Synthesis of FeOOH-Loaded Aminated Polyacrylonitrile Fiber for Simultaneous Removal of Phenylphosphonic Acid and Phosphate from Aqueous Solution

Phosphorus is one of the important metabolic elements for living organisms, but excess phosphorus in water can lead to eutrophication. At present, the removal of phosphorus in water bodies mainly focuses on inorganic phosphorus, while there is still a lack of research on the removal of organic phosphorus (OP). Therefore, the degradation of OP and synchronous recovery of the produced inorganic phosphorus has important significance for the reuse of OP resources and the prevention of water eutrophication. Herein, a novel FeOOH-loaded aminated polyacrylonitrile fiber (PANAF-FeOOH) was constructed to enhance the removal of OP and phosphate. Taking phenylphosphonic acid (PPOA) as an example, the results indicated that modification of the aminated fiber was beneficial to FeOOH fixation, and the PANAF-FeOOH prepared with 0.3 mol L-1 Fe(OH)3 colloid had the best performance for OP degradation. The PANAF-FeOOH efficiently activated peroxydisulfate (PDS) for the degradation of PPOA with a removal efficiency of 99%. Moreover, the PANAF-FeOOH maintained high removal capacity for OP over five cycles as well as strong anti-interference in a coexisting ion system. In addition, the removal mechanism of PPOA by the PANAF-FeOOH was mainly attributed to the enrichment effect of PPOA adsorption on the fiber surface's special microenvironment, which was more conducive to contact with SO4•- and •OH generated by PDS activation. Furthermore, the PANAF-FeOOH prepared with 0.2 mol L-1 Fe(OH)3 colloid possessed excellent phosphate removal capacity with a maximal adsorption quantity of 9.92 mg P g-1. The adsorption kinetics and isotherms of the PANAF-FeOOH for phosphate were best depicted by pseudo-quadratic kinetics and a Langmuir isotherm model, showing a monolayer chemisorption procedure. Additionally, the phosphate removal mechanism was mainly due to the strong binding force of iron and the electrostatic force of protonated amine on the PANAF-FeOOH. In conclusion, this study provides evidence for PANAF-FeOOH as a potential material for the degradation of OP and simultaneous recovery of phosphate.