[Surface Area] Single-point and Multi-point BET Theories

Basic and simple introduction of the single-point BET, multi-point BET and the differences between of them.

[Surface Area] BET Theory, Equation and Relation with Langmuir Theory

The BET theory introduction and its plot meaning, also with the BET test steps. The BET is an extension of Langmuir surface area and the limitations.

[Porosity] Adsorption Hysteresis

It is widely accepted that there is a correlation between the shape of the hysteresis loop and the texture (e.g., pore size distribution, pore geometry, connectivity) of a mesoporous adsorbent. An empirical classification of hysteresis loops was given by the IUPAC, which is based on an earlier classification by de Boer.

[Porosity] Classification of Adsorption Isotherms

Based upon an extensive literature survey, performed by Brunauer, Demming, Demming and Teller (BDDT), the IUPAC published in 1985 a classification of six sorption isotherms.

[Porosity] Pore Size and Adsorption Potential

The shape of sorption isotherms of pure fluids on planar surfaces and porous materials depends on the interplay between the strength of fluid-wall and fluid-fluid interactions as well as the effects of confined pore space on the state and thermodynamic stability of fluids confined to narrow pores.

[Surface Area] The Frenkel-Halsey-Hill (FHH) Theory of Multilayer Adsorption

Physisorption at temperatures below the critical temperature Tc and in the complete wetting regime leads to the development of multilayer adsorption by approaching the saturation pressure Po. The BET theory describes adsorption of the first two or three layers in a satisfying way, but fails to assess correctly the range of the adsorption isotherm, which is associated with the development of thick multilayer films.

[Porosity] Physical and Chemical Adsorption

Depending upon the strength of the interaction, all adsorption processes can be divided into the two categories of chemical and physical adsorption.

[Surface Area] Surface Area from Particle Size Distributions

Although particles can assume all regular geometric shapes, and in most instances highly irregular shapes, most particle size measurements are based on the so-called ‘equivalent spherical diameter’.

[Porosity] Gas Adsorption Introduction

Gas adsorption is one of many experimental methods available for the surface and pore size characterization of porous materials.

[Surface Area] The Brunauer, Emmett and Teller (BET) Theory Equation

During the process of physical adsorption, at very low relative pressure, the first sites to be covered are the more energetic ones. Those sites with higher energy on a chemically pure surface reside within narrow pores where the pore walls provide overlapping potentials.

[Surface Area] The Langmuir Isotherm

The success of kinetic theories directed toward the measurements of surface areas depends upon their ability to predict the number of adsorbate molecules required to cover the solid with a single molecular layer.

[Labwares] Weight Conversion Factors Between Platinum and Other Precious Metals

weight conversion factors between platinum and other precious metals.

[Porosity] Adsorption in Mesopores

The sorption behavior in mesopores (2- 50 run) depends not only on the fluid-wall attraction, but also on the attractive interactions between fluid molecules. This leads to the occurrence of multilayer adsorption and capillary (pore) condensation. Pore condensation is the phenomenon whereby a gas condenses to a liquid-like phase in a pore at a pressure Pless than the saturation pressure Po of the bulk liquid.

[Porosity] Adsorption in Microporous Materials

According to IUPAC (International Union of Pure and Applied Chemistry), pores are classified as macropores for pore widths greater than 500 A, mesopores for the pore range 20 to 500 A and micropores for pore widths less than 20 A.

[Surface Area] What are Chemisorption and Physisorption Differences

The main differences between chemisorption and physisorption is: chemisorption may occur only in a monolayer on a surface, it is unilayer, directionial and strong; whereas physisorption is usually accompanied by multilayer adsorption, it is weak, non-directtional and non-specific, depending upon the temperature.