In 1814 by Sir Humphrey Davy. He produced the gas by pouring sulphuric acid (H2SO3) on potassium chlorate (KClO3). Than he replaced sulphuric acid by hypochlorous acid (HOCl). In the last few years this reaction has also been used to produce large quantities of chlorine dioxide. Sodium chlorate (NaClO3) was used instead of potassium chlorate.
2NaClO3 + 4HCl ® 2ClO2 + Cl2 + 2NaCl + 2H2O.
In 1816 a similar discovery was announced from independent research of the same gas which was designated as “deutoxide of chlorine” [Von Stadion 1816]. Various other workers were involved in this early research to determine the nature of the gases produced from various actions of acids on chlorates. All of these researchers remarked in some way upon the unstable nature of the gas, as a number of small explosions resulted, some sufficiently violent enough to break the experimental glassware. Various recommendations were made to ensure that further experimentation by others would be done safely [Jacquelain 1825; Soubeiran 1831; Davy 1834; Von Mons 1835; Millon 1843].
In 1843, the reaction of potassium chlorate with hydrochloric acid to produce a green-yellow gas was reported [Millon 1843]. The gas was then absorbed in alkaline solution to obtain chlorite and chlorate. This green yellow gas became known as “Millon’s gas.”
In 1858, a new method for making “peroxide of chlorine” was reported, whereby potassium chlorate and oxalic acid were heated together. If the heat and the relative amounts of reactants were carefully controlled, this yellow gas could be formed [Calvert and Davies 1858]. In 1875, euchlorine was found to be a mixture of chlorine dioxide with varying amounts of chlorine [Pebal 1875]. This finding was confirmed independently by another researcher [Garzarolli-Thurnlackh 1881].
The first known commercial process for preparing chlorine dioxide gas was developed in the 1930’s, and its use as a bleaching agent expanded rapidly in the industrial sector. In 1941 the oxidizing power of chlorine dioxide was first used for taste and odor control in a water treatment plant in Niagara Falls, New York. The successful use of ClO2 as a water disinfecting agent in New York led to the rapid expansion of its use for this purpose. Chlorine dioxide was introduced as a drinking water disinfectant on a large scale in 1956. ClO2 is now widely used in water treatment,
Chlorine Dioxide (CAs No 10049-04-4) is an approved and allowed substance for human and animal consumption according to EU, USEPA, WHO standards and many national drinking water regulations.