Creating easily accessible adsorption sites in natural wood-derived hierarchical porous carbon via a controlled delignification strategy for organic pollutant removal

Hierarchical porous carbons (HPC) are effective in removing dyes and antibiotics from wastewater, but their production primarily relies on tedious, high-pollution, and costly template methods. Here, a facile and efficient two-step method was developed to prepare HPC from natural wood. The process involves alkaline pretreatment to form a porous and exposed natural structure, followed by CO₂ activation to create a hierarchical pore structure. The optimized HPC (B3-CO₂) achieved a high S_BET of 1484.5 m² g⁻¹ and a pore volume of 1.66 cm³ g⁻¹, with mesopores accounting for 79.52 % of the total pore volume. Then, the B3-CO₂ sample was applied for MB and TC adsorption, exhibiting excellent performance with adsorption capacities of 549.45 and 925.93 mg g⁻¹, respectively. Furthermore, this study employed DTG deconvolution techniques to analyze the structural evolutions in hemicellulose, cellulose, and lignin during the HPC production. Results revealed that cellulose composition had a strong positive correlation with HPC performance, including S_BET, pore volume, mesopore proportion, graphitization degree, and adsorption capacities. Conclusively, this work not only presents a simple and green approach for the preparation of high-performance HPC but also offers new perspectives for understanding the composition-structure-performance relationship from wood to HPC production.