Formation Of Iodinated Disinfection By-Products From Iodinated X-ray Contrast Media, Iopamidol, In The Presence Of Nom And Chlorinated Oxidants

The objective of this study was to investigate the formation of iodinated disinfection by-products (iodo-DBPs) where iodinated x-ray contrast media (ICM), Iopamidol, acted as source of iodine, with respect to pH (6.5, 7.5, 8.5 and 9.0) in the presence of natural organic matter (NOM) and chlorinated oxidant.This was achieved by varying the NOM concentration as well as iopamidol concentrations.Iodinated trihalomethane (iodo-THM) formation was highest at pH 9.0 for chlorine and at pH 6.5 for monochloramine.A considerable increase in formation was observed from pH 6.5 to 7.5 and from 8.5 to 9.0 with respect to chlorine as oxidant.Monochloramine expressed a decreasing trend from pH 6.5 to 9.0.The most predominately formed iodo-THM was dichloroiodomethane, 57.5 nM for chlorine at pH 9.0 (DOC = 2.51 mg/L-L) and 35.2 nM for monochloramine at pH 6.5 (DOC = 2.51 mg/L-L).Chloroform formation was also impacted by the introduction of iopamidol to reactor.Monochloramine produced a wider variety of iodo-DBPs at lower concentrations in comparison to chlorine.Variation of NOM proved to impact the formation of iodo-DBPs.When NOM levels were reduced to a quarter of the original capacity (2.51 -0.63 mg/L-L) dichloroiodomethane formation doubled at pH 9.0 with respect to chlorine (110.5 nM).Monochloramine expressed a decreasing trend with respect to decreasing levels of NOM with the source water.For both oxidants, half and quarter capacity of NOM, 1.26 and 0.63 mg/L-L respectively, expressed considerably similar formation.iii