Nitrogen doped sinocalamus oldhami lignin-based activated biochar with high specific surface area: Preparation and its adsorption for malachite green contaminant

A new nitrogen doped sinocalamus oldhami lignin-based activated biochar (denoted as N-BGAC) with a notably high adsorption efficiency was prepared for the removal of malachite green (MG). The properties and structure of N-BGAC were thoroughly characterized, alongside an investigation into the MG adsorption process. The findings revealed that N-BGAC possessed a substantial specific surface area of 2238 m(2) g(-1), nearly double that of the activated biochar lacking nitrogen doping (BGAC). Additionally, N-BGAC exhibited exceptional adsorption efficiency for MG, boasting a maximum adsorption capacity of 1372.5 mg g(-1), marking an enhancement of nearly 2.5 times compared to BGAC. By exploring the adsorption mechanism, it could be found that the adsorption process was a spontaneous exothermic reaction, and mainly controlled by pore-filling effect, electrostatic interactions, hydrogen bonding, hydrophobic interactions and pi-pi bonding interactions. Crucially, in the regeneration experiments, the removal percentage of MG could still reach 81.5% after four cycles of regeneration, making it promising in the contaminant removal.