Physicochemical and thermal characterization of argan residues for biofuel and biochar production: potential future prospects

The recovery of biomass waste by conversion to biochar or biofuel is an efficient and environmentally friendly method of biomass valorisation. This paper compares for the first time the physicochemical, structural, thermal, and energetic properties of three types of argan residues: black argan press cake (BAC), white argan press cake (WAC), and pellet argan cake (PAC) for their potential use as biofuel or biochar. The study showed that the three residues have a high content of carbon (52-61%), volatile matter (86-91%), and calorific value (higher- and lower-heating value 24-27 MJ/kg and 23-25 MJ/kg, respectively), and a low content of ash (3.3-4.2%) and moisture (1.5-3.3%), confirming their suitability as efficient sources for the production of fuel and biochar. The calorific value and combustion rate of argan residues were higher compared to other residues reported in the literature, thus underlining the potential utility of these biomasses as biofuels. In addition, the thermal analysis showed that the three biomasses exhibit a reactive behaviour during the pyrolysis processes, which ends at about 450 degrees C, suggesting their possibility of converting into biochar at relatively low temperatures. Overall, the results obtained suggest WAC as the best compromise in terms of energetic properties and attributes prone to generate a valuable sorption material to be used in wastewater treatment. Thus, WAC could be a credible alternative to conventional fuels and offering new perspectives for its use as an optimal bioresource for biochar and biofuel production.