Influence of layer charge origin and layer charge density of smectites on their aflatoxin adsorption

Similar effect of the exchangeable cations was observed in all smectites, but significant differences in the aflatoxin adsorption capacity were observed among the smectites. The octahedrally charged smectites showed higher aflatoxin adsorption than the tetrahedrally charged smectites. The aflatoxin-smectite bonding mechanism was not affected by the layer charge origin or density. Optimal layer charge density was required to have sufficient non-polar sites on the smectite for aflatoxin molecules. High-charge-density smectites had low adsorption capacity and binding affinity for aflatoxin, but aflatoxin adsorption on these smectites can be improved by reducing the layer charge density of the clay mineral. Smectites with octahedral charge increased the interlayer accessibility of aflatoxin molecules. The octahedral cation composition had a negligible effect on the aflatoxin adsorption capacity of smectites.