Preoxidation of Two Nitrosamines Precursors and It’s Effects on N-Nitrosodimethylamine Formation in Water
Date Issued
2010
Date
2010
Author(s)
Lo, Shih-Lin
Abstract
Recently, many studies focused on the residuals of pharmaceuticals and personal care products (PPCPs) in the water environment. PPCPs may harm the environment and public health when they are discharged into natural water with the domestic or industrial wastewater. In this study, two PPCP compounds were selected as representatives of the PPCPs and the precursors of disinfection byproducts (DBPs) in water treatment processes. The two PPCPs selected were 3-dimethylaminopropyl methacrylamide (DMAPMA) and diltiazem, where DMAPMA is used as stock for industrial and household products and diltiazem is widely used in medical prescription. Chlorine dioxide, hypochlorous acid, ozone, and monochloramine were used as the disinfectants in this study to compare their oxidizing abilities and to assess the dimethylamine (DMA), nitrosodimethylamine (NDMA) and other DBPs formation after contacted with the precursors.
The experimental result showed that DMA can be formed when the two precursors were treated with the disinfectants. Several factors include the concentrations of precursors, the doses of disinfectants and pH values in aqueous environment can influence the DMA formation. Besides, chlorine dioxide and ozone have higher reactivity to diltiazem, and hypochlorous acid has higher reactivity to DMAPMA. The mild oxidizing power of monochloramine produces no apparent difference on DMA formation for the two precursors.
Highest NDMA formation was obtained when chloramine was used as the disinfectant. The contact time of pre-oxidation and DMA formation during pre-oxidation can affect the final NDMA formation. Both THMs and HAAs can also be formed during chlorination, however, their concentration can be reduced when chlorine dioxide and ozone were used as the pre-oxidant. In addition, several other nitrosamines were formed when the precursors were treated with chlorine.
Subjects
DMA
NDMA
chlorine dioxide
hypochlorous acid
ozone
monochloramine
SDGs
Type
thesis
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