Nanohybrid materials from amine functionalization of sepiolite: Preparation, characterization and application as electrode modifiers for the electroanalytical detection of heavy metal ions

Abstract

Sepiolite-based organic–inorganic hybrid materials bearing amine groups were prepared by chemical grafting using 3-aminopropyltriethoxysilane (APTES) and [(3-(2-aminoethylamino)propyl)]trimethoxysilane (AEPTMS). The structural properties of the pristine sepiolite and the obtained composites materials were analysed using XRD, TG/DTA analysis and FTIR. The surface ion exchange ability of the functionalized clay minerals coated as thin film on glassy carbon electrodes and exposed to [Ru(NH3)6] or [Fe(CN)6] electroactive probes was also investigated by multisweep cyclic voltammetry (MSCV) and by Electrochemical impedance spectroscopy (EIS). From MSCV data, it was found that sepiolite and organosepiolites display a permselective behavior depending on the charge on its surface while EIS results showed that the functionalization of sepiolite enhanced its conductivity. The organosepiolites were tested in a comparative way for the voltammetric detection of mercury (II), and some preliminary experiments based on differential pulse voltammetry highlighted the interest of using the most sensitive organoclay (i.e. the sample grafted by AEPTMS) for the electroanalysis of several heavy metals in the same solution. Correspondence to: Ignas Kenfack Tonle, Chemistry of Materials and Electrochemistry, Department of Chemistry, Faculty of Science, University of Dschang, P.O. Box 67 Dschang, Cameroon, Tel: +237 696 141 545; Fax: +237 245 507 092; E-mail: ignas.tonle@univ-dschang.org