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(NH 3 ) 6 ] 3+/2+ or [Fe(CN) 6 ] 3−/4-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.

Montmorillonite clay-modified disposable ink-jet-printed graphene electrode as a sensitive voltammetric sensor for the determination of cadmium(II) and lead(II)

“…These results are consistent with previous data on this clay mineral [49]. Some crystalline impurities associated with montmorillonite revealed by XRD data were quartz and anorthite that were eliminated by wet sedimentation during the collection of the clay fraction with particle size ≤ 2 µm [9,24,25]. The inset in Fig.…”

“…Thus, chemically modified electrodes (CMEs) represent one of the main areas of electrochemistry research with many applications including analytical chemistry [13,14], solar energy conversion [15,16], electrochromic display devices [17] and molecular electronic devices [18]. In the analytical field, different types of conductive materials were used to develop CMEs: polymers [19,20], mesoporous silicate films [21,22], nanoparticles [23] and clay minerals [9,[24][25][26][27]. Clay-modified electrodes have distinct advantages over conventional electrodes in many areas of application, such as electrocatalysis, electrochemical sensors and preconcentration electroanalysis.…”

“…For their development, different modification techniques are used to increase the sensitivity of electrochemical sensors. They include drop casting, spin coating and drop coating [9,24,25]. Montmorillonite is a natural and inexpensive clay material found in many parts of the world and composed of layers of silicates stacked on top of each other.…”