When Water becomes an Integral Part of Carbon - Combining Theory and Experiment to Understand the Zeolite-like Water Adsorption Properties of porous C2N Materials

2021 ◽  
Author(s):  
Julian Heske ◽  
Ralf Walczak ◽  
Jan Dirk Epping ◽  
Sol Youk ◽  
Sudhir Kumar Sahoo ◽  
...  
Keyword(s):  
Water Adsorption ◽  
Adsorption Properties ◽  
Water Molecules ◽  
Theory And Experiment

The interaction between water molecules and surfaces in porous systems is of huge importance in various fields including but not limited to catalysis, adsorption, and the storage or conversion of...

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.

Hexavalent chromium removal from water: adsorption properties of in natura and magnetic nanomodified sugarcane bagasse

2021 ◽  
Author(s):  
Thais Eduarda Abilio ◽  
Beatriz Caliman Soares ◽  
Julia Cristina José ◽  
Priscila Aparecida Milani ◽  
Geórgia Labuto ◽  
...  
Keyword(s):  
Hexavalent Chromium ◽  
Sugarcane Bagasse ◽  
Water Adsorption ◽  
Adsorption Properties ◽  
Chromium Removal

Evaluation of solid state of rice flours produced by different milling processes using ATR-FTIR spectroscopy

2021 ◽  
Author(s):  
Daitaro Ishikawa ◽  
Jiamin Yang ◽  
Chiaki Ichikawa ◽  
Tomoyuki Fujii
Keyword(s):  
Solid State ◽  
Ir Spectra ◽  
Ftir Spectroscopy ◽  
Water Activity ◽  
Rice Flour ◽  
Milling Process ◽  
Adsorption Properties ◽  
Water Molecules ◽  
Rice Flours ◽  
Changes Of State

ABSTRACT This study evaluated the influence of the milling process on solid state of rice flours according to water activity using ATR-FTIR. A band at 1740 cm−1 attributed to the C=O stretching of lipids was detected for crystalline samples, and it disappeared at a high aw range. The CH band at 2930 cm−1 of crystalline samples gradually shifted to a higher wavenumber with aw. This band of the α-formed and wet-milled samples shifted to higher wavenumbers above 0.8aw. A band due to OH stretching mode in the 3500-3000 cm−1 region did not shift with aw. The result obtained from IR spectra suggests that the parameter K calculated by Guggenheim–Anderson–de Boar model reflected not only the interaction between water molecules but also the changes of state in solids. Consequently, the results from this study provide insights about the adsorption properties of nonideal solids such as rice flour.

scholarly journals Oxidized BPL Carbons

1993 ◽  
Vol 10 (1-4) ◽  
pp. 75-84 ◽  
Author(s):  
S.S. Barton ◽  
M.J.B. Evans ◽  
J.A.F. Macdonald
Keyword(s):  
Nitric Acid ◽  
Surface Area ◽  
Water Adsorption ◽  
Adsorption Properties ◽  
Bet Surface Area ◽  
Adsorption Sites ◽  
A Value ◽  
Nitrogen Desorption ◽  
Oxidized Carbon ◽  
Increasing Temperature

A series of oxidized carbons has been prepared by treatment of the carbon with concentrated nitric acid at various temperatures, and the surface and adsorption properties of the prepared carbons studied. Water adsorption was modelled using a recently derived equation capable of predicting a value for the primary adsorption sites on the surface of a microporous carbon while fitting the experimentally determined isotherm at high relative pressures. The concentration of primary sites was seen to increase with increasing temperature of oxidation. The very highly oxidized carbon samples were found to have a significantly lower BET surface area determined from nitrogen desorption at 77 K and higher apparent density measured from mercury displacement.

Surface area, porosity and water adsorption properties of fine volcanic ash particles

2004 ◽  
Vol 67 (2) ◽  
pp. 160-169 ◽  
Author(s):  
Pierre Delmelle ◽  
Fr�d�ric Villi�ras ◽  
Manuel Pelletier
Keyword(s):  
Surface Area ◽  
Volcanic Ash ◽  
Water Adsorption ◽  
Adsorption Properties

scholarly journals Calorimetric and Spectroscopic Studies of Water Adsorption onto Alkaline Earth Fluorides

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.

scholarly journals Water Adsorption to Leaves of Tall Cryptomeria japonica Tree Analyzed by Infrared Spectroscopy under Relative Humidity Control

Plants ◽  
2020 ◽  
Vol 9 (9) ◽  
pp. 1107
Author(s):  
Wakana A. Azuma ◽  
Satoru Nakashima ◽  
Eri Yamakita ◽  
Tamihisa Ohta
Keyword(s):  
Hydrogen Bonding ◽  
Relative Humidity ◽  
Cryptomeria Japonica ◽  
Water Adsorption ◽  
Bound Water ◽  
Free Water ◽  
High Water ◽  
Water Molecules ◽  
Cross Sectional ◽  
Tissue Properties

Leaf water storage is a complex interaction between live tissue properties (anatomy and physiology) and physicochemical properties of biomolecules and water. How leaves adsorb water molecules based on interactions between biomolecules and water, including hydrogen bonding, challenges our understanding of hydraulic acclimation in tall trees where leaves are exposed to more water stress. Here, we used infrared (IR) microspectroscopy with changing relative humidity (RH) on leaves of tall Cryptomeria japonica trees. OH band areas correlating with water content were larger for treetop (52 m) than for lower-crown (19 m) leaves, regardless of relative humidity (RH). This high water adsorption in treetop leaves was not explained by polysaccharides such as Ca-bridged pectin, but could be attributed to the greater cross-sectional area of the transfusion tissue. In both treetop and lower-crown leaves, the band areas of long (free water: around 3550 cm−1) and short (bound water: around 3200 cm−1) hydrogen bonding OH components showed similar increases with increasing RH, while the band area of free water was larger at the treetop leaves regardless of RH. Free water molecules with longer H bonds were considered to be adsorbed loosely to hydrophobic CH surfaces of polysaccharides in the leaf-cross sections.

scholarly journals Adsorption Characteristics of Lead-, Barium- and Hydrogen-Rich Clinoptilolite Mineral

2003 ◽  
Vol 21 (4) ◽  
pp. 309-317 ◽  
Author(s):  
Fehime Cakicioglu-Ozkan ◽  
Semra Ulku
Keyword(s):  
Water Adsorption ◽  
Adsorption Properties ◽  
Adsorption Mechanisms ◽  
Adsorption Data ◽  
Vapour Adsorption ◽  
Water Vapour Adsorption ◽  
Rich Material ◽  
Static Conditions ◽  
Treatment Water

The carbon dioxide and water vapour adsorption properties of local clinoptilolite-rich material, both as the original and as lead-, barium- and hydrogen-rich forms, were examined. The lead- and barium-rich forms were prepared by treatment of the original clinoptilolite with Pb(NO3)2 and BaCl2 respectively, while the hydrogen-rich form was prepared by NH4Cl and heat treatment. Water and CO2 adsorption experiments were conducted in a volumetric system under static conditions, with low-pressure adsorption data being used for the characterization of the natural, Pb-rich, Ba-rich and H-rich clinoptilolite samples. Although the existence of barium-exchange was not noted, an appreciable decrease in CO2 adsorption was observed with the Pb-rich and H-rich forms due to a decrease in the electrostatic interaction between the surface and the adsorbate. Application of the Dubinin–Astakhov equation to the water adsorption data established the existence of micropores of different sizes that exhibited different adsorption mechanisms.

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.

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