2005 Award Winner
Government and Commercial Award Winner
EZVI Zero-Valent Metal Emulsion for Reductive Dehalogenation of DNAPL-Phase Environmental Contaminants
Lead NASA Center:
Kennedy Space Center (KSC)
Government and Commercial
Remediation of halogenated solvents, such as trichloroethene (TCE), halogenated hydrocarbons, other chlorinated solvents, is of great concern due to their toxicity and their persistence in the environment. Halogenated solvents, such as TCE, enter the groundwater and soil environments through improper disposal practices. These halogenated solvents are used by industry as degreasers in the production of dry cleaning fluids, spot removers, insecticides and pesticides, as well as in many other manufacturing processes.
Because of halogenated solvents' wide variety of uses, they have become ubiquitous in the environment. According to the EPA, TCE has been found in a least 852 of the 1,430 National Priorities List sites. When released into the ground, halogenated solvents, such as TCE, will sink through the subsurface soil and groundwater until it is contained by a nonpermeable surface such as bedrock. At this point it will pool and slowly dissolve into the aquifer in which it was released. Halogenated solvents, such as TCE, that have higher densities than water are referred to as Dense Nonaqueous Phase Liquids (DNAPLs). Due to the low solubility of many halogenated solvents, for example TCE's low solubility (1.1x103 mg/L), the pool will continue to contaminate groundwater for extended periods of time. As the groundwater is in constant motion, this pool can contaminate very large areas of the potential drinking water.
Above: Micrograph of nano-ion emulsion.
Breakdown of halogenated solvents in natural environments is very slow and produces other potential harmful by-products that are also regulated by the EPA in Title 40 Code of Federal Regulations. Currently, the maximum contaminant level of TCE acceptable in groundwater established by the EPA is 4-5 µg/L. Six licenses have been granted to use the patented techniques using Emulsified Zero-Valent Iron (EZVI). EZVI is a surfactant-stabilized, biodegradable water-in-oil emulsion with zero-valent metal particles contained within emulsion micelles. EZVI may contain either nanoscale zero-valent iron particles or microscale iron particles that are used to dehalogenate DNAPLs.
However, other zero-valent metal particles and combinations may be used, including various bimetallic particle combinations and, more specifically, iron particles doped with palladium. EZVI was developed to degrade very high concentration halogenated compounds like the cleaning solvents that NASA used ubiquitously during the Gemini and Apollo programs. These solvents, which are now known to be carcinogenic, were often disposed of into the subsurface at a number of NASA Centers. Subsequently, it has become NASA's responsibility to return impacted natural media to as near pristine conditions as possible. The spinoffs into cleaning the environment are manifold and of immense value.
Interview with Dr. Jacqueline W. Quinn, Team Lead, EZVI
When you look back over your NASA career, have opportunities provided by NASA enabled your career success as a scientist? How?
Most definitely! NASA has supported my efforts to return to school for two graduate degrees. Pursuit of these degrees allowed me to work with some amazing professors and helped to mold my research skills.
In what ways do you believe that NASA's approach to R&D and science has not only helped NASA but also mankind?
NASA encourages its scientists to be "out of the box" thinkers, and by doing so the Agency allows for a type of creative explosion. This fostering of non-traditional engineering and science brings about so many useful tools for every day life, from computer programs, polymer coatings and new alloys to even environmental cleanup technologies.
In what ways did the team approach with UCF enhance your project (and your invention)?
Teams in general always enhance an innovation, as everyone sees something the other did not. Our team was particularly effective because we brought together such different expertise. Working with two brilliant Chemistry Professors (Dr. Chris Clausen and Dr. Cherie Geiger), an incredible graduate researcher (Kathy Brooks) and an outstanding Environmental Engineering Professor (Dr. Debbie Reinhart) on the EZVI project was an amazing scientific adventure!
What new discoveries and inventions do you see coming from your current line of research?
Our team is now focused on a bimetallic reactant that is capable of degrading polychlorinated biphenyls (PCBs) that are found on structural paints, caulking or in adhesive binders. The technology is also portable to sediment systems within our environment.