Alterations in pH and active chlorine purport resulting from package and storage local of sodium hypochlorite solution in different concentrations

Abstract

The objective of the present study was to verify the influence of pH, package and place of storage in chemical stability of different concentrations of sodium hypochlorite solution. Fifteen liters of the sodium hypochlorite solution were prepared from the dilution of an intent solution for each one of following concentrations: 0.57%, 1.16%, 2.98% and 6%, then totalizing sixty liters. After the solutions preparation, they were stored n five types of flasks (glass amber, transparent glass, amber plastic, transparent plastic and opaque white plastic) and in three different places (room lighting, ambient conditions protected from the light, and refrigerator) for an experimental time of 180 days. The pH analysis was accomplished in 1, 7, 15, 30, 60, 90, 120, 150 and 180 days of storage, by means of pHmeter. The chlorine content was analyzed by means of the iodometric method in triplicate in the beginning of the experiment and after the 180 days of storage. It was observed that all the pH values found were superior to 11, therefore, being favorable to the stability of sodium hypochlorite solutions analyzed. The factors which interfered in the chemical stability of the analyzed solutions were the flasks and the place of storage. In relation the storage flask, glass or amber plastic must be used and stored them in refrigerator as well.