Thermochemical Behavior of Tris(2-Butoxyethyl) Phosphate (TBEP) during Co-pyrolysis with Biomass

Co-pyrolysis of plastic waste and wood biomass to recover valuable chemicals is a cost-effective waste-recycling technology. However, widely used organophosphate ester additives in plastic, such as tris(2-butoxyethyl) phosphate (TBEP), can form diverse phosphorus (P)-containing species. These P-containing compounds can pose new environmental challenges when the biochar is reused. In this study, a mixture of TBEP and lignin was used to simulate the feedstock of plastic waste and wood biomass, and the thermochemical behavior of TBEP in slow pyrolysis (20 K min–1) and fast pyrolysis at 400–600 °C was investigated. The results show that low temperature in fast pyrolysis favors the enrichment of P in char. Up to 76.6% of initial P in the feedstock is retained in the char resulting from 400 °C, while only 51% is retained in the char from 600 °C. Slow pyrolysis favors the formation of stable P species regardless of the temperature; only 7% of the P retained in the char is extractable from char from slow pyrolysi...