Eisei kagaku
Print ISSN : 0013-273X
Effects of Isocyanuric Acid on the Poliovirus Inactivation with Hypochlorous Acid
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1998 Volume 44 Issue 6 Pages 442-450


Isocyanuric acid (H3Cy) has been used in outdoor pools as a chlorine stabilizer. For the evaluation of the influence of H3Cy on the disinfection with chlorine, the inactivation rates for poliovirus (Lsc, 2ab strain) with sodium hypochlorite and dichloroisocyanuric acid (Cl2HCy) (0.1-2.0 mg/l as available chlorine) containing various concentrations of H3Cy (0.7-30 mg/l) were determined at pH 7 and 20°C. Two types of virus suspensions, one in a cell maintenance medium (MEM) and the other in phosphate buffered saline (PBS), were used to compare the effects of H3Cy on the chloramine formation and its virus inactivation efficacy. The residual chlorine in the test solutions was determined simultaneously by the DPD method. The addition of H3Cy had few effects on the chloramine formation and on the chlorine consumption. The chloramine formed in the test solutions showed less virus inactivation efficacy. The influence of H3Cy on the virus inactivation rates was observed when free residual chlorine was determined in the test solutions. In the experiments of a virus suspension in PBS with chlorine at 0.4 mg/l as available chlorine, the rates decreased with an increase in H3Cy concentrations, although the amounts of free residual chlorine in the test solutions were the same. The plots of survival ratios at each contact time against the H3Cy/chlorine ratios showed good linearity. The product of the contact time and the slope of each line became nearly constant. These results suggest that the inactivation rates were dependent on the H3Cy/chlorine ratios and the contact time, and also suggest that the change of the H3Cy/chlorine ratio might shift the hydrolysis equilibrium between hypochlorite and chlorinated isocyanuric acid.

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