For the first time the interfacial properties of nonionic hydrocarbon surfactants at both the air-water and CO₂-water interfaces are investigated in terms of surfactant structure to determine the changes in surfactant efficiency (negative of the logarithm of the surfactant concentration to create a surface pressure of 20 mN/m). At the air-water interface, linear surfactant tails are more efficient due to the higher packing ability of the straight chains in the dense surfactant monolayer. However, at the CO₂-water interface, surfactant adsorption is small and tails can be solvated. Thus, branching which increases both tail solvation and tail hydrophobicity also enlarges the hard disk area of the surfactant to ultimately increase the efficiency of the surfactant at the CO₂-water interface. CO₂-in-water concentrated emulsions (foams) are studied over short and long times to evaluate the foam stability as a function of both surfactant structure and foam conditions using in-situ optical microscopy. The surface pressure measured at the CO₂- water interface is correlated with the short time stability of coalescing foams with very small cell sizes (under 0.4 [mu]m in diameter). Long time stability of bubbles to coalescence is shown under a variety of conditions. The rheology of these bulk CO₂-in-water foams under high-pressure conditions are also evaluated through measurements of the pressure drop over a capillary tube. Viscosities in excess of 200 cP are measured, an increase of over 1000 time that of pure CO₂ (0.09 cP at 24 °C and 2000 psia). The viscosity of the C/W foams are found to correlate with bubble size, continuous phase viscosity, shear rate, and interfacial tension. Hydrophobic silica particles adsorbed at the interface are also used to stabilize water-in-CO₂ emulsions as an alternative to surfactant stabilizers. The difficulties of tail solvation associated with many hydrocarbon surfactants in CO₂ can be removed by using particles instead of surfactant. A porous cross-linked shell is formed about the hydrophilic (colloidal and fumed) silica to render the particles CO₂-philic and the crosslinking removes ligand tails from the particle surface. / text

Surfactant proteins SP-A and SP-D are important key molecules responsible for pulmonary homeostasis and innate immunity against infectious pathogens. SP-A and SP-D are also found in various parts of the placenta as well as amniotic fluid. The levels of these proteins in the amniotic fluid are good biomarkers of fetal lung maturation. The development of the lungs in fetal growth is important for fetal survival in extrauterine life. In pregnant mice models, a huge increase in SP-A and SP-D levels in the amniotic sac has been reported close to parturition suggesting an important role of these proteins in the hormonal pathway to labour. In this thesis, full length natural and recombinant proteins of human SP-A and SP-D were generated and examined on the maternal-fetal tissues of the placenta (explants of amnion, chorion and decidua) under inflammatory conditions. A range of innate and adaptive immune markers and prostaglandin targets were examined to show that SP-A and SP-D modulate the prostaglandin pathway. Thus, an imbalance in this could potentially lead to disorders such as intrauterine growth retardation and preeclampsia. The cellular basis of immune regulation and prostaglandin pathway was also examined via fractionation of decidual macrophages. Curiously, SP-A and SP-D appears to suppress pro-inflammatory response of decidual macrophages after challenging with LPS. This thesis thus divulges specific and mutually inclusive functions of SP-A and SP-D in the maintenance of pregnancy, protection against intrauterine infection, dampening of inflammation, and premature activation of parturition.

No description available.

Organochlorine pesticides (OCPs) were used in agriculture throughout the world for a long time because they are very effective for pest control, but OCPs such as DDT and its metabolites can threaten human health and ecological systems. Although DDT has been banned for use in Canada since 1972, it still persists in Canadian farmland at detectable levels due to its chemical stability. The soils contaminated with DDT require economical remediation strategies because of the low land value and rural location. Although soil washing has been proposed as a possible economical technique to remove DDT, it has very low water solubility and so it is necessary to consider using surfactants to improve the soil-washing process. Building on previous research, we hypothesize that combinations of surfactants can be used to improve the performance of this remediation method. The surfactants Tween 80, Brij 35, and sodium dodecylbenzene sulfonate (SDBS) were selected based on environmental and reported performance criteria. Combinations of surfactants were tested in both batch and leaching column experiments. Experiments indicated that removal efficiency and flowrate in leaching columns were optimized when a mixture of 2% Brij 35 and 0.1% SDBS was employed. The presence of Tween 80 was found to be less effective, possibly due to its higher biodegradability in the soil. Since the measurement of surfactant concentration in the wash solution is important, several methods were tested before finally selecting a simple COD analysis as a surrogate parameter. Using the COD analysis, partitioning experiments were performed to measure the adsorption of surfactant on the soil. For economic reasons, it would be desirable to reuse the surfactant in a washing process. For this purpose, we employed activated carbon to selectively remove the more hydrophobic DDT from the surfactant solutions. Preliminary results have shown that carbon adsorption can remove some DDT, but additional work is required to understand and optimize the process.

Spontaneous imbibition of water into Fontainebleau Sandstone matrix because of capillary gradient is an important mechanism for oil recovery from Fontainebleau Sandstone reservoirs. Spontaneous imbibition characteristics of Fontainebleau Sandstone core were determined by measuring the Wettability Index of four Fontainebleau Sandstone core samples under laboratory conditions. This was done by utilizing a combination of a Benchtop Relative Permeameter Flooding System and Amott Cups. The specimen had a diameter of 38mm and a height of 47mm. Permeability and porosity of the cores varied from 12 to 14 mD and 10 to 14% respectively. The fluids and chemicals used were kerosene, synthetic brine and Sodium dodecyl sulphate. Amott’s method was used to measure the wettability index. This method consists of four steps: (1) brine flooding, (2) spontaneous imbibition of brine, (3) kerosene flooding, (4) spontaneous imbibition of kerosene. One core was saturated with kerosene and then flooded with brine, followed by spontaneous imbibition of brine. Similarly, another core was saturated with brine and then flooded with kerosene, followed by spontaneous imbibition of kerosene. Similar procedures were used for other two cores except the addition of surfactant to the synthetic brine. All cores were then cleaned and re-saturated for spontaneous imbibition of kerosene and brine. All Experiments were performed under laboratory temperature conditions. Oil and water wettability values were obtained along with secondary and tertiary oil recoveries. These values were used to calculate the wettability index of Fontainebleau sandstone cores. Spontaneous imbibition characteristics of the cores obtained from the experimental data indicate that Fontainebleau Sandstone formation is a potential candidate for Secondary and Tertiary oil recovery by water injection and spontaneous imbibition.

Neonatal respiratory distress syndrome (RDS) is a disease that affects premature infants born prior to 32 weeks gestation. The main cause is a deficiency in pulmonary surfactant due to immature type II pneumocyte cells found in the alveoli. These cells are not capable of producing the required surfactant which normally functions to reduce the surface tension at the air-liquid interface of the lungs, as well as reduce the work of breathing and prevent alveolar collapse. A current treatment method for RDS is exogenous surfactant replacement therapy involving application of an exogenous surfactant preparation directly into the lungs of premature infants. Current surfactant preparations are animal-derived and very costly. Synthetic preparations, on the other hand, are an attractive alternative. The goal of this research is to synthesize a diether phosphonolipid analogue of dipalmitoyl phosphatidylcholine (DPPC), designated DEPN-8. When incorporated into a synthetic exogenous surfactant mixture, DEPN-8 exhibits greater adsorption and surface activity compared to its natural counterpart, DPPC. The synthesis of several components related to the re-tailored synthesis of DEPN-8 will be presented and discussed below. / National Institute of Health, NSERC

Viscoelastic surfactants (VES) have been widely used in acidizing and acid fracturing. They are used as diversion agents during matrix acid treatments and leakoff control agents during acid fracturing. At high temperatures, viscoelastic surfactants hydrolyze, resulting in phase separation after a certain time. Their viscosities significantly decrease and it is much easier for them to flow back causing much less damage to the formation. In this study, 4 to 8 wt% of a new VES-acid system was tested at temperatures of up to 250°F over hydrolysis times of 0 to 6 hours. Then, the solutions were neutralized by calcium carbonate until the pH reached 4.5. An HP/HT rheometer was used to measure the viscosity of the spent acids. Mass spectrometry (MS) was conducted to analyze the hydrolysis products of the VES. Coreflood tests were also conducted on Indiana limestone to determine the effects of the hydrolysis products on the permeability of these cores. The temperature was set at 250°F and the flow rate at 2.5 cm^(3)/s. The viscosities of all VES-acid systems remained high at the beginning of hydrolysis, which was good for acid diversion. After that, the VES acid systems experienced a significant viscosity reduction due to phase separation; it became much easier for the spent acid to flow back. Coreflood experiments caused little damage to the Indiana limestone. MS results indicated hydrolysis of peptide bonds. Fatty acids formed the top oil layer, and amine-based molecules formed the aqueous phase. This study will summarize and discuss the details of viscosity changes of the acid systems of this kind of viscoelastic surfactant, the damage caused by hydrolysis products, and how this kind of viscoelastic surfactant can be used to improve treatments.

This thesis is an investigation into the development of amidine and guanidine based compounds to be employed as switchable surfactants. The surface activity of these molecules can be triggered by reaction with a benign gas, CO2. The ultimate application of these surfactants was to be used as emulsifying and demulsifying agents of crude oil and water emulsions. Synthesis and characterization of the following desired bases: N’-octyl-N,N-dimethylacetamidine (1), 2-octyl-2-imidazoline (2), 1-methyl-2-octyl-2-imidiazoline (3), N’-(4-heptylphenyl)-N,N-dimethylacetamidine (4), N’-(4-(octyloxy)phenyl)-N,N-dimethylacetamidine (5), N’-(4-(methyloxy)phenyl)-N,N-dimethylacetamidine (6), and N-octyl-N',N',N",N"-tetramethylguanidine (7) was carried out. Their solubility in water was quantified with NMR spectroscopy. All bases were reacted with CO2 and H2O to form bicarbonate salts, of which in situ characterization was achieved by IR and NMR spectroscopy. Percent conversion to the protonated forms at elevated temperatures was determined using NMR spectroscopy. A direct correlation between switchability and basicity was observed, as the strongest bases possessed the largest conversions to the protonated species, even at higher temperatures. The enthalpy of protonation was determined for each base through calorimetry experiments. These compounds were tested as demulsifying surfactants of crude oil and water emulsions. Demulsifying ability was determined to differ greatly with the head group structure of the various surfactants. / Thesis (Master, Chemistry) -- Queen's University, 2009-10-27 16:56:13.631

Miniemulsion technology is attracting increasing interest for the preparation of nano-size particles. However, the barrier to industrialising miniemulsion-based products is the lack of an energy efficient and scalable homogenisation device. Current laboratory techniques consist of batch units, however trends are leaning towards developing continuous processes. The objective of the work presented here is to investigate the use of the rotor-stator (RS) and static mixers (SM) as homogenisation devices and ultimately develop a continuous emulsification/polymerisation process for the preparation of miniemulsions. Initially we investigated the RS as a homogenisation device and found that we were able to generate droplets ranging from 300 nm to 2 μm, at industrially pertinent solids content. Subsequently, we investigated the use of SM and compared their performance in terms of mean droplet size evolutions with the rotor-stator. We were able to generate droplets < 200 nm in size and polymerise them in a stable fashion. All the available emulsification devices were then compared in terms of power/energy consumption, droplet size distributions and shear rates. It was observed that with energy costs being of similar orders of magnitude, SM imposed less shear, produced relatively narrow distributions and were better adapted to scale-up, making them the optimal choice for miniemulsification. Energy savings were increased by reducing coalescence during the emulsification step by using in situ generated surfactants, ultimately reducing emulsification time. Neutralising a water-soluble base with an oil-soluble acid almost instantaneously generates in situ surfactants at the oil-water interface. The reduction in emulsification time was partially attributed to the elimination of the relatively slow adsorption step typical of preformed surfactants. These results were used to show that emulsifying in situ formulations at moderate flow rates in line with SMX mixers can substantially reduce emulsification time from 30 minutes, with preformed surfactants, to ~30 seconds. With such a rapid emulsification step, it was possible to test the feasibility of the continuous emulsification process followed by polymerisation in a tubular reactor. Comparing this process with a batch operation, similar results for the ratio of NP/ND and conversion were obtained, but the continuous process was accomplished in a single step. / Thesis (Ph.D, Chemical Engineering) -- Queen's University, 2010-04-19 03:32:08.766

Studying chemical enhanced oil recovery (EOR) in a high-temperature/high-salinity (HT/HS) reservoir will help expand the application of chemical EOR to more challenging environments. Until recently, chemical EOR was not recommended at reservoirs that contain high concentrations of divalent cations without the need to recondition the reservoir by flooding it with less saline/ less hardness brines. This strategy was found ineffective in preparing the reservoir for chemical flooding. Surfactants used for chemical flooding operating in high temperatures tend to precipitate when exposed to high concentrations of divalent cations and will partition to the oil phase at high salinities. In this study amphoteric surfactant was used to replace the traditionally used anionic surfactants. Amphoteric surfactants show higher multivalent cations tolerance with better thermal stability. A modified amphoteric surfactant with lower adsorption properties was evaluated for oil recovery. Organic alkali was used to eliminate the water softening process when preparing the chemical solution and reduce potential scale problems caused by precipitation due to incompatibility between chemical slug containing alkali and formation brine. Using organic alkali helped in minimizing softening required when preparing an alkali-surfactant-polymer (ASP) solution using seawater. Solution prepared with organic alkali showed the least injectivity decline when compared to traditional alkalis (NaOH and Na2CO3) and sodium metaborate. Adding organic alkali helped further reduce IFT values when added to surfactant solution. Amphoteric surfactant was found to produce low IFT values at low concentrations and can operate at high salinity / high hardness conditions. When mixed with polymer it improved the viscosity of the surfactant-polymer (SP) solution when prepared in high salinity mixing water (6% NaCl). When prepared in seawater and tested in reservoir temperature (95°C) no reduction in viscosity was found. Unlike the anionic surfactant that causes reduction in viscosity of the SP solution at reservoir temperature. This will not require increasing the polymer concentration in the chemical slug. Unlike the case when anionic surfactant was used and more polymer need to be added to compensate the reduction in viscosity. Berea sandstone cores show lower recovery compared to dolomite cores. It was also found that Berea cores were more sensitive to polymer concentration and type and injectivity decline can be a serious issue during chemical and polymer injection. Dolomite did not show injectivity decline during chemical and polymer flooding and was not sensitive to the polymer concentration when a polymer with low molecular weight was used. CT scan was employed to study the displacement of oil during ASP, SP, polymer and surfactant flooding. The formation and propagation oil bank was observed during these core flood experiments. ASP and SP flooding showed the highest recovery, and formation and propagation of oil bank was clearer in these experiments compared to surfactant flooding. It was found that in Berea sandstone with a permeability range of 50 to 80 md that the recovery and fluid flow was through some dominating and some smaller channels. This explained the deviation from piston-like displacement, where a sharp change in saturation in part of the flood related to the dominated channels and tapered front with late arrival when oil is recovered from the smaller channels. It was concluded that the recovery in the case of sandstone was dominated by the fluid flow and chemical propagation in the porous media not by the effectiveness of the chemical slug to lower the IFT between the displacing fluid and oil.