| dc.description.abstract | Smectite clay has been shown in studies over the past 20 years to sorb aflatoxin B1
(AfB1) in animal feed and thereby reduce its toxic influence on animals.
In this study, 20 smectite samples were selected from industrial products or reference
minerals. In the initial steps, it was shown that AfB1 entered the interlayer galleries of
smectites and a 10-fold range in sorption ability was observed in a set of 20 smectite
samples. Yet, it was not clear which clay properties (CEC, pH, base saturation) influenced
this variation.
In an effort to further explore properties that might influence the sorption of AfB1, three
good sorbent samples were chosen from our set of 20 samples along with one sample of
low sorption capacity. Those samples were fractionated into sand, silt, coarse clay (CC),
and fine clay (FC) fractions. From all sample fractions, sorption isotherms and X-ray
diffraction patterns were obtained. Additionally, a vermiculite and a palygorskite were
examined with regard to sorption capacity. Concentration of smectite and their adsorption
test suggest that differences in smectite composition are responsible for difference in
sorption, not so much their relative abundance or other mineral phases. Initial infrared
analysis indicates that weathered aluminous smectites, which have no octahedral iron or
magnesium, belong to the poor AfB1 sorbents.
Palygorskite and vermiculite are not effective sorbents.
Based on the findings in this study, tentative quality criteria of sorbent selection for their
use in animal feed were established. These criteria are: pH between 6.5 and 8.5, CEC > 75cmolc/kg, organic carbon < 2.5 g/kg, expression of XRD smectite peak and AlFeOHbending
in FTIR and Langmuir adsorption capacity for AfB1 > 0.40 mol/kg. | en |
