Boosting highly capture of trace tetracycline with a novel water-resistant and magnetic (ZIF-8)-on-(Cu-BTC@Fe3O4) composite

Merging two distinct metal-organic frameworks (MOFs) together to construct one syntagmatic adsorbent could coordinate the discrepant performances of each MOF. Herein, a new type of MOF-on-MOF was successfully obtained through a two-step hydrothermal synthesis process with a surfactant assistant (polyvinylpyrrolidone, PVP), involving pre-synthesized host [email protected]3O4 support as the seed in the first step and then growing guest ZIF-8 particles on its surface in the second step to form (ZIF-8)-on-([email protected]3O4) hybrids. Attributing to the synergistic enhanced adsorption of the double MOF units, the (ZIF-8)-on-([email protected]3O4) possesses excellent adsorption performance towards tetracycline (TC) such as higher uptake capacity, rapid adsorption rate, convenient solid-liquid separation, etc. Importantly, it exhibits highly durable in water. The saturated adsorbents can be readily recycled with solvent washing method, and approximately 90% of the TC uptakes achieved even after fifth round.