High-capacity and regenerable arsenic adsorbent via one-step amination of polyacrylonitrile fibers

Aminated polyacrylonitrile (PAN) fibers were developed via one-step diethylenetriamine modification for efficient As(V) removal from water. The amination process, optimized at 90 °C for 4 h, achieved an exceptional maximum As(V) adsorption capacity (qm, Langmuir model) of 282.2 mg/g at 25 °C, representing one of the highest capacities reported for fibrous adsorbents and exceeding conventional metal oxide adsorbents by 3–5 fold. The aminated fibers demonstrated remarkable selectivity in complex water matrices, maintaining >82% removal efficiency even when competing anions were present at five-fold excess concentrations. FTIR analysis confirmed successful nitrile-to-amine conversion, evidenced by the disappearance of characteristic –C ≡ N bands and the emergence of N–H and C–N stretching vibrations, while preserving the fibrous morphology essential for practical applications. The adsorbent exhibited exceptional regenerability, maintaining >95% capacity over 10 consecutive cycles using mild acid regeneration, thereby reducing lifecycle costs by an order of magnitude compared to single-use materials.The combination of high capacity, superior selectivity, excellent regenerability, and compatibility with existing filtration infrastructure positions aminated PAN fibers as a commercially viable and sustainable solution for addressing global arsenic contamination challenges, particularly in resource-limited settings where cost-effectiveness and operational simplicity are critical.