On the operating mode of bimetallic systems for environmental remediation

C Noubactep

doi:10.1016/j.jhazmat.2008.08.004

Abstract

This letter challenges the concept that Fe 0/Me 0 bimetallic systems enhance contaminant reduction on Me 0 surfaces. It is shown on a pure thermodynamic perspective that any enhancement of contaminant reduction by Fe 0 in the presence of a second more electropositive elemental metal (Me 0) is the result of an indirect process resulting from iron corrosion. This demonstration validates the concept that aqueous contaminant removal in the presence of Fe 0 mostly occurs within an in situ generated oxide film on Fe 0.

Highlights

This letter challenges the concept that Fe0/Me 0 bimetallic systems enhance contaminant reduction on Me0 surfaces
A metallic surface can be involved in chemical reactions in various ways: a metallic material can serve as a redox agent or catalyst, facilitating a reaction, or it can release metal species into the system [1,2]
Elemental iron (Fe0) and Fe0/Me 0 bimetallic systems used in water remediation (Fe0-H2O systems) are typical systems were all these three reaction paths might be involved: (i) Fe0 might serve as reducing agent, (ii) Fe0 surface might serve a catalyst for instance for the reduction through molecular (H2) or atomic hydrogen (H)

Summary

Introduction

This letter challenges the concept that Fe0/Me 0 bimetallic systems enhance contaminant reduction on Me0 surfaces. Elemental iron (Fe0) and Fe0/Me 0 bimetallic systems used in water remediation (Fe0-H2O systems) are typical systems were all these three reaction paths might be involved: (i) Fe0 might serve as reducing agent (direct reduction), (ii) Fe0 surface might serve a catalyst for instance for the reduction through molecular (H2) or atomic hydrogen (H) These factors include (i) the presence of molecular oxygen [3], (ii) the addition of a second more electropositive metal (e.g. Ag0, Co 0, Cu0, Ni 0, Pd 0, Pt 0, Ru0) yielding bimetallic systems [4,5], and (iii) increasing the surface area of iron by reducing its particle size [4].

Results

Conclusion