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Electrochemical detection of organic and inorganic water pollutants using recompressed exfoliated graphite electrodes

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dc.contributor.advisor Prof. B.B. Mamba, Prof. R.W.M. Krause, Prof. S. Sampath, Dr. O.A. Arotiba en_US
dc.contributor.author Ndlovu, Thabile
dc.date.accessioned 2012-11-05T14:21:24Z
dc.date.available 2012-11-05T14:21:24Z
dc.date.issued 2012-11-05
dc.date.submitted 2012
dc.identifier.uri http://hdl.handle.net/10210/8091
dc.description Ph.D. en_US
dc.description.abstract This study explored the possible application of a relatively new electrode called exfoliated graphite electrode (EG electrode) in the electroanalysis of organic and inorganic water pollutants. This study also explored the applicability of this electrode in the removal of heavy metal pollutants in water. The EG material was successfully prepared by intercalating bisulphate ions into graphite flakes (>300 μm) followed by thermal shock at 800°C to obtain an exfoliated graphite. After compressing the EG at high pressure, the obtained circular sheets were used to fabricate electrodes. The electrochemical profiles of EG electrode and glassy carbon electrodes (GCE) were recorded and compared using cyclic voltammetryand square wave voltammetry in the presence of various supporting electrolytes and [Fe(CN)6]3-/4-, [Ru(NH3)6]2+/3+, ferrocene redox probes. In the supporting electrolytes (KCl, H2SO4, NaOH, tetrabutylammoniumtetraflouroborate, phosphate buffers), the potential windows of EG were found, in some cases, to be about 300 mV larger than that of GCE. The diffusion coefficients (cm2s-1) of the redox probes were calculated to be 3.638 x 10-6, 1.213 x 10-6 and 4.411 x 10-6 for [Fe(CN)6]3-/4-, [Ru(NH3)6]2+/3+ and ferrocene, respectively. These values are comparable to those obtained from GCE. Furthermore, EG was modified with various nanomaterials such as poly (propylene imine) dendrimer (PPI), gold nanoparticles, silver nanoparticles, dendrimer–gold nanoparticles composite, cobalt oxide and bismuth. The morphologies of the modified electrodes were studied using scanning electron microscopy and their electrochemical reactivities in the three redox probes were investigated. The current and the reversibility of redox probes were enhanced in the presence of modifiers in different degrees with dendrimer and gold nanoparticles having a favourable edge. The electrochemical determination of o-nitrophenol by square wave voltammetry using a nanocomposite of generation 2 poly(propyleneimine) dendrimer and gold nanoparticles modified GCEand EG electrode were compared. A characteristic reduction peak between -600 mV and -700 mV for o-nitrophenol was observed with enhanced current on both GCE and EG modified electrodes. en_US
dc.language.iso en en_US
dc.subject Exfoliated graphite electrodes en_US
dc.subject Organic water pollutants en_US
dc.subject Inorganic compounds - Environmental aspects
dc.subject Water analysis
dc.subject Electrodes
dc.title Electrochemical detection of organic and inorganic water pollutants using recompressed exfoliated graphite electrodes en_US
dc.type Thesis en_US

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