Abstract
Heavy metals, such as Pb2+, Cd2+, and Zn2+, cause major public-health concerns due to their high stability and bio-accumulation. These heavy metals affect several human organs even at very low concentrations. Accordingly, developing simple, robust and highly sensitive analytical methods for assessing environmental pollutants in soil, water, and air samples to improve the quality of environment and human life is very important. Graphene is an excellent nanomaterial for electrochemistry owing to its good electrical conductivity, low cost, excellent mechanical properties, and high specific surface area. To date, much research has been focused on their development for attractive applications in electroanalytical chemistry as a unique electrode material for manifolds. Moreover, chemical modification of graphene could further improve its electrochemical performance. The resultant activated graphene has a unique structure that makes it attractive as a potential material for the electrochemical determination of trace metal ions. In this work, we developed a facile method for the preparation of a new and enhanced sensing platform based on bismuth and activated graphene. The activated graphene was prepared through chemical activation of graphene oxide with KOH to create nanopores. The surface morphology of the bismuth-activated graphene nanocomposite film modified electrode was investigated by using scanning electron microscopy and transmission electron microscopy. The electrochemical properties of the nanocomposite electrode were evaluated to examine the effects of experimental variables, such as deposition potential, deposition time, bismuth concentration, and stirring speed during pre-concentration, on the determination of trace metal ions. The bismuth-activated graphene nanocomposite electrode was applied for the simultaneous determination of trace zinc, cadmium, and lead by differential pulse anodic stripping voltammetry. The composite film integrates the unique properties of activated graphene and the advantages of bismuth electrodes, leading to enhanced sensitivity towards trace metal ions, especially zinc. The appearance of a zinc stripping peak reveals its superior sensitivity as compared to previous bismuth electrodes. The bismuth-activated graphene nanocomposite was also used as an electrode material for the sensitive determination of metal ions in a real sample. The limits of detection achieved are much lower than the guideline for drinking water quality provided by the World Health Organization. Thus, the proposed method facilitates the monitoring of trace heavy metals and can be expanded to detect other environmental pollutants.
Published Version
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