Cette thèse s'est inscrite dans le cadre du projet ACACIA (Amélioration du CAptage du CO2 Industriel et Anthropique) soutenue par le pôle de compétitivité AXELERA et financé par " FUI " et " LE GRAND LYON ". Notre objectif était d'immobiliser l'anhydrase carbonique dans des gels inorganiques, en particulier la silice afin de préserver la structure de l'enzyme, sa fonctionnalité et de la protéger de l'environnement physico-chimique environnant. Pour cela, des essais préliminaires simples nous ont permis d'élaborer et de construire une cellule, comprenant membrane polymérique poreuse imprégnée de solution enzymatique aqueuse, ou de gel de silice lui-même imprégné de solution aqueuse d'enzyme. A partir de ce montage, nous avons étudié des paramètres importants de la membrane, comprenant un tampon, sa nature, molarité et son pH, ainsi que la taille des pores de la membrane et la concentration en enzyme. Il a été trouvé qu'un tampon à base de bicarbonate permet de déplacer l'équilibre de déprotonation du CO2(aq) vers un pH plus élevé, par l'apport des ions HCO3- équilibrés par des cations comme Na+, et favorise une contribution plus importante à la diffusion du CO2 à travers la membrane. Nous avons également observé que quelque soit le gaz de captage (100 % et / ou 10 % de CO2), le tampon et le type de membrane, une perméance maximum a été observée pour une concentration en enzyme de 0.2 mg mL-1.

This investigation tested simulated saline lake environments as mineralization sites for sequestering anthropogenic CO2. Four unique saline lakes were simulated in the laboratory. Two sets of experiments were conducted by diffusing CO2(g) through each simulated lake over 30 days. The first set tested the carbonate system response to elevated CO2(g). The second set of experiments replicated the same process but used ammonium hydroxide to elevate pH. Water samples were collected daily to test for cation loss via mineralization. Rapid mineralization occurred with the pH enhancer and cation activity was greatly reduced by as much as 38,000 mg/L Ca due to precipitation. This resulted in a mass of 100,000 mg/L of CO2 being sequestered via Ca and Mg-carbonate mineralization. With proper geochemical conditions, saline lake environments can therefore potentially serve a purpose in sequestering CO2(g).

Electrochemical frequency modulation (EFM), which has been widely used in the research field of semiconductors, was used to study CO2 corrosion on carbon steel under film forming and non-film forming conditions. In the EFM technique two sinusoidal voltage signals of different frequencies are applied to the system and the response current is measured at zero, harmonic and intermodulation frequencies from which the corrosion rate is calculated. The corrosion rate calculation depends upon whether the system is under activation, diffusion or passivation control. In this research rotating cylindrical electrodes made of AISI carbon steel 1018 were immersed in 3% (w/w) NaCl solution saturated with carbon dioxide. The experiment was done at 5 rpm, 24 rpm and 100 rpm simulating laminar, transient and turbulent flow regions respectively. The exposure time was varied from 1 hour to 24 hours and the results were compared with other electrochemical methods such as linear polarization (LP) and electrochemical impedance spectroscopy (EIS). It was found that it was crucial to select the correct EFM model to ensure accurate corrosion rate measurement. A very good agreement in the polarization resistance was obtained between EIS and EFM indicating that EFM can be used as an effective tool in corrosion studies providing that the corrosion mechanism is known.

The kraft pulping process has been known for decades. The focus in kraft pulping has always been on better operation of the chemical recovery system. One of the targets is on deadload (sodium sulfate (Na2SO4) and sodium carbonate (Na2CO3)) reduction in white liquor. A model based on several literature references was developed to study the effect of deadload reduction. A base model was developed based on current mill operation. This base model was compared to the deadload reduction model. Overall improvement, such as operating cost saving and revenue generation was achieved from deadload reduction. Operating cost saving involves less deadload chemical in chemical recovery system, and less water that was associated with the deadload itself. Revenue generation involves generating more steam and heat from the recovery boiler that can be used for mill purposes or energy revenue. Two important variables to achieve deadload reduction are causticizing efficiency and reduction efficiency.

Advanced Methods, Materials, and Devices for Microfluidics Celesta E. White 217 Pages Directed by Dr. Clifford L. Henderson Microfluidics is a rapidly growing research area that has the potential to influence a variety of industries from clinical diagnostics to drug discovery. Unlike the microelectronics industry, where the current emphasis is on reducing the size of transistors, the field of microfluidics is focusing on making more complex systems of channels with more sophisticated fluid-handling capabilities, rather than reducing the size of the channels. While lab-on-a-chip devices have shown commercial success in a variety of biological applications such as electrophoretic separations and DNA sequencing, there has not been a significant amount of progress made in other potential impact areas for microfluidics such as clinical diagnostics, portable sensors, and microchemical reactors. These applications can benefit greatly from miniaturization, but advancement in these and many other areas has been limited by the inability or extreme difficulty in fabricating devices with complex fluidic networks interfaced with a variety of active and passive electrical and mechanical components. Several techniques exist for the fabrication of microfluidic devices, but these methods have significant limitations, and alternative fabrication approaches are currently desperately needed. One such method that shows promise for its ability to integrate the desired high levels of functionality utilizes thermally sacrificial materials as place holders. An encapsulating overcoat material provides structural stability and becomes the microchannel walls when the sacrificial material is removed from the channel through thermal decomposition. Disadvantages of this method, however, include numerous processing steps required for sacrificial layer patterning and elevated temperatures needed for the decomposition of initial sacrificial materials. These limitations keep this method from becoming an economical alternative for microfluidic device fabrication. The materials needed for this method to reach its full potential as a valid fabrication technology for m-TAS are not currently available, and it was a major focus of this work to develop and characterize new sacrificial materials, particularly photosensitive polycarbonate systems. In addition to the development of new sacrificial polymers, the framework for a working microfluidic device was developed to show that this concept will indeed provide significant advancements in the development of future generations of microfluidic systems. Finally, novel fabrication methods for microfluidics through combined imprinting and photopatterning of photosensitive sacrificial materials was demonstrated.

No description available.

No description available.

The purpose of this study was first to develop a method by which a detailed porosity classification system could be utilized to understand the relationship between pore/pore-throat geometry, genetic porosity type, and facies. Additionally, this study investigated the relationships between pore/pore-throat geometry, petrophysical parameters, and reservoir performance characteristics. This study focused on the Jurassic Smackover reservoir rocks of Grayson field, Columbia County, Arkansas. This three part study developed an adapted genetic carbonate pore type classification system, through which the Grayson reservoir rocks were uniquely categorized by a percent-factor, describing the effect of diagenetic events on the preservation of original depositional texture, and a second factor describing if the most significant diagenetic event resulted in porosity enhancement or reduction. The second part used petrographic image analysis and mercury-injection capillary pressure tests to calculate pore/pore-throat sizes. From these data sets pore/pore-throat sizes were compared to facies, pore type, and each other showing that pore-throat size is controlled by pore type and that pore size is controlled primarily by facies. When compared with each other, a pore size range can be estimated if the pore type and the median pore-throat aperture are known. Capillary pressure data was also used to understand the behavior of the dependent rock properties (porosity, permeability, and wettability), and it was determined that size-reduced samples, regardless of facies, tend to show similar dependent rock property behavior, but size-enhanced samples show dispersion. Finally, capillary pressure data was used to understand fluid flow behavior of pore types and facies. Oncolitic grainstone samples show unpredictable fluid flow behavior compared to oolitic grainstone samples, yet oncolitic grainstone samples will move a higher percentage of fluid. Size-enhanced samples showed heterogeneous fluid flow behavior while the size-reduced samples could be grouped by the number of modes of pore-throat sizes. Finally, this study utilized petrographic image analysis to determine if 2- dimensional porosity values could be calculated and compared to porosity values from 3-dimensional porosity techniques. The complex, heterogeneous pore network found in the Grayson reservoir rocks prevents the use of petrographic image analysis as a porosity calculation technique.

Authigenic carbonate rock (ACR) is derived from microbial oxidation of methane, biodegradation of crude oil, and oxidation of sedimentary organic matter. The precipitation of ACR was characterized petrographically, mineralogically, and geochemically. ACR collected from the seafloor in the Gulf of Mexico (GOM) and ACR recovered from drilled cores in the Krishna-Godawari (KG) basin offshore India were used. All study sites are associated with hydrocarbon gas venting, seepage, free gas, or gas hydrate. ACR from the GOM is densely cemented and extremely irregular in shape, whereas ACR from offshore India is generally an oval-shaped smooth nodule and also densely cemented. The dominant mineral in ACR is authigenic calcite. ACR contains carbon derived from sedimentary organic carbon oxidation that geologically sequesters much fossil carbon. Bulk carbon and oxygen isotopes of ACR were measured. ACR from the GOM is strongly depleted in 13C with ?13C of ?42.5? and enriched in 18O with ?18O of 4.67?. The ?13C of hydrocarbon is typically more depleted in 13C than in the associated ACR. The reason is that authigenic carbonate cements from hydrocarbon oxidation generally enclose skeletal material characterized by normal marine carbonate. Three groups that represent different hydrocarbon sources to ACR were classified in this study: primary carbon sources to ACR from (1) methane plus biodegraded oil, (2) methane, or (3) biodegraded oil. Wide ranges in ?13C (?49.12 to 14.06?) and ?18O ( 1.27 to 14.06?) were observed in ACR from offshore India. In sediments, the ?13C may be affected by differences in the rate of organic carbon oxidation, which generate varying ?13C with depth during methanogenesis. Based on the wide range in ?13C, ACR from offshore India was classified: (1) ?13C may reflect high rates of organic carbon oxidation, (2) ACR may be derived primarily from methane oxidation, and (3) ?13C may reflect low rates of organic carbon oxidation. ?18O values are heavier than those of normal marine carbonates. The ?18O may be caused by reaction with deep-sourced water that was isotopically heavier than ambient seawater. Some samples may reflect heavy ?18O from gas hydrate decomposition, but it would not cause significant heavy oxygen isotopes.

A transect of cores ranging from 798 m to 1585 m water depth in the South Atlantic Ocean document the relative intermediate water mass nutrient geometry and stable isotopic variability of AAIW during the Younger Dryas cooling event. The data reveal concurrent delta^13 C and delta^18 O excursions of 0.59 ppt and 0.37 ppt within the core of Antarctic Intermediate Water (AAIW) centered at 11,381 calendar years before present based on radiometric age control. A portion of the delta^1 3C variability (0.22 ppt) can be explained by a shift in thermodynamic equilibrium concurrent with a drop in temperature of 1.8°C at the locus of AAIW formation. The remaining 0.37 ppt increase in delta^13 C most likely resulted from increased wind velocities, and a greater coupling between the ocean and the atmosphere at the locus of AAIW formation (increased efficiency of the thermodynamic process). Deepwater coral mounds are aggregates of corals, other organisms, their skeletal remains, and sediments that occur on the seafloor of the world’s oceans. In the Straits of Florida, these features have been referred to as lithoherms. We use digital, side-scan sonar data collected from the submarine NR-1 from an 10.9 km^2 area at ~650 m water depth to characterize quantitatively aspects of the morphology of 216. Their lengths, widths, heights, areas, orientations and concentration on the seafloor have been determined. Analysis indicates that the outlines of relatively small to medium sized lithoherms can be effectively described with a piriform function. This shape is less applicable to the largest lithoherms because they are aggregates of smaller lithoherms. Nearly all of the lithoherms studied have axes parallel to the northward flowing Florida Current, and the heads of 80 percent of these features face into the current. The shape and orientation of the lithoherms, and evidence of megaripples and scouring in the sonar data suggest that these features are formed by a unidirectional current. Following an extensive investigation of over 200 lithoherms via side-scan sonar imagery and direct observation, we have developed a qualitative model for the formation of the lithoherm type of deep-water coral mounds in the Straits of Florida. Lithoherm formation can be characterized by four main stages of development: nucleating, juvenile, mature singular, and fused. Fused lithoherms can form via transverse and/or longitudinal accretion, however, transverse accretion at the head of the mound is likely the most efficient mechanism. A comparison of lithoherm spatial relationship to local bathymetry agrees with previous observations of deep-water coral mound formations along the levied margins of density flow scour channels.