No description available.

Thesis (Ph. D.)--Auburn University, 2008. / Abstract. Vita. Includes bibliographical references (p. 132-148).

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

No description available.

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.

No description available.

Abstract The degree of homogeneity and H-bond interaction in blends of low-molecular-mass poly(ethylene glycols) (PEG, Mw = 400, 600, 1000) and poly(vinylpyrrolidone) (PVP, Mw =9×103) prepared in supercritical CO2, ethanol and as physical mixtures were studied by differential scanning calorimetry (DSC), Fourier-transform infrared (FTIR) spectroscopy and dynamic mechanical analysis (DMA) techniques. Homogeneity of samples prepared in supercritical CO2 were greater than physically mixed samples, but slightly less than ethanol-cast samples. PEG–PVP H-bond interaction was higher for ethanol-cast blends when compared to blends prepared in supercritical CO2. This reduced interaction was attributed to a combination of: (1) shielding of PEG–PVP H-bond interactions when CO2 is dissolved in the blend; (2) rapidly reduced PEG and PVP chain mobility upon CO2 venting, delaying rearrangement for optimum PEG–PVP H-bond interaction.

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

The benefits of controlled release drug delivery are important to the pharmaceutical industry. With a controlled release device, local administration of a drug is possible and release profiles can be created that remain within therapeutic limits for prolonged periods. Made from biodegradable and bioerodable polymers, unwanted side effects and the need of return trips for treatment diminish. However, a usable device must be free of organic solvents normally used to dissolve large drug molecules. Many of these solvents are toxic themselves. Therefore, steps must be taken to either remove residual solvent from the final device or limit their use during synthesis. Ideally, it is desirable to remove the organic solvents from the process entirely. Supercritical carbon dioxide (scCO2) has been used as a replacement for these solvents. Carbon dioxide is inexpensive, environmentally acceptable, and safe for use in human consumables. However, many drug molecules have very low solubility in scCO2, resulting in extended polymer impregnation times. An organic co-solvent can be used to increase drug solubility, leading to a more efficient polymer impregnation. Using only a small amount of organic co-solvent, a single phase stream is possible that results in significantly increased solubility. This meets the original task of limiting organic solvents in the process and increases efficiency over scCO2 alone. This study uses supercritical carbon dioxide with ethanol as a co-solvent. Ethanol increases the solubility of β-estradiol in scCO2 for impregnation into the glassy polymer polyvinylpyrrolidone (PVPP). Experimental conditions cover a range of temperatures from 40 °C to 50 °C and pressure up to 2500 psi. The effect of polymer swelling time on the sorption process is also studied. A dual mode sorption model describes the sorption of drug into the glassy polymer, and a plug flow and stirred tank compartmental model predicts breakthrough profiles. The determined sorption parameters allow analysis of polymer conformation and suggest optimum impregnation conditions.

Thesis (Ph. D.)--University of Texas at Austin, 2000. / Vita. Includes bibliographical references (leaves 237-250). Available also in a digital version from Dissertation Abstracts.