AbstractsChemistry

A SERS-based investigation of the molecular interaction between natural organic matter and colloidal silver nanoparticles in porous media

by Jessica L. Fraley




Institution: Wright State University
Department: Chemistry
Degree: MS
Year: 2014
Keywords: Chemistry; chemistry
Record ID: 2029681
Full text PDF: http://rave.ohiolink.edu/etdc/view?acc_num=wright1409694849


Abstract

The significant presence of silver nanoparticles (AgNPs) in numerous consumer products and various applications of today’s society raises major concerns with respect to their release into the environment. Because groundwater represents an important transport pathway from contamination sources to human and environmental receptors, it is critical to understand how natural organic matter (NOM), a main component of groundwater, interacts with colloidal AgNPs and influences their stability and mobility. Thus, this study uses Raman and surface-enhanced Raman spectroscopy (SERS) to examine the possible molecular interactions between widely-used Creighton AgNPs (11 mg L-1) and NOM (0-160.0 mg L-1 of humic and fulvic acids) in porous media (glass b>eads) and at various benchmark incubation times (0, 1 hr, 3 hrs, 1 day, 1 week, and 60 days). Additionally, fluorescence spectroscopy was employed to quantify the amount of NOM adsorbed onto AgNPs. It was found that NOM forms surface-complexed species with AgNPs mainly through the ionized carboxylic moieties located in the immediate vicinity of the metallic nanosurface, and the interaction becomes stronger with the increase in incubation time. The fluorescence emission spectra confirmed the Raman/SERS observations of significant fluorescence quenching upon the AgNP addition and the formation of AgNP-NOM-AgNP aggregates, which may decrease AgNP mobility during their groundwater transport.