Chlorine-based bleaching

After World War I, other chlorine-based bleaches were developed. In 1921 the use of chlorine dioxide for bleaching fibers was reported followed by the development of the commercial process for large-scale production of sodium chlorite. In 1928 the first dry calcium hypochlorite containing 70% available chlorine was produced in the United States. This material largely replaced bleaching powder as a commercial bleaching agent. 

Be sure to use the least toxic (fragrance free) detergents possible, and, of course, always avoid chlorine-based bleaches. Natural laundry detergents (which often contain borax), and natural bleaches are available (more and more often right in your grocery store) from brands like Ecover and Seventh Generation, as well as the Web sites below. (While were on the subject of clothes, take whatever hand-me-downs are offered, and don t be shy about asking for more. Most people are thrilled for the chance to recycle.)... 

Paper Production is dominated by sulphate-mass and, in some countries, chlorine-based bleaching resulting in waste water strained with oxygen-consuming pollutants and chloroorganics, for example dioxins. 

French chemist Claude-Louis Berthollet, developer of a chlorine-based bleach. 

Enzymes have very relevant applications in the pulp and paper industry now threatened by environmental regulations. Hemicellulases are being currently used in wood pulp bleaching to partially substitute chlorine-based bleaching procedures... 

Modern chlorine-based bleaching agents include elemental chlorine (CI2 gas), a variety of hypochlorites (OCl ), certain N-chlorinated organic compounds, and chlorine dioxide (CIO2). The first three bleaching agents all hydrolyze to produce hypo-chlorous acid in aqueous solution, according to the equilibria in reactions [I]-[III]... 

You can bleach hair by using hydrogen peroxide to oxidize these colored pigments to their colorless forms. However, bleached hair becomes weaker and more brittle, because the hair protein is broken down into lower molecular weight compounds. Perborate compounds, which tend to be more expensive than bleach, and chlorine-based bleaches are also sometimes used to bleach hair. 

This application is driven by the perceived need to replace chlorine-based bleaching agents in order to avoid the presence of harmful chlorinated organics either in the paper or in the effluent. 

Sodium hypochlorite is a more convenient and efficient bleach than hydrogen peroxide. However chlorine-based bleach can suffer from the drawback that potentially biologically active materiaL i.e. sensitisers. may be generated when it is used for bleaching alcohol ethoxy sulphates and aipha-Qiefin. syipbonatss. 

He immediately noted the suffocating odor of the gas. Scheele also discovered that chlorine solutions could bleach cotton cloth. Within a few decades, chlorine-based bleaches became major items of commerce. Currently, chlorine is the most commercially important halogen. 

Q3 Aqueous sodium chlorate(i), NaOCI, the most common active ingredient in chlorine-based bleaches, oxidizes coloured materials to colourless products while being reduced to the chloride ion. It will also oxidize sulfur dioxide to the sulfate ion. a i Deduce a balanced equation for the... 

All these were made using chlorine. Note that it is dangerous to mix chlorine-based bleaches and germ-killers with other kinds. There could be an explosive reaction. 

Other chlorine-based bleaches are extensively used in industry, such as sodium chlorite (NaC102) and gaseous chlorine dioxide (CIO2). Occasional applications of highly diluted chlorite solutions [which may be partially in the form of chlorous acid (HCIO2), depending on the pH] are found in the oral hygiene area. 

About 50% of the world s production of hydrogen peroxide in 1994 was used for pulp-and paper-bleaching. Other bleaching applications are becoming more important as hydrogen peroxide is seen as an environmentally benign alternative to chlorine-based bleaches. 

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