Destruction of Lignin during the Ozonation of Pine Wood

Abstract

The consumption of ozone by pine wood with a water content of 7 to 85% is investigated. The specific ozone consumption and degree of ozone conversion during the ozonation of wood with different contents of water are determined. IR absorption spectra of ozonated lignocellulosic material (LCM) produced from wood are analyzed. Destruction of the lignin aromatic structure and the formation of carbonyl- and carboxyl-containing compounds are observed. The content of cellulose in a sample of ozonated LCM grows along with the specific ozone consumption. Products of the ozonolysis of lignin (glyoxylic, formic, and oxalic acids) form during ozonation of the wood, as determined via HPLC. It is shown that the oxidation of acids by ozone proceeds in the water phase of the sample. Based on the data for the destruction of lignin and the results from investigating the process of wood ozonation, it is concluded that the optimum content of water for wood treatment is 60–63%. It was shown that the destruction of lignin during wood ozonation proceeds via ozonolysis and with the participation of radicals formed in the reaction between ozone and water.