Endeavoring a High Amidoxime Utilization Ratio and Adsorption Capacity for Uranium Extraction From Seawater: A Hydrogen Bonding Reconstruction Strategy

Abstract Functionalized amidoxime [AO, R−C(NH₂)═N(OH)] is widely used for uranium extraction from seawater, but increasing the effective functional sites for high AO utilization in adsorbents remains challenging. This study introduces a hydrogen bond reconstruction strategy to enhance uranium extraction efficiency of AO‐modified polyacrylonitrile (PAN) fibers by blending with polyvinyl alcohol (PVA). The PAN/PVA fibers are synthesized via electrospinning, followed by amidoximation on PAN to prepare PAN‐AO/PVA adsorbents. These materials can extract uranyl ions from the uranyl‐carbonate complex in seawater, achieving an adsorption capacity of 21.0 mg g⁻¹ under simulated seawater conditions with 330 ppb uranium concentration over 24 h. PVA blending increases AO utilization efficiency by 4 times (from 1/291 to 1/69), exceeding most reported values. The adsorbent also shows excellent reusability, retaining over 95% capacity after seven adsorption–desorption cycles. Quantum‐chemical studies based on density functional theory reveal that PVA modulates the hydrogen bonding network by shifting intramolecular bonds in PAN‐AO to intermolecular ones with PVA, increasing permeability and exposing more active N and O sites. Additionally, PVA's hydroxyl groups coordinate with UO₂²⁺, enhancing uranyl adsorption through an enthalpy‐entropy synergy relationship. This strategy offers a practical approach to improving uranium extraction from seawater.