Chemical Engineering Commons^™

Thermotropic Liquid Crystalline Polyesters Based On The Monomer Of Poly(Ethylene Terephthalate), Satish Baliga

Dissertations

A series of thermotropic liquid crystalline polyesters were synthesized, based on Bis-hydroxyethyl terephthalate (BHET), para-acetoxybenzoic acid (PAB) and terephthalic acid (TA). Structural studies of these aromatic polyesters using Nuclear Magnetic Resonance (NMR), Infrared Spectroscopy (IR) and X-ray diffraction techniques indicated the existence of substantial amounts of rigid -PAB-PAB- linkages within the mesogenic backbone. Optical study of their melts using Polarizing Microscopy indicated a "threaded" microstructure typical of a nematic mesophase. Morphological rearrangements were found to occur at higher temperatures as was evident from a two-phase structure, one phase speculated to be rich in flexible Poly(ethylene Terephthalate) (PET) segments and the …

Kinetic Study On Pyrolysis Of C6h5cl And M-C6h4cl2 Diluted In H2 : Detailed Reaction Kinetics And Thermodynamic Property Estimation Techniques, Edward Robert Ritter

Dissertations

Thermal reaction studies of dilute mixtures (0.37%) of C6H5Cl in hydrogen and m-C6H4C12 (0.4%) in hydrogen have been performed in tubular flow reactors at various surface to volume ratios, and 1 atm total pressure. Residence times range from 0.02 to 2.5 seconds,with temperatures between 1050 to 1275 K. HCl, C₆H₅Cl, C₆H₆, and carbon solids (C(s)) are observed as the major products; minor products include methane, cyclopentadiene, toluene, naphthalene and biphenyls. Pyrolysis in helium yields significantly less conversion, but more C(s) for similar residence times.

A detailed chemical mechanism is developed to describe …

Gas-Phase Reactions Of Methylene Chloride And Methylene Chloride-Trichloroethylene Mixture With Methane In Tubular Flow Reactor And Atmospheric Pressure, Javad Tavakoli-Attar

Dissertations

Reactions of methylene chloride diluted in methane and Argon and a mixture of methylene chloride + trichloroethylene diluted in methane and argon are studied in three flow reactors of different surface to volume ratios 4, 10.5, and 16 mm ID , atmospheric pressure and over a temperature range of 750-1000 °C. Experiments were conducted isothermally, ±5 °C over central 80% of oven length using a three zone oven. Argon was added as a diluent in order to limit carbon (s) formation. The concentration ratios of methylene chloride/methane/argon and methylene chloride/trichloroethylene/methane/argon was held constant at 1:4:10 and 1:1:40:40 respectively, throughout the …

Reactor Design For Hazardous Waste Treatment Using A White Rot Fungus, Daewon Pak

Dissertations

Various nutrient media and reactor configurations have been explored in order to grow the white rot fungus Phanerochaete chrysosporium, induce its active enzyme, develop kinetic data for the degradation of 2-chlorophenol, and use chemical engineering analysis to design an efficient reactor.

Preliminary experiments indicated that the biodegradation rate was improved by two to three orders of magnitude when the fungus was immobilized. As a result, emphasis shifted to two types of reactor design: a packed-bed reactor employing a silica-based porous support, and a fluidized-bed reactor employing alginate beads. Both were very effective in degrading 2 chlorophenol at inlet concentrations up …

Transient Analysis Of Macromolecular Blood-Tissue Exchange In Microvascular Bed, Alex Yefim Bekker

Dissertations

Movement of macromolecules across microvascular walls was studied in the hamster cheek pouch with intravital fluorescence microscopy. A graded series of Fluorescein Isothiocyanate labeled Dextrans(FITC) of 20,000 -70,000 molecular weight were used as representative macromolecular tracers. The time dependent extravasation of FITC-Dextrans was video taped for approximately two and a half hours. Permeation of macromolecules from individual microvessels was quantified by digital video image processing. Histograms of the light intensity distributions for selected fields at various times have been measured and used to construct integral optical density - time profiles of the extravasated fluorochromes for particular leaky sites. An integrated …

The Use Of Pure Cultures As A Means Of Understanding The Performance Of A Mixed Culture In The Biodegradation Of Phenol, Chirasakdi Varuntanya

Dissertations

In an effort to gain a more fundamental understanding of the performance of mixed microbial cultures in the biodegradation of toxic organic chemicals, studies have been conducted using three phenol degrading species isolated from a municipal treatment plant. The rate of phenol degradation was investigated for each of the three pure phenol degrading species, and various combinations of the three species. A simple competitive model was used to predict the behavior of the mixed cultures by using the pure culture Monod rate constants. The model fit the growth data for total biomass very well, although (as with the pure culture …

Fluid Flow And Gas Absorption In An Ejector Venturi Scrubber, Iclal Atay

Dissertations

Empirical models were developed to describe the fluid flow characteristics and gas absorption efficiency of an ejector venturi scrubber. The empirical constants were determined experimentally using stop action photographs of the spray, static pressure measurements, and sulfur dioxide absorption efficiencies.

To take photographs of the spray, a 2 foot high, clear plastic ejector venturi scrubber was used, with a 4 inch diameter gas entrance port. Photographic equipment included a Hasselblad camera, Xenon flash lamp, and Polaroid 667 ASA 3000 film. Exposure duration was about 1 microsecond, resulting in complete stop-action of the spray droplets at liquid rates up to 6 …

Reactions Of Chlorocarbon Species With Hydrogen Over Palladium On Alumina Catalyst And Zeolite Catalyst-Development Of Deactivation Models, Yuh-Der Yang

Dissertations

Four catalytic dechlorination reactions were studied experimentally using a fixed-bed reactor at atmosphere pressure. Reaction mechanisms were proposed, and the kinetics modelled.

The first reaction is 1,2-dichloroethane with hydrogen over zeolite catalyst. Catalyst deactivation models were examined.

The second reaction was between 1,2-dichloroethane and hydrogen over palladium catalyst on alumina support. Formation of two intermediates on the catalyst surface is proposed, which then produced ethane, ethylene, and ethyl chloride. Higher conversion to ethane and ethylene was observed at temperatures above 218°C while conversion to chloroethane is higher at temperatures below 218°C. The activation energy was found to be 15 Kcal/gm-mole. …

An Industrial Ethanol Azeotropic Distillation Process : Modeling, Analysis, And Simulation, Harpreet Singh Chawla

Dissertations

A steady state process simulator with extensive capabilities was developed for the simulation of process plants involving non-ideal multicomponent systems. A comprehensive stand alone program was developed to represent process systems encountering three phases. A computer program was also developed to handle simultaneous regression of vapor-liquid and liquid-liquid equilibria data to estimate the liquid phase activity coefficients via a global set of parameters for the ethanol azeotropic distillation process, using benzene as the entrainer.

An industrial ethanol azeotropic distillation process has been simulated using the developed process simulator (PROSIM). A study of the azeotropic column's aqueous ethanol feed composition reveals …

The Effect Of Single Electrolytes On The Vapor-Liquid Equilibrium Of Mixed Solvents, Peggy Tomasula

Dissertations

A group-contribution model for the prediction of salt-effects on the vapor-liquid equilibria of multicomponent electrolytic solutions containing a single electrolyte is presented. Coulombic interactions are represented through a Pitzer term. Solvation effects and short-range interactions are represented through a UNIQUAC-type expression. An ion-size, a solvation and three ion-solvent interaction parameters per salt-solvent binary are required for multicomponent predictions.

All parameters are obtained only through the correlation of binary salt-solvent osmotic coefficient and vapor-pressure depression data at 25°C, in most cases, and binary solvent VLE data. The salt-solvent binary data were correlated with an average percent error in CD of 2.5 …

Ternary Ion Exchange In Fixed Beds : Equilibrium And Dynamics, David W. H. Roth

Dissertations

A model was developed to simulate ion exchange within fixed beds for ternary systems. Models of the fluid phase material balance, phase equilibria, and diffusion of ions through the film and within the resin phase incorporated the latest advances in ion exchange theory. The separate model elements were combined after testing into an overall general model. Non-linear regression support programs were developed to estimate equilibrium parameters and resin phase diffusion coefficients.

A computer program was developed to estimate axial dispersion coefficients from experimental data. General correlations derived from literature sources were tested, and axial dispersion terms were included in the …

Kinetic Modeling Of A Laminar-Flow Reactor, Shih-Hsin Chang

Dissertations

The laminar-flow reactor considering radial dispersion for a species incurring first-order homogeneous (bulk) and heterogeneous (wall) chemical reactions was mathematically modeled. The equation was solved both analytically, and by the Crank-Nicolson finite-difference technique.

The response surface method was used to obtain the optimum values of the two rate constants. The optimum values interact because the wall and bulk reactions proceed in parallel. Varied reactor diameters serve to decouple the bulk and wall reactions to locate the true values of the rate constants.

Four dimensionless variables were defined and used to characterize the reacting system. In addition, their values were shown …

Mathematical Simulation Of Proteins Separation In A Packed Bed, Jing James Huang

Dissertations

The generalized adsorption models are developed to simulate the unsteady state mass transfer behavior in a packed column. Based on the nature of adsorbent particles, the adsorption models may be classified into two categories: (1) the surface adsorption model, (2) the pore diffusion model. In the first model, it is assumed that the internal diffusion is negligible, and the adsorption rate is determined by external diffusion and surface adsorption. In the second model, the effect of internal diffusion is considered as significant as that of external diffusion. For both models, the effect of axial dispersion in fluid phase is emphasized. …

Mathematical Modeling Of Carrier Mediated Mass Transfer Through Liquid Membrane Systems, Keng Chao Wang

Dissertations

Dispersed liquid membrane systems are double emulsion drops. Two immiscible phases are separated by a third phase which is immiscible with the other two phases. The liquid membrane systems were classified into three types: (1) carrier mediated mass transfer, (2) mass transfer with reaction in the receiving phase, (3) mass transfer without any reaction involved. Copper extraction, phenol removal and solvent extraction were used as typical examples for each type of the membrane systems in the derivation of their mathematical models. Models with or without the consideration of film resistances were developed and compared. The models developed in this study …

Mixing Effect On Chemical Reaction In Liquid Phase, Ming-Teh Hsu

Dissertations

Mathematical models for the mixing phenomenon are proposed in this study. First model deals Newtonian and non-Newtonian fluid without chemical reaction. The new terminology " degree of mixing " is define in this model for the time-dependency of mixing toward its completeness. The velocity profile and boundary conditions are given, then the degree of mixing can be calculated by the mathematical model. The degree of mixing is influenced by fluid motion and it is function of time.

Second model deals with first-order reaction effected by mixing. A mean fractional conversion is defined to investigate the rate of bhemical reaction. Results …

Mathematical Modeling Of Unsteady State Photo-Polymerization, Rong-Fa Liang

Dissertations

Mathematical modeling of unsteady state photopolymerization in an isothermal batch reactor has been investigated. An analytical solution of the distribution of active polymers as a function of reaction time has been determined. It is verified that the quasi-stationary state approximation is valid in the photopolymerization process.

The free radical polymerization of styrene is forced periodically by on-off UV light regulation to the reactor. The effect of operating condition, the ratio of light-off period to light on/off period, on the polydispersity and molecular weight distribution are theoretically and numerically investigated. Significant broadening on molecular weight distribution can be obtained during the …

Mathematical Modeling Of Distillation Operation From Non-Equilibrium Approach, Wen-Dow Pan

Dissertations

A new method for mathematical modeling of a distillation operation from non-equilibrium approach has been studied. The primary purpose of the study was to develop a model to simulate the mechanism of mass transfer between a continuous phase and the bubbles of a dispersed phase in a distillation column. The second major purpose of this work was to utilize and test the model of estimating the tray efficiency.

Distillation was considered to be purely a mass transfer process, where the less volatile component is transferred from vapor to liquid phase, and the more volatile component from liquid to vapor phase. …

Use Of An Optical Probe To Measure Bubble Characteristics In Gas Fluidized Beds, Thomas Tai-Pai Chu

Dissertations

A novel optical probe has been developed and used for on-line monitoring of the bubble characteristics in a three-dimensional gas fluidized bed. The probe sensor has a major dimension of 1.8 cm, and contains an LED and a photo-cell separated by a gap of 2.5 mm. Coupled with a non-inverting comparator circuit with hysteresis as a noise filter, the probe has been very effective in characterizing the size distribution, shape and velocity of gas bubbles.

A 96 liter rectangular fluidized bed was used, containing glass beads with a size fraction of 355μ to 250μ. Air was the fluidizing medium, with …

Mathematical Models Of Unsteady Operation Of A Packed Column, Jen-Fu Chao

Dissertations

Analytical solutions of differential equations applicable to extraction, ion exchange, or adsorption processes in packed beds are presented. Results are given for three different cases. The first case accounts for adsorption phenomena only. The second one includes surface adsorption on particles and the effects of longitudinal dispersion in the bed. The third one deals with diffusion in particles and longitudinal dispersion in the bed. In the mathematical modelling of these three cases, a linear equilibrium relationship between the solute in the liquid phase and solute in the solid phase is used. The first case is solved using the single boundary …

The Settling Of An Arbitrary Number Of Spherical Particles Arranged On The Corners Of A Regular Polygon In A Viscous Fluid, Eric Robert Bixon

Dissertations

The creeping motion equation has been solved for the case of planar arrays of spheres settling under the influence of gravity in a viscous fluid. The solution is a general solution which applies to an arbitrary number of spheres. All particles will lie at the corners of a regular polygon. Thus, two particles side by side, three particles in an equilateral triangular array, or four spheres in a square array will be special cases of the general solution.

The solution has been obtained by a unique application of the method of reflections. Only a first correction to the drag has …

The Effect Of Ultrasound On The Hydrolysis Of Carbohydrates, Adel A. Khamis

Dissertations

Acid hydrolysis of dextran and cellulose were studied with and without irradiation with ultrasonic waves of different frequencies (17 - 150 KHz), and powers (0.4 - 200 w/cm²). In the case of both materials, the hydrolysis reaction was found to be first order with respect to the activity of hydrogen ions in the reaction medium. Weight average molecular weight was evaluated at different durations of the reaction course. The reaction rate of dextran was found to be proportional to the weight average molecular weight raised to the power 4/3, and raised to the power 4 for cellulose.

The …

Motion Of Viscous Liquid In Rotating Cylinder, Chicheng Wu

Dissertations

A computer model for the withdrawl and buildup of the fluid from the pool bounded on the horizontal, rotating, cylindrical surface has been developed. For a incompressible Newtonian fluid, the model is based upon the modified SOLA-SURF algorithm to solve the finite-difference form of Navier-Stokes equations on primitive variables. A hybird of centered and partial donor cell differencings is applied to the momentum convective flux. In each time cycle, the cell velocity is adjusted by the pressure corrector and iterates to satisfy the equation of continuity. The free surface position is approximated by a surface height function derived from kinematic …

Fractionation Of Multicomponent Mixtures By Staged Sequence Cyclic Process And Parametric Pumping, Charles Omotayo Kerobo

Dissertations

The continuous fractionation of multicomponent fluid mixtures has been experimentally and theoretically investigated by staged sequence cyclic process and parametric pumping operating in the direct thermal mode.

A multicolumn staged sequence cyclic process for the separation of solute mixtures was developed. The criteria necessary for the continuous fractionation of a system of n solutes with n+1 columns arranged in a series operated with n+1 cyclic variables is presented. The feasibility for practical application of this process was demonstrated by fractionating the model system, O-xylene-Anisole-n-heptane on silica gel. The separation was modeled by one column staged sequence experimental data and by …

Separation Of Proteins Via Ph Parametric Pumping With Electric Field, Helen Conway Hollein

Dissertations

A new semi-continuous parametric pumping process for the separation of protein mixtures has been developed, based on cyclic variation of pH and electric field. The model system used for this process consisted of a mixture of human serum albumin and human hemoglobin in contact with CM Sepharose cation exchanger. Experimental results show that the protein separation via the pH parapump with electric field is two to three times greater than the results which are obtained in batch chromatography or via either single-column or multi-column parapumps with cyclic variation of pH and ionic strength.

The separation in the new process depends …

An Experimental Study Of Multiple Steady States In A Photopolymerization Reactor, Chih-Ning Kuan

Dissertations

An experimental study of photosensitized free radical polymerization of styrene in both batch and continuous stirred tank reactors is presented. Each reactor was run under both adiabatic and isothermal conditions. Multiple steady states were investigated. Exact multiplicity and uniqueness criteria for the above systems were derived and a mathematical model developed to correlate the results.

For both adiabatic and isothermal continuous stirred tank reactors operating in the metastable state regions, the conversion and polymer molecular weight are greater than the corresponding lower steady state operations. At a given conversion level, the reaction time for both adiabatic and isothermal continuous stirred …

The Entrainer Effect On Azeotropic Distillation Column Design, Charles Ming-Hsiao Tsai

Dissertations

A rigorous multistage distillation model was developed for use with non-ideal multicomponent systems. A subsidiary computer program was also developed to handle the problem of two liquid phases after condensation of a vapor.

Using the program developed, entrainer entry location and rate effects have been investigated via computer simulation for azeotropic distillation columns. The specific example used to verify the procedure was an ethanol dehydration column using benzene as the entrainer. The results indicate that the entrainer should enter the column two to five theoretical stages above the feed. The optimum entrainer rate was also determined.

The overhead vapor product …

Separation Technique On Proteins Via A Ph-Parametric Pump : A Theoretical And Experimental Study, Ura Pancharoen

Dissertations

The separation of protein mixtures via pH-parametric pumping was investigated both theoretically and experimentally. A simple system consisting of one column packed either with cation or anion exchanger was first considered. A system of parapumps was then developed with more columns which were connected in series and packed alternately with cation and anion exchangers. Various methods of operation of parapumps are discussed. Enrichment and spliting of protein mixtures were examined. In most cases, the separation factor was defined at a steady state condition and was improved by increasing the number of cycles and columns.

Computational methods for predicting both Batch …

Correlation And Prediction Of Vapor-Liquid Equilibrium In Electrolytic Solutions, Anil Krishna Rastogi

Dissertations

Two expressions for the excess Gibbs free energy are presented which correlate and predict vapor-liquid equilibrium and the mean molal activity coefficient of an electrolyte in a ternary mixture containing water and either MeOH or EtOH. The proposed equations take into account coulombic forces between ions and the physical interaction forces between ion-solvent and solvent-solvent molecules in a solution.

Model #1 is a combination of an extended Debye and Huckel equation and the local composition of non-random two liquid (NRTL) model. A ternary mixture requires six adjustable binary parameters to predict activity coefficients. These six parameters are evaluated from three …

Separation Of Proteins Via Continuous Ph Parametric Pumping, Steve Wu

Dissertations

This dissertation covers the separation of proteins via recuperative mode pH parametric pumping. Continuous pH parametric pumping separations using the model system haemoglobin and albumin on a CM-Sepharose cation exchanger have been experimentally and theoretically investigated.

The pH parametric pumping system has a feed containing the protein mixture to be separated, introduced alternately to the top and bottom of the column. The top and bottom products are withdrawn from the apparatus during the bottom and top feed, respectively. Both equilibrium and nonequilibrium cases were considered, and theoretical results agreed with the experimental data.

Buffer concentration, flow rate, reservoir displacement, and …

Parametric Pumping With Ph And Ionic Strength : Enzyme Purification, Zikri Mostafa Ahmed

Dissertations

The work on separation and purification of proteins by parametric pumping has been restricted so far to pH parametric pumping where the difference between the iso-electric points of the components to be separated is apparent. The present work establishes the foundations for the continuous separation and purification of proteins (including enzyms) that have similar or very close iso-electric points by using the ionic strength as a driving force for the separation process. This technique has commercial advantages over batch processes.

It was found that the most promising technique for separating alkaline phosphatase consists of the following three major steps: (I) …