Hierarchically Structured Hollow Fiber Membranes for Efficient, Selective, and Scalable Mercury Ion Removal from Water

Mercury ions (Hg²⁺) pose serious threats to aquatic ecosystems and human health due to their high toxicity and bioaccumulation. Sulfurized polyacrylonitrile (SPAN) nanoparticles, which contain soft Lewis base groups interact strongly with the soft Lewis acid Hg²⁺, demonstrating excellent adsorption performance and chemical stability. However, traditional methods typically involve dispersing SPAN nanoparticles in water or coating them on substrates, leading to uneven distribution, poor material stability, and potential secondary pollution. To overcome challenges in mercury removal, this study presents a highly selective, regenerable, and structurally stable SPAN-integrated hollow fiber membrane fabricated by wet spinning. The hierarchical structure significantly improves pore architecture, adsorption capacity, and long-term stability. The membrane achieves an initial Hg²⁺ removal efficiency of 98.31% and retains ≈99.7% efficiency after five regeneration cycles. When integrated into a scalable purification device, it removes 90.94% of Hg²⁺ from water with an initial Hg²⁺ concentration of 4.69 mg L^-1. This work offers a novel, sustainable, and cost-effective approach for large-scale mercury remediation.