Inhibitory effect of green antioxidants acting on surface groups and structure on lignite

To contain coal fires, three green antioxidants of plant extract which cover resveratrol (Res), tea polyphenols (TP), and β-carotene (β-car) are investigated in this paper, and their inhibitory effects on surface groups and structure are revealed. X-ray diffraction test tells that antioxidants exert a slight augment of d100 and Lc and are able to destroy the unstable side chains to some extent. Though coal samples are affected by antioxidants, minimal differences of aromatic structure have been proved. Fourier-transform infrared spectroscopy technique is employed and a new concept of influence sensitivity value is introduced. The results indicate that antioxidants and addition amounts have an impact on various groups, and the majority of groups tend to be inhibited within 3 wt% addition. Further, the optimal inhibitory concentration of Res, TP, and β-car is 1 wt%, 3 wt%, and 1 wt%, respectively. Combined with gaseous indexes, CO2 emissions of Res and TP exhibit a wave variation under 100 °C, and exponential growths of others occurred twice is acquired. Antioxidants can bring out the decline of apparent activation energy (Ea), and TP worked most brilliantly and it increases Ea by 7.503 kJ/mol. In summary, the order of inhibitory effect is TP > Res > β-car.