Hierarchical Porous Aero-Cryogels for Wind Energy Enhanced Solar Vapor Generation

An integrated aero-cryogel (A-CG) monolith with hierarchical porous structure was developed by inter-crosslinking of cellulose nanofiber (CNF)/polylactic acid (PLA) nanocomposite aerogel and carboxymethyl cellulose (CMC) cryogel. The photothermal nanoparticles-enriched CMC cryogel phase served as a sunlight absorbing layer, exhibiting a broadband sunlight absorption of 98%. Due to the large amount of weakly bounded water molecules, the swelled CMC cryogel possessed a lower evaporation enthalpy than that of pure water, which facilitates water evaporation, while the nanocomposite aerogel phase acted as an excellent thermal insulator and afforded highly efficient water transport channels. Thus, the developed A-CG monolith supported by insulated polystyrene foam to protrude above the water surface, could reach an evaporation rate of 2.16 kg m-2 h-1 under an irradiation of 1 Sun (100 mw/cm2) with an efficiency of 93.6%. More remarkably, when the wind energy was imparted, an evaporation rate of 5.67 kg m-2 h-1 was achieved at a wind speed of 3 m s-1. The high-efficiency purification outcomes of various raw water demonstrate the great potentials of A-CG material in solar vapor generation.

A versatile platform of poly(acrylic acid) cryogel for highly efficient photothermal water evaporation

Besides absorbing light and holding heat, modulating real evaporation enthalpy of water is important for photothermal water evaporation but it is still in exploration.

Vacancy Formation Energy of Metals

In this work, we investigated and discussed the experimental and theoretical data of the vacancy formation energy Ev. The results of calculations in the continuum model of the solids and the model of interaction between a pair of neutral atoms, as well as the results of ab initio methods using various exchange – correlation functionals, are analyzed. It was found that the experimental and theoretical values of the vacancy formation energy have an adjusted coefficient of determination R2 close to 0.80. The relationship between the calculated vacancy formation energy and the sublimation enthalpy most closely corresponds to the relation Ev = ΔHs/3 for the results obtained on the basis of continuum model and model of interaction between a pair of atoms. The vacancy formation energy most closely correlates with the melting enthalpy ΔHm. The adjusting coefficient of determination R2 of this relation is 0.87 in comparison with 0.71 and 0.84 for the sublimation enthalpy and the evaporation enthalpy, respectively.

Модельная среда с тепловыми и транспортными свойствами жидкой воды

A model of a Frenkel gas-solid medium consisting of Н2О molecules and H3O + and OH- ions with the same density and concentration of particles as liquid water is considered. Particles make a thermal vibrational-diffusive motion, during which they collide, exchange protons and interconvert. Under the assumption that the medium is retained by the dipole-ion interaction forces, it was shown that the evaporation enthalpy H, specific heat C, and also the transport parameters of the medium --- self-diffusion coefficient D, viscosity eta, and thermal conductivity theta --- are close to the reference values ​​for liquid water throughout the interval of its existence (250-600 K).

Enthalpy of isopropanol adsorption on zeolite

The enthalpy of isopropanol adsorption on ZSM-5 (Zeolite Socony Mobil Framework Type MFI) was determined by the static adsorption method at the temperature range from 20°C to 100°C. Langmuir and Huttig models of equilibrium adsorption have been used to calculate the enthalpy of isopropanol adsorption at these conditions. Adsorption isotherms determined by the flow method at 20°C and 30°C have been also used in the calculations. The obtained values of isopropanol adsorption enthalpy were compared with the values of isopropanol evaporation enthalpy and with the results obtained from isopropanol and water desorption measurements with thermogravimetry and differential scanning calorimetry methods.