Exploring the Efficacy of Hierarchical Porous Biochar in CO2 Capture and VOC Adsorption

Research shows lignin-based biochar produced via negative pressure pyrolysis optimizes CO2 and VOC adsorption due to its hierarchical porous structure. With significant SSA and micropore volume, it demonstrates high adsorption capacities and stability, proving effective for environmental remediation with excellent reusability.

April 18, 2024

1–2 minutes

Pan, et al (2024) Lignin-based hierarchical porous 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 prepared from negative pressure 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 enhanced CO₂and VOCs adsorption. *Separation and Purification Technology.* https://doi.org/10.1016/j.seppur.2024.127398

Recent research has highlighted the potential of hierarchical porous biochar prepared via negative pressure pyrolysis for effective CO2 capture and volatile organic compounds (VOCs) adsorption. This study, utilizing lignin-based biochar produced under different pressures (−0.1 MPa, 0 MPa, and 0.1 MPa), demonstrates significant advancements in biochar applications for environmental purification.

The biochar produced under a vacuum (−0.1 MPa) exhibited superior qualities with the highest specific surface area (SSA) recorded at 1577.48 m²/g and a micropore volume of 0.695 cm³/g, after acid washing which assisted in ashAsh is the non-combustible inorganic residue that remains after organic matter, like wood or biomass, is completely burned. It consists mainly of minerals and is different from biochar, which is produced through incomplete combustion. Ash Ash is the residue that remains after the complete More removal and minimized the average pore size to 1.81 nm. These characteristics contribute directly to its impressive CO2 adsorption capacity of 159.42 mg/g and benzene adsorption capacity of 470.03 mg/g, showcasing the material’s efficiency in trapping these pollutants.

Analytical models such as the Avrami and Freundlich models were applied to understand the adsorption processes, indicating that CO2 capture predominantly involves multilayer physical adsorption. The research confirmed a linear correlation between the biochar’s pore structure parameters and its adsorption capabilities, emphasizing the critical role of specific surface area and micropore volume in enhancing its performance.

Furthermore, the study explored the reusability of biochar, a vital factor for practical applications, revealing high stability with 83.9% to 98.7% retention in CO2 capture and 97.5% to 98.7% in benzene adsorption effectiveness after 10 cycles. These findings suggest that negative pressure pyrolysis not only optimizes the structural attributes of biochar but also enhances its functional reliability and sustainability.

In conclusion, the production of lignin-based biochar under negative pressure offers a promising solution to the growing environmental issue of atmospheric pollutants through enhanced adsorption capacities. This methodological approach paves the way for future innovations in biochar technology, potentially setting new standards for environmental remediation techniques.