Paper No. 31-4
Presentation Time: 9:00 AM-5:30 PM
DEVELOPMENT OF IN-SITU REMEDIATION TECHNIQUE FOR POLYCYCLIC AROMATIC HYDROCARBONS IN SOILS: I. STABILITY OF FLUORESCENT-LABELLED SIO2 NANOPARTICLE-SUPPORTED LIPID BILAYER IN MICRO-MODELS
Polycyclic aromatic hydrocarbons (PAHs) are considered as priority pollutants by the EPA since they are widespread, serious risks for ecosystems and human health due to their carcinogenic and mutagenic effects. PAHs have low water solubility, and are strongly adsorbed onto environmental surfaces, accumulating in soils and sediments. Elevated levels of PAHs have been detected in urban (sub)surface soils throughout the US, in concentrations often several orders of magnitude greater than established EPA screening levels. We have previously shown that SiO2 nanoparticle-supported lipid bilayers (NP-SLB) formed by using inexpensive, environmentally-friendly geomaterials, such as SiO2 nanoparticles, as well as a natural organic matter component, lipids, can remove PAHs. Here, we aim to examine the stability and feasibility of the remediation method under various environmental conditions by tracing their migration in different environments. First, we successfully synthesized the composite material with approximately 200-nm SiO2 nanoparticles, fluorescently-labelled with Alexa Fluor 350 NHS Ester dye and lipids tagged with a DiA styryl dye, which allowed us to trace them separately for testing the stability and integrity of the composite material. Further, we fabricated optically transparent plates with 2-D channels that are composed of SiO2 and SiO2 surfaces functionalized with humic acid and/or clay minerals to closely simulate heterogeneity and complexity in soil matrices. Dynamic light scattering, transmission electron microscopy, spectrofluorometer, and nanodifferential scanning calorimetry were employed for the detailed material characterization and measurements. Results of this study indicated that SiO2 NP-SLB is a robust and stable composite material, desirable for in-situ remediation of PAHs in soils. Further, micro-model studies clearly presented advantages over batch sorption/desorption experiments or soil column experiments by visualizing both NPs and lipids differently in the presence of various environmental surfaces. Such successful delivery of the intact and stable composite material to the target contaminated sites expects to increase the efficiency of NP-SLB system for the PAHs removal in soils.