Effective xylan integration for remodeling biochar uniformity and porosity to enhance chemical elimination and CO₂ adsorption

Although plant evolution has offered diverse biomass resources, the production of high-quality biochar from desirable lignocelluloses remains unexplored. In this study, distinct lignocellulose substrates derived from eight representative plant species were employed to prepare biochar samples under three different temperature treatments. Correlation analysis showed that only hemicellulose was a consistently positive factor of lignocellulose substrates to account for the dye-adsorption capacities of diverse biochar samples. Furthermore, we integrated exo-xylan, a major hemicellulose in higher plants, into lignin-disassociated lignocelluloses to produce the desirable biochar with a uniform and symmetrical structure, resulting in a 5.2-fold increase in surface area (51 to 317 m²/g) and a 5.0-fold increase in total pore volume (0.02 to 0.11 cm³/g micropore, 0.02 to 0.12 cm³/g mesopore). This consequently improved the adsorption capacities of the remodeled biochar, with an increase of 26 % for dual-industry dyes, 90 % for 1579 organic compounds, and 14 % for CO₂. Based on the fluorescence observation of xylan-cellulose co-localization and physical-chemical characterization of the remodeled biochar, a novel hypothetical model was proposed to explain how xylan plays an integral role in desired biochar production, providing insights into effective lignocellulose reconstruction and efficient thermochemical catalysis as an integrative strategy to maximize biochar adsorption capacity.