High-Density Iron Nanostructures Grown on Electrospun PVA/Pectin Fibers via Seed-Mediated Strategy for As(V) Remediation.

Effective arsenic remediation requires maximizing the loading and accessibility of active iron phases, a persistent challenge that has limited the development of practical superadsorbents. Here, a seed-assisted anisotropic growth strategy is applied to electrospun poly(vinyl alcohol)/pectin nanofibers by sequentially introducing Fe2+ and Fe3+ ions. This dual-ion approach generates ∼2-nm iron seeds that direct the growth of rice-grain-like iron oxyhydroxide nanostructures (29 ± 6 nm × 110 ± 20 nm; aspect ratio ∼4), achieving loadings and surface accessibility unattainable with conventional single-doping. The resulting morphology exhibits a high iron content (1.72% at, a 12-fold increase over single-ion doping [0.04%-0.14%]), yielding a superadsorbent that reduces As(V) from 1 mg L-1 at pH 6 to below the WHO guideline (10 µg L-1, ∼99% removal) using only 1 g L-1 dose. High removal efficiency is retained at neutral and basic pH (∼30 µg L-1), substantially outperforming single-doped materials ([245 ± 15] µg L-1, ∼75% removal). Structural analysis (FE-SEM, EDS, SAXS, WAXS) elucidates the seed-mediated growth mechanism, whereas kinetic and isotherm studies indicate chemisorption and accelerated cooperative binding. The material is reusable over several cycles, and remains effective in the presence of competing ions, establishing seed-mediated growth as a powerful route to high-performance nanostructured superadsorbents.