The post-modification of magnetic metal–organic frameworks with β-cyclodextrin for the efficient removal of fungicides from environmental water

Abstract

Environmental water contaminated with pesticides, especially fungicides, is a persistent problem worldwide with grave public health consequences. Existing methods of removing fungicides often cannot address the problem quickly and economically. In the current work, a novel β-cyclodextrin modified Fe₃O₄@MIL-100(Fe) composite (Fe₃O₄@MIL-100(Fe)/β-CD) was synthesized and utilized as an adsorbent for the removal of fungicides from environmental water. Characterization of the adsorbent revealed that β-CD had been successfully tethered to the shell of Fe₃O₄@MIL-100(Fe) via tetrafluoroterephthalonitrile as a cross-linker. The main parameters which could affect the adsorption efficiency were investigated, such as the amount of adsorbent, pH value of the solution, adsorption equilibrium time, and ionic strength. The adsorption performance of Fe₃O₄@MIL-100(Fe)/β-CD was assessed, and the β-CD modified surface exhibited high adsorption capacities for triazole fungicides. Moreover, the regeneration of the adsorbent was explored across 5 successive cycles, and the results indicated excellent stability. Finally, the proposed material was successfully applied to the removal of four fungicides in real environmental water samples, and the adsorption efficiencies ranged from 64.52 to 102.10 mg g⁻¹. Compared with other materials, Fe₃O₄@MIL-100(Fe)/β-CD displayed outstanding adsorption capacity and a short adsorption equilibrium time, and it could offer a new platform for the removal of trace triazole fungicides in complicated matrices.