Sodium hypochlorite typical production

Lithium hypochlorite can be obtained by mixing strong solutions of sodium hypochlorite with lithium chloride. This results in partial precipitation of sodium chloride. The product obtained by evaporation of supematent solution typically contains 30% lithium hypochlorite (LiOCl), 34% sodium chloride and other salts. Chlorinated trisodium phosphate is a hydrated complex having chemical formula (Naj PO. H3O) NaOCl and contains approximately 4% available chlorine. Gener-... 

Two general types of bleaches have been used in ADDs hypochlorite and peroxygen bleaches. Chlorine bleaches refer here to complexes that either contain or deliver hypochlorite (OC1-) in solution. The compounds used in detergent products are typically alkali metal or alkaline earth hypochlorites, with liquid sodium hypochlorite being the most common. Solid calcium hypochlorite has also received attention, although its low solubility and its contribution of Ca2+ to the wash liquor has limited its use in LADD products. Generally, NaOCl is added in amounts resulting in 1 to 2% available chlorine. 

In a mercury cell, the brine is removed before sodium hydroxide is formed, thus the resulting solution typically contains <50 mg kg of sodium chloride and even lower concentrations of other salts. The amount of water added to the decomposer is usually adjusted to make 50% sodium hydroxide, or rarely 73% sodium hydroxide. These solutions are simply cooled and filtered without the need for evaporation. This avoids contamination by nickel and other metals, which occurs during the concentration of sodium hydroxide from diaphragm cells. Because rayon production requires low concentrations of metals and salt, mercury cell sodium hydroxide is also called rayon grade. However, mercury cell sodium hydroxide typically contains 10-50 pg kg of mercury. Some of this mercury ends up in hypochlorite products, although the concentration is reduced by dilution and processing operations such as filtration. 

Sold as bleach cleaners, a genuine new generation of hypochlorite-based products appeared in 1993 on the European household market. They have been introduced in different fragranced versions (eucalyptus type, lemon, lavender) and sold as gel or 2-in-1 products which clean and disinfect. The typical surfactant level may range up to 3% (where amine oxide and soap are quite often used) combined with a sodium hypochlorite content up to about 2%. 

Products of other chemical treatment, such as - oxidized starches by treatment with sodium hypochlorite as well as white dextrins (-+dextrins), are frequently also termed t. The term - soluble starch, frequently used, is incorrect with respect to the typical properties of this group of modified starches. Usually, t. are not classified as - starch hydrolysis products because of their typical macromolecular starch properties. 

Most hypochlorite production is in the form of the sodium compound, which will be the focus of our discussion. There will also be a short note on calcium hypochlorite (Section 15.3.4). Figure 15.14 shows a typical flowsheet for production of NaOCl solution [55]. We note here that the compound is more properly designated NaQO. Industry practice, however, favors the form NaOCl. 

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