Interfacial engineering of a PAN-PBAs-PA composite membrane with secondary Ni2+ curing for highly selective removal of cesium

Secondary Ni 2+ curing enhances the loading stability of Prussian blue analogs. • Integration of adsorption and separation enables efficient cesium removal • The incorporation of PA layer enhances the anti-interference capability. • The prepared membrane achieves over 99% Cs + removal efficiency in high-Cs + solution. With the rapid expansion of nuclear energy, radioactive cesium ( 137 Cs) contamination poses severe ecological and human health hazards due to its long half-life (30.2 years), intense γ-radioactivity, and high aqueous mobility. Conventional remediation technologies remain constrained by inadequate selectivity, excessive energy consumption, and the generation of secondary pollutants. Although membrane-based separation affords continuous processing, conventional membranes typically exhibit insufficient Cs + selectivity. Prussian blue analogs (PBAs) are highly promising for Cs + capture because their crystallographic lattice channels enable size/fit-assisted ion sieving. However, their practical performance is often impeded by PBAs particle aggregation and weak adhesion to membrane substrate. Herein this study presents a PAN-PBAs-PA composite membrane with an interracially engineered architecture, fabricated via a four-step strategy: alkalization, in-situ PBAs growth, secondary Ni 2+ curing, and interfacial polymerization (IP). This design enables efficient and selective removal of Cs + from aqueous media. A systematic optimization was conducted for the secondary Ni 2+ curing parameters and for IP conditions. Optimized secondary Ni 2+ curing conditions (30 mmol·L −1 NiCl 2 , 5 min), uniformly dispersed, highly crystalline Ni Fe PBA nanoparticles were achieved, affording an equilibrium Cs + adsorption capacity of 485 mg·m −2 IP optimization (0.2 wt% PIP, 0.02 wt% TMC, 5 min) further delivered composite membranes exhibiting nearly complete rejection of 2 ppm Cs + (≈100%), while maintaining high selectivity against coexisting salts, with 85% rejection for MgCl 2 , and 92% rejection for Na 2 SO 4 . Meanwhile, the resulting membranes demonstrated markedly enhanced thermal and structural stability. Mechanistically, the secondary Ni 2+ curing strategy promotes robust PBAs anchoring through regulating nucleation and growth at the membrane interface. Benefiting from synergistic size-sieving by PBAs lattice and electrostatic partitioning (Donnan effects) imposed by the PA layer, the membranes achieve enable superior Cs + selectivity. This work provides novel insights into PBAs-membrane interfacial engineering and offers an effective materials platform for advanced nuclear wastewater treatment. Download: Download high-res image (200KB) Download: Download full-size image