Abstract
M.Tech. (Chemistry)
The main aim of this study was to develop electrochemical sensors based on modification
of glassy carbon electrode of simultaneous detection for selected trace metals in surface
water matrices. Trace metals such as Hg, Tl and Cd are extremely harmful pollutants in
different environments due to their toxicity and even in trace amounts they pose a serious
risk to human health effects. Therefore, it is important to control and monitor their
concentrations in surface water systems as they tend to affect the quality of water.
Electrochemical sensors were developed and optimized for determination of Cd, Cu, Hg,
Tl and Zn in environmental matrices.
For determination of Hg and Tl, rapid, simple and sensitive square wave anodic
stripping voltammetric (SWASV) technique based on glassy carbon electrode modified
with tin oxide nanoparticles@ multiwalled carbon nanotubes was developed. Under
optimized condition, the limit of detection and quantification ranged from 0.9−1.2 ng L−1
and 3.3-4.0 ng L−1, respectively. The inter-day (n=10) and intra-day (n=7) precisions
expressed in relative standard deviations at 50 μg L−1 of Hg(II) and Tl(I) ranged from 2.1-
3.5% and 3.0-4.3%, respectively. The GCE/SnO2@MWCNTs was applied for the
determination of the target trace elements in thirteen surface water samples. The accuracy
of analytical results obtained using the developed electrochemical sensor was comparable
to those obtained by the ICP-MS.
The second electrochemical sensor was based on the fabrication and application of a
glassy carbon electrode with reduced graphene Oxide@MnO2 nanocomposite
(rGO@MnO2) for simultaneous quantification of Zn, Cd and Cu ions in surface water. The
rGO@MnO2 characterized by transmission electron microscopy (TEM) and dispersive xray
spectroscopy (EDS). The electrochemical behaviour of rGO@MnO2/GCE
nanocomposite was measured by cyclic voltammetry (CV) and differential pulse anodic
stripping voltammetry (DPASV). The electrochemical studies revealed that the
rGO@MnO2/GCE dramatically increased the current response against the Zn, Cd and Cd,
due to the synergic effect of MnO2 and rGO. Under optimum conditions, the modified
electrode portrayed sensitivity and relatively high precision for simultaneous determination
of Zn, Cd and Cu. The limits of detection and quantification were up to 9.3-15.1 ng L−1
and 31-50.3 ng L−1, respectively. The results showed that rGO@MnO2 can be successfully
used as electrode modifier for the determination of trace metals in water samples...