In vitro aflatoxin adsorption by means of a montmorillonite silicate. A study of adsorption isotherms

To evaluate the affinity and capacity of a feedstuff additive, a montmorillonite silicate, to adsorb the four major naturally occurring aflatoxins, a study of the Langmuir and Freundlich adsorption isotherms was carried out. The Freundlich isotherm fits the data better than the Langmuir isotherm. The data reveal adsorptions of about 1000 μg aflatoxin B1 g−1 montmorillonite, 425–450 μg aflatoxin G1 g−1, 230 μg aflatoxin G2 g−1 and 200 μg aflatoxin B2 g−1. The superior results obtained with the Freundlich isotherm suggest either the presence of a heterogeneous sorbent surface, or the co-existence of different adsorption mechanisms, or both phenomena at the same time, the saturation of the adsorbent material being far from complete.