Nano-ZnO/ nitrogen self-doped hierarchically porous graphite-like carbon derived from Astragalus residue toward effective removal of phenol

Background

Preparing porous carbon with rich pore structure and heteroatom doping is still the key issue for developing and utilizing biomass-based carbon materials.

Methods

Nano-ZnO/nitrogen self-doped hierarchically porous graphite-like carbon (AZC-700) was prepared from Astragalus residue by pyrolysis and used to adsorb phenol.

Significant Findings

AZC-700 showed a specific surface area of 1149 m² g⁻¹, hierarchical micro-/mesoporous structure, and adsorption capacity of 163.36 mg g⁻¹ on phenol, which was better than those of reported biochar. AZC-700 could remove 90.09 % phenol with low initial concentration (5 mg L⁻¹) in spiked Nanhu water to reach discharge standard, and it could maintain 89 % of the initial adsorption capacity after five cycles. ZnO nanoparticles anchored on AZC-700 as the spacer inhibited the stack of graphite-like. Self-doped nitrogen adsorbed phenol via π-π EDA, Lewis acid-base, hydrogen bond, and complexation. This study not only effectively utilized Astragalus residue, but also provided an efficient adsorbent for removing phenol.