Interesting but complex question, which would deserve thorough and complete separate investigations ! Not only Cl species may produce a lot of different reactions, especially disproportionations, depending on the medium, as most of them are metastable, but the predominence of some species with regard to others is probably influenced by the pH and in general by the nature of the surface. Additionally, such a strong oxydizer (chlorate) probably produces many oxygenated species at the surface of the AC, which are prone to desorb during regeneration, thereby producing gas. In summary, I am afraid that there is no simple and straightforward answer to this question. One way should be to do the experiment in a TG apparatus coupled with MS.

Alain

Thank you Dr Celzard.  Yes more studies need to be conducted.  My own studies show the release of a pungent smelling gas.  That is why my suspicion that it could be either chlorine or chlorine dioxide. In chlor alkali plants, HCl is used with heat to reduce some of the chlorate into chlorine.  The quantity in my study was small, and hence I did not collect it for further analysis.    If it is Chlorine, it would have commercial value for chlor alkali plants.

I agree chlorate could be reduced by reaction with the carbon. Some of the gas could be CO2 and some could be ClO2. If you collect some of the gas in a iodide-in-water solution (KI) it will be easy to see if it is oxidizing.

If this test is positive you might like to make sure if the gas is ClO2 or Cl2. I can think of several reactions that can be used depending on your chemicals supply, but something along utilising that Cl2 but not ClO2 is absorbed in basic solution or that chlorine react with amines (glycine is a used to seperate them in many colorimetric sets).