equilibrium isotherm

An equilibrium isotherm describes the relationship between the amount of a substance that a material can absorb and the concentration of that substance in contact with it, once a stable state is reached. Think of it as a balance point: the rate of the substance entering the material equals the rate leaving, resulting in a constant amount absorbed at a specific concentration. This concept helps us understand how materials like activated carbon or filters capture pollutants or gases, revealing their capacity and efficiency for a particular substance under steady conditions.