Fate, reactivity and environmental impact of using iron nanoparticles for site clean-up

Targeted under NERC's Water theme, the proposed project is aimed at determining the fate, reactivity and environmental risk of deploying nanoscale iron particles (INP) for the cleanup of polluted sites and groundwaters around the UK. The project is CASE supported by URS/Scott Wilson with advisory input from DEFRA (Dr Helinor Johnston) and CL:AIRE (Dr John Henstock). The Problem: The increased development and use of engineered nanomaterials has the potential to offer great benefits to society through their exploitation within numerous products developed by diverse industries. Some applications of nanomaterials have the potential to afford environmental benefits and of particular interest is the use of nanoscale particles of zerovalent iron (INPs) for the in situ cleanup of contaminated land and groundwater. Theoretical and practical evidence suggests that these INPs can be used to rapidly remediate contaminated sites at a significantly reduced cost relative to conventional methods. Most significantly they are also applicable for a wide range of hazardous chemicals, including polychlorinated biphenyls (PCBs); heavy metals and even radionuclides. To date the UK government has adopted a precautionary approach to the deliberate release of nanomaterials into the environment and consequently the use of INP remediation technology is not currently permitted by the UK Environment Agency. In July 2010 DEFRA commissioned a study (CB0440) to evaluate whether the hypothesised or known detrimental effects associated with the intentional release of INPs into the environment, outweigh the benefits that may be realised by using INP for site cleanup. Whilst this study has not yet been completed, a recent detailed review provided by the Bristol group has highlighted that much is still unknown about the true geochemical fate of INP injected into the subsurface, their true efficiency for cleanup of pollutants and the level of impact they may have on the environment. The Solution: By partnering academia with industry, the current project proposes to bridge the gaps in our current understanding and provide valuable site-derived data relating to the lifecycle of INPs in the environment. The project will build upon existing links between the Bristol Interface Analysis Centre (IAC), a group with the strongest UK track record for INPs research, and URS/Scott Wilson, an internationally renowned geotechnical and geoenvironmental engineering consultancy. Over the period of the project, the student will perform both laboratory and field-based investigations using INP of different sizes and types (wet-formed, dry-formed, annealed, surfactant coated) to evaluate their relative performance for contaminant remediation in natural waters of complex geochemistry. The project will also seek to better understand specific fundamental lifecycle aspects of INP injected into pore-water systems, specifically the factors that control transport, transformation, contaminant-INP reactivity and microbial impact. Of specific value to the project, URS/Scott Wilson will provide access to contaminated sites within the UK and/or overseas where the student, under supervision of the CASE supervisor, will participate in the planning, deployment and monitoring of a remediation project using INP. In the UK the student will also have access to a specialist 50m3 hydrogeochemical test cell located at URS/Scott Wilson's laboratories in Nottingham, where groundwater remediation systems using INP's will be prototyped and optimised. It is considered that the current studentship, which will be advised by both DEFRA and CL:AIRE, will produce data and practical knowledge that will help to shape future UK legislation and industry best practice for the use of INP in site clean-up.