Kinectics and pathways of degradation of disinfection by-products by synthetic iron oxide minerals

Reduction of disinfection by-products (DBP) by iron oxides may play a role in the degradation of DBP in water distribution systems. The kinetics and pathways of the reactions of six selected DBP, i.e., dichloromethane (TCM), trichloroacetic acid, 1,1,-trichloropropanone (1,1,1-TCP), dichloroactaldehyde, trichloroacetonitrile (TCAN), and trichloronitromethane (TCNM), with synthetic iron oxides were determined. Hydrogenolysis and hydrolysis were the dominant reaction pathways for most DBP. The degradation rate of TCNM by Fe(II)/goethite was much faster than that of TCAN. No reduction of 1,1,1-TCP occurred in the presence of Fe(II)/goethite. The observed loss of 1,1,1-TCP was due to both hydrolysis and sorption. 1,1,1-TCP was hydrolyzed to TCM, which was the only product detected. Also, 1,1,1-TCP absorbed to the goethite surface. Thus, sorption may be an important loss mechanism for some DBP in water distribution systems. This is an abstract of a paper presented at the 228th ACS National Meeting (Philadelphia, PA 8/22-26/2004).