Effect and mechanism of anti-oxidant lipoic acid on coal spontaneous combustion
In order to study the inhibitory effect of antioxidant lipoic acid(LA)on the sponta-neous combustion of coal oxidation,the effect of LA on the spontaneous combustion tendency of coal was investigated by programmed heating experiment,and the inhibitory effect of LA and chlorine salt inhibitor was compared,and the changes of free radical type,concentration and surface functional group in coal before and after LA were analyzed by electron spin reso-nance spectroscopy(ESR)and Fourier infrared spectroscopy(FTIR).The experimental results show that different mass fraction of LA(1％,2％,3％and 4％)can inhibit the sponta-neous combustion process of coal,and the CO release concentration and oxygen consumption of coal samples after the coal sample with a mass fraction of 3％LA treatment are minimal,and the inhibitory effect is significantly better than that of the physical inhibitors CaCl2 and MgCl2 at the same concentration.The reactivity and relative concentration are lower than those of raw coal,and the two inhibitors could inhibit the reaction of-CH3 and-CH2-during coal oxidation and reduce the formation of-C=O and-OH.However,no matter from the effect of resisting or the temperature range of resisting,the inhibitory effect of LA is always stronger than that of MgCl2,and the mechanism of action of the two inhibitors is different.MgCl2 is used to inhibit the oxidation reaction of coal by oxygen barrier moisturizing action before 80 ℃,and LA fundamentally inhibits the initiation and progression of free radical chain reaction by reducing the type and relative concentration of free radicals in the reaction.According to the experimental results,it is inferred that oxidized LA and reduced DHLA can be used as hydro-gen donors,continuously consuming hydroxyl radicals and peroxide radicals in the coal oxida-tion process,neutralizing free carbon radicals and carbon-oxygen radicals,thereby reducing the concentration and reactivity of free radicals in the whole chain reaction process,and blocking the occurrence of coal-oxygen recombination.
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