Electrochemical properties of carbon nanotubes/PANI/metal oxide nanoparticle nanocomposites towards electrocatalysis of some organochlorine pesticides

MSc (Chemistry), North-West University, Mafikeng Campus, 2018

This work describes the chemical synthesis of antimony ox ide nanoparticles (AONPs), polyaniline (PA I), acid functionalized single-walled carbon nanotubes (fSWC Ts) and the nanocomposite (AONP-PA 1-SWC T) as composite material for the trace detection of lindane and endosulfan (EDS). Successful synthesis of the nanomaterials was confirmed by fourier transform infrared spectroscopy (FT-IR), ultraviolet-visible (UV-Vis) spectrophotometry, x-ray diffraction (XRD) spectroscopy and scanning electron microscopy (SEM). Drop-cast method was used to modify glassy carbon electrode (GCE) with the synthesized nanomaterials. Electrochemical behaviour of the modified electrodes was explored using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) using the ferricyanide/ferrocyanide ([Fe(CN)6]4-/[Fe(CN)6]3-) redox probe. AONP-PANI-SWC T modified GCE exhibited faster electron transport properties as well as enhanced catalytic current response as compared to bare-GCE, GCE-AONPs, GCE-PA I, and GCE-SWC T. Electrocatalytic studies further show that AONP-PANI-SWCNT modified GCE was stable with only a small current decrease between the I st and 20th scan in both lindane and ED. The fabricated sensor proved superior towards the detection of lindane as compared with literature reports yielding a low detection limit of2.01 nM in the [lindane] range of Oto 18.8 nM. The sensor also demonstrated good electrochemical properties toward Endosulfan (EDS) detection with a limit of detection (LoD) of 5.22 μM in the [EDS] range of 32.3 to 77.6 μM . CV and continuous aperommetry (CA) experiments were conducted to investigate the selectivity of the fabricated sensor. The results obtained indicated that the sensor is highly selective towards the detection of both lindane and endosulphan in the presence of various organic and inorganic interfering species. Real sample analysis was conducted on river water and tap water samples, the average recoveries were calculated and are indicative of the potential practical application for the proposed sensor.

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