Synthesis of a novel nitrogen-doped biochar co-immobilized enzymes for xylan hydrolysis

The corncob residue after extraction xylan was modified by the nitrogen doping method to prepare a novel nitrogen-doped biochar carrier. The nitrogen-doped biochar carrier termed NBC-121 was synthesized through meticulous adjustment of the NaHCO₃ to melamine ratio. The structure of nitrogen-doped biochar was characterized by Scanning electron microscopy (SEM), Ultraviolet-visible diffuse reflectance spectroscopy (UV/Vis DRS), Fourier transform infrared spectroscopy (FTIR), Specific surface area analyzer, X-ray photoelectron spectroscopy, and X-ray diffractometer. It was demonstrated that NBC-121 was a suitable carrier with rich polar functional groups, developed pores, increased surface nitrogen, and promoted electron transfer. The immobilized multi-enzymes were further prepared by using NBC-121 as a carrier. The distribution and conformation of the immobilized enzymes were analyzed by SEM, FTIR, fluorescence microscopy and fluorescence spectroscopy. The hemicellulase and xylanase were effectively immobilized due to the abundant pores and functional groups on the surface of carrier. The multi-enzymes immobilized on the NBC-121 exhibited excellent stability in terms of thermal, pH, and reusability. This study provides a novel approach in the field of clean utilization of corncob resources.