This study investigated the impact of carbon dioxide (CO2) as a carrier gas on biochar characteristics during pyrolysisPyrolysis is a thermochemical process that converts waste biomass into bio-char, bio-oil, and pyro-gas. It offers significant advantages in waste valorization, turning low-value materials into economically valuable resources. Its versatility allows for tailored products based on operational conditions, presenting itself as a cost-effective and efficient More, introducing a novel calculation and comparison method. Surprisingly, pyrolysis temperature held greater sway over biochar properties than residence timeResidence time refers to the duration that the biomass is heated during the pyrolysis process. The residence time can influence the properties of the biochar produced.   More. Notably, CO2 significantly reduced dissolved organic carbon (DOC) content in biochar, reaching 81.6% reduction at 700°C compared to nitrogen atmosphere. Furthermore, CO2 lowered total heavy metal content while affecting soluble microbial by-products and humic acid-like substances more noticeably. Interestingly, tryptophan-containing protein-like substances, linked to copper binding, exhibited higher susceptibility to CO2 pyrolysis.

Using FactSage thermodynamic simulation and analyzing syngasSyngas, or synthesis gas, is a fuel gas mixture consisting primarily of hydrogen and carbon monoxide. It is produced during gasification and can be used as a fuel source or as a feedstock for producing other chemicals and fuels.   More composition, the study pinpointed CO2’s influence on carbonaceous distribution through dehydrogenation, methane production, and the Boudouard reaction. This resulted in a significant increase in carbon monoxide proportion within syngas (18.5% at 700°C).

These findings pave the way for further CO2 utilization as a raw material in biochar production, enhancing the feasibility of applying sewage sludge biochar to farmland soil. This not only promotes sustainable waste management but also holds promise for improving soil quality and agricultural productivity.