Effect of heat treatment on efficacy of Thai bentonite for adsorption of aflatoxin B1 in vitro

Abstract

This research evaluated the effects of heat treatments on the efficacy of Thai bentonite (TBN) for adsorption of aflatoxin B1 (AfB1) in vitro. The TBN clays were ground to sizes less than 40, 60, 100 and 200 μm and heated for 1 hour at eleven heating temperatures at 25°C and from 100°C to 1000°C, at increments of 100°C. Clays were mixed separately with 5 ppm AfB1 solution and shaken at 1,000 rpm for 24 hours. Adsorption capacities for AfB1 by the TBN clays were determined using a UV-spectrophotometer. Results revealed that adsorption capacities were significantly increased, when temperatures reached 400°C and 500°C as compared to lower temperatures (p<0.05). The highest adsorption capacity was observed in clay heated at 600°C, which was significantly greater than at other temperatures (p<0.05). Significantly lower adsorption capacities were observed in the clays heated at 800°C, 900°C, and 1000°C. Furthermore, sizes of the TBN were not significantly related to the adsorption capacities among the clay samples (p>0.05). The results support the conclusions that TBN can efficiently adsorb AfB1 in vitro and heating the clay at optimal temperatures (600°C) can increase the adsorption capacity for AfB1.