Volatilization of hypobromous acid in cooling wate

The primary objective of this research was to determine the Henry's law constant for hypobromous acid (HOBr). The newest oxidizing biocides in cooling tower systems are based on bromine rather than chlorine because bromine is more effective at higher pH. The volatility of bromine is very significant as a loss from the system. Only one other researcher attempted to measure the Henry's law constant for hypobromous acid and the results were suspect.;The Henry's law constant for hypobromous acid was measured two independent ways. The first method was the static bottle test in which a measured small amount of hypobromous acid was added to a one liter bottle and allowed to reach equilibrium with the enclosed air, the loss of hypobromous acid from the liquid was measured. The Henry's law constant for this method was 0.21 atm. The second method involved a pilot cooling tower and a mathematical model based on mass transfer. The model was calibrated and verified using ammonia. The Henry's law constant for hypobromous acid was calculated from the mass transfer equations based on the average data from the individual runs. The resulting average value was 0.16 atm. Comparison of the results of two independent methods confirms the validity of the constant. These results indicated volatilization of hypobromous acid is a major loss pathway in cooling tower systems.