CONICET | Buscador de Institutos y Recursos Humanos

Plastics have become a crucial part of lifestyle, and the global plastic production has increased extremely during the past decades. At end-of-life, products disposal generates huge amounts of postconsumer plastic wastes which require safe management to avoid potentially detrimental impacts on the environment. In particular, polyethylene terephthalate (PET) constitutes one of the major post-consumer plastics in solid waste streams because of the ongoing expansion of the PET bottle market. In the search of new routes for cost-effective solutions for plastics waste management, co-pyrolysis is perceived as an interesting technology for co-processing PET wastes with woody biomass in order to improve the quality and yield of liquid products for their use as fuels with respect to those produced from pyrolysis of the biomass individually. In this scenario, co-pyrolysis of equal proportions of PET bottle waste and poplar (Populus deltoide) wood sawdust, as representative biomass, is investigated. To obtain useful information for the reliable design and operation of conversion units, kinetic characterization of the co-pyrolysis and of the pyrolysis of the individual components is comparatively carried out by non-isothermal thermogravimetric analysis, from ambient temperature up to 600¡ãC, and modelling. The co-pyrolysis is characterized by an intermediate energy activation (~87 kJ mol-1) comprised between the values estimated for the pyrolysis of the individual wastes. Free radicals likely formed from wood sawdust pyrolysis at low temperatures (< 350¡ãC) should facilitate the degradation of the polymeric waste present in the mixture. On the other hand, the co-pyrolysis and the pyrolysis of the individual wastes are conducted in a bench-scale set-up at temperatures in the range 400¡ãC ¨C 600¡ãC, to obtain and characterize the solid products (chars). Char yield decreases with increasing temperature, mostly accompanied by reduction in volatile matter content and %O, and increases in ash and %C. At 500¡ãC and 600¡ãC, char yield for the co-pyrolysis attains intermediate values between those for the pyrolysis of the individal wastes, but it is lower at 400¡ãC pointing to synergistic effects. The higher %C of the chars derived from the co-pyrolysis at the two higher temperatures is reflected in enhanced calorific values (HHV¡Ö30-31 MJ kg-1) compared to those produced from the biomass pyrolysis individually, suggesting greater potentialities for their use as solid fuels. Different predictors based on chemical characteristics of the chars also indicate that they might be applied in soil for carbon sequestration, especially those generated at the higher temperatures. Furthermore, the char obtained from the co-pyrolysis at 500¡ãC shows a BET surface area of ~400 m2 g-1 and total pore volume of 0.22 cm3 g-1. Accordingly, it could be employed as soil improver and/or as adsorbent of average quality for the uptake of water contaminants.

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