Bongiwe Silwana

Application of a Bismuth-Silver Nanosensor for the Simultaneous Determination of Pt-Rh and Pd-Rh Complexes

The present work describes the development of an electrochemical sensor for the simultaneous determination of Pd-Rh and Pt-Rh complexes using a bismuth-silver bimetallic nanofilm modified glassy carbon electrode. The electrochemical sensor was prepared by drop-casting bismuth-silver bimetallic nanoparticles on to glassy carbon electrode surfaces. The HRTEM microscopy and UV-Vis spectroscopy results of the bismuth-silver nanoparticles were compared with other work in literature. The developed nanosensor exhibited a linear working range of 0.4 - 1.4 ng/L for Pd-Rh and 0.8-1.2 ng/L for Pt-Rh DMG complexes, respectively. Very low detection limits (S/N = 3) of 0.19 ng/L for Pd (II), 0.2 ng/L Pt (II) and 0.22 ng/L for Rh (III) were obtained and the sensor was successfully applied to environmental samples.

Graphene Oxide–Antimony Nanocomposite Sensor for Analysis of Platinum Group Metals in Roadside Soil Samples

The present study introduced a very sensitive and low-cost analytical procedure based on voltammetry to study platinum group metals in road dust and roadside soil matrices. Cathodic stripping voltammetry in conjunction with a reduced graphene oxideantimony nanocomposite sensor and ICP-MS analysis were used to analyse roadside soil and dust samples. The results were processed to evaluate possible pollution in order to map the distribution of the PGMs along specific roads in the Stellenbosch area, outside Cape Town. The results revealed that within each site under investigation, Pd was more abundant than Pt and Rh using both voltammetric and spectroscopic methods. The AdDPCSV results obtained showed concentrations for Pd(II) ranging between 0.92 – 4.0 ng kg. For Pt (II), the concentrations ranged between 0.84 – 0.99 ng kg–1. For Rh(III), concentrations ranged between 0.42 – 1.21 ng kg. The ICP-MS results showed Pd concentrations ranging between 0.01 – 0.34 μg kg. For Pt the concentrations ranged between 0.004 – 0.07 μg kg–1. For Rh, concentrations ranged between 0.002 – 0.26 μg kg–1. The analysis showed significant levels of all PGMs in soil and dust samples analysed. Metal concentration in dust and soil followed the trend Pd > Pt > Rh using both voltammetric and spectroscopic techniques.

Voltammetric Analysis of Platinum Group Metals Using a Bismuth-Silver Bimetallic Nanoparticles Sensor

National Research Foundation (South Africa) and the CSIR (NRE, Stellenbosch) ,SensorLab, Chemistry Department, University of the Western Cape, Bellville, South Africa

A Sensitive Reduced Graphene Oxide-Antimony Nanofilm Sensor for Simultaneous Determination of PGMs

Electrochemical kinetics of Platinum Group Metals was studied by cyclic voltammetry and the concentration of these metal ions was successfully detected by adsorptive differential pulse cathodic stripping voltammetry using a GCE/rGO-SbNPs sensor. The sensor constructed in this work consisted of a reduced graphene oxide film that was impregnated with antimony nanoparticles. The constructed nanosensor provided an excellent platform for the simultaneous determination of Pd (II), Pt (II) and Rh (III) metal ions. The analytical curve was linear in the concentration range from 0 - 0.40 ng L-1, and 0 - 0.56 ng L-1 for Pd (II)-Rh (III) and Pt (II)-Rh (III), respectively. The detection limits of Pd (II) and Rh (III) were found to be 0.46 ng L-1and 0.55 ng L-1, respectively while for Pt (II) and Rh (III) it was 0.52 ng L-1and 0.48 ng L-1, respectively. The relative standard deviation from 5 measurements for 0.4 ng L-1 Pd (II)-Rh (III) and Pt (II)-Rh (III) by using the GCE/rGO-SbNPs sensor was found to be 6.21% and 3.96%, respectively. Interferences by other metal ions were also studied.