HANOVER, N.H. - If you ask research materials engineer Dr. Emily Asenath-Smith to choose her favorite research element among air, fire, water and earth, she’d say, “Water is key to all life and has been a passion of mine for years — we all need to stay hydrated.”
Asenath-Smith’s determination to develop low energy solutions to remediate water led her to develop U.S. Patent No. 11,298,689, awarded April 12, 2022, for “Multi-spectral photocatalytic compounds.”
Invented at the U.S. Army Engineer Research and Development Center’s (ERDC) Cold Regions Research and Engineering Laboratory (CRREL), Asenath-Smith’s creation is a new material which uses solar energy to remove harmful dissolved molecular contaminants, which can include trace amounts of pharmaceuticals, pesticides and personal-care products that persist even after water has undergone treatment.
She applied her expertise in bio-inspired material synthesis and properties, surface science, adhesion, energy transfer materials and her Cornell University doctorate degree in materials science & engineering, along with her passion for water, to develop this new material with far-reaching potential in multiple scenarios.
Safer water for Soldiers
“The U.S. Army needs robust, low-cost systems to enable them to reuse 100% of their water for operations in remote and contingency locations,” said Asenath-Smith. “To avoid the concentration of molecular contaminants — which include molecules that are endocrine disruptors, carcinogenic and toxic — the system must remove all contaminants.”
“In the context of my research at ERDC-CRREL, such water resources are critical to successful missions of our military all over the globe,” she continued. “Transporting water is both costly and dangerous. The military needs robust and versatile systems for treating and purifying water in place. If the military had such a system, they could set up a base in a remote or contested area and only have to stock it with water one time. The cost savings and risk reduction would be huge.”
Noting current challenges, Asenath-Smith said, “Humans have had a widespread impact on water supplies on this planet, both above and below the ground. There is little, if any, uncontaminated water left on our planet, and many of these contaminants are not removed by traditional water treatment methods.”
She added that as water runs through the traditional cycle of extraction, use, treatment and release, persistent contaminants are up concentrated. The environmental and public health consequences are concerning, and the scientific community is working diligently to develop solutions to remove molecular contaminants from water using adsorbent methods as well as advanced oxidation approaches.
Team improving recycling processes
The invention team members included research chemist Emma Ambrogi, who is currently a student at Dartmouth College, and research environmental engineer Jonathon Brame, formerly an ERDC Environmental Laboratory employee who is now at the U.S. Army Combat Capabilities Development Command as team lead for Basic and Applied Research.
The team developed the new material formulation during an applied research program which ran from fiscal years 2016-2019.
“The reuse of wastewater from various sources, known as water recycling, has been employed for non-potable uses for several decades. In contrast, the reuse of water for potable applications is a developing area that requires higher levels of decontamination and purification than standard wastewater-treatment processes,” Asenath-Smith said.
She added that one particular challenge in potable water reuse is the removal of trace amounts of contaminants.
“These contaminants tend to be small, organic molecules that persist through conventional wastewater treatment processes, thus meriting their identity as recalcitrant contaminants. Even in trace amounts, these contaminants can have negative effects on the environment and aquatic life as well as on public health,” Asenath-Smith said.
How it works
Photocatalysts are defined as materials which accelerate reactions when exposed to light. In this case, the reaction of interest is the decomposition of molecular contaminants in water. Many photocatalysts are only responsive to ultraviolet (UV) light which limits their performance. The material that Asenath-Smith and her team developed has components that respond to UV, visible and near-infrared regions of light, so a larger portion of the solar spectrum can be utilized.
“These patented materials don’t remove contaminants by absorption processes,” Asenath-Smith said. “They use sunlight energy to break down the contaminant molecules into benign by-products.”
“The photocatalysts used are from the class of transition metal oxides and are non-toxic compounds based on earth-abundant materials. The metal-oxide photocatalysts used are zinc oxide, which is ultraviolet active; hematite, which is active in the visible spectrum; and copper oxide, which is active in the near-infrared spectrum. With their optimized formulation, the invented material achieved reaction rates which are greater than the sum of the rates of the individual photocatalysts,” she said, adding that this means the three components are working synergistically to degrade contaminants in water.
Future plans
Asenath-Smith and her team will be recognized later this year in a plaque presentation ceremony by leaders of the ERDC Office of Research and Technology Transfer, which coordinates patent activities for the center.
The next steps for this work are to integrate it into a device so it can be deployed to field scenarios.
Asenath-Smith said, “This invention was for a composition of matter, meaning that we invented a new material. To realize its full potential, the material needs to be integrated into a device, which would allow effluent water to contact the invented material so that contaminants can be degraded. Such a device is best suited as the polishing step in a water treatment train, since it will remove the small molecule contaminants that persist after water treatment is completed. Since this material is a ceramic catalyst that does its work in response to light, it is robust and can be reused indefinitely.”
When asked to share advice to future inventors, Asenath-Smith said, “Teamwork, teamwork, teamwork.”
“The research we do in the ERDC is highly diverse and successful outcomes result from the integration of many perspectives,” she continued. “My team at ERDC-CRREL works on materials science and chemistry, and for this work, we were part of a broader ERDC team that included an environmental engineer, physicist and chemist. With the right team, you can solve huge challenges and have fun along the way.”