Doctor of Philosophy (PhD), Ohio University, 2013, Mechanical Engineering (Engineering and Technology)

Inorganic carbon behavior was measured and modeled to identify a transitional gas phase CO2 concentration for thermophilic cyanobacterial growth in a membrane-based photobioreactor. It was hypothesized that for a given growth system at optimal productivity, there is a gas phase CO2 concentration that will supply necessary inorganic carbon at a rate that matches the photosynthetic demand. Identifying this gas phase concentration is complicated by the chemical composition of the growth media, the mass transfer characteristics of the gas-liquid interface, and the speciation of inorganic carbon that is preferred for the carbon concentration mechanism of the photosynthetic organism. An empirical model of inorganic carbon behavior was developed to more fully understand the behavior of the system and help identify the transitional CO2 concentration. In this research, total inorganic carbon (TIC) concentrations resulting from CO2 absorption in various liquid media were measured, along with changes in pH, using air (380 ppm CO2), 0.1%, 0.5%, 1.0%, 1.5%, 2.0% and 10% CO2 under atmospheric pressure at temperatures of 25, 35, 45, and 55°C. Inorganic carbon behavior was quantified, including the saturation conditions and CO2 mass transfer rates. The rate of change of TIC prior to saturation was used to determine pseudo-CO2 mass transfer coefficients. An empirical model for the CO2 mass transfer was developed to predict inorganic carbon concentrations. The TIC results from the empirical model were validated with experiments. The results indicated that activity coefficients play a much more important role in vapor-liquid equilibrium than fugacity coefficients. Ambient air and CO2 concentrations of 0.1% and 2.0% were used to examine cyanobacteria growth with respect to changes in CO2 levels. TIC, media pH corresponding to fluctuation of TIC, biomass productivity and total dissolved solid (TDS) were used to specify a transitional CO2 concentration. The results of inorga (open full item for complete abstract)

Committee: Bayless David (Committee Co-Chair); Stuart Ben (Committee Co-Chair); Riefler Guy (Committee Member); Vis-Chiasson Morgan (Committee Member); Rose-Grippa Kathaleen (Committee Member) Subjects: Mechanical Engineering

Doctor of Philosophy (PhD), Ohio University, 2021, Chemical Engineering (Engineering and Technology)

Aqueous brines are often produced during hydrocarbon recovery from geological reservoirs as an unwanted by-product. Degree of salinity is always an issue in produced water. In the USA, salt concentration in waters produced from conventional oil and gas wells falls in the range of 1 g/l (~ 0.1 wt.%) to 400 g/l (~ 28 wt.%). Besides salts, CO2 and H2S are ubiquitous in the production stream. Dissolution of these gases in produced waters results in evolution of corrosive species, such as CO2(aq), H2S(aq), H2CO3(aq), H+(aq), HCO-3(aq), and HS-(aq) that cause severe corrosion problems for carbon steel; primary material used in the construction of oil and gas pipelines. Combination of aqueous salts with dissolved CO2(aq) and H2S(aq) and their related species, has always been a great concern for pipeline operators in terms of corrosion problems. A large body of research exists on CO2 and H2S corrosion of oil and gas facilities, mostly at low salt concentrations; up to 3 wt.%. However, only a limited number of studies has investigated CO2 corrosion at high salt concentrations and to the best of this author's knowledge, this number is zero for H2S corrosion. In the present study, the effect of salt (NaCl) concentration on aqueous uniform strong acid, CO2, and H2S corrosion of carbon steel is investigated. The key parameters in the corrosion process that are influenced by salt concentration are identified: transport phenomena (solution density, solution viscosity and diffusion coefficients of dissolved species), solution chemistry, and electrochemistry of the underlying reactions. Models have been reproduced and developed to account for the effect of salinity (up to ~ 5 m NaCl) on transport phenomena and solution chemistry. The Smolyakov and the square root (Kohlrausch law) equations were chosen for correcting the diffusion coefficients for the effect of temperature, and salt concentration, respectively, using new coefficients obtained in this study. The mixed solvent electro (open full item for complete abstract)

Committee: Srdjan Nesic (Advisor); Marc Singer (Committee Member); Sumit Sharma (Committee Member); Rebecca Barlag (Committee Member); Katherine Fornash (Committee Member) Subjects: Chemical Engineering; Environmental Geology; Geochemistry; Materials Science; Petroleum Geology

Doctor of Philosophy (PhD), Ohio University, 2015, Chemical Engineering (Engineering and Technology)

In oil and gas production, internal corrosion of pipelines causes the highest incidence of recurring failures. Ensuring the integrity of ageing pipeline infrastructure is an increasingly important requirement. One of the most widely applied methods to reduce internal corrosion rates is the continuous injection of chemicals in very small quantities, called corrosion inhibitors. These chemical substances form thin films at the pipeline internal surface that reduce the magnitude of the cathodic and/or anodic reactions. However, the efficacy of such corrosion inhibitor films can be reduced by different factors such as multiphase flow, due to enhanced shear stress and mass transfer effects, loss of inhibitor due to adsorption on other interfaces such as solid particles, bubbles and droplets entrained by the bulk phase, and due to chemical interaction with other incompatible substances present in the stream. The first part of the present project investigated the electrochemical behavior of two organic corrosion inhibitors (a TOFA/DETA imidazolinium, and an alkylbenzyl dimethyl ammonium chloride), with and without an inorganic salt (sodium thiosulfate), and the resulting enhancement. The second part of the work explored the performance of corrosion inhibitor under multiphase (gas/liquid, solid/liquid) flow. The effect of gas/liquid multiphase flow was investigated using small and large scale apparatus. The small scale tests were conducted using a glass cell and a submersed jet impingement attachment with three different hydrodynamic patterns (water jet, CO2 bubbles impact, and water vapor cavitation). The large scale experiments were conducted applying different flow loops (hilly terrain and standing slug systems). Measurements of weight loss, linear polarization resistance (LPR), and adsorption mass (using an electrochemical quartz crystal microbalance, EQCM) were used to quantify the effect of wall shear stress on the performance and integrity of corrosion inhibit (open full item for complete abstract)

Committee: Nesic Srdjan Dr. (Advisor) Subjects: Chemical Engineering; Chemistry; Materials Science; Metallurgy

Doctor of Philosophy, The Ohio State University, 2003, Chemical Engineering

Continuous production of microcellular foams, characterized by cell size smaller than 10 μm and cell density larger than 10 9 cells/cm 3 , was studied using supercritical carbon dioxide (CO 2 ) as the foaming agent. Microcellular foams of polystyrene and polystyrene nanocomposites were successfully produced on a two-stage single screw extruder. The contraction flow in the extrusion die was simulated with the FLUENT fluid dynamics computational code to predict profiles of pressure, temperature, viscosity, and velocity. The nucleation onset was determined based on the pressure profile and equilibrium solubility. It was shown that a high CO 2 concentration or a high foaming temperature induces an earlier nucleation near the die entrance. The pressure profile and the position of nucleation onset were correlated to cell nucleation and growth, which helps understand the effects of operating conditions on cell structure. To perform the simulation, viscosity and solubility of the CO 2 /polystyrene system were characterized. Sanchez-Lacombe equation of state was applied to represent the phase equilibrium. Effects of temperature, pressure, and CO 2 content on the shear viscosity were explained using the free volume theory. Systematic experiments were performed to verify effects of three key operating conditions: CO 2 content, pressure drop or pressure drop rate, and foaming temperature, on the foam cell structure. Experimental results were compared with simulations to gain insight into the foaming process. Studies exhibit that a higher pressure drop or pressure drop rate results in smaller cells and greater cell density. Below the CO 2 solubility, cell size decreases and cell density increases with an increase of CO 2 concentration. A high CO 2 concentration favors producing open cell foams. Die temperature affects both cell size and cell structure (open or closed). Combining nano-clay compounding with supercritical CO 2 foaming provides a new technique for the design and con (open full item for complete abstract)

Committee: Kurt Koelling (Advisor) Subjects:

Master of Science (MS), Ohio University, 2006, Chemical Engineering (Engineering)

In this study, the low temperature and high salt concentration effects on CO2 corrosion have been investigated using electrochemical techniques and weight loss (WL) measurements. The study started with general CO2 corrosion experiments at low temperatures (1 – 10°C). It was found that the general CO2 corrosion rate significantly decreased as the temperature decreased. The general CO2 corrosion rate was found to be under charge transfer control at low temperatures (1 – 10°C). It was also found that the experimental data were not consistent with the data predicted by the most advanced corrosion prediction model. A series of experiments were also performed to study high salt concentration effects on general CO2 corrosion. The corrosion rates of carbon steel were found to be significantly affected by the high content of salt. The corrosion rates decrease significantly and nonlinearly with the increase of salt concentration. It was also found from the potentiodynamic results that the high salt concentration retarded the cathodic reaction, the anodic reaction and the limiting current. A modification to the well known published electrochemical model was made to account for the low temperature and high salt effects. The modified model agrees well with the experimental data at low temperatures and high salt concentrations.

Committee: Srdjan Nesic (Advisor) Subjects: Engineering, Chemical