Amino-grafting of montmorillonite improved by acid activation and application to the electroanalysis of catechol

Abstract

In this work, a natural sodium-montmorillonite clay mineral (Mt-Na) was functionalized with amine groups, either by direct grafting (Mt-NH 2 ) or via acid activation followed by grafting (MtH-NH 2 ) of [3(2-aminoethyl)amino)]propyltrimethoxysilane (AEP-TMS). The morphology and structure of the resulting composite materials were characterized by scanning electron microscopy, X-ray diffraction, N 2 adsorption-desorption isotherms (BET method) infrared spectroscopy, CHN elemental analysis and thermogravimetric analyses (TGA). The obtained organoclays were then used to modify the surface of a glassy carbon electrode (GCE), and the permselectivity and accumulation properties of the resulting films were investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS).The results indicated that MtH-NH 2 modified GCE (GCE/MtH-NH 2 ) exhibited some charge selectivity features and can be applied to the electrochemical oxidation of catechol (CT). By plotting the double logarithmic variation of anodic peak currents (Ipa) versus potential scan rate, the obtained slope value of 0.49 revealed a diffusion-controlled electron-transfer mechanisms for the redox process. The electrochemical behavior of CT on the modified electrode was also studied using differential pulse voltammetry (DPV). The sensitivities of GCE/MtH-NH 2 for CT were 1.71, 3.87 and 1.35-fold greater than signals obtained on the bare GCE, GCE/Mt-Na and GCE/Mt-NH 2 respectively, due to the ability of the aminated materials to strongly accumulate CT. After optimization, GCE/MtH-NH 2 was used for CT determination by differential pulse voltammetry that gave rise to a linear response in the concentration range from 5 µM to 80 µM (R 2 = 0.999), and to a detection limit of 0.65 µM.The proposed method was applied to CT detection in water samples and in a tea sample.

Signal amplification by electropolymerization of alizarin red S for improved diuron detection at organosmectite modified glassy carbon electrode

“…Compared with others, electrochemical methods are fast, inexpensive, miniaturizable, and offer good reproducibility, especially when the electrode is modified with materials including graphene oxide, [14] carbon nanotube, [15] conducting polymer, [16] clays, and organoclays. [17][18][19][20][21][22][23] Materials selected to be used in this study are organosmectite (since the raw clay is natural, abundant, and cheaper) and alizarin red S.…”

“…1) where major changes are observed after modification of raw clay, and they can be explained as reported in previous works in the literature. [19][20][21][22][23][24][25] Figure 1 shows the X-ray diffraction (XRD) patterns of Sa(Na) and Sa(DODAB) samples. Significant differences were observed on the main peak around 2θ = 5.5 for the basal spacing (d 001 ), which correspond, by using Bragg relation (2dsinθ = λ), to 16 Å.…”

Enhanced Ceftriaxone Determination using a Glassy Carbon Electrode Modified with a Cr‐Based Metal‐Organic Framework Film Stabilized by β‐Cyclodextrin Polymer

“…In these lines, thin film electrodes offer the advantage of easy incorporation and maintenance of modifiers to enhance sensor sensitivity and selectivity. [19][20][21][22] Another avenue of interest in electrode modification involves the use of metal-organic frameworks (MOFs), a class of porous materials. Yet, MOFs, with their tunable structure and surface chemistry, have promising applications in electroanalysis.…”

“…Electroanalysis, which measures the current generated during the oxidation or reduction of an analyte at electrodes, provides cost‐effective solutions in analytical chemistry. In these lines, thin film electrodes offer the advantage of easy incorporation and maintenance of modifiers to enhance sensor sensitivity and selectivity [19–22] . Another avenue of interest in electrode modification involves the use of metal‐organic frameworks (MOFs), a class of porous materials.…”

Mechanochemical Synthesis of Rosin-Modified Montmorillonite: A Breakthrough Approach to the Next Generation of OMMT/Rubber Nanocomposites

“…However, due to the inorganic nature of bentonite, it is not compatible with organic media and, hence, requires being organo-modified [ 7 , 8 , 9 , 10 ]. Many different methods, including ion exchange [ 11 , 12 ], grafting of organic compounds [ 13 , 14 ], acid–base reactions [ 15 ], pillaring by different types of polycations [ 16 , 17 ], ion-dipole interaction [ 11 , 18 ], etc., were applied to modify the bentonite minerals. Among these, the conventional wet cation exchange technique has been commercialized and widely used for the synthesis of organo-montmorillonite (OMMT).…”