Fast and simultaneous removal of microplastics and plastic-derived endocrine disruptors using a magnetic ZIF-8 nanocomposite

Microplastics are extremely prevalent materials, posing risks to both the environment and human health. Considerable, further impact, from the endocrine disrupting phenolic compounds generated via the degradation of plastic waste is a key concern. Magnetic sorbents have been shown to be effective in the removal of microplastics, however there is a lack of cost-effective and environmentally friendly magnetic micro/nanomaterials for integrated and efficient removal of microplastics and endocrine disrupting phenols from water. Herein, a zeolitic imidazolate framework (ZIF-8) magnetic porous nanocomposite modulated with n-butylamine (nano-Fe@ZIF-8) has been synthesised in water at room temperature. The prepared nano-Fe@ZIF-8 was characterized via scanning electron microscopy, powder X-ray diffraction and nitrogen adsorption measurements. Nano-Fe@ZIF-8 enabled the fast and simultaneous removal of both polystyrene microspheres (1.1 µm diameter) and endocrine disrupting phenols (bisphenol A and 4-tert-butylphenol). Nano-Fe@ZIF-8 showed a higher removal efficiency compared with unmodulated Fe@ZIF-8 and under optimal conditions nano-Fe@ZIF-8 (20 mg) was able to remove ≥ 98 % of polystyrene microspheres at high concentration (25 mg L-1) within 5 min, as well as remove ≥ 94 % of both bisphenol A (1 mg L-1) and 4-tert-butylphenol (1 mg L-1) within the same time frame. Nano-Fe@ZIF-8 showed comparable efficiency in the removal of polystyrene microspheres and a greatly improved extraction performance for the two selected endocrine disrupting phenols when compared with oleic and azelaic acid functionalised Fe3O4 magnetic nanoparticles. The results illustrate the synthesis of a simple, environmentally friendly, and high performing material for the fast removal of both soluble organic pollutants and microparticulated organic pollutants.