The effect of co-pyrolysis of bamboo waste and polypropylene on biomass deoxygenation and carbonization processes

While numerous research studies have delved into the co-pyrolysis of biomass and plastic waste, limited attention has been devoted to comprehending the interaction mechanism that impacts biomass deoxygenation and carbonization. Therefore, this study explores the co-effect of temperature and polypropylene blending ratio on co-pyrolysis reaction kinetics, distribution of oxygenates/hydrocarbons, as well as the evolution of biochar structure. At a blending ratio of 0.5, the co-pyrolysis exhibits the lowest activation energy (146 kJ/mol), approximately 25.1 % lower than that required for individual pyrolysis. The interaction between bamboo waste with polypropylene increases the O-abstraction process, resulting in the creation of O-containing free radicals and hydrocarbon compounds. The peak proportion of aromatic compounds, reaching approximately 69.5 %, is observed at 700 °C when the blending ratio is 0.5. The H-abstraction process converts large-molecular alkanes into H free radicals and tiny-molecular unsaturated hydrocarbons. The aliphatic functional group content diminishes as the polypropylene ratio increases. The maximum specific surface area (7.70 m2/g) and pore volume (21.7 mm3/g) are achieved at a blending ratio of 0.75. Notably, polypropylene exerts minimal influence on the graphite crystallite size and graphitization degree of biochar. This research significantly contributes to advancing our understanding of the interaction mechanisms between biomass and plastic waste.