Preparation of Organophilic Nanohybrid Kaolinite and Application to the Electrochemical Detection of Organic Pesticide

Abstract

Novel organophilic nanohybrid materials (K‐TDD) were obtained by the grafting of 1,2‐tetradecanediol (TDD) onto the surface of kaolinite (K). XRD, IR, TGA‐DTG, and SEM characterization showed that TDD grafting results in a partial exfoliation of kaolinite layers. This material was used to modify a glassy carbon electrode (GCE/K‐TDD) and applied for the trace analysis of methyl parathion (MP). The signal of MP recorded on GCE/K‐TDD was more intense compared to the unmodified GCE or to one modified with a film of natural kaolinite. Several parameters that can affect the stripping response were systematically investigated to optimize the sensitivity of the organokaolinite‐modified electrode. A linear calibration curve for MP was obtained in the concentration range from 2×10−6 to 14×10−6 mol .L−1 in acetate buffer (pH 6), giving a detection limit of 9×10−8 mol .L−1. The sensitivity of the method was found to be 2.42 μA/μM for the range of concentrations that gives a linear calibration curve. The electrode was shown to be very stable, with the electrochemical response of MP decreasing by only 1.5 % after a series of nine measurements. The interference of various inorganic ions and organic compounds likely to influence the stripping determination of the MP were also examined. The results showed that the GCE/K‐TDD electrode was effective in solutions containing interfering species and could be applied for the quantification of MP pesticide in natural water.

Kaolinite‐based Hybrid Material from Interlayer Grafting of 1‐(2‐Hydroxyethyl)piperazine and Application to the Sensitive Voltammetric Detection of Lead

“…FTIR spectra of K, K-DMSO and grafted kaolinite K-HEP are presented in Figure 3. The results obtained for pristine kaolinite (K) (Figure 3a) and K-DMSO (Figure 3b) are similar to those obtained in previous work [43,50,[57][58][59]. Briefly, the absorption bands of kaolinite at 3692, 3668 and 3651 cm À 1 correspond to interlayer hydroxyl stretching while the band observed at 3620 cm À 1 corresponds to the stretching vibrations of the internal hydroxyl group.…”

“…TGA and DTG curves of K, K-DMSO, K-HEP, recorded between room temperature and 1000 °C are presented in Figure 2. The results obtained in the case of pure kaolinite (K) (Figure 2a) and in the case of K-DMSO (Figure 2b) are similar to those obtained in previous work [58,59]. The mass losses at 511 °C (12.85 %) for pure kaolinite (Figure 2a) and at 508 °C (11.50 %) for K-DMSO (Figure 2b) correspond to the dehydroxylation of the inorganic structure of kaolinite.…”

“…The kaolinite and organokaolinite working electrodes were prepared according to previously published procedures [18, 19, 28–30, 42, 43, 59]. In practice, the glassy carbon electrode (GCE) was first polished with an aqueous suspension of 0.05 mm aluminum, rinsed thoroughly with deionized water, irradiated under ultrasound in deionized water for 10 min, and dried at room temperature.…”

“…The natural clay mineral used in this work is the wellknown KGa-1b kaolinite sample (denoted as K after purification) [38,48,[57][58][59]. Its purification was done according to previously published procedures [57][58][59].…”

“…The natural clay mineral used in this work is the wellknown KGa-1b kaolinite sample (denoted as K after purification) [38,48,[57][58][59]. Its purification was done according to previously published procedures [57][58][59]. 1-(2-hydroxylethyl)piperazine (HEP) (99 %) used to modify the pure kaolinite was purchased from Sigma-Aldrich.…”