Boron-doped activated carbon derived from Zoysia sinica for Rhodamine B adsorption: The crucial roles of defect structures

[Display omitted] •Zoysia sinica was converted to boron-doped carbon (ACB2) by chemical impregnation and 900 °C calcination.•ACB2 efficiently removed RhB with the maximum adsorption capacity of 1337.2 mg/g under unadjusted pH at the temperature of 298 K.•The introduction of boron can modulate the electron density of the ACB2 surface.•Boron species as Lewis acid sites promote a high affinity of RhB to the ACB2 surface.•The defect structure and oxygen-containing functional groups of ACB2 collectively promote the removal of RhB. A boron-doped porous activated carbon was prepared using Zoysia sinica as the carbon source, boric acid as the doping agent, and sodium hydroxide as the activator. The morphology and structure analysis manifested that the optimized boron-doped porous activated carbon (denoted as ACB2) possessed a layered pore structure and a high specific surface area (951.0 m2/g). Compared with the pristine activated carbon (AC), the introduction of boron gave birth to adjust the electron density on the carbon surface, and resulting the electronic interactions strengthened the binding between the adsorbent and Rhodamine B (RhB), meanwhile, Lewis acid sites also were introduced and promoted a high affinity of RhB to the adsorbent surface. In addition, the kinetic and equilibrium data for the RhB adsorption onto ACB2 fitted well for the pseudo-second-order model and the Langmuir isotherm model, representing chemical and monolayer adsorption, respectively. Encouragingly, the boron-doped activated carbon exhibited excellent pH adaptability, with a maximum theoretical adsorption capacity of 1337.2 mg/g at unadjusted pH (298 K). In general, the boron-doped porous activated carbon is efficient for RhB removal and this work is also to give a state of developing heteroatom boron doping of activated carbon from cheap biomass with high-performance for dye removal.