One-step ball milling synthesis of functionalized carbon for enhanced toluene removal

A facile one-step ball milling strategy was developed for direct synthesis of functionalized carbon adsorbents from natural flake graphite. The obtained ball-milled carbon materials (FG-BM) were systematically characterized and evaluated for their enhanced toluene removal performance. The obtained FG-BM exhibited a transformed morphology from stacked layers to micron-sized spherical particles with hierarchical porosity, a dramatically increased specific surface area, and abundant nitrogen/oxygen functional groups. These structural and chemical modifications significantly enhanced toluene removal performance, achieving 99.75% efficiency compared to 67% for pristine FG, with complete mineralization of toluene into non-toxic CO 2 rather than CO. Systematic optimization revealed that milling parameters, including particularly ball size, rotational speed, and cycle number, critically influenced performance, with 15 mm balls, 700 rpm, and 8 cycles delivering optimal results. The strategy demonstrated high generality, notably improving toluene removal efficiency for three commercial carbon adsorbents from 25 to 35% to 90.6–99.8%. Mechanistic studies identified pyridinic-N and oxygen-containing groups (C O, O-C=O) as key active sites, facilitating toluene adsorption and catalytic oxidation via intermediates such as benzaldehyde and benzoic acid. This work provides a scalable, solvent-free route to high-performance functionalized carbon adsorbents for efficient toluene removal.