Biohybrid Sm2O3-amyloid nanofibrous membranes for highly efficient adsorptive filtration of Pb(II) and Cd(II)

A biohybrid nanofibrous membrane comprising lysozyme amyloid fibrils (LAFs) and plant extract-mediated samarium oxide nanoparticles (Sm 2 O 3 NPs) was developed via self-assembly for continuous-flow heavy metal removal. The hierarchical architecture featured a macroporous honeycomb network and uniform ~2.9 nm inter-fibrillar spacing, yielding 74.3% porosity and high hydrophilicity (water contact angle: 31.8°). Under continuous-flow filtration, a single pass reduced 0.1 mg/L Pb(II) to an ultra-trace level of 0.0045 mg/L (95.5% removal), strictly meeting WHO drinking water guidelines, while Cd(II) removal reached ~91%. Langmuir analysis revealed a maximum adsorption capacity of 62.3 mg/g and high affinity ( K L =3.367×10 4 M -1 ) for Pb(II). Furthermore, Dubinin-Radushkevich modeling confirmed a predominantly chemisorption-driven adsorption process. The preferential binding affinity toward Pb(II) over Cd(II) was mechanistically consistent with Pearson's Hard-Soft Acid-Base (HSAB) principle and differences in hydration energy. In highly competitive matrices, Pb(II) removal remained robust at 92.9% in tap water and 82.1% in NOM-rich turbid wastewater. Extended continuous-flow filtration demonstrated highly stable hydrodynamic performance (steady-state flux ~61%), preserved structural morphology, minimal mass loss (~0.8%), and only trace Sm leaching (~1.8 ppb). These findings establish the LAFs-Sm 2 O 3 membrane as a promising platform for sustainable, decentralized point-of-use water purification.