Whitening with Bleach

In contrast to dyes, fluorescent whiteners are not appHed exclusively in special processes, but often in combination with bleaching and finishing steps. Fluorescent whiteners used in such processes must be stable and should not interfere with the operation. 

After the chemical treatment, the pulped wood is removed, washed, and screened. Unbleached, brown-colored paper is made directly for this material. Most whitened or bleached paper is made by the treatment of the pulp with chlorine, chlorine dioxide, hypochlorite, and/or alkaline extraction. In general, sulfate-pulped paper is darker and requires more bleaching and alkaline extraction to give a white pulp. 

Whitening of teeth can occur by two mechanisms. One method is mechanical, in which an abrasive is used to remove debris from the tooth. The other method involves either the use of peroxides, which react with water to form free oxygen radicals that help to whiten the teeth or a combination of mechanical and chemical actions. This latter mechanism is found with bleaching agents and is longer lasting than whitening procedures. 

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. 

Fluorescent whitening agents (LD) Create a brightening effect Substantivity on fabrics Compatibility with other ingredients like bleaches Bistriazinyl derivatives of 4,4 -diamino-stilbene-2,2 -disulfonic acid 0.1-0.5%... 

Whenever you start a car, use a battery-powered device, apply a rust inhibitor to a piece of metal, or use bleach to whiten your clothes, you deal with some aspect of electrochemistry. Electrochemistry is that branch of science that involves the interaction of electrical energy and chemistry. Many of our daily activities use some form of electrochemistry. Just imagine how your life would be in a world without batteries. What immediately comes to mind is the loss of power for our portable electronic devices. While this would certainly be an inconvenience, consider the more critical needs of those with battery-powered wheelchairs, hearing aids, or heart pacemakers. In this chapter, we examine the basic principles of electrochemistry and some of their applications in our lives. 

Did you know that many of the chemical products in your home are hazardous, too For example, common household bleach, when used as directed, is safe for disinfecting and whitening clothing. Hazard labels on bleaching products, however, warn against mixing bleach with acids, household ammonia, or products that contain these chemicals. Bleach, when combined with acids, produces toxic chlorine gas. The products of combining bleach with ammonia are explosive. 

WATER — Bleaching Water — The Azoth of the Adepts, with which they say that the Laton must be whitened, and its darkness removed. 

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