Ozonation as pretreatment method of wood for cellulose processing

Ozonation of wood is considered as a pretreatment of vegetable raw materials with the aim of a subsequent cellulose processing. The process of ozone consumption by aspen wood of various moisture content (MC) was investigated. The data on wood and cellulose transformations in the course of wood ozonation are presented. Yields of ozonized wood, water-insoluble wood ozonationproduct (WOP), water- soluble ozonation products, and cellulose were found. The lignin and cellulose content in WOP was determined. Both WOP and cellulose samples were investigated by the IR spectroscopy method.The degree of polymerization (DP) of cellulose obtained from ozonized wood is presented. It is shown that the destruction of wood by ozone includes lignin hemicelluloses and, partially, cellulose degradation. The yield, DP and supramolecular structure of cellulose obtained from WOP can be regulated by the variation of the initial MC of the substrate. It was found that the MC of 55% corresponds to the most efficient ozonation with theprominent wood structure transformation. A key role of water in biomass ozonation is emphasized. It is concluded that the ozonation of wood is controlled by diffusion. It is supposed that the wood destruction is caused by reactions of molecular ozone, as well as radical species generated in the course of ozone reactions with water present in the wood structure.