Opportunity for sustainable biomass valorization to produce biochar for improving soil characteristics

Biochar, a byproduct obtained from valorization of waste biomass, is utilized in environmental management to restore or improve soil functions where it alters chemical, physical, and biological processes. Therefore, in this study, vastly available oak sawdust was evaluated as a potential feedstock for biochar production with the aim to identify the influence of carbonization conditions on biochar characteristics. Slow pyrolysis with temperatures ranging from 400 to 600 °C and residence times from 15 to 120 min was performed. The feedstock material and resulting biochar were characterized for physical, chemical, and hydraulic properties that are significant for their ability and characteristics as a soil amendment. The pH, BET surface area, carbon content, nutrient content, alkaline functional groups, and water holding capacity increased with increasing pyrolysis temperature and residence time while biochar yield, O/C ratio, and acidic functional groups decreased. Although the effect of holding time on biochar physicochemical properties is less significant than that of temperature, it is an essential parameter to obtain desired biochar properties. It can be concluded that pyrolysis has the potential to add value to regionally available oak sawdust on a sustainable basis and help to restore or improve essential soil functions. Graphical abstract