Degradation of Structure of Populus tremula Wood during Delignification with Ozone. Thermal Analysis

Transformations of aspen wood under the impact of ozone were investigated by FTIR spectroscopy and simultaneous thermal analysis combined with mass spectrometry (TG/MS) of noncondensable products of pyrolysis. The TG/DTG curves of lignocellulosic materials (LCM) obtained at various values of specific absorption of ozone were analyzed. Simulation of DTG curves with Gaussian components was carried out. It is shown that the content of hemicellulose (HC) and lignin (LG) decreases and the content of cellulose increases under the impact of ozone in wood. FTIR spectroscopy data confirm the destruction of aromatic structures of LG and indicate the formation of oxygen-containing products of biomass ozonation as the specific absorption of ozone increases. Based on the TG/MS analysis of the LCM and the simulation results, the range of ozone consumption corresponding to the predominant destruction of LG and HC, and the range of ozone reactions with the ozonation products of the LCM were established. Degradation of the cellulose structure was found at high ozone consumptions.