2010 Distinguished Lectures
December 2 Jason Black, GE Global Research Center
2:00 p.m., 208 DeBartolo Hall
1:00 p.m., Nieuwland Science Hall
"The Twelve Principles of Green Chemistry"
John Warner, co-founder, President, Chief Technology Officer, Chairman of the Board
Warner Babcock Institute for Green Chemistry
Dr. Warner will discuss green chemistry and how it is used to reduce or eliminate the use and/or generation of hazardous substances in the design phase of materials development.
11:00 a.m., 101 Jordan Hall of Science
Tuesday, April 20
4:00 p.m., 258 Fitzpatrick Hall
"Origins of Selectivity in Actinide Separations"
Dr. Mark Jensen, Chemical Sciences and Engineering Division
Argonne National Laboratory
As a carbon-neutral energy source, nuclear energy accounts for about 20% of the electricity produced in the United States and around the world. Chemical separations of the radioactive actinide elements and their fission products have always played critical roles in the nuclear enterprise, but concepts under consideration for new generations of nuclear reactors that run on advanced nuclear fuels and produce less radioactive waste will require separations that far surpass the performance of the chromatographic and liquid-liquid extraction processes in use today. In this context, the most pressing separations needs are for efficient and effective separations of the fission product lanthanide elements from the actinide elements americium and curium; however the great chemical similarity of these groups of elements makes this a difficult and often inefficient separation. In order to rationally design a new generation of highly effective lanthanide-actinide separations, we need a systematic molecular-level understanding of the interactions that underlie the thermodynamic selectivity of the molecules used for such separations. I will describe my work studying the structural, electronic, and thermodynamic factors underlying the modest selectivity of nitrogen and sulfur-bearing molecules for the actinide elements. These studies also provide targets for improving the efficiency of the separations by illuminating the factors responsible for the large decrease in bond strength that accompanies the moderate increase in the selectivity of molecules that favor americium and curium over the lanthanides.
Mark P. Jensen is a chemist in the Chemical Sciences and Engineering Division at Argonne National Laboratory. After joining Argonne in 1994 as a postdoctoral research associate under the direction of E. Phillip Horwitz and Kenneth L. Nash, he moved to the Heavy Elements and Separation Science Group where he has performed research since 1995. Dr. Jensen’s research interests include actinide chemistry and biochemistry in separations and the environment, mechanisms of metal selectivity in separations, metal speciation in non-aqueous solutions, chemical thermodynamics, and general radiochemistry. Dr. Jensen received several awards throughout his career, and most recently was awarded the R. G. Haire Lectureship in Actinide Science from Auburn University. He has been the Associate Editor of Solvent Extraction and Ion Exchange since 2002, and has coauthored 75 open literature papers and 2 book chapters. Dr. Jensen received his Ph.D. in Chemistry from Florida State University in 1994 and his B.S. in Chemistry from Bethel College (Minnesota) in 1989.
Friday, April 15
2:30 p.m., 258 Fitzpatrick Hall
"Pore-scale Investigation and the Applications in Energy and Environmental Sciences"
Dr. Cheng Chen, Department of Earth & Atmospheric Sciences
High-energy, synchrotron-based X-ray difference micro-tomography (XDMT) was used to resolve the pore structure of a granular porous medium, as well as colloidal deposits within the pore space, with six-micron resolution. After processed by sophisticated image processing methods, the detailed structural information was used to define internal boundaries for three-dimensional lattice Boltzmann (LB) simulations of the effects of the colloidal deposits on pore-scale fluid flow and solute transport. Colloid accumulation was observed to be highly heterogeneous at the pore scale. The change in the geometry of the pore space greatly reduced the bulk permeability of the porous medium. The pore structure evolved to become increasingly complex over time. LB simulations of solute transport indicated that the temporal variation of pore structure enhanced anomalous diffusion behavior. In addition, a coupled multiphase LB model was used to simulate the dissolution of immiscible liquid droplets in another liquid during the rising process resulting from buoyancy. When more than two identical droplets rose simultaneously in a close proximity, the average terminal rise velocity was lower than that of a single droplet with the same size, because of the mutual resistant interactions. The Damkohler (Da) and Peclet (Pe) numbers were varied to investigate the coupling between droplet size, flow field, dissolution at the interface, and solute transport. By studying the coupling between Da and Pe, we qualitatively proposed to construct a Da-Pe phase plane, and found the interface dividing the plane into region 1 and 2. Region 1 was the collection of points where it was favorable to break down the droplet into as many small ones as possible in order to accelerate dissolution, while region 2 was the collection of points where it was favorable to keep the droplet in a single one for the same purpose.
Dr. Cheng Chen was born in China. He received his B.S. degree in Hydraulic Engineering at Tsinghua University, China, and Ph.D. in Civil and Environmental Engineering at Northwestern University. He is currently a Postdoctoral Research Associate at the Department of Earth & Atmospheric Sciences, Purdue University. His research interests include geological CO2 sequestration, colloid and contaminant transport in groundwater, and stream-subsurface water interaction and transport processes.
Wednesday, April 6
3:30 p.m., 131 DeBartolo
"Modeling the Interactions of Adsorbates with Metal Surfaces and the Development of New Sorbents for Post-Combustion CO2 Capture"
Dr. John Kitchin, Chemical Engineering Department
Carnegie Mellon University
The interactions of molecules with metallic surfaces are fundamental to the ability of metals to catalyze reactions. One often thinks of a metal like platinum as the catalyst, but under reaction conditions the reactivity of the metal surfaces is modified by the molecules that adsorb on them. We have used quantum chemical calculations to probe the adsorption behavior of atomic adsorbates such as C, N, O, and S on late transition metal surfaces such as Rh, Ir, Pd, Pt, Cu, Ag, and Au(111). There are remarkable similarities in the adsorption behavior of these adsorbates that can be interpreted in terms of a simple adsorbate-induced surface electronic structure modification mechanism that is common to all the adsorbates and surfaces. The variations between the adsorbates and metals are readily explained in terms of the size of the metal and adsorbate orbitals and the geometry dependent overlap of these orbitals. We have constructed a new Solid State Table of these orbital radii from the quantum chemical calculations that can be used in conjunction with a simple model to rapidly estimate the electronic structure of metal and alloy surfaces with adsorbates on them.
The capture and sequestration of CO2 from fossil energy power generation is one technological solution to minimizing the amount of CO2 that enters the atmosphere, and may help mitigate the effects of fossil energy power generation on climate change. Sorbents are an attractive option compared to solvents for capturing CO2 from the flue gas of air-fired power plants because sorbents often have lower heat capacities than solvents, thus reducing the energy needed to regenerate the sorbent due to heating. We have examined the role of moisture in the capture mechanism of CO2 on amidine based sorbents, the role of the support in parasitic moisture sorption and the capture capacity of two amidines, DBU and DBN. A thermodynamic framework for evaluating the CO2 capacity under different capture and regeneration conditions has been developed to show that each amidine is an optimal sorbent for different conditions. We have also used quantum mechanical calculations to explore the range of CO2 capacities that might be possible from functionalized amidines. These functional groups modify the electronic and geometric environment around the CO2 binding site through steric hindrance, hydrogen bonding and electron withdrawing/donating effects. We will discuss how these results could be integrated in developing new CO2 sorbents.
John Kitchin completed his B.S. in Chemistry at North Carolina State University. He completed an M.S.in Materials Science and a PhD in Chemical Engineering at the University of Delaware in 2004 under the advisement of Dr. Jingguang Chen and Dr. Mark Barteau. He received an Alexander von Humboldt postdoctoral fellowship and lived in Berlin, Germany for 1 ½ years studying alloy segregation with Karsten Reuter and Matthias Scheffler in the Theory Department at the Fritz Haber Institut. Professor Kitchin began a tenure-track faculty position in the Chemical Engineering Department at Carnegie Mellon University in January of 2006. At CMU, Professor Kitchin’s research focuses on CO2 capture, adsorption behavior, and electrochemical energy conversions. He is coordinating a major research effort within the National Energy Technology Laboratory Institute for Advance Energy Solutions (NETL-IAES) in CO2 capture, sequestration and risk management that includes more than 25 faculty members and theirgraduate students. Professor Kitchin also uses computational methods to study adsorbate-adsorbate interactions on transition metal surfaces, which is funded by DOE-BES. Finally, his research group is developing electrochemical energy conversion technologies including fuel cells, electrochemical gas separations and hybrid hydrogen generation/CO2 sorbent regeneration systems. He was awarded a DOE Early Career award in 2010 to investigate multifunctional oxide electrocatalysts for the oxygen evolution reaction in water splitting using experimental and computational methods.
Wednesday, March 31
8:15 a.m., 129 DeBartolo Hall
"Adsorption of Gases in Nanoporous Materials: Equilibrium and Kinetics"
Dr. Maria Calbi, Department of Physics
Southern Illinois University, Carbondale
Adsorption phenomena on surfaces have been extensively investigated based on the presence of thermodynamic equilibrium between the external gas in contact with the surface and the adsorbed film. In nanoporous structures, however, the actual observation of the expected equilibrium properties (such as the total gas uptake for example) may strongly depend on how and how fast that equilibrium is reached, generally referred to as adsorption kinetics. Exploring the interplay between equilibrium and kinetics in a nanoporous structure is essential to fully understand and take advantage of its adsorption capacity, and to design nanomaterials tailored to provide specific applications. In particular, the investigation of the kinetics of adsorption (including the adsorption rates of different species) has always been the leading step to assess the separation efficiency of a sorbent for potential applications.
We present here a series of results concerning the kinetics of adsorption of different gases and mixtures on different regions of a carbon nanotube bundle. Carbon nanotubes have recently emerged as promising materials for separation and membrane applications, and assessing their properties for such purposes has become an imperative need. In addition, since these nanostructures have several kinds of adsorbing surfaces (including pores and inhomogeneous external surfaces) our results are also relevant to many other sorbents that typically have only one type of these surfaces. By implementing a Kinetic Monte Carlo algorithm to follow the time evolution of the gas uptake we are able to explore an interesting variety of kinetic phenomena, identifying the elemental processes responsible for the observed behavior. As a result, we have provided useful insight on long-standing controversies on the adsorption behavior of these structures (including direct explanation of several adsorption kinetics experiments), and also identified a new potential mechanism for gas separation.
Born and raised in Argentina, Prof. Calbi earned her PhD degree in physics at the University of Buenos Aires in 2000. She then completed her training in condensed matter physics at the Pennsylvania State University where she made her first contributions in the theory of gas adsorption on solid surfaces. In 2003, she joined the Physics Department at Southern Illinois University Carbondale where she was recently promoted to Associate Professor. One of her main interests lies on determining the ability of a variety of nanostructures to act as adsorbents by developing models and methods that can provide a basic understanding of the adsorption processes and phenomena (equilibrium and kinetics) in nanoporous materials. From a practical perspective, the goal is to provide a rational basis for assessing the performance of a nanostructure for specific adsorption applications that can be used, at the same time, to guide the design of new materials for such uses. Prof. Calbi’s research projects have been continuously funded by external agencies since 2005 and are currently supported by the National Science Foundation. She is the recipient of a CAREER award from that agency, and was also recently honored with the “Presidential Early Career Award for Scientists and Engineers” (PECASE).
Wednesday, March 17
8:15 a.m., 115 DeBartolo Hall
"Microstructural Control to Achieve High Performance MFI Type Zeolite Inorganic Membranes"
Dr. Jungkyu Choi,University of California, Berkeley
Department of Chemical Engineering
It has been addressed that a robust, reliable fabrication of defect-free zeolite membranes are critical to contribute considerably to energy-saving in separation processes as alternative to conventional cost-intensive counterparts (distillation, crystallization, etc.). Therefore, much research has been focused on the field of zeolite membranes with respect to control of pore orientation and film thickness on diverse supports. We developed a reliable methodology, i.e., so called secondary growth, which leads to achieving preferentially out-of-plane oriented zeolite films reproducibly, in contrast with other approaches that often fail. In the first part of this presentation, I will demonstrate the robust protocol to synthesize uniformly a-oriented MFI films: an a-oriented seed layer was achieved and the subsequent hydrothermal growth of the seed layer led to the uniformly a-out-of-plane oriented MFI film.
The performance of a-oriented MFI films, however, was very poor unlike our expectation. This could be attributed to the presence of non-zeolitic parts that are known to be detrimental to membrane performance. In spite of many researchers’ substantial efforts to avoid them, the inevitable defect formation and accordingly poor separation performance led us to explore a totally different approach deviating from a general belief that the slow heating rate would avoid defect formation. In the second part, I will introduce a simple but surprisingly effective way to eliminate or at least reduce the non-zeolitic parts, especially grain boundary defects, by a using rapid thermal processing (RTP) on as-synthesized c-oriented MFI films. The separation performance of such membranes were significantly improved for both aromatics (~ 120 p-/o-xylene separation factor) and linear/branched alkanes (~ 34 n-/i-butane separation factor), as compared to that of conventionally calcined ones. This was attributed to the lessened density of grain boundary defects between MFI polycrystalline grains as evidenced in Fluorescence Confocal Optical Microscopy (FCOM) images, though other microstructural characteristics were virtually identical to conventionally calcined films. The RTP strategy was further successfully applied to c-oriented MFI membranes made on industrially desirable stainless steel tubes leading to unprecedented separation performance (~ 28 p-/o-xylene separation factor).
Dr. Jungkyu Choi received a B.S. degree in Chemical Engineering from Seoul National Universityin 2003 and a Ph.D. from the University of Minnesota in 2008. His dissertation addressed the synthesis, characterization, and application of zeolite membranes in the group of Professor Michael Tsapatsis. Dr. Choi has been a postdoctoral fellow in the Iglesia group at the University of California, Berkeley since 2008, where he is developing frequency modulation flow protocols to measure the dynamics of diffusion, adsorption, and chemical reactions within microporous solids.
Monday, March 1
8:15 a.m., 115 DeBartolo Hall
"Nanocomposite Materials for Environmental Applications"
Dr. Mary Laura Lind, Civil and Environmental Engineering Department
University of California Los Angeles
This talk will discuss recent work on advanced nanocomposite membrane materials. Understanding the effects of nanoscale interactions on bulk material properties enables the design of novel materials with advanced functionalities. Within the context of sustainable engineering, advanced nanomaterials allow improved industrial separations (sorbants, catalysts, membranes), advanced water purification (low energy desalination, non-toxic biocides), environmental remediation (CO2 sequestration, contaminant cleanup), and renewable energy production (fuel cells, photovoltaics, osmotic power). Inside this framework, we explore the introduction of molecular-sieve nanoparticles into thin polymeric films and the resulting effects on water and ion transport when tested as reverse osmosis (RO) membranes. These "thin film nanocomposite" (TFN) membranes have the potential to address numerous limitations of current RO technology, including eneergy demand, solute selectivity, membrane stability, and fouing resistance. We have developed mechanistic insights about how nanoscale interactions and structures influence the macroscopic material properties and we are using this knowledge to create new multi-functional membrane materials. Results will be presented that examine how changes in polymer chemistry, nanoparticle size, and molecular-sieve pore size work in concert to determine the resulting nanocomposite membrane chemical structure, physical morphology, interfacial properties, and separation performance. This talk will survey several of the most important unanswered questions, the methods we propose to find answers, and possible extensions to new applications.
Dr. Mary Laura Lind is a California Nanosystems Institute Pioneer Postdoctoral Fellow at the University of California Los Angeles working with Prof. Eric M.V. Hoek in the Civil and Environmental Engineering Department. Dr. Lind received her Ph.D. in Materials Science from the California Institute of Technology and her B.S. in Chemical Engineering from Yale University.
Tuesday, February, 23
3:30 p.m., 131 DeBartolo Hall
"Nanoporous Inorganic Membranes for Energy and Environment Applications"
Miao Yu, Department of Chemical and Biological Engineering
University of Colorado, Boulder
Nanoporous membranes have shown great potential on separating mixtures in an energy-efficient way. Both energy-related mixture separations, such as natural gas purification and alcohol/water separation, and environment-related separations, such as CO2 capture and water treatment, have been widely investigated using membrane based separation processes. Very promising results have been obtained. For example, high quality SAPO-34 zeolite membranes (0.38 nm crystal pores) separated CO2 from CH4 efficiently up to pressure drop 7 MPa with separation selectivity higher than 50; all-silica form MFI zeolite membranes(0.55 nm crystal pores) separated ethanol from water with a separation selectivity higher than 100. My research work concentrates on two types of nanoporous inorganic membranes: zeolite membranes and dense, vertical-aligned carbon nanotube membranes.
With uniform, molecular-sized pores and excellent stabilities (chemical, thermal and mechanical), zeolites/molecular sieves are perfect membrane materials to realize separations by molecular sizes. However, it is a big challenge to make thin, defect-free zeolite membranes because of the polycrystalline feature of zeolite membranes and thus inevitable intercrystalline pores/defects; sparsely distributed (several volume percent), nanometer-sized defects (< 5nm) could essentially “kill” a zeolite membrane. Various methods, including optimizing hydrothermal growth conditions, matching crystal growth with porous supports and selectively blocking defects etc., have been used to minimize defects amount and defects sizes in zeolite membranes. To evaluate the efficiency of these methods, microstructure change of zeolite membranes must be known before and after. This requires understanding of the microstructure of zeolite membranes. One direction of my research work is focused on understanding 3 aspects of the microstructure: What is the percentage of flow through defects? What are defects sizes? Is the microstructure rigid or flexible and could we manipulate the microstructure? My answers to these questions will be given in the talk.
Carbon nanotubes (CNT) are emerging membrane materials. One main motivation of preparing carbon nanotube membranes is the predicted high fluxes in CNTs by molecular dynamics. The predicted high fluxes have been experimentally confirmed using composite CNT membranes, which use polymeric or inorganic sealing materials between CNTs. The previous composite CNT membrane preparation procedures are complicated and <3% of the composite CNT membranes are permeable. This means >97% of membrane area is impermeable! Towards practical application of CNT membranes, we developed a simple technique to fabricate high volume density (~ 20vol.% CNTs), aligned CNT membranes. No sealing materials are necessary because pores between CNTs have similar sizes as CNTs. This introduces extra transport pathway. Structural characterization and size exclusion measurements indicate high quality of dense CNT membranes with membrane cut-off pore size ~ 3 nm. Nitrogen permeability through dense CNT membranes is 4 to 7 orders of magnitude higher than previous composite CNT membranes due to much denser CNT packing and extra transport pathway between CNTs. Potential applications of dense CNT membranes include water nano-filtration, air purification and high flux gas separations.
Dr. Miao Yu is a research associate in the Department of Chemical and Biological Engineering at the University of Colorado at Boulder. He received his Ph.D. in Chemical Engineering from the University of Colorado at Boulder in 2007. Prior to being a Ph.D. student at the University of Colorado at Boulder, Dr. Yu was a Ph.D. candidate in Chemical Engineering at the University of Minnesota in 2004. His research focuses on synthesis, characterization and novel applications of nanoporous inorganic membranes, applications of atomic layer deposition (ALD) and molecular layer deposition (MLD) and dye-sensitized solar cells (DSSC).
Tuesday, February 16
3:30 p.m., 127 Nieuwland Science Hall
"Self-Assembled Block Copolymer Thin Films
Used As Filtration Membrane"
Dr. William A. Phillip, Department of Chemical Engineering
Current ultrafiltration membranes are made using a phase separation technique. This standard technique results in a pore structure that consists of a polydisperse distribution of pore sizes. Among this distribution, the larger pores can comprise any desired separation of solutes from solution. The fabrication of filtration membranes with a monodisperse pore size will be discussed in this talk. These novel membranes take advantage of the self-assembly of block copolymers. Block copolymers are macromolecules composed of two or more chemically incompatible polymers (blocks) covalently bonded together. Depending upon the relative amounts of each block, the copolymer forms different ordered structures 5-50 nm in scale. The structure of interest to this work is polylactide (PLA) cylinders surrounded by a continuous polystyrene matrix. Selectively etching the PLA block produces monodisperse pores, which can improve the rejection of dissolved solutes. Controlling the copolymer self-assembly during the membrane fabrication process as well as the application of these membranes will be discussed.
William Phillip is currently a postdoctoral research associate working in Menachem Elimelech’s research group at Yale University. He joined the Elimelech group after completing his Ph.D. in Chemical Engineering at the University of Minnesota, where he worked with Ed Cussler. The research focus of his graduate studies was the use of self-assembled block copolymer thin films to perform selective membrane separations. In his postdoctoral work, an interest in membrane-based separation research continues with a focus on membrane-based water purification technologies, and applying them to improve processes at the water-energy nexus.