Synthesizing Nanoscale Iron Particles for Rapid and Complete Dechlorination of TCE and PCBs

TLDR

Zero‑valent iron, especially in nanoscale form, is an innovative remediation technology for halogenated organics, enabling reactive walls or direct aquifer injection due to its high surface area and reactivity. The authors present an efficient synthesis of nanoscale (1–100 nm) iron and palladized iron particles. The synthesized particles exhibit a BET surface area of 33.5 m² g⁻¹, roughly 37 times that of commercial Fe powder, and batch studies show rapid, complete dechlorination of aliphatic chlorinated compounds and PCBs at low metal‑to‑solution ratios, with surface‑area‑normalized rate constants 10–100 times higher than commercial iron.

Abstract

Transformation of halogenated organic compounds (HOCs) by zero-valent iron represents one of the latest innovative technologies for environmental remediation. For example, iron can be used to construct a reactive wall in the path of a contaminated groundwater plume to degrade HOCs. In this paper, an efficient method of synthesizing nanoscale (1−100 nm) iron and palladized iron particles is presented. Nanoscale particles are characterized by high surface area to volume ratios and high reactivities. BET specific surface area of the synthesized metal particles is 33.5 m2/g. In comparison, a commercially available Fe powder (<10 μm) has a specific surface area of just 0.9 m2/g. Batch studies demonstrated that these nanoscale particles can quickly and completely dechlorinate several chlorinated aliphatic compounds and a mixture of PCBs at relatively low metal to solution ratio (2−5 g/100 mL). Surface-area-normalized rate constants (KSA) are calculated to be 10−100 times higher than those of commercially available iron particles. The approach presented offers unique opportunities for both fundamental research and technological applications of zero-valent metals. For example, a potential application of the nanoscale particles is to inject the metal particles directly into contaminated aquifers instead of building iron walls.