Ranitidine, a histamine H2-receptor antagonist, has been detected in wastewater effluents or surface waters of industrialized countries at concentrations of sub mg/L ranges. As ranitidine can produce NDMA (N-nitrosodimethylamine), a probable human carcinogen, with >60% yields upon chloramination, its presence in water resources has raised a concern for water utilities using chloramine. This study investigated transformation kinetics of ranitidine and changes of its NDMA formation potential during oxidative water treatments with chlorine, ozone, UV (254 nm), and UV/H2O2, which is currently poorly understood. Transformation of ranitidine was rapid ( 106 M-1 s-1). In addition, the ranitidine transformation by ozone resulted in near 1:1 stoichiometric reduction of NDMA formation potential at pH=8, which could be explained by the fast reaction of ozone with the tertiary amine moiety. Ranitidine was transformed under UV irradiation with fluence-based first-order rate constants of ~1.5�10-3 cm2 J-1. However, the acetamidine-moiety was mainly responsible for the photo-liability of ranitidine, therefore, the NDMA formation potential decreased only marginally (<30%) at the UV dose of up to 1500 mJ/cm2. Rates of the ranitidine transformation and the reduction of the NDMA formation potential significantly increased upon the addition of H2O2 during UV irradiation, which could be attributed to the reaction of OH radicals with the furan-moiety. Overall, this study demonstrates pre-oxidations with chlorine, ozone, or OH radicals efficient options to eliminate the NDMA formation potential of ranitidine.

Transformation of ranitidine during water treatments with chlorine, ozone, UV, and UV/H<sub>2</sub>O<sub>2</sub>: Kinetics and effects on NDMA formation potential

248th National Meeting (2014)

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Transformation of ranitidine during water treatments with chlorine, ozone, UV, and UV/H2O2: Kinetics and effects on NDMA formation potential

Transformation of ranitidine during water treatments with chlorine, ozone, UV, and UV/H₂O₂: Kinetics and effects on NDMA formation potential