Products formed during ozonation of organic compounds in aqueous solutions.

Abstract

Since halogenated organic compounds have been detected in drinking water, great interest has been directed toward the identification of products from chemical oxidation processes. To get water treatment processes which provide safe and delicious tap water, it is nessesary to have knowledge of the intermediate and end products formed during ozonation. It is also of great interest whether the products are potential toxic or precursors of other toxic compounds which could be produced if the ozonated effluent is subsequently chlorinated to provide residuals for disinfection. It is in general known that ozonation for a short or long time is effective for reducing mutagenicity, but uncomplete ozonation creates compounds which show more mutagenicity than the origin. Many researchers have found aromatic, phenolic, aliphatic mono and di-carboxylic acids, aldehydes and ketones to be present in the ozonation products. However, we do not know all the intermediate and end product formed during ozonation. This is due to the fact that ozone reaction is very complex because ozone itself is unstable, the concentratrion of product is too small for analysis and the number of products are too big. This report consists of four parts : 1) the two types of ozonation reactions ; (a) direct reactions of ozone with the organic compound and (b) free radical reactions of ozone which involve a hydroxyl free radical intermediate. 2) the oxidability of ozone ; (a) removal characteristic of CODCr and TOC and (b) comparison with the combination of UV radiation or nuclear radiation. 3) the reaction mechanisms of ozone with organic compounds. 4) the reaction products formed during ozonation and their mutagenicity directly or indirectly.