Disinfection Effects and Disinfection by-products Generation Characteristics of a Continuous Hypochlorous Acid Water Producing Device Using Citric Acid as a pH Control Agent

Abstract

The use of disinfectants and disinfecting devices is becoming increasingly common in homes as they prevent the development and spread of pathogens while improving hygiene. Common disinfectants include chlorine compounds, alcohol, and quaternary ammonium compounds. Among them, chlorine compounds are easily manufactured and commonly used in the form of sodium hypochlorite. When chlorine compounds are dissolved in water, free chlorine divides into hypochlorous acid and hypochlorite ions with different molar fractions depending on solution pHs. Maintaining a high hypochlorous acid fraction by adjusting the solution pH is crucial as hypochlorous acid is more than 100 times more effective as a disinfectant than hypochlorite ions. However, due to the chemical nature of its conversion to hypochlorite ions, hypochlorous acid is not very stable, making it more efficient to prepare and consume it at the time of use. In this study, we used citric acid as a pH adjuster to determine the optimal conditions required for producing electrolyzed water. We built a device capable of continuously producing electrolyzed water containing hypochlorous acid, and we analyzed the efficiency of the produced electrolyzed water using disinfection tests and measurements of disinfection by-products.