Acidified Chlorine vs. Acidified Chlorine Dioxide

The paper compares the properties and efficacy of acidified chlorine and acidified chlorine dioxide in treating laboratory animal drinking water. Chlorine has a higher oxidation potential than chlorine dioxide, making it more reactive with a wider range of organic structures. In contrast, chlorine dioxide reacts more selectively with certain sulfur, nitrogen, and other oxidizable structures.

Oxidation Capacity: Chlorine dioxide has a higher oxidation capacity, donating 5 electrons to oxidation compared to chlorine’s 2 electrons. This makes chlorine dioxide effective at lower concentrations (typically 4-20 times less) than chlorine.

Efficacy in Controlling Pathogens and Biofilm: Chlorine dioxide demonstrates better efficacy in controlling oo-cysts (e.g., giardia and cryptosporidium) and biofilm in water systems, making it preferred over chlorine in such cases. Chlorine dioxide effectively controls bacterial levels in both concentrate and permeate in pure water systems, while chlorine has limited efficacy in killing and removing bacterial biofilms. The changeover to chlorine dioxide treatment in biofilm-containing systems may result in an initial spike in suspended bacterial loads as chlorine dioxide strips biofilm from the system walls.

Materials Compatibility: Chlorine dioxide does not corrode stainless steel (e.g., 304L) even in the presence of chloride, while chlorine can cause corrosion in crevices of stainless steel at low concentrations.

Disinfection Byproducts (DBPs): Chlorine forms disinfection byproducts (DBPs), including potentially carcinogenic compounds, when reacting with organic compounds. Chlorine dioxide produces fewer DBPs and does not chlorinate organic compounds.

Interaction with Antibiotics: Chlorine dioxide reacts differently with antibiotics compared to chlorine, resulting in the formation of different byproducts and preserving antibacterial activity.

Animal and Human Acceptance: Animal acceptance studies suggest that mice avoid chlorine-treated spaces but exhibit no behavioral changes with chlorine dioxide. Human acceptance testing shows no taste or odor difference between water treated with chlorine dioxide (up to 8 ppm) and untreated water, while chlorine-treated water can have a distinct taste and odor.

This summary provides a comprehensive comparison of acidified chlorine and chlorine dioxide, highlighting the benefits of chlorine dioxide in various applications.