Bleaching general practices

Commercial sodium hypochlorite solutions generally contain 15 to 18 per cent of available chlorine. One gallon per 100 gallons of w ater will therefore make a bleaching liquor which contains near enough to 1-5 g per litre of available chlorine for most practical purposes. Sodium hypochlorite is quite strongly alkaline and there is no risk that the pH can fall below 10, as may happen with bleaching pow der. 

Label all unit operations in general terms, such as mixer, separator, heater, and cooler. Each unit on your flowsheet should perform only one operation, even though in actual practice one machine may perform multiple operations in sequence. Add the necessary streams for water, soap, bleach, and air and list the components in all streams. 

Peroxide is thermodynamically unstable but kinetically rather inert and this explains the need for time or temperature to achieve effective bleaching. As a general rule, the bleaching performance of persalts increases as the pH is raised [i.e., as more OOH is generated (piC, of hydrogen peroxide is 11.6)]. Loss of actives due to transition metal action or thermal instability may alter the pH of maximum activity in practice. The optimal conditions for maximum activity of activated systems are discussed in Sec. IV. 

Bleach Liquor 12.5% chlorine commercially available 38 9 Resistant little or no change in weight small effect on mechanical properties generally suitable for practical use PSU 1000 Quadrant EPP... 

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