Continuum Theories Combined with Atomistic Information for Electrolyte Transport in Nanometer Channels

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Abstract Proposal Title: Continuum theories combined with atomistic information for electrolyte transportin nanometer channels, Proposal Number: CTS-0625421, Principal Investigator: N.R. Aluru, Institution: University of Illinois at Champaign-UrbanaAbstract:Water and ion transport in nanometer scale channels and pores referred to as nanofluidic orelectrolyte transport plays an important role in determining the functional characteristics of many biological and engineering devices. In this research, the PIs propose to investigate fundamental issues including the development of advanced continuum theories for electrically-mediated transport of liquids and electrolytes through confined nanochannels.From an intellectual merit perspective, the PI's preliminary studies on fluid (water) and ion transport through nanometer channels indicate that the molecular nature of the ion and water are important factors influencing the ion concentrations, velocity profiles and other fluid characteristics. Specifically, the ion-ion, ion-fluid, ion-surface and fluid-surface interactions are significant for fluids/electrolytes confined in nanochannels. As the continuum theories based on the Poisson-Boltzmann and the Navier-Stokes equations account for the various molecular interactions in a mean-field fashion, they fail to predict the fluid/ion characteristics accurately, especially near the channel-fluid interface. Moreover, fluids confined in nanochannels can exhibit anomalous behavior, which cannot be explained by the classical theory. In this research, the PI proposes to develop two new methods namely, continuum with atomistic potential (CAP) and continuum with atomistic viscosity (CAV) to overcome the difficulties with the classical theory. The CAP method, where the basic idea is to obtain an atomistic potential at each point by considering an atomistic box, is used to solve the Poisson-Boltzmann equation to compute the ion concentrations. The CAV method, where the basic idea is to obtain a point-wise viscosity by considering an atomistic box at each point, is used to solve the Navier-Stokes equations to compute the bulk flow. The PI proposes to test the CAP and CAV methods on several examples including four complicated problems where anomalous flow behavior and selective separation of ions has been observed and cannot be explained by the classical theory. The broader impacts of the project include the development of advanced continuum theories for fluid transport in nanometer channels can accelerate the design and development of a number of applications including fuel cell devices, hybrid micro/nanofluidic devices for chemical/biological analysis, nucleic acid and protein transport through nanopores and biomimetic devices for single molecule transport and analysis. The main efforts of this project will result in the education of one new graduate student in the highly interdisciplinary area of computational nanofluidics. The research results from this project will be presented in archival journals and conferences around the world. The fundamentals and techniques developed as part of this project will form the basis for a new interdisciplinary course on computational nanofluidics. Recruitment of women and minority graduate students, recruitment of undergraduate students for REU projects, incorporation of results from this project into summer schools offered at UIUC are some of the other planned activities.