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Thesis (Ph.D.)--University of Melbourne, School of Chemistry, 1999. / Typescript (photocopy). Includes bibliographical references.

The current paper recycling processes are surveyed pointing out the major stages and the variety of chemical/mechanical treatments the fibres undergo. The reduction or replacement of chemical/mechanical treatments presents possible advantages in prolonging fibre life. The results from recycled office waste which has been treated with ultrasound show a change in the particle size distribution of toner particles - making these particles easier to remove using established flotation techniques. Particle size distributions were measured using image analysis on thin (20gsm) paper handsheets. To establish the affect of sonication on fibres, a variety of virgin fibres were obtained from UK Paper, Sittingbourne. Results from virgin fibres which have been treated using ultrasound indicate an absence of cutting compared to conventional techniques. Fibres were found to have the same average length (0.6mm) after ultrasound treatment as the control sample, refined fibres were reduced to approximately 0.3 mm in length. Freeness decreased in both virgin sonicated and refined sonicated samples. The decrease in freeness was accompanied by an increase in the strength properties of both categories of fibres. Experiments with a prepared office waste furnish showed that ultrasonic treatment could decrease the size distribution of fused toner particles. The control sample had an average size of 80.9 um, after 1 minute sonication this was decreased to 54.9) um, decreasing further to 46.8)um after 2 minutes sonication. After demonstrating that ultrasound could decrease the particle distribution of the prepared office waste a more realistic and variable furnish was used. The experiments were conducted at room temperature, 50°C and 75°C. These temperatures were chosen to study the behaviour of fused toners as it approaches and exceeds its glass transition point, essentially the melting point of an amorphous polymer. It was found that the toner is easier to remove as the glass transition temperature is approached. Ultrasound is effective in breaking up large toner particles and detaching particles smaller than 25 microns in diameter.

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This thesis reports the development of sonoelectrochemistry as a technique for sample analysis. Complementary modelling gives an insight into the mass transport and electrode reaction mechanisms. Separate studies were conducted as follows: - Initially an copper(II) acetate buffer system was used as its speciation can be determined. In order to establish under which conditions analysis could be conducted the effect of speciation was examined. These were applied to the Anodic Stripping Voltammetry (ASV) determination of copper in the acetate solution and to facilitate the use of a traditionally inhospitable electrochemical medium: real ale with minimal pre-treatment. Both gave detection limits of the range (1-100) μg L^-1 and in quantitative agreement with Atomic Absorption Spectroscopy. - The effect of acoustic streaming under mild insonation was studied by modelling Square Wave Voltammetry (SWV) of ASV and was found, when compared to experiment, to be the dominating factor. When the latter is strongly present two distinct mass.transport regimes were identified. Studies of chemical and electrochemical processes suggested that the acoustic streaming model fails under more extreme conditions. - SWV voltammetry was modelled for reversible electrochemical reactions leading to a refinement of existing analytical theory and the ASV modelling extended to account for surface morphology and finite electrode kinetics. Droplets on an electrode surface subjected to a potential sweep give rise to voltammetric traces attributed to charge insertion. Three mechanisms for this are proposed: (i) charge injection at the droplets surface, (ii) charge injection at the three phase boundary and (iii) the droplet is saturated with counter ions and electron transfer occurs at the electrode surface. These are solved numerically and incorporate Regular Solution Theory to account for non-ideal interactions. Comparing with experimental data an approximate model identified the processes occurring for small droplets. A Marangoni-type convection is suggested for larger droplets.

Ultrasonic descalers are used in dentistry to remove calculus and other contaminants from teeth. One mechanism which may assist in the cleaning is cavitation generated in cooling water around the descaler. The spatial distribution of cavitation around three designs of descaler tips and under three load conditions has been observed using sonochemiluminescence from a luminol solution and compared with the vibratory motion of the tips in a water bath, characterised by scanning laser vibrometry. The type of cavitation was confirmed by acoustic emission analysed by a ‘Cavimeter’ supplied by NPL. Surface profilometry and SEM of eroded hydroxyapatite pellets was performed to quantitatively study the erosion caused by a descaler tip in both contact and non-contact modes. Densitometry was used to study the erosion of black ink from a glass microscope slide, and determined that under the majority of conditions, no erosion was demonstrated via cavitation, by descalers operating in non-contact mode, although significant erosion was demonstrated with the tip in contact with the slide.

Ultrasonic instruments are used with the aid of an irrigant such as NaOCl in endodontic treatments to remove dentin debris and calculus from infected root canals. This cleaning process may be assisted by various factors, such as acoustic streaming, and the production of radicals and microjets from the collapse of transient cavitation bubbles. The aim of this project is to understand the principal factors affecting the performance of a number of different endosonic files in order to correlate to their cleaning efficiencies. Characterisation includes detecting transient cavitation activity, mapping the areas of cavitation, assessing the file vibration movements and the streaming effects produced by the files. Experiments to assess the cleaning efficiencies of the files include: emulsification, dye removal with a dental irrigant, ink and hydroxyapatite paste removal from model systems designed to mimic the structure of a tooth. The results show that there is a correlation between the sonochemical output and the cleaning efficiencies, and this brings in further study on the possible factors that may affect the production of transient cavitation and the vibration profiles of the endosonic files. Lastly, a series of computational simulation of the acoustic pressure fields from different endosonic files were performed. Correlations of the simulated and experimental results showed the difference in ultrasonic output of the endosonic files is strongly related to their design. This work provides the basis and techniques necessary to perform a comprehensive study on the design of the endosonic files in order to enhance and optimise their cleaning efficiencies during clinical use and to inform future endodontic practice.

Dissertation (Ph. D.)--University of Akron, Dept. of Chemical Engineering, 2005. / "August, 2005." Title from electronic dissertation title page (viewed 12/27/2005) Advisor, H. Michael Cheung; Committee members, J. Richard Elliott, Stephanie T. Lopina, A. Dhinojwala, Avraam I. Isayev; Department Chair, Steven S. Chuang; Dean of the College, George K. Haritos; Dean of the Graduate School, George R. Newkome. Includes bibliographical references.