composite

The state of water in a natural polymer, wood, was studied by its eff ect on the dielectric parameters and currents of thermostimulated depolarization (TSD) of the adsorption system. It has been shown that surface wood hydroxyls do not play a signifi cant role in the adsorption of water, which occurs mainly in pores of varying volume. Interpretation of the behavior of the TSD currents showed that at the initial stage the polarization linearly depends on the water adsorption value, then this linearity is violated, which we associate with the onset of migration polarization.

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