Kim & Hadigheh (2024) Oxidative 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 for enhanced-CO₂adsorption capacity in biosolid-derived biocharBiochar is a carbon-rich material created from biomass decomposition in low-oxygen conditions. It has important applications in environmental remediation, soil improvement, agriculture, carbon sequestration, energy storage, and sustainable materials, promoting efficiency and reducing waste in various contexts while addressing climate change challenges. More. BiomassBiomass is a complex biological organic or non-organic solid product derived from living or recently living organism and available naturally. Various types of wastes such as animal manure, waste paper, sludge and many industrial wastes are also treated as biomass because like natural biomass these More & Bioenergy. https://doi.org/10.1016/j.biombioe.2024.107407

Biosolid-derived biochar is a promising material for carbon capture, produced through pyrolysis and oxidative pyrolysis. This study aimed to improve the CO2 adsorption capacity of biochar by using oxidative pyrolysis, a process that introduces oxygen into the reaction, resulting in biochar with enhanced properties. The researchers examined biochar produced at different temperatures and oxygen concentrations, focusing on its CO2 adsorption efficiency and durability over repeated cycles.

The study demonstrated that biochar produced from oxidative pyrolysis at 700°C with a low oxygen concentration (1.25%) had a higher CO2 adsorption capacity (7.5 mg/g) compared to conventional pyrolysis biochar. This improvement was attributed to better surface properties, such as increased microporosity and surface oxygenation. Furthermore, the adsorption process was dominated by physical adsorption (physisorption) as indicated by activation energies below 40 kJ/mol. The research also showed that film and intraparticle diffusion were the key mechanisms limiting the adsorption rate.

After five adsorption/desorption cycles, the biochar samples retained 84-85% of their initial adsorption capacity, proving their reusability. Although oxidative pyrolysis improves performance, the study noted that excessive oxygen levels could degrade the biochar’s structure. The findings suggest that oxidative pyrolysis offers a more energy-efficient method for producing biochar, offering a sustainable solution for CO2 capture with potential applications in carbon capture and storage (CCS) technologies.