Browsing by Author "Tomson, Mason B"

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    A Systematic Study of Short and Long Range Interactions in Associating Fluids Using Molecular Theory
    (2015-12-17) Ahmed, Wael; Chapman, Walter G; Cox, Kenneth R; Tomson, Mason B; Biswal, Sibani L
    Parameters needed for the Statistical Associating Fluid Theory (SAFT) equation of state are usually fit to pure component saturated liquid density and vapor pressure. In this thesis, other sources of information such as quantum mechanics, infinite dilution properties, Fourier transform infrared (FT-IR) spectroscopy and molecular dynamic (MD) simulation are used to obtain a unique set of parameters for complex fluids such as water and alcohols. Consequently, the equation of state can be more predictive and the parameters are not anymore system dependent. Moreover, the four vertices of the molecular thermodynamic tetrahedron (phase equilibrium experiments, spectroscopy, MD simulation and molecular theory) are used to study the distribution of hydrogen bonds in water and alcohol containing mixtures. The new sets of physical parameters and the knowledge gained in studying hydrogen bonding are then applied to model water content of sour natural gas mixtures as well as the phase behavior of alcohol + n-alkane and alcohol + water binary systems. Accurate determination of the water content in hydrocarbons is critical for the petroleum industry due to corrosion and hydrate formation problems. Experimental data available in the literature on the water content of n-alkanes (C5 and higher) is widely scattered. The perturbed chain form of the SAFT equation of state (PC-SAFT) was used to accurately correlate water mole fraction in n-alkanes, C1 to C16, which are in equilibrium with liquid water or ice. In addition, a list of experimental data is recommended to the reader based on its agreement with the fundamental equation of state used in this dissertation. The proposed molecular model was then applied to predict water content of pure carbon dioxide (CO2), hydrogen sulfide (H2S), nitrous oxide (N2O), nitrogen (N2) and argon (Ar) systems. The theory application was also extended to model water content of acid gas containing mixtures in equilibrium with an aqueous or a hydrate phase. To model accurately the liquid-liquid equilibrium (LLE) at subcritical conditions, cross association between CO2, H2S and water was included. The hydrate phase was modeled using a modified van der Waals and Platteeuw (vdWP) theory. The agreement between the model predictions and experimental data measured in our lab was found to be good across a wide range of temperatures and pressures. Modeling the phase behavior of liquid water can be quite challenging due to the formation of complex hydrogen bonding network structures at low temperatures. However, alcohols share some similarities with water in terms of structure and physical interactions. As a result, studying alcohol + n-alkane binary systems can provide us with a better understanding of water-alkane interactions. Besides, the application of alcohols in the petroleum and the biodiesel industry is of great importance. As a result, Polar PC-SAFT was used to model short chain 1- alcohol + n-alkane mixtures. The ability of the equation of state to predict accurate activity coefficients at infinite dilution was demonstrated as a function of temperature. Investigations show that the association term in SAFT plays an important role in capturing the right composition dependence of the activity coefficients in comparison to excess Gibbs free energy models (UNIQUAC in this case). Results also show that considering long range polar interactions can significantly improve the fractions of free monomers predicted by PC-SAFT in comparison to spectroscopic data and molecular dynamic (MD) simulations. Additionally, evidence of hydrogen bonding cooperativity in 1-alcohol + n-alkane systems is discussed using spectroscopy, simulation and theory. In general, results demonstrate the theory’s predictive power, limitations of Wertheim’s first order thermodynamic perturbation theory (TPT1) as well as the importance of considering long range polar interactions for better hydrogen bonding thermodynamics. Furthermore, the thermodynamics of hydrogen bonding in 1-alcohol + water binary mixtures is studied using MD simulation and Polar PC-SAFT. The distribution of hydrogen bonds in pure saturated liquid water is computed using TIP4P/2005 and iAMOEBA simulation water models. Results are compared to spectroscopic data available in the literature and to predictions using Polar PC-SAFT. The distribution of hydrogen bonds in pure alcohols is also computed using the OPLS-AA force field. Results are compared to Monte Carlo (MC) simulations available in the literature and to predictions using Polar PC-SAFT. The analysis show that hydrogen bonding in pure alcohols is best predicted using a two-site model within the SAFT framework. On the other hand, simulations show that increasing the concentration of water in the mixture increases the average number of hydrogen bonds formed by an alcohol molecule. As a result, a transition in association scheme occurs at high water concentrations where hydrogen bonding is now better captured using a three site alcohol model within the SAFT framework. The knowledge gained in understanding hydrogen bonding is applied to model the vapor-liquid equilibrium (VLE) and LLE of 1-alcohol + water mixture using Polar PC-SAFT. Predictions are in good agreement with experimental data, thus exhibiting the equation of state predictive power.
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    Co-transport of Carboxyl-functionalized Multi-walled Carbon Nanotubes and Kaolinite in Saturated Porous Media
    (2015-04-22) Wang, Tianxiao; Li, Qilin; Alvarez, Pedro J; Tomson, Mason B
    Co-transport behavior of carboxylated multiwalled carbon nanotubes (COOH-MWCNTs) and kaolinite in various solution ionic strength (IS) and pH were investigated. Results on electrophoretic mobility of CNT, kaolinite and quartz sand as well as particle size of CNT-kaolinite mixture, CNT alone and kaolinite alone were consistent with the DLVO theory. Large particle sizes of kaolinite-CNT mixture revealed potential heteroaggregations especially at 1 mM NaCl, pH=3 and 10 mM NaCl and pH=9. Deposition of CNT was enhanced during the co-transport at 1mM NaCl and pH=3 due to the low mobility of CNT-kaolinite heteroaggregate while decreased at pH=5 in 1 mM NaCl, pH=9 in 10 mM NaCl and pH=9 in 100 mM NaCl because of site blocking by kaolinite. Kaolinite mobility increased in the presence of CNT at pH=3 in 1 mM NaCl caused by site blocking and at pH=9 in 10 mM NaCl resulted from low single collector efficiency of large particles.
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    Development of a Predictive and Mechanistic Model for Capacitive Deionization
    (2015-10-22) Heldenbrand, Amy M; Li, Qilin; Alvarez, Pedro J.J.; Tomson, Mason B
    The objective of this research was to develop a mechanistic and predictive model for capacitive deionization (CDI). The commonly-known Gouy Chapman Stern (GCS) model was modified to account for finite ion size and pore geometry by including the Carnahan-Starling (CS) equation of state and considering boundary conditions resulting from difference in pore shape and size and the subsequent impact on potential and concentration profiles. This GCS-CS model with pore geometry was applied to six model activated carbons (MACs) of uniform pore size to analyze the effect of influent salt concentration, pore size and geometry, and applied voltage on ion removal. The general trends found in modeling results were consistent with data presented in the literature. These findings were then compared with the commonly used CDI models, which could not replicate them. This indicates the complexity present in this new model is necessary for accurate representation of ion adsorption in CDI.
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    Nanomaterials for Hydrocarbon Exploration, Acid Gas Removal and Energy Devices
    (2015-04-08) Ruan, Gedeng; Tour, James M.; Wilson, Lon J; Tomson, Mason B
    This thesis discusses the synthesis and characterization of several different nanomaterials as well as their applications to oil and energy industries. The nanomaterials studied here include asphalt-derived high surface area activated porous carbon, commercial carbon black (CB), nanoporous metal compounds, graphene, and graphene nanoribbons (GNRs). Through proper design and functionalization, these nanomaterials exhibit interesting properties and their applications in hydrocarbon exploration, acid gas removal as well as energy devices are demonstrated. Firstly, the research activities toward the development of new absorbents for carbon dioxide (CO2) capture have been growing quickly. Despite the variety of existing materials with high surface areas and high CO2 uptake performances, the cost of the materials remains a dominant factor in slowing their industrial applications. In the first chapter we study preparation and CO2 uptake performance of highly porous carbon materials derived from a very inexpensive carbon source, asphalt. Carbonization of asphalt with potassium hydroxide (KOH) at high temperatures (600 - 750 ºC) yields asphalt-derived porous carbon materials (A-PC) with high surface areas of up to 2780 m2 g-1 and high CO2 uptake performance of 21 mmol g-1 or 93 wt% at 30 bar and 25 ºC. Furthermore, nitrogen doping and reduction with hydrogen yields active N-doped materials (A-NPC and A-rNPC) containing up to 9.3% nitrogen, making them nucleophilic porous carbons with further increase in CO2 uptake to 26 mmol g-1 or 114 wt% at 30 bar and 25 ºC for A-rNPC. This is the highest reported CO2 uptake among the family of the activated porous carbonaceous materials. The CO2 is released and the asphalt material is regenerated when the pressure is returned to 1 bar. Thus the porous carbon materials from asphalt have excellent properties for reversibly capturing CO2 at the well-head during the extraction of natural gas, a naturally occurring high pressure source of CO2. Through a pressure swing sorption process, the asphalt-derived material is a reversible capture medium that is highly efficient and very inexpensive. Secondly, crude oil is called as “sour” crude oil when the total sulfur level is larger than 0.5 %. The sour crude oil is corrosive to the oil production and transportation facilities and toxic to human health. Among these sulfur species, H2S is the one of main impurities in sour crude. Therefore it is important to develop a method to accurately measure the sulfur content which may help geologists evaluate the quality of the crude oil before large scale extraction. In the second chapter, we study polyvinyl alcohol functionalized carbon black (PVA-CB) nanoparticles which are stable under high temperature and high salinity conditions. After further being functionalized with H2S-sensitive fluorescence probe, the probe molecule-PVA-CB (FB-PVA-CB) can be used to determine the H2S content in H2S-containing oil in porous rock based on the fluorescent enhancement of the H2S-sensitive addends. Thirdly, a flexible 3-dimensional (3-D) nanoporous NiF2-dominant layer on poly(ethylene terephthalate) has been developed. The nanoporous layer itself can be freestanding without adding any supporting carbon materials or conducting polymers. By assembling the nanoporous layer into two-electrode symmetric devices, the inorganic material delivers battery-like thin-film supercapacitive performance with a maximum capacitance of 66 mF cm-2 (733 F cm-3 or 358 F g-1), energy density of 384 Wh kg-1 and power density of 112 kW kg-1. Flexibility and cyclability tests show that the nanoporous layer maintains its high performance under long-term cycling and different bending conditions. The fabrication of the 3-D nanoporous NiF2 flexible electrode could be easily scaled. Fourthly, in its monolayer form, graphene is a one-atom-thick two-dimensional material with excellent electrical, mechanical and thermal properties. Large-scale production of high-quality graphene is attracting an increasing amount of attention. Chemical vapor and solid deposition methods have been developed to grow graphene from organic gases or solid carbon sources. Most of the carbon sources used were purified chemicals that could be expensive for mass production. In this work, we have developed a less expensive approach using six easily obtained, low or negatively valued raw carbon-containing materials used without pre-purification (cookies, chocolate, grass, plastics, roaches, and dog feces) to grow graphene directly on the backside of a Cu foil at 1050 °C under H2/Ar flow. The non-volatile pyrolyzed species were easily removed by etching away the frontside of the Cu. Analysis by Raman spectroscopy, X-ray photoelectron spectroscopy, ultraviolet-visible spectroscopy and transmission electron microscopy indicates that the monolayer graphene derived from these carbon sources is of high quality. Fifthly, the preparation of polymer-functionalized graphene nanoribbons (PF-GNRs) in a one-pot synthesis is described. Multiwalled carbon nanotubes (MWCNTs) were intercalated by potassium under vapor- or liquid-phase conditions, followed by addition of vinyl monomers, resulting in PF-GNRs. Scanning electron microscopy, thermogravimetric mass spectrometry and X-ray photoelectron spectroscopy were used to characterize the PF-GNRs. Also explored here is the correlation between the splitting of MWCNTs, the intrinsic properties of the intercalants and the degree of defects and graphitization of the starting MWCNTs. The PF-GNRs could have applications in conductive composites, transparent electrodes, heat circuits and supercapacitors.
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    Solubility prediction of scale minerals and study of nucleation kinetics at temperature below 250°C
    (2020-08-31) Deng, Guannan; Tomson, Mason B
    The temperature and pressure limit of brine in oil & gas wells is typically below 205oC and 24,000 psi. Generally, the impact of temperature change on properties of brine is more significant than the effect of pressure. High temperature (above 100oC) related research is sparse because of experimental challenges, most research setup at low temperature should be fundamentally changed to be applied to high-temperature environments. Research at high-temperature high-pressure (HTHP) is the most challenging because of the need for special materials and cautious experimental procedures. In this research, by measuring the solubility of anhydrite at concentrated high [Ca] solution below 220oC and the following Pitzer modeling with updated database, as well as measuring induction time of barite nucleation using a novel laser-hydrothermal apparatus, we aim to quantitatively understand the effect of temperature on thermodynamics and kinetics of some sulfate scale minerals. Solubility measurement of scale minerals in electrolyte solution is a mature field, the research boundary has shifted to combined conditions of high temperature, high pressure and high salinity. In Chapter 2, the solubility of calcium sulfate anhydrite was measured in the presence of high NaCl and CaCl2 concentrations at temperatures from 120oC to 220oC. A static hydrothermal reactor method was used, solubility equilibrium was verified by continuously monitoring both [Ca2+] and [SO42-], as well as comparison of results with the literature. Solubility of anhydrite in CaCl2 solution ranged from 0-1.33 m shows a continuous decrease with temperature, when CaCl2 concentration increases at a constant temperature, the solubility of anhydrite increases at T>175oC due to higher ionic strength but shows a complex behavior below 175oC. Another setup is the solubility of anhydrite in the presence of mixed NaCl-CaCl2 solution with a constant ionic strength of 4 m, results show that solubility at low calcium concentration (0.25 m CaCl2, 3.25 m NaCl) is significantly higher than that with higher Ca2+ concentration, which can be explained by the Ca2+ common ion effect. When CaCl2 concentrations increase to 0.5 m, 0.75 m, 1 m, and 1.33 m, anhydrite solubility does not change significantly at a constant ionic strength of 4 m within the temperature range, suggesting that common ion effect is only significant at low Ca concentrations. In Chapter 3, solubility data from Chapter 2 are incorporated into a database of Pitzer-Debye-Hückel model, wherein thousands of thermodynamic data of sulfate minerals (barite, celestite, gypsum, and anhydrite) were integrated to give the best regression of ion-ion interaction parameters, especially the bivalent Ca-SO4 interaction parameters. The revision of Ksp values of sulfate minerals at HPHT and the multivariate linear regression procedure are also discussed in detail. In Chapter 4, we designed a laser hydrothermal reactor to examine barite nucleation induction time up to 250oC. A stainless 316 aging cell was equipped with two sight windows on its wall, through which a laser beam penetrates to monitor the turbidity change of solution inside. Barite supersaturation was established by injecting concentrated 0.5 ml of BaCl2 and Na2SO4 solution into about 200 g background solution (1 m NaCl, 0.025 m CaCl2), with saturation index (SI) range from 0.4 to 1.2 and temperature range 90oC to 250oC. Results show expected behavior that induction time decreases with both SI and temperature. The effect of two thermally stable chemical additives, branded polymer inhibitors of sulfonated carbonate copolymer (SCC) and polyvinyl sulfonate (PVS), was also examined at 200oC. Again, an expected inhibition pattern was observed, induction time decrease with inhibitor concentration (0-2 ppm) at constant SI value. These results imply that the change of induction time with SI and inhibitor concentration follows a similar trend from temperature range 4oC and 250oC.
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    Solubility, Precipitation Kinetic, and Chemical Control of Iron Sulfide
    (2024-04-18) Wang, Xin; Tomson, Mason B; Chapman, Walter G; Getachew, Bezawit
    The iron sulfides (FeS) constitute a diverse group of solids and dissolved complexes, many of which play critical roles in the natural system, such as marine sedimentation and biochemical processes. It has also become a significant problem in various industrial processes, such as water and wastewater treatment, metal equipment corrosion by hydrogen sulfide, and oil and gas production. Extensive studies have been done in the past century to better understand, predict, and control the sulfide mineral precipitation, of which the importance can never be overstated. In this work, a systematic study of the solubility, precipitation kinetics, and the chemical dispersion control of iron sulfide is conducted to better understand iron sulfide scale prediction and control in industrial processes.