Waste eliminated by waste: industrial o-phenylenediamine residue derived N,O co-doped hierarchical porous carbon for efficient o-nitroaniline removal

Abstract

The flourishing fine chemical industry has concurrently precipitated dual environmental challenges in the form of wastewater and solid waste. In the present study, o-phenylenediamine distillation residue was employed as a raw material and a recyclable Mg(CH₃COO)₂ template pore-forming strategy was established to fabricate a series of in situ N/O co-doped porous carbons. The as-prepared porous carbons were utilized for the efficient adsorptive removal of o-nitroaniline (ONA) from aqueous solutions. By benchmarking against K₂CO₃-activated porous carbon, the structure–activity relationship between the pore structure and ONA adsorption capacity was systematically evaluated. The optimized carbon sample (AWC-M-1) exhibiting a high specific surface area of 1209.21 m² g⁻¹ and a hierarchical pore structure demonstrated a remarkable ONA adsorption capacity of 639.9 mg g⁻¹ and outstanding continuous fixed-bed adsorption–regeneration performance. Furthermore, the AWC-M-1 exhibits excellent tolerance for ONA adsorption under various ionic backgrounds and real water matrix conditions. The combined physicochemical characterization, adsorption equilibrium, kinetic study and DFT calculations reveal the adsorption performance and mechanism of ONA enhanced by the mesopore-dominated hierarchical pore structure and surface functionalization with N,O co-doped species.