Development of Stabilized Zero Valent Iron Nanoparticles for Environmental Remediation Using Fractioned Humic Acid

Abstract

Nanosized zero valent iron (NZVI) is a new technology used for the treatment of contaminated water, soil, and sediment. Remediation by NZVI of subsurface contaminants is conducted by the injection of NZVI into the contaminated area, however, there are challenges when applying NZVI in the subsurface. These challenges include aggregation, low mobility, and environmental and ecological risks. Research has been conducted to modify the surface properties of NZVI using different coatings to combat these problems. However, these coatings usually involve synthesized chemicals and have only dealt with one or two of these challenges. There is a need for the development of coated NZVI that is low-cost, stable, environmentally compatible, reactive and has controlled mobility. The focus of this research is to use size-fractioned natural humic acid to coat the surface of synthesized NZVI and to test their effects on the NZVI stability under systematically design chemistry conditions. The results from this study showed that humic acid coating, particularly small size fractions of humic acid, could significantly increase the stability of NZVI under extremely high NaCl concentrations and moderate CaCl2 concentrations. The extended Derjaguin, Landau, Verwey and Overbeek (XDLVO) theory was applied to correlate the particle-particle energy interactions to NZVI stability.