Valorisation of Nance (Byrsonima crassifolia) Seed as Biosorbent for Tannic Acid Removal from Aqueous Solutions by Physicochemical and Structural Evidence

This study evaluated the potential of Nanche seeds as a bio-adsorbent for removing TA from aqueous solutions. Additionally, we inferred the interaction mechanisms involved in the adsorption process from physicochemical evidence, isotherm modelling, and ADI analysis. The Langmuir model best fit the experimental data (R2 = 0.999) across temperatures (20–60 °C). Thermodynamically, the process was endothermic and spontaneous, (∆H° = 10.11 ± 0.45 kJ/mol and ∆G° = −28.58 ± 1.03 kJ/mol), indicating that the interaction mechanisms were physical. The value of ∆S° (0.116 ± 0.003 kJ/mol·K), the Freundlich constant (n > 1), and data derived from ADI analysis of SEM micrographs that support the increased complexity and multifractal nature of the process. FTIR revealed surface changes in the adsorbent material attributable to the interactions between the seed and the TA. Extent of vibrations associated with carboxyl groups decreased after adsorption, which was attributed to low-energy interactions, such as π-π stacking, supporting physisorption interaction. The ki values increased linearly with temperature and TA concentration. This study used ideal adsorption systems to elucidate fundamental mechanisms, providing a foundation for future, more complex research. Nance seeds proved to be effective yet underutilized adsorbent material. Further studies are needed on its applicability in continuous processes and multicomponent matrices systems.