Analysis and modeling of bound water adsorption by mixed clay based on adsorption theory

2021 ◽  
Vol 14 (12) ◽  
Author(s):  
Yanhua Xie ◽  
Zhaotian Zeng ◽  
Binghui Zhang ◽  
Yan Zhang ◽  
Shuanghui Tang
Keyword(s):  
Water Adsorption ◽  
Bound Water ◽  
Adsorption Theory

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.

Diffusion of tritiated water into water-saturated wood particles

Holzforschung ◽  
2006 ◽  
Vol 60 (1) ◽  
pp. 59-63 ◽  
Author(s):  
Aaron J. Jacobson ◽  
Sujit Banerjee
Keyword(s):  
Particle Size ◽  
Water Adsorption ◽  
Diffusion Rate ◽  
Tritiated Water ◽  
Bound Water ◽  
Fiber Structure ◽  
Wood Drying ◽  
Wood Particles ◽  
Free And Bound Water ◽  
Water Saturated

Abstract The diffusion rate of tritiated water into pine and aspen particles follows a Fickian mechanism. The tortuosity for the diffusion of water into wood is quite low, at approximately 1.6, and increases with decreasing particle size. The tortuosity for aspen is higher than that for pine because the shorter fiber structure in aspen gives rise to a more extensive network of pores. Diffusion into free and bound water occurs at the same rate. Also, diffusion into and out of the particles is nearly identical, demonstrating that diffusion of water into saturated wood particles is completely reversible. No hysteresis was evident, in contrast to behavior for water adsorption on unsaturated wood. The implications of these findings for pulping and wood drying are discussed.

scholarly journals Density Functional Theory Study of Bone Tissues: the Role of Water in Conferring Bone Strength

2020 ◽  
Vol 2 (2) ◽  
pp. 25
Keyword(s):  
Bone Strength ◽  
Density Functional ◽  
Water Adsorption ◽  
Experimental Studies ◽  
Bound Water ◽  
Adsorbed Water ◽  
Functional Theory ◽  
Explicit Solvent ◽  
Human Collagen

The unsurpassed mechanical properties of biomaterials stem from the intricate organization of inorganic and organic matter across length scales. In bone, water facilitates this organization, thereby playing an important structural role in addition to being a nutrient and waste transport medium. Water makes 10% of mammalian bone tissues and can be found in one of two states: bound (to the mineral phase) or mobile. While experimental studies were able to directly link the amount of bound water to bone strength, a molecular understanding of the interactions between the mineral (hydroxyapatite), organic (collagen) phase, and water is missing. In this talk, I will provide new insights into the water adsorption properties of bone tissues. I will present DFT calculations of water adsorption energy as a function of the environment, which includes an explicit solvent and human collagen fragments. I will show that the environment - rather than the mineral surface itself-governs the adsorption strength and mode. In particular, I will show that conditions consistent with aging tissues are associated with a lower density of adsorbed water molecules, which is a sign of weaker bones.

scholarly journals The effect of heat treatment on the moisture absorption characteristics of Cu-impregnated Masson’s pine wood

BioResources ◽  
2020 ◽  
Vol 15 (4) ◽  
pp. 8459-8471
Author(s):  
Lamei Li ◽  
Guijun Xie ◽  
Wanju Li ◽  
Yixin Li ◽  
Xingwei Li
Keyword(s):  
Heat Treatment ◽  
Surface Area ◽  
Water Adsorption ◽  
Moisture Absorption ◽  
Bound Water ◽  
Treated Wood ◽  
Free Water ◽  
Untreated Wood ◽  
Pine Wood ◽  
Heat Treated

The accumulation of water inside wood creates a favorable environment not only for molds, but also for wood-decaying fungi and insects. Therefore, the ability to limit water adsorption and retention is key to the longevity and performance of wood. In this study, the effect of heat-treatment and Cu nanoparticle (CuNP) impregnation on surface contact angle, specific surface area, and hygroscopicity of Masson’s pine wood was examined. Heat-treatment caused thermal degradation of hydroxyl-rich biopolymers, leading to an increase in hydrophobicity; while the resulting breakdown and blockage of the interior cell cavity network caused a decrease in effective surface area. In turn, the hygroscopicity of the heat-treated wood was considerably lower than the untreated wood. Analysis of water adsorption isotherms enabled the differentiation between bound water and free water, where the latter was a prerequisite for mold growth. The research showed that the amount of free water was reduced by both impregnation with CuNP and heat-treatment, but the previously observed antimicrobial activity was shown to rely on the presence of CuNPs as opposed to the reduced free water content. This study presented a detailed methodology for the preparation and analysis of heat-treated, CuNP-impregnated wood, and provided further insight into the mechanism of antimicrobial action of treated woods.

Mathematical Models of Papermaking

2001 ◽  
Vol 6 (1) ◽  
pp. 9-19 ◽  
Author(s):  
A. Buikis ◽  
J. Cepitis ◽  
H. Kalis ◽  
A. Reinfelds ◽  
A. Ancitis ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Initial Value Problems ◽  
Moisture Transfer ◽  
Bound Water ◽  
Drying Process ◽  
Initial Value ◽  
First Order ◽  
Heat And Moisture ◽  
The Mathematical Model ◽  
The Web

The mathematical model of wood drying based on detailed transport phenomena considering both heat and moisture transfer have been offered in article. The adjustment of this model to the drying process of papermaking is carried out for the range of moisture content corresponding to the period of drying in which vapour movement and bound water diffusion in the web are possible. By averaging as the desired models are obtained sequence of the initial value problems for systems of two nonlinear first order ordinary differential equations. 

Structure, Stability and Water Adsorption on Ultra-Thin TiO2 Supported on TiN

2019 ◽  
Author(s):  
Jose Julio Gutierrez Moreno ◽  
Marco Fronzi ◽  
Pierre Lovera ◽  
alan O'Riordan ◽  
Mike J Ford ◽  
...  
Keyword(s):  
Density Functional ◽  
Water Adsorption ◽  
Chemical Potential ◽  
Energy Gap ◽  
Molecular Water ◽  
Structure Stability ◽  
Ambient Conditions ◽  
Rutile Structure ◽  
The Stability ◽  
The One

<p></p><p>Interfacial metal-oxide systems with ultrathin oxide layers are of high interest for their use in catalysis. In this study, we present a density functional theory (DFT) investigation of the structure of ultrathin rutile layers (one and two TiO<sub>2</sub> layers) supported on TiN and the stability of water on these interfacial structures. The rutile layers are stabilized on the TiN surface through the formation of interfacial Ti–O bonds. Charge transfer from the TiN substrate leads to the formation of reduced Ti<sup>3+</sup> cations in TiO<sub>2.</sub> The structure of the one-layer oxide slab is strongly distorted at the interface, while the thicker TiO<sub>2</sub> layer preserves the rutile structure. The energy cost for the formation of a single O vacancy in the one-layer oxide slab is only 0.5 eV with respect to the ideal interface. For the two-layer oxide slab, the introduction of several vacancies in an already non-stoichiometric system becomes progressively more favourable, which indicates the stability of the highly non-stoichiometric interfaces. Isolated water molecules dissociate when adsorbed at the TiO<sub>2</sub> layers. At higher coverages the preference is for molecular water adsorption. Our ab initio thermodynamics calculations show the fully water covered stoichiometric models as the most stable structure at typical ambient conditions. Interfacial models with multiple vacancies are most stable at low (reducing) oxygen chemical potential values. A water monolayer adsorbs dissociatively on the highly distorted 2-layer TiO<sub>1.75</sub>-TiN interface, where the Ti<sup>3+</sup> states lying above the top of the valence band contribute to a significant reduction of the energy gap compared to the stoichiometric TiO<sub>2</sub>-TiN model. Our results provide a guide for the design of novel interfacial systems containing ultrathin TiO<sub>2</sub> with potential application as photocatalytic water splitting devices.</p><p></p>

scholarly journals Elucidating the Molecular Mechanisms for the Interaction of Water with Polyethylene Glycol-Based Hydrogels: Influence of Ionic Strength and Gel Network Structure

Polymers ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 845
Author(s):  
Xin Yang ◽  
Bronwin Dargaville ◽  
Dietmar Hutmacher
Keyword(s):  
Polyethylene Glycol ◽  
Ionic Strength ◽  
Molecular Mechanisms ◽  
Repeat Unit ◽  
Bound Water ◽  
Weight Fraction ◽  
Swelling Ratio ◽  
Polyethylene Glycol Diacrylate ◽  
Glycol Diacrylate ◽  
Hydrogel System

The interaction of water within synthetic and natural hydrogel systems is of fundamental importance in biomaterial science. A systematic study is presented on the swelling behavior and states of water for a polyethylene glycol-diacrylate (PEGDA)-based model neutral hydrogel system that goes beyond previous studies reported in the literature. Hydrogels with different network structures are crosslinked and swollen in different combinations of water and phosphate-buffered saline (PBS). Network variables, polyethylene glycol (PEG) molecular weight (MW), and weight fraction are positively correlated with swelling ratio, while “non-freezable bound water” content decreases with PEG MW. The presence of ions has the greatest influence on equilibrium water and “freezable” and “non-freezable” water, with all hydrogel formulations showing a decreased swelling ratio and increased bound water as ionic strength increases. Similarly, the number of “non-freezable bound water” molecules, calculated from DSC data, is greatest—up to six molecules per PEG repeat unit—for gels swollen in PBS. Fundamentally, the balance of osmotic pressure and non-covalent bonding is a major factor within the molecular structure of the hydrogel system. The proposed model explains the dynamic interaction of water within hydrogels in an osmotic environment. This study will point toward a better understanding of the molecular nature of the water interface in hydrogels.

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