Bleaching concepts

Based on the tubular fabric mercerizing machine, Domier, GmbH, has developed a combinable mercerizing and bleaching concept for tubular warp knitted fabrics. The combined mercerizing/bleaching machine (Fig. 9-23) comprises im-... 

Closed-Mill Concept. The closed-mill concept, or water circuit closure, has been studied by the pulp and paper industry for many years. In some parts of the paper manufacturing process, up to 98% of the water is recycled within the process, eg, the wet end of the paper machine. However, in the pulp mill, especiaUy kraft mills, effluents are produced owing to the need to purge from the system various metals that come in with the wood, as weU as organic by-products from the pulping process, additives, and especially chloride ions that originate in the bleach plant. 

A central aspect of the PIE concept is that the dye and resist exposures should be completely separated (9,15) any departure from this condition makes the system more like CEL and lowers its performance. Further bleaching of the anthracene is of course eliminated simply by removing oxygen the bleaching reactions described above (e.g. Figure 8) are much lower in efficiency and therefore irrelevant insofar as pattern transfer is concerned. However, "antibleaching" due to the loss of oxygen from the anthracene peroxide upon DU V irradiation (47) is a concern it constitutes a dose-dependent loss of contrast. 

Crabtree and coworkers used the disappearance of color to monitor the activity of 12 potential catalysts for hydrosilation reactions [6], The group used alkenes and imines with ferrocenyl and pyrimidyl substituents at either end as colored reactants. On hydrosilation the color is bleached, because conjugation between the electron donor and acceptor groups is reduced. The bleaching is easily observed by eye and can be recorded quantitatively by means of a digital camera (Figure 5.4.1). By use of this method, the known Wilkinson catalyst was identified in a proof-of-concept experiment. A palladacycle, [ Pd (o-tolylfi PQ H4 OAc 2, usually used in Heck reactions, was also found to be catalytically active. 

As far as quantitative chemical derivatization GC analysis is concerned, it is necessary to mention especially the work of Gehrke and his collaborators, who specified the fundamental concepts of quantitative GC analysis combined with the chemical derivatization of sample compounds and applied them to the accurate determination of the twenty natural protein amino acids and other non-protein amino acids as their N-TFA-n-butyl esters [5 ], the urinary excretion level of methylated nucleic acid bases as their TMS derivatives [6], TMS nucleosides [7] and other investigations. Further examples include a computer program for processing the quantitative GC data obtained for seventeen triglyceride fatty acids after their transesterification by 2 NKOH in n-butanol [8], a study of the kinetics of the transesterification reactions of dimethyl terephthalate with ethylene glycol [9] and the GC-MS determination of chlorophenols in spent bleach liquors after isolation of the chlorophenols by a multi-step extraction, purification of the final extract by HPLC and derivatization with diazoethane [10]. 

Neutral amine ligands are often applied with transition metals in higher oxidation states in polar solvents. This concept combined with the resistance of amines against oxidative conditions led to the development of novel bleaching catalysts (Structures 1-3) for washing powders by Unilever [1],... 

Our results support the concept that the primary charge separation in heliobacteria consists of the transfer of an electron from P7, to an acceptor absorbing near 670 nm, which is presumably a Bchl c-like or Chi a-like pigment (6). The decay time of the bleaching at 668 nm is shortened by a factor of 2.5 upon cooling from 300 K to 15 K. This would mean that the second step in the charge separation, electron transfer from the... 

This chapter will cover low-temperature bleach activators, catalysts utilizing peroxide or atmospheric oxygen for the oxidation reaction, and oxygen transfer agents that act as performance boosters for common bleach systems. Optimum conditions of use to maximize performance and avoid negative secondary reactions are described. Special attention is given to the various finishing processes, application forms, and delivery concepts that enable sensitive bleach components to be incorporated in household products, improve stain removal performance, and deliver an attractive appearance for consumers. 

For pretreatment of stains, bleach activators in stick form are claimed [193], consisting of a water-soluble surfactant binder and TAED powders. The activator is applied directly on the stain before the wash process and activated by a persalt-containing detergent. A similar concept based on single-dosed laundry boosters was used some time ago in Europe. It comprised a nonsoluble sheet of nonwoven material, which contained a high amount of bleach activator but no peroxide source [194]. To work, the sheet had to be added to persalt-containing detergents. 

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