Monthly Archives: March 2018


Know Your Chlorine

Chlorine is one of the most commonly used disinfectants for water disinfection. Chlorine can be applied for the deactivation of most microorganisms and it is relatively cheap. Chlorine (Cl2) is one of the most reactive elements; it easily binds to other elements. In the periodic table Chlorine can be found among the halogens.

Watery chlorine should be protected from sunlight. Chlorine is broken down under the influence of sunlight. UV radiation in sunlight provides energy which aids the break-down of underchloric acid (HOCl) molecules. First, the Water molecule (H2O) is broken down, causing electrons to be released which reduce the chlorine atom of underchloric acid to chloride (Cl-). During this reaction an oxygen atom is released, which will be converted into an oxygen molecule: 2HOCl -> 2H+ + 2Cl- + O2

Chlorine is produced from chlorine bonds by means of electrolytic or chemical oxidation. This is often attained by electrolysis of seawater or rock salt. The salts are dissolved in water, forming brine. Brine can conduct a powerful direct current in an electrolytic cell. Because of this current chlorine ions (which originate from salt dissolving in water) are transformed to chlorine atoms. Salt and water are divided up in sodium hydroxide (NaOH) and hydrogen gas (H2) on the cathode and chlorine gas on the anode. These cathode and anode products should be separated, because hydrogen gas reacts with chlorine gas very aggressively. Chlorine-based bleach is applied as a disinfectant on a large scale. The substances are also used to bleach paper. Bleaching occurs as a result of chlorine or hypochlorite oxidation.

About 65% of industrialized chlorine is used to produce organic chemicals, such as plastics. About 20% […]

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