Pyrolytic Conversion of Vomitoxin-Contaminated Corn into Value-Added Products

Abstract

Deoxynivalenol (DON) (also called vomitoxin) is a mycotoxin caused by pathogens that periodically contaminate crops such as maize, wheat, barley, oats, and rye, making them unusable. We explored pyrolysis as a process for the decontamination of vomitoxin-corn grains and their transformation into value-added products. Pyrolysis was carried out in a bench-scale batch reactor at maximum temperatures between 450 and 650 °C. This resulted in the total destruction of DON, from 5–7 ppm in raw corn grains to non-detectable levels in the treated bio-char. The effect of pyrolysis conditions, including temperature and heating rate, on the conversion of toxic corn grains was investigated. The maximum bio-oil yield was achieved at 650 °C (47 wt.%). The co-products were bio-char (29 wt.%) and non-condensable gases (24 wt.%). Acetic acid and levoglucosan were the two major valuable components in the bio-oil, corresponding to 26 g/kg and 13 g/kg of bio-oil, respectively. The bio-chars were analyzed and upgraded by physical activation using CO2 at 900 °C. Activation increased the bio-char surface area to 419 m2g−1 and promoted pore development, which was verified by SEM. Proximate analysis illustrated that stable carbon increased to 88.8% after activation compared to 10.9% in the raw corn. FT-IR results showed that the thermally unstable functional groups had been completely eliminated after activation. All characterization results confirmed that the activated corn bio-char has excellent potential for adsorption processes. The HHV of the non-condensable gas stream was 16.46 MJ/Nm3, showing the potential application of this product as an energy source.