Synthesis, characterization, and application of magnetic novel nanofiber membranes for the removal of heavy-metal, organic and biological pollutants from wastewater

Abstract

In the present study, magnetic novel NiFe₂O₄:Pr³⁺–MCM-41 (NiF:Pr³⁺–M) and CoFe₂O₄:Pr³⁺–MCM-41 (CoF:Pr³⁺–M) nanofiber membranes were synthesized and used as effective and efficient adsorbents for magnetic dispersive micro-solid phase extraction (d-µSPE) and the removal of Cr, Pb, Ni, As, Al, Co, Cd, and Hg, as well as organic and microbial pollutants, from industrial wastewater. The nanofiber membranes of the (NiF:Pr³⁺–M) and (CoF:Pr³⁺–M) nanocomposites were prepared by the electrospinning method. The structural and morphological characterizations of the nanofiber membranes were performed by SEM, EDX, XRD, BET analysis, TGA and FT-IR spectroscopy. XRD analyses confirmed the formation of the spinel NiFe₂O₄ and CoFe₂O₄ phases, together with the preserved amorphous MCM-41 structure, while indicating the presence of Pr and Fe oxide secondary phases in both nanocomposites. The optimized experimental conditions for the pre-concentration of Cr, Pb, Ni, As, Al, Co, Cd, and Hg were as follows: for NiF:Pr³⁺–M@PVDF, sample pH = 2; adsorption and elution contact time = 3 min; and eluent = 2 mol L⁻¹ HNO₃ (1 mL), while for CoF:Pr³⁺–M@PVDF, pH = 4, adsorption and elution contact time = 3 min; and eluent = 2 mol L⁻¹ HCl (1 mL). The pre-concentration factor, detection limit, and precision of the method were determined. The recovery results obtained from the d-µSPE-ICP-MS procedure indicated that the nanofiber membranes served as highly efficient and effective adsorbents for the separation and pre-concentration of the elements at trace levels, as well as for the removal of organic and biological pollutants from wastewater. Thus, they can be exploited for various matrices, such as sea mucilage and tap water samples. The accuracy of the method was verified by analysis of the CWW-TMD wastewater Certified Reference Material.