Determination of mesopore and macropore size in solids by nitrogen adsorption

What is it?

It is a technique that allows the determination of size of meso- and macro-pores in solid materials by gas adsorption. Using the BJH theory (Barrett, Joyner and Halenda) it is possible to calculate pore size and volume distribution by determining the volume of gas (in this case nitrogen) necessary to form molecular multilayers on the surface of a sample at a constant temperature (Liquid nitrogen temperature).
The amount of gas adsorbed depends the interaction between the gas and the sample, therefore, among other factors, the specific surface area depends on the nature of the sample.

What is it used for?

The gas adsorption method is the most used technique to determine the specific surface area. This technique allows the characterization of different materials, such as pharmaceuticals, catalysts, zeolites, among others ....

Equipment and working conditions

A Micromeritics ASAP 2000 equipment is used to determine the specific surface areas.
This equipment has two ports to do the degassing, where it is possible to control the temperature up to 350 ° C and one to perform the test, using liquid nitrogen to keep the temperature constant.
All aspects relating to the analysis as well as data acquisition are processed by computer.

Example of use

Pharmaceutical, paper and ceramic industries and research centers.