Sonochemical Preparation of a Magnet-Responsive Fe 3 O 4 @ZIF-8 Adsorbent for Efficient Cu 2+ Removal.

This work presents a novel approach to synthesizing magnetic core-shell nanocomposites, consisting of magnetic nanoparticles and a metal-organic framework, for environmental applications. The synthesis is based on the encapsulation of magnetic Fe 3 O 4 nanoparticles with microporous zeolitic imidazolate framework-8 (ZIF-8) nanocrystals via ultrasonic activation under a continuous supply of precursor solutions. This sonochemical approach is proven to be a fast, cost-effective, and controllable route for the preparation of magnet-responsive Fe 3 O 4 @ZIF-8 nanoparticles with a core-shell structure. The functional nanomaterial possesses a high content of ZIF-8 and combined micro/mesoporosity, and thus can be used as adsorbents that can be easily separated using a magnet. In particular, the sonochemically prepared Fe 3 O 4 @ZIF-8 exhibits significant adsorption performance for the removal of copper ions from water: a short adsorption time (10 min), high maximum uptake capacity (345 mg g -1 ), and excellent removal efficiency (95.3%). These performances are interpreted and discussed based on the materials characteristics of Fe 3 O 4 @ZIF-8 established by microscopy, gas sorption, X-ray diffraction, and thermal analysis.