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In order to design and optimise sonochemical reactors it is important to study the impact of liquid level, or path length, on the standing wave phenomena and the influence this has on temperature increase and OH radical rate of production. In this work, an ultrasonic tower type reactor operating at 70 kHz is investigated with results from variations to liquid levels reported. Calorimetry data was obtained using a modified reactor set up with temperature change monitored at selected points within the chamber. OH radical rate of formation was shown via chemical dosimetry, following the conversion of terephthalic acid (TA) to 2-hydroxyterephthalic acid (HTA). The results obtained have shown that changes in solution depth of a few millimetres significantly impacts on the interaction of the propagated and reflected waveforms with the results of calorific measurements and HTA rates of formation varying by 90% (750 J) and 88% (80 mmol dm(-3) min(-1)) between the operational extremes over the studied depth range.

The rationale for selection of waste cellulose source and method for its degradation, such as ultrasound, aeration and coupled energy, is examined. Consideration is given to the availability of waste material for the conservation of global resources, pollution effects from energy forms and efficiency of energy transfer. Availability of the sources and possible ways of converting them to fuels, processes involved in its production and the possible effects on the environment are discussed. Manufactured cellulose and waste paper are used as the source for these experiments and the rationale behind their use in the environment is analysed. An ultrasound reactor that operates at 80 W and 38 kHz was used in breaking down the samples to produce glucose and other chemical species. One of the routes being explored is the further conversion of these molecules into fuel (alcohol).

A monitoring system using the collection technique of electrostatic precipitation on to a piezoelectric sensing element is examined. The transduction mechanism is the change in the resonant frequency of the sensing element from its unloaded nominal value of 9 MHz caused by the collected dust. The monitor had the three main design areas (point-to-plane distance, precipitator voltage and electrode-to-dust-inlet distance) optimized at a flow rate of approximately 1 l min −1 . This led to collection efficiencies greater than 97% with crystal mass sensitivity constants in the range 30-130 Hz µg −1 for the aerosol Arizona Road Dust. The total sampling time is limited by overloading of the sensing element by dust. A method of extending the sampling time by using compressed air to clean the sensing element is described.