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School of Chemical and Biomolecular Engineering Seminar Series

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    Conversion of Bio-Based Molecules: New Catalytic Approaches
    (Georgia Institute of Technology, 2012-11-07) Shanks, Brent
    The development of catalytic processes for generating bio-based chemicals will require the emergence of new catalytic systems. Given the excess oxygen present, acid catalyzed dehydration is an important reaction in producing bio-based chemicals. The limited volatility of many biobased reactants necessitates that catalytic systems need to be developed that can operate in the aqueous phase. Glucose conversion to 5-hydoxymethylfurfural (HMF) using a combination of Brønsted and Lewis acid catalysts will be discussed in which a key issue is the balance between Brønsted and Lewis acidity. Water compatible Lewis acid catalysts such as lanthanide chlorides were utilized to give respectable yields of HMF while being operated with less Brønsted acid. Ideally, heterogeneous catalysts could be synthesized for these reactions, however, the materials would need to be hydrothermally stable. Sulfonated carbons, which have been proposed as hydrothermally stable solid Brønsted acid catalysts, were examined under relevant reaction conditions. The stability behavior and structural characterization via solid state carbon NMR of sulfonated carbons synthesized using several strategies from carbohydrates will be compared. Finally, the strategy being developed by CBiRC for creating a general framework for catalytic systems designed to produce bio-based chemicals, which employs combined biocatalytic and chemical catalytic systems, will be discussed.
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    Sophisticated Point-of-Care Diagnostic Devices Based on 2D Paper Networks
    (Georgia Institute of Technology, 2012-10-24) Yager, Paul
    The long-range goal of the Yager laboratory is to decentralize medical testing for improved health, improved quality of life, and reduction in the cost of healthcare in the developed and developing worlds. Our approach has been to apply microfluidics to biosensors for point-of-care medical diagnostics. To reduce the cost and complexity of the tests our work in the last three years has focused on expanding the capabilities of paper-based diagnostics. Wicking is a robust method for moving fluids that can be the basis of much more sophisticated chemical processing than has been employed in today’s lateral flow tests. Two-dimensional paper networks (2DPNs) can perform complex chemical processes, but we keep the paper structures as simple as possible to minimize manufacturing costs. We are involved in two primary ongoing “demonstration projects”; both will develop 2DPN-based diagnostics, and both are small sample-to-result disposable devices that will convert pathogen counts on a nasal swab to intensity of colored spots. Key features are that they will require almost no activity on the part of the end-user after inserting the swab, and they will dispense with support equipment except a camera-equipped smart phone if quantitative detection instruments is needed. One device will perform chemical signal amplification to provide a more sensitive and multiplexed immunoassay for influenza. Collaborators are designing protein-binding molecules superior to antibodies for incorporation into the 2DPN. The other project incorporates isothermal nucleic acid amplification into the fully-disposable format, allowing detection of a few copies of specific nucleic acid sequences; our initial analytes are DNA from methicillin-resistant Staph. aureus (MRSA) or RNA from influenza. The devices will incorporate all functions, including swab elution, analyte isolation, amplification, and visible detection, and provide disposable heaters to support the amplification.
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    Disassembling and Reconstructing Ionic Liquids: Finding New Molecular Building Blocks for CO2 Capture Applications
    (Georgia Institute of Technology, 2012-09-05) Bara, Jason E.
    Research using ionic liquids (ILs) in gas separations is now entering its second decade. The versatility and tunability of ILs has resulted in a great number of unique materials (bulk solvents, reactive/reversible ILs, polymer membranes, gels, etc.) being produced for study in CO2 capture applications. Yet, given the advancements over the past several years in the state of IL materials development, there is a need to re-visit some fundamental aspects of ILs in order to broaden the opportunities for IL-based technologies in CO2 capture processes. We have turned our attention to understanding the fundamental properties of imidazoles – found at the cores of many ILs – as a means of better understanding and improving IL performances. By employing less common (but readily available) imidazole substrates as starting materials, new dimensions of control over thermophysical properties and chemical reactivity can be achieved. Via a synergistic experimental and computational approach, material properties can be rapidly screened and modeled, with feedback used to suggest new targets. Furthermore, during this process of disassembly and reconstruction, we have found new opportunities where imidazoles themselves may hold advantages as materials for CO2 capture applications.
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    Putting Chemistry to Work for Nano and Biomedical Research
    (Georgia Institute of Technology, 2012-08-29) Xia, Younan
    Nanomaterials are finding widespread use in many applications, including electronics, photonics, information storage, catalysis, as well as diagnosis and treatment of diseases. Chemistry plays a pivotal role in all these exciting developments because it allows for the synthesis of nanomaterials with well-controlled sizes, shapes, compositions, structures, and properties. In this talk, I will demonstrate this concept using a number of examples from my own research group, including silver/palladium nanocubes, gold nanocages, and platinum nanodendrites. While the synthetic methods mainly involve solution-phase redox chemistry, we have been working diligently to understand the complex physics behind the simple chemistry – that is, the nucleation and growth mechanisms leading to the formation of nanocrystals with specific shapes. For example, we have discovered that the shape of metal nanocrystals are dictated by the crystallinity and structure of the seeds, which are, in turn, controlled by factors such as reduction kinetics, oxidative etching, diffusion, and surface capping. The methodologies we have developed seem to work well for all noble metals including silver, gold, palladium, platinum, and rhodium. The success of these syntheses has enabled us to tailor the electronic, plasmonic, and catalytic properties of noble-metal nanocrystals for a range of applications in catalysis and biomedical research.
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    BP Oil Tragedy: What Went Wrong and Leadership Challenges
    (Georgia Institute of Technology, 2012-04-18) Stancell, Arnold F.
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    Collapsing Colloidal Gels: How and When?
    (Georgia Institute of Technology, 2012-03-15) Russel, William B.
    Drying colloidal dispersions by evaporating the liquid to create particulate solids, porous coatings, or continuous films is common to a number of important technologies, ranging from applying latex paint and manufacturing photographic film to depositing highly porous coatings on ink jet papers and fabricating photonic crystals from silica sols. The objective is generally to create a layer of specified thickness and controlled porosity with permeability, strength, transparency, or other physical properties. Both the understanding and implementation of drying processes have advanced considerably in the past two decades. Yet processing still raises a number of interesting and difficult issues because of conflicting constraints and performance properties. The focus of this talk is the complex phenomena that emerge as evaporation drives fluid flow in the thin film. Rapid evaporation can segregate binary mixtures or create an impermeable skin at the surface. Slower evaporation produces a porous packing subject to a rising capillary pressure that deforms the particles. Elastic deformation can cause cracking and peeling, while a viscous response can produce a pore-free solid.
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    High Level Nuclear Waste at the Savannah River Site— Past, Present, and Future
    (Georgia Institute of Technology, 2012-03-07) Hobbs, David T.
    The Savannah River Site (SRS) operated five heavy water nuclear reactors and two separation canyons for the production of nuclear materials for defense, special isotope production and space programs. These operations produced more than 100 million gallons of high-level nuclear waste (HLW), which has been stored in underground carbon steel tanks. The highly alkaline HLW consists of three forms; precipitated metal hydroxides and hydrous metal oxides referred to as sludge, supernatant liquids or supernate, and crystalline sodium salts referred to as saltcake that are formed upon evaporation and cooling of waste supernates. The current inventory of HLW at SRS is about 38 million gallons. Disposition of the HLW seeks to immobilize more than 99% of the radioactivity in a highly durable borosilicate glass wasteform. Concentrated liquid and saltcake are retrieved and pretreated to remove cesium, strontium, and alpha-emitting radionuclides. The separated radioactive components transfer into the Defense Waste Processing Facility (DWPF) for vitrification along with the sludge fraction of the HLW. The decontaminated liquid waste transfers into the Saltstone Production Facility (SPF) for incorporation into a cement wasteform for onsite disposal as a low-level waste. The DWPF began radioactive service in 1996 and to date has produced more than 3250 glass canisters. The SPF began radioactive operations in 1990 and has immobilized more than XX million gallons of decontaminated waste liquids. Two pilot-scale pretreatment facilities, the Actinide Removal Process (ARP) and the Modular Caustic Side Solvent Extraction Unit (MCU) began radioactive operations at SRS in 2008. The ARP facility uses an inorganic ion exchanger, monosodium titanate (MST), to remove 90Sr and alpha-emitting radionuclides (principally 238Pu, 239Pu, 240Pu and 237Np). Following treatment with MST, the waste passes into the MCU for removal of radio-cesium using a calixarene extractant. The Salt Waste Processing Facility (SWPF), currently under construction will use these same processes to treat the HLW at a throughput of about 7 million gallons per year beginning in 2014. A new initiative, referred to as the Small Column Ion Exchange (SCIX) process is under development to accelerate pretreatment of salt wastes at SRS. The SCIX operation uses an inorganic ion-exchanger, crystalline silicotitanate (CST) for the separation of cesium and strontium from waste solutions. This separation technology will feature two small ion-exchange columns located within a high-level waste tank.
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    Combining Science and Engineering for Molecular Separations: Thoughts from a Career
    (Georgia Institute of Technology, 2012-02-15) Belfort, Georges
    In this lecture, I will attempt to integrate several aspects of my research with selected recent grand challenges announced by the U.S. National Academy of Engineering¹. In addition, I hope to demonstrate that collaboration with physicists, chemists, surface scientists and biologists allow us to address difficult engineering problems with new cross-disciplinary approaches. A seminal overall goal is to improve energy efficiency through process improvements. This includes using secondary flows² (with physicists at the General Electric Global Research Laboratories using magnetic resonance imaging), protein-resistant surface chemistries³ (with surface scientists and engineers at MIT using high throughput combinatorial synthesis) and recombinant DNA technology⁴ (with a biologist at The State University of New York at Albany, using protein with unusual self-splicing properties called inteins) to substantially increase bio-separation performance. In addition, inspired by Nature, we investigate the mechanism of transport through the nuclear pore complex from the cytoplasm to the nucleus, and then successfully mimic its separating behavior⁵ (with Scientists from Rockefeller University). Collaborating with engineers is fast becoming an important aspect of fundamental discovery in biology. Examples include DNA sequencing machines and analysis of large amounts of data using bioinformatics. This presentation offers an inverse process of a chemical engineer who collaborates with a range of scientists. References 1. http://www.grandchallengescholars.org/ 2. Mallubhotla, H, Edelstein, W. A., Earley, T. A. and Belfort, G., (2001) Magnetic resonance flow imaging and numerical analysis of curved tube flow: 16. Effect of curvature and flow rate on Dean vortex stability and bifurcation, AIChE J., 47 (5) 1126-1140. 3. Zhou, M., Liu, H., Venkiteshwaran, A., Kilduff, J. C., Anderson, D. G., Langer, R. and Belfort G. (2011) High throughput discovery of new fouling-resistant surfaces, J. Mater. Chem., 21, 693-704. 4. Wood, D., Derbyshire V. Wu, W., Chartrain, M, Belfort, M., and Belfort G. (2000) Optimized Single-Step Affinity Purification with a Self-Cleaving Intein Applied to a Human Fibroblast Growth Factor, Biotechnology Progress 16, 1055-1063. 5. Nurse, P., (2008) Life, logic and information, Nature 454 (24) 424-426.
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    Diffusion in Nanostructured Systems by High-Field NMR
    (Georgia Institute of Technology, 2011-12-07) Vasenkov, Sergey
    Fundamental knowledge of an influence of structural inhomogeneity on transport properties of nanostructured systems in a broad range of length scales between hundreds of nanometers and tens of microns can be obtained by using a pulsed field gradient (PFG) NMR technique that combines advantages of high field (17.6 T) NMR and high magnetic field gradients (up to 30 T/m). This technique has been recently introduced at the University of Florida in collaboration with the National Magnet Lab. Several examples of diffusion studies using this technique will be discussed in detail. These examples include uncovering transport-structure relationship in room temperature ionic liquids and their mixtures with water and carbon dioxide as well as in multicomponent lipid bilayers containing membrane domains. In addition to a more conventional 1H PFG NMR, also 13C PFG NMR was used.
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    Molecular Simulations of Molecules and Membranes: Contributions to Mechanistic Understanding in Biology (RNA Delivery) and in Gas Separation (Quantum Isotopic Sieving)
    (Georgia Institute of Technology, 2011-11-16) Smith, Sean
    In this talk I will provide an overview of ways in which computational molecular science is able to contribute to mechanistic understanding as well as raising new questions and suggesting new approaches in diverse areas of technology. The two specific application areas considered are short-strand RNA delivery for gene therapy and quantum mediated kinetic sieving of molecular isotopes of hydrogen.