Chemical Engineering Commons^™

Investigation And Synthesis Of Novel Graphene-Based Nanocomposites For Hydrogen Storage, Anthony Joseph D'Angelo

USF Tampa Graduate Theses and Dissertations

It is of great interest to develop and utilize a high surface area material with optimized hydrogen sorption properties. The need for a renewable energy source to replace automobile gasoline has become more critical in the past decade. Hydrogen is a viable fuel source for automobile usage; however, the question of how hydrogen will be safely and efficiently stored still remains. Critical factors for optimum hydrogen storage include ambient conditions and low activation temperature for adsorption and desorption phenomena. In order for optimum hydrogen adsorption to be achieved, the properties of (1) high surface area, (2) optimum hydrogen adsorption energy, …

Temperature Dependent Droplet Impact Dynamics On Flat And Textured Surfaces, Azar Alizadeh, Vaibhav Bahadur, Sheng Zhong, Wen Shang, Ri Li, James Ruud, Masako Yamada, Liehui Ge, Ali Dhinojwala, Manohar Sohal

College of Polymer Science and Polymer Engineering

Droplet impact dynamics determines the performance of surfaces used in many applications such as anti-icing, condensation, boiling, and heat transfer. We study impact dynamics of water droplets on surfaces with chemistry/texture ranging from hydrophilic to superhydrophobic and across a temperature range spanning below freezing to near boiling conditions. Droplet retraction shows very strong temperature dependence especially on hydrophilic surfaces; it is seen that lower substrate temperatures lead to lesser retraction. Physics-based analyses show that the increased viscosity associated with lower temperatures combined with an increased work of adhesion can explain the decreased retraction. The present findings serve as a starting …

Effect Of Platinum Particle Size On The Sulfur Deactivation Of Hydrogenation, Lyndsey Michelle Baldyga

USF Tampa Graduate Theses and Dissertations

A large concern of the fossil fuel and renewable energy industries is the sulfur poisoning of catalysts. In the case of noble metals, such as platinum, it is seen that there is a size trend associated with the level of activity in the presence of sulfur. Smaller nanoparticles could be more tolerant due to sulfur surface vacancies. On the other hand, larger particles could have less deactivation because the sulfur is more attracted to the smaller particles and the sulfur molecules bind stronger to these smaller particles.

The size effect of sulfur deactivation was investigated by testing four sizes of …

A Streamlined Strategy For Biohydrogen Production With Halanaerobium Hydrogeniformans, An Alkaliphilic Bacterium, Matthew B. Begemann, Melanie R. Mormile, Oliver C. Sitton, Judy D. Wall, Dwayne A. Elias

Biological Sciences Faculty Research & Creative Works

Biofuels are anticipated to enable a shift from fossil fuels for renewable transportation and manufacturing fuels, with biohydrogen considered attractive since it could offer the largest reduction of global carbon budgets. Currently, lignocellulosic biohydrogen production remains inefficient with pretreatments that are heavily fossil fuel-dependent. However, bacteria using alkali-treated biomass could streamline biofuel production while reducing costs and fossil fuel needs. An alkaliphilic bacterium, Halanaerobium hydrogeniformans, is described that is capable of biohydrogen production at levels rivaling neutrophilic strains, but at pH 11 and hypersaline conditions. H. hydrogeniformans ferments a variety of 5-and 6-carbon sugars derived from hemicellulose and cellulose …

Biomedical Properties And Preparation Of Iron Oxide-Dextran Nanostructures By Maple Technique, Carmen Steluta Ciobanu, Simona Liliana Iconaru, Eniko Gyorgy, Mihaela Radu, Marieta Costache, Anca Dinischiotu, Philippe Le Coustumer, Khalid Lafdi, Daniela Predoi

Chemical and Materials Engineering Faculty Publications

Background: In this work the chemical structure of dextran-iron oxide thin films was reported. The films were obtained by MAPLE technique from composite targets containing 10 wt. % dextran with 1 and 5 wt.% iron oxide nanoparticles (IONPs). The IONPs were synthesized by co-precipitation method. A KrF* excimer laser source (λ = 248 nm, τFWHM≅25 ns, ν = 10 Hz) was used for the growth of the hybrid, iron oxide NPs-dextran thin films.

Results: Dextran coated iron oxide nanoparticles thin films were indexed into the spinel cubic lattice with a lattice parameter of 8.36 Å. The particle sized calculated was …

Effects Of Adding Acid Plant Sulfur On Heap Leaching, Jibin George

Masters Theses and Doctoral Dissertations

Mining industry is heavily invested in mining various precious metals from their natural ore deposits. Copper ore deposits are found across the world and heap leaching of copper has been implemented effectively for years. The ore is broken down to copper ions and elemental sulfur in the heap. Acid plants are used in mines to replenish the raffinate leaching the heaps which consists of sulfuric acid. Molten sulfur carried in rail cars to the acid plant is often accidentally spilled on the ground. The contaminated sulfur cannot be added to the acid plant and has been disposed of as hazardous …

Synthesis And Electrochemical Performance Of Xlifepo4·Yli3V2(Po4)3 Composites, Ping-Ping Ma, Zhi-Jian Liu, Jian-Hua Xia, Yu Chen, Pu Hu, Zhi-Chao Lu, Ding-Guo Xia

Journal of Electrochemistry

A series of xLiFePO₄·yLi₃V₂(PO₄)₃ composites were systematically synthesized through solid state reactions by variations in the proportions of LiFePO₄ and Li₃V₂(PO₄)₃. The properties of the prepared compounds were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM) and electrochemical measurements. The capacity of 162.7 mAh/g at 0.2 C rate was obtained with the relatively good cycle stability and good conductivity for 0.95LiFePO₄·0.05Li₃V₂(PO₄)₃ due to more uniformed distributed and smaller particle sizes.

Electrocatalytic Study Of Pseudomonas Aeruginosa Bte-1 Strain, Ping Zhou, En-Ren Zhang, Li Zhou, Guo-Wang Diao, Jun-Le Niu

Journal of Electrochemistry

The aim of the present study is to investigate the electrocatalytic activity of electricity-producing Pseudomonas aeruginosa BTE-1 strain under anaerobic conditions. Pseudomonas aeruginosa BTE-1 was inoculated into anaerobic three-electrode electrochemical cells, and the electrocatalytic activity was measured at poised potentials. HPLC and cyclic voltammetry were used to detect potential electron mediators in solutions. Experimental results showed that no detectable pyocyanine was excreted by P. aeruginosa BTE-1 strain in the anaerobic electrochemcial cells, and P. aeruginosa BTE-1 exhibited direct electrocatalytic activity through the formation of biofilm on the electrode surface which was induced by the electron transfer from the cells of …

Progress And Perspective Of Fuel Cell Technology, Ming Hou, Bao-Lian Yi

Journal of Electrochemistry

Fuel cell, a clean and high-efficiency electrochemical power source, has being paid much attention worldwide recent years. In this paper, the progress and perspective of fuel cell technology are elucidated in detail. Fuel cells have been applied in some special fields such as spacecraft, shuttle and submarines. However, in the areas of transportation, stationary station and portable power source, fuel cells are still under demonstration due to the durability and cost problems. The reliability and surrounding survivability of fuel cells should be enhanced in the special application. Meanwhile, the durability and cost of fuel cells are the main issues to …

Impact Of Internals On The Heat-Transfer Coefficient In A Bubble Column, Rahman S. Abdulmohsin, Muthanna H. Al-Dahhan

Chemical and Biochemical Engineering Faculty Research & Creative Works

The Effect of Heat Exchanging Internals on the Heat-Transfer Coefficient Has Been Investigated in a 0.19 M Diameter Bubble Column. an Air-Water System Was Used with Superficial Gas Velocities Varying from 3 to 20 Cm/s, Which Cover Both the Bubbly and Churn-Turbulent Flow Regimes. Internals Occluding 0% (Empty Column), 5% (Simulating Methanol Synthesis), and 22% (Simulating Fischer-Tropsch Synthesis) of the Column Cross-Sectional Area Were Implemented. a Fast Response Heat-Transfer Probe Was Utilized to Measure the Radial Profile of the Heat-Transfer Coefficient in the Fully Developed Flow Region. the Results Indicate that the Presence of a High Percentage of Internals Causes …

Influence Of Solid-Phase Wall Boundary Condition On Cfd Simulation Of Spouted Beds, Xingying Lan, Chunming Xu, Jinsen Gao, Muthanna H. Al-Dahhan

Chemical and Biochemical Engineering Faculty Research & Creative Works

The Influence of Solid-Phase Wall Boundary Condition in Terms of Specularity Coefficient and Particle-Wall Restitution Coefficient on the Flow Behavior of Spouted Beds Was Investigated using Two-Fluid Model Approach in the Computational Fluid Dynamics Software FLUENT 6.3. Parametric Studies of Specularity Coefficient and Particle-Wall Restitution Coefficient Were Performed to Evaluate their Effects on the Flow Hydrodynamics in Terms of Fountain Height, Spout Diameter, Pressure Drop, Local Voidage and Particles Velocity. the Numerical Predictions Were Compared with Available Experimental Data in the Literatures to Obtain the Suitable Values of Specularity Coefficient and Particle-Wall Restitution Coefficient for Spouted Beds. the Simulated Results …

Nanostructured Catalyst Materials For Next Generation Polymer Electrolyte Membrane (Pem) Fuel Cells, Wisam J. Khudhayer

Theses and Dissertations

Polymer electrolyte membrane (PEM) fuel cells are electrochemical energy conversion devices which have demonstrated great promise as future energy sources for electric vehicles, as they convert chemical energy to electrical energy with a significantly higher efficiency and lower environmental impact than in standard combustion processes. However, the commercialization of PEM fuel cells for transportation applications has been hindered by several factors such as high cost of Pt, low Pt utilization, poor long-term durability of the conventional PEM fuel cell catalyst (Pt nanoparticels supported on carbon black, Pt/C), and poor thermal and chemical stability of the electrocatalyst supports (carbon black). The …

Carbon Nanotubes Grown On Glass Fiber As A Strain Sensor For Real Time Structural Health Monitoring, Matthew Boehle, Qiong Jiang, Lingchuan Li, Alexandre Lagounov, Khalid Lafdi

Chemical and Materials Engineering Faculty Publications

In order to more effectively monitor the health of composite structures, a fuzzy fiber sensor has been developed. The fuzzy fiber is a bundle of glass fibers with carbon nanotubes or nanofibers (CNTs or CNFs) grown on the surface. The nanotube coating makes the fiber bundle conductive while the small conductive path increases sensitivity. The fuzzy fiber sensor can replace conventional metal foil strain gauges in composite applications. The electrical response of the sensor is monitored in real time to measure strain, vibration, cracking and delamination. Continuous monitoring provides instant notification of any problems. Implementation of this sensor network in …

Heat Transfer Coefficients In Mimicked Fischer-Tropsch Slurry Bubble Columns, Chengtian Wu, Muthanna H. Al-Dahhan

Chemical and Biochemical Engineering Faculty Research & Creative Works

To Provide More Support for Fischer-Tropsch (FT) Slurry Bubble Column Reactor Design, Scale-Up, and Performance, the Effects of Operating Conditions on the Heat Transfer Coefficients Were Investigated in a Mimicked FT Cold Flow System (Compressed Air:C 9-C 11:FT Catalyst Carrier). the Studied Operating Conditions Varied in Superficial Gas Velocity (Up to 0.3 M/s), Pressure (Up to 10 Bar), and Solids Concentration (Up to 25 Vol %). the Effects of These Variables on Heat Transfer Coefficients Are Discussed and Analyzed. the Increase in Pressure Tended to Reduce the Heat Transfer Coefficient, While the Increase in Solids Loading Enhanced the Heat Transfer …

Generalized Ellipsometry In-Situ Quantification Of Organic Adsorbate Attachment Within Slanted Columnar Thin Films, Keith B. Rodenhausen Jr., Daniel Schmidt, Tadas Kasputis, Angela K. Pannier, Eva Schubert, Mathias Schubert

Department of Chemical and Biomolecular Engineering: Faculty Publications

We apply generalized ellipsometry, well-known to be sensitive to the optical properties of anisotropic materials, to determine the amount of fibronectin protein that adsorbs onto a Ti slanted columnar thin film from solution. We find that the anisotropic optical properties of the thin film change upon organic adsorption. An optical model for ellipsometry data analysis incorporates an anisotropic Bruggeman effective medium approximation. We find that differences in experimental data from before and after fibronectin adsorption can be solely attributable to the uptake of fibronectin within the slanted columnar thin film. Simultaneous, in-situ generalized ellipsometry and quartz crystal microbalance measurements show …

Single And Multiphase Mixing In Partially Filled Stirred Vessels, Shilan Motamedvaziri

Dissertations

In many industrial applications, mixing vessels have a liquid height-to-tank diameter ratio, H/T, equal to, or larger than 1. However, there are many instances where this ratio is lower than 1, as in all those cases in which the vessel is either emptied or filled. Even when H/T<1, sufficient agitation must still be provided in order to attain the desired process objectives. When the impeller submergence is reduced as a result of lowering the liquid level, the fluid dynamics of even a single-phase stirred liquid can become quite complex, with different regimes possibly existing depending on the geometric characteristics of the system (such as impeller clearance, liquid height, or liquid submergence above the impeller). The objectives of this work were to study in detail the hydrodynamic changes that occur when H/T is decreased, and to determine the minimum liquid levels and the critical impeller submergence for different impeller off-bottom distances, impeller diameters and agitation speeds where adequate mixing process can still be achieved, both in a single liquid phase and in solid-liquid suspensions.

Flat-bottomed, baffled vessels (5L, 12L, 20L and 170L) equipped with a single disk turbine (DT) of four different sizes placed at five different impeller off-bottom clearances were used here to study the system's hydrodynamics and related mixing phenomena. A number of experimental tools were used to analyze the systems under investigation, including: …

Hot-Melt Mixing Of Partially Miscible Active Pharmaceutical Ingredient-Polymer Mixtures, Min Yang

Dissertations

Solid dispersion/solution processes for producing pharmaceutical oral dosages such as hot-met extrusion (HME) have received increasing attention by industry and academe because they can enhance drugs’ solubility and even bioavailability to a great extent by converting drugs from crystalline to amorphous form. HME can be carried out at two process temperature regimes: one where T_process > T_m of the drug and the T_g of the polymer (or the T_m for the case of semi-crystalline polymers); the other at T_m > T_process > T_g (T_m for the case of semi-crystalline polymer). Processing below the drug’s …

Combustion Dynamics Of Individual Reactive Material Particles, Carlo Francisco Badiola

Theses

Metallic reactive powders are widely used as solid fuels, pyrotechnic materials, and components of enhanced blast explosives. Metals are attractive because of their high combustion enthalpies and temperatures. Quantitative descriptions of the combustion processes and mechanisms for both pure metal and composite particles are also desired for their proper implementation in specific applications. Among reactive metals, Al is used most widely and its combustion has been studied extensively. A recently developed experimental setup using laser-ignited metal powders enabled one to record optical signatures for time-resolved combustion instances for 2-25 µm diameter aluminum particles burning in different atmospheres. Individual particle diameters …

Preparation Of Different Polyamide Nanofiltration Membranes By Interfacial Polymerization And The Effect Of Post-Polymerization Treatment On Separation Performance, Yu Qin

Theses

Interfacial polymerization (IP) is a powerful technique for fabrication of thin film composite (TFC) membranes. In this study, polyamide nanofiltration (NF) composite membranes ware prepared by interfacial polymerization of polyethylenimine (PEI) or m-phenylene diamine (MPD) with isophthaloyl dichloride (IPD) on the surface of a porous polyethersulfone (PES) support. Concentrations of monomer reactants for this reaction were decided by equivalent weight ratio. A standard IP procedure was applied to successfully coat PES flat films. After preparation, three different post-polymerization treatments were employed and one optimal treatment was proven after membrane testing.

The TFC flat film membranes were characterized by nanofiltration of …

Carbon Dioxide Transfer Through Hollow Fiber Membranes, Pavlo Kostetskyy

Theses and Dissertations

Studies on absorption of CO2 into an aqueous solution using hydrophobic microporous hollow fiber membranes (HFM's) were performed. The use of HFM's for CO2 transfer could significantly improve the biomass growth rate in a photobioreactor for algal biofuel production. The membrane modules were operated in a sealed-end, parallel flow configuration. Several modules were constructed that ranged in interfacial surface area from 466 to 1397 m2/m3. The mass transfer coefficients were calculated based on a model of the system that included a prediction of the internal axial gas concentrations within the fiber lumen. This model was validated by measuring bulk gas …