REMEDIATING CONTAMINATED AQUIFERS WITH MAGNETIC ENGINEERED NANOPARTICLES

Magnetic shell crosslinked knedel-like nanoparticles (MSCKs) were engineered to aid in the cleanup of oil spills. These engineered nanoparticles (ENP’s) are approximately 70 nm in diameter. MSCKs have a hydrophilic shell and hydrophobic core which encapsulates suspended iron oxide nanoparticles, rendering them magnetic. MSCKs operate like discrete surfactant packets: increasing the mobility and apparent solubility of hydrophobic species, but do so within the confines of discrete particles which can then be recovered by filtration or magnetic removal. MSCKs accomplish this via sequestration of hydrophobic species from through the hydrophilic shell and into the hydrophobic core where hydrocarbon contaminants are stabilized. In batch tests MSCKs sequestered crude oil ten times their mass (1000 mg of oil per 100 mg of MSCKs). The objective of this study is to quantify their transport and contaminant sequestration capabilities in saturated porous media as a first step towards their potential use in aquifers plagued with hydrophobic contaminants.

MSCK transport and reaction efficacy was determined with one dimensional impulse column experiments. MSCKs were readily transported in saturated sand, with an average recovery rate of 99%. In the presence of 10% clay particles, recovery was reduced to 68%. In the presence of xylene, MSCKs completely sequestered the aqueous phase pollutant (8.7 mg/L), although recovery of the MSCKs fell to 61% in sand and 53% in clay. The presence of a non-aqueous phase liquid (NAPL) (5% mineral oil by volume) further reduced MSCKs recovery in sand to 53%. The MSCKs recovered in the effluent had sequestered the mineral at ratios far below their capability demonstrated in batch experiments (3-10 mg of oil per 100 mg of MSCKs).

This study demonstrates that MSCKs show promising attributes for use in remediation. However, further manipulation of their chemical and morphological properties, and further testing of optimal groundwater flow rates and injected concentrations of the MSCK’s is needed to optimize their performance in situ.