Monitoring free chlorine and free bromine in aquarium seawater treated by ozone

Abstract

Free chlorine (FC) and free bromine (FB) produced during ozonation treatment of aquarium seawater pose a serious threat to the health of ornamental aquatic animals, but little is known about the concentration levels of these chemicals in aquarium facilities. In this study, a highly selective and sensitive analytical method based on the derivatization of FC and FB to corresponding 4-halo-2,6-dimethylphenols by 2,6-dimethylphenol was developed. The formed halo-derivatives were extracted by hexane and subsequently quantified by gas chromatography-mass spectrometry. The calibration curves showed good linearity (r 2 > 0.999) in a broad concentration range of 2.1-4200 mg L À1 for FC and 3.3-1700 mg L À1 for FB. The method detection limits (S/N ¼ 3) were determined to be 62.7 and 71.6 ng L À1for FC and FB, respectively. The developed method exhibited good recovery, selectivity, precision and was successfully applied to monitor the formation and decay of FC and FB in ozonated seawater. During the ozonation process, the formation of FB dominated, while much less chloride was oxidized to FC; FB decayed much faster than FC. The concentrations of FC and FB in various animal tanks of Beijing Aquarium were also monitored. The results show that 30.1-56.4 mg L À1 FC and 26.5-730.7 mg L À1 FB were present in aquarium tanks, revealing that the health of aquatic animals (particularly fish, jellyfish, and coral) was under severe threat.

Life support systems and aquatic communities in public aquariums

“…In addition, ozone can also break down toxic ammonia into non-toxic nitrates [69]. This technology is commonly used in public aquarium and aquaculture for controlling various disease and disinfection [70], [71]. Ozone has a positive impact for the oceanarium which is to reduce turbidity, eliminate odors and colors [72].…”

Formation of disinfection byproducts in a recirculating mariculture system: emerging concerns

“…However, ozonation leads to the formation of free chlorine and free bromine in seawater, which in turn promotes the formation of THMs and HAAs. 11,18 Our monitoring results show that the concentrations of THM4 and HAA5 were below the USEPA-regulated MCLs for drinking water, i.e., 80 and 60 mg L…”

Enhanced formation of bromate and brominated disinfection byproducts during chlorination of bromide-containing waters under catalysis of copper corrosion products

“…Free bromine (e.g., HOBr/OBr À ) was analyzed according to our earlier developed method (Qiang et al, 2012) , respectively. The dissolved copper content was determined by an Agilent 7500 inductively coupled plasma mass spectrometer.…”