Mechanistic Studies on Ozonolysis of Lignin Wastewater Based on Ozonolysis of Lignin Model Compounds

Abstract

Reaction patheways of the ozonolysis of waste lignin discharged during the production of softwood pulp were examined through investigation of the ozonolysis of model compounds. The model compound consists of a 49: 51 (mol/mol) mixture of guaiacol and veratrole. The waste lignin in, water and the mixture of the model compounds in 50% aqueous dioxane were allowed to react with ozone at 30°C at pH 9. Aliquots from the reaction mixtures were withdrawn and determined for their absorbance at 280 nm, the formation of methoxyl, phenolic hydroxyl, muconic moieties, and also for the amounts of oxalic acid and its esters. The time profiles of the measured quantities showed good correlation between the waste lignin and its model compounds, except for the formation of methyl hydrogen oxalate from the model compounds.