Date of Award
Summer 8-23-2025
Document Type
Dissertation
Degree Name
Ph.D. in Physics and Astronomy
Organizational Unit
College of Natural Science and Mathematics, Physics and Astronomy
First Advisor
Mercedes M. Calbi
Copyright Statement / License for Reuse
All Rights Reserved.
Keywords
Equilibration, Binary mixtures, Planar nanomaterials, Porous nanomaterials, Binary gas mixtures, Computational physics
Abstract
We present results of a Kinetic Monte Carlo investigation of the adsorption dynamics of binary gas mixtures on planar and porous sorbents, with a focus on identifying and characterizing kinetic processes involved in uptake evolution and how they influence equilibrium conditions. We also investigate varying thermodynamic simulation parameters such as interactions, alkane lengths, partial pressures and pore configurations to determine how they impact these kinetic processes as well as equilibrium properties. This study matters both for better understanding how kinetics and equilibrium are connected and for improving practical techniques in separation applications. For planar surfaces, weak species overshoot kinetic processes were further characterized from previous research works. This overshoot phenomena, defined as the weaker binding species temporarily reaching a higher fractional lattice coverage in uptake than at equilibrium was found to increase in magnitude and duration with increasing total pressure and increasing interactions. This dependence was further confirmed by correlation analysis on time dependent lattice configurations leading up to equilibrium. Overshoots were also characterized and identified in mixtures involving long chain dimer molecules mixed with monomer molecules. It was found in these mixtures that early adsorption rates and overshoots were influenced by binding energy per site and also influenced by dimer on lattice transitions from flat to transverse states. The monomer species overshoot magnitude was observed to be more sensitive to changes in total pressure and was found to leave the lattice faster for pressures resulting in total monolayer coverage. Finally, adsorption and diffusive competition effects were identified as kinetic processes related to the ii separation and permeance tradeoff found in membrane separations. These effects were characterized for a narrow and wide diffusion pore membrane for both unary and mixture components. With analysis of time dependent concentration profiles it was found that separation was influenced more by diffusivity in the wide pore membrane and influenced more by adsorption in the narrow pore membrane. Time dependent flux measurements confirmed these findings and revealed time dependent separation reversals in the narrow membrane. Time dependent permeance and separation behavior of both wide and narrow components were found to give valuable insight into the equilibration of interconnected wide and narrow components in a hierarchical membrane structure. This structure revealed time dependent coverage reversals in isolated regions directly related to this adsorption and diffusion competition.
JEL— C22, C32, C63
Copyright Date
8-2025
Publication Statement
Copyright is held by the author. User is responsible for all copyright compliance.
Rights Holder
Andrew Torres
Provenance
Received from ProQuest
File Format
application/pdf
Language
English (eng)
Extent
123 pgs
File Size
8.3 MB
Recommended Citation
Torres, Andrew, "Equilibration and Transport of Binary Mixtures on Planar and Porous Nanomaterials" (2025). Electronic Theses and Dissertations. 2660.
https://digitalcommons.du.edu/etd/2660