Thermodynamic and Kinetic Studies of Curcumin Adsorption on Corn Cob Powder

This study investigates the potential of native and alkali-treated corn cob powders as cost-effective adsorbents for curcumin, a natural polyphenolic compound with immense pharmaceutical importance. The adsorption experiments were conducted by varying parameters, such as initial curcumin concentration, the amount of corn cob, and temperature. Alkali treatment altered the surface functional groups of corn cob powder, resulting in enhanced adsorption efficiency (65.12%) compared to the native corn cob powder (52.17%). Maximum adsorption capacity and per cent adsorption were achieved at an initial concentration of 0.5 µg mL^-1, a temperature of 30°C, and an adsorbent amount of 12 g L^-1. Kinetic analysis revealed that the adsorption process followed a pseudo-first-order model, suggesting physisorption is a dominating phenomenon. Equilibrium data were best described by the Freundlich isotherm, confirming a heterogeneous and multilayer adsorption mechanism. Thermodynamic analysis showed negative Gibbs free energy (ΔG) values, demonstrating spontaneity, while the negative enthalpy (ΔH) values confirmed an exothermic nature of the process. Overall, these findings highlight corn cob powder as a low-cost, renewable source with strong potential as a sustainable adsorbent for curcumin. This approach not only enhances curcumin stability and bioavailability but also contributes to circular-economy goals by valorizing agricultural waste for pharmaceutical applications.