Chemical Engineering Commons^™

Bringing The Analysis Of Electrodeposition Signals In Voltammetry Out Of The Shadows, Devin Rappleye, Ranon G. Fuller

Faculty Publications

Voltammetry studies of electrodeposition are growing rapidly. Yet, relations for the analysis of electrodeposition reactions in voltammetry remain relatively obscure in the literature. The existing cyclic and square wave voltammetry relations for electrodeposition and their limitations are discussed to increase awareness. A retrospective analysis is performed to demonstrate the impact of model selection in improving the analysis of electrodeposition behavior with voltammetric data. A repository for voltammetry models of electrodeposition is proposed to further increase familiarity and application of the most appropriate models, which would support a rapidly growing area of research and technological development.

Nonsolvent-Induced Phase Separation Inside Liquid Droplets, Rami Alhasan, Tanner A. Wilcoxson, Dakota S. Banks, Sion Jung, Douglas R. Tree

Faculty Publications

Nonsolvent-induced phase separation (NIPS) is a popular method for creating polymeric particles with internal microstructure, but many fundamental questions remain surrounding the kinetics of the complex coupled mass transfer and phase separation processes. In this work, we use simulations of a phase-field model to examine how (i) finite domain boundaries of a polymer droplet and (ii) solvent/nonsolvent miscibility affect the NIPS process. To isolate the effects of phase separation kinetics and solvent/nonsolvent mass transfer on the NIPS process, we study two different cases. First, we investigate droplet concentrations that originate inside the two-phase region, where phase separation kinetics alone governs …

Hierarchical, Porous Hydrogels Demonstrating Structurally Dependent Mechanical Properties, Elisabeth Lloyd, Rami Alhasan, Sujata Dhakal, Svetlana Morozova, Douglas R. Tree, Robert Hickey

Faculty Publications

While hierarchical ordering is a distinctive feature of natural tissues and is directly responsible for their diverse and unique properties, research efforts to synthesize biomaterials have primarily focused on using molecular-based approaches without considering multiscale structure. Here, we report a bottom-up self-assembly process to produce highly porous hydrogels that resemble natural tissues both structurally and mechanically. Randomly oriented, physically crosslinked nanostructured micelles form the walls of aligned, polymer-rich pore walls that surround water-rich cavities. Extremely soft elastic modulus (<  1 kPa), highly stretchability (greater than 12-times), strain-hardening, and completely reversible deformation result from the hierarchical structure. Independent control of nano and macroscales is realized through the combination of polymer macromolecular parameters and processing conditions, directly impacting the resulting phase behavior. Here, we demonstrate precise control of the material structure and structure orientation over many orders of magnitude (e.g., nm – µm), and reveal how the multiscale structure directly impacts mechanical properties.

Design And Performance Of A Laboratory Scale Pressurized Oxy-Coal Reactor, Scott Gardner, Cody Carpenter, Jacob Tuia, Aaron Skousen, Dustin Badger, Sandra Thomas, Bradley R. Adams, Dale R. Tree, Andrew R. Fry

Faculty Publications

A pressurized oxy-coal (POC) reactor has been designed, built and tested to investigate key technologies related to oxy-coal combustion including a dry coal feed system, an oxy-coal burner, and a slagging ash management system. The coal feed system utilized a fluidized bed to convey pulverized coal with CO2 from a coal bed into the reactor. The reactor has diagnostic capabilities including optical access, embedded thermocouples, fuel and gas flow rates, exhaust gas analysis (CO2, CO, NO, O2) and heat flux. At 13.6 atm and a firing rate of 89 kWth a mean feed rate of 12.5 kg/h was …

Semi-Differentiation Of Reversible, Soluble-Insoluble Potential Sweep Voltammograms, Tyler Williams, Ranon Fuller, Cameron Vann, Devin Rappleye

Faculty Publications

Semi-differentiation, or convolution as it is sometimes known, is a mathematical technique commonly used to disentangle overlapping peaks in cyclic or linear sweep voltammograms. However, this technique is often misapplied due to misunderstandings of fractional calculus. Additionally, rigorous treatment and validation of the theory of semi-differential analysis of reversible, soluble-insoluble electrochemical reactions is lacking. Peculiarities of semi-differentiation are explored; theoretical relations for semi-differentiated voltammograms are given; the exponential nature of the theoretical curve is explored; theoretical relations are compared to experimental voltammograms for AgNO₃ in 1 M nitric acid at 298 K, NiCl₂ in LiCl at 974 K, …

Simulations Of Morphology Control Of Self-Assembled Amphiphilic Surfactants, Qinyu Zhu, Douglas R. Tree

Faculty Publications

One of the grand challenges of amphiphilic self-assembly is the design of ordered structures whose morphology or shape can be explicitly and dynamically controlled by adjusting the properties of the amphiphiles or their surroundings. Such a capacity would enable researchers to create synthetic systems with functionality that meets or exceeds biological cells, and provide a robust platform for a broad range of engineering applications such as artificial tissues, drug delivery, and separation membranes. Despite significant progress, important fundamental questions remain unanswered, due in part to the limited resolution and the restricted parameter spaces that are readily accessible in experiments. Computational …

Control Education For Societal-Scale Challenges: A Community Roadmap, John Anthony Rossiter, Christos G. Cassandras, João Hespanha, Sebastian Dormido, Luis De La Torre, Gireeja Ranade, Antonio Visioli, John Hedengren, Richard M. Murray, Panos Antsaklis, Francoise Lamnabhi-Lagarrigue, Thomas Parisini

Faculty Publications

This article focuses on extending, disseminating and interpreting the findings of an IEEE Control Systems Society working group looking at the role of control theory and engineering in solving some of the many current and future societal challenges. The findings are interpreted in a manner designed to give focus and direction to both future education and research work in the general control theory and engineering arena, interpreted in the broadest sense. The paper is intended to promote discussion in the community and also provide a useful starting point for colleagues wishing to re-imagine the design and delivery of control-related topics …

Simulations Of Morphology Control Of Self-Assembled Amphiphilic Surfactants, Qinyu Zhu, Douglas R. Tree

Faculty Publications

One of the grand challenges of amphiphilic self-assembly is the design of ordered structures whose morphology or shape can be explicitly and dynamically controlled by adjusting the properties of the amphiphiles or their surroundings. Such a capacity would enable researchers to create synthetic systems with functionality that meets or exceeds biological cells, and provide a robust platform for a broad range of engineering applications such as artificial tissues, drug delivery, and separation membranes. Despite significant progress, important fundamental questions remain unanswered, due in part to the limited resolution and the restricted parameter spaces that are readily accessible in experiments. Computational …

Sootlib: A Soot Model Library For Combustion Simulation, Victoria B. Stephens, Joshua Bedwell, Alex J. Josephson, Keturah Oldham, David O. Lignell

Faculty Publications

Soot formation in combustion is an important process that affects radiative heat transfer, flame temperatures, and emissions with health and environmental impacts. Soot formation involves complex chemistry for nucleation, growth, oxidation, and coagulation processes. The soot particles vary widely in size and accurate modeling requires representation of the particle size distribution (PSD). Modeling soot is not trivial, and is only one of several physical processes active in combustion systems. This paper presents a software package called SootLib, which is an open-source library for modeling soot formation and other aerosol systems. SootLib is written in C++, is documented with Doxygen, and …

Turbulent Mixing Simulation Using The Hierarchical Parcel-Swapping (Hips) Model, Tommy Starick, Masoomeh Behrang, David O. Lignell, Heiko Schmidt, Alan R. Kerstein

Faculty Publications

Turbulent mixing is an omnipresent phenomenon that permanently affects our everyday life. Mixing processes also
plays an important role in many industrial applications. The full resolution of all relevant flow scales often poses a major challenge to the numerical simulation and requires a modeling of the small-scale effects. In transported Probability Density Function (PDF) methods, the simplified modeling of the molecular mixing is a known weak point. At this place, the Hierarchical Parcel-Swapping (HiPS) model developed by A.R. Kerstein [J. Stat. Phys. 153, 142-161 (2013)] represents a computationally efficient and novel turbulent mixing model. HiPS simulates the effects of turbulence …

Active Control Of Equilibrium, Near-Equilibrium, And Far-From-Equilibrium Colloidal Systems, Mark N. Mcdonald, Qinyu Zhu, Walter F. Paxton, Cameron K. Peterson, Douglas R. Tree

Faculty Publications

The development of top-down active control over bottom-up colloidal assembly processes has the potential to produce materials, surfaces, and objects with applications in a wide range of fields spanning from computing to materials science to biomedical engineering. In this review, we summarize recent progress in the field using a taxonomy based on how active control is used to guide assembly. We find there are three distinct scenarios: (1) navigating kinetic pathways to reach a desirable equilibrium state, (2) the creation of a desirable metastable, kinetically trapped, or kinetically arrested state, and (3) the creation of a desirable far-from-equilibrium state through …

Ash Aerosol Particle Size Distribution, Composition, And Deposition Behavior While Co-Firing Coal And Steam-Exploded Biomass In A 1.5 Mwth Combustor, Rajarshi Roy, Brian Schooff, Xiaolong Li, Scott Montgomery, Jacob Tuttle, Jost O.L. Wendt, Kingsley Dickson, Brian Iverson, Andrew R. Fry

Faculty Publications

Five different blends of Utah bituminous coal and steam-exploded pine (100/0, 75/25, 50/50, 25/75, 0/100 by mass) were fired in a 1.5 MWth combustor. Primary objectives were to understand mineral matter behavior by analyzing aerosol size distribution, aerosol size-segregated composition, ash deposition mass, and ash composition. For particle size < 0.1 μm, pure coal had the lowest aerosol concentration and pure biomass showed the highest (higher nucleation of potassium salts), a trend which reversed for particles >0.1 μm. During pure biomass combustion, aerosol particles >15 μm contained higher mass fractions of potassium (+126%), calcium (+132%), and iron (+115%) and lower fractions of aluminum (−49%) and silicon (−29%) than pure coal. Ash deposition mass decreased with increasing biomass blends. …

Steering Particles Via Micro-Actuation Of Chemical Gradients Using Model Predictive Control, Mark N. Mcdonald, Cameron K. Peterson, Douglas R. Tree

Faculty Publications

Biological systems rely on chemical gradients to direct motion through both chemotaxis and signaling, but synthetic approaches for doing the same are still relatively naïve. Consequently, we present a novel method for using chemical gradients to manipulate the position and velocity of colloidal particles in a microfluidic device. Specifically, we show that a set of spatially localized chemical reactions that are sufficiently controllable can be used to steer colloidal particles via diffusiophoresis along an arbitrary trajectory. To accomplish this, we develop a control method for steering colloidal particles with chemical gradients using nonlinear model predictive control with a model based …

Figure Data From "Electrochemical Identification Of Metal Chlorides In Eutectic Licl-Kcl Without Prior Knowledge Of Analyte Identities", Tyler Williams, Jason Torrie, Mark Schvaneveldt, Ranon Fuller, Greg Chipman, Devin Rappleye

ScholarsArchive Data

This is the data associated with figures found in a publication by the authors with the name of "Electrochemical Identification of Metal Chlorides in Eutectic LiCl-KCl Without Prior Knowledge of Analyte Identities".

Some of the data saved here is raw data collected by an Autolab potentiostat, while other data was derived from this raw data. Please reach out to the corresponding author for further questions.

Deep Transfer Learning For Approximate Model Predictive Control, Samuel Arce Munoz, Junho Park, Cristina M. Stewart, Adam M. Martin, John Hedengren

Faculty Publications

Transfer learning is a machine learning technique that takes a pre-trained model that has already been trained on a related task, and adapts it for use on a new, related task. This is particularly useful in the context of model predictive control (MPC), where deep transfer learning is used to improve the training of the MPC by leveraging the knowledge gained from related controllers. One way in which transfer learning is applied in the context of MPC is by using a pre-trained deep learning model of the MPC, and then fine-tuning the controller training for a new process automation task. …

Engineering At-Home Dilution And Filtration Methods To Enable Paper-Based Colorimetric Biosensing In Human Blood With Cell-Free Protein Synthesis, Tyler J. Free, Ryan W. Tucker, Katelyn M. Simonson, Sydney A. Smith, Caleb M. Lindgren, William G. Pitt, Bradley C. Bundy

Faculty Publications

Diagnostic blood tests can guide the administration of healthcare to save and improve lives. Most clinical biosensing blood tests require a trained technician and specialized equipment to process samples and interpret results, which greatly limits test accessibility. Colorimetric paper-based diagnostics have an equipment-free readout, but raw blood obscures a colorimetric response which has motivated diverse efforts to develop blood sample processing techniques. This work uses inexpensive readily-available materials to engineer user-friendly dilution and filtration methods for blood sample collection and processing to enable a proof-of-concept colorimetric biosensor that is responsive to glutamine in 50 µL blood drop samples in less …

Surface Modification Of 3d Printed Microfluidic Devices For Controlled Wetting In Two-Phase Flow, Chandler A. Warr, Nicole G. Crawford, Gregory P. Nordin, William G. Pitt

Faculty Publications

Microfluidic devices (MFDs) printed in 3-D geometry using digital light projection to polymerize monomers often have surfaces that are not as hydrophobic as MFDs made from polydimethylsiloxane. Droplet microfluidics in these types of devices are subject to droplet adhesion and aqueous spreading on less hydrophobic MFD surfaces. We have developed a post-processing technique using hydrophobic monomers that renders the surfaces of these devices much more hydrophobic. The technique is fast and easy, and involves flowing monomer without initiator into the channels and then exposing the entire device to UV light that generates radicals from the initiator molecules remaining in the …

Machine Learning With Gradient-Based Optimization Of Nuclear Waste Vitrification With Uncertainties And Constraints, Lagrande Gunnell, Kyle Manwaring, Xiaonan Lu, Jacob Reynolds, John Vienna, John Hedengren

Faculty Publications

Gekko is an optimization suite in Python that solves optimization problems involving mixed-integer, nonlinear, and differential equations. The purpose of this study is to integrate common Machine Learning (ML) algorithms such as Gaussian Process Regression (GPR), support vector regression (SVR), and artificial neural network (ANN) models into Gekko to solve data based optimization problems. Uncertainty quantification (UQ) is used alongside ML for better decision making. These methods include ensemble methods, model-specific methods, conformal predictions, and the delta method. An optimization problem involving nuclear waste vitrification is presented to demonstrate the benefit of ML in this field. ML models are compared …

Techno-Economic Sensitivity Analysis For Combined Design And Operation Of A Small Modular Reactor Hybrid Energy System, Daniel Hill, Adam Martin, Nathanael Martin-Nelson, Charles Granger, Kody Powell, John Hedengren

Faculty Publications

With increasing grid-penetration of renewable energy resources and a rising need for carbon-free dispatchable power generation, nuclear-hybrid energy systems (NHES), consisting of small modular reactors, are an increasingly attractive option for maintaining grid stability. NHES can accomplish this with a minimal carbon footprint but there are significant uncertainties that are not fully understood. This work describes and demonstrates methods for analyzing the uncertainties of potential NHES designs, including uncertain design parameters and time series as well as variations in dispatch horizon length. The proposed methods are demonstrated on a sample system with 16 design parameters, 3 uncertain time series, and …

Li-Ion Electrode Microstructure Evolution During Drying And Calendering, Mojdeh Nikpour, Baichuan Liu, Paul Minson, Zachary Hillman, Brian A. Mazzeo, Dean R. Wheeler

Faculty Publications

The drying process of electrodes might seem to be a simple operation, but it has profound effects on the microstructure. Some unexpected changes can happen depending on the drying conditions. In prior work, we developed the multiphase-smoothed-particle (MPSP) model, which predicted a relative increase in the carbon additive and binder adjacent to the current collector during drying. This motivated us to undertake the present experimental investigation of the relationship between the drying rate and microstructure and transport properties for a typical anode and cathode. Specifically, the drying rate was controlled by means of temperature for both an NMC532 cathode and …

An Acoustofluidic Scanning Nanoscope Using Enhanced Image Stacking And Processing, Geonsoo Jin, Joseph Rich, Jianping Xia, Albert J. He, Chenglong Zhao, Tony Jun Huang

Faculty Publications

Nanoscale optical resolution with a large field of view is a critical feature for many research and industry areas, such as semiconductor fabrication, biomedical imaging, and nanoscale material identification. Several scanning microscopes have been developed to resolve the inverse relationship between the resolution and field of view; however, those scanning microscopes still rely upon fluorescence labeling and complex optical systems. To overcome these limitations, we developed a dual-camera acoustofluidic nanoscope with a seamless image merging algorithm (alpha-blending process). This design allows us to precisely image both the sample and the microspheres simultaneously and accurately track the particle path and location. …

No Formation During Co-Combustion Of Coal With Two Thermally Treated Biomasses, Thomas Allgurén, Klas Andersson, Andrew R. Fry, Eric G. Eddings

Faculty Publications

The combustion behavior of biomass as a fuel varies dependent on source of the raw material, but also on the type of pre-treatment. In this work steam exploded and torrefied woody biomass were studied with respect to NOx formation in co-firing experiments. Most of the reported data is based on small scale experiments and simulations. In this work, however, have three different cases been investigated experimentally in a 1.5MWth combustor supported by reaction simulations. One case corresponds to firing 100% Utah bituminous coal and two cases where 15% of the coal (on a mass basis) has been replaced with either …

Computational Methods To Simulate Molten Salt Thermophysical Properties, Talmage Porter, Michael M. Vaka, Parker Steenblik, Dennis Della Corte

Faculty Publications

Molten salts are important thermal conductors used in molten salt reactors and solar applications. To use molten salts safely, accurate knowledge of their thermophysical properties is necessary. However, it is experimentally challenging to measure these properties and a comprehensive evaluation of the full chemical space is unfeasible. Computational methods provide an alternative route to access these properties. Here, we summarize the developments in methods over the last 70 years and cluster them into three relevant eras. We review the main advances and limitations of each era and conclude with an optimistic perspective for the next decade, which will likely be …

Electroanalytical Measurements Of Lanthanum (Iii) Chloride In Molten Calcium Chloride And Molten Calcium Chloride And Lithium Chloride, Mark H. Schvaneveldt, Ranon Fuller, Devin Rappleye

Faculty Publications

Cyclic voltammetry (CV), square wave voltammetry (SWV) and other electroanalytical methods have been applied to molten chloride salts to study metal ion behavior. These studies have been useful for understanding and optimizing the electrowinning of metals. Notable ions that have been studied are rare earth and actinide metal ions in LiCl-KCl salts. However, the behavior of lanthanum (La³⁺) ions in some molten chlorides or chloride mixtures (e.g., CaCl₂) has not been studied. CV experiments were conducted to evaluate La³⁺ behavior in CaCl₂-LiCl and CaCl₂ and were compared to La³⁺ behavior in …

Acoustofluidics For Simultaneous Nanoparticle-Based Drug Loading And Exosome Encapsulation, Zeyu Wang, Joseph Rich, Nanjing Hao, Yuyang Gu, Chuyi Chen, Shujie Yang, Peiran Zhang, Tony Jun Huang

Faculty Publications

Nanocarrier and exosome encapsulation has been found to significantly increase the efficacy of targeted drug delivery while also minimizing unwanted side effects. However, the development of exosome-encapsulated drug nanocarriers is limited by low drug loading efficiencies and/or complex, time-consuming drug loading processes. Herein, we have developed an acoustofluidic device that simultaneously performs both drug loading and exosome encapsulation. By synergistically leveraging the acoustic radiation force, acoustic microstreaming, and shear stresses in a rotating droplet, the concentration, and fusion of exosomes, drugs, and porous silica nanoparticles is achieved. The final product consists of drug-loaded silica nanocarriers that are encased within an …

Photo-Induced Drug Release From Polymeric Micelles And Liposomes: Phototriggering Mechanisms In Drug Delivery Systems, Najla M. Salkho, Nahid S. Awad, William G. Pitt, Ghaleb A. Husseini

Faculty Publications

Chemotherapeutic drugs are highly effective in treating cancer. However, the side effects associated with this treatment lower the quality of life of cancer patients. Smart nanocarriers are able to encapsulate these drugs to deliver them to tumors while reducing their contact with the healthy cells and the subsequent side effects. Upon reaching their target, the release of the encapsulated drugs should be carefully controlled to achieve therapeutic levels at the required time. Light is one of the promising triggering mechanisms used as external stimuli to trigger drug release from the light-responsive nanocarriers. Photo-induced drug release can be achieved at a …

A Comparison Of Square-Wave Voltammetry Models To Determine The Number Of Electrons Exchanged In Metal Deposition, Ranon Fuller, Tyler Williams, Mark H. Schvaneveldt, Devin Rappleye

Faculty Publications

A comparison of square-wave voltammetry models for calculating the number of electrons exchanged in a metal deposition reaction. Experiments were conducted for silver deposition on platinum in an aqueous HNO₃ solution and for nickel and lanthanum deposition on platinum in molten LiCl. Diffusion coefficients for Ni²⁺ and La³⁺ in LiCl at 700^oC are calculated. Accuracy of soluble-soluble models versus a soluble-insoluble model is discussed. A simple method for determining the number of electrons exchanged under the constraint of well-compensated ohmic drop is proposed and evaluated.

The Effect Of Soot Models In Oxy-Coal Combustion Simulations, Kamron Groves Brinkerhoff

Theses and Dissertations

Soot in coal combustion simulations is often ignored due to its computational complexity, despite significant effects on flame temperature and radiation. In this research, a 40 kW oxy-coal combustion system is modeled using Large Eddy Simulations (LES) and a semi-empirical monodisperse coal soot model. Simulation results are compared to experimental measurements of temperature, species concentrations, and soot concentration. Cases where soot is modeled are compared with cases where soot is neglected to determine the accuracy benefits of modeling soot. The simulations were able to replicate experimental results within an acceptable level of error. Including soot in the simulations did not …

Ph-Responsive Nanocarriers In Cancer Therapy, Nour M. Alsawaftah, Nahid S. Awad, William G. Pitt, Ghaleb A. Husseini

Faculty Publications

A number of promising nano-sized particles (nanoparticles) have been developed to conquer the limitations of conventional chemotherapy. One of the most promising methods is stimuli-responsive nanoparticles because they enable the safe delivery of the drugs while controlling their release at the tumor sites. Different intrinsic and extrinsic stimuli can be used to trigger drug release such as temperature, redox, ultrasound, magnetic field, and pH. The intracellular pH of solid tumors is maintained below the extracellular pH. Thus, pH-sensitive nanoparticles are highly efficient in delivering drugs to tumors compared to conventional nanoparticles. This review provides a survey of the different strategies …

Thermosensitive Polymers And Thermo-Responsive Liposomal Drug Delivery Systems, Waad H. Abuwatfa, Nahid S. Awad, William G. Pitt, Ghaleb A. Husseini

Faculty Publications

Temperature excursions within a biological milieu can be effectively used to induce drug release from thermosensitive drug-encapsulating nanoparticles. Oncological hyperthermia is of particular interest, as it is proven to synergistically act to arrest tumor growth when combined with optimally-designed smart drug delivery systems (DDSs). Thermoresponsive DDSs aid in making the drugs more bioavailable, enhance the therapeutic index and pharmacokinetic trends, and provide the spatial placement and temporal delivery of the drug into localized anatomical sites. This paper reviews the fundamentals of thermosensitive polymers, with a particular focus on thermoresponsive liposomal-based drug delivery systems.