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Workshop / Seminar

Chemistry PhD Final Defense – Nitesh Kumar, Chemistry Graduate Student

Fulmer Hall
room 150
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About the event

Speaker: Nitesh Kumar

Group: Aurora Clark

Title: Chemical and Transport Phenomena at Biphasic Interfaces

Abstract: Chemical separation processes are often energy intensive and their optimization requires a microscopic level understanding of chemical and transport phenomena. The work described in this dissertation studies the separation methods of solvent extraction. It employs the tools of computational chemistry, graph theory, and persistent homology to understand interfacial chemical processes and transport mechanisms involved in the migration of solute from the aqueous phase, through the interface, and into the organic phase. A complete understanding of these processes involves qualitative and quantitative characterization of molecular adsorption, organization, complexation, and dynamics within different instantaneous liquid phase boundary microenvironments. The dissertation work is categorized into three primary goals: 1.) understanding the intrinsic behavior of the liquid/liquid interface and ion behavior in response to solvent polarity and concentration gradients, 2.) identifying amphiphile assisted phase transport mechanisms of ion complexes, and 3.) development of tools for the understanding of chemical processes at these soft matter interfaces. The first goal involved understanding the impact of adsorption and structural heterogeneity of the interface on ion adsorption, speciation, and dynamics. This was followed by a comparison of ion complexation in the bulk and at the water/oil interface in the presence of electrolyte concentration gradients. The second goal involved studying the generalizability of protrusions as a universal transport mechanism of complex chemical species across the liquid/liquid phase boundary. Towards the third goal, an analysis methodology based on sublevel set persistent homology was devised to analyze adsorbate organization in the presence of highly complex interfacial conditions. The research outlined in the dissertation shows that amphiphiles modulate interfacial adsorption and structural heterogeneity driving molecular competition that impacts ion-specific adsorption, speciation, and molecular dynamics. It is demonstrated that protrusion-based transport mechanisms are responsible for the extraction of a variety of solutes ranging from water to metal-ligand complexes. It is shown that the efficiency of protrusion formation and transport is highly system specific and greatly dependent upon the heterogeneity of molecular interactions within interfacial microenvironments.