CO2-mediated catalytic pyrolysis of cigarette filters over Co/SiO2

Improper disposal of cigarette butts (CBs) has posed a hazardous risk due to inevitable releases of toxic chemicals and microplastics into our ecosystem. As a precautious measure, this study carried out to develop an eco-friendly disposal platform for CBs. As such, cigarette filter (CF) and E-cigarette filter (ECF) were thermally degraded (pyrolyzed) using greenhouse gas (CO2) as a co-feedstock. Before pyrolysis studies, a hazardous potential of CF and ECF was qualitatively and quantitatively assessed. From the pyrolysis tests, it was observed that toxic chemicals in CF and ECF were thermally degraded/transformed into the non-toxic pyrogenic products. The enhanced thermolyses of CF and ECF were further realized in the presence of CO2. Catalytic pyrolyses over Co/ SiO2 were also done to further promote their thermal decomposition. The enhanced mechanistic functionality of CO2 imparted by the catalytic capability of Co/SiO2 directly led to additional syngas formation (up to 50 %). The beneficial features were originated from the homogeneous reactions of CO2 and volatile toxic chemicals stemming from CF and ECF over Co catalyst. Thus, all findings in this work highlighted that the CO2-supported catalytic pyrolysis could be a reliable/practical disposal platform for CBs.