scholarly journals Positron Probing of Liquid-free Volume To Investigate Adsorption–Desorption Behavior of Water in Two-Dimensional Mesoporous SBA-3

2017 ◽  
Vol 121 (32) ◽  
pp. 17251-17262 ◽  
Author(s):  
Priya Maheshwari ◽  
Marek Gorgol ◽  
Agnieszka Kierys ◽  
Radosław Zaleski
Keyword(s):  
Free Volume ◽  
Two Dimensional ◽  
Adsorption Desorption

A molecular dynamics model of melting and glass transition in an idealized two-dimensional material I

1989 ◽  
Vol 329 (1608) ◽  
pp. 549-573 ◽  
Keyword(s):  
Molecular Dynamics ◽  
Thermal Expansion ◽  
Glass Transition ◽  
Free Volume ◽  
Dimensional Structure ◽  
Valuable Insight ◽  
Two Dimensional ◽  
Discrete Elements ◽  
Dynamics Model ◽  
Topological Features

In a preparatory study of structural relaxations and plastic flow in a two-dimensional idealized atomic glass, the process of melting and quenching through a glass transition has been studied by computer simulation using a molecular dynamics model. In this model, the transition from a solid to a melt was observed to take place when liquid-like structural elements composed of dipoles of five- and seven-sided Voronoi polygons percolate through the two-dimensional structure of distorted hexagons in the form of strings. Such dipoles constitute discrete elements of excess free volume within which liquid like behaviour is established in the sense of reduced cohesion or local elastic moduli. Upon quenching the melt, the percolation condition of liquid-like regions is retained for under-cooled melts between the melting point and a glass transition temperature below which the percolation condition is broken and the thermal expansion is sharply reduced. The simulation that has used empirical pair potentials characteristic of Cu and Zr has substantially underpredicted the melting and glass transition temperatures and overpredicted the thermal expansion of C u x Zr 1-x type glasses. These defects of the model can be partly attributed to the two-dimensional nature of the material, which stores larger concentrations of free volume than a corresponding three-dimensional material. In spite of these quantitative shortcomings, the model gives valuable insight into the topological features of the local atomic configurations at melting and upon vitrification.

Adsorption–Desorption and Transport of Water in Two-Dimensional Hexagonal Mesoporous Silica

2013 ◽  
Vol 117 (42) ◽  
pp. 21795-21802 ◽  
Author(s):  
Hideki Yanagihara ◽  
Kyohei Yamashita ◽  
Akira Endo ◽  
Hirofumi Daiguji
Keyword(s):  
Mesoporous Silica ◽  
Two Dimensional ◽  
Hexagonal Mesoporous Silica ◽  
Adsorption Desorption

On the kinetics of the Langmuir-type heterogeneous reactions

2011 ◽  
Vol 16 (4) ◽  
pp. 467-476 ◽  
Author(s):  
Vladas Skakauskas ◽  
Pranas Katauskis
Keyword(s):  
Steady State ◽  
Surface Coverage ◽  
Surface Reactions ◽  
Heterogeneous Reactions ◽  
The Other ◽  
Two Dimensional ◽  
Finite Difference Technique ◽  
Planar Surfaces ◽  
Adsorption Desorption ◽  
Kinetics Of

In this paper we investigate three two-dimensional in space mathematical models of the kinetics of unimolecular heterogeneous reactions proceeding onto planar surfaces. All models include the diffusion of the reactant from a bounded vessel towards an adsorbent, adsorption of the molecules of the reactant, their desorption, conversion (reaction) of the adsorbate into a product, instantaneous product desorption, and the diffusion of the product from the adsorbent into the same vessel. One of these models is based on the Langmuir-type kinetics of the surface reactions, the other one is based on the local steady-state value of the surface coverage, and the last one, in addition to the first model, involves the diffusion of the adsorbate along the adsorbent. Diffusivity of all species is assumed to be constant. Models were solved numerically by using the finite difference technique. By changing input parameters the effects of the rate constants of the reactant adsorption, desorption, and reaction and the influence of the surface diffusion of the adsorbate and approximation of the surface coverage by its steady-state value on the kinetics of surface reactions were studied numerically.

Graphene Oxide-Supported Two-Dimensional Microporous Polystyrene

2013 ◽  
Vol 1549 ◽  
pp. 25-29 ◽  
Author(s):  
Yi Ouyang ◽  
Dingcai Wu ◽  
Ruowen Fu
Keyword(s):  
Graphene Oxide ◽  
Energy Storage ◽  
Carbon Tetrachloride ◽  
Specific Surface ◽  
Atom Transfer Radical Polymerization ◽  
Surface Area ◽  
Nitrogen Adsorption ◽  
Two Dimensional ◽  
Desorption Energy ◽  
Adsorption Desorption

ABSTRACTIn this paper, a microporous-containing graphene oxide/polystyrene (M-GO/PS) was designed and prepared by surface-initiated atom transfer radical polymerization (SI-ATRP) of PS from GO surface and then crossrlinking by carbon tetrachloride. The structures of the molecular brush of PS and the related crosslinking M-GO/PS were determined by FTIR, TG, SEM and nitrogen adsorption-desorption analysis. The experimental results showed that PS molecular brush were successfully grown on to the surface of GO. After crosslinking, the PS component was crosslinked into many round nanoparticles with a diameter of 20-30 nm, and therefore the specific surface area of GO/PS obviously increased. This kind of porous M-GO/PS composite was promising for the application in adsorption-desorption energy storage areas.

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