A novel flower-like nickel-metal-organic framework (Ni-MOF) membrane for efficient multi-component pollutants removal by gravity

The recycling of wastewater containing multiple pollutants is an urgent issue that requires sustainable and effective solutions. Gravity-driven membrane separation is a highly promising technology due to its low energy consumption, low transmembrane pressure, and ease of operation. To further enhance its advantages, this work explores the use of metal-organic frameworks (MOFs) for membrane modifications, which possess a porous structure, stable chemical properties, and high specific surface area. Specifically, flower-like nickel-based MOF particles were synthesized and assembled on a nylon membrane to prepare a novel Ni-MOF membrane. The NiMOF membrane displayed superhydrophilic properties, as evidenced by a water contact angle of 0 degrees, and underwater superoleophobic properties, with an underwater oil contact angle of 154.37 degrees. The Ni-MOF membrane demonstrated a significantly improved rejection rate for four types of dye solutions, particularly Congo red solution, which was rejected at a rate of 97.71% only through gravity-driven separation. Additionally, the NiMOF membrane exhibited exceptional performance for oil-water emulsion and microplastic wastewater, which was evidenced by the rejection of 95% and 99%, respectively. Moreover, the cycling tests revealed that the Ni-MOF membrane equipped long-term stability. These data demonstrated the Ni-MOF membrane had broad application prospects in the separation of wastewater containing multi-component pollutants.