Fellow: Jay Thompson
Advisor: Achintya Bezbaruah, Ph.D., Assistant Professor, Department of Civil Engineering, North Dakota State University
Matching Support: Advisor’s salary and tuition waiver (In-kind matching)
Degree Progress: M.S. in Environmental Engineering expected in May 2008. 

Pesticide contamination of groundwater remains an ongoing area of concern. One promising pesticide remediation technology is reductive dechlorination by iron filings or powder. This technology has been successful in both the lab and field. However, limitations inherent in this process have limited its use.

Recent research has shown that nanoscale zero valent iron (nZVI), with its high surface area and reactivity, can overcome many of these limitations. Although particle properties can vary greatly with synthesis method, typical particles have diameters less than 100 nm. This property results in extremely high specific surface area, which greatly speeds reactions and can eliminate potentially harmful byproducts. Additionally, nZVI can be injected directly into an aquifer, eliminating the need for the expensive excavation associated with iron filings.

Research completed with support of the 2007 NDWRRI program has successfully characterized the synthesized nZVI and described pesticide (alachlor) degradation as a pseudo-first order reaction. However, the proposed model does not account for changes in nZVI surface chemistry, due to oxidation and possibly boron content. This research will attempt to create a more mechanistic model that can be applied to a broader set of applications. Further, environmentally-benign, alginate-based delivery technologies will be evaluated for agricultural applications.

Project objectives:

1. Synthesize and characterize nZVI. Characterization techniques include X-ray diffraction (XRD), transmission electron microscopy (TEM), and BET surface area analysis. Complete
2. Conduct kinetic degradation trials on the selected pesticides with both nano and micro scale iron. Compare reaction kinetics and byproducts. Complete
3. Fully characterize the surface composition of manufactured microscale iron, manufactured nanoscale iron and borohydride synthesized nanoscale iron by X-ray photoelectron spectroscopy (XPS). Mathematically describe the pseudo-first order reaction rate constant in terms of surface area, surface chemistry and degree of agglomeration. In progress
4. Assess the utility of nanoscale iron entrapment and encapsulation (E/E) for pesticide remediation. Compare the kinetic and hydraulic characteristics of E/E nZVI with bare nZVI. In progress

Progress:

The nZVI characterization and kinetic trials proposed in the 2007 NDWRRI program are complete. A manuscript describing this work is currently in review for publication. Kinetic trials on E/E nZVI are underway; preliminary results are promising. Column studies will begin immediately upon the completion of kinetic trials. XPS samples will be sent for analysis very shortly.

Significance:

The proposed research will be useful for the development of an nZVI permeable reactive barrier with improved hydraulic characteristics. This is significant because research on practical, inexpensive applications of nZVI is scarce. Furthermore, the proposed (and completed) research may have applications in the development of an inexpensive on-site pesticide waste treatment system. Such a system could potentially treat low-volume, high-concentration pesticide wastewater and rinse water much more economically than the centralized treatment system used presently.

Presentations:

     Jay Thompson, Achintya N. Bezbaruah, Bret J. Chisholm, 2007, Rapid Dechlorination of the Herbicide Alachlor by Zero Valent Iron Nanoparticles. ISNEPP 2007, Nanotechnology in Environmental Protection and Pollution, 11-13 December. Ft. Lauderdale, FL (Presentation)

     Jay Thompson, Achintya N. Bezbaruah, Bret J. Chisholm, 2007, Iron Nanoparticles for the Treatment of the Herbicides Atrazine, Alachlor and Dicamba in Groundwater. 2 nd International Conference on Environment, 2-5 August. Athens, Greece (Presentation)

     Jay Thompson, Achintya N. Bezbaruah, Bret J. Chisholm, 2007, Laboratory Scale Study to Determine the Effectiveness of Iron Nanoparticles for Selected Pesticide Remediation. 2007 AWRA Summer Specialty Conference, Emerging Contaminants of Concern in the Environment: Issues, Investigations, and Solutions, 25-27 June. Vail, CO (Poster)