Zero-valent iron particles

Liang F, Fan J, Guo Y, Fan M, Wang J, Yang H (2008) Reduction of nitrite by ultrasound-dispersed nanoscale zero-valent iron particles. Ind Eng Chem Res 47(22) 8550-8554... 

Attention has been particularly devoted to the application of nanoscale particles of zero-valent iron, and a range of halogenated aliphatic compounds has been examined. 

Lin, Y., Weng, C. and Chen, F. (2008) Effective removal of AB24 dye by nano/ micro-size zero-valent iron. Separation and Purification Technology, 64, 26-30. Wang, C.B. and Zhang, W.X. (1997) Synthesizing nanoscale iron particles for rapid and complete dechlorination of TCE and PCBs. Environmental Science and Technology, 31, 2154-2156. 

DECHLORINATION OF CHLORINATED HYDROCARBONS BY ZERO-VALENT IRON NANO-PARTICLES... 

Zhang and Wang (1997) studied the reaction of zero-valent iron powder and palladium-coated iron particles with trichloroethylene and PCBs. In the batch scale experiments, 50 pL of 200 pg/mL PCB-1254 in methanol was mixed with 1 ml ethanol/water solution (volume ratio = 1/9) and 0.1 g of wet iron or palladium/iron powder in a 2-mL vial. The vial was placed on a rotary shaker (30 rpm) at room temperature for 17 h. Trichloroethylene was completely dechlorinated by the nanoscale palladium/iron powders within the 17-h time period. Only partial dechlorination of PCB-1254 was observed when wet iron powder was used. 

The polymer/metal particle composites have been synthesized by utilizing fine metal surfaces as effective initiation sites for radical polymerization of vaporized vinyl monomers. On the metal surfaces, GASP of vinyl monomers is initiated and induces the formation of polymer thin-film coatings of the fine metal particles. Andou et al. demonstrated that GASP of MMA on a zero-valent iron (Fe(0))... 

Reductive dechlorination of HCB can be achieved with the combination of electrokinetics with the appropriate catalysts such as nanoscale zero valent iron (NZVl). The electric field can be used as a mechanism for the delivery of NZVl into the soil [10]. Reductive dechlorination can be achieved in the soil or even upon the cathode if the contaminant reaches the cathode compartment. Other metallic catalysts such as Cu/Fe or Pd/Fe bimetal microscale particles were satisfactorily used with the same purpose. Dechlorination of hexachlorobenzene up to 98 % was achieved with Cu/Fe [27] and only 60 % with Pd/Fe [20]. 

Spectra from surfaces prepared under dry reduction conditions are dominated by the peak for elemental iron. They all, however, showed a shoulder at 710 eV, characteristic of the presence of unreduced material in, presumably, both ferrous and ferric oxidation states. The position and linewidth of the zero-valent iron peak are different from those of iron foil. A shift of 0.2-0.3 eV to higher binding energy was typical as well as a broader linewidth (2.2 eV for ion foil and ca 3.0 eV for the catalyst). There was no detectable relaxation shift in the iron spectrum. Therefore, the possibility of small-particle effects seems unlikely. The presence of large concentrations of local defects, in addition to possible spectroscopic effects of local variations in the position of the Fermi level, offer plausible explanations for the differences in spectral parameters. 

If dried the particles become too reactive to use in groundwater remediation All of the above What is the advantage of using nanoscale iron in comparison to commercially available powdered zero-valent iron ... 

Another means to promote in situ abiotic transformation is the construction of a reactive wall, physically similar to a slurry wall but with a porous backfill, containing chemical reactants, through which contaminated groundwater can flow. One such reactant, often referred to as zero-valent iron, is made up of fine particles of elemental (metallic) iron. Reactions between elemental iron and some dissolved chlorinated solvents, for example, can result in dechlorination of the solvents to species that are more susceptible to subsequent biodegradation. 

Module 2 Using nanoscale bimetallic iron particles for groundwater remediation. This module has been created according to existing literature. Trichloroethylene (TCE), one of the most ubiquitous soil and groundwater contaminants, is used as a sample contaminant. The reductive dehalogenation of TCE via zero-valent nano iron particles can be described by the following equation (29) ... 

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