Thermo-chemical processes for the sustainable utilization of oil-bearing biomass: A case study on apricot seed valorization

Abstract

This study investigated the thermochemical processing of defatted residue to achieve zero-waste utilization of oil-bearing biomass using apricot seed as the model compound. Defatted apricot seeds (DAS) obtained after oil extraction from apricot seed were valorized through pyrolysis platform, focusing on enhancing sustainability using CO2 as the reaction medium. The results showed that CO2 plays a crucial role in the pyrolysis process, leading to an enhanced CO formation through homogeneous reaction between CO2 and volatile matters stemming from DAS. Specifically, CO2 oxidized volatile matters while simultaneously reducing to CO and influenced the morphological properties of DAS biochars (DASBs), leading the development of pores with sizes of less than 16 nm and exceeding 50 nm. The larger pore size of DASBs fabricated under N2 and CO2, compared to 2 nm (the molecular size of triglycerides), makes them suitable as porous materials for thermally induced transesterification. The presence of alkaline metals in DASBs expedited thermally induced transesterification. At ≤ 330 °C, DASB fabricated under CO2 condition exhibited faster reaction kinetics than under N2 condition. This suggests that the use of CO2 in the fabrication of DASB results in favorable surface properties conducive to the thermally induced transesterification of apricot oil.