Abstract
The selectivity improvement of Electrochemically reduced Graphene Oxide–Multiwalled Carbon Nanotubes–L-cysteine (ErGO–MWNTs–L-cys) nanocomposite modified Glassy Carbon Electrode (GCE) using drop casting method for electrochemical detection of lead (Pb2+) ions was investigated. Initially, the graphene oxide–Multiwalled Carbon Nanotubes–L-cysteine (GO–MWNTs–L-cys) nanocomposite was synthesized by a facile and cost-effective method at room temperature. The as-prepared, GO–MWNTs–L-cys exhibited good stable aqueous dispersions due to high hydrophilic nature of GO components which led to inhibiting the hydrophobicity of MWNTs. Then, the electrochemical conductivity of ErGO–MWNTs–L-cys nanocomposite modified GCE (ErGO–MWNTs–L-cys/GCE) was improved by the direct electrochemical reduction of GO–MWNTs–L-cys nanocomposite. The GO–MWNTs–L-cys nanocomposites and its individual components were characterized by Attenuated Total Reflection Infrared (ATR-IR), Raman spectroscopy, Atomic Force Microscopy and X-ray diffraction (XRD). The synergistic effect of ErGO–MWNTs–L-cys nanocomposite was confirmed by Cyclic Voltammetry (CV) measurements in [Fe(CN)6]3-/4- redox. Experimental parameters, such as pH, accumulation time and electrochemical reduction degrees, were optimized. Under optimal conditions, the electrochemical performance of modified electrodes towards Pb2+ ions was examined and it exhibited appreciable improvement at the ErGO–MWNTs–L-cys/GCE. In terms of applications, Differential Pulse Anodic Stripping Voltammetry (DPASV) was employed for the determination of Pb2+ ions on ErGO–MWNTs–L-cys/GCE. The calibration plots between anodic current and Pb2+ ions exhibited linear relationship in the range of 0.2–40 μgL-1 with the detection limit calculated to be 0.1 μgL-1 (S/N=3). Finally, the ErGO–MWNTs–L-cys/GCE showed satisfied selectivity and stable results, and the Relative Standard Deviation (RSD) was calculated to be (RSD=2.15%).
Highlights
Over the recent decade, the Heavy Metal Ions (HMIs) have been noticeably diffused into the environment from industrial activities such as electroplating, batteries, and geochemical mechanisms (Tinsley, 2004; Liu et al, 2011; Tiwari et al, 2011; Tongesayi et al, 2013; Adarakatti et al, 2017)
We aimed to study the effect of L-cysteine on the novel nanocomposite of three-dimensional graphene oxide/carbon nanotubes hybrid to improve its selectivity toward the detection of Pb2+ ions in aqueous media
This absorption band is totally absent in the MWNTs spectra, whereas it appears again in graphene oxide (GO)–MWNTs and GO–MWNTs–L-cys spectra, with relative decrease in its magnitude, respectively, due to the non-covalent reaction in the GO–MWNTs hybrid and the reduction process by L-cysteine
Summary
The Heavy Metal Ions (HMIs) have been noticeably diffused into the environment from industrial activities such as electroplating, batteries, and geochemical mechanisms (Tinsley, 2004; Liu et al, 2011; Tiwari et al, 2011; Tongesayi et al, 2013; Adarakatti et al, 2017). There have been many sensitive and selective metal ion detection techniques used for detecting heavy metal ions, such as inductively coupled plasma atomic emission spectrometry, inductively coupled plasma mass spectrometry, atomic absorption spectrometry, atomic fluorescence spectrometry, surface enhanced Raman spectrometry, and electrochemical analysis technology (Grasso et al, 2009; Sanchez-Rodas et al, 2010; Koelmel and Amarasiriwardena, 2012; Siraj and Kitte, 2013; Massadeh et al, 2016; Lu et al, 2018). Among the different electrochemical methods anodic stripping voltammetry (ASV) is considered the most suitable method for tracing metal analysis due to its short analysis time, high sensitivity, good selectivity, easy operation, etc. (de Souza et al, 2015)
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