Pyrolysis of cigarette paper: effects of metal salts on pore formation and carbon monoxide release in mainstream smoke

To investigate the effects of selected metal salts (potassium citrate, calcium acetate, zinc acetate, calcium chloride and zinc chloride) on the pyrolysis behavior of cigarette paper, the release of carbon monoxide in mainstream smoke and the temperature distribution of burning cigarette cone, the pyrolysis behavior of cigarette paper was studied by a combination of thermogravimetry analysis (TGA), mercury porosimetry of cigarette paper, scanning electron microscopy (SEM), and bespoke thermocouple array technique. The results indicated that:1) Adding different metal salts into cigarette paper influenced the level of carbon monoxide in mainstream smoke differently; potassium citrate promoted the pore formation during the pyrolysis of fiber in cigarette paper, which increased the pore volume and micropore amount in the vicinity of char line, and the synergistic action of outward diffusion and dilution significantly decreased the CO release in mainstream smoke. However, the effects of zinc acetate, calcium acetate, calcium chloride and zinc chloride were opposite. 2) Comparing with the control (cigarette paper without adding metal salts), adding potassium citrate into cigarette paper reduced the volume of burning cone of cigarette at high temperature (above 750℃). On the contrary, adding zinc acetate, calcium acetate, calcium chloride and zinc chloride had an opposite effect on the high temperature region. Therefore, the addition of metal salts into cigarette paper significantly affected the volume of burning cone of cigarette and the release of CO in mainstream smoke. The smaller volume of burning cone at high temperature showed the less CO level in mainstream smoke.