Oxidative coupling reactions mediated by horseradish peroxidase in solutions containing natural organic matter (NOM) comprised by model fulvic acids were performed in completely mixed batch and flow reactors. The subsequent removal of NOM by ultrafiltration was found to be significantly enhanced for solutions subjected to oxidative coupling. Spectroscopic examinations revealed that the fulvic acid molecules were effectively reconfigured by substantial conversion of aromatic hydroxyl groups into ether bonds via oxidative coupling. These conversions apparently result in cross-linking of NOM moieties to form stable species of greater molecular size, thus rendering them more readily removable by ultrafiltration. The results of this study suggest that catalyzed oxidative coupling reactions in combination with ultrafiltration can be developed into an effective scheme for NOM removal in water treatment operations.
- oxidative coupling
- © 2004 IWA Publishing and the authors