No description available.

No description available.

Aniline was chosen as an atmospheric pollutant which might be monitored using an electrochemical sensor. The effect of pH and of different organic solvents on electrode poisoning was investigated for the analysis of aniline by voltammetry and it was concluded that it was not possible to prevent poisoning of the electrode by the reaction products. The analysis of aniline by flow injection analysis (fia) with DC (constant potential) and pulsed (double pulse) amperometric detection also suffered from electrode poisoning and the latter had a relatively high detection limit. Secondary and tertiary substituted anilines with similar volatilities to aniline at room temperature were examined as suitable alternatives to aniline using voltammetry. Dimethyl-p-toluidine poisoned the electrode to a small extent when analysed by voltammetry. Detection of this compound by fia with pulsed amperometric detection showed improved electrode stability but was not judged suitable for long term monitoring of atmospheric samples of the amine. A satisfactory method for monitoring aniline on line was developed using fia with triple pulse amperometric detection (PAD). The PAD waveform was optimised with respect to a low detection limit and a degree of selectivity towards possible atmospheric interferents for the detection of aniline in dilute aqueous acid at a platinum electrode. A wall jet cell was designed for the analysis of aniline vapour in air which was continuously trapped in dilute acid and periodically injected into a fia system. The cell was not affected by small gas bubbles and was reasonably portable.

No description available.

No description available.

A thesis is presented which reports on an investigation into air quality with an emphasis on the design and development of a numerical model for the transport of gaseous and particulate pollutants in airborne and deposited matter. The reported programme of research was undertaken with the dual aim of; establishing a programme of monitoring in order that ambient concentrations of selected air pollutants, released from various sources proximate to the Dundee area, could be quantified and assessed; and implementing the design, development and verification of a computational prototype model for the simulation of short term air pollutant transport using available Personnal Computer (PC) technology. Four monitoring programmes were successfully undertaken and reported on during the course of research. Three of the monitoring programmes were concerned with the quantification and assessment of ambient concentrations of traffic related pollutants in and around urban areas within the City of Dundee, Scotland. The fourth monitoring programme reports on the quantification and assessment of the potential environmental impact of the Baldovie Municipal Waste Incinerator with regards to the stack emission of the heavy metals, Cadmium (Cd) and Lead (Pb). The findings of the reported studies were found to form original contributions to local knowledge as well as to the field of air quality. Some of the finding have been published in reputable journals (Collett <i>et al</i>, (1 9 9 7 )), (Collett <i>et al</i>, (1 9 9 8 )). Also presented is a detailed report on the design, development and verification of the Short term Atmospheric Pollutant Transport Analysis Model (SAPTAM). The SAPTAM model was developed to simulate short term pollutant dispersal accounting for the effects of atmospheric stability, terrain and secondary transport dynamics, such as, dry deposition, wet deposition and chemical reactions. The model employs a simplified three dimensional Eularian wind field generator (WIFS) coupled to a Lagrangian particle in cell model (PICATS). The PICATS model simulates pollutant dispersion by releasing pseudo particles into a resolved wind field and calculating the consecutive trajectory of each particle over time. The findings of the reported research programme clearly demonstrate that the SAPTAM model, while supporting a low computational overhead and high level of description, is capable of representing pollutant dispersion over a range of scales with an acceptable level of empirical adequacy. The reported work undertaken as part of the development and verification of the SAPTAM model collectively forms an original contribution to knowledge given that the derivation and implementation of the approach on a PC based platform is completely novel.

No description available.

No description available.

No description available.

Current and future pollutant enussion legislation calls for decreased NOx emissions from combustion systems. A review of techniques used for NOx abatement led to the choice of combustor redesign to be the most cost effective method available. This led to the design, construction and development of a combustion system that utilised a Coanda ejector to generate recirculation of the exiting high temperature combustion products to mix with the air supply. Cooling of the burner was integrated into the design through the use of the air and fuel supplies. Computational fluid dynamics was used to model and aid development of the design. The model was used to predict NOx and CO emissions and the fuel-air mixing pattern. This, along with an analysis of experimental results and observations led to an understanding of the burner operation with respect to pollutant emissions and stability. NOx emissions from the Coanda burner were found to be lowest when using a 0.2 mm Coanda gap width, resulting in 16 ppm NOx being emitted at an air to fuel ratio of 1.5. However, the use ofa 0.2 mm Coanda gap width required an air supply pressure of up to 4 bar. The use of a 0.5 mm Coanda gap width enabled burner operation at lower air supply pressures. The resulting NOx emissions were measured as 23 ppm at an air to fuel ratio of 1.I, with a corresponding exit gas temperature of 2200 K. Flue gas recirculation quantity, flame stability, flame stabiliser shape and operational limits proved to be inter-linked in the reduction of NOx emissions. It was found that fuel-air mixing was controlled by the entrainment properties of the Coanda ejector and the flame stabiliser. The average oxygen concentration entering the combustion chamber when using a 0.2 mm and 0.5 mm Coanda gap width was 13.7 % and 16.6 %, respectively. Due to the position of the fuel injector, a fuel rich region formed behind the flame stabiliser. With a suitable flame stabiliser geometry and the use of 'fingers', low NOx combustion and flame stability was achieved near stoichiometric conditions. It was shown that the design of the burner enabled very low pollutant emissions near stoichiometric conditions, resulting in high exit gas temperatures. Conceivable applications of this type of burner could lie in small and intermediate furnaces where low NOx emissions are required. Additionally, very high temperature applications, such as glass furnaces could benefit in both cost and pollutant emissions from such a burner.