Improvement in the performance of a Pb2+ selective potentiometric sensor using modified core/shell SiO2/Fe3O4 nano-structure

A new strategy for preparing modified carbon nanotubes paste electrode was suggested. A selective ionophore was chemically grafted onto SiO2/Fe3O4 nanoparticles, as a modified core/shell structure, for the potentiometric detection of Pb2+ ion. The surface morphology and electrical properties of the prepared electrode were characterized by scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS). The results indicated a remarkable increase in the performance in terms of Nernstian slope, selectivity, detection limit, dynamic concentration range and lifetime with high stability in the potential responses for Pb2+ ion, in comparison with the other conventional electrodes. The presence of Schiff base/SiO2/Fe3O4 in multi-walled carbon nanotubes/ionic liquid matrices of sensor leads to exhibit linear ranges of 2.50 x 10(-9)-1.00 x 10(-1) mol L-1 with a detection limit of 10(-9.02) mol L-1 for Pb2+. The suggested sensor was successfully applied to the highly sensitive determination of trace amounts of Pb2+ in various water, petrochemical waste water and biological samples with satisfactory results. (C) 2014 Elsevier B.V. All rights reserved.