Iron Nanoparticles for the Treatment of the Herbicides Atrazine, Alachlor and Dicamba in Groundwater


Graduate researchers:Jay Thompson, Achintya Bezbaruah

Project sponsors: USGS/NDWRRI (03/2007-08/2008)


Iron metal has been used for the remediation of contaminated groundwater for about two decades. The most common mode of contaminant degradation by iron is reductive dehalogenation. Typically, iron for remediation is used in the form of filings or microscale powder. In this manner, iron has been used in the field and laboratory to remediate water contaminated with chlorinated ethanes, chlorinated methanes, arsenic, mercury, nitramines, and pesticides. The advantages of iron metal for remediation include its non-toxicity, economy and faster reaction rates than biological processes. However, microscale and larger particles cannot be injected directly into the aquifer. Instead, it is usually deployed in a passive reactive barrier. More importantly, the above reaction has been shown to be surface area dependant. Because of the relatively low surface area of iron filings and powder, reactions may be slow or incomplete, resulting in possibly toxic degradation by-products. With the development of iron nanoparticles for environmental remediation, many of the problems associated with iron filings were resolved. Iron nanoparticles are typically 1-100 nm in diameter. This results in specific surface areas in the range of 18 m2/g to 54 m2/g compared to about 0.05 and 5 m2/g for iron filings and lab-grade iron micropowder, respectively. In addition to their higher surface area, iron nanoparticles are attractive for remediation of various contaminants because of their other unique physiochemical properties that allow even higher reaction rates. Pesticides, including herbicides, insecticides and fungicides, are among the many contaminants successfully treated by conventional iron powder or iron filings. Of particular interest are the heavily used corn herbicide families chloroacetanilides and chloro-s-triazines. In North Dakota, dicamba is also a concern due to its heavy use and high mobility. Sixty percent of North Dakota's population use groundwater for their drinking water source. In rural areas, where pesticide contamination is more likely to occur, 97% of the population depends on groundwater. Protection of this resource is of vital interest to the people of North Dakota. The main scope of this study is to investigate the potential of iron nanoparticles for the cleanup of groundwater contaminated with the common herbicides atrazine, alachlor and dicamba. Specific objectives are to investigate the kinetics of degradation of the selected herbicides by iron nanoparticles and identification of by-products, to compare the kinetics of nanoscale and microscale iron particles and elucidate the nanoscale effects, and to conduct column studies investigating the ability of iron nanoparticles to remediate the selected herbicides in environmentally relevant conditions.