This thesis presents experimental work with the primary aim of developing new approaches for the detection and characterisation of nanoparticles via electrochemical methods. The first chapter introduces the fundamental aspects of electrochemistry while the second chapter discusses the need for nanoparticle detection methods and the nonelectrochemical and electrochemical techniques that are currently used in the measurement of nanoparticles. A novel way to quantify silver nanoparticles in aqueous solution is proposed via nanoparticle-electrode impact experiments. In this technique a suitably potentiostatted electrode is immersed in a nanoparticle solution so as to bring about the oxidation or reduction of a single nanoparticle upon its collision with the electrode surface. This “direct” nanoparticle impact technique is then employed to detect laboratory synthesised silver nanoparticles in seawater. It is further shown that this method is capable of sizing silver nanoparticles contained in a commercially available cleaning product. Commercial silver nanoparticles are subsequently monitored via a sticking and stripping technique where homemade gold electrodes fabricated from CDs are immersed in a seawater sample spiked with nanoparticles prior to stripping voltammetry. The reduction of hydrogen peroxide on the surface of silver nanoparticles impacting upon an electrode is also examined. This “indirect” nanoparticle detection method is shown to provide an accurate route to nanoparticle sizing. A Fickian model is subsequently proposed to describe nanoparticle transport to the substrate electrode in both direct and indirect nanoparticle detection techniques. The importance of determining the proportion of nanoparticles which adhere to the electrode surface upon impact is highlighted and the sticking coefficient of a gold nanoparticle at a carbon surface determined. This technique to monitor nanoparticle sticking is optimised by chemical modification of the substrate electrode in order to achieve a “sticky” surface improving the rate of silver nanoparticle sticking. Finally, the nanoparticle collision method is shown to be applicable to C₆₀ nanoparticles where their detection and sizing is achieved in non-aqueous conditions. The methods developed in this thesis make a significant contribution to the promising application of electrochemical techniques in the detection and characterisation of single nanoparticles.

Following several reports in the past few years about compositional changes on palladium used as a cathode in heavy water electrolysis, the purpose of this research project was to reproduce this results. Two experiments were performed using two cells connected in series, an experimental cell and a control cell. Both experiments used platinum anodes, the experimental cell had a palladium cathode and the control cell had a platinum cathode. The electrolyte was D20 with H2S04. Radiation was monitored during both experiments. Also temperature and voltage were recorded for both experiments, to allow statements about excess heat of the experimental cell in comparison to the control cell. Both experiments had problems with unequal electrolyte loss, so that no statements about excess heat could be made. No significant radiation was detected in either experiment. Also no compositional changes on the palladium cathodes after electrolysis in both experiments could be detected. Impurities in grain-shaped defects on the palladium cathode before the experiment were found in either experiment. These impurities were Si, Ca, 0, and sometimes also Mg, Na and Fe. Localized findings of Au and Pt, in a distance of 1-2μm to each other, were made on the palladium cathode from the second experiment before electrolysis. Spot, grain-shaped and longitudinal defects were found on the original palladium foil used for the cathodes in either experiment No evidence for fusion, or any other nuclear reaction in the crystal lattice of palladium, used as cathode in heavy water electrolysis, was observed.

Graduation date: 1991

Thesis (Ph. D.)--Ohio State University, 2004. / Title from first page of PDF file. Document formatted into pages; contains xvi, 149 p.; also includes graphics (some col.). Includes abstract and vita. Advisor: Sheikh Akbar, Dept. of Materials Science and Engineering. Includes bibliographical references (p. 138-149).

Nitrogen compounds, such as aqueous ammonia, are a widespread problem in the wastewater industry as they are toxic to numerous aquatic life, cause eutrophication, and contribute to various environmental concerns. Environment Canada has mandated new wastewater regulations, limiting un-ionized ammonia discharge to 1.25 mg/L, expressed as nitrogen. This study provides insight into methods for removing nitrogen compounds, specifically aqueous ammonia, from wastewater. Two wastewater treatment technologies were compared: Ultra Violet light and an electrochemical process. These treatments were evaluated individually, as well as in combination, to determine potential synergistic effects.

No description available.

<p>A comparative study of electrolysers using different anodic materials for the electrolysis of brine (sodium chloride) for the production of sodium hypochlorite as a source of available chlorine for disinfection of rural water supplies has been undertaken. The electrolyser design used was tubular in form, having two chambers i.e. anode inside and cathode outside, separated by a tubular inorganic ceramic membrane. The anode was made of titanium rod coated with a thin layer of platinum and a further coat of metal oxide. The cathode was made of stainless steel wire. An assessment of these electrolysers was undertaken by studying the effects of some variable parameters i.e.current, voltage and sodium chloride concentration. The cobalt electrolyser has been shown to be superior as compared to the ruthenium dioxide and manganese dioxide electrolysers in terms of hypochlorite generation. Analysis of hydroxyl radicals was undertaken since there were claims that these are produced during brine electrolysis. Hydroxyl radical analysis was not successful, since sodium hypochlorite and hypochlorous acid interfere using the analytical method described in this study.</p>

<p>This study has shown that OH˙ radicals can be generated in an Fe/O2 cell from the electrode products via Fenton&rsquo / s reaction and used for water disinfection. The cell system in which the experiments were carried out was open and undivided and contained two electrodes with iron (Fe) as the anode and oxygen (O2) gas diffusion electrode. Typically, 100 ml of Na2SO4.10H2O (0.5M) solution was used as a background electrolyte. OH˙ radicals were produced in-situ in an acidic solution aqueous by oxidation of iron (II), formed by dissolving of the anode, with hydrogen peroxide (H2O2). The H2O2 was electrogenerated by reduction of oxygen using porous reticulated vitreous carbon (RVC) as a catalyst.</p>

Thesis (M.S.)--West Virginia University, 2008. / Title from document title page. Document formatted into pages; contains x, 67 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 63-67).

Mémoire (M.Sc.A.)-- Université du Québec à Chicoutimi, 1988. / Document électronique également accessible en format PDF. CaQCU