China
Africa
Explore chapters and articles related to this topic
Interfacial Catalysis at Oil/Water Interfaces
Published in Alexander G. Vdlkdv, Interfacial Catalysis, 2002
The position of the crucial equilibrium (2) is determined by relation of the energies of solvation and hydration of the anions X-and Y-in the organic and aqueous phases. Since for inorganic anions the energy of hydration is usually much higher, this is the factor governing the equilibrium (2); thus, ions of high hydration energy (having high charge density) stay preferentially in the aqueous phase. As a consequence,
Electro-chemomechanical couplings
Published in Benjamin Loret, Fernando M. F. Simões, Biomechanical Aspects of Soft Tissues, 2017
Benjamin Loret, Fernando M. F. Simões
The standard hydration energy is measured as the enthalpy ΔH yielded (in the form of heat) when the ion in gaseous form is immersed in water. The total energy released (when ΔH < 0) however should involve also the change of internal structure of the chemical. The quantity that gives a measure of the order of the structure is the entropy S. Entropy increases as disorder increases. Therefore the variation of entropy from the gaseous phase to the hydrated state where motions are restrained by the ion-dipole bonds is certainly negative, ΔS < 0. The total measure of energy that is released (absorbed) during the process is the variation of free enthalpy ΔG (also called chemical potential) equal, at constant temperature, to ΔH − T ΔS. A process is said to be spontaneous, and exergonic, if ΔG < 0. Despite the fact that ΔS < 0, hydration is exergonic. For a cation M of valence z, () hydrationspontaneous if ΔG < 0Mz++nH2O⇌M(H2O)nz+,
Dual-imaging-mode smart hydrogel information platform for illumination-independent covert decryption and read
Published in International Journal of Smart and Nano Materials, 2022
Junjie Wei, Long Li, Rui Li, Qingquan Liu, Zejun Yan, Tao Chen
SAT is a kind of phase change materials with high enthalpy of latent heat, and the crystallization of supercooled SAT solution is accompanied by the release of latent heat because the lattice energy is less than the hydration energy. Therefore, the smart hydrogel containing the supercooled SAT also possesses the similar responsive exothermal behavior after crystallization. As shown in Figure 5a, the dynamic temperature maps of the supercooled hydrogel with various EG content were recorded by infrared camera. Due to the quick release of latent heat, the maximum temperature of the entire smart hydrogel with 2 wt% EG rapidly increased from ambient temperature to ~47.7°C in 60 s, while the 10 wt% EG-based smart hydrogel only increased to 34.2°C due to the lower crystallization rate and slower heat accumulation (difference value between obtained heat and dissipated heat). After the temperature reached the highest value, it dropped slowly as the dissipation of heat. Besides, the real-time temperature of the initial crystallization position in the smart hydrogel shows a similar phenomenon. As shown in Figures 5 b and c, the maximum raised temperature (∆T) and heating rate at the initial crystallization position decreased gradually as the increasing EG content because of the influence from crystallization rate. This great difference in hydrogel’s temperature exhibits a potential application in thermal-imagery-based information platform.
Study on the metakaolin-based geopolymer pervious concrete (MKGPC) and its removal capability of heavy metal ions
Published in International Journal of Pavement Engineering, 2021
Xiao Chen, Zidong Niu, Haoyu Zhang, Yuguang Guo, Min Liu, Mingkai Zhou
In order to further investigate the effect of compositions of MKG binder on the adsorption of heavy metal ions, the distributions of Pb2+ and Cr3+ on the surface of MKG binder were measured by EDS. The samples were obtained from the inner walls of connected pore with the similar size in M1, M2, and M3. The results are presented in Figure 13. The different colours of pixel represent different elements, and the number of pixels indicates the amount of elements contained in the MKG binder surface. In Figure 13, the purple, green and black pixel represented the Pb, Cr and unallocated elements, respectively. The surface of MKG binder of M1 contained 49% of the heavy metal ions (as Figure 13. EDS-M1), whereas that of M2 only contained43% (as Figure 13. EDS-M2) and that of M3 contained38% (as Figure 13. EDS-M3). These finding are consistent with the results in Figure 10. Therefore, it can be concluded that the adsorption of heavy metal ions (including Pb2+ and Cr3+) on the MKG binder is remarkably affected by the mole ratio of SiO2/Al2O3 of MKG remarkably. Moreover, with the same mole ratio of SiO2/Al2O3, the adsorption of Pb2+ is higher than that of Cr3+. This may be because the Pb2+ ion has a smaller hydrated radius and a lower free hydration energy (Cheng et al. 2012).
The Formation of Me(AOT)n Micelles as Nanoreactors, Crystallizers, and Charging Agents: Cation-Exchange Solvent Extraction versus Direct Injection Solubilization
Published in Solvent Extraction and Ion Exchange, 2020
Alexander I. Bulavchenko, Tatyana Yu. Podlipskaya, Marina G. Demidova, Evgeniya A. Terzi, Darya I. Beketova, Nina F. Beisel
The determining factor in injection solubilization processes is primarily the hydration of the micelle-forming surfactant and introduced ions. In the absence of ions, the maximum solubilization of pure water is obtained (Figures 4(a), 5(a) and 6(a)), which is attributed to the maximum hydration of the surfactant. Water molecules directly bound to surfactant molecules (the so-called primary bound ones)[34,35] interact with other molecules (secondary bound, etc.) via the formation of hydrogen bonds up to the formation of an aqueous core with water molecules exhibiting bulk properties. During injection solubilization of aqueous solutions of salts, hydration of surfactant molecules decreases because the salt ions are also hydrated and, at a limited number of water molecules, compete for them with the surfactant. An increase in the salt concentration in the injected solution decreases hydration of the surfactant, thus diminishing the solubilization capacity of micellar solution. Accordingly, the higher is the hydration energy of the introduced ion, the lower is the solubilization capacity. Doubly- and triply-charged cations are hydrated stronger than singly-charged ones (Table 1), so they are solubilized much more weakly, which is true for similar, for example 1 M, solutions of the salt.