Zhang, Tianyu
(2019)
Methods Development for Isolation of Carbon Nanomaterial Degradation Products Under Simulated Conditions Relevant for their Proposed Use in Desalination Membranes.
Master's Thesis, University of Pittsburgh.
(Unpublished)
Abstract
Membrane desalination is a crucial process that enables access to unconventional drinking water sources, such as brackish water and seawater. Membranes are used in the desalination process and critical challenges remain for optimizing performance, most notably biofouling. New innovations in desalination membranes that involve the incorporation of emerging nanomaterials, including carbon nanotubes (CNTs) and graphene, propose a potential solution to alleviate biofouling as well as enhance salt and contaminant rejection. However, carbon nanomaterials (CNMs) have been shown to degrade through chemical and biochemical pathways. While all degradation products have not been identified under all studied conditions, existing literature suggests the possible formation of polycyclic aromatic hydrocarbons (PAHs) and their derivatives. The complete degradation pathways of forming these or similar degradation products (DPs) are not resolved under relevant desalination conditions, including the presence of key components needed to catalyze CNM degradation in these processes, namely relevant enzymes (e.g., from biofilm) and oxidants (e.g., from membrane cleaning). The potential to produce harmful DPs is of concern due to the possible subsequent release to drinking and irrigation waters. This research develops an experimental approach to identify the formation of DPs under simulated desalination conditions as an initial step towards determining their potential formation in desalination processes that use CNM-enabled membranes. Single wall carbon nanotubes (SWCNTs) with characteristics matching those used most in the membrane literature were exposed to model conditions containing various representative chemicals used as membrane cleaning agents (sodium hydroxide, ethylene diamine tetraacetic acid, and sodium dodecyl sulfonate) and Sphingomonas biofilm. Sphingomonas aromaticivoransis was chosen because it has been identified as the dominant species that also initiates biofilm formation on RO membranes and thus, would be in direct contact with the CNT-amended membrane. This study investigated and simulated membrane desalination conditions and developed methods for CNM DP isolation. High performance liquid chromatography (HPLC) was used to characterize degradation of parent PAH molecules and SWCNTs under different conditions. The results herein serve as the foundation for future research to further resolve and identify the chemical structure of DPs with the ultimate goal of safely realizing the potential of the novel CNM-enabled membranes.
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Details
| Item Type: |
University of Pittsburgh ETD
|
| Status: |
Unpublished |
| Creators/Authors: |
|
| ETD Committee: |
|
| Date: |
9 September 2019 |
| Date Type: |
Publication |
| Defense Date: |
6 May 2019 |
| Approval Date: |
9 September 2019 |
| Submission Date: |
15 July 2019 |
| Access Restriction: |
No restriction; Release the ETD for access worldwide immediately. |
| Number of Pages: |
112 |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
Swanson School of Engineering > Civil and Environmental Engineering |
| Degree: |
MS - Master of Science |
| Thesis Type: |
Master's Thesis |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
Membrane desalination, Single wall carbon nanotubes, Carbon Nanomaterial Degradation |
| Date Deposited: |
09 Sep 2019 20:26 |
| Last Modified: |
09 Sep 2019 20:26 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/36881 |
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