Following the successful conclusion of Kgotla Katlego Masibi’s first research report into “Electrochemical properties of carbon nanotubes/PANI/metal oxide nanoparticle nanocomposites towards electrocatalysis of some organochlorine pesticides”, Kgotla is hard at work on a second paper after graduating with his MSc degree last year.
The study was supervised by Prof Eno Ebenso from the subject group Chemistry and the Material Science Innovation and Modelling (MaSIM) research focus area at the North-West University’s (NWU’s) Mahikeng Campus. It was co-supervised by Dr AS Adekunle, a former postdoctoral fellow and Dr OE Fayemi, a senior lecturer at the Faculty of Natural and Agricultural Sciences.
According to Prof Ebenso, this work describes the chemical synthesis of antimony oxide nanoparticles (AONPs), polyaniline (PANI), acid functionalised single-walled carbon nanotubes (fSWCNTs) and the nanocomposite (AONP-PANI-SWCNT) as composite material for the trace detection of some organochlorine pesticides namely 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).
The drop-cast method was used to modify the glassy carbon electrode (GCE) with the synthesised nanomaterials. The 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.
The AONP-PANI-SWCNT modified GCE exhibited faster electron transport properties as well as enhanced catalytic current response compared to bare-GCE, GCE-AONPs, GCE-PANI, and GCE-SWCNT. Electrocatalytic studies further show that AONP-PANI-SWCNT modified GCE was stable with only a small current decrease between the 1st and 20th scan in both lindane and EDS.
The study concluded that: “the fabricated sensor proved superior towards the detection of lindane as compared with literature reports yielding a low detection limit of 2.01 nM in the [lindane] range of 0 to 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. Cyclic Voltammetry (CV) and continuous amperommetry (CA) experiments were conducted to investigate the selectivity of the fabricated sensor”.
The results indicated that the sensor is highly selective towards the detection of lindane and endosulphan in the presence of various organic and inorganic interfering species. Real sample analysis was conducted on river and tap water samples, the average recoveries were calculated and are indicative of the potential practical application for the proposed sensor.
Part of this work has already been published in Frontiers in Chemistry and is available here: https://www.frontiersin.org/articles/10.3389/fchem.2018.00423/full
Prof Eno Ebenso.
