Circular economy and multifunctional valorization of Dabéma (Piptadeniastrum africanum) sawdust for biorefinery applications and clean sustainable energy

The concept of the circular economy promotes the valorization of waste into high value-added products and sustainable energy alternatives. In this context, sawdust, a major by-product of the forestry industry, offers strong potential both for the extraction of bioactive compounds and for the production of solid biofuels. This study combined biorefinery and energy techniques to valorize Dabéma sawdust by isolating bioactive compounds and producing fuel briquettes. The total polyphenol content of the extracts ranged from 0.005 ± 0.001 (gGAE/100gDM) to 0.148 ± 0.019 (gGAE/100gDM) for macerated and infused extracts, respectively. The total flavonoid content ranged from 0.004 ± 0.001 (gCE/100gDM) (maceration) to 0.009 ± 0.001 (infusion) (gCE/100gDM). The tannin content ranged from 0.006 ± 0.002 (gTAE/100gDM) (maceration) and 0.006 ± 0.001 (infusion) (gTAE/100gDM). The extraction of secondary metabolites had no significant effect on the immediate and combustion properties of the briquettes ( p > 0.5); however, it influenced their energetic and mechanical properties ( p < 0.5). The Higher Heating Value ranged from 25,373 ± 263 kJ/kg to 26,424 ± 25.5 kJ/kg for samples with and without secondary metabolites, respectively. The Shatter Resistance Index ranged between 327.4 ± 25% (fuels without secondary metabolites) and 244.1 ± 29.2% (fuels with secondary metabolites). EDS and FTIR analyses confirmed that thermal treatment increases carbon content while reducing oxygen in the biomass. Given the natural durability of Dabéma wood (class D, highly resistant to termites), future research will focus on exploring the use of its extracts as potential agents to enhance the resistance of wood species and derived materials that are vulnerable to termite attacks.