Biosorption of zinc ions (Zn<sup>2+</sup>) by dead <i>Aspergillus flavus</i> link mycomass: isotherm, kinetics, and thermodynamic studies

The present study explores the potential of dead <italic>Aspergillus flavus</italic> mycomass (DAFM) as an effective, eco-friendly, and low-cost myco-biosorbent for the removal of Zn²⁺ ions from contaminated aqueous environments. DAFM, characterized by its chemically diverse surface and abundance of functional groups, offers significant promise for the removal of metal ions. The study systematically optimized key operational parameters − including biomass age, particle size, temperature, contact time, DAFM dosage, and initial Zn²⁺ concentration − to identify the most favorable conditions for maximum biosorptive efficiency. Advanced characterization techniques, including FT-IR spectroscopy, confirmed the active participation of functional moieties such as hydroxyl, carboxyl, and amide groups in Zn²⁺ binding, underscoring the role of physicochemical interactions in the adsorption process. The maximum adsorption capacity (<italic>q_max</italic> = 65.69 mg·g⁻¹) obtained with Langmuir's isotherm model exhibited a close relationship with experimental adsorption capacity. Kinetic analysis supported the pseudo-second-order model, indicating chemisorption as the dominant mechanism, while thermodynamic evaluation revealed that the process is spontaneous and endothermic, with increased randomness at the solid-liquid interface. Furthermore, equilibrium modeling demonstrated the system's conformity to the Langmuir isotherm, highlighting the monolayer adsorption capacity of DAFM. Overall, the findings affirm the potential utility of DAFM in industrial effluent treatment, particularly in sectors releasing zinc-laden wastewater. This study lays the groundwork for scalable applications of fungal biomass in biosorption technologies, contributing to the development of sustainable and cost-effective water purification systems suitable for use in resource-limited settings.