Doctoral Student's Poster Recognized

Nano-scale Zero-Valent Iron: an Effective Mitigant that also Pollutes
The persistence of nano-scale iron particles raises environmental questions

Adeyemi Adeleye

Second-year doctoral student Adeyemi "Yemi" Adeleye and his co-authors received a certificate of merit from the Division of Environmental Chemistry of the American Chemical Society (ACS) for his poster presentation at the recent ACS meeting in Philadelphia.

The certificate recognizes ACS members who are making their first presentation at a national meeting of the Environmental Chemistry Division. Yemi's presentation was "judged to be of high quality [in forwarding] the efforts of the Enviromental Chemistry Divistion to better understand and protect the environment."

Adeleye's poster summarized a paper co-authored by Bren professors Arturo Keller and Hunter Lenihan and researcher Robert Miller describing a project related to the increasing use of nanoscale zero-valant iron (nZVI) in remediating a wide rage of environmental pollutants.

According to the abstract, "Bench and field pilot studies have recorded successful cleanup of many pollutants using nZVI and other iron-mediated nanoparticles. However, a major question remains unanswered: what is the long-term environmental fate of the iron nanoparticles used for remediation?"

To find out, the researchers aged three types of commercial nZVI in various aqueous media, including a groundwater sample, under aerobic and anaerobic conditions for 28 days, and found that the bulk of the nZVI injected into polluted sites will end up in the sediment phase of the aquifer.

"The study demonstrated that injection of nZVI into the ground for remediation purposes should be preceded by proper evaluation of the specific site in order to be able to project the possible changes the nZVI may cause and how it might influence the ecosystem," says Adeleye.

The implications of the persistence of nZVI in the subsurface, mainly as iron oxides include:

  • Organisms in the subsurface and aquatic systems around injection wells may be exposed to potentially toxic levels of iron species, as has been demonstrated by another study carried out in the same lab.
  • High levels of iron particulates could affect groundwater transport by reducing aquifer porosity and permeability.
  • Possible contamination of groundwater with high levels of iron.
  • The potential of elemental iron to change water chemistry drastically, which may in turn affect the ecosystem supported by the water.

Adeleye's goal as a doctoral student is to better understand the fate and transport of nanoparticles in the environment. A scientific paper based on this experiment has been written and is currently under review.