An 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 systems, driving an urgent demand for designing high-performance and eco-friendly adsorbents that enable rapid and 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 adsorbate-binding capacity. The removal efficiency of the 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⁻¹, 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⁻¹ was achieved. The adsorption mechanism was speculated to involve metal complexation, metal–π, H-bonding and electrostatic interactions as well as hydrophobic interactions. In addition, the Fe-MOF@CuCoFe-LDH composite demonstrated exceptional cycling stability, retaining 97.8% TC removal efficiency for five adsorption–desorption cycles, highlighting its outstanding adaptability and promising potential for practical wastewater remediation applications.