| NSF Org: |
CBET Division of Chemical, Bioengineering, Environmental, and Transport Systems |
| Recipient: |
|
| Initial Amendment Date: | August 9, 2018 |
| Latest Amendment Date: | August 9, 2018 |
| Award Number: | 1836719 |
| Award Instrument: | Standard Grant |
| Program Manager: |
Christina Payne
cpayne@nsf.gov (703)292-2895 CBET Division of Chemical, Bioengineering, Environmental, and Transport Systems ENG Directorate for Engineering |
| Start Date: | September 1, 2018 |
| End Date: | August 31, 2023 (Estimated) |
| Total Intended Award Amount: | $311,175.00 |
| Total Awarded Amount to Date: | $311,175.00 |
| Funds Obligated to Date: |
|
| History of Investigator: |
|
| Recipient Sponsored Research Office: |
660 S MILL AVENUE STE 204 TEMPE AZ US 85281-3670 (480)965-5479 |
| Sponsor Congressional District: |
|
| Primary Place of Performance: |
Tempe AZ US 85281-6011 |
| Primary Place of
Performance Congressional District: |
|
| Unique Entity Identifier (UEI): |
|
| Parent UEI: |
|
| NSF Program(s): | Interfacial Engineering Progra |
| Primary Program Source: |
|
| Program Reference Code(s): |
|
| Program Element Code(s): |
|
| Award Agency Code: | 4900 |
| Fund Agency Code: | 4900 |
| Assistance Listing Number(s): | 47.041 |
ABSTRACT
Providing sustainable and secure access to potable water is a critical challenge facing this generation. Natural water sources are treated to remove salt, organic matter, and biological organisms. As water demand increases, water sources that require more rigorous pretreatment must be utilized. Polymer membranes are a promising technology for these more rigorous water purification demands, as they selectively transport purified water while rejecting contaminants. Although promising, current membranes face two profound limitations: adhesion and growth of biological films on the membrane, and membrane degradation by chlorine. Both effects reduce membrane performance and increase cost due to the need to clean or replace the membrane. This project will design and test new polymeric membrane materials that retain the performance of commercial membranes, with molecular-level modification of the polymer for increased resistance to fouling by biofilms and decreased degradation by chlorine.
Through an integration of macromolecular and process engineering, this project will investigate how molecular level polymeric design impacts processing, microstructure, and separation performance. Poly(arylene ether sulfone) precursors will be modified using post-polymerization modifications to introduce sulfobetaine zwitterions and a series of crosslinkers. The charge and crosslink densities will be optimized to balance hydrophilicity and water sorption versus swelling that leads to a loss of mechanical stability. Then, (anti)fouling mechanisms for the new membranes will be probed, including the role of surface roughness, hydrophilicity, and charge content on protein adhesion. Also, the influence of systematic changes in charge content on physical membrane characteristics will be studied, including water permeability, salt rejection at various salt concentrations and pressure drops, membrane porosity, free volume, morphology, and separation/process costs. Finally, the charge content and processing conditions will be correlated to membrane longevity, specifically structural integrity at various transmembrane pressure drops for asymmetric membranes, resistance to chlorine-mediated oxidative degradation, and long-term fouling studies. One graduate student will be trained in this project and undergraduate students will be involved in the laboratory work. An educational outreach plan is included that will engage the diverse student body of Arizona State University and the surrounding metropolitan community.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
PUBLICATIONS PRODUCED AS A RESULT OF THIS RESEARCH
Note:
When clicking on a Digital Object Identifier (DOI) number, you will be taken to an external
site maintained by the publisher. Some full text articles may not yet be available without a
charge during the embargo (administrative interval).
Some links on this page may take you to non-federal websites. Their policies may differ from
this site.
PROJECT OUTCOMES REPORT
Disclaimer
This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.
The activities of this project addressed the critical challenge of providing sustainable and secure access to potable water. This was achieved through the development of various polymer membrane designs for water purification in tandem with exploring several water treatment technologies. This project highlighted fundamental design considerations for next-generation membrane development through the bulk introduction of charges (zwitterions – positive and negative ions covalently bound together) on the backbone of poly(arylene ether sulfone) precursors. The unique synthetic approach of this project allowed for tuning the ratio of charges on the polymer backbone to optimize the performance of the membranes for targeted water-feed conditions. The zwitterionic membranes developed in this project were rigorously compared with the workhorse polyamide reverse osmosis membranes and were found to be more resistant to chlorine mediated degradation, more hydrophilic and were less susceptible to long-term fouling. In addition, this project was one of the first in attempting to understand the structure-property-performance relationship of zwitterion-modified membranes for osmotically driven processes.
Another aspect of this project critically examined the versatility of the developed zwitterion modified polymers with an upcoming desalination technology of pervaporation. In this undertaking, a standard membrane casting protocol was developed for dense membranes fabrication in addition to studies that aimed at enhancing the molecular weights of the polymer for mechanical integrity. Notably, the dense membranes demonstrated an excellent performance metric that were able to reject nearly 100% salt at extremely high salt concentrations and displayed one of the highest water treatment capacities putting them in the top 5% of the reported pervaporation membranes in the literature. Furthermore, this work also prompted us to study the fundamental water and salt transport properties in bulk modified zwitterion membranes. The fundamental understanding of these properties opens an avenue for discussion on the transport in charge modified polymers that is pivotal in future investigative studies of molecular level polymeric designs impacting membrane processability and separation performance.
The project also included fabrication of nanofiber membranes with a facile technique of electrospinning for ultra- and micro-filtration water treatment technologies. An emphasis was placed on generating protocols for combining different polymers to develop composite membrane mats. This physical modification to membranes was achieved via tuning the ratio of hydrophilic and hydrophobic polymers that allowed us to change physical and chemical properties of the resulting membranes. The membrane water flux was improved by 1000% and the membrane pore size could be adjusted from nano- to micro-meter scale. The broader implication of this work includes generation of a straightforward protocol of blending polymers to achieve specific properties of membranes that are often adjusted to the characteristics of wastewater in particular communities.
The project also established key testing facilities and apparatus for membrane performance and water treatment experiments. Several objectives of the project were executed on in-house engineered dead-cell filtration and cross-flow filtration setups. Additionally, a cross-flow pervaporation testing facility was created to perform desalination experiments with hypersaline solutions. The development of these facilities helped in achieving the project deliverables and the university in establishing several collaborations with other institutions and national labs. Further, the learnings from this project were translated to other branches of polymer science at ASU to design material systems based on ion-containing polymers for applications like direct air capture of carbon dioxide, oceanic carbon removal, ionene composites and biomedical devices etc.
The engagement in membrane research through this project has been highly beneficial since it has led to opportunities for patenting and accelerating the research for commercialization. The collaboration with industries and government agencies has also strengthened partnerships and acquired funding for further advancement of membrane technology for breakthrough in water purification, clean energy, medical technologies, and various industrial applications. The project produced a number of training opportunities for PhD students, masters students, undergraduate students, and high school students. The project outcomes were integrated into community outreach activities and into the classroom to teach students and community members about water sustainability, polymer science, and the intersection where the two meet. Overall, the membrane research will help in establishing the future studies as a key driver for progress by offering solutions that span scientific, economic and societal domains.
Last Modified: 01/22/2024
Modified by: Matthew Green
Please report errors in award information by writing to: awardsearch@nsf.gov.
