Electrochemical Characterization and Detection of Lead in Water Using SPCE Modified with BiONPs/PANI

Enyioma C Okpara; Samuel Che Nde; Omolola E Fayemi; Eno E Ebenso

doi:10.3390/nano11051294

Electrochemical Characterization and Detection of Lead in Water Using SPCE Modified with BiONPs/PANI

Nanomaterials (Basel). 2021 May 14;11(5):1294. doi: 10.3390/nano11051294.

Authors

Enyioma C Okpara^{1

2}, Samuel Che Nde³, Omolola E Fayemi^{1

2}, Eno E Ebenso⁴

Affiliations

¹ Department of Chemistry, School of Physical and Chemical Sciences, Faculty of Natural and Agricultural Sciences, North-West University (Mafikeng Campus), Private Bag X2046, Mmabatho 2735, South Africa.
² Material Science Innovation and Modelling (MaSIM) Research Focus Area, Faculty of Natural and Agricultural Sciences, North-West University (Mafikeng Campus), Private Bag X2046, Mmabatho 2735, South Africa.
³ Department of Geography and Environmental Sciences, North-West University, Mafikeng Campus, Mmabatho 2735, South Africa.
⁴ Institute of Nanotechnology and Water Sustainability, College of Science, Engineering and Technology, University of South Africa, Johannesburg 1710, South Africa.

Abstract

The need for constant assessment of river water qualities for both aquatic and other biological survival has emerged a top priority, due to increasing exposure to industrial pollutants. A disposable screen print carbon electrode was modified with a conductive polymer (PANI) and Zn and/or Cu oxides NPs, obtained through bioreduction in citrus peel extracts (lemon and orange), for ultra-sensitive detection of PB²⁺, in the Crocodile River water sample. The synthesized materials were characterized with Fourier-transform infra-red spectroscopy (FTIR), ultra-violet visible spectroscopy (UV-Vis), and scanning electron microscopy (SEM). The SPC-modified electrodes designated as SPCE/LPE/BiONPs/PANI and SPCE/OPE/BiONPs/PANI were characterized using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) and eventually deployed in the electrochemical detection of PB²⁺ in water using square wave voltammetry (SWV) technique. The electrochemical responses of the modified electrodes for both CV and EIS in 0.1 M HCl demonstrated enhanced performance relative to the bare SPCE. A detection and quantification limit of 0.494 ppb and 1.647 were obtained at SPCE/LPE/BiONPs/PANI, respectively, while a detection and quantification limit of 2.79 ppb and 8.91 ppb, respectively, were derived from SPCE/OPE/BiONPs/PANI. The relative standard deviations (RSD) for SPC electrode at a 6.04 µM PB²⁺ analyte concentration was 4.76% and 0.98% at SPCE/LPE/BiONPs/PANI and SPCE/LPE/BiONPs/PANI, respectively. The effect of copper, zinc, iron, cobalt, nickel, and magnesium on the stripping peaks of PB²⁺ at SPCE/OPE/BiONPs/PANI, showed no significant change except for cobalt, with about 17.67% peak current drop. The sensors were assessed for possible determination of PB²⁺ in spiked river water samples. The average percentage recovery and RSD calculated were 94.25% and 3.74% (n = 3) at SPCE/LPE/BiONPs/PANI and, 96.70% and 3.71% (n = 3) at SPCE/OPE/BiONPs/PANI, respectively. Therefore, the fabricated sensor material could be used for environmental assessment of this highly toxic heavy metal in the aquatic system.

Keywords: bi-metallic oxide nanoparticles; citrus peels extracts; electrochemical detection; environmental monitoring; green waste management; heavy metals; screen plate electrodes.

Grants and funding

117709/Thutuka: National research foundation South Africa