Using iron ion-loaded aminated polyacrylonitrile fiber to efficiently remove wastewater phosphate

Wastewater phosphate removal has recently received major attention due to its contribution to eutrophication. However, existing phosphate adsorbents are most difficult to recover and recycle. Hence, this study aimed to synthesize a recyclable iron-loaded aminated polyacrylonitrile fiber (PANAF-Fe) through a facile chemical grafting reaction for phosphate removal from wastewater. Results from phosphate adsorption experiment showed that PANAF-Fe was greatly pH adaptable with an optimum pH of 6. The adsorption kinetics data were best fitted by pseudo-second-order model and equilibrium adsorption was achieved within 5 min, indicating a rapid chemical adsorption efficiency. Furthermore, Langmuir adsorption model estimated a maximum adsorption capacity of 24.14 mg P g−1, which was higher than many other adsorbents. In addition, PANAF-Fe was a promising adsorbent for phosphate removal in Cl−, NO3−, CO32−, and other coexisting ions’ solutions with an excellent reusability of minimum five times. Positively, phosphate could still be effectively removed in a continuous flow process. More importantly, phosphate concentration in actual wastewater decreased to less than 0.002 mg P L−1, lower than phosphorus threshold concentration (0.01 mg L−1) for surface water eutrophication suggested by USEPA. Altogether, this work suggested that PANAF-Fe is an environmental friendly phosphate adsorbent with high removal efficiency, low removal limit, as well as excellent reusability and recyclability.