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Carbon Membranes for Natural Gas Sweetening
Published in Xuezhong He, Izumi Kumakiri, Carbon Membrane Technology, 2020
Evangelos P. Favvas, Sotirios P. Kaldis, Xuezhong He
The first studies of separation membranes began in the eighteenth century (1748) when the Abbé Jean-Antoine Nollet, a French experimental physicist, proved that the bubbling phenomenon in decompressed liquids was caused by dissolved air. In 1824, René-Joachim-Henri Dutrochet, a French physiologist, discovered the phenomenon of osmosis in natural membranes [1]. In 1855, Adolf Eugen Fick, a German physiologist, introduced Fick’s law of diffusion, which describes the diffusion of a gas across a fluid membrane [2]. In 1861, Thomas Graham, a Scottish chemist, studied the diffusion of gases and laid the foundation of gas and vapor separation through polymeric membranes [3]. He could be called the father of modern dialysis, which is the usage that occupies the biggest share of the membrane market. In 1887, Jacobus Henricus van’t Hoff, a Dutch physical and organic chemist, proposed the famous van’t Hoff equation for osmotic pressure (π). This work was awarded the first Nobel Prize in Chemistry, in 1901 [4]. After these fundamental works, many other pioneering papers were published during the first half of the twentieth century; the “golden age” of membrane technology (1960–1980) began in 1960 with the invention by Loeb and Sourirajan [5] of the first asymmetric integrally skinned cellulose acetate reverse osmosis membrane.
Development of Simulated Moving Bed Reactor Using a Cation Exchange Resin as a Catalyst and Adsorbent for the Synthesis of Acetals
Published in Arup K. SenGupta, Ion Exchange and Solvent Extraction, 2007
Viviana M.T.M. Silva, Ganesh K. Gandi, Alírio E. Rodrigues
Some physical and thermodynamic properties of acetaldehyde, DME, DEE, ethanol, methanol, and water, available from literature, are presented in the Table 2.12. Thermodynamic properties, such as the enthalpy change of the reaction and equilibrium constant, are important for process design. Hence, to determine the above essential thermodynamic quantities, for both acetalization reactions, acetaldehyde–ethanol and acetaldehyde–methanol kinetic experiments were performed. Here, the experiments to measure the equilibrium constant for the acetalization reversible reaction were carried out in the batch reactor shown in Figure 2.3. The temperature dependency of equilibrium constant was determined from the Van’t Hoff equation. () lnKeq=ΔS°R=ΔH°R1T
Reactions Involving Gases
Published in David R. Gaskell, David E. Laughlin, Introduction to the Thermodynamics of Materials, 2017
Equation 11.10 is known as the van’t Hoff equation (Jacobus Henricus van’t Hoff, 1852–1911). The equation shows that the effect of temperature on Kp is determined by the sign and magnitude of ΔH° for the reaction. If ΔH° is positive, the reaction is endothermic and Kp increases with increasing temperature.If ΔH° is negative, the reaction is exothermic and Kp decreases with increasing temperature.
Adsorption of tetracycline by Nicandra physaloides (L.) Gaertn seed gum and Nicandra physaloides(L.) Gaertn seed gum/Carboxymethyl chitosan aerogel
Published in Environmental Technology, 2022
Liubo Li, Yanhui Li, Meixiu Li, Yong Sun, Huimin Wang, Mingfeii Cui, Wenshuo Xu
With the increase of temperature, the adsorption capacity of NPG and NPG/CMC aerogels for TC increased and decreased, respectively. Parameters such as entropy (ΔS), enthalpy (ΔH) and Gibbs free energy (ΔG) were obtained through the Van’t Hoff equation[47]. The expression is as follows T (K) and R (8.314 J/mol K) are absolute temperature and universal gas constant, respectively. The above parameters can be obtained by drawing a fitted straight line graph of ln(qe/ce) relative to 1/T. Table 3 listed all parameters. All values of ΔG were less than zero, indicating that NPG and NPG/CMC aerogels adsorption of TC was feasible and spontaneous. The enthalpy ΔH of NPG and NPG/CMC were positive and negative, respectively. The results showed that the adsorption of TC by NPG and NPG/CMC aerogels was endothermic and exothermic, respectively, which was consistent with the results obtained from Figure 6(a).
Chicken feathers derived materials for the removal of chromium from aqueous solutions: kinetics, isotherms, thermodynamics and regeneration studies
Published in Journal of Dispersion Science and Technology, 2022
Rupa Chakraborty, Anupama Asthana, Ajaya Kumar Singh, Renu Verma, Sreevidya Sankarasubramanian, Sushma Yadav, Sónia A. C. Carabineiro, Md. Abu Bin Hasan Susan
The thermodynamic parameters were determined using van’t Hoff equation. The chromium adsorption on CFs was observed at three different temperatures at 30, 40, and 50 °C (303, 313, and 323 K) in optimized conditions. The change in Gibbs free energy (ΔG0), change in entropy (ΔS0), and change in enthalpy (ΔH0), for the adsorption process were determined by the following equations.[71] where Kd is the thermodynamic equilibrium constant, CA is the equilibrium concentration of Cr(VI) ion adsorbed per litre on the CFs (mg/L), and CB is the equilibrium Cr(VI) ion concentration (mg/L). R is the universal gas constant (8.314 × 10−3 kJ/mol K) and T is the absolute temperature in Kelvin (K). The values of ΔS0 and ΔH0 can be obtained from the slope and intercept of lnKd versus 1/T van’t Hoff plot, found in Figure 8.