Abstract
This paper investigated the effect of H +-form high silica ZSM-5 (HZSM-5) zeolites on bromate formation. HZSM-5 zeolites with different Si/Al molar ratios (i.e., 25−300) were tested taking ozonation alone as control. The zeolites were more effective in reducing bromate formation for the filtered surface water than CeO 2, a former reported oxide that can reduce bromate formation at slightly acidic pH. The reduction efficiencies were not closely related to their Si/Al ratios. The HZSM-5 (Si/Al = 300) selected for detailed studies effectively reduced bromate formation by 58% for the filtered water, and also enhanced the removal of dissolved organic carbon (DOC) during ozonation. The efficiency of the HZSM-5 in reducing bromate formation increased with ozone dose (0.38−1.16 mg O 3 mg −1 DOC) and pH (6.6−9.3). The HZSM-5 adsorbed OBr − (one of the critical intermediates in bromate formation) quickly with an adsorption capacity of 54 mg g −1, but had no adsorption for ozone, Br −, HOBr and BrO 3 - . It also significantly inhibited the formation of trace H 2O 2 which was generated from ozone decomposition and had been considered promoting bromate formation at low concentrations during ozonation. The reduction of bromate formation in O 3/HZSM-5 is possibly ascribed to the selective OBr − adsorption in combination with the inhibited H 2O 2 formation.
Published Version
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