sorptionkäyrät

Sorption käyrät, or sorption curves, represent the relationship between the amount of a solute that a sorbent (solid, liquid or gas phase) can adsorb or absorb and the concentration or activity of that solute in the surrounding phase. The curves are generated by systematically varying the solute concentration and measuring the equilibrium quantity adsorbed or absorbed. In adsorption, the sorbent surface is involved, whereas in absorption the solute penetrates into the bulk of the sorbent. The resulting functions are often plotted in terms of mass of solute per mass of sorbent versus equilibrium concentration, and they can be linear (e.g., for very dilute systems) or nonlinear, reflecting complex physicochemical processes.

The most common models for fitting sorption data are the Langmuir and Freundlich equations. The Langmuir model assumes a finite number of identical adsorption sites and no interaction between adsorbed molecules, yielding a hyperbolic uptake curve that saturates at a maximum adsorption capacity. The Freundlich equation is empirical and describes heterogeneous surface energies, showing adsorption increases with concentration but without an upper limit. Other models, such as the Temkin, Dubinin–Radushkevich, and BET equations, are applied when specific adsorption mechanisms or multilayer adsorption are important. Choosing the appropriate model depends on the sorbent type, the solution chemistry, and the expected adsorption dynamics.

Sorption curves are essential tools in environmental engineering, water treatment, catalysis, pharmaceuticals, and material science. They inform the design of adsorption columns, the estimation of contaminant removal efficiencies, and the calculation of regeneration energies. By integrating sorption data with kinetic models, practitioners can predict transient behaviors under non‑equilibrium conditions. Accurate sorption curves enable optimization of sorbent selection, dosing strategies, and process scaling in both laboratory and industrial settings.