Thermochemical conversion of comingled food waste to bio-oil through microwave copyrolysis using different�susceptors

Abstract

Microwave (MW)-induced copyrolysis of food waste (FW) and low-density polyethylene (LDPE) using different MW susceptors were explored in the present study. The effects of different MW susceptors (granular activated carbon (GAC), flyash, silica gel, and cement) on bio-oil yield and quality were investigated. Compared to other MW susceptors, silica gel gave the highest bio-oil yield (50 wt.%), whereas the lowest total acid number (TAN) (14.16�mg KOH/g), oxygenated compounds (13.28 wt.%), high higher heating value (HHV) (23891�kJ/kg), and maximum energy yield (73%) in bio-oil were obtained with cement. An inverse relationship was observed between the heating rate of feedstock and the percentage of acids and ketones in bio-oil, which was due to the long residence time for volatiles inside the MW reactor and the reaction of the water molecule with aromatic hydrocarbons. Comparison of bio-oil properties with various biodiesel standards (ASTM D 6751, EN 14214:2012, and IS 15607:2016) indicated the need of upgradation to meet the standard values. Overall, this study exhibited the suitability of MW susceptors on MW copyrolysis of domestic FW and LDPE to achieve significant quantity and quality of bio-oil. Further upgradation of bio-oil obtained from this study is highly recommended to meet the abovementioned standards. � 2022, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.