Experimental study on condition optimization of coal-to-biomethane enhanced by action of external electric field

In order to satisfy the increasing demand of energy and reduce the impact of greenhouse gases on the environment,the vigorous development and uilliza tion of coalbed methane has become increasingly important. The external electric field is an emerging technology that improves biomethane production and carbon diox ide capture capacity,which can improve substrate degradation rate and increase methane production effectively.In this paper,the effects of electrode materials and volta ges on the production of biomethane from coal was studied,the conditions for increasing production were optimized,and the effects of biodegradation on the structure of coal under the application of electric field were analyzed by Fourier infrared spectroscopy( FTIR).The results showed that the reactor with carbon felt as the anode and stainless steel as the cathode under the voltage of 1.2 V were the best condition for biogenic methane production from coal. The maximum methane yield per gram of C oal was an average of 96.9 μmol/g,which was 155% higher than 0 V.The results of FTIR revealed that the residual coal at 0 V was not significantly changed compared w ith raw coal after the gas production completed. However,under the application of an external electric field,the tensile vibration intensity of the stretching vibration of ea ch characteristic peak of the aromatic functional group in the residual coal is reduced after biodegradation. The ether oxygen bond and carboxyI and carbonyl groups in the oxygen-containing functional group of residual coal reduced significantly. The intensity of each characteristic peak in the aliphatic functional group was significantly I ower than that of the raw coal and the residual coal under 0 V conditions. These results show that under the application of an electric field,the biodegradation destroys t he aromatic ring structure,oxygen-containing groups and fat components of coal. The research results suggests that the application of an electric field can enhance bio genic methane from coal significantly,which lays the foundation for further increasing the coal-based biomethane production.