1, hydrogen peroxide bleaching status of fifty years since the 20th century, widely applied in the dyeing industry, hydrogen peroxide bleaching process has been industrialized in large-scale production of hydrogen peroxide support, quickly got in the dyeing and finishing production of stable and rapid adoption. Hypochlorite and with the traditional chlorine bleach represented continued progress in the battle, especially with the growing environmental awareness around the world situation, adsorbable organic halogen compounds (AOX) as wastewater emission targets, the obviously further enhanced the advantages of using hydrogen peroxide bleaching process. Second, the hydrogen peroxide bleaching of pure whiteness, good stability, little pollution, no corrosion of equipment, as well as for a variety of fiber and blended fabric bleach, of course, everyone will be welcome. Alkaline hydrogen peroxide bleaching of textiles initially as a catalyst, sodium silicate for the control of hydrogen peroxide by the rate of sub-mediated stabilizing agent, effective bleaching, continued application of this technology for a long time. Until the late seventies, energy conservation and reduce processing costs because the requirements of the development process of pre-treatment process was short some significant changes. Such as the development of one-bath scouring and bleaching, for the cottonseed hull can be fully removed, increased the concentration of caustic soda, put forward the need for the stability of concentrated alkali-resistant agent, hydrogen peroxide bleaching of new technology development, birth of a new support stabilizer, hydrogen peroxide decades technological progress, can be recognized from its bleaching effect and stabilizer development and hypothesis two statements:
(A) the role of hydrogen peroxide bleaching of understanding on the role of hydrogen peroxide bleaching, since the oxygen out of the primary activities of material errors are bleached after what many researchers around the hydrogen peroxide bleaching of the active substance is carried out many tests and a variety of hypotheses put forward up to today There is no consensus, being explored. To dyeing and finishing sector, the majority had accepted hydroxide ion (HOO-) is a hydrogen peroxide bleaching of the active substance is concerned. In alkaline hydrogen peroxide bleaching solution, such as the presence of reaction (1) type shown in H2O2 OH-H HOO-H2O (1) but HOO-PH value of the quantity and, HOO-concentration with the PH value of the rate of increase, however, H2O2 bleaching effect is better when only PH9.5 ~ 10.5. PH value of more than 10.5, the bleaching effect of not only not better, but it decreased, thus it is difficult to HOO-is a reactive substance.
Later, it was suggested that the role of hydrogen peroxide bleaching of free radical reactions, that is, HO · and HOO · high activity, which makes fibers brittle with both losses, they can decompose and produce pigment bleaching effect, also said that the two effects exist This hypothesis has gradually started to be used nowadays. However, it was further challenged, put forward the role of hydrogen peroxide bleaching of superoxide (O-2 ·), which had hydroxyl radical by the (HOO ·) formed from the solution:
HOO · ← ... → O-2 · H (2) HOO · is a mild acid, in water pka value of 4.8, the equivalent of acetic acid, pH 10.5 (ie, the best bleaching range) around almost quantitatively by the type dissociation. When the bleach solution by adding different amounts of hydroquinone, bleaching decreased with the quantity, thus proving the role of superoxide is produced bleaching material. Moreover, the concentration of superoxide generation can be estimated theoretically.
(B) Development and mechanism of stabilizers in alkaline hydrogen peroxide bleaching solution, the added stabilizer is mainly due heavily ion and dust control, contributing to the split decomposition of hydrogen peroxide are generated, then the chain reaction triggered by the free radicals under control (reactive omitted). Experience, hydrogen peroxide bleaching stabilizer should meet the following requirements: 1. Efficient stabilizing effect, 2. On fiber damage, 3. Acid is good, 4. Will not scale, 5. Pure whiteness, 6. May biodegradable, the above six requirements have appropriate specific targets.
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