OCR Text |
Show incineration problems. First, they form a basis for estimating the minimum quantity of hydrogen atoms that must be present in order to destroy a given chlorinated aromatic compound to a certain level. Note that this is a conservative number since the primary mechanism for the destruction of organic molecules in combustion is undoubtedly through OH attack. Here we are considering the pockets of unburnt gas. Secondly, since we have measured the rate constant for H-atom attack on a number of chlorinated aromatics we are able to draw conclusions on how given initial distributions of cogeners will be effected by these processes. For this purpose we recall the most important conclusion, that is on a per chlorine atom basis the rate constants for displacement will increase with increasing degree of chlorination. Hexach10robenzene is the least stable of the chlorinated benzenes with a rate constant that is approximately at least a factor 15 larger than that for ch10robenzene. With this as a guide it is clear that if one begin with the most highly chlorinated aromatic, then under pyrolysis and given a certain concentration of hydrogen atom and sufficient reaction time one should be able to obtain the observed cogener distributions which are always peaked towards large numbers of ch10rines on the aromatic ring. The reverse cannot be true. A distribution that is peaked towards the low chlorine end cannot through dechlorination lead to a distribution that favors the highly chlorinated aromatic compounds. Third, since we also give rate constants for similar processes with related aromatics, it may be possible to use relative concentrations in effluents as a measure of severity of incineration. Although there is obviously the need for much further work, we note that the numbers on Tables I and II represent the beginnings of a data base on reactions involving chlorinated aromatics and related compounds. In 15 |