Efficient methotrexate adsorption on magnetic-functionalised UiO-66-NH2: Selectivity, mechanisms and recycling

Due to their non-specific toxicity, environmentally discharged anticancer drugs can significantly threaten aquatic organisms and human health. This study prepared highly stable magnetic composites with a multicore-shell structure, Fe3O4 @EDTA@UiO-66-NH2 (FEU), and their adsorption behaviour towards methotrexate (MTX, a typical anticancer drug in water) was investigated. The highest adsorption capacity of FEU for MTX reached 262.5 mg⸱g−1, much higher than most reported magnetic adsorbents. FEU showed excellent selectivity for MTX, four and nine times that of ibuprofen and sulphadiazine, respectively. Zeta potential and X-ray photoelectron spectroscopic analyses and GCMC simulations revealed that the MTX adsorption mechanism on FEU was primarily through hydrogen bonding and electrostatic interactions. Also, pH significantly affected the adsorption, guiding the study of the reversible adsorption-desorption performance of FEU. In addition, FEU exhibits good cycling performance, with only a 10% decrease in adsorption capacity after five regeneration cycles. Moreover, the composite exhibited excellent magnetic properties, allowing for rapid recovery by magnets after adsorption. This study provides new ideas for preparing materials with high adsorption performance of MTX for material recycling and sustainable use.