Facile preparation of alveolate biochar derived from seaweed biomass with potential removal performance for cationic dye

• An innovative nitrogen self-doped alveolate biochar was successfully prepared. • Samples possessed outstanding characteristics, such as OH, C O and CONH . • AKB-600 represented with the specific surface area up to 1738 m 2 /g. • Up to 94.61 % removal efficiency of dye was achieved during reaction system. • Nitrogen-containing and conjugated structures facilitated the actual adsorption. Novel N-doped biochar (AKB) nanomaterials derived from raw kelp root were successfully developed at different temperatures (600–1000 °C) and were used to explore the adsorption performance of cationic dye from water. Various characterization technologies including scanning electron microscopy (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD) patterns, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) spectroscopy and Raman spectroscopy were used to analyze the physical and chemical properties of the samples. The porosity analysis demonstrated that AKB carbonized at 600 °C (AKB-600) possessed a higher specific surface area (1738 m 2 /g) with a honeycomb-like microstructure. Meanwhile, AKB exhibited abundant functional groups on its surface, such as OH, C O and CONH from FT-IR and XPS analysis, resulting to the high removal efficiency of dye, up to 94.61 % at 60 min. The adsorption isotherm and kinetics data were more suitable for the Langmuir model and the Pseudo-second-order model. Electrostatic interactions and physical adsorption played dominant roles in the adsorption process, particularly, the nitrogen-containing and conjugated structures also facilitated the actual adsorption. Hence, AKB has enormous practical application potential acting as a high-effective adsorbent in the field of dye wastewater treatment.