Synthesis of hydrazine by the fixation process

A critical review of the literature concerning organic derivatives of hydrazine, the ammonia-chlorine reaction and the electrolytic formation of hydrazine has been carried out. Apparatus was constructed to study the electrolysis of liquid ammonia, the formation of chloramine and the fixation of chloramine with a ketone to form an isohydrazone. In the latter case the reaction was carried out in a 3" diameter stirred tank and also in a 1" diameter, 2' high column reactor where the liquid phase was continuously recirculated. Two methods of analysis of azines and isohydrazones in a ketone solution have been developed. One is a colorimetric technique using p-dimethylaminobenzaldehyde and the other involves the hydrolysis of the organic derivative to hydrazine sulphate. Hydrazine was detected in low concentration in some of the electrolytic experiments carried out but it was concluded that this method did not show sufficient promise to warrant further investigation. The gas phase formation of chloramine and acetone isohydrazone has also been studied but in this system difficulties were encountered with the chlorine jet blocking with ammonium chloride. The formation of isohydrazones in a stirred tank reactor has been investigated in some detail and the effect of several parameters was determined. The yield was found to be extremely sensitive to chlorine concentration and in order to obtain yields of more than 90 per cent, the molar concentration of chlorine in the gas phase had to be of the order of 5 per cent. An optimum temperature in the region of 0°C was also detected. These results disagree with those quoted in previous studies but extensive experimental work has confirmed the information presented in this thesis. It has also been shown that at high yields the chloramine formation reaction took place in the gas phase.

Determination of vertical and horizontal pathways of injected fresh wastewater into a deep saline aquifer (Florida, USA) using natural chemical tracers

Two deep-well injection sites in south Florida, USA, inject an average of 430 million liters per day (MLD) of treated domestic fresh wastewater into a deep saline aquifer 900 m below land surface. Elevated levels of NH3 (highest concentration 939 µmol) in the overlying aquifer above ambient concentrations (concentration less than 30 µmol) were evidence of the upward migration of injected fluids. Three pathways were distinguished based on ammonium, chloride and bromide ratios, and temperature. At the South District Wastewater Treatment Plant, the tracer ratios showed that the injectate remained chemically distinct as it migrated upwards through rapid vertical pathways via density-driven buoyancy. The warmer injectate (mean 28°C) retained the temperature signal as it vertically migrated upwards; however, the temperature signal did not persist as the injectate moved horizontally into the overlying aquifers. Once introduced, the injectate moved slowly horizontally through the aquifer and mixed with ambient water. At the North District Wastewater Treatment Plant, data provide strong evidence of a one-time pulse of injectate into the overlying aquifers due to improper well construction. No evidence of rapid vertical pathways was observed at the North District Wastewater Treatment Plant.

Encapsulation of phase change materials using rice-husk-char

This paper explored a new approach to prepare phase change microcapsules using carbon-based particles via Pickering emulsions for energy storage applications. Rice-husk-char, a by-product in biofuel production, containing 53.58 wt% of carbon was used as a model carbon-based material to encapsulate hexadecane. As a model phase change material, hexadecane was emulsified in aqueous suspensions of rice-husk-char nanoparticles. Water soluble polymers poly(diallyldimethyl-ammonium chloride) and poly(sodium styrene sulfonate) were used to fix the rice-husk-char nanoparticles on the emulsion droplets through layer-by-layer assembly to enhance the structural stability of the microcapsules. The microcapsules formed are composed of a thin shell encompassing a large core consisting of hexadecane. Thermal gravimetrical and differential scanning calorimeter analyses showed the phase change enthalpy of 80.9 kJ kg−1 or 120.0 MJ m−3. Design criteria of phase change microcapsules and preparation considerations were discussed in terms of desired applications. This work demonstrated possible utilisations of biomass-originated carbon-based material for thermal energy recovery and storage applications, which can be a new route of carbon capture and utilisation.

Enhancing non-refractory aerosol apportionment from an urban industrial site through receptor modelling of complete high time-resolution aerosol mass spectra

Receptor modelling was performed on quadrupole unit mass resolution aerosol mass spectrometer (Q-AMS) sub-micron particulate matter (PM) chemical speciation measurements from Windsor, Ontario, an industrial city situated across the Detroit River from Detroit, Michigan. Aerosol and trace gas measurements were collected on board Environment Canada’s CRUISER mobile laboratory. Positive matrix factorization (PMF) was performed on the AMS full particle-phase mass spectrum (PMFFull MS) encompassing both organic and inorganic components. This approach was compared to the more common method of analysing only the organic mass spectra (PMFOrg MS). PMF of the full mass spectrum revealed that variability in the non-refractory sub-micron aerosol concentration and composition was best explained by six factors: an amine-containing factor (Amine); an ammonium sulphate and oxygenated organic aerosol containing factor (Sulphate-OA); an ammonium nitrate and oxygenated organic aerosol containing factor (Nitrate-OA); an ammonium chloride containing factor (Chloride); a hydrocarbon like organic aerosol (HOA) factor; and a moderately oxygenated organic aerosol factor (OOA). PMF of the organic mass spectrum revealed three factors of similar composition to some of those revealed through PMFFull MS: Amine, HOA and OOA. Including both the inorganic and organic mass proved to be a beneficial approach to analysing the unit mass resolution AMS data for several reasons. First, it provided a method for potentially calculating more accurate sub-micron PM mass concentrations, particularly when unusual factors are present, in this case, an Amine factor. As this method does not rely on a priori knowledge of chemical species, it circumvents the need for any adjustments to the traditional AMS species fragmentation patterns to account for atypical species, and can thus lead to more complete factor profiles. It is expected that this method would be even more useful for HR-ToF-AMS data, due to the ability to better understand the chemical nature of atypical factors from high resolution mass spectra. Second, utilizing PMF to extract factors containing inorganic species allowed for the determination of extent of neutralization, which could have implications for aerosol parameterization. Third, subtler differences in organic aerosol components were resolved through the incorporation of inorganic mass into the PMF matrix. The additional temporal features provided by the inorganic aerosol components allowed for the resolution of more types of oxygenated organic aerosol than could be reliably re-solved from PMF of organics alone. Comparison of findings from the PMFFull MS and PMFOrg MS methods showed that for the Windsor airshed, the PMFFull MS method enabled additional conclusions to be drawn in terms of aerosol sources and chemical processes. While performing PMFOrg MS can provide important distinctions between types of organic aerosol, it is shown that including inorganic species in the PMF analysis can permit further apportionment of organics for unit mass resolution AMS mass spectra.

Encapsulation of phase change materials using rice-husk-char

This paper explored a new approach to prepare phase change microcapsules using carbon-based particles via Pickering emulsions for energy storage applications. Rice-husk-char, a by-product in biofuel production, containing 53.58 wt% of carbon was used as a model carbon-based material to encapsulate hexadecane. As a model phase change material, hexadecane was emulsified in aqueous suspensions of rice-husk-char nanoparticles. Water soluble polymers poly(diallyldimethyl-ammonium chloride) and poly(sodium styrene sulfonate) were used to fix the rice-husk-char nanoparticles on the emulsion droplets through layer-by-layer assembly to enhance the structural stability of the microcapsules. The microcapsules formed are composed of a thin shell encompassing a large core consisting of hexadecane. Thermal gravimetrical and differential scanning calorimeter analyses showed the phase change enthalpy of 80.9 kJ kg−1 or 120.0 MJ m−3. Design criteria of phase change microcapsules and preparation considerations were discussed in terms of desired applications. This work demonstrated possible utilisations of biomass-originated carbon-based material for thermal energy recovery and storage applications, which can be a new route of carbon capture and utilisation.

Optimization of lipase production from yeasts strains isolated from olive mil wastewater

Dissertação submetida à Universidade de Lisboa, Faculdade de Ciências para a obtenção do Grau de Mestre em Microbiologia Aplicada.