Polymer‐Based Amine‐Functionalized Lignin Nanofibrous Membranes With Organic–Inorganic Hybrid Structure for Efficient Removal of Cu ²⁺ and Zn ²⁺

ABSTRACT

Heavy metal contamination is a serious environmental concern, while conventional adsorbents often have too few accessible active sites and limited reusability. In this study, a polymer‐based amine‐functionalized lignin nanofibrous membrane (AL‐NH ₂ ‐PVA@SiO ₂ ‐NH ₂ ) was fabricated by electrospinning combined with silane‐assisted crosslinking, forming a porous organic–inorganic hybrid network with improved structural stability and greater accessibility of active sites. The membrane showed high adsorption performance for Cu ²⁺ and Zn ²⁺ , with maximum adsorption capacities of 193.42 and 165.83 mg g ⁻¹ , respectively. The adsorption process reached equilibrium within 120 min and was described by the pseudo‐second‐order kinetic model and Langmuir isotherm, suggesting a chemisorption‐dominated mechanism with monolayer coverage. Thermodynamic analysis showed that adsorption was spontaneous and endothermic. Analysis of the mechanism indicated that adsorption mainly involved coordination interactions between metal ions and amino functional groups (NH ₂ ), accompanied by electrostatic attraction from deprotonated COO ⁻ groups. In addition, the interconnected hybrid nanofibrous structure increases surface area, facilitates ion diffusion, and improves structural robustness. The material retained over 68% of its initial adsorption capacity after five regeneration cycles. Overall, polymer functionalization and hybrid structural design act synergistically to enable efficient heavy metal removal, offering a sustainable strategy for lignin valorization.