By separating and modifying biochar’s naturally heterogeneous components—particularly sedimented particles (SP)—the researchers achieved much higher CO₂ adsorption capacity compared with untreated material. Alkali modification and controlled pyrolysis conditions further strengthened adsorption behavior, enabling the CO₂-saturated biochar to accelerate internal carbonation and densify cement microstructures.
Cement production accounts for nearly 8% of global CO₂ emissions, creating urgent demand for innovative mitigation strategies. Conventional carbon-capture approaches often face economic and efficiency barriers when applied at industrial scale. Biochar, produced through pyrolysis of biomass, is increasingly recognized for its stable structure, high specific surface area, and porous microarchitecture that facilitate CO₂ adsorption. Previous studies show that adsorption is influenced by feedstock, pore size, alkalinity, and pyrolysis temperature. However, most work has treated biochar as a uniform material, overlooking its internal heterogeneity. Moreover, the CO₂ adsorption potential of individual biochar components—and their performance once embedded in cement—remains poorly understood. Due to these limitations, deeper investigation into biochar’s structural behavior and CO₂-sequestering performance is urgently needed.
A study (DOI:10.48130/bchax-0025-0004) published in Biochar X on 20 October 2025 by Binglin Guo’s team, Hefei University of Technology, offer a promising pathway toward low-carbon construction materials by integrating carbon-sequestering additives directly into cement, one of the world’s highest-emission industrial products.
In this study, the researchers combined nitrogen adsorption (BET) analysis, FTIR spectroscopy, XRD, Raman spectroscopy, CO₂ adsorption tests with kinetic modeling, isothermal calorimetry, mechanical strength testing, SEM imaging, TG–DTG thermal analysis, and life-cycle–style emission accounting to systematically evaluate how alkali modification, pyrolysis temperature, and heterogeneous components of biochar affect its CO₂ adsorption behavior and the performance of biochar–cement composites. BET measurements showed that alkali treatment reduced the overall specific surface area but refined the microporous structure by corroding meso- and macropores, providing more favorable sites for CO₂ uptake. FTIR spectra revealed that alkali modification removed soluble organics such as phenols and diminished non-conjugated C=O, phenolic and aromatic bands at low pyrolysis temperatures, while enhancing –OH and ester-related vibrations, with weaker effects at higher temperatures. XRD patterns confirmed surface erosion and more pronounced SiO₂ peaks at higher pyrolysis temperatures, with SP less affected by alkali due to its altered structure. Raman spectroscopy indicated increasing structural disorder (higher ID/IG) with rising pyrolysis temperature and subtle differences between SP and bulk biochar, which, together with microporosity and alkalinity, influenced CO₂ uptake. CO₂ adsorption experiments showed that SP adsorbed more CO₂ than original biochar, and alkali-modified samples—especially MBC500—performed best; kinetic fitting favored the Avrami model and indicated fast, predominantly physical but partly chemical adsorption. Calorimetry, XRD/FTIR/SEM, and strength tests demonstrated that low–moderate biochar dosages enhanced hydration, carbonation, and microstructural densification, raising compressive strength, whereas excessive dosages increased porosity and reduced performance. TG–DTG and emission accounting further showed that CO₂ adsorbed on biochar accelerates calcite formation and that using SP in cement achieves net carbon reduction while also avoiding emissions from biomass disposal and fossil fuel use.
This research provides a practical approach for integrating carbon-capturing materials directly into cement formulations. The enhanced CO₂ adsorption capacity of modified SP can improve both the environmental footprint and mechanical performance of concrete, supporting broader decarbonization strategies in the construction industry. By using agricultural residues such as corn straw, the method promotes circular-economy practices and reduces the need for landfilling biomass waste. The findings also point to the importance of tailoring biochar microstructure and modification methods for maximal performance, offering a scalable pathway toward greener building materials.
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References
DOI
10.48130/bchax-0025-0004
Original Source URL
https://doi.org/10.48130/bchax-0025-0004
Funding information
This work was provided to BG by 'the Fundamental Research Funds for the Central Universities' (Grant No. PA20255GDGP0027), and 'the University Synergy Innovation Program of Anhui Province' (Grant No. GXXT–2023–104).
About Biochar X
Biochar X is an open access, online-only journal aims to transcend traditional disciplinary boundaries by providing a multidisciplinary platform for the exchange of cutting-edge research in both fundamental and applied aspects of biochar. The journal is dedicated to supporting the global biochar research community by offering an innovative, efficient, and professional outlet for sharing new findings and perspectives. Its core focus lies in the discovery of novel insights and the development of emerging applications in the rapidly growing field of biochar science.