Porous loofah sponge meets bimetallic MOF: Synergistic effect for efficient tetracycline removal

A “top-down” strategy was employed to fabricate porous loofah sponge (LS) as a robust substrate. • Fe-doped ZIF-8 was in-situ grown on LS to fabricate a novel Fe/ZIF-8@LS composite adsorbent. • The composite exhibited excellent adsorption performance for tetracycline hydrochloride. • Adsorption was driven by hydrogen bonding, pore filling, electrostatic interaction and π-π interaction. The valorization of agricultural and forestry residues is crucial for sustainable pollution control. Herein, natural loofah, a typical lignocellulosic biomass waste, was pretreated via a “top-down” method to obtain porous loofah sponge (LS). This waste-derived porous framework was then used for the in situ growth of MOF via a bimetallic doping strategy, forming the Fe/ZIF-8@LS composite. The material was characterized by FT-IR, XRD, SEM, BET, and XPS, confirming the successful incorporation of Fe into the ZIF-8 framework and its uniform loading onto LS. The resulting composite was applied to adsorb tetracycline (TC), a recalcitrant antibiotic that tends to accumulate in water and poses serious ecological and health risks. Adsorption experiments showed that Fe/ZIF-8@LS achieved a maximum TC adsorption capacity of 169.33 mg g −1 at pH 6. The adsorption process was well described by Freundlich isotherm and pseudo-second-order kinetic models, and thermodynamic results revealed its spontaneous and endothermic behavior. The underlying mechanisms involve hydrogen bonding, electrostatic interactions, π-π interactions, and coordination bond. Moreover, the material showed moderate reusability after five regeneration cycles. Collectively, this work not only enables the value-added utilization of agricultural and forestry waste, but also achieves the goal of “treating waste with waste” by using the resulting composite for efficient TC removal from aqueous environments. Download: Download high-res image (360KB) Download: Download full-size image