Degradation of 2,2-Bis(bromomethyl)-1,3-propanediol and bromate formation in UV/persulfate, UV/peroxymonosulfate and UV/TiO2 processes

Abstract

Debromination occurs when brominated flame retardants (BFRs) are decomposed by advanced oxidation processes (AOPs). As the result, bromide is released to water and is potentially oxidized to bromate by the AOPs. As the by-product, bromate is classified as potentially carcinogenic and its formation in the degradation of BFRs was easily been ignored. Since the EPA regulation of bromate in the drinking water is as low as 10 μg/L, the assessment on the bromate formation in the degradation of BFRs by AOPs is necessary and important. In this study, 2,2-Bis(bromomethyl)-1,3-propanediol (BBMP), one kind of the BFRs, was tested as the target compound. The debromination and the bromate formation in the BBMP degradation by UV/Persulfate, UV/Peroxymonosulfate (PMS) and UV/Titanium dioxide (TiO₂) processes were monitored at different oxidant/photocatalyst dosages and pH. Under the test conditions, at low levels of the BBMP debromination (40 – 70%), the bromate formation in three processes were insignificantly low, while as the most time efficient process, the required contact time for the UV/Persulfate process to achieve the debromination was about 2.4 times shorter than that for the UV/TiO₂ process, which was the most time consuming process. At the high level of BBMP debromination (80%), the required contact time for three processes became similar while the bromate formation in the UV/Persulfate process was significantly larger than that in the other two processes. As the result, the UV/PMS process was recommended to achieve the high level of BBMP debromination and the UV/Persulfate process was recommended to achieve low levels of the BBMP debromination. In the UV/Persulfate and UV/PMS processes, increasing the oxidant dosage enhanced both the BBMP debromination and the bromate formation, while in the UV/TiO₂ process, introducing TiO₂ into the UV reactor initially increased then decreased the BBMP debromination and the bromate formation. Increasing the solution pH enhanced the debromination of BBMP and generally inhibited the bromate formation.

Date of Award	2013
Original language	English
Awarding Institution	The Hong Kong University of Science and Technology