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

摘要

This study was to explore the formation of iodinated disinfection by-products (I-DBPs), including iodoform (CHI_3), iodoacetic acid (IAA) and triiodoacetic acid (TIAA), when iodide-containing artificial synthesized waters and raw waters are in contact with chlorine dioxide (C1O_2). Among the investigated I-DBPs, CHI_3 was the major species during C1O_2 oxidation in artificial synthesized waters. Impact factors were evaluated, including the concentrations of C1O_2, iodide (I~), dissolved organic carbon (DOC) and pH. Formation of CHI_3, IAA and TIAA followed an increasing and then decreasing pattern with increased C1O_2 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 nM. When 100 μg/L Pand C1O_2 (7.5-44.4 μM) were spiked to the raw water samples from Yangshupu and Minhang drinking water treatment plant, certain amounts of CHI_3 and IAA were found under pH 7 and the concentrations were strongly correlated with C1O_2 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 C1O_2 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.