Nitrogen-doped activated carbons derived from biomass and waste have attracted increasing attention due to their strong potential for environmental remediation applications. Herein, nitrogen-doped activated carbons (NACs) were synthesized using waste medium-density fiberboard (MDF) as a carbon source and blood meal (BM) as a nitrogen-rich source through the simultaneous process of chemical activation and N-doping. The adsorption performance of the newly synthesized NACs was assessed to remove methyl orange (MO) and methylene blue (MB) dyes. The adsorption study showed that incorporating BM into activated carbon derived from MDF waste significantly enhanced its adsorption behavior toward MB and MO. Characterization analysis confirms that nitrogen was successfully incorporated into the activated carbon structure. The results of BET analysis showed that NACs have a larger specific surface area (SBET), ranging from 1511 to 2030 m2.g−1, compared to MDF-derived AC (1252 m2.g−1). CHN analysis indicated that nitrogen content increased from 0.75 wt% in MDF-derived AC to 3.51 wt% in NAC (1:2). The dye adsorption kinetics followed a pseudo-second-order model, whereas the Langmuir model effectively described the adsorption isotherms. Moreover, thermodynamic studies revealed that the adsorption occurs spontaneously and is endothermic. Finally, NAC (1:2) demonstrated the maximum adsorption capacity of 527.27 and 467.71 mg.g−1 for MB and MO, respectively. This study showed that the use of blood meal as a low-cost and readily available nitrogen-rich waste source effectively improved the adsorption potential of non-doped MDF-derived activated carbon for treating wastewater containing cationic and anionic dye pollutants.

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