Transport of poly(acrylic acid) coated 2-line ferrihydrite nanoparticles in saturated aquifer sediments for environmental remediation
- 252 Downloads
Groundwater remediation using iron oxide and zero-valent iron nanoparticles (NPs) can be effective, but is limited in many applications due to the NP strong retention in groundwater-saturated porous media after injection, the passivation of the porous surface, and the high cost of nanomaterials versus macro scale iron. In this study, we investigated transport of bare and polymer-coated 2-line ferrihydrite NPs (30–300 nm) in saturated aquifer sediments. The influence of poly(acrylic acid) (PAA) polymer coatings was studied on the colloidal stability and transport in sediments packed column tests simulating groundwater flow in saturated sediments. In addition, the influence of calcium cations was investigated by transport measurements using sediments with calcium concentrations in the aqueous phase ranging from 0.5 (typical for most sediments) to 2 mM. Measurements were also made of zeta potential, hydrodynamic diameter, polymer adsorption and desorption properties, and bio-availability of PAA-coated NPs. We found that NP transport through the saturated aquifer sediments was improved by PAA coating and that the transport properties could be tuned by adjusting the polymer concentration. We further discovered that PAA coatings enhanced NP transport, compared to bare NPs, in all calcium-containing experiments tested, however, the presence of calcium always exhibited a negative effect on NP transport. In tests of bioavailability, the iron reduction rate of the coated and bare NPs by Geobacter sulfurreducens was the same, which shows that the PAA coating does not significantly reduce NP Fe(III) bioavailability. Our results demonstrate that much improved transport of iron oxide NP can be achieved in saturated aquifer sediments by introducing negatively charged polyelectrolytes and optimizing polymer concentrations, and furthermore, these coated NPs retain their bioavailability that is needed for applications in bio-environmental remediation.
KeywordsTransport Iron oxide nanoparticles Poly(acrylic acid) Groundwater remediation Bio-availability Iron reduction Environment
- Anderson RT, Vrionis HA, Ortiz-Bernad I, Resch CT, Long PE, Dayvault R, Karp K, Marutzky S, Metzler DR, Peacock A, White DC, Lowe M, Lovley DR (2003) Stimulating the in situ activity of Geobacter species to remove uranium from the groundwater of a uranium-contaminated aquifer. Appl Environ Microbiol 69:5884–5891CrossRefGoogle Scholar
- Hunter RJ (1988) Zeta potential in colloid science: principles and applications. Academic Press, New YorkGoogle Scholar
- Moon HS, McGuiness L, Kukkadapu RK, Peacock AD, Komlos J, Kerkhof LJ, Long PE, Jaffé PR (2010) Microbial reduction of uranium under iron- and sulfate-reducing conditions: effect of amended goethite on microbial community composition and dynamics. Water Res 44:4015–4028. doi:10.1016/j.watres.2010.05.003 CrossRefGoogle Scholar
- Tan KH (2011) Principles of soil chemistry. Taylor and Financial Group CRC Press, Boca RatonGoogle Scholar