Hydration and functional group effects of organic solutes in water at high temperatures and pressures

dc.contributor.advisorTremaine, Peter
dc.contributor.authorBulemela, Ephraim
dc.date.accessioned2020-08-24T15:47:49Z
dc.date.available2020-08-24T15:47:49Z
dc.date.copyright2006
dc.degree.departmentDepartment of Chemistry and Biochemistryen_US
dc.degree.grantorUniversity of Guelphen_US
dc.degree.nameDoctor of Philosophyen_US
dc.description.abstractDensities and equilibrium constants have been measured for aqueous solutions of amines, alkanolamines and hydroxy-carboxylic acids at temperatures up to 350°C and pressures up to 20 MPa. Densities were measured using a high-temperature and high-pressure vibrating tube densimeter. Apparent molar volumes, V [straight phi] were calculated for each solute from the experimental densities and extrapolated to give standard partial molar volumes, <math> <f> <rm>V0<inf>2</inf></rm></f> </math>. The experimental values have been corrected for hydrolysis or dissociation, where necessary, and the variation of the volumes with temperature and structure of solutes were discussed. With the exception of glycolic acid, all the other organic nonelectrolytes studied showed normal behavior, namely <math> <f> <rm>V0<inf>2</inf></rm></f> </math> becomes increasingly positive as the critical point of water is approached. The equilibrium constants were measured using UV-visible spectroscopy and thermally-stable colorimetric pH indicators up to the temperature, t = 350°C and pressure up to 20 MPa. A specialised flow through cell was built for use in conjunction with UV-visible spectroscopic techniques for equilibrium constant measurements. The flow cell consists of a platinum liner and titanium casing and was tested for use in the temperature range up to 350°C and pressure up to 20 MPa. A new functional group additivity scheme for standard partial molar volumes of aqueous organic solutes has been developed using the high-temperature experimental data from this work and the limited available data from the literature. The group additivity contribution of the -CH3, >CH2, -CH, -NH2, >NH, >N-, -OH and -COOH functional groups were obtained as a function of temperature and pressure. The additivity method utilizes the features of the equation of state by O'Connell 'et al'. (1996) and is similar to that of Yezdimer 'et al'. (2000), used over a wide range of temperature and pressure with emphasis on the near-critical region. The new group additivity model developed in this work is more accurate than the existing group additivity models for predicting standard partial molar volumes up to at least 325°C.en_US
dc.identifier.urihttps://hdl.handle.net/10214/20143
dc.language.isoen
dc.publisherUniversity of Guelphen_US
dc.rights.licenseAll items in the Atrium are protected by copyright with all rights reserved unless otherwise indicated.
dc.subjectOrganic solutesen_US
dc.subjectWateren_US
dc.subjectHigh temperaturesen_US
dc.subjectPressuresen_US
dc.subjectHydrationen_US
dc.titleHydration and functional group effects of organic solutes in water at high temperatures and pressuresen_US
dc.typeThesisen_US

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