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Published in Joseph C. Salamone, Polymeric Materials Encyclopedia, 2020
Hydration of various aliphatic (P4, P5, P8) or heterocyclic (P18, P19) polyammoniopropanesulfonates shows a common set of characteristic features.68,74,75 At 23 °C, water diffusion is Fickian whatever the physical state of the hydrated system—glassy or viscoelastic. Quantitative analysis of the sorption isotherms through the Guggenheim-Anderson-De Boer equation shows that water-vapor sorption occurs according to a multilayer sorption process characterized by a number of site-bound water molecules per monomeric unit, nml.3–2.0. Differential scanning calorimetry discriminates two types of bound water: nonfreezable but still fairly mobile bound water (n(I) ~ 5.0–8.5) and freezable bound water (melting temperature < 0 °C, n(II) ~ 5.5–7.5). In spite of similar dipole moment, the ammonioethoxydicyanoethenolate structure appears rather hydrophobic (nm = 0.68, n (I) = 2.8, n (II) = 0.4 for polymer P13) with respect to the very hydrophilic ammoniopropanesulfonate one.62,76
Properties and Characteristics of Water and Wastewater
Published in Donald R. Rowe, Isam Mohammed Abdel-Magid, Handbook of Wastewater Reclamation and Reuse, 2020
Donald R. Rowe, Isam Mohammed Abdel-Magid
There are various classes of water in sludges. For example Taylor14 classified the water in sludges as: Free water: water which will drain readily from the sludge, with or without the assistance of vacuum or pressure.Bound water: water which is a part of the particle structure by virtue of the charge upon the particle, and which is released by neutralization of that charge.Contained water: water which is an essential part of the structure of the particle and which requires drastic methods such as drying to effect removal.
Chloride Binding and Its Effects on Characteristics of Cement-Based Materials
Published in Shi Caijun, Yuan Qiang, He Fuqiang, Hu Xiang, Transport and Interactions of Chlorides in Cement-Based Materials, 2019
Shi Caijun, Yuan Qiang, He Fuqiang, Hu Xiang
Chemically bound water has been widely studied with the aid of measurement techniques, such as thermogravimetric analysis (TGA) (Pane and Hansen 2005) and Quasielastic neutron scattering (QNS) measurements (Berliner et al. 1998). Due to the non-mobility of chemically bound water, the influences of this type of water on performance of cement-based materials are generally insignificant. However, the free and adsorbed water plays an important role in the transportation of aggressive substances and interfacial properties of cement-based materials. Based on the Stern model about EDL formed at the solid–liquid interface, the adsorbed water in EDL has different properties than that in bulk pore solution. From the electrochemical point of view, the water molecules were considered being accumulated together with the charged ions within sub-nanometer distance from charged electrodes (Feng et al. 2014). The accumulation of water molecules is governed by the association of water molecules with their surrounding ions, which drives water molecules into position where the ions are highly charged. Bager et al. (1986a, b) studied the ice formation in hardened cement pastes with low-temperature Calvet microcalorimeter. They found that water contained in finer pores, physically adsorbed water in EDL formed on solid surface, or in a ‘‘interlayer’’ position was nonfrozen even under the condition of −55°C, and the freezable (free) water within saturated cement paste can be removed at a relative vapour pressure lower than 60% of atmospheric pressure.
Analysis of heat and moisture transfer in the microwave drying of potatoes
Published in Drying Technology, 2023
Lisen Bi, Bin Liu, Zhaodan Yang, Tonghua Zou, Songsong Zhao, Panagiotis E. Theodorakis
Figure 9c shows about 83% of the total water in fresh sample exists in the state of free water, the content of weakly bound water and immobilized water are close, with the bound water only accounting for 2.34% of the total water. During the microwave drying process, the content of free water increases from 82.73% to 93.21% and then decreases to 15.61%. The content of moisture with poor fluidity including the bound water (from 2.34% to 0.78%, then to 9.16%), the weakly bound water (from 8.05% to 1.47%, then to 23.74%) and the immobilized water (from 6.87% to 4.53%, then to 51.48%) all increase after an initial decrease. When the moisture content of sample is 20.5%, the moisture in the sample mainly exists in the form of immobilized water (51.48%), and most importantly the proportion of the weakly bound water also greatly increases (23.74%).
Assessment of the moisture storage characteristics of lignite focusing on lignite type, moisture forms and drying mechanism
Published in International Journal of Coal Preparation and Utilization, 2023
Lichao Ge, Han Jiang, Qian Li, Hongcui Feng, Xi Li, Chunyao Xu, Yuli Zhang, Chang Xu
(3) The water in lignite can be divided into free water and bound water according to whether there is any force between the water and coal. Bound water accounts for a relatively large proportion of the total water content. With an increasing temperature the proportion of bound water decreases, indicating that the increase of temperature provides more dehydration energy, and more bound water is converted into free water. The dehydration of bound water is affected by the lignite structure and can be further divided into chemical bound water, transitional bound water and physical bound water according to the different adsorption means of the molecular structure of water and coal. The drying rates of bound water conform to the exponential equation, linear equation, and logarithmic equation respectively. The first stage is the removal of physical adsorption water, the second stage is the removal of physical and chemical adsorption water, the third stage is the removal of chemical adsorption water. Accordingly, the total water content of lignite can be divided into four parts: chemical bound water, transitional bound water, physically bound water, and free water. The dehydration difficulty is successively reduced and the energy consumption is also successively reduced.
Fabric properties and electric efficiency limits of mechanical moisture extraction from fabrics
Published in Drying Technology, 2022
Ayyoub M. Momen, Viral K. Patel, Kyle R. Gluesenkamp, Donald Erdman, James Kiggans, Geoffrey Ormston
Water content in fabrics can also be divided into “free water” and “bound water”, which are terms used in the food[21] and textile[22] drying industries to describe how easily water can be extracted from these materials. In the context of fabrics, free water is the bulk liquid water that is found in inter- or intra-yarn pores and can easily be removed by squeezing or compressing the fabric by mechanical means. Bound water refers to the water trapped within the smaller pores such as intra-fiber pores through hydrogen bonding and is much more difficult to remove by mechanical forces. As such, a relatively large amount of energy is needed to remove bound water from fabric, and in cotton, for example, it can account for up to 8% of the fabric remaining moisture content even after the fabric has undergone a mechanical or evaporative drying process.[22]