Delivery and activation of nano-iron by DC electric field

Abstract

This study demonstrates that by integrating electrokinetics with nanotechnology, the transport of nano-particles can be electrokinetically enhanced for subsurface remediation of tight clay soils where transport time and process efficiency may be an issue. Polymer coated dispersed nano-iron developed at Lehigh University, were used in the experiments reported here. The particles possessed positive zeta-potential below pH 8.3 and remained suspended in solution rather than settling or agglomerating over time as it may occur with bare nano-iron. The injection of nano-iron particles in the lab tests showed a positive shift in the oxidation-reduction potential (ORP) where the effectiveness of nano-iron as an environmental catalyst was demonstrated. The presence of nano-iron and applied electric field together pushed the system ORP to higher positive values than the electrokinetic effects or nano-iron alone. The diffusion of nano-iron without the electrical field showed no activation of the iron, as indicated by little or no change in the ORP. These results showed that nano-iron was both transported and activated by the applied electrical field. The enhanced reaction was analyzed in terms of possible Faradaic processes in clay diffuse double layer, DDL, in presence of electric field.

Keywords:

• Nano-iron
• oxidation-reduction potential
• diffuse double layer
• oscillatory voltage distribution
• transformation