2006 Progress Report: Nanostructured Membranes for Filtration, Disinfection, and Remediation of Aqueous and Gaseous SystemsEPA Grant Number: GR832372
Title: Nanostructured Membranes for Filtration, Disinfection, and Remediation of Aqueous and Gaseous Systems
Investigators: Kit, Kevin , Davidson, P. Michael , Weiss, Jochen , Zivanovic, Svetlana
Institution: University of Tennessee - Knoxville , University of Massachusetts - Amherst
EPA Project Officer: Carleton, James N
Project Period: August 1, 2005 through July 31, 2008 (Extended to July 31, 2009)
Project Period Covered by this Report: August 1, 2005 through July 31, 2006
Project Amount: $349,200
RFA: Greater Research Opportunities: Research in Nanoscale Science Engineering and Technology (2004) RFA Text | Recipients Lists
Research Category: Hazardous Waste/Remediation , Nanotechnology , Safer Chemicals
The objective is to develop electrospun nanofiber chitosan membranes, which will have the ability to treat aqueous and gaseous environments by actions of filtration, disinfection, and metal binding. Chitosan is nontoxic and biodegradable, and it has been shown to have beneficial antimicrobial and metal-binding properties. These beneficial properties will be optimized in a nanofiber structure in which the surface area per mass is very high. The central hypothesis for the proposed research is that the ability of these nanofiber chitosan membranes to effectively filter contaminants, kill microbes, and bind harmful metals will be optimized by minimizing the size of the electrospun fibers and maximizing the available chitosan surface area.
Successful electrospinning of pure chitosan from aqueous solution into acceptable fibrous structures was not possible. However, we were able to electrospin fibers from chitosan blends with two synthetic polymers: polyethylene oxide (PEO) and polyacrylamide (PAA). Fiber formation was influenced by the mass ratio of chitosan to synthetic polymer, polymer concentration, solvent, and the blend copolymer used. Addition of 10% PEO (by total polymer mass) or 25% PAA was sufficient to produce a nanofiber morphology. Blend fiber diameters ranged from 140 nm to 2 μm. It was found that increasing PEO content in the blend solutions led to a decrease in fiber diameter and resulted in formation of more uniform fiber mats. Both the mechanical properties and the antimicrobial activities were assessed for the chitosan-PEO blend films. Increasing amounts of PEO led to decreases in the tensile strength and strain at break. However, the lowest strength measured (47 MPa for 50% PEO blend) compares favorably with engineering thermoplastics and this decreased strength should not adversely affect the use of chitosan-PEO fibers in filtration media. Antibacterial properties were tested against Escherichia coli K-12. Antimicrobial activity decreased in the chitosan-PEO blends as the PEO content was increased from 10% to 40%. The magnitude of the decrease was approximately proportional to the increased amount of PEO, However, the blend containing 50% PEO showed a significant increase in activity compared to the 40% blend. Even the least effective blend (40% PEO) still possessed highly effective antimicrobial functionality.
In the second year of this project, we will use the knowledge gained from the production of chitosan membranes with variations in fiber size and morphology, membrane thickness, and fiber composition (Task 1) to determine the effect of these parameters on filtration (Task 2), metal binding (Task 3), and disinfection (Task 4) performance of these membranes. Task 3 will also include structural and chemical characterization of the electrospun membranes (e.g., crystallinity and surface composition), because these properties will likely influence the metal binding and disinfection properties. Optimization of the properties and performance of electrospun chitosan membranes will require a feedback loop. Accordingly, the results of the functional and physicochemical properties characterized in Tasks 2–4 will be fed back to Task 1 in order to produce nonwoven chitosan membranes fibers that have optimal performance.
Journal Articles on this Report : 2 Displayed | Download in RIS Format
|Other project views:||All 13 publications||3 publications in selected types||All 3 journal articles|
||Wongsasulak S, Kit KM, McClements DJ, Yoovidhya T, Weiss J. The effect of solution properties on the morphology of ultrafine electrospun egg albumen–PEO composite fibers. Polymer 2007;48(2):448-457.||
||Zivanovic S, Li J, Davidson PM, Kit K. Physical, mechanical, and antibacterial properties of chitosan/PEO blend films. Biomacromolecules 2007;8(5):1505-1510.||