Microwave-assisted synthesis of ZIF-67(Co)-based composite for efficient separation of oils and organic contaminants from water

Abstract

Oil pollution and industrial organic contaminants pose risks to aquatic ecosystems and human health, creating a need for sorbent materials that combine high efficiency, selectivity, and durability. Herein, we report a hierarchical metal-organic framework-based composite sorbent prepared via a rapid two-step microwave-assisted strategy. In the first step, cobalt hydroxide nanosheet arrays were uniformly grown on fluorine-modified carbon fibers using a pulsed microwave-assisted approach, enabling ultrafast nanostructure formation. In the second step, zeolitic imidazolate framework-67 nanocrystals were deposited onto the nanosheets, yielding a hierarchical architecture with nanoscale crystallites and microporosity. The composite exhibited a transition from hydrophobic/oleophilic to superhydrophobic/superoleophilic behavior, enabling efficient and selective oil/water separation. Sorption tests revealed high uptake capacities (84–321 wt.%) across a broad range of organic liquids, surpassing many previously reported metal-organic framework-based sorbents. The composite also enabled the treatment of surfactant-stabilized oil-in-water emulsions, achieving 76% diesel removal within 30 minutes. Moreover, the material demonstrated excellent reusability and stability under repeated cycling and harsh experimental conditions, retaining both structural integrity and sorption performance. The developed synthesis strategy enables rapid fabrication of highly efficient sorbents for environmental remediation and provides experimental insights broadly relevant for the design of other metal-organic framework-derived composites with hierarchical structures.