The role of reactive chlorine and nitrogen species in micropollutant degradation in UV/monochloramine AOP

Monochloramine (NH2Cl) is applied upstream of reverse osmosis (RO) membranes for biofouling control. Residual NH2Cl can undergo UV photolysis downstream, generating reactive species for an AOP to occur. NH2Cl is typically generated from combining sodium hypochlorite and ammonium chloride or sulfate....

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Main Author: Seah, Zi Quan
Other Authors: Shane Allen Snyder
Format: Thesis-Master by Research
Language:English
Published: Nanyang Technological University 2024
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Online Access:https://hdl.handle.net/10356/173492
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spelling sg-ntu-dr.10356-1734922024-03-07T08:52:06Z The role of reactive chlorine and nitrogen species in micropollutant degradation in UV/monochloramine AOP Seah, Zi Quan Shane Allen Snyder School of Civil and Environmental Engineering Nanyang Environment and Water Research Institute ssnyder@ntu.edu.sg Engineering Monochloramine (NH2Cl) is applied upstream of reverse osmosis (RO) membranes for biofouling control. Residual NH2Cl can undergo UV photolysis downstream, generating reactive species for an AOP to occur. NH2Cl is typically generated from combining sodium hypochlorite and ammonium chloride or sulfate. This study investigated the degradation of four compounds of interest – acetaminophen, caffeine, sucralose and 1,4-dioxane – in UV/NH2Cl at the bench scale to study their reactivity with reactive chlorine (RCS) and nitrogen species (RNS). With methanol acting as a scavenger of •OH radicals, the performance of UV/NH2Cl was compared to UV/H2O2 and UV/HOCl. When ammonium sulfate was used as the ammonia source over ammonium chloride, the overall degradation of micropollutants was higher and caffeine was exclusively degraded. The higher concentration of chloride ions, contributed by ammonium chloride for monochloramine formation, significantly influenced the speciation of radicals generated that impacted micropollutant degradation. This suggests that the reactivity of more selective RCS (Cl2•−, •ClO, ClOH•−) and RNS (•NH2, •NO, •NO2, etc.) varies with micropollutants of interest. In presence of higher chloride concentration from the ammonia source, RCS generated •OH radicals and consumed by RNS to form NO3−, showing the impact of the ammonia source and water matrix on UV/NH2Cl performance. Master's degree 2024-02-07T05:24:32Z 2024-02-07T05:24:32Z 2023 Thesis-Master by Research Seah, Z. Q. (2023). The role of reactive chlorine and nitrogen species in micropollutant degradation in UV/monochloramine AOP. Master's thesis, Nanyang Technological University, Singapore. https://hdl.handle.net/10356/173492 https://hdl.handle.net/10356/173492 10.32657/10356/173492 en This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License (CC BY-NC 4.0). application/pdf Nanyang Technological University
institution Nanyang Technological University
building NTU Library
continent Asia
country Singapore
Singapore
content_provider NTU Library
collection DR-NTU
language English
topic Engineering
spellingShingle Engineering
Seah, Zi Quan
The role of reactive chlorine and nitrogen species in micropollutant degradation in UV/monochloramine AOP
description Monochloramine (NH2Cl) is applied upstream of reverse osmosis (RO) membranes for biofouling control. Residual NH2Cl can undergo UV photolysis downstream, generating reactive species for an AOP to occur. NH2Cl is typically generated from combining sodium hypochlorite and ammonium chloride or sulfate. This study investigated the degradation of four compounds of interest – acetaminophen, caffeine, sucralose and 1,4-dioxane – in UV/NH2Cl at the bench scale to study their reactivity with reactive chlorine (RCS) and nitrogen species (RNS). With methanol acting as a scavenger of •OH radicals, the performance of UV/NH2Cl was compared to UV/H2O2 and UV/HOCl. When ammonium sulfate was used as the ammonia source over ammonium chloride, the overall degradation of micropollutants was higher and caffeine was exclusively degraded. The higher concentration of chloride ions, contributed by ammonium chloride for monochloramine formation, significantly influenced the speciation of radicals generated that impacted micropollutant degradation. This suggests that the reactivity of more selective RCS (Cl2•−, •ClO, ClOH•−) and RNS (•NH2, •NO, •NO2, etc.) varies with micropollutants of interest. In presence of higher chloride concentration from the ammonia source, RCS generated •OH radicals and consumed by RNS to form NO3−, showing the impact of the ammonia source and water matrix on UV/NH2Cl performance.
author2 Shane Allen Snyder
author_facet Shane Allen Snyder
Seah, Zi Quan
format Thesis-Master by Research
author Seah, Zi Quan
author_sort Seah, Zi Quan
title The role of reactive chlorine and nitrogen species in micropollutant degradation in UV/monochloramine AOP
title_short The role of reactive chlorine and nitrogen species in micropollutant degradation in UV/monochloramine AOP
title_full The role of reactive chlorine and nitrogen species in micropollutant degradation in UV/monochloramine AOP
title_fullStr The role of reactive chlorine and nitrogen species in micropollutant degradation in UV/monochloramine AOP
title_full_unstemmed The role of reactive chlorine and nitrogen species in micropollutant degradation in UV/monochloramine AOP
title_sort role of reactive chlorine and nitrogen species in micropollutant degradation in uv/monochloramine aop
publisher Nanyang Technological University
publishDate 2024
url https://hdl.handle.net/10356/173492
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