Date of this Version
U.S. Government Work
Natural organic matter (NOM) affects the stability and transport of nanoparticles (NPs) in natural waters by modifying their physiochemical properties. Source location, and seasonal variations, influence their molecular, physical and electrical charge properties. To understand the variations of NOM on the mobilization of NPs, large volumes of water were collected fromthe Ohio River (OR) over winter and summer seasons and dissolved NOMs were concentrated. The chemical and structural differences of these NOMs were compared with the Suwannee River humic acid (SRHA) SRHA using 1H and 13C nuclear magnetic resonance spectroscopy, and Fourier transforms infrared (FTIR) spectroscopy. Thermal analysis and FTIR confirmed that differences in composition, structure, and functional groups are a result of SRHA fractionation compared to wholemolecule OR-NOM. The influence of OR-NOMs on the surface charge of CeO2NPs and the effects on the transport and retention in a three-phase (deposition-rinse-re-entrainment) sand-packed columns were investigated at CeO2 NPs initial concertation of 10 ppm, pH 6.8, increasing ionic strength (3, 5, and 10 mM), retention time of 1 min, and increasing NOM concentration (1, 5, and 10 ppm). The summer OR-NOM showed higher stabilization and mobilization effect on the CeO2 than the winter NOM; while their effect was very different form the SRHA. The stabilization of NPs is attributed to both electrostatic and steric effects. The differences in the chemical structure of the complex and heterogeneous NOMs showed disparate reactivity and direct impact on CeO2-NPs stability. Using SRHA to study the effect of NOMfor drinkingwater related assessment does not sufficiently represent the natural conditions of the environment.