Why Is CLO2 Very Different From Other Disinfectants?
What is Chlorine dioxide (ClO2)?
CIO2 is a yellow green gas from one atom of chlorine and two atoms of oxygen. CIO2 is very different in its chemical structure and behavior from Chlorine. It is 10 times more soluble in water than Chlorine It also has an odd number of valence electrons (19) therefore it is a paramagnetic radical according to Lewis theory on molecules with uneven number of electron.
How does CIO2 work to be Environmentally Friendly?
CIO2 oxidizes therefore produces harmful by-products.
(HAAs) haloacetic acids
The above by products are harmful to humans, animals, aquatic lives and the environment.
By comparing the oxidation strength and oxidation capacity of different disinfectants, one can conclude that chlorine dioxide is effective at low concentrations. Chlorine dioxide is not as reactive as ozone or chlorine and it only reacts with sulphuric substances, amines and some other reactive organic substances. In comparison to chlorine and ozone, less chlorine dioxide is required to obtain an active residual disinfectant. It can also be used when a large amount of organic matter is present.
The oxidation strength describes how strongly an oxidizer reacts with an oxidable substance. Ozone has the highest oxidation strength and reacts with every substance that can be oxidized. Chlorine dioxide is weak, it has a lower potential than hypochlorous acid or hypobromous acid.
The oxidation capacity shows how many electrons are transferred at an oxidation or reduction reaction. The chlorine atom in chlorine dioxide has an oxidation number of +4. For this reason chlorine dioxide accepts 5 electrons when it is reduced to chloride. When we look at the molecular weight, chlorine dioxide contains 263 % ‘available chlorine’; this is more than 2,5 times the oxidation capacity of chlorine.
Table 2: the oxidation potentials of various oxidants.
|oxidant||oxidation strength||oxidation capacity|
|ozone (O3)||2,07||2 e-|
|hydrogen peroxide (H2O2)||1,78||2 e-|
|hypochlorous acid (HOCl)||1,49||2 e-|
|hypobromous acid (HOBr)||1,33||2 e-|
|chlorine dioxide (ClO2)||0,95||5 e-|
The following comparisons show what happens when chlorine dioxide reacts. First, chlorine dioxide takes up an electron and reduces to chlorite: