Direct methanol fuel cell (DMFC) were characterized with low operation temperature, high energy density, rapid activation, easy to obtain, easy to carry, safety, stability and low pollution. Therefore, DMFCs were thought as the next generation of power suppliers to replace lithium battery in the future. In order to meet the miniaturization demand of portable electronic devices, this research tried to fabricate a £gDMFC, simplify component, and lower cost by using MEMS technique. This research used TMAH etching, PEACE, and KOH etching, CNT growth technique to fabricate the hill-like diffusion layer (HDL) electrode which combined the channel structure and through-hole silicon (THS) electrode. Another emphasis of this research was to improve the bubble cover problem for £gDMFCs. The bubble cover problem resulted from the CO2 bubble generated in methanol oxidation reaction difficultly removed and resulted in adverse effect for reaction. This research tried to use the surfactants which used in electroforming to improve the bubble cover problem by improvement surface tension of fuel. Experiments show that using the HDL electrode in anode and the THS electrode in cathode would get the maximum power density (0.186 mW/cm2). The powder density of the design £gDMFC is 10 and 2.5 times larger than the one with pure carbon paper electrodes and the HDL electrodes. Surfactant MA was suitable as a wetting of methanol. Bubble size could reduce 1/2 to 1/3 and bubble cover area could reduce 20% by adding MA. Add MA in the fuel cell could help the bubbles remove to avoid the bubble cover problem. Though MA addition would have the adverse effect for methanol reaction, could get the stabile voltage and extend the discharge time.

A new type of viscoelastic amphoteric surfactants (amidoamine oxide) has been examined as a diverting agent during acidizing treatment. Rheological properties of viscoelastic surfactants are a function of surfactant concentration, acid additives, pH, temperature and shear rate. A HPHT rheometer was used to test the effect of common acid additives and organic acids/chelating agents on the apparent viscosity of amidoamine oxide-based acids. The compatibility and thermal stability of surfactants with corrosion inhibitor were also investigated. Rotating disk apparatus was used to examine the kinetic studies of surfactant-based acids with limestone. The results show that the apparent viscosity of surfactant solutions prepared in deionized water, live acid, and spent acid was found to be a function of temperature. Apparent viscosity of live surfactant-based acids was also found to be a function of HCl concentration. Most of acid additives could adversely affect the rheological properties of spent acids. Compatibility tests should be done prior the field application. Cryo-TEM studies show the changes of rod-like micelle structures with the addition of additives. The reaction between surfactant-based acid and limestone was found to be mass transfer limited at 170 degrees F.

Carbonate reservoirs are heterogeneous; therefore, proper acid placement/diversion is required to make matrix acid treatments effective. Viscoelastic surfactants (VES) are used as diverting agents in carbonate matrix acidizing. However, these surfactants can adversely affect wettability around the wellbore area. Lab and field studies show that significant amounts of VES are retained in the reservoir, even after an EGMBE postflush. Optimizing acid treatments requires a study of the effect of VES on wettability. In a previous study using contact angle experiments, it was reported that spent acid solutions with VES only, and with VES and EGMBE are water-wetting. In this thesis, we studied the effect of two amphoteric amine-oxide VES', designated as "A" and "B" on the wettability of Austin cream chalk using contact angle experiments. We extended the previous study by using outcrop rocks prepared to simulate reservoir conditions, by demonstrating that VES adsorbs on the rock using two-phase titration experiments, by studying the effect of temperature on wettability and adsorption, and by developing a detailed procedure for contact angle experiments. We found that for initially oil-wet rocks, simulated acid treatments with VES "A" and "B" diversion stages and an EGMBE preflush and postflush made rocks water-wet at 25, 80, and 110 degrees C. Simulated acid treatments with a VES "A" diversion stage only made rocks water-wet at 25 degrees C. Our results suggest that both VES formulations cause a favorable wettability change for producing oil. The two-phase titration experiments show that both VES "A" and "B" adsorb on the rock surface. From our literature review, many surfactant wettability studies use contact angle measurements that represent advancing contact angles. However, wettability during stimulation is represented by receding contact angles. Results of static receding contact angles may be misinterpreted if low oil-acid IFT's cause oil droplets to spread. Spreading could be a reflection of the effect of the surfactants on the fluid-fluid interface rather than the rock-fluid interface. The new procedure shows the effect of VES and EGMBE on the rock-fluid interface only, and so represents the actual wettability.

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Adsorption kinetics and adsorption-desorption of atrazine on organoclay composites prepared with the surfactant 6-piperazin-1-yl-N,N'-bis-(1,1,3,3-tetramethyl-butyl)-(1,3,5)triazine-2,4-diamine and Houston Black clay were studied using the indirect batch equilibration procedure. The organoclay composites sorbed significantly more atrazine than the Houston Black clay. Adsorption equilibrium was reached after 72 h for the organoclay composites. Atrazine adsorption isotherms were described by linear partitioning. The Koc values ranged from 605 to 5271 L kg-1 for the organoclay composites compared to a value of 41 L kg-1 for the Houston Black clay. The organoclay composite containing 20% surfactant on a total weight basis provided the most efficient adsorption of atrazine, although organoclay composites containing much lower amounts of surfactant also adsorbed significant amounts of atrazine. An average of 11% of sorbed atrazine was released during desorption. Characterization of desorption products showed only atrazine molecules being released from the organoclay composites.

Factors that affect liquid chemical intervention methods of controlling pathogens on fresh-cut produce were investigated. The relationship between produce tissue structure (intercellular space, cell size, and cell distribution) and the sanitizing effectiveness of liquid chemical treatment was studied. Experiments determined if sanitizer contact with bacteria could be improved through the use of surfactants and different application methods (drop application method, negative pressure differential, and sonication). To test these factors, a model sanitizer, H2O2, and a model microorganism: Salmonella Typhimurium, along with various fresh-cut produce (apple, pear, carrot, and potato) were tested. Microscopic analysis revealed a very complicated pore structure consisting of irregular capillaries. S. Typhimurium was found to survive in all produce tested, and washing did not significantly reduced inoculated bacteria regardless of the bacterial incubation time or produce type. The results showed that a 3% H2O2 solution reduced S. Typhimurium in produce and the solution’s efficiency varied in the following descending order: potato>apple>carrot>pear. In seven min treatments, bacteria were reduced by 2.5 CFU/ml in potato, 2.3 CFU/ml in apple, 1.5 CFU/ml in carrot, and 0.7 CFU/ml in pear. There was no direct evidence on how intercellular space, its percentage or cellular distribution and shape affected efficiency, but some possibilites were discussed. The rate and extent of liquid penetration, and how varying pore diameter in each cell or air space prevent complete chemical treatment penetration were also analyzed. It was determined that bacterial density has a slight effect in bacterial reduction but this depends on type of produce inoculated. The use of surfactants did not improve bacterial reduction in either washing or chemical treatments, and neither did the use of drop application method or temperature differential. On the other hand, applying the chemical treatment with a surfactant while using a sonicator did improve the treatment’s efficiency. This thesis provides a number of factors to be considered when designing a chemical treatment and a guideline for further research in areas such as rate and extent of liquid chemical treatment penetration into fresh-cut produce.

Thèse de doctorat : Sciences de la vie et de la santé : Paris 12 : 2007. / Thèse électronique uniquement consultable au sein de l'Université Paris 12 (Intranet). Titre provenant de l'écran-titre. Bibliogr. : 318 réf.

In the sol gel production of high surface area catalyst, the template, a surfactant, is the key component of the process. A template too soluble in the supercritical dryingextraction process can yield a catalyst with a lower surface area. A template completely insoluble in the supercritical drying-extraction process can lead to a longer calcinations step and lower catalyst surface area. Template recovery also enhances the economic feasibility of plant scale production of high surface area catalyst. For these reasons knowing surfactant solubility in supercritical media is important. The solubility of surfactants tert-octylphenoxypolyethoxyethanol (commercially available and hereafter referred to as Triton X-114) and alkyloxypolyethyleneoxyethanol (commercially available and hereafter referred to as Tergitol 15-S-9) in supercritical carbon dioxide and ethanol entrainer have been determined at five-degree increments from 35 oC to 50oC. The solubility of the surfactants was determined by charging a variable volume cloud point system with the entrainer-surfactant mixture followed by liquid carbon dioxide. With the resulting stirred homogeneous mixture heated to temperature, cloud point pressures were observed as the phase analyzer cell was pressurized by adjusting the variable volume. An average of five values for cloud point pressure is reported here. The mixture behaviors were modeled using the Improved Rackett equation and the Peng-Robinson-Stryjek-Vera (PRSV) equation of state with Wong-Sandler (WS) mixing rules. For the Carbon Dioxide (CO 2) (1) – Ethanol/Triton X-114 (2) mixtures studied, compositions ranged from 93.2 mol% CO 2 to 97.7 mol% CO2. The solubility of Triton X-114 ranged from 0.02 mol% to 0.05 mol% at temperatures ranging from 35 oC to 50oC. Cloud point pressures observed for this system range from 95 bar to 143 bar. For the CO 2 (1) – Ethanol/Tergitol 15-S-9 (2) mixtures studied, compositions ranged from 92.3 mol% CO 2 to 94.4 mol % CO2. The solubility of Tergitol 15-S-9 ranged from 0.02 mol% to 0.03mol% at temperatures ranging from 35 oC to 50oC. Cloud point pressures observed for this system range from 89 to 154 bar.

The demand for energy and new oil reservoirs around the world has increased rapidly while oil recovery from depleted reservoirs has become more difficult. Oil production from fractured carbonate reservoirs by water flooding is often inefficient due to the commonly oil-wet nature of matrix rocks. Chemical enhanced oil recovery (EOR) processes such as surfactant-induced wettability alteration and interfacial tension reduction are required to decrease the residual oil saturation in matrix blocks, leading to incremental oil recovery. However, improvement in recovery will depend on the degree of wettability alteration and interfacial tension (IFT) reduction, which in turn are functions of matrix permeability, fracture intensity, temperature, pressure, and fluid properties. The oil recovery from fractured carbonate reservoirs is frequently considered to be dominated by the spontaneous imbibition mechanism which is a combination of viscous, capillary, and gravity forces. The primary purpose of this study is to model wettability alteration in the lab scale for both coreflood and imbibition cell tests using the chemical flooding reservoir simulator. The experimental recovery data for fractured carbonate rocks with different petrophysical properties were history-matched with UTCHEM, The University of Texas in-house compositional chemical flooding simulator, using a highly heterogeneous permeability distribution. Extensive simulation work demonstrates the validity and ranges of applicability of upscaled procedures, and also indicates the importance of viscous and capillary forces in larger fields. The results of this work will be useful for designing field-scale chemical EOR processes. / text

The depletion of oil reserves and higher oil prices has made chemical enhanced oil recovery (EOR) methods more attractive in recent years. Because of geological heterogeneity, unfavorable mobility ratio, and capillary forces, conventional oil recovery (including water flooding) leaves behind much oil in reservoir, often as much as 70% OOIP (original oil in place). Surfactant/polymer flooding targets these bypassed oil left after waterflood by reducing water mobility and oil/water interfacial tension. The complexity and uncertainty of reservoir characterization make the design and implementation of a robust and effective surfactant/polymer flooding to be quite challenging. Accurate numerical simulation prior to the field surfactant/polymer flooding is essential for a successful design and implementation of surfactant/polymer flooding. A recently developed unified polymer viscosity model was implemented into our existing polymer module within our in-house reservoir simulator, the Implicit Parallel Accurate Reservoir Simulator (IPARS). The new viscosity model is capable of simulating not only the Newtonian and shear-thinning rheology of polymer solution but also the shear-thickening behavior, which may occur near the wellbore with high injection rates when high molecular weight Partially Hydrolyzed Acrylamide (HPAM) polymers are injected. We have added a full capability of surfactant/polymer flooding to TRCHEM module of IPARS using a simplified but mechanistic and user-friendly approach for modeling surfactant/water/oil phase behavior. The features of surfactant module include: 1) surfactant component transport in porous media; 2) surfactant adsorption on the rock; 3) surfactant/oil/water phase behavior transitioned with salinity of Type II(-), Type III, and Type II(+) phase behaviors; 4) compositional microemulsion phase viscosity correlation and 5) relative permeabilities based on the trapping number. With the parallel capability of IPARS, commercial scale simulation of surfactant/polymer flooding becomes practical and affordable. Several numerical examples are presented in this dissertation. The results of surfactant/polymer flood are verified by comparing with the results obtained from UTCHEM, a three-dimensional chemical flood simulator developed at the University of Texas at Austin. The parallel capability and scalability are also demonstrated. / text