Iron-based organic framework modified Cu-Co-Fe ternary layered double hydroxide enhanced adsorptive removal of antibiotics

Abstract

Adsorption has emerged as a green and promising solution for antibiotic removal in wastewater treatment system, driving an urgent demand for designing high-performance and eco-friendly adsorbents that enable rapid, efficient elimination of antibiotic contaminants. Herein, a high-activity Fe-based metal-organic framework (Fe-MOF) was in-situ integrated with a copper-cobalt-iron layered double hydroxide (CuCoFe-LDH) via a two-step hydrothermal synthesis process, successfully fabricating an engineered Fe-MOF@CuCoFe-LDH composite adsorbent that exhibits significantly enhanced adsorption capacity and broad applicability. The Fe-MOF nanospheres were uniformly hybridized into the two-dimensional nanocluster flakes of the ternary hydrotalcite CuCoFe-LDH, forming a hierarchical heterostructure. This synergistic configuration substantially boosted the density of active surface sites on the LDH-based adsorbent, resulting in significantly improved adsorption kinetics along with enhanced absorbate-binding capacity. The removal efficiency of tetracycline antibiotic (TC) by the as-prepared Fe-MOF@CuCoFe-LDH composite reaches 94.8%, even at a high initial TC concentration of 300 mg/L, which represents a 36.7% and 9.4% increase compared to that of pristine Fe-MOF and CuCoFe-LDH, respectively. A high Langmuir maximum adsorption capacity of 2500 mg/g was achieved. The adsorption mechanism was speculated to be the metal complexation, metal-π, H-bond and electrostatic interaction as well as hydrophobic interaction. In addition, Fe-MOF@CuCoFe-LDH composite demonstrated exceptional cycling stability, retaining 97.8% TC removal efficiency through five adsorption-desorption cycles, highlighting its outstanding adaptability and promising potential for practical wastewater remediation applications.