Dissertation/Thesis Abstract

Carbon nanotube-based hybrid filter development: Effective removal of viral and bacterial pathogens from water at low pressures
by Stirgwolt Brady-Estevez, Anna Chandler, Ph.D., Yale University, 2009, 123; 3395083
Abstract (Summary)

The ability to secure clean water is a daily challenge to survival for over a billion people that lack access to this vital resource across the world. It is essential that new water treatment options are made available that empower people to treat their own water in ways that are sustainable and energy-efficient.

The overall goal of this research was to utilize the unique properties of carbon nanotubes, including strength, high thermal stability, antimicrobial toxicity, high surface area, and adsorptive capacity, for development of an optimized point-of-use filter targeting removal of microbial pathogens from water.

The nanotubes were deposited onto porous support membranes to form highly permeable matrices. Current matrix deposition methods enabled higher viral removal for MWNTs in comparison with SWNTs, while staining assays showed the higher cytotoxicity of SWNTs towards microbes. These findings informed design of an improved SWNT-MWNT dual filter that combined low-cost MWNTs for achieving viral removal with a thin upper layer of SWNTs to confer antimicrobial properties for biofilm inhibition.

The adsorption of viruses to the CNT hybrid filters varied with the virus tested and the solution conditions of the water sample to be treated. Viral removal increased with increasing ionic strength, addition of CaC12, reduction of pH below the viral IEP, and reduced fluid approach velocity. Reduction of the viral adsorption was caused by high levels of SR-NOM, alginate, addition of MgCl2, and increasing pH and flux rate. While MS2 was tested on all filters, removal of T4 and PRD1 was also demonstrated for the SWNT-MWNT filter. These low energy filters achieved high viral removal at gravity-driven pressures in comparison with conventional microfiltration systems that attain negligible viral removal.

While complete bacterial retention was shown for all the filters, the SWNT-MWNT filters were more effective than MWNT filters for inactivation of Escherichia coli (Gram negative), Staphylococcus epidermis (Gram positive), and microbes naturally present in river water and wastewater effluent.

This work demonstrates that low-cost CNT-hybrid filters present numerous advantages for point-of-use treatment. Produced by simple deposition-based methods, these filters are suitable for scale-up and future developments could expand their reach to centralized treatment or larger scale operations.

Indexing (document details)
Advisor: Peceia, Jordon
School: Yale University
School Location: United States -- Connecticut
Source: DAI-B 71/02, Dissertation Abstracts International
Subjects: Environmental Health, Public health, Water Resource Management
Keywords: Bacterial pathogens, Carbon nanotubes, Viral pathogens
Publication Number: 3395083
ISBN: 9781109630381
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