Abstract
Abstract : In South Africa, industrial development and mining sustain the economy. Unfortunately, the effluents from these industries introduce heavy metal pollutants such as lead (Pb2+) into the environmental water. Pb2+ is widely recognized as one of the highly toxic and non-biodegradable metal that poses serious health problems and even death. This study presents a method of heavy metal analysis by modifying glassy carbon electrode (GCE) with gold nanoparticles (AuNPs) and generation 2 (G2) poly(propyleneimine) dendrimer (PPI) to provide a highly sensitive electrochemical sensor for the determination of Pb2+ ions in water using square wave anodic stripping voltammetry (SWASV). The co-deposition of PPI and AuNPs on the surface of GCE was confirmed by atomic force microscopy (AFM). Voltammetric probing showed that the GCE-PPI/AuNPs platform exhibited reversible electrochemistry and conductivity in [Fe(CN)6]3 −/4 – redox probe. The electroactive surface area of the bare GCE, GCE-PPI, GCE-AuNPs and GCE-PPI/AuNPs were also estimated in order to illustrate that the prepared PPI/AuNPs nanocomposite could improve the surface area and conductivity of the GCE and was found to be 8.17 mm2 for bare GCE, 10.84 mm2 for GCE-PPI, 11.03 mm2 for GCE-AuNPs and 11.13 mm2 for GCE-PPI/AuNPs. The electroactive surface area of GCE-PPI/AuNPs modified electrode increased by approximately 36.23% as compared to bare GCE, which provided an effective evidence for the superior conductivity of PPI/AuNPs as expected. The effect of different electrochemical parameters on the sensitivity of the sensor for the Pb2+ detection was also scrutinized, including supporting electrolyte (HNO3), deposition potential (-800 mV) and deposition time (150s). The sensor was applied in the detection of different standard concentrations of Pb2+, linear range of (1 ppb-100 ppb) with detection limit of 0.96 ppb. The GCE-PPI/AuNPs sensor was then applied to detect Pb2+ in tap water whose results were validated with ICP-OES.
M.Sc. (Nanoscience)