Advanced oxidation pretreatment of biomass for preparation of carbon-based adsorbents with high CO2 capture performance

The FeSO 4 ·7H 2 O/K 2 S 2 O 8 advanced oxidation system was adopted to prepare biochar-based CO 2 adsorbents. • The as-prepared adsorbent exhibited a high specific surface area of 1909.9 m 2 /g and a micropore ratio of 91.8 %. • The optimized adsorbent achieved a dynamic CO 2 adsorption capacity of 166.2 mg/g at 0 °C and 1 bar. • Advanced oxidation cut activator dosage and synergistically optimized microporous structure and surface chemistry. The advanced oxidation system composed of FeSO 4 ·7H 2 O/K 2 S 2 O 8 was adopted to pretreat pear tree branches, before carbonization and KOH activation, successfully producing porous carbon materials with excellent CO 2 adsorption performance. The sulfate radicals ( S O 4 - ∙ ) produced in the pretreatment process were capable of effectively breaking the chemical bonds between cellulose, hemicellulose, and lignin, leading to a decrease in the degree of polymerization. Concurrently, they convert the raw biomass into a loose, rough, lamellar architecture, accompanied with abundant oxygenic functional groups introduced. Dynamic adsorption tests confirmed the superior performance of ZBH@0.10, which delivered a CO 2 uptake of 166.1 mg/g at 0 °C, 124.8 mg/g at 25 °C and 98.3 mg/g at 45 °C under 0.1 MPa; static adsorption further revealed a CO 2 adsorption of 202.44 mg/g (25 °C, single–component isotherm) and a favorable CO 2 /N 2 selectivity of 30.24. After 10 regeneration cycles, the material maintained 98.7 % of its initial adsorption capacity, demonstrating excellent cycling stability. Mechanistic analysis indicated that physical adsorption played a primary role in the uptake process, with pore filling playing a key role. The pretreatment strategy significantly reduced the amount of activator required, while achieving synergistic optimization of the microporous structure and surface chemical properties and also markedly enhanced the CO 2 adsorption performance of the resulting adsorbent. This approach provided a new route for the resource utilization of agricultural and forestry wastes, as well as technological foundation for the design of low-cost, high-capacity biochar-based CO 2 sorbents.