Preparation of α-Fe2O3/polyacrylonitrile nanofiber mat as an effective lead adsorbent

Abstract

α-Fe₂O₃ nanoparticles have been widely used in water purification because of their effective adsorption performance. However, aggregation and difficulty in separation limit their practical application. Herein, we presented a polyacrylonitrile (PAN) nanofiber mat decorated with α-Fe₂O₃ as an adsorbent for effective removal of Pb²⁺ from contaminated water, which can solve the above problems easily. The α-Fe₂O₃/PAN nanofiber mats were prepared via electrospinning followed by a facile hydrothermal method and characterized by SEM, HRTEM, FTIR and XRD. We demonstrated that the formation mechanism of α-Fe₂O₃ anchored on the PAN nanofiber surface consists of the adsorption of iron ions on the surface of PAN, and then the nucleation and growth of α-Fe₂O₃. The pH value of FeCl₃ solution has a great impact on the formation process of the α-Fe₂O₃/PAN nanofiber mat, which leads to the variation of morphology and quantity of the coating coverage. When the pH value was 2.4, polyhedral particles were coated on PAN nanofibers uniformly and the optimized α-Fe₂O₃/PAN nanofiber mat was obtained. Control experiments were carried out to quantify the adsorption capacities of different samples and adsorption kinetics. The isotherm data from our experiments fitted well to the Langmuir model and the adsorption process can be described using the pseudo-second-order model. Finally, the adsorption mechanism for Pb²⁺ was investigated and the results revealed that ion exchange between the proton of surface hydroxyl groups and Pb²⁺ accounted for the adsorption.