Peracetic acid bleaching agent

Synthetic Fibers. Most synthetic fibers are sufficientiy white and do not requite bleaching. For white fabrics, unbleached synthetic fibers with duorescent whitening agents are usually used. When needed, synthetic fibers and many of theit blends are bleached with sodium chlorite solutions at pH 2.5—4.5 for 30—90 min at concentrations and temperatures that depend on the type of fiber. Solutions of 0.1% peracetic acid are also used at pH 6—7 for 1 h at 80—85°C to bleach nylon. 

Iodoxybenzene has been prepared by the disproportionation of iodosobenzene,4Hi by oxidation of iodosobenzene with hypo-chlorous add or bleaching powder,7 and by oxidation of iodobenzene with hypochlorous acid or with sodium hydroxide and bromine.8 Other oxidizing agents used with iodobenzene include air,3 chlorine in pyridine,9 Caro s acid,19-11 concentrated chloric acid,15 and peracetic acid solution.13 Hypochlorite oxidation of iodobenzene dichloride has also been employed.14... 

The mechanism of activation is believed to be as follows. In an alkaline medium, hydrogen peroxide yields the perhydroxide anion (Scheme 10.22), which reacts with TAED (10.86) to form diacetylethylenediamine (10.87) and the peracetate anion (10.88) as in Scheme 10.30 [244]. At pH 8-9, the peracetate anion is in equilibrium with free peracetic acid, as in Scheme 10.31 [244]. The peracetic acid reacts with the peracetate anion to form nascent oxygen which is the active bleaching agent, as in Scheme 10.32 [244]. Further possible activators suggested by Kleber [244] include ... 

The military also identifies the following "nonstandard" decontaminants Detrochlorite (thickened bleach mixture of diatomaceous earth, anionic wetting agent, calcium hypochlorite, and water), 3% aqueous peracetic acid solution, 1% aqueous hyamine solution, and a 10% aqueous sodium or potassium hydroxide solution. 

Peracetic acid or its anion, produced in situ from A, A, A, A -tetraacetylethylenediamine, in the presence of hydrogen peroxide, in slightly alkaline solution (equation 14), is an effective bleaching agent used in pulp manufacture and laundering. Household washing solution formulations contain perborate and activators that produce peracetic acid of bleaching effect . ... 

Peracetic acid is the most widely used organic peroxy acid. It is a strong oxidizer, which could he used in disinfection and bleaching agent. Peracetic acid can be synthesized from acetic acid and hydrogen peroxide. The formation of peracetic acid takes place in the equilibrium reaction (1). In order to accelerate the reaction rate, acid catalyst is needed (Swem, D., 1970). Conventionally homogeneous sulphuric acid catalyst is used. The reaction scheme is shown in Eq. (1)... 

The peroxide anion reacts with TAED to form DAED (diacetylethylenediamine) and peracetic acid anions. At pH 8-9 the peracetic acid anion is in equilibrium with the free peracetic acid. This equilibrium peracetic acid oxidises its own per anion to form active oxygen, which acts as a bleaching agent [88]. 

Merits and demerits of bleaching with peracetic acid The advantages of peracetic acid as a bleaching agent are ... 

Peracetic acid can also be used for bleaching polyester/cotton blended fabrics with a solution containing 4 g/1 peracetic acid, 1 g/1 tetrasodium pyrophosphate (stabiliser) and 1 g/1 wetting agent with a liquor ratio of 5 1. Peracetic acid has a pH of about 1.5 and the bleaching bath solution is adjusted to pH 5.5 with the help of dilute alkali. The material is entered cold and run for 10 min. Then the temperature is raised to 65-70 C in 15 min and bleaching is continued at this temperature till the concentration of peracetic acid drops to 0.09 g/1. The fabric is then washed thoroughly... 

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