- Program Areas
- Energy and Water
- Environmental Restoration
- Munitions Response
- Resource Conservation and Climate Change
- Weapons Systems and Platforms
Periodic Mesoporous Organosilicas as Pre-Concentration Elements for Improved Long-Term Monitoring of Key Contaminants in Groundwater
There are more than 12,000 sites in the United States that are contaminated with one or more compounds related to weapons technologies. These sites include former and current testing and training facilities where waste from weapons manufacture, storage, and reclamation processes has leached into the soil and groundwater. Key contaminants include energetic compounds such as TNT, RDX, and HMX; perchlorate propellants; and degradation products of these contaminants. Long-term monitoring of sites undergoing remediation as well as sites that may eventually require cleanup is critical.
The objective of this project is to develop the systems and methods necessary for applying novel periodic mesoporous organosilicate (PMO) materials to preconcentration of trace levels of key contaminants in groundwater and surface waters in order to improve in-line sensor performance for long-term monitoring. Under an earlier effort, the PMO materials have been shown to enhance the sensitivity of currently available sensor systems by concentrating trace amounts of nitroenergetic targets from large sample volumes (Phase I Final Report). This effort will develop systems and methods for utilization of the materials as in-line preconcentrators for electrochemical detection systems in which a liquid sample is concentrated into a smaller liquid volume as well as for ion mobility spectroscopy (IMS) detection systems where liquid samples are used to provide concentrated vapor phase targets. Materials for the preconcentration of perchlorates are also under development.
PMOs are organic-inorganic polymers with highly ordered pore networks and large internal surface areas. They are synthesized using a surfactant template approach in combination with a phase separation technique to provide organization on both the macro- and meso-scales. This approach facilitates diffusion of targets throughout the entire available surface area. Using a template-directed molecular imprinting approach, a PMO surface can be engineered to have both a large adsorption capacity and selectivity for the target. The binding affinity and capacity of these materials make it possible to concentrate trace levels of targets from a large sample volume while eliminating other contaminants. The targets can be subsequently eluted from the sorbent in a small volume of solvent such as methanol or acetonitrile. This approach is directly applicable to the development of methods and systems for use with electrochemical detection. In parallel, researchers are working to develop methods for utilization of these sorbents in the preparation of samples for IMS-based detection. This application involves sampling from a water source and desorbing the concentrated target into a carrier gas.
New and revolutionary materials, methods, and systems are essential in the realization of technologies to address Department of Defense needs for detecting and monitoring environmental contaminants. The novel porous materials and associated methods developed in this project will provide a cost-effective, regenerable mechanism for the preconcentration and long-term monitoring of energetic materials in groundwater at testing and training facilities. Integrating these materials into existing field deployable systems will enhance the sensitivity of those systems by orders of magnitude. (Anticipated Project Completion - 2013)
Points of Contact
Dr. Brandy White
U.S. Naval Research Laboratory (NRL)
SERDP and ESTCP
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