Developing efficient biochar (BC) adsorbent for pollution removal has been a long-term exploration. However, the negative charge surface of pristine BC seriously impedes the transfer of anionic dye through the pore of BC and results in low adsorption capacity. Herein, N-doping enriched porous MgO-modified biochar (MBC) was successfully prepared through a facile nitrate activation method for anionic acid fuchsin (AF) removal. The Ndoped group of secondary amine in MBC changes the surface charge of BC and facilitate the AF adsorption onto MgO. The as-prepared MBC exhibited superior adsorption capacity of 328 mg center dot g(-1). The adsorption process was well aligned with the Freundlich and pseudo-second-order kinetics models indicating a hybrid physicochemical adsorption mechanism. Further mechanism investigation indicates that N-doped group, MgO and functional groups in biochar matrix primarily contribute to AF adsorption. The mechanism includes: electrostatic attraction, pi-pi interaction, hydrogen bonding and pore filling. This research provides an environmentally friendly nitrate activation strategy for BC, which overcomes the inherent defects of BC in negative charge surface and provides a facile way of biomass valorization for pollution removal from the aquatic environment.
