Iron-amidoximated polyacrylonitrile fiber catalyst with high intrinsic peroxidase-like activity for efficient and durable degradation of organic pollutants

PAO-Fe: Efficient and durable heterogeneous Fenton catalyst made from PAN fibers • It achieves high specific rate constants at a low H 2 O 2 -to-BPA molar ratio (11.4:1) • Effective across pH 1–7 and in real water matrices, widely applicable, recyclable • Amidoxime groups enable iron chelation and H 2 O 2 activation • Degradation intermediates have lower toxicity than BPA The development of efficient and durable heterogeneous catalysts remains a key challenge for the remediation of persistent organic pollutants via catalytic wet peroxide oxidation. In this study, polyacrylonitrile (PAN) fibers were employed as catalyst supports to meet this challenge, leveraging their robustness, versatile functionalization, and ease of separation. Amidoxime-chelated iron (AO-Fe) active sites were assembled on PAN fibers through optimized amidoximation and iron-loading conditions. The resulting catalyst (PAO-Fe) exhibits exceptionally high normalized rate constants (82.29 L/(min·mol Fe) and 0.438 L/(h·m 2 )), enabling 97.3% bisphenol A (BPA) removal within 2 h with a low H 2 O 2 dosage (H 2 O 2 -to-BPA molar ratio of 11.4:1) under mild conditions (pH 6, 30 °C). PAO-Fe operates effectively across pH 1–7, efficiently degrades various dyes and pharmaceuticals, and maintains robust activity in real water matrices. Reusability tests demonstrate good performance over five cycles with low iron leaching (<0.62 mg/L), and the spent catalyst can be readily regenerated by iron reloading. Catalytic efficiency is modulated by coexisting anions and natural organic matter in a species- and concentration-dependent manner. Mechanistic studies reveal that amidoxime groups are essential for iron chelation and facilitate H 2 O 2 activation by forming a ternary complex with BPA, generating hydroxyl radicals as the major reactive species. The degradation intermediates of BPA are assessed to have lower toxicity. This work demonstrates that fiber supports integrated with AO-Fe active sites offer a viable strategy for developing high-performance heterogeneous Fenton-like catalysts. Download: Download high-res image (249KB) Download: Download full-size image