The influence of pH and salt concentrations on the bactericidal effects of strong acidic electrolyzed water
2004
Iwasawa, A. (Showa Univ., Yokohama (Japan). Fujigaoka Hospital) | Nakamura, Y. | Inoue, K. | Niwa, T. | Nishimoto, Y.
Strong Acidic Electrolyzed Water (SAEW) is functional water with a bactericidal effect made by electrolysis with less than 0.1% NaCl or KCl on the anode side. The Strong Electrolyzed Water Association (SEWA) has provided that for SAEW. the pH is 2.2-2.7 and the concentration of available chlorine is 20-60 mg/L. In this study, we intended to clarify the effects of pH and salt concentrations on the minimum concentration of available chlorine using various SAEW and chemical acidic sodium hydrochloride (NaOCl) solutions. Flash bactericidal effects were influenced by pH and salt concentrations in SAEW with 0.30 mmol/L concentrations of available chlorine. At 0 mmol/L salt concentration, flash bactericidal effects were seen, with S. epidermidis at a pH of 2.3-2.8, P. aeruginosa at a pH of 2.3 or less, and E. coli at a pH of 2.3-3.3. At 13.5 mmol/L salt concentration, flash bactericidal effects were seen with S. epidermidis and E. coli at a pH of 3.0, and P. aeruginosa at a pH of 2.5 or less. Bactericidal effects deteriorated with an increase in salt concentration levels, and at 100 mmol/L salt concentration, no effect was recognized with all tested bacteria. The pH at which the ratio of hypochlorous acid (HClO) present in all available chlorine becomes greatest shifts to the high pH side with an increase in salt concentration.
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