A method for the preparation of stable dispersion of zero-valent iron nanoparticles

Reported herein is a method for the synthesis of fully dispersed and reactive nanoscale particles of zero-valent iron. Polyvinyl alcohol-co-vinyl acetate-co-itaconic acid (PV3A), a nontoxic and biodegradable surfactant, is used in the synthesis of the nanoscale zero-valent iron (nZVI). The addition of PV3A effects three key surface-related changes, which lead to significant enhancements in surface chemistry, particle stability and subsurface mobility potential. These include (1) a reduction of the mean nZVI particle size from 105 nm to 15 nm, (2) a reduction of the zeta (zeta)-potential from +20 mV to -80 mV at neutral pH, and (3) a shift of the isoelectric point (IEP) from pH congruent to 8.1 to 4.5. X-ray photoclectron spectroscopy (XPS) indicates the sorption of PV3A on the nanoparticle surface and also the existence of zero-valent iron (Fe-0) in the nZVI mass. Batch experiments further confirm that the PV3A-stabilized iron nanoparticles are capable of effectively reducing trichloroethene (TCE), as has been observed with previous nZVI materials. No sedimentation of the PV3A stabilized nZVI has been observed for over 6 months, suggesting the formation of stable nZVI dispersion. The appreciably smaller mean particle sizes and ability to remain in suspension should translate into improved subsurface mobility potential. (c) 2007 Elsevier B.V. All rights reserved.