Facile fabrication of N-doped hierarchical porous carbons derived from soft-templated ZIF-8 for enhanced adsorptive removal of tetracycline hydrochloride from water

Abstract

N-doped hierarchical porous carbons (NHPCs) were successfully prepared from soft-templated zeolitic imidazolate framework-8 (ZIF-8) precursors using sodium dodecylbenzene sulfonate (SDBS) as a template through facile one-step carbonization and applied in tetracycline hydrochloride (TCH) adsorption. The NHPC synthesized at 1000 °C with an SDBS/Zn²⁺ molar ratio of 0.075 exhibited the highest TCH adsorption (q_m = 80.92 mg g^-1) owing to its relatively large BET surface area (1067.41 m² g^-1) and pore volume (1.22 cm³ g^-1) and the stronger surface interaction between TCH and NHPCs (HC1000-0.075). Compared with surfactant-free ZIF-8-derived carbon (HC), introduction of SDBS in the ZIF-8 precursor not only improved the pore structure of the carbon materials but also increased the nitrogen content and the number of surface functional groups. Adsorption kinetics and isotherms showed that the pseudo-second-order model and Sips model fit the TCH adsorption behavior on HC and HC1000-0.075 well. Adsorption experiments and characterizations revealed that the adsorption mechanism involved in TCH adsorption on HC1000-0.075 mainly depended on the synergistic effect of pore filling, H-bonding, π-π interactions, and weak electrostatic interactions. This study provides an effective and simple strategy for fabricating MOF-derived NHPCs as a promising adsorbent for the removal of antibiotics from water.

Keywords: Adsorption; N-doped hierarchical porous carbons; Soft template; Tetracycline hydrochloride; ZIF-8.