Selective extraction and determination of toxic lead based on doped metal oxide nanofiber

Abstract

Lead is considered to be one of the major water pollutants. Its persistence in nature makes it more toxic among other heavy metal ions. The current study introduced a newly developed cadmium oxide (CdO) codoped iron oxide (Fe2O3) nanofiber for selective separation of Pb(II) ions from aqueous media. The newly prepared CdO codoped Fe2O3 nanofiber was characterized by different state of the art instruments. The morphological behavior and chemical properties of the material were confirmed by field-emission scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy analysis. Different parameters, including the effect of pH, concentration, contact time and temperature were evaluated to understand the mechanism of adsorption phenomena. The maximum uptake capacity was found to be 45.75 mg/g at pH 6.0. The nature of adsorption was monolayer with homogeneous adsorption sites as suggested by Langmuir adsorption isotherm model. Kinetic studies revealed that the system followed pseudo second-order kinetic. Moreover, thermodynamic parameters displayed that the adsorption mechanism of Pb(II) onto CdO codoped Fe2O3 nanofiber was a spontaneous process and thermodynamically favorable. Selectivity studies of nine different metal ions, i.e. Cd(II), Co(II), Cr(III), Cr(VI), Cu(II), Fe(III), Ni(II), Pb(II) and Zn(II), established that CdO codoped Fe2O3 nanofiber was most selective toward Pb(II). Finally, the proposed method was further validated by applying it to real environmental water samples with satisfactory results.