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Halazone tablets have been used to disinfect water for drinking, especially where treated tap water is not available. A typical dosage is 4 mg/L.[5][6]
Halazone tablets were commonly used during World War II by U.S. soldiers for portable water purification, even being included in accessory packs for C-rations until 1945.[7]
Halazone has largely been replaced in that use by sodium dichloroisocyanurate. The primary limitation of halazone tablets was the very short usable life of opened bottles, typically 3 days or less, unlike iodine-based tablets which have a usable open bottle life of three months.[citation needed]
Dilute halazone solutions (4 to 8 ppm of available chlorine) has also been used to disinfect contact lenses,[8] and as a spermicide.
Mechanism of action
Halazone's disinfecting activity is mainly due to the hypochlorous acid (HClO) released by hydrolysis of the chlorine-nitrogen bonds when the product is dissolved in water:[8]
(R1)(R2)NCl + H
2O → HOCl + (R1)(R2)NH
The hypochlorous acid is a powerful oxidizer and chlorinating agent that destroys or denatures many organic compounds.
https://en.wikipedia.org/wiki/Halazone
Military Canteen Water Purification
The first field treatment for water was ancient and primitive: use a cloth to strain out impurities, then boil the water for at least one minute. While this was effective in preventing many water borne diseases, it required troops to concentrate attention on their water for significant time and to expose their position by lighting fires. A better way was urgently needed. Army researchers looked for chemical treatments as a solution.
The purification of drinking water by the use of liquid chlorine was developed in 1910 by Major Carl Rogers Darnell, Professor of Chemistry at the U.S. Army Medical School. He later designed a purification filter for field use in World War I. Around the same period, Major William Lyster used a solution of calcium hypochlorite in a linen bag (Lyster Bag) to treat water. Small vials of chlorine solution were issued to troops, prior to World War II, for water treatment. A cap-full of chlorine bleach, put into a canteen of water, is an emergency method still used when nothing else is available. Older veterans remember standing in line to get bleach from their squad leader.
Chemical treatments for soldiers' canteen water have been continuously studied and improved, resulting in a series of standard treatment chemicals issued to the individual soldier, as well as methods for treatment of group water sources.
Halazone Tablets for Military Canteens
Halazone (4 dichlorosulfamyl benzoic acid) is a white, crystalline powder made from a chlorine compound. It imparts a strong taste and smell of chlorine to the water. Halazone was developed in the early 20th century, and was used during World War I. By 1940, Halazone tablets were available as a conventient and effective water treatment for individual soldiers. Halazone was supplied in small brown glass bottles (packed with K rations and C rations during WW II) and training was provided with proper instructions in their use. Halazone was a major medical item of supply during World War II.
https://olive-drab.com/od_medical_other_waterpurif.php