Imine Nanomaterial Composites as Receptors for Potentiometric and Voltammetric Sensing of Ions

Abstract

This doctoral thesis provides an insight into the development, characterization and application of potentiometric and voltammetric sensor based on Schiff base ionophores (E)-3-((2- aminoethylimino)methyl)-4H-chromen-4-one (IFE), (E)-3-(((2-((2 aminoethyl) amino) ethyl) imino) methyl)-4H-chromen-4-one (ICU) and (E)-3-((2-(2-(2-aminoethylamino) ethylamino) ethylimino)methyl)-4H-chromen-4-one (IFE(III)). These prepared sensors provide better selectivity for the target species (heavy metals of environmental importance). The present thesis work can be divided into two main parts. First approach is the development of ion selective electrodes (ISE) based on modification with multiwalled carbon nanotubes (MWCNTs). It consists of incorporation of multiwalled carbon nanotubes in the polymeric membrane in order to provide improved characteristics of the ISEs. Second approach is the development of voltammetric sensors for the detection of cations using cyclic voltammetry and differential pulse voltammetric techniques. Potentiometric and voltammetric sensor for creating cationic response for Fe(II) based on (E)- 3-((2-aminoethylimino)methyl)-4H-chromen-4-one (IFE) is introduced. The influence of variables including amount of ionophore, plasticizers, anion excluder and multiwalled carbon nanotubes (MWCNTs) on the performance of the potentiometric sensor were investigated. The sensor for Fe(II) improvised the dynamic linear range (1×10-7 to 1×10-1 mol/L) with a slope of 27 mV/decade and a detection limit of 2.5×10-8 mol/L. Selectivity of the ion selective electrode improved after modification with MWCNTs. The reduction and oxidation properties of IFE were studied by voltammetric measurements. Differential pulse voltammetry was applied to the optimized electrode and a linear dynamic range from (9.9×10-7 to 2.9×10-5 mol/L) with a detection limit of 6.13×10-8 mol/L was obtained. The composition and morphology of the modified ion selective electrode were characterized with scanning electron microscopy.