In order to deeply investigate the role of potassium in modifying thermal behavior and burning characteristics of reconstituted tobacco sheet (RTS), electrodialysis (ED) technology was employed at first to remove the main ions in the tobacco extract to reduce interference of endogenous ions. Characterization on thermal behavior of RTS treated with three organic (acetate, malate and citrate) potassium salts and three inorganic (chloride, sulfate and phosphate) potassium salts was then performed using thermogravimetric analyzer coupled with Fourier transforms infrared spectrometer (TG-FTIR) at the heating rate of 20 °C min−1. TG results illustrated that potassium decreased the peak temperature of carbohydrate pyrolysis, retarded the thermal degradation of the major components of RTS and meanwhile promoted the formation of stable char firmly depending on its chemical state. The organic potassium salts had a more significant effect on the process of char oxidation than inorganic ones with a new peak at around 570 °C. Analyses of evolved gaseous products distribution demonstrated a significant reduction of CO and CO2 during carbohydrates pyrolysis in the presence of potassium, especially organic potassium salts. Moreover, the maximum firecone temperature was also measured by Infrared thermography, and it had been found that the burning cone temperature of ED-modified RTS was averagely 13.27 °C higher than that of organic potassium treated RTS but averagely 16.57 °C lower than that of inorganic ones.

The thermal behavior and burning characteristics of reconstituted tobacco are closely interrelated with evolved gaseous products. The primary goal of this paper was to investigate the influence of urea phosphate (UP) on the pyrolysis behavior and subsequent gaseous products, especially carbon monoxide, resulting from pyrolysis and combustion of reconstituted tobacco. Characterization was performed using thermogravimetric analysis with measurement of products by means of Fourier transform infrared spectroscopy (TGA–FTIR) and flash pyrolysis–Fourier transform infrared spectroscopy (FPY–FTIR). Moreover, the influence of UP on CO delivery in mainstream smoke was also studied. TGA results illustrated UP accelerated thermal degradation of reconstituted tobacco and hindered the combustion of carbonized reconstituted tobacco. UP had a considerable influence on the evolution of gaseous products during thermal decomposition of reconstituted tobacco. What's more important, both CO delivery per cigarette and that per puff in the smoking process were significantly reduced depending on UP content in reconstituted tobacco. Comparative analysis of CO evolution patterns in the flash and slow pyrolysis elucidated that the heat rate was one of the most important factors in decreasing CO evolution by UP. These results demonstrated that UP was a potential burning additive controlling CO delivery in mainstream smoke of reconstituted tobacco.Highlights► The influence of urea phosphate on thermal behavior of reconstituted tobacco has been investigated for the first time. ► UP had a considerable influence on the evolution of gaseous products during thermal decomposition of reconstituted tobacco. ► Urea phosphate was evaluated for its performance of controlling CO delivery in mainstream smoke of reconstituted tobacco. ► The heat rate was one of the most important factors in decreasing CO evolution by urea phosphate.