One-pot synthesis of metallic cobalt nanoparticle-embedded biochar from Dipterocarpus alatus leaves for percarbonate-mediated degradation of acid orange 7

Fallen Dipterocarpus alatus leaves (DALs) are commonly considered urban waste without any use. In this study, this biomass was used to synthesize zero-valent cobalt nanoparticle–embedded biochar (CoNPs/BC). One-pot pyrolysis of CoCl₂-impregnated DAL at 700°C within 1 h in a nitrogen atmosphere yielded metallic cobalt nanoparticles (CoNPs) with their average size of 30 ± 11 nm uniformly dispersed within the biochar (BC) matrix. Moreover, CoNPs/BC exhibited a high surface area (336 m²/g), a total pore volume (0.21 cm³/g), and strong saturation magnetization (7.9 emu/g). CoNPs/BC was accordingly explored for sodium percarbonate (SPC) activation to treat acid orange 7 (AO7). As a result, 0.200 g/L of CoNPs/BC effectively activated 5.00 mM of SPC to degrade 96.0–97.9% of AO7 (50 ppm) within 60 min under neutral conditions (pH 7.0–9.0). Scavenging experiments confirmed the simultaneous generation of multiple reactive oxygen species (¹O₂, CO₃ •− , O₂ •− , ·OH), sustained by Co(III)/Co(II) redox cycling. These findings emphasize the possible use of DAL-derived CoNPs/BC as an effective, magnetically separable catalyst for SPC-based advanced oxidation processes, offering a promising pathway for both biomass valorization and sustainable wastewater remediation.