Chemical Engineering Commons^™

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) …

Separation Via Multi-Column Ph Parametric Pumping, Wei Tai Yang

Dissertations

This thesis presents the study of multi-column pH parametric pumping, a separation technique which applies the principle of parametric pumping and uses pH as control variable. Studies emphasize the mass transfer and the capability of separation by multi-column pH parametric pumping. Many operation modes of multi-column pH parapump are developed for varied objectives of separation. A Two-pH Levels Parapump is capable of enriching the product stream with solute components; a Three-pH Levels Parapump is capable of splitting components into two product streams. The separation capability of multi-column parapump is greatly superior to that of single-column parapump. As compared to cycling …

Correlation Of Thixotropic Parameters And Related Tests Of Blood From Human Subjects, Walter Fabisiak

Dissertations

The flow behavior of human blood is an important facet of the circulatory system as it affects all of the organs of the body. The rheological properties of whole blood provide a means of analyzing the flow of red cells and plasma through the microcirculation. A recently observed rheological characteristic of whole human blood is thixotropy, a time-dependent phenomenon. This phenomenon is caused mainly by the redistribution of an aggregated form of erythrocytes, known as rouleaux, and the non-aggregated, single erythrocytes. In order to further define and analyze the thixotropic properties of blood, the Huang model is used to quantitatively …

Thixotropic Properties Of Whole Human Blood, Jen An Su

Dissertations

The rheological property of whole blood from various human subjects was studied with a Weissenberg Rheogonio-meter, modified with a continuously variable speed drive. Experimental data showed a hysteresis loop in the shear stress versus the shear rate plot and a torque-decay in the shear stress versus the shearing time plot which is under a constant shear rate. The rheological equation previously developed by Huang was employed to define the thixotropic parameters of each whole blood sample based upon the recorded rheograms.

The altered thixotropic parameters for the blood from patients with open heart surgery at different clinical stages were quantitatively …

The Continuous Non-Equilibrium Parametric Pump: A Theoretical And Experimental Study, John Lawrence Rak

Dissertations

A continuous parametric pump in which the feed and product streams flow steadily both in upflow and downflow (hot and cold temperatures, respectively) is examined theoretically and experimentally. The model system is Sodium Chloride-Water-Bio Rad AG11A8 Ion Retardation Resin, a physical system characterized by relatively slow interphase mass transfer rates. For short half-cycle times, where interphase equilibrium is not approached, separation of the salt from water is found to be enhanced by longer half-cycle times, smaller reservoir displacements, and longer adsorbant columns. In most cases, separation improves with increasing number of cycles. However, steadily degrading separation is found to exist …

Flow Of Polymer Melt Blends Through Porous Media, James Atwood Parker

Dissertations

The flow of molten polystyrene, poly(methyl methacrylate) and three blends of these polymers has been studied in a rheogoniometer and in packed beds of unconsolidated spherical glass beads. One primary purpose of the study was to determine the behavior of polymer melt blends in porous media flow. The second major purpose of the work was to develop and test a new and powerful model for packed bed flow based upon the Huang generalized rheological constitutive equations.

Rheological characterization of the pure polymers and blends was obtained using a Roberts-Weissenberg rheogoniometer. Shear and normal stresses were measured at shear rates from …

Sodium-Initiated Polymerization Of Alpha-Methylstyrene In The Vicinity Of Its Reported Ceiling Temperature, Shuenn-Long Ou

Dissertations

No abstract provided.

Distributed Parameter Sensitivity Theory To Solve Certain Reliability Problems, Moses Nee Buernor Ayiku

Dissertations

It is well known that in actual control systems there are uncontrolled parameter changes caused by aging of elements, temperature, pressure and effects of externalmedium, among others, which may impair the performance ofthe system. Hence, there is the need to develop systems that weakly react to these parameter fluctuations. Sensitivity theory has been developed to study some of these problems. Most of the investigations in this area, however, deal with problems in continuous systems modeled by ordinary differential equations. Even the recent publications on sensitivity problems in distributed parameter control systems are largely concerned with systems modeled by first order …

Preparation And Magnetic Properties Of Rare Earth Garnets And Apatites, Rostam Mondegarian

Dissertations

It has been found possible to prepare garnets with magnetic trivalent rare earth ions filling all or most dodecahedral sites while nonmagnetic Sc³⁺ ions fill all octahedral sites and magnetic Fe³⁺ ions fill all or most tetrahedral sites. Phase-pure garnets found include {RE_3-ySc_y}[Sc₂](Fe₃)O₁₂, where RE is Sm, Eu, Gd, Tb or Dy and y can be zero with Sm and Eu; {Nd₃}[Sc₂](Fe_zGa_3-z)O₁₂; and other Nd-Sc-Fe garnets of the type {Nd_3-(w+y)M_wS_cy}[Sc₂](Fe …

Separations Of Multicomponent Mixtures Via Thermal Parametric Pumping, John Daniel Stokes

Dissertations

This dissertation covers the separation of solutes from multicomponent solutions via direct mode thermal parametric pumping.

Dilute solution separations were predicted from existing binary equations by assuming the existence of pseudo binary systems, each system consisting of one solute and the common solvent. Two systems, toluene-aniline-n-heptane and toluene-acetophenone-n-heptane with a silica gel adsorbent were used to experimentally demonstrate the separation. Experimental results were in good agreement with the mathematical predictions.

For concentrated multicomponent solutions, the separation was demonstrated by the system, toluene-acetophenone-n-heptane on silica gel. The effects of mass transfer and nonlinear adsorption isotherms became significant and a numerical solution …

Characterization Of Thixotropic Materials And Modification Of The Weissenberg Rheogoniometer, Paul Joseph Orosz

Dissertations

A Weissenberg Rheogoniometer, Model R-18, was modified to give complete rheological curves without resetting the gearbox and generate hysteresis loops for time-dependent, non-Newtonian materials. This modified instrument was used to analyze a number of materials. Standard Newtonian and known time-independent, non-Newtonian materials were studied to insure the accuracy of the instrument. Results indicated that the instrument would reproduce known viscosities of these materials, give consistent results, and not display inherent hysteresis loops with non-thixotropic materials. Materials known and suspected to be thixotropic: silicone grease-oil mixture, montmorillonite clay, and blood were tested. All displayed the characteristic hysteresis loop usually associated with …