Characterization of Pulp Ozonolysis Products, 1992 Environmental Conference Proceedings

Efforts to reduce the level of chlorinated organics discharged into the environment have sparked interest in ozone bleaching. Pulp ozonation by-products are not as well characterized as the by-products from traditional bleaching practices. It is important to know the composition of ozonation effluents so that their potential toxicity and treatability can be assessed. Information about bleaching mechanisms may also be obtained.

Gas chromatography mass spectrometry was used to determine the identities of low molecular weight pulp ozonolysis products. Derivatization of carbonyl compounds selectively provided information about carbonyl by-products. The effects of different pre-treatments on ozonation by-products were examined.

The small compounds in extracts of ozonated pulp are primarily fatty acids, short-chain and long-chain aliphatic acids and diacids. Only small amounts of monomeric lignin products are formed or survive ozonation. Oxalic and glyoxylic acid (and/or their methyl esters) probably arise from aromatic ring fragmentation. Glyoxylic acid (and/or its methyl ester) is the most abundant aldehyde produced. Derivatization techniques indicate that glyoxal is another important aldehyde. Carbonyl compounds present in small quantities in extracts of ozonated pulp appear to have polar precursors.