Adsorptive removal of aflatoxin B1 from water and edible oil by dopamine-grafted biomass chitosan–iron–cobalt spinel oxide nanocomposite: mechanism, kinetics, equilibrium, thermodynamics, and oil quality

Abstract

Currently, the use of magnetic physical adsorbents for detoxification is widely applied in the food industry; however, the fabrication of high-efficiency low-cost absorbents without damaging the nutritional quality of food is a major challenge. Herein, a simple, green, efficient, and cost-effective method for the magnetic solid-phase extraction of aflatoxin B₁ (AFB₁) from edible oils and aqueous matrices was developed using a dopamine-loaded biomass chitosan–iron–cobalt spinel oxide nanocomposite (DC/CFOS NC). The characterization, physicochemical processes, mechanism, and reusability of DC/CFOS were systematically evaluated in detail. It was found that the adsorption characteristic of DC/CFOS NC was accurately represented by the pseudo-second-order kinetics (k₂ = 0.199 g mg⁻¹ min⁻¹) and Freundlich isotherm models (K_f = 1.139 (mg g⁻¹) (L mg⁻¹), R² = 0.991)), and its adsorptive process is feasible, spontaneous, and exothermic. Benefiting from its high specific surface area, microporous structure, and polar/non-polar active sites, the as-prepared DC/CFOS exhibited an excellent adsorption performance for AFB₁ (50.0 μg mL⁻¹), as measured using the Freundlich isotherm model. The mechanistic studies demonstrated that the synergistic effects of the surface complexation and electrostatic interactions between the functional groups of DC/CFOS NC and AFB₁ were the dominant adsorption pathways. Besides, DC/CFOS exhibited negligible impacts on the nutritional quality of the oil after the removal process and storage. Thus, DC/CFOS NC showed sufficient efficacy and safety in the removal of AFB₁ from contaminated edible oil.