Excellent fluoride removal performance by electrospun La–Mn bimetal oxide nanofibers

Abstract

La–Mn bimetal oxide nanofibers, used as an adsorbent for the defluoridation of water, were synthesized by an electrospinning and heat treatment technology. The La–Mn bimetal oxide nanofiber adsorbent with a specific surface area of 35.064 m² g⁻¹ displayed a good defluoridation performance. Both the adsorption kinetics and equilibrium for fluoride (F⁻) uptake onto La–Mn bimetal oxide nanofibers were investigated. The kinetic studies established that the adsorption attained equilibrium at about 90 min, and the PSO kinetic model was ideal for the kinetic data under 20 and 50 mg L⁻¹. The Langmuir maximum F⁻ uptake was computed to be 189.39 mg g⁻¹ at 308 K and pH 3. A thermodynamic study affirmed a feasible, endothermic, spontaneous and entropy driven process of F⁻ adsorption towards La–Mn bimetal oxide nanofibers at the studied temperature range. Except for the competitive adsorption of PO₄³⁻ and F⁻, the presence of NO₃⁻, CO₃²⁻, Cl⁻ and SO₄²⁻ had little effect on fluoride removal. The La–Mn bimetal oxide adsorbent exhibited a good reusability.