Spectroscopic and Thermodynamic Elucidation of COD Adsorption Mechanisms on a Porous Carbon-Based Resin

. Kinetic analysis followed the pseudo-second-order model, while the Freundlich isotherm best described the equilibrium behavior, indicating heterogeneous adsorption. Thermodynamic parameters confirmed that the adsorption process is spontaneous and endothermic. Spectroscopic and structural analyses revealed that COD removal is mainly governed by synergistic mechanisms including π-π interactions between aromatic pollutants and the carbon framework, hydrogen bonding with oxygen-containing functional groups, and pore filling within the hierarchical porous structure. These findings demonstrate the strong potential of porous carbon-based resins as efficient adsorbents for treating high-strength industrial wastewater.