Characterization of Nanoparticles and Colloids in Aquatic Systems 1. Small Angle Neutron Scattering Investigations of Suwannee River Fulvic Acid Aggregates in Aqueous Solutions
Abstract
Fulvic acids (FA) and humic acids (HA) constitute 30–50% of dissolved organic matter in natural aquatic systems. In aqueous solutions, a commonly accepted view is that FA and HA exist as soluble macroligands at low concentration and as supramolecular aggregates at higher concentration. The size, shape and structure of these aggregates are still the subject of ongoing debate in the environmental chemistry literature. In this article, we use small angle neutron scattering (SANS) to assess the effects of solute concentration, solution pH and background electrolyte (NaCl) concentration on the structures of Suwannee River FA (SRFA) aggregates in D₂O. The qualitative features of the SANS curves and data analysis are not consistent with the view point that SRFA forms micelle-like aggregates as its concentration in aqueous solution increases. We find that SRFA forms fractal aggregates in D₂0 with size greater than 242 nm. The SRFA aggregates undergo a significant degree of restructuring in compactness as solution pH, solute concentration and NaCl concentration increase.
Additional Information
© 2005 Springer. Received 9 March 2005; accepted in revised form 17 May 2005. We thank Dr. Steve Kline of the NIST Center for Neutron Research for serving as NIST internal reviewer for this manuscript. This research was carried out in the Department of Civil Engineering at Howard University, at the Materials and Process Simulation Center of the Beckman Institute at the California Institute of Technology and at the Center for Neutron Research of the National Institute of Standards and Technology (NIST). Funding for this research was provided by the US Department of Commerce to Howard University and Caltech by the US Department of Commerce under Cooperative Agreement 7NANB8HO102. Partial funding for this research was also provided to Howard University by the Great Lakes and Mid- Atlantic Hazardous Substance Research Center under Grant R-825540 from the USEPA Office of Research and Development. We acknowledge the support of NIST in providing facilities used for this work. This material is based upon activities supported by the National Science Foundation under agreement No. DMR-9986442.Additional details
- Eprint ID
- 101475
- Resolver ID
- CaltechAUTHORS:20200221-154418772
- 7NANB8HO102
- Department of Commerce
- R-825540
- Environmental Protection Agency (EPA)
- National Institute of Standards and Technology (NIST)
- DMR-9986442
- NSF
- Created
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2020-02-24Created from EPrint's datestamp field
- Updated
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2021-11-16Created from EPrint's last_modified field
- Other Numbering System Name
- WAG
- Other Numbering System Identifier
- 0629