Hierarchically porous ZIF-8 for tetracycline hydrochloride elimination

Herein, hierarchically porous ZIF-8 (HZIF-8) adsorbents were prepared successfully with the assistance of sodium dodecyl sulfonate (SDS) through a facile one-pot self-assembly method at room temperature, and their adsorption of tetracycline hydrochloride (TCH) was studied in water by bath adsorption experiments. The structural characteristics of the adsorbents were confirmed by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR), and N2 adsorption/desorption measurements. The research results indicated that the final hierarchically porous ZIF-8 with a large Brunauer–Emmett–Teller (BET) specific surface area (1423.78 m2 g−1) had a higher TCH adsorption capacity (574.71 mg g−1) than microporous ZIF-8 by improving the mass transfer rate. The adsorption isotherm was expressed well by the Freundlich isotherm model and the kinetic data fit the pseudo-second-order kinetic model better. Mechanistic studies implied that coordinate bonds, π–π interactions and electrostatic interactions played vital roles in the TCH adsorption process based on the effect of pH, zeta potential of adsorbents, and X-ray photoelectron spectroscopy (XPS). Moreover, the addition of SDS altered the ZIF-8 porosity and exposed more active sites of adsorbents. As synthesized, the hierarchically porous ZIF-8 displayed excellent regenerability and could be expected to expand the application range regarding the removal of antibiotics from aqueous solution.