Influence of microwave treatment on the combustibility of tobacco and its kinetic analysis
Microwave treatment can promote the expansion of tissue structure of tobacco leaves and improve their combustibility. To study the structure and combustibility of tobacco leaves treated with microwave for different durations, scanning electron microscope combining with simultaneous thermal analysis was employed in this study. The kinetics at volatile component evolution stage and coke combustion stage during tobacco combustion were analysed. The results showed that: 1) The structure of tobacco leaves expanded gradually with the increase of microwave treatment duration. The tissue of tobacco leaves expanded abundantly and the cross-sectional width of tobacco leaves reached its maximum when the duration of microwave treatment was 55 seconds. 2) The combustion characteristic index, Sn value, of treated tobacco leaves in N2 or N2/O2 atmosphere increased first and then decreased with the increase of microwave treatment duration, and Sn value reached its maximum when the duration of microwave treatment was 55 seconds. It indicated that microwave treatment improved the combustion and pyrolysis performance of tobacco leaves, however the combustibility of tobacco leaves deteriorated once the duration of microwave treatment was longer than 55 seconds. 3) The main thermal weight loss phases of combustion reaction and pyrolytic reaction of tobacco leaves were analysed with Coats-Redfern method and Malek method, and their kinetic analysis was conducted by F1 kinetic model. The full tissue structure expansion and best combustibility of tobacco leaves have been achieved by microwave treatment for optimal duration, which would provide a theoretical reference for the design and development of tobacco products.