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    Efficient adsorption of lead (II) and copper (II) from aqueous phase using oxidized multiwalled carbon nanotubes/polypyrrole composite
    (Taylor & Francis Inc, 2018) Nyairo, Wilfrida Nyanduko; Eker, Yasin Ramazan; Kowenje, Chrispin; Akin, Ilker; Bingol, Haluk; Tor, Ali; Ongeri, David Mokono
    Polypyrrole coated oxidized multiwalled carbon nanotubes (oMWCNT/Ppy) were applied to determine the adsorption characteristics of Pb(II) and Cu(II) from their aqueous solutions. Structural and morphological characterization studies using scanning electron microscopy, thermogravimetric analysis, Fourier transform infrared and Raman spectroscopy showed successful preparation of the oMWCNT/Ppy composite. The influence of pH, contact time, and initial metal ion concentration on the adsorption of Pb(II) and Cu(II) was studied. The adsorption processes fitted well with Langmuir isotherm and pseudo-second-order kinetic models. The maximum adsorption capacities for Pb(II) and Cu(II) were determined as 26.32 and 24.39mg/g, respectively. Desorption studies indicated that the oMWCNT/Ppy composite could be reused for five cycles with minimum loss of its initial adsorption capacity.
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    Efficient Removal of Lead(II) Ions from Aqueous Solutions Using Methyl-?-Cyclodextrin Modified Graphene Oxide
    (Springer, 2017) Nyairo, Wilfrida Nyanduko; Eker, Yasin Ramazan; Kowenje, Chrispin; Zor, Erhan; Bingol, Haluk; Tor, Ali; Ongeri, David Mokono
    Graphene oxide (GO) and graphene oxide modified with methyl-beta-cyclodextrin denoted as GO-m beta CD were prepared and applied as adsorbents to determine the adsorption characteristics of Pb(II) from aqueous solutions. The characteristic results of Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), Raman spectroscopy, and scanning electron microscopy (SEM) showed that m beta CD was successfully physically attached to GO to form the GO-m beta CD nano-composite. The adsorption equilibrium and kinetics of the adsorbents were well described by Langmuir isotherm and pseudo-second-order models, respectively. The maximum Pb(II) adsorption capacity of GO-m beta CD (at pH = 6 and room temperature) was determined as 312.5 mg/g which was significantly higher than that of GO (217.39 mg/g). This indicates that the modification of GO with m beta CD enhances the adsorption capacity of GO. The desorption studies show that the adsorbent GO-m beta CD can be used for at least five cycles with non-significant loss of its initial adsorption capacity for Pb(II) ions.