Fast and effective removal of Pb(II), Cu(II) and Ni(II) ions from aqueous solutions with TiO2 nanofibers: Synthesis, adsorption-desorption process and kinetic studies

Abstract

ABSTRACT In this study, titanium oxide (TiO2) nanofibers were synthesised and determined to be an effective adsorbent for efficient removal of Ni(II), Pb(II), Cu(II) ions from aqueous solutions. TiO2 nanofibers were synthesised by the electro-spinning method. TiO2 nanofibers were characterised with X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), X-ray spectrometer (EDX) and Fourier Transform Infrared Spectroscopy (FTIR). A series of batch adsorption experiments were done to research the influence of various parameters such as pH, adsorbent dosage, contact time, temperature, the concentration of metal ions, complexing agent on the metal ion removal capacity of TiO2 nanofibers. Adsorption equilibration time was 28 minutes and adsorption capacity was 834.56 mg g−1 for Cu(II) ions, 756.67 mg g−1 for Ni(II) ions and 685.56 mg g−1 for Pb(II) ions. The adsorption of Cu(II), Ni(II) and Pb(II) was observed maximally at pH = 6. The kinetic and isotherm model fitting studies confirmed that the data fit well with Langmuir isotherm and pseudo-second-order kinetic models. Thermodynamic studies show that the adsorption of Pb(II), Cu(II) and Ni(II) ions are endothermic, spontaneous in nature. The reusability of nanofibers for the adsorption of Ni(II), Cu(II) and Pb(II) was examined for five studies. Simultaneous adsorption of Ni(II), Cu(II) and Pb(II) from aqueous solutions was also investigated. The results showed that TiO2 nanofibers adsorbent can quickly and effectively remove heavy metals from aqueous solutions and also the adsorbent is eco-friendly, low cost, high stability and non-toxic. Also, the reusability of the material has confirmed that TiO2 nanofibers can be used many times to efficiently remove heavy metal ions from aqueous solutions.