The objective of this research was to design a pilot scale continuous supercritical fluid extraction (SFE) system for the treatment of drill cuttings.The design includes: • A Piping and instrumentation diagram (P&ID) • A control philosophy • An operation manual, and • A HAZOP analysis The pilot scale SFE system was designed using a HAZOP-inspired framework, which resulted in the inclusion of risk reducing measures. This design approach was appropriate for the design of a novel technology, as risk reduction was made the inherent priority throughout the process. No major changes were made to the design during the professionally conducted safety analysis (HAZOP), thus the design is considered to be well positioned to operate safely. Recommended, non-critical future design improvements include: • Separation of the process control from the safety control systems • Continuous reduction of “human factors”, and • Review of all changes to the design before implementation / Natural Science and Engineering Research Council of Canada; M-I SWACO, a Schlumberger Company

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The use and supply of various organic solvents for analytical chemistry is coming under scrutiny due to their environmental impact. International legislation now prevents the supply of "ozone depleting" solvents for laboratory purposes. Consequently alternative analytical methods to those which had previously relied upon the use of a range of organic solvents need to be developed. Supercritical fluids exhibit some properties associated with gases and liquids, and in particular their solvating characteristics are equivalent to a wide range of conventional organic solvents. Environmentally benign carbon dioxide in its supercritical fluid state can be utilised to imitate the solvating power of a range of organic solvents from non polar pentane through to more polar pyridine. There are many reports detailing the use of supercritical fluid extraction for the isolation of target compounds from a very wide range of solid matrices. The objective of these studies was to develop direct liquid supercritical fluid extraction procedures using carbon dioxide to isolate, concentrate and quantify target analytes from aqueous media. These investigations involved using off-line and on-line supercritical fluid extraction procedures with final analytical detection and quantification being accomplished using a range of chromatographic, spectroscopic and mass spectrometric methods. Within chapters 2 and 3, an alternative infrared method for determining the quantity of oil in process and discharge waters is described. The results of quantification studies involving various oils and hydrocarbons indicate that the custom built supercritical fluid extraction system developed for these investigations directly coupled with an infrared spectrometer provide an alternative method to traditional liquid-liquid extraction procedures that involve the use of ozone depleting and/or toxic organic solvents. Chapter 4 describes how direct aqueous supercritical fluid extraction was used to continuously isolate free testosterone as it was liberated during the enzymic digest of a testosterone-/3-D-glucuronide solution incubated with Helix pomatia glucuronidase. Other studies described within this chapter that also involved the use of direct aqueous supercritical fluid extraction with off-line gas chromatography-mass spectrometry describe procedures for determining trace levels of organophosphate pesticides and polyaromatic hydrocarbons in aqueous samples. The development and use of on-line direct aqueous supercritical fluid extraction coupled with supercritical fluid chromatography-mass spectrometry using atmospheric pressure chemical ionisation for the analysis of phenols at the ppb level is described in Chapter 5. Chapter 6 describes the use of direct aqueous supercritical fluid extraction coupled online with liquid chromatography-mass spectrometry using ammonia chemical ionization for the analysis of three veterinary drugs at the ppb level. Results of off-line and on-line studies involving electrospray tandem mass spectrometry with high pressure liquid chromatography for the analysis of a range of ionophores at the low ppb level following their isolation using direct aqueous supercritical fluid extraction are also presented.

The extraction of pentachlorophenol (PCP) from pressure treated wood wafers with supercritical carbon dioxide has been studied. Experimental data were obtained for the effects of pressure (17.5 - 25.0 MPa), temperature (313 - 353 K), flow rate (1 - 3 ml/min at supercritical conditions), and sample size (0.8 x 10 x 50 mm and 2.2 x 10 x 50 mm) by measuring the effluent concentration versus time. A fundamental model was developed which includes rates of intraparticle diffusion, external film mass transfer, desorption and the initial distribution of PCP between the pore volume (cell lumen) and pore surface (cell wall) of wood wafers. The intraparticle diffusion and external mass transfer rates are combined in terms of an overall mass transfer coefficient derived from the assumption of a parabolic concentration profile of PCP inside the wafer pores. The initial distribution of PCP between cell lumen and cell wall was determined by fitting the mathematical model to dynamic extraction rate data. The desorption rate was very small for all the extraction conditions, and extraction rate increased with the pressure, temperature, and flow rate because the combined mass transfer increased. Similar values of mass transfer coefficient were achieved for two different sample sizes: 0.8 x 10 x 50 mm and 2.2 x 10 x 50 mm. / Graduation date: 1994

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The thesis outlines an investigative study of the supercritical fluid extraction (SFE) of organic natural products from two Meliaceae species. Extractions from ground wood, bark and seeds of the selected species were studied. Qualitative and quantitative studies were performed using a number of techniques. In the qualitative study, both off-line and on-line combination of micro-SFE with capillary gas chromatography (SFE-GC) were performed on the wood and bark of Cedrela toona to show the applicability of the technique in the analysis of semi-volatile components from plant matrices. Results for the on-line and off-line SFE-GC were comparable and indicated that the on-line studies could be used to predict results obtainable from large scale SFE. Dynamic SFE of the limonoid (cedrelone) from the wood of Cedrela toona using pure and modified carbon dioxide was studied on the basis of a theoretically-derived dynamic extraction model. Extracts were collected for different lengths of time in order to investigate the extraction kinetics of this compound. The theoretically-derived model which involved extrapolating data obtained from shorter extraction times was used to estimate the amount of the compound present in the wood. The estimated quantitative results were found to be comparable to exhaustive extractions using liquid hexane as well as methanol-modified carbon dioxide. Further, data from the SFE extractions were fitted into the model to produce a characteristic kinetic curve from which factors controlling the extraction of the specific compound could be predicted. Following the dynamic extraction study, a statistical optimisation strategy was used to propose a model equation for the extraction of cedrelone from the wood of Cedrela toona. As the preliminary step, a screening design utilising a two level, three-factor full factorial analysis was used to study the effects of the variables pressure, temperature and the length of extraction time on the yields of cedrelone from the wood of Cedrela toona. By a statistical analysis of variance (ANOVA) at the 95% confidence level on the preliminary data collected, pressure and temperature were found to be the significant variables influencing the yields of the compound. Finally response surface methodology using the central composite design was used in an attempt to determine the maximum response space for the pressure and temperature effects by plotting a 3-dimensional response surface graph. An ANOVA study at the 99% confidence level was then employed to establish the true model equation for the extraction. / Thesis (M.Sc.)-University of Natal, 1995.

Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1991. / Vita. Abstract. Includes bibliographical references (leaves 167-170). Also available via the Internet.