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Title: Byproduct formation in heterogeneous catalytic ozonation processes
Heterogeneous catalytic ozonation (HCO) is a promising advanced oxidation process (AOP) that can effectively degrade recalcitrant organic pollutants. While research efforts have been mainly devoted to the development of different catalysts to enhance the process efficiency, more studies are needed to investigate and address the other challenge faced by AOPs, i.e. generation of harmful byproducts. Bromate is the major inorganic byproduct of concern when ozone is involved. While most studies have reported less bromate formation in HCO than ozonation alone, the effects of catalysts depend on their interaction with O 3 and the dominant bromate formation pathway (direct O 3 oxidation vs. indirect ˙OH oxidation) in the system. Production of H 2 O 2 and cyclic redox reactions on the catalyst surface can also reduce different Br species leading to a lower bromate yield. Generation of organic byproducts (OBPs; e.g. aldehydes, keto-acids, carboxylic acids) in HCO depends on the reactivity of precursors ( e.g. dissolved organic matter/DOM) and OBPs with O 3 /˙OH, interactions between DOM/OBPs and catalysts, characteristics of DOM, and O 3 dose. HCO generally increased the removal of dissolved organic carbon (DOC) and the biodegradability of the bulk organics. HCO treatment may also decrease the formation potential of some disinfection byproducts (DBPs) such as trihalomethanes (THMs) and haloacetic acids (HAAs) but may increase the brominated species of the DBPs and also the formation potential of haloacetonitrile (HAN) under certain conditions. This review discusses the current status of studies on both organic and inorganic byproduct formation in HCO as well as transformation of bulk organics and the effects on DBP formation in the downstream disinfection process, and further provides recommendations for future research and development. A standardized experimental protocol and rigorous experimental design is important to deepen our understanding and gain insights on the byproduct formation in HCO from different studies collectively.  more » « less
Award ID(s):
1606117
NSF-PAR ID:
10407694
Author(s) / Creator(s):
Date Published:
Journal Name:
Environmental Science: Advances
Volume:
2
Issue:
4
ISSN:
2754-7000
Page Range / eLocation ID:
558 to 569
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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