Removal of low-molecular weight DBPs and inorganic ions for characterization of high-molecular weight DBPs in drinking water

High-molecular weight (MW) halogenated disinfection byproducts (DBPs) may cause adverse health effects. In this work several issues related to the better separation and characterization of the high MW halogenated DBPs (MW>500 Da) were studied. Ultrafiltration (UF) coupled with a nominal 500-Da membrane was employed to flush out low MW DBPs and inorganic ions. Two procedures, intermittent UF and continuous UF, were used and compared. The results demonstrate that haloacetic acids, chloride and sodium ions could be effectively flushed out, and most of phosphate ions could be flushed out for a given dilution number or sufficient Milli-Q water. The size exclusion chromatograms indicate that haloacetic acids and trihalomethanes were not bound to Suwannee River fulvic acid (SRFA); 2,4,6-trichlorophenol might form some binding with SRFA, but it appeared to be very weak and readily broken up when passing along the size exclusion column. The octanol–water partition coefficients of low MW DBPs and the properties of humic substances seem to play key roles in determining the formation of possible bindings between low MW DBPs and humic substances.