Chemical oxidation may modify the hydrophobicity of dissolved organic matter (DOM), such as humic substances, proteins, polysaccharides, and lipids, affecting their fate in water treatment processes, including sorption to activated carbon and membranes (e.g., organic fouling). Similar reactions with hypochlorous and hypobromous acids produced at inflammatory sites affects the fate of biomolecules (e.g., protein aggregation) in the human body. In this study, quartz crystal microbalance with dissipation monitoring (QCM-D) was used to evaluate changes in the non-covalent interactions of proteins, polysaccharides, fatty acids, and humic and fulvic acids with a C18 alkanethiol-coated hydrophobic surface as a function of increasing doses of chlorine (HOCl), bromine (HOBr), and ozone (O3). All three oxidants, particularly O3, increased the hydrophobicity of proteins at low doses, likely by promoting the exposure of the hydrophobic cores of proteins via unfolding. At higher oxidant doses, however, the hydrophobicity of proteins declined below levels observed in the unoxidized proteins. All three oxidants reduced the hydrophobicity of polysaccharides and fatty acids. HOCl and HOBr increased the hydrophobicity of humic and fulvic acids with maxima at moderate doses, while O3 decreased hydrophobicity. The behavior observed with two water samples was similar to that observed with humic and fulvic acids, pointing to the dominance of these constituents. For chlorination, the maximum hydrophobicity was observed within the range of doses typically applied during water treatment. Our results suggest that ozone pretreatment would minimize membrane fouling, while chlorine pretreatment would facilitate DOM removal by activated carbon.

Impact of chemical oxidation on the hydrophobicity of dissolved organic matter

248th National Meeting (2014)

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