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Water Treatment Calculations
Published in Frank R. Spellman, The Science of Water, 2020
Henry’s law is used to explain the dissolution of gaseous chlorine Cl2(aq). Henry’s law describes the effect of the pressure on the solubility of the gases: There is a linear relationship between the partial pressure of gas above a liquid and the mole fraction of the gas dissolved in the liquid (Fetter, 1998).
Mass Transfer
Published in C. Anandharamakrishnan, S. Padma Ishwarya, Essentials and Applications of Food Engineering, 2019
C. Anandharamakrishnan, S. Padma Ishwarya
Henry’s law provides a quantitative relationship between the pressure and solubility of a gas in a solvent, wherein, the solubility of a gas is defined as the concentration of the dissolved gas in equilibrium with the substance in the gaseous state. Under conditions of equilibrium, the rate at which the solute gas molecules escape the solution and enter the gas phase is equal to the rate at which gas molecules reenter the solution. Henry’s law states that at a constant temperature, the amount of a given gas that dissolves in a specific volume and type of a liquid is directly proportional to the partial pressure of that gas in equilibrium with that liquid. In simple terms, the amount of gas that can be solubilized in a liquid is directly dependent on the partial pressure exerted by that gas on the liquid at a constant temperature. Henry’s law is given by the expression cA=HpA
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Published in J. Russell Boulding, Epa Environmental Engineering Sourcebook, 2019
Hugh H. Russell, John E. Matthews, Guy W. Sewell
Henry’s Law Constant—Henry’s law states that the amount of gas that dissolves in a given quantity of liquid at constant temperature and pressure, is directly proportional to partial pressure of the gas above the solution. Henry’s coefficients, as a result, describe the relative tendency of a compound to volatilize from liquid to air. The Henry’s law constant for TCE is 0.00892 which is high enough, when combined with its low solubility in water and high vapor pressure, for efficient transfer of TCE to the atmosphere. The evaporation half-life of TCE in water is on the order of 20 minutes at room temperature in both static and stirred vessels (Dilling, 1975; Dilling et al., 1975).
Effects of gas absorption with chemical dissociation reaction on single slurry droplet drying
Published in Drying Technology, 2020
Yehonatan David Pour, Andrew Fominykh, Boris Krasovitov, Avi Levy
Gas absorption by an evaporating slurry droplet is affected by simultaneous heat and mass transfer processes, such as heat release during gas absorption, chemical dissociation reactions, diffusion of dissolved gas and ions in the liquid phase, and the effects of chemical dissociation reactions on the effective Henry’s law constant. Thus, the temporal evolutions of slurry droplet temperature and of concentration of the dissolved species are associated with different phenomena which lead to simultaneous heating and cooling of the droplet and a decrease and increase in the Henry’s law constant (Figures 4–6). In particular, heat release during gas absorption increases the surface temperature of the slurry droplet. On one hand, an increase in temperature leads to a decrease in the magnitude of the Henry’s law constant and decreases the flux of soluble gas into the droplet. On the other hand, this increases the mass flux of vapor from the surface of the droplet, which contributes to a decrease in temperature and an increase in the Henry’s law constant. The dissociation reaction also contributes significantly to the increase in the effective Henry’s law constant. The combined influences of these phenomena determine the maximum temperature reached at the surface of the slurry droplet.
Influence of water-film-forming-unit on the enhanced removal of carbon dioxide from mixed gas using water absorption apparatus
Published in Environmental Technology, 2020
Diem-Mai Kim Nguyen, Tsuyoshi Imai, Shahira Said Aly, Takaya Higuchi, Ariyo Kanno, Koichi Yamamoto, Masahiko Sekine
Normally, gas pressure plays an important role when using physical water absorption to remove CO2 from mixed gas. In order to evaluate and compare the influence of gas pressure on the CO2 removal process in both our novel absorption tank (equipped with 1 or 2 WFFUs) and a tank with non-WFFU, the removal capacity was measured (Figure 4). In the apparatus without equipping WFFU, the removal efficiency increases with pressure at an initial gas composition of 25% CO2 and 75% N2, a total gas flow rate of 15 L min−1, and a temperature of 15°C. When pressure rises from 0.25 to 0.70 MPa, the removal efficiency increases from 72.4% to 79.03%. These results show that, if a WFFU is not installed inside the chamber, pressure reveals a direct effect on the absorption process, as dictated by Henry’s law. Henry’s law states that the solubility of gas in the aqueous phase is directly proportional to the gas pressure. Thus, an increase in gas pressure improves CO2 dissolution in water and CO2 removal efficiency.
Potential use of thermophilic bacteria for second-generation bioethanol production using lignocellulosic feedstocks: a review
Published in Biofuels, 2023
Henry’s law states that the solubility of gases in liquid reduces with an increase in temperature. Thus, in thermophilic ethanologenesis, an almost anaerobic condition is achieved, further reducing contamination risks by aerobic microorganisms. Contamination due to various microbes significantly reduces the bioethanol productivity of a mesophilic reactor. Lactic acid bacteria are the primary contaminant in ethanol production in mesophilic reactor systems, which can be avoided in thermophilic ethanologenesis since most lactic acid bacteria grow best at 20–40 °C. Higher temperature also aids in higher reaction rates and thus faster feedstock conversion rates [17,51]. Thermophilic ethanologenesis is an exothermic process that releases heat during growth and fermentation. This heat can be used to maintain reactor temperature in fully insulated systems and help reduce approximately one-fourth of the energy required for distillation [45]. It has also been suggested that the high-temperature requirement for thermophilic bioethanol production will favour the downstream product recovery by continuous ethanol removal since ethanol easily vaporises at a temperature above 50 °C, thus reducing production costs. Various hybrid processes that combine membrane separation and distillation can further add an advantage in the industrial scenario, reducing energy requirements and production costs [52]. A study proposed a new technology termed membrane-assisted vapour stripping (MAVS), capable enough to separate 80% bioethanol from 5% ethanol-water fermentation feed with significant cost reduction [53]. In another study [54] demonstrated using the same technology to efficiently separate ethanol from as low as 1% ethanol solution with minimal energy requirement.