Abstract:
Magnetite (Fe3O4) was produced using co-precipitation method while polyaniline (PANI) and
Fe3O4/PANI nanocomposite were synthesized using in-situ polymerization of aniline in aqueous
solution of Fe3O4 in the presence of oleic acid and sodium dodecayl sulphate (SDS). The ternary
system (Fe3O4/PANI/Chitosan) composite was formed by blending the binary nanocomposite
with chitosan. Structural and morphological properties of the as produced material were
characterized using X-ray diffraction (XRD), Scanning electron microscope (SEM/EDX),
Fourier transformed infrared and Uv-vis spectroscopy. The XRD pattern indicated semi
crystalline structure of PANI, amorphous structure of magnetite but Fe3O4/PANI and
Fe3O4/PANI/Chitosan have crystalline structures. Moreover, electrochemical behaviors of glassy
carbon (GC) electrode modified by the as prepared nanomaterials was characterized using cyclic
voltammetry in the presence of K3Fe(CN)6, in 1 M H2SO4 and 0.2 M phosphate buffer (PBS)/ 0.1 M KCl. The result depicted that Fe3O4 modified GCE is more electroactive compare to other
modified electrodes. Besides, all modified electrodes in 1 M H2SO4 showed a reversible process
whereas in buffer solution (pH 7) an irreversible electrochemical behavior was observed. Before
utilizing GCE/Fe3O4/ PANI/Chitosan as a sensor for toxic heavy metals experimental parameters
such as pH and deposition time were optimized. GCE/PANI, GCE/Fe3O4/PANI and
GCE/Fe3O4/PANI/Chitosan were used as a sensor for the determination of Cd(II) and Pb(II) ions
in standard solution with the concentration range from 10 to 50 ppm at optimum pH 7 and
deposition time of 3min in 0.2 M PBS/0.1 M KCl using differential pulse anodic stripping
voltammetry . The GCE/Fe3O4/PANI/Chitosan sensor exhibited a linear range of 10 to 50 ppm,
20 to 50 ppm, sensitivity 0.068 µA/ppm, 0.027 µA/ppm and detection limit 4.3 ppm, 4.3 ppm for
Cd(II) and Pb(II) ions, respectively. The sensor was also used to determine the amount of Cd(II)
and Pb(II) ions in water collected from Haramaya university waste water disposal and the
concentration of Cd(II) and Pb(II) ions was 39.93 ppm and 17.14 ppm, respectively. Therefore,
GCE/Fe3O4/PANI/Chitosan sensor can be a good alternative for the determination of toxic
heavy metals in waste water samples
