Work

Effect of thermal treatment on the structure and CO2 adsorption capacity of biochar from chicken manure and onion peels

Year: 2026

Type: article

Abstract: This study investigates the thermal conversion of chicken manure and onion peels into biochars with tailored properties for CO 2 adsorption. The process was conducted at 700, 800 and 900 °C under inert atmosphere. The resulting biochars were characterised using Fourier-Transform Infrared Spectroscopy, X-Ray Diffraction (XRD), X-Ray Fluorescence (XRF), Scanning Electron Microscopy, X-ray Photoelectron Spectroscopy (XPS), Raman spectroscopy, nitrogen sorption analysis, and CO 2 adsorption measurements. Increasing pyrolysis temperature enhanced carbonisation, reduced heteroatom content, and promoted pore development, particularly in onion peels-derived in biochars. Nitrogen sorption analysis revealed the development of mesoporous and microporous structures, with the biochar derived from onion peels at 900 °C exhibiting the highest specific surface area (109.8 m 2 /g). However, the CO 2 adsorption capacity showed divergent trends: it correlated with surface area development in chicken manure biochars, whereas onion-peel-derived biochars showed a non-monotonic relationship, with the 700 °C sample having the highest adsorption capacity (26.6 cm 3 /g at 100 kPa). In contrast, chicken manure biochars exhibited increased CO 2 adsorption capacity with increasing pyrolysis temperature, which was associated with the development of micropores and the presence of calcium-rich mineral phases, identified by XRD and XRF analyses. Raman and XPS analyses indicated progressive structural ordering and deoxygenation with increasing pyrolysis temperature. The results demonstrate that CO 2 adsorption in biochars derived from onion peels is mainly governed by pore-filling mechanisms, while mineral-assisted interactions significantly contribute to CO 2 capture in chicken manure biochars.

Source: Clean Technologies and Environmental Policy

DOI: 10.1007/s10098-026-03598-2