Synthesize Highly Reactive Subnano-Sized Zero-Valent Iron using Smectite Clay Templates
Zero-valent iron is a reactive and powerful reducing agent capable of breaking down toxic compounds. More recently, nanoscale ZVI has emerged as a remediation technology used to degrade toxic chemicals. The nanoscale material (10-100 nanometer particle size) is often preferred because it has significantly more surface area than standard ZVI, which makes nano-ZVI considerably more reactive. This increase in reactivity enables more efficient remediation. The emergence of ZVI as a preferred material for remediation processes and the acceptance of nanoscale ZVI because of its increased efficiency, suggest that even more efficient ZVI could gain acceptance if all other factors remain equal or are more favorable.
Description of Technology
MSU’s invention is a composition and method for producing sub-nanoscale ZVI. Existing (nano-scale) sizes of ZVI range from 10-100 nm. Production of the sub-nanoscale particles are enabled without subsequent aggregation by using clay, which has layered surfaces that provide a large amount of surface area for binding small iron particles and preventing their aggregation. The resulting product is more reactive because of the increased surface area per particle volume – a purely dimensional effect resulting from the small particle sizes. MSU’s sub-nanoscale ZVI can be used simultaneously as a reactive barrier, adsorbent, and contaminant reductant. Presently, materials used as reactive barriers are unable to provide all three functions.
- Sub-nanoscale ZVI enables more efficient remediation: The increased surface area provided by the sub-nanoscale particles provides significantly more reactive sites for recalcitrant contaminants to bind.
- Higher efficiency could enable cost savings: Because the compounds are expected to be 10 to 100 times more reactive and efficient than nanoscale ZVI, it is anticipated that significantly less iron material will be needed for remediation processes using MSU’s invention.
- Enables a multi-functional reactive barrier: The properties of the smectite clay with the sub-nanoscale ZVI enables the material to be used simultaneously as a reactive barrier, adsorbent, and contaminant reductant. Presently, materials used as reactive barriers are unable to provide all three functions.
- Materials are reactive with a broad range of contaminants: MSU’s materials can react with a broad range of substances, making it more broadly applicable as a remediation solution.
This invention is useful in applications for which nanoscale ZVI is presently used, including wastewater remediation, groundwater remediation, and soil remediation. The ZVI provided by this invention has been demonstrated to be highly effective for decontaminating known chlorinated and perfluorinated organic contaminants (and is anticipated to be effective for many other compounds as well).
Hui Li, Cheng Gu, Stephen Boyd
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Michigan State University