Agricultural waste reduction was significant for the novel pathways of "waste control by control" and "synergize the reduction of pollution and carbon emissions". This study explores the utilization of crop waste through the preparation of sawdust biochar (SBC) via high-temperature pyrolysis for the adsorption removal of the neonicotinoid insecticide nitenpyram (NTP). A comprehensive characterization of SBC's physicochemical properties was conducted using various techniques such as scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction, Brunauer-Emmett-Teller analysis, Fourier-transform infrared spectroscopy, thermogravimetric analysis, Raman spectroscopy, zeta potential analysis, and X-ray photoelectron spectroscopy. The sample subjected to pyrolysis at 900 degrees C with a particle size range of 75-150 mu m (BC900M) exhibited an organized porous structure with a high specific surface area of 682.7 m(2)/g and an abundance of surface active groups and oxygen-containing functional groups. At optimal conditions (NTP concentration = 150 mg/L and BC900M dosage = 0.3 g/L), BC900M demonstrated a notable adsorption capacity of 115 mg/g. The NTP adsorption behavior aligned with the Langmuir and Freundlich isotherm models (R-2 > 0.96), the pseudo-second-order kinetics model, Delta H = 40.04 kJ<middle dot>mol(-1) and Delta S = 0.219 kJ<middle dot>K-1<middle dot>mol(-1), indicating a spontaneous and endothermic physical process involving both monolayer and multimolecular adsorption. The mechanisms encompassed micropore trapping, hydrogen-bond interactions, electrostatic attraction, pi-pi interactions, halogen bonding, and coordination interaction. Furthermore, a positive correlation between the adsorption performance of biochar and the pyrolysis temperature was observed, which was attributed to the decreased degree of graphitization of SBC based on the I-D/I-G ratios of BC300, BC500, BC700, and BC900 of 0.96, 1.01, 1.06, and 1.11, respectively. The adsorption free energy between NTP and SBC was -8.05, -8.31, -8.61, and -9.23 eV for BC300, BC500, BC700, and BC900, respectively. Those findings provide important insights for the efficient utilization of biomass resources for organic pollutant removal via high-performing adsorbents.
