Sorptiokäyriä

Sorptiokäyriä, often translated as sorption isotherms, are graphical representations that describe the relationship between the amount of a substance adsorbed onto a solid surface (adsorbate) and the equilibrium pressure or concentration of the adsorbate in the surrounding fluid (gas or liquid) at a constant temperature. These curves are fundamental in understanding adsorption phenomena and are widely used in fields such as chemistry, materials science, and environmental engineering.

There are several types of sorption isotherms, each characterized by a distinct shape and indicative of different adsorption mechanisms. The most common classifications are based on the IUPAC (International Union of Pure and Applied Chemistry) system, which includes Type I through Type VI isotherms. Type I, for example, is characteristic of monolayer adsorption, where a limited number of adsorption sites are available. Type II and Type III isotherms often represent multilayer adsorption, with Type II showing strong adsorbate-adsorbent interactions and Type III indicating weaker interactions. Types IV and V exhibit a hysteresis loop, suggesting capillary condensation within porous materials. Type VI represents stepwise multilayer adsorption.

The data for constructing sorption isotherms is typically obtained through experimental measurements where the pressure or concentration of the adsorbate is varied while maintaining a constant temperature, and the amount adsorbed is measured at equilibrium. Analyzing the shape and parameters of these curves allows researchers to determine properties of the adsorbent, such as its surface area, pore size distribution, and the strength of interaction with specific adsorbates. This information is crucial for designing and optimizing processes like gas storage, separation technologies, and catalyst design.