Adsorption characteristics and mechanism of tetracycline by nitrogen-rich porous carbon material derived from peony seed shell

Nitrogen-rich porous carbon (NPC) material was prepared from peony seed shell by one-step pyrolysis, and the physicochemical properties were characterized. The results showed that the as-prepared material had high surface area (3,509.1 m 2 ·g –1 ) and abundant functional groups containing nitrogen and oxygen. The NPC material displayed excellent adsorption capacity ( q e = 750 mg·g –1 ) for tetracycline (TC) even at pH = 3~11 or in the presence of salt ions ( C . NasSO4/NaCl=0 1 ~ 0.5 mol L –1 ) . With Langmuir and pseudo-second-order models, the adsorption process of being spontaneous and endothermic could be satisfactorily described and the adsorption capability was derived to be about 892.7 mg·g –1 at 25°C. The saturated NPC was regenerated by pyrolysis technology and used in the treatment of TC simulated wastewater. After 4 cycles, the adsorption amount of TC on NPC still remained above 500 mg·g –1 . Combined with the characterization analysis, it could be inferred that the adsorption of TC by NPC benefited from the high specific surface area and hierarchical pore structure of NPC, in addition to the active groups such as carbonyl, graphite-nitrogen and sp 2 carbon on its surface.