Conversion of peach endocarp and polyethylene residue by the co-pyrolysis process

The south of Brazil has a high production of peaches which generates the stone as residue. The recycling of biomass and plastic waste is a challenge that must be overcome. Therefore, co-pyrolysis emerges as a possibility for joint conversion of peach stone and plastic bags into value-added products. Thus, the objective is to obtain new products, emphasizing the organic fraction of the bio-oil obtained under the best experimental conditions, and to characterize it by GC-MS. The experiments provided a three-phase bio-oil: two organic phases with different densities and an aqueous phase. It was observed that the central point experiment (temperature at 500 °C and blend composition, % peach stone/polyethylene, 80/20) generated the highest yield of bio-oil. However, the experiment at the lowest temperature and with greater addition of plastic waste produced a higher organic fraction. Using gas chromatography, 161 chemical compounds were identified in the denser organic phase, emphasizing the phenols. In the lighter organic fraction, hydrocarbons were the majority among the 70 compounds identified. The results suggest that the interaction between biomass and polyethylene influences the characteristics of the products obtained, since polyethylene acts as dispersant and as hydrogen donor. Co-pyrolysis, in this research, proves to be efficient and viable, allowing the joint destination of those environmental liabilities.