Surface Area Analyzer (SSA)

Working principle & Instrumentation 

SAA instrumentation 

The SSA (Surface Area Analyzer) is used to measure the specific surface area of a material, providing information about its porosity and the extent of available surface for chemical interactions. 

SAA quantifies the surface area by adsorbing gas molecules onto the material's surface and measuring the amount adsorbed. The data is then used to calculate the specific surface area. SAA typically consists of a degas system to remove adsorbed gases from the material, a sample cell where adsorption occurs, and a detection system to measure the adsorbed gas quantity. Instruments may use various inert and some other adsorptive gases like nitrogen. Principle is the gas adsorption onto the sample's surface. The amount of gas adsorbed is directly related to the surface area. The BET (Brunauer, Emmett, Teller) theory is commonly employed, which assumes the formation of a monolayer (as Langmuir theory) or multilayer of gas molecules on the surface. By analyzing the gas adsorption isotherm, the surface area of the material can determined accurately.

It is essential for characterizing materials with porous structures, like catalysts, adsorbents, and powders. It provides valuable information for researchers and industries involved in areas such as catalysis,  material science, environmental science etc. Pore volume and pore area distributions in the mesopore and macropore ranges by the BJH (Barrett, Joyner, Halenda) method of gas adsorption and desorption using a variety of thickness equations including a user-defined, standard isotherm (graph of gas adsorpition vs relative pressure).

Sample Preparation Samples need to be prepared by degassing to remove any previously adsorbed gases or contaminants. This is crucial for accurate measurements. Samples are often finely powdered or have a high surface area, such as porous materials like zeolites or activated carbon.

Results interpretation The specific surface area is determined by analyzing the quantity of gas adsorbed at various pressures. A plot of adsorption isotherm (adsorbed gas versus pressure) is created. Specific surface area is calculated using models such as the BET (Brunauer, Emmett, and Teller) equation systematically and provide BET isotherm gas adsorption graph. The BET theory is commonly employed, which assumes the formation of a monolayer (as langmuir theory) and can be multilayer of gas molecules on the surface.

SAA graph