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A Physical and Chemical Equilibrium
Published in Danny D. Reible, Fundamentals of Environmental Engineering, 2017
The solubility of compounds that are solids or gases at the temperatures for which solubility is desired are much more sensitive to temperature. The enthalpy change upon dissolution includes both the heat of solution and the latent heat of the phase change. Because the latent heats associated with phase changes are large, the total heats of solution are large and a strong temperature dependence of solubility results. For gases, the enthalpy of the phase change is the heat of condensation, i.e., the negative of the heat of vaporization,ΔHv, and the temperature dependence is approximately given by (with α again a constant of integration) () lnS˜w≈α−−ΔH^vRT
Formulation Development of Small-Volume Parenteral Products
Published in Sandeep Nema, John D. Ludwig, Parenteral Medications, 2019
Madhav S. Kamat, Patrick P. DeLuca
A positive heat of solution indicates that the process is endothermic (i.e., the solute absorbs heat when dissolving). Therefore, an increase in temperature will increase solubility. A negative value indicates that the process is exothermic (i.e., the solute evolves heat when dissolving). In this case, increase in temperature results in a decrease in solubility. A differential heat of solution around zero indicates that the solubility is not significantly influenced by temperature.
Experimental Studies on Endothermic Reversible Reaction of Salts for Cooling
Published in Heat Transfer Engineering, 2021
Fenil Desai, Asonganyi Atayo, Jenne Sunku Prasad, Palanisamy Muthukumar, Muhammad Rahman, Eylem Asmatulu
The concept of endothermic cooling is very simple from the chemistry point of view and has a considerable potential to produce a cooling effect. A salt-based cooling system using the endothermic heat of reaction was defined by Rodeck [18] and Telkes [19] in 1955 and 1977, respectively; however, there has not been much research involving salts that could be applied to cooling applications. The COP of the endothermic cooling must be an integral part of the heat of solution (cal/moles) and to the heat of water vaporization (cal/moles of water). The ideal solution of salt-water mixtures that do not agglomerate is calculated by where T is the absolute temperature, P is constant pressure, is the heat of solution per mole of solute,
Treatment options for nanofiltration and reverse osmosis concentrates from municipal wastewater treatment: A review
Published in Critical Reviews in Environmental Science and Technology, 2019
Kimmo Arola, Bart Van der Bruggen, Mika Mänttäri, Mari Kallioinen
Several crystallization technologies such as evaporation crystallization, cooling crystallization, reactive crystallization and seed accelerated crystallization have been studied as potential technologies to enhance the water recovery rates or to recover salts or nutrients from municipal wastewater effluents such as membrane concentrates (Berg, Knoll, Kaschka, Weidler, & Nüesch, 2007; Berg et al., 2005, 2006; Fernández-Torres, Randall, Melamu, & von Blottnitz, 2012; Lahav et al., 2013; Lee, Weon, Lee, & Koopman, 2003; Lu et al., 2017; Sanciolo et al., 2012; Sanciolo, Zou, Gray, Leslie, & Stevens, 2008; Tran et al., 2012, 2014). In evaporation crystallization, a heat treatment is used to detach the solvent from the solute and solute starts to crystallize in the form of solid state crystals. Initially the solution is unsaturated at a given temperature and external heat source is used to gradually heat the solution and remove the solvent. Solvent gradually evaporates from the solution and saturation point is reached after which crystallization of the solute occurs. Multi-effect evaporation crystallization and mechanical vapor recompression crystallization are the two main types of evaporation crystallization (Lu et al., 2017). Cooling crystallization is typically utilized for solutions in which the solubility of solute have strong dependence of the temperature. Usually, solubility of many chemical compounds decreases by decreasing temperature of the solution. These compounds can be crystallized by cooling the solution under feasible conditions. Cooling crystallization can be divided into three different techniques: solute crystallization, freezing crystallization and eutectic freeze crystallization (Lu et al., 2017).