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2000

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Articles 91 - 110 of 110

Full-Text Articles in Chemical Engineering

Double-Slit Model For Partially Wetted Trickle Flow Hydrodynamics, I. Iliuta, F. Larachi, M. (Muthanna) H. Al-Dahhan Jan 2000

Double-Slit Model For Partially Wetted Trickle Flow Hydrodynamics, I. Iliuta, F. Larachi, M. (Muthanna) H. Al-Dahhan

Chemical and Biochemical Engineering Faculty Research & Creative Works

A Double-Slit Model Developed Can Predict the Frictional Two-Phase Pressure Drop, External Liquid Holdup, Pellet-Scale External Wetting Efficiency, and Gas - Liquid Interfacial Area in Cocurrent Downflow Trickle-Bed Reactors Operated under Partially Wetted Conditions in the Trickle Flow Regime. the Model, an Extension of the Holub Et Al. (1992, 1993) Mechanistic Pore-Scale Phenomenological Approach, Was Designed to Mimic the Actual Bed Void by Two Inclined and Interconnected Slits: Wet and Dry Slit. the External Wetting Efficiency is Linked to Both the Pressure Drop and External Liquid Holdup. the Model Also Predicts Gas - Liquid Interfacial Areas in Partially Wetted Conditions. …

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Studies On The Capacitance Of Nickel Oxide Films: Effect Of Heating Temperature And Electrolyte Concentration, Venkat Srinivasan, John W. Weidner Jan 2000

Studies On The Capacitance Of Nickel Oxide Films: Effect Of Heating Temperature And Electrolyte Concentration, Venkat Srinivasan, John W. Weidner

Faculty Publications

Nickel oxide films were prepared by electrochemically precipitating the hydroxide and heating it in air to form the oxide. The resulting oxide films behave as a capacitor. The capacitance of the oxide depends on the heating temperature, showing a maximum at 300°C. The mechanism of charge storage was studied by measuring the capacitance and surface area as a function of heating temperature, and the capacitance in different electrolytes and potential windows. The charge-storage mechanism is believed to be a surface redox reaction involving adsorbed hydroxyl ions.

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Development Of A New Electrodeposition Process For Plating Of Zn-Ni-X (X = Cd, P) Alloys: I. Corrosion Characteristics Of Zn-Ni-Cd Ternary Alloys, Anand Durairajan, Bala S. Haran, Ralph E. White, Branko N. Popov Jan 2000

Development Of A New Electrodeposition Process For Plating Of Zn-Ni-X (X = Cd, P) Alloys: I. Corrosion Characteristics Of Zn-Ni-Cd Ternary Alloys, Anand Durairajan, Bala S. Haran, Ralph E. White, Branko N. Popov

Faculty Publications

A new Zn-Ni-Cd plating process was developed which offers a unique way of controlling and optimizing the Ni and Cd contents in the final deposit. Zinc-nickel-cadmium alloy was deposited from a 0.5 M NiSO4 + 0.2 M ZnSO4 bath in the presence of 0.015 M CdSO4 and 1 g/L nonyl phenyl polyethylene oxide. Using this process a Zn-Ni-Cd ternary alloy, with a higher nickel content as compared to that obtained from conventional Zn-Ni baths, was synthesized. The Zn-Ni-Cd alloy coatings deposited from an electrolyte containing 0.015 M (0.3%) CdSO4 has a Zn to Ni ratio of …

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Ni-Composite Microencapsulated Graphite As The Negative Electrode In Lithium-Ion Batteries Ii: Electrochemical Impedance And Self-Discharge Studies, P. Yu, James A. Ritter, Ralph E. White, Branko N. Popov Jan 2000

Ni-Composite Microencapsulated Graphite As The Negative Electrode In Lithium-Ion Batteries Ii: Electrochemical Impedance And Self-Discharge Studies, P. Yu, James A. Ritter, Ralph E. White, Branko N. Popov

Faculty Publications

Electrochemical impedance and self-discharge studies were carried out to investigate lithium intercalation into bare and Ni-coated KS10 graphite. Values of the charge-transfer resistances, exchange current densities, surface film resistances, and lithium-ion diffusion coefficients as functions of the state of charge (SOC) all favored the 10 wt % Ni composite KS10 graphite over bare KS10 graphite when these materials were used as the negative electrode in a Li-ion cell with mixed organic electrolyte. The charge-transfer resistances were always lower and gave rise to between 26 and 27% larger exchange current densities, which increased from 137 to 614 mA/g as the SOC …

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A Semianalytical Method For Predicting Primary And Secondary Current Density Distributions: Linear And Nonlinear Boundary Conditions, Dhanwa Thirumalai, Ralph E. White Jan 2000

A Semianalytical Method For Predicting Primary And Secondary Current Density Distributions: Linear And Nonlinear Boundary Conditions, Dhanwa Thirumalai, Ralph E. White

Faculty Publications

No abstract provided.

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Development Of A New Electrodeposition Process For Plating Of Zn‐Ni‐X (X = Cd, P) Alloys: I. Corrosion Characteristics Of Zn‐Ni‐Cd Ternary Alloys, Anand Durairajan, Bala S. Haran, Ralph E. White, Branko Popov Jan 2000

Development Of A New Electrodeposition Process For Plating Of Zn‐Ni‐X (X = Cd, P) Alloys: I. Corrosion Characteristics Of Zn‐Ni‐Cd Ternary Alloys, Anand Durairajan, Bala S. Haran, Ralph E. White, Branko Popov

Faculty Publications

No abstract provided.

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Computational Fluid Dynamics Modeling Of A Lithium/Thionyl Chloride Battery With Electrolyte Flow, W. B. Gu, C. Y. Wang, John W. Weidner, Rudolph G. Jungst, Ganesan Nagasubramanian Jan 2000

Computational Fluid Dynamics Modeling Of A Lithium/Thionyl Chloride Battery With Electrolyte Flow, W. B. Gu, C. Y. Wang, John W. Weidner, Rudolph G. Jungst, Ganesan Nagasubramanian

Faculty Publications

A two-dimensional model is developed to simulate discharge of a lithium/thionyl chloride primary battery. As in earlier one-dimensional models, the model accounts for transport of species and charge, and electrode porosity variations and electrolyte flow induced by the volume reduction caused by electrochemical reactions. Numerical simulations are performed using a finite volume method of computational fluid dynamics. The predicted discharge curves for various temperatures show good agreement with published experimental data, and are essentially identical to results published for one-dimensional models. The detailed two-dimensional flow simulations show that the electrolyte is replenished from the cell head space predominantly through the …

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Development Of A New Electrodeposition Process For Plating Of Zn-Ni-X (X = Cd, P) Alloys: Permeation Characteristics Of Zn-Ni-Cd Ternary Alloys, A. Durairajan, B. S. Haran, Ralph E. White, Branko N. Popov Jan 2000

Development Of A New Electrodeposition Process For Plating Of Zn-Ni-X (X = Cd, P) Alloys: Permeation Characteristics Of Zn-Ni-Cd Ternary Alloys, A. Durairajan, B. S. Haran, Ralph E. White, Branko N. Popov

Faculty Publications

It is shown that an electrodeposited Zn-Ni-Cd alloy coating produced from sulfate electrolyte inhibits the discharge of hydrogen on carbon steel. The newly developed ternary alloys have approximately ten times higher corrosion resistance when compared to a Zn-Ni alloy. Hydrogen permeation characteristics of Zn-Ni-Cd alloy coatings were studied and compared with those of a bare and a Zn-Ni alloy coated steel. The transfer coefficient, a, exchange current density, io, thickness dependent adsorption-absorption rate constant, k0, recombination rate constant, k3, surface hydrogen coverage, θH, were obtained by applying a mathematical model to experimental results. Alloys obtained from baths containing higher concentration …

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Modeling Lithium Intercalation Of A Single Spinel Particle Under Potentiodynamic Control, Dong Zhang, Branko N. Popov, Ralph E. White Jan 2000

Modeling Lithium Intercalation Of A Single Spinel Particle Under Potentiodynamic Control, Dong Zhang, Branko N. Popov, Ralph E. White

Faculty Publications

A mathematical model is presented for the lithium intercalation of a single spinel particle as a microelectrode under the stimulus of a cyclic linear potential sweep. The model includes both lithium diffusion within the particle and kinetics at the particle/electrolyte interface. The model is used to predict that peak current densities depend linearly on the scan rate to a certain power with a constant term, which is different from the predicted peak current density for a conventional redox system.

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Shrinking Core Model For The Discharge Of A Metal Hydride Electrode, Venkat R. Subramanian, Harry J. Ploehn, Ralph E. White Jan 2000

Shrinking Core Model For The Discharge Of A Metal Hydride Electrode, Venkat R. Subramanian, Harry J. Ploehn, Ralph E. White

Faculty Publications

A shrinking core model is presented for the galvanostatic discharge of a metal hydride particle. A quantitative criterion for when the shrinking core can be completely neglected or approximated by a pseudosteady-state solution is presented. The effect of shrinking of the core on the discharge behavior of a metal hydride particle is also studied.

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Ethics Exercises For Civil, Environmental, And Geological Engineers, Paul Michael Santi Jan 2000

Ethics Exercises For Civil, Environmental, And Geological Engineers, Paul Michael Santi

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

The practices of civil, environmental, and geological engineering share many common ethical dilemmas. These fields typically require extensive interaction with clients and regulatory agencies, while dealing with unpredictable earth materials for design and uncertain design parameters. Consequently, a capstone design course must address not only technical issues, but also a wide range of ethical and behavioral issues. This study presents a series of exercises used in the classroom to teach these issues through dealing with "gray" ethical areas, concepts of advocacy and the use of compromise, relating specific stories to global concepts, proper behavior in the corporate environment, and the …

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Urea Hydrolysis Using Immobilized Urease, Anita Arullan Jan 2000

Urea Hydrolysis Using Immobilized Urease, Anita Arullan

Student Works (2000-2009)

An inexpensive carrier matrix. vermiculite was used for immobilizing urease. A cost effective and simple method of coupling was developed using vermiculite. Immobilization of urease on Amberlite MB-land Nylon-6 tube were also studied. Activities of free and immobilized urease were studied and compared: Among all methods used for immobilization of urease. the method of coupling the enzyme to vermiculite gave the highest retained activity of 82% (Method I) and 89% (Method 2) at pH 6.0 and 5.5 respectively. Urease immobilized by Method I retained 69% and 30% of its original activity and Method 2 (using glutaraldehyde as coupling agent) retained …

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Production Of 2,3-Butanediol From Molasses, Isita Sengupta Jan 2000

Production Of 2,3-Butanediol From Molasses, Isita Sengupta

Student Works (2000-2009)

2,3-Butanediol is an important chemical, which is used in the manufacture of products such as synthetic rubber, printing inks, perfumes, fumigants, moistening and softening agents, explosives and plasticizers. It has been known as a bacterial fermentation product since early part of the 20th century. Klebsiella oxytoca Is an organism, which can convert a variety of sugars to 2,3-butanediol. Available literature shows that principal monosaccharides of cellulosic substances as well as major hemicellulosic compounds have been used as carbon source. However, there is very little information on the application of waste material as carbon source for fermentation of butanediol. In this …

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Production Of Polyhydroaxyalkanoate (Pha) From Palm Oil By Pseudomonas Oleovorans And Indigenous Bacterial Isolate, Pseudomonas Sp., Zazali Alias Jan 2000

Production Of Polyhydroaxyalkanoate (Pha) From Palm Oil By Pseudomonas Oleovorans And Indigenous Bacterial Isolate, Pseudomonas Sp., Zazali Alias

Student Works (2000-2009)

In this study, the yield of biomass and polyhydroxyalkanoate  (PHA) of Pseudomonas oleovorans grown in batch and fed-batch cultivations were compared. When oleic acid (QA) (0.5% w/v) was used as carbon source, a significant increase in biomass.and PHA content were observed through fedbatch cultivation. The biomass and PHA content obtained from batch cultivation were 1.45±0.19 g/I and 2.50±0.77 % cell dry weight (CDW) respectively, while in the fed-batch cultivation, the biomass and PHA content increased significantly to 3.35±0.78 g/I and 32.72±0.30 %CDW respectively.  When saponified palm olein (SPO) (0.5% w/v) was used as a carbon source, the batch cultivation yielded …

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Ranking The Factors Impacting Lmmunosorbent Performance, Anuradha Subramanian, William H. Velander Jan 2000

Ranking The Factors Impacting Lmmunosorbent Performance, Anuradha Subramanian, William H. Velander

Papers in Biotechnology

This work addresses the relative impact of the phenomena of orientation, multipoint attachment, and local density of the immobilized antibody 011 immunosorbent perfornnance. The masking of the antigen binding domains of monoclonal antibodies (Mab) by Fab Masking Antigens (FMAs) was used as a tool to determine the impact of orientation on the perforn~anceo f Emphaze, Affiprep'M, and Cellulose bead-based immunosorbents. A two-step antibody immobilization inethod involving permeation of the beaded matrix followed by a fast coupling reaction was used to study the effect of local density of the Mnh on immunosorbent efficiency. Lysyl groups on Mabs were covalently modified to …

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Modeling High Pressure Char Oxidation Using Langmuir Kinetics With An Effectiveness Factor, Jianhui Hong, William C. Hecker, Thomas H. Fletcher Jan 2000

Modeling High Pressure Char Oxidation Using Langmuir Kinetics With An Effectiveness Factor, Jianhui Hong, William C. Hecker, Thomas H. Fletcher

Faculty Publications

The global nth order rate equation has been criticized for lack of theoretical basis and has been shown to be inadequate for modeling char oxidation rates as a function of total gas pressure. The simple Langmuir rate equation is believed to have more potential for modeling high pressure char oxidation. The intrinsic Langmuir rate equation is applied to graphite flake oxidation data and agrees well with reaction rates at three temperatures over the entire range of oxygen pressure (1–64 atm). It also explains the change of reaction order with temperature. In this work, the intrinsic Langmuir rate equation is combined …

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Modeling Nitrogen Evolution During Coal Pyrolysis Based On A Global Free-Radical Mechanism, Steven T. Perry, Thomas H. Fletcher Jan 2000

Modeling Nitrogen Evolution During Coal Pyrolysis Based On A Global Free-Radical Mechanism, Steven T. Perry, Thomas H. Fletcher

Faculty Publications

A global free-radical mechanism and an associated rate equation for the evolution of light gas nitrogen during coal devolatilization are presented. The light gas nitrogen rate equation was used to modify an existing nitrogen model so that only a network devolatilization model and coal-specific chemical structural input data are required to adequately predict light gas nitrogen release at a variety of pyrolysis conditions. Model predictions show good agreement with nitrogen release data from pyrolysis of coals of rank from lignite to low volatile bituminous at heating rates from 0.5 to 105 K/s, temperatures as high as 2300 K, and …

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Improving The Accuracy Of Predicting Effectiveness Factors For Mth Order And Langmuir Rate Equations In Spherical Coordinates, Jianhui Hong, William C. Hecker, Thomas H. Fletcher Jan 2000

Improving The Accuracy Of Predicting Effectiveness Factors For Mth Order And Langmuir Rate Equations In Spherical Coordinates, Jianhui Hong, William C. Hecker, Thomas H. Fletcher

Faculty Publications

Char oxidation is often modeled using an mth order intrinsic reaction rate in conjunction with an effectiveness factor to account for intraparticle diffusion of gas species. This approach involves the use of a general modulus (MT) and using the first-order curve of effectiveness factor vs MT. This method was originally referred to as the general asymptotic solution. It has been suggested that a simple Langmuir rate equation is more suitable for modeling the effects of pressure on char reactivity. Therefore, several methods of developing general moduli for the Langmuir rate expression are shown. The general asymptotic …

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The Use Of Two Mixture Fractions To Treat Coal Combustion Products In Turbulent Pulverized-Coal Flames, Daniel V. Flores, Thomas H. Fletcher Jan 2000

The Use Of Two Mixture Fractions To Treat Coal Combustion Products In Turbulent Pulverized-Coal Flames, Daniel V. Flores, Thomas H. Fletcher

Faculty Publications

Previous coal combustion models using assumed-shape PDF's to treat turbulence-chemistry interactions have used only one progress variable to treat products from coal reactions. This assumes that the products of all coal reactions have the same composition. However. the composition of the combustion products of coal particles is known to vary with burnout, especially between devclatilization and char oxidation. In this work, two progress variables were implemented which distinguish between the products of devolatilization and those of char oxidation. This new approach requires as input the specified volatile content and elemental release during devolatilization. The values for these parameters were estimated …

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Reconstitution And Characterization Of Membrane Proteins, Sarah Mia Pates Jan 2000

Reconstitution And Characterization Of Membrane Proteins, Sarah Mia Pates

Masters Theses

“A membrane protein, cytochrome c reductase, was crystallized and examined using transmission electron microscopy. Two-dimensional crystals were prepared by two methods. In Method 1, the protein was solubilized in 50 mM Tris-Acetate (pH 6.0)/0.5 mM EDTA70.05% (w/v) Triton X-100 and reconstituted into a mixture of phosphatidylcholine and phosphatidylserine (4:1), dissolved in the same buffer. The Triton X-100 was removed from the mixture by dialysis in the presence of Bio-beads (SM-2) at approximately 25-30 °C. Method 2 was the same as Method 1, except that the vesicles were fractionated before reconstitution, and the pH and temperature for crystallization were 7.0 and …

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