Re: basic info dioxin qn

[lshadoff@brazosport.cc.tx.us (Lewis A. Shadoff)]

>Hi,
>
>Does anyone know the temperature range between which dioxin is most likely to
>be formed?

It depends on the process.

In the laboratory the reaction of chlorine with aromatic compounds (like
unchlorinated dioxin) takes place at ambient temperature (slowly) in the
presence of a catalyst.  The reaction rate increases with temperature.
This is the way the first synthetic sample of 2,3,7,8-TCDD was made.

The chlorinated dioxins produced in the bleaching process for paper
production also takes place at low temperature (below the boiling point of
water).

In combustion (by definition a higher temperature process than those above)
chlorinated dioxins are formed if the building blocks are present (carbon,
chlorine, oxygen).  Above approximately 850 degrees centigrade they are
decomposed, however.  This dynamic process, then, is simultaneously
building and destroying dioxins (and other compounds as well).  What ends
up in the end depends on the combustion conditions and design of the
apparatus used to do the combustion.

I guess the answer is: any temperature below approximately 850 degrees
centigrade.



Lewis A. Shadoff BS, PhD, Lake Jackson, Texas