Effects of Hardwood Biomass Variability on Biochar Properties: Insights from Wood Waste Utilization

Wood is an abundant and renewable resource with considerable potential for upcycling into high-value products such as biochar, thereby facilitating the conversion of waste into useful materials. The structural and compositional diversity among wood species significantly influences the properties of the resulting biochar. This study aimed to investigate the properties of biochar derived from five distinct hardwood species, all sourced from the same tropical region and produced under standardized pyrolysis conditions using a patented furnace. The hardwood species examined were Leucaena (Leucaena leucocephala (Lamk.) de Wit.), paper flower climber (Getonia floribunda (Roxb.) Lam.), rain tree (Samanea saman (Jacq.) Merr.), climbing wattle (Albizia myriophylla Benth.), and Siamese blachia (Blachia siamensisGagnep.). The investigation focused on fundamental properties of the biochar, including morphology, elemental composition (C, H, N, O), water-holding capacity, aromaticity (H/C ratio), polarity (O/C and (O+N)/C ratios), and the C/N ratio. Results indicated that all five biochar types were of high quality, with carbon contents ranging from 66.64% to 84.76%, a high degree of aromaticity (H/C < 0.7), low polarity, and enhanced stability. The biochars exhibited a range of pore structures from macropores to mesopores, with pore volumes of 0.010–0.074 cm³/g and specific surface areas ranging from 2.92 m²/g to 144.59 m²/g. These structural attributes influence their water-holding capacities; however, the relationships among polarity, pore volume, pore size, and water-holding capacity remain unresolved. The findings highlighted substantial variability in the properties and morphology of the biochars, despite their production under identical conditions. This variability underscores the need for further in-depth studies to elucidate the factors governing biochar properties and to enable the tailoring of biochar for specific applications. Doi: 10.28991/HEF-2025-06-01-02 Full Text: PDF