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Characterization of humic substances: implications for trihalomethane formation
Ceyda Senem Uyguner1, Christine Hellriegel, William Otto
1Institute of Environmental Sciences, Bogazici University, Bebek, 34342 Istanbul, Turkey.
Analytical and Bioanalytical Chemistry
|June 25, 2004
Summary
Humic substances can form carcinogenic trihalomethanes (THMs) during water chlorination. While methods did not correlate with THM formation potential, NMR revealed functional group abundance and suggested reactive protons are in larger fulvic acid fractions.
Area of Science:
- Environmental Chemistry
- Water Treatment Science
- Analytical Chemistry
Background:
- Humic substances in water are precursors to carcinogenic trihalomethanes (THMs).
- THMs form during water disinfection via chlorination.
- Understanding the link between humic substance properties and THM formation potential (THMFP) is crucial for water safety.
Purpose of the Study:
- To investigate the relationship between physicochemical properties of humic substances and their trihalomethane formation potential (THMFP).
- To evaluate the utility of spectroscopic and NMR methods in characterizing humic substances relevant to THMFP.
Main Methods:
- UV-visible absorbance and fluorescence spectroscopy were employed.
- Nuclear Magnetic Resonance (NMR) spectra, including Gradient Modified Spin-Echo (GOSE) experiments, were analyzed.
- Diffusion coefficients were measured using BPPLED and GOSE-edited pulse sequences.
Main Results:
- No tested method directly correlated with THMFP.
- GOSE NMR intensities indicated the abundance of functional groups from lignin oxidation.
- GOSE-edited diffusion data suggested isolated protons, reactive to chlorination, are in larger molecular weight fulvic acid fractions.
Conclusions:
- Physicochemical characterization of humic substances using these methods did not predict THMFP.
- NMR and diffusion measurements provide insights into the structural characteristics of humic substances, particularly concerning reactive sites for chlorination.