Formation of iodinated disinfection by-products during oxidation of iodide-containing waters with chlorine dioxide

• I-DBPs can be produced when iodide-containing waters are in contact with chlorine dioxide.
• Maximum concentration of I-DBPs was generated at pH 8.
• ClO2, I– and NOM concentrations showed significant effects on the formation of I-DBPs.
• Carboxylic acids, phenols and amino acids could form a considerable amount of I-DBPs.

This study was to explore the formation of iodinated disinfection by-products (I-DBPs), including iodoform (CHI3), iodoacetic acid (IAA) and triiodoacetic acid (TIAA), when iodide-containing artificial synthesized waters and raw waters are in contact with chlorine dioxide (ClO2). Among the investigated I-DBPs, CHI3 was the major species during ClO2 oxidation in artificial synthesized waters. Impact factors were evaluated, including the concentrations of ClO2, iodide (I–), dissolved organic carbon (DOC) and pH. Formation of CHI3, IAA and TIAA followed an increasing and then decreasing pattern with increased ClO2 or DOC concentration. I-DBPs yield was significantly affected by solution pH. High concentrations of I-DBPs were generated under circumneutral conditions with the maximum formation at pH 8. The increase of I– concentration can increase I-DBPs yields, but the increment was suppressed when I– concentration was higher than 50 μM. When 100 μg/L I–and ClO2 (7.5–44.4 μM) were spiked to the raw water samples from Yangshupu and Minhang drinking water treatment plant, certain amounts of CHI3 and IAA were found under pH 7 and the concentrations were strongly correlated with ClO2 dosage and water qualities, however, no TIAA was detected. Finally, we investigated I-DBPs formation of 18 model compounds, including 4 carboxylic acids, 5 phenols and 8 amino acids, treating with ClO2 when I– was present. Results showed that most of these model compounds could form a considerable amount of I-DBPs, especially for propanoic acid, butanoic acid, resorcinol, hydroquinone, alanine, glutamic acid, phenylalanine and serine.

Figure optionsDownload high-quality image (72 K)Download as PowerPoint slide