Defluoridation performance of electrospun La₂O₃-CeO₂ nanofibers

Nano bimetallic oxides have broad application prospects as fluoride removal agents. La₂O₃-CeO₂ nanofibers were fabricated via electrospinning-calcination method using Ce(NO₃)₃·6H₂O and La(NO₃)₃·6H₂O as raw materials and polyacrylonitrile (PAN) as template. TEM, SEM-EDS, BET, FTIR and XRD were employed to verify the morphology and structure of La₂O₃-CeO₂ nanofibers. The defluoridation properties of La₂O₃-CeO₂ nanofibers were discussed under batch mode, and the effects of adsorbate (F⁻) initial concentration, pH, contact time, La₂O₃-CeO₂ nanofibers dose and coexisting anions on the defluoridation were explored. The results illustrate that the specific surface area of La₂O₃-CeO₂ adsorbent is 31.04 m²·g⁻¹. The La₂O₃-CeO₂ nanofibers exhibit the best defluoridation performance at pH of 3, and the adsorption capacity of La₂O₃-CeO₂ nanofibers climbs up with rise of the initial concentration of F⁻. The pseudo-second-order kinetic and Langmuir isotherm model (R²>0.99) simulate the defluoridation process of La₂O₃-CeO₂ nanofibers better, and the maximum uptake of F⁻ by La₂O₃-CeO₂ nanofibers is 111.98 mg·g⁻¹ at 45℃. Thermodynamic studies suggest that the defluoridation process of La₂O₃-CeO₂ nanofibers is a spontaneous (ΔG⁰<0), entropy increase (ΔS⁰=56.63 J·mol⁻¹·K⁻¹) and endothermic (ΔH⁰=9.90 kJ·mol⁻¹) process.