When mercury enters water and sediments it can undergo numerous transformation processes of which mercury methylation is a top environmental concern. Dangerously high concentrations of methylated mercury have been found in fish and waterfowl. Existing methods to minimize the Hg methylation process either tend to let the mercury leak back into the soil; groundwater (as with excavation; landfill techniques) or are not suited for subsurface treatment as they are time-consuming and difficult to control. Auburn inventors have developed an innovative method using stabilized iron sulfide nanoparticles that can effectively prevent the formation of methylated mercury. Without stabilization these particles tend to agglomerate leading to vastly reduced reactivity and particles becoming trapped in the sub-surface soil making them impractical for in situ use. This technology modifies iron sulfide particles at production by adding a very low-cost stabilizer to prevent the nanoscale particles from agglomerating thereby maintaining their high surface area and reactivity. The stabilizer can also be used to control the particle size and dispersibility of the nanoparticles in the subsurface. Tests performed by the inventors with mercury indicate an almost 100% stabilization efficiency meaning that almost all of the mercury immobilized is non-leachable. These and similar stabilized iron nanoparticles can be used for in situ remediation of a variety of inorganic and metallic contaminants. Patent: U.S. Patent 7581902 (Heavy Metals) and U.S. Patent 7635236 (inorganics).
•Uses an inexpensive easily available and environmentally friendly stabilizer. •Allows for easy control of soil mobility. •Treats sub-surface regions where other methods fail (e.g. excavation bioremediation). •Inhibits formation of harmful by-products such as methyl mercury. •Reduces processing time and materials needed thereby reducing costs. •Prevents aggregation of nanoparticles providing superior performance and enabling in situ use. •Allows for application to the entire contaminated zone or for building a sorptive barrierIP Status. •This process has been experimentally verified for mercury.