Original scientific paper
Effects of pH and alkalinity on ozonation of bromide and chloride in seawater
Gordan Grgurić
Peter J. Egli
; The Richard Stockton College of New Jersey, Pomona, NJ 08240, SAD
Abstract
A series of laboratory experiments were performed in which unbuffered and buffered solutions of NaBr and NaCI were exhaustively ozonated, The production patterns and relative abundances of the products were compared in order to quantify the roles of pH, carbonate system and borate system in ozone reactions with these two halides in seawater. Concentrations of hypohalites in solutions where pH was buffered in the range 8.6-8.8 were consistently lower than those in the equivalent unbuffered solutions. Bromate production rates in unbuffered NaBr solution, NaBr solution buffered with 3 meg/L carbonate alkalinity, and that buffered with 3 meg/L borate alkalinity were, respectively, 1.30 uM/min, 1.58 ěM/min and 0.83 uM/min. Our finding that, relative to carbonate alkalinity, borate alkalinity enhances the production of hypobromite while simultaneously depressing bromate formation, may have
important consequences for seawater facilities such as aquaria and mariculture that use borate buffers. Hypobromite produced during ozonation in such systems is a desired secondary disinfectant, due to the very short half-life of dissolved ozone in seawater. The use of borate buffers may thus serve to enhance the potential for disinfection while simultaneously diminishing the unwanted bromate accumulation in these environments.
Keywords
Ozone; Seawater; pH Buffers; Hypobromite; Hypochlorite; Bromate.
Hrčak ID:
344550
URI
Publication date:
20.12.2021.
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