Study of Oxalic Acid Adsorption Isotherm on Activated Carbon: Verification of the Freundlich Isotherm Model

The process of solute adsorption is a vital phenomenon in physical chemistry and holds broad applications, particularly in water purification and catalytic processes. This study focuses on an adsorption isotherm analysis using activated carbon as the adsorbent and oxalic acid () as the solute. Adsorption involves establishing an equilibrium between the amount of adsorbate bound to the adsorbent's surface and its concentration in the solution at a constant temperature. Activated carbon is known to have a non-uniform (heterogeneous) surface. Therefore, the Freundlich Isotherm model—which is an empirical equation suitable for heterogeneous surfaces and capable of describing multilayer formation—is selected for verification and analysis in determining the adsorption capacity of this system. The main objective of this research is to quantitatively analyze the adsorption equilibrium data to assess the extent to which the Freundlich model can accurately describe the interaction of oxalic acid molecules with the activated carbon surface.