High physical properties of cashew nut shell biochars in the adsorbtion of mycotoxins
2019
Ahmadou, Abderahim | Napoli, Alfredo | Durand, Noel | Montet, Didier
Biochars were produced from cashew nut shell by pyrolysis on tubular oven at 400, 600 and 800°C.They were thenanalyzed and characterized (CHN, volatiles and pH);andwere tested at different pH (4.15, 6.54 and 9.05) under different adsorption conditions (filtration and stirring) for their ability tocapture aflatoxins and ochratoxin A (OTA). Above 25 mg of biochar in 5 mL of water-methanol mixturecontaining the mycotoxins (aflatoxins and OTA), all biochars adsorbedup to 100% of the aflatoxins at all pH (4.15, 6.54 and 9.05) and under all conditions (filtration or stirring) and pyrolysis temperature.Biochars also showed no effect on aflatoxins adsorption. Great differences were observed for the adsorption rates of OTA in function of the studied conditions. The adsorption efficiency of biochar for OTA increased with the increase of the pyrolysis temperature, which increases the specific surface area. The method used (filtration or stirring) had a strong influence on the adsorption rate, ranging from 29% by filtration up to 52% for 1000 mg of a biochar in 5 mL of water-methanol solution;and stirring increasedthe adsorption rate. In general, pH had less effect on the adsorption rate of OTA (2-5%). OTA best adsorption rate was observed for biochar produced at 800°C. The affinity between biochars and aflatoxins is very strong because atthe same experimental conditions and equal masses, biochars adsorb more aflatoxins than OTA (5 times more).
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