Mechanism of a double-channel nitrogen-doped lignin-based carbon on the highly selective removal of tetracycline from water

A high-performance nitrogen-doped lignin-based carbon material (ILAC-N) was synthesized using industrial lignin and urea by hydrothermal and activation, as an absorbent of tetracycline hydrochloride (TC). The results showed that the ILAC-N comprises a double-channeled structure with micro and mesopores. It exhibits an excellent adsorption capacity of TC across a wide pH range (pH 2-11), with the highest adsorption capacity of 1396 mg g-1 at 323 K. Tests in actual wastewater showed that the TC removal rate by ILAC-N exceeded 97.4%. Moreover, it maintained a removal rate of 84% after 10 regeneration cycles, revealing its high reusability. Mechanisms suggested that pore filling and π-π interaction played a critical role in this process. In conclusion, ILAC-N can be broadly applied to livestock manure and pharmaceutical wastewater treatment, owing to its high adsorption capacity, good adsorption properties across a wide pH range, excellent reusability. Furthermore, this research opens a new path for lignin utilization.