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B.A., Churchill College,
Cambridge University, England
Ph.D., Southampton University, England
Overview
Our research in theoretical physical chemistry centers on the application of statistical mechanics and molecular simulation to understand and predict the behavior of molecules at interfaces. Adsorption, which is the preferential concentration of a solute at an interface, is of vital importance in many scientific and engineering applications. For example, chromatography is widely used for analysis and separation of complex mixtures. Adsorption is also a key step in heterogeneous catalysis, which is used in the manufacture of about 50% of the chemicals produced by US industries. Technological advances in these fields depend, to a significant degree, on our ability to understand and model the molecular-level processes involved.
A central task in gas-solid adsorption is the determination of the adsorption isotherm i.e., the amount of gas adsorbed as a function of bulk concentration, as well as the selectivities of the individual components. Protein adsorption from solution to solid surfaces, on the other hand, is often totally or partially irreversible implying that the isotherm concept is no longer applicable. For these systems, the adsorption kinetics assume prime importance.
Our group has developed models for the irreversible adsorption of macromolecules on solid surfaces. These models capture the essential physics of the adsorption process and we, as well as other groups, have shown that they provide a good description of various experimental data. The models can be extended to allow for two or more components and different transport mechanisms of the adsorbing species to the interfacial region. Changes in conformation of the protein molecules following adsorption can also be incorporated into the model as a spreading process.
One current project involves the development of more realistic molecular models for proteins at solid interfaces that account explicitly for the protein shape and charge distribution. This is necessary to explain a number of experimentally observed phenomena including orientational transitions in the adsorbed layer and the ability of a protein to adsorb on a surface of the same charge. The properties of the model are being determined with brownian dynamics simulation.
In another project, we are attempting to understand at a fundamental level the relaxation processes that occur when the adsorbed molecules can desorb slowly from the surface. The conceptually simple "parking lot" model, which involves the random placement and removal of non-overlapping particles in a space, has complex kinetics. Remarkably, this model is also relevant for the compaction of granular materials - an apparently unrelated process. We are using numerical simulations to examine the behavior of mixtures.
Recent Publications:
1. Olson, C. B. and J. Talbot, "Equilibria and Kinetics of Polydisperse Mixture Adsorption," J. Chem. Phys., 112, 3868, 2000.
2. Talbot, J., G. Tarjus and P. Viot, "The Adsorption-Desorption Model and its Application to Vibrated Granular Materials," Phys. Rev. E. 61, 5429, 2000.
3. Ravichandran, S., J. Madura and J. Talbot,"Brownian Dynamics Simulation of the Initial Stages of the Adsorption of Hen Egg White Lysozyme on Solid Surfaces," J. Phys. Chem. B 105(17), 3610, 2001.
4. Talbot, J. G. Tarjus and P. Viot, "Aging and Response Functions in the Parking Lot Model," European Physical Journal E 5, 445, 2001.
5. Ceyrolles, W. J., P. Viot and J. Talbot, "Heterogeneous Adsorption Kinetics: Mean Field Theory and Simulation," Langmuir (in press, 2001).
My Personal Page
Office Phone: 412.396.6336
Fax: 412.396.5683
Email: talbot@duq.edu |
