Research On Degradation Of Waste Wood Material By Three Kinds Of Wood-rot Fungus

Wood material is widely used for its light weight, high strength and other excellent properities. However, a large amount of waste wood materials are produced each year, imposing enormous pressure on the resources and the environment. How to handle with these waste materials has become a big challenge. Wood material is renewable resource, enabling its recycling use. The main component of wood is lignocelluloses, exploring the effective conversion utilization of lignocellulose is an important research direction to achieve sustainable development. Biological pretreatment of lignocelluloses which is energy-saving and environment friendly has received more and more attention. In this paper, three wood rot fungus which have degrading capability toward lignocellulose were chosen to decay the waste fiberboards and fiber, aiming to explore the degradation mechanism, and provide theoretical guidance for the efficient use of waste wood materials preliminarily.In this paper, the powder sample of Eucalyptus wood fiber board and wood fiber were degraded 12 weeks by three wood-rot fungus, including two white-rot fungus Corilus versicolor(C.v) and Irpex lacteus(I.i), and the brown-rot fungi Gloeophyllum trabeum(G.t). The loss of weight and the main components of sample after degradation, cellulose, hemicellulose and lignin were investigated by weighing and chemical analysis. X-ray diffraction(XRD) and Fourier transform infrared spectroscopy(FT-IR) were used to analyze the the change of crystalline region of cellulose and chemical structure after degradation, respectively. Change of thermostability was analyzed by thermogravimetry(TG). The results can be briefly listed as followed:(1) Compare the weight loss rate and main component loss rate of different samples degraded by the three wood-rot fungus with the sound samples, conclusion can be drew as followed: The white-rot fungi C.v shows strong lignocelluloses degrading ability; Treatment of wood fiberbood sample by I.i and G.t caused less degradation than in the wood fiber sample, indicating the lower biodegradation ability in fiberbood sample due to its complicated environment containing adhesive and formaldehyde. The white-rot fungi C.v and I.i both showd homogeneous degradation of lignin, cellulose and hemicellulose components. The brown-rot fungi G.t showed strong cellulose and hemicelluloses degrading ability, and less degradation of lignin.(2) After 12 weeks’ degradation by the three kind of fungus, X-ray diffraction intensity and crystallinity of the fiberboard and wood fiber samples both had varying degrees of decline. The brown-rot fungi G.t showed stronger ability to destroy the crystalline region of cellulose, than the other two white-rot fungus treatment. The two white-rot fungus posed small damage to the crystalline region of cellulose, mainly attacked lignin, hemicellulose and amorphous region of cellulose. The X-ray diffractograms profile of each degraded sample was similar with the sound sample, which means that the crystalline structure in the regions of cellulose had no significant change after degradation.(3) The overall trend and infrared absorption peak position in FTIR spectra of decayed and sound samples are basically the same. The characteristic absorption peak intensity of cellulose, hemicellulose and lignin of decayed samples decreased to varying degrees, indicating the three kinds of fungus all have the capacity to degrade cellulose, hemicellulose and lignin. The comparison result of degrading ability is C.v > I.i > G.t, verifying white-rot fungus’ intensive destruction toward lignin. Moreover, C.v also shows cellulose and hemicellulose degrading ability,The degrading ability was both strong in the two samples. Relatively, I.i showed weaker degradative capability. The fiberboard samples treated by the brown-rot fungi G.t showing that the characteristic absorption peak intensity characterization of cellulose and hemicellulose decreased significantly, indicating the cellulose and hemicellulose were damaged heavily, and lignin structure was also partially destroyed, but G.t showed weaker degradative capability in wood fiber samples.(4) Pyrolysis characteristics of fiberboard sample decayed by three kinds of fungus after 12 weeks had significant changes compared with the sound sample. The main features are the decreased the initial temperature of pyrolysis, the temperature at the maximum decomposition rate and lower heat stability, indicating that wood-rot fungus treatment can promote the pyrolysis reaction. Among the three fungus, the fiberboard sample treated by white-rot fungi C.v showed the lowest activation energy in each stage and poorest heat stability, indicating the strongest degradation ability of C.v.