In the design of efficient adsorbents for the sequestration of toxic molecules and the separation of volatile organic compounds, two important criteria are: high porosity and high density of sorptive sites. The work in this thesis showcases how metal-organic frameworks (MOFs) can be used as porous adsorbent templates where many types of sorptive interactions can be incorporated at high densities. These features can be incorporated by: (1) coordination to the metal-nodes, (2) complexation at the organic linkers, and (3) van der Waals (vdW) interactions within the MOF pores. With the bottom-up construction of MOFs, a wide range of building blocks can be used to engender a single framework to not only exhibit high uptake kinetics and capacity, but also chemoselectively target multiple analytes that require a diverse set of sorptive interactions. The first chapter of this thesis introduces the concept of using MOFs as a template to design efficient adsorbents with high porosities and sorptive-site density. Chapter two describes the successful utilization of a metal node and organic linker in a zirconium-based MOF framework (specifically UiO-66) to chemoselectively capture arsenic species (As(III) and As(V)) from water. This work, however, also revealed that analyte diffusion to all sorptive sites in MOFs can be hindered by small pore apertures. To improve diffusion kinetics, the pores can be enlarged by elongating the organic linkers and/or forming missing-node defects. Chapter three discloses in more detail how the latter strategy also affects the overall pore structure and stability of the UiO-66 framework using a combination of experimental and computational studies. The fourth chapter then focuses on the utilization of the pore environment in another model MOF (ZIF-8) for the separation of linear alkanes. Here, the diffusivities for these hydrocarbons (C5-16) through ZIF-8 thin films were correlated to the level of strong vdW interactions between the aliphatic pores and the incoming analyte. The final chapter summarizes the major findings disclosed in this thesis and suggests new directions in the design of efficient adsorbents.

Creator

• Audu, Cornelius Okatahi

DOI

• https://doi.org/10.21985/n2-8ysa-2w30

Subject

• Chemistry

Language

• en

Alternate Identifier

• http://dissertations.umi.com/northwestern:14503
• etdadmin_upload_636835

Date created

• 2019-01-01

Resource type

• Dissertation

Rights statement

• In Copyright