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Lehigh research on display at national convention

With the American Institute of Chemical Engineers (AIChE) national convention right around the corner, students and faculty from the department of chemical engineering are gearing up to present their research to peers and colleagues from across the country.

Prof. Jim Gilchrist and students prepare for the AIChE conference.

This year marks the 100th anniversary of the organization, founded in Philadelphia in 1908. A century later, the group’s annual meeting returns to the City of Brotherly Love, November 16-21.

At this landmark point in the history of the organization, a host of Lehigh engineers including graduate students, post-docs, and faculty, and staff will be presenting their work at the conference. (A full list of Lehigh participants is provided below.) Professors William Luyben, James Gilchrist, Hugo Caram, Shivaji Sircar, Mayuresh Kothare, Israel Wachs, Ian Laurenzi, and Mark Snyder of the chemical engineering department, Chris Kiely, Charles Lyman, and Xuanhong Cheng of the material science and engineering department, Arup SenGupta and Derick Brown of the civil and environmental engineering department, and Bruce Koel, Interim Vice President and Associate Provost for Research and Graduate Studies and professor of chemistry and their students will be participating in the convention.

The teams that Lehigh is sending to the meeting will be covering a variety of topics. Research areas include (but are not limited to) global warming, water treatment, fuel cells, gasification, microparticles, nanoparticles, DNA technology, granular flow, and a number of different methods of catalysis. Such research creates new and more efficient manufacturing and development processes, and makes current processes safer in areas such as energy, plastics, textiles, fuels, the environment, and pharmaceuticals.

These participants will also be joined by the undergraduate Chem-E car competition team who placed fifth in the regional race in April and qualified to compete at the national level.

A November to remember

Graduate student Pisist (Pao’) Kumnorkaew has quite a month on his hands; not only will he be giving a presentation on his research at the convention, but his team’s work is also featured on the cover of the upcoming edition of Langmuir magazine, a publication of the American Chemical Society.

Kumnorkaew is advised by P.C. Rossin Assistant Professor of Chemical Engineering, James Gilchrist, and works closely with Nelson Tansu, P.C. Rossin Assistant Professor of Electrical and Computer Engineering, and Yik-Khoon Ee, a research assistant in electrical and computer engineering. Their combined efforts support an NSF-funded project to improve the function of light-emitting diodes (LEDs). Kumnorkaew is developing a new coating for LEDs that increases light emission by up to 300% by increasing the refraction (bending) of the light rays.

If you own a cell phone, calculator, digital watch, or a computer or television with a liquid crystal display, chances are the display is lit using a series of LEDs. Increasing the efficiency of an LED means more light from the diode and producing it by using less energy. The more effective LED could replace incandescent and fluorescent light bulbs in general use and could also be used in traffic lights, low voltage landscape lighting, automotive lighting, and flashlights. Appliances that use LEDs over the more traditional forms of lighting will consume less energy.

The invention requires settling a silica and polystyrene microlens array onto the light-emitting area of the LED. These tiny lenses with a diameter of less than a millimeter increase light refraction and therefore the efficiency of the diode. The single layer of silica and polystyrene is deposited onto the surface of the LED. By adding heat, the silica particles can be partially buried in the polystyrene layer creating a lens that refracts light.

One of the main points of Kumnorkaew’s new design is an emphasis on the deposition rate and angle. The blade with which Kumnorkaew layers the silica in the polystyrene layer can be oriented at different angles to change the way that the silica particles align in the polystyrene. The speed at which the substrate layer is pulled under the blade can be controlled as well. Maximizing the light refracted in the lens requires deposition of a single crystalline monolayer of silica particles, so changing either or both of these conditions can create a more desirable effect.

The size of the microlens and the stability of the lens structure are sensitive to the silica and polystyrene nanoparticle concentrations. "Too much or too little of the nanoparticles will only increase the instability of the monolayer," says Kumnorkaew. The particles must align correctly in order to maximize refraction, so by controlling the exact amount of nanoparticles in the monolayer, the coating will be more or less efficient.

Not only does the coating increase the amount of light, but the new method is cheap and very fast for LED production," Kumnorkaew says. The technique simply requires a humidity-controlled environment, and an apparatus for positioning the blade and moving the substrate layer. This process for deposition of silica in the polystyrene can easily be scaled up for high throughput industrial processing.

Kumnorkaew’s research is important because while an LED may give off more light than an incandescent bulb, and does not pose the environmental concern that the mercury vapor does in fluorescent lamps, the light is not as efficient as that emitted by either of the more common light sources. A scientist are working to improve the efficiency of the LED because it has the potential to be energy efficient, leaves a small environmental footprint, and can be cheaply and easily produced.

This is Kumnorkaew’s fourth year at Lehigh and his second year working on this particular project. He earned his bachelor’s and master’s degrees in Thailand, and was able to come to Lehigh for his Ph.D. through the receipt of one of Thailand’s coveted Royal Thai Scholarships. Participants in the highly-competitive and highly-selective Royal Thai scholars program are chosen based on GPAs, a nation-wide exam, and an interview. Kumnorkaew’s area of interest is in nanotechnology and coatings.

Along with five of his colleagues from Professor Gilchrist’s lab, Pao will join a large group of Lehigh students and faculty members at the upcoming meeting, as below. For more information on the conference itself, please visit the AIChE website.

Session: Advances in
Title: Hexane Isomerization In a Reverse-Flow Chromatographic Reactor
Authors: Brad Carnish, Hugo Caram

Session:
Session in Honor of Professor Kamalesh Sirkar
Title: A New Hybrid Ion Exchange-Nanofiltration (HIX-NF) Separation Process for Energy Efficient Desalination: Process Concept and Laboratory Evaluation
Authors: Sudipta Sarkar, Arup K. Sengupta

Session: New Materials for Inorganic Contaminants
Title: Hybrid Ion Exchanger (HIX): Characterization and New Application Opportunities
Author: Arup K. Sengupta

Session: Distillation Modeling: Reactive and 3-Phase Systems
Title: Dynamic Control of a Column / Side-Reactor Process
Authors: Devrim B. Kaymak (Istanbul Technical University, Turkey), William L. Luyben

Session: Organic Contaminants in Water
Title: Relationship Between Micellar and Hemi-Micellar Processes and the Bioavailability of Surfactant-Solubilized Hydrophobic Organic Compounds
Author: Derick G. Brown

Session: A Century of Surface Science and Catalysis II
Title: Toward Ultimate Selectivity: Site-Directed Chemistry and Catalysis at Pt-Sn Alloy Surfaces
Author: Bruce Koel

Session: Nanostructured Biomaterials
Title: Nanoporous Polyelectrolyte Multilayers: Biomimetic Surfaces for Corneal Epithelial Cells
Authors: Christina Hajicharalambous, Xiaoxia Sheng (MIT), William Hix (Virginia Tech), Magdalena Swierczewska, Michael F. Rubner (MIT), Padma Rajagopalan (Virginia Tech)

Session: Student Poster Session: Catalysis and Reaction Engineering
Title: The High Temperature Water-Gas Shift Over CrO3/Fe2O3 Catalysts
Authors: Christopher Keturakis, Israel E. Wachs, Marco Daturi (Laboratoire Catalyse et Spectrochimie, France


-Christine Rapp

Posted on Friday, November 14, 2008

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