Fate and Transport of Polymeric Nanoparticles in Saturated Porous Media
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The application of engineered nanomaterials has improved many traditional groundwater remediation technologies; however, the development of novel nano-scale remediation technologies remains limited. magnetic shell crosslinked knedel-like (MSCKs) are novel polymeric nanoparticles whose application towards groundwater remediation is promising. MSCKs differ from traditional remediation technologies in that they are non-reactive and highly selective for specific contaminants. MSCKs are spherical particles with a hydrophilic shell and hydrophobic core which entraps suspended iron oxide nanoparticles, rendering MSCKs magnetic. MSCKs operate like discrete surfactant packets: increasing the mobility and apparent solubility of hydrophobic species, but doing so within the confines of discrete particles which can then be recovered by filtration or magnetic removal. MSCKs accomplish this via the sequestration of hydrophobic species through the shell and into the core where the hydrophilic environment is able to entropically stabilize the contaminant. In aqueous phase benchtop tests, MSCKs have been shown to sequester ten times their mass of crude oil. This study explores the transport characteristics and contaminant sequestration capabilities of MSCKs in saturated porous media. Transport characteristics were determined via one dimensional impulse column experiments in columns containing a saturated sand or a saturated sand/clay mixture. Sequestration experiments were determined under identical conditions, with aqueous phase contaminant sequestration being done in ambient 8.66 mg/L m-xylene (aq) and free phase contaminant sequestration being conducted in a column with roughly 5% of the pore space occupied by free phase mineral oil. The results of these column studies indicated that MSCKs readily transport through saturated sand with virtually no loss in recovery but that in the presence of clays, MSCK transport is retarded via irreversible attachment and/or aggregation and straining of MSCKs. The presence of hydrocarbons in either the aqueous phase or free phase also reduces the mobility of MSCKs and lowers recovery. Additionally, this study has revealed that MSCKs can remove m-xylene (aq) to below the detection limit and well below the regulatory limits for residential groundwater. The sequestration of free phase mineral oil by MSCKs was significantly lower, with mineral oil recovery totaling between 3% and 10% of the total mass of MSCKs injected.
Sanders, Jonathan Edward (2015). Fate and Transport of Polymeric Nanoparticles in Saturated Porous Media. Master's thesis, Texas A & M University. Available electronically from