Phytic acid modified polyacrylonitrile nanofiber membranes: Fabrication, characterization, and optimization for Pb2+ adsorption

Phytic acid (PA) modified polyacrylonitrile (PAN) nanofiber membranes for heavy metal adsorption were fabricated using electrospinning for the first time, and its mechanical properties and heavy metal adsorption under various conditions were tested. The results demonstrated that PA modification improved the mechanical properties of PAN nanofiber membranes at low modification ratio due to increased intermolecular hydrogen bonds and cross-linking. The highest breaking strength and elongation at break were 70.1% and 31.5% over PAN without modification when the PA:PAN ratio was close to 1:5. The Pb 2+ absorption tests in the water solutions demonstrated that the optimal PA:PAN ratio was 1:1, the optimal temperature was 30°C, and the optimal pH was 7. With the optimal parameters, the adsorption capacity reached the maximum and equilibrium after 4 h. The adsorption capacities increased with higher initial Pb 2+ concentrations. The highest adsorption capacity in this study was approximately 240.1 mg g −1 at the initial Pb 2+ concentration of 750.72 mg L −1 . In addition, after de-adsorption process, the 1:1 PA modified membranes maintained 91.9% re-adsorption capacities compared to primary adsorption. Consequently, the PA-modified PAN nanofiber membranes showed promising potentials of metal ion adsorption in wastewater treatment. Highlights Phytic acid modified polyacrylonitrile nanofiber membranes were fabricated. Low ratio modification improved the mechanical properties. The optimal modification ratio for Pb 2+ adsorption is 1:1. The maximum Pb 2+ adsorption capacity was 240.1 mg g −1 in this study. The membranes maintained 91.9% capacities at re-adsorption tests.