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Properties of Ultrapure Water
Published in Tadahiro Ohmi, Ultraclean Technology Handbook, 2017
In general, boundary tension always exists where two phases contact each other. When one of the two phases is gas, the boundary tension is called surface tension. Surface tension is the amount of work required to push back against the tendency of a surface to shrink. The tendency to shrink is the cohesive force of the molecules comprising the liquid and has a close relationship with the interaction of molecules. Generally, surface tension tends to increase as the molecular weight increases. The surface tension of water is strong, although its molecular weight is low. This is because hydrogen bonds make water molecules appear larger than their actual size. Since such water clusters become smaller clusters or water molecules as the temperature rises or falls, the surface tension weakens and the evaporation of water is facilitated. As a result, the vapor pressure increases. The effect of temperature on the vapor pressure is much greater than that on surface tension. This is because even if the hydrogen bonds are cut because of the temperature rise, they are still able to help molecules to evaporate.
Selected Communications, Short Notes, and Abstracts
Published in V. B. Dement’ev, A. K. Haghi, V. I. Kodolov, Nanoscience and Nanoengineering, 2019
V. B. Dement’ev, A. K. Haghi, V. I. Kodolov
Activated water is the kind of water where hydrogen bonds are loosened, which makes molecules more mobile and, therefore, easier for living organisms to consume and also facilitates biological waste removal. The principle of water activation lies in destroying cluster structures to saturate the water with monomolecules. An activated water cluster contains 5–6 molecules (13–16 molecules in regular water), which makes it easier for cells of living organisms to consume such activated water and get rid of biological waste. Such water is considered more active as indicated by biological and biophysical parameters. Water activated via any method has a higher liquidity (due to lower surface tension) and a higher dissolving capacity. Water with smaller clusters have improved reactivity, better penetrates biological membranes, and is quicker extracted out of body. It efficiently substitutes and complements all kinds of cleansing supplements and physiotherapeutic procedures. Activated water is used for all-around detoxification, neutralization, and removal of waste, toxins carcinogens, and radionuclides. This chapter deals with the experimental data to determine the total antioxidant activity of aqueous systems, saturated with hydrogen using a coulometric analysis method, wherein water is observed on the highest increase of its activity up to 20 times. We analyzed the Arkhyz + antioxidant = Zhivitsa functional drink, where all the ingredients are of natural origin. Saturating the drink by hydrogen leads to an insignificant increase (16.5% rel.) of total antioxidant activity. The presence in the water of active organic compounds reduces the influence of hydrogen on the total antioxidant activity, probably consisting of different numbers of molecules.
Application of coarse-grained water model in the study of mixed collectors compounding mechanism in low-rank coal flotation
Published in International Journal of Coal Preparation and Utilization, 2023
Penghui Wang, Wenli Liu, Qiming Zhuo, Xiaopeng Sun
Table 1 displays the equilibrium configuration, hydrogen bond number, hydrogen bond length, system energy, and binding energy of each water cluster. As shown in the data, the structure of water clusters changes as the number of water molecules increases. Specifically, (H2O)n (n = 1 ~ 5) exhibits a two-dimensional planar structure, while (H2O)n (n = 6 ~ 18) forms a three-dimensional cylindrical structure consisting of three-membered rings, four-membered rings, five-membered rings, and so on. For instance, (H2O)10 adopts a two-layer cylindrical structure comprising of two five-membered rings, while (H2O)16 exhibits a four-layer cylindrical structure consisting of four four-membered rings. On the other hand, (H2O)n (n = 19 ~ 21) assumes a three-dimensional cage-like structure, and the formed water cluster structure includes not only the outermost layer of water molecules but also some internal water molecules.
Dynamical and interference effects in X-ray emission spectroscopy of H-bonded water – origin of the split lone-pair peaks
Published in Molecular Physics, 2023
Osamu Takahashi, Lars G. M. Pettersson
Two pentamer model structures are considered, i.e. a tetrahedrally coordinated water cluster as representative of the local coordination in the proposed low-density liquid (LDL) and a distorted water cluster, as proposed for the high-density liquid (HDL) [38]. The former is a double-donor/double-acceptor (D2A2) species with four surrounding water molecules positioned tetrahedrally with all O-O distances involving the central oxygen set to 2.8 Å, which corresponds to the first peak of the radial distribution function of liquid water [66]. The geometrical parameters related to hydrogen atoms of the surrounding oxygen atoms were taken from Ref. [67]. The disordered model cluster is a single-donor/single-acceptor (D1A1) with the O-O distance to the two H-bonded waters set to 2.95 Å, which is slightly longer than that for D2A2 to mimic the effect of a sixth water in the interstitial region (not explicitly included in the model). The O-O distance to the non-H-bonded waters was set to 3.6 Å to be well separated from the central water molecule giving a well-defined D1A1 species. The structure of the centre water molecule was optimised with the other four water molecules frozen.
Equilibrium and hysteresis formation of water vapor adsorption on microporous adsorbents: Effect of adsorbent properties and temperature
Published in Journal of the Air & Waste Management Association, 2022
Lijuan Jia, Ben Niu, Xiaoxia Jing, Yangfang Wu
To better understand the effect of temperature on water vapor adsorption, we evaluated the adsorption behavior on functional groups and pores under different temperatures. Fitting parameters presented in Table 1, especially S0 and Cus, showed apparent dependenceupon temperature. It is clear that the value of S0 and Cμs decreased with the increasing temperature, which reduced adsorptive contributions on both functional groups and micropores. From the results, a map of the change in water vapor adsorption on functional groups and micropores with increasing temperatures was created, presented in Figure 5, revealing a negative correlation with logarithm of temperature. This result was closely related to the adsorption mechanism of water vapor: adsorption through hydrogen-bond and water cluster formation followed by micropore filling. In addition, the lowering of S0 suggested water adsorbing on fewer functional groups. Thus, S0 does not mean the characterized concentration of functional groups but only the sites detected by water vapor. As for Cμs, because water molecules must obtain higher potential to stay in the micropore with the temperature rising and it became more difficult for water molecules to form clusters as the temperature increases (Wang, Tian, and Li 2019), the adsorption of water vapor in micropores decreased along with the increase of temperature.