Morphology Effect on the Kinetic Parameters and Surface Thermodynamic Properties of Ag3PO4Micro-/Nanocrystals

Considerable effort has been exerted using theoretical calculations to determine solid surface energies. Nanomaterials with high surface energy depending on morphology and size exhibit enhanced reactivity. Thus, investigating the effects of morphology, size, and nanostructure on the surface energies and kinetics of nanomaterials is important. This study determined the surface energies of silver phosphate (Ag3PO4) micro-/nanocrystals and their kinetic parameters when reacting with HNO3by using microcalorimetry. This study also discussed rationally combined thermochemical cycle, transition state theory, basic theory of chemical thermodynamics with thermokinetic principle, morphology dependence of reaction kinetics, and surface thermodynamic properties. Results show that the molar surface enthalpy, molar surface entropy, molar surface Gibbs free energy, and molar surface energy of cubic Ag3PO4micro-/nanocrystals are larger than those of rhombic dodecahedral Ag3PO4micro-/nanocrystals. Compared with rhombic dodecahedral Ag3PO4, cubic Ag3PO4with high surface energy exhibits higher reaction rate and lower activation energy, activation Gibbs free energy, activation enthalpy, and activation entropy. These results indicate that cubic Ag3PO4micro-/nanocrystals can overcome small energy barrier faster than rhombic dodecahedral Ag3PO4micro-/nanocrystals and thus require lower activation energy.

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Excellent catalysis of TiO2 nanosheets with high-surface-energy {001} facets on the hydrogen storage properties of MgH2

Nanoscale ◽

10.1039/c8nr10275a ◽

2019 ◽

Vol 11 (15) ◽

pp. 7465-7473 ◽

Cited By ~ 27

Author(s):

Meng Zhang ◽

Xuezhang Xiao ◽

Xinwei Wang ◽

Man Chen ◽

Yunhao Lu ◽

...

Keyword(s):

Activation Energy ◽

Surface Energy ◽

Hydrogen Storage ◽

High Surface ◽

Hydrogen Storage Properties ◽

System P ◽

Tio2 Nanosheets ◽

High Surface Energy ◽

Storage Properties

Anatase TiO2 nanosheets with exposed {001} facets were used to improve the kinetic performance and reduce the activation energy of MgH2 system.

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Study of adhesion-active surface structures in P6M5 high-speed steel

Industrial laboratory Diagnostics of materials ◽

10.26896/1028-6861-2018-84-12-40-44 ◽

2018 ◽

Vol 84 (12) ◽

pp. 40-44 ◽

Cited By ~ 1

Author(s):

V. A. Kim ◽

Ch. F. Yakubov ◽

E. V. Shchelkunov ◽

E. V. Samar

Keyword(s):

Free Energy ◽

Surface Energy ◽

Metal Cutting ◽

Chemical Potential ◽

High Surface ◽

Active Surface ◽

Surface Structures ◽

Active Centers ◽

Structural Formation ◽

High Surface Energy

Adhesive processes are the main reason for wear of the metal-cutting tool. Adhesion-active surface structures (micro and meso-scale zones with increased density of defects having a crystal structure and high surface energy) can be identified by treating the surface with reactants by analogy with etching of a metalgraphic shlif. The level of free energy of the structural formation was estimated by the degree of darkening (dark gray color intensity) of the microstructure revealed by etching. The degree of darkening can be described and rankes quantitatively using color segmentation. Most specialized programs for metallographic image processing contain similar algorithm. The images were studied using the following indices of the structural arrangement of adhesion-active centers: the density of microstructural objects with a high value of the free energy, their relative surface area and dark gray color coefficient. A high value of the coefficient corresponds to the larger chemical potential. A comparative analysis of the character of distribution of adhesion-active zones in the surface structures of the crude and tempered P6M5 highspeed steel revealed that tempered structure contains more structural elements with high free energy (or chemical potential). Their distribution on the surface forms local zones of increased hardness, possessing high surface energy, as well as adhesion-active centers acting as potential foci for the formation of strong islet growths or zones of formation of stable adsorption films.

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Bio-mimicking hybrid polymer architectures as adhesion promoters for low and high surface energy substrates

Journal of Industrial and Engineering Chemistry ◽

10.1016/j.jiec.2021.05.004 ◽

2021 ◽

Author(s):

Monisha Baby ◽

Vijayalakshmi K. Periya ◽

Bhuvaneshwari Soundiraraju ◽

Nisha Balachandran ◽

Suchithra Cheriyan ◽

...

Keyword(s):

Surface Energy ◽

High Surface ◽

Hybrid Polymer ◽

Energy Substrates ◽

Adhesion Promoters ◽

Polymer Architectures ◽

High Surface Energy

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Kinetics and thermodynamic properties related to the drying of 'Cabacinha' pepper fruits

Revista Brasileira de Engenharia Agrícola e Ambiental ◽

10.1590/1807-1929/agriambi.v20n2p174-180 ◽

2016 ◽

Vol 20 (2) ◽

pp. 174-180 ◽

Cited By ~ 8

Author(s):

Hellismar W. da Silva ◽

Renato S. Rodovalho ◽

Marya F. Velasco ◽

Camila F. Silva ◽

Luís S. R. Vale

Keyword(s):

Experimental Data ◽

Activation Energy ◽

Free Energy ◽

Thermodynamic Properties ◽

Gibbs Free Energy ◽

Removal Rate ◽

Effective Diffusion ◽

Drying Time ◽

Three Samples ◽

Different Temperatures

ABSTRACT The objective of this study was to determine and model the drying kinetics of 'Cabacinha' pepper fruits at different temperatures of the drying air, as well as obtain the thermodynamic properties involved in the drying process of the product. Drying was carried out under controlled conductions of temperature (60, 70, 80, 90 and 100 °C) using three samples of 130 g of fruit, which were weighed periodically until constant mass. The experimental data were adjusted to different mathematical models often used in the representation of fruit drying. Effective diffusion coefficients, calculated from the mathematical model of liquid diffusion, were used to obtain activation energy, enthalpy, entropy and Gibbs free energy. The Midilli model showed the best fit to the experimental data of drying of 'Cabacinha' pepper fruits. The increase in drying temperature promoted an increase in water removal rate, effective diffusion coefficient and Gibbs free energy, besides a reduction in fruit drying time and in the values of entropy and enthalpy. The activation energy for the drying of pepper fruits was 36.09 kJ mol-1.

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