Thermogravimetric Analysis And Kinetic Study Of Lignocellulose Modified By White Rot Fungus

Utilizing pyrolysis to convert lignocellulosic feedstocks including wood wastes and straw into bioenergy and bio-based products is the development direction of bio-refinery. Biological pretreatment can improve biomass pyrolysis by lignocellulose modification, but thermal decomposition characteristics and kinetics of modified lignocellulose are not completely clear. In this work, a modified three-parallel-reactions model was firstly proposed through investigating the effect of biological pretreatment with white-rot fungus Echinodontium taxodii 2538 on thermal decomposition characteristics of bamboo, which can systematically clarify the pyrolysis kinetics of bio-modified lignocellulose and the influence mechanism of biopretreatment. Furthermore, this modified model was applied to study the pyrolysis kinetics of wheat straw lignocellulose modified by white-rot fungus Pleurotus sp. CCD3.Firstly, thermogravimetric analysis was used to investigate the effect of biological pretreatment using Echinodontium taxodii 2538 on thermal decomposition characteristics of bamboo. The results indicated that E. taxodii 2538 can selectively degrade lignin fraction and decrease the extractives' negative effect on lignocellulose pyrolysis, thus effectively enhancing bamboo pyrolysis. Kinetic analysis using the three-parallel-reactions model showed that after pretreatment the maximum thermal decomposition rate of bamboo lignocellulose was greatly increased and this phenomenon was mainly related to a reduction in the activation energy of lignin and hemicellulose and the enrichment of cellulose fraction.Then, a modified three-parallel-reactions model was proposed based on the pyrolysis kinetics of bamboo lignin(EMAL) which was extracted using an enzymatic mild acidolysis method. Using this modified model, it was found that during the pretreatment process E. taxodii 2538 can transform the difficultly degradable component with high activation energy into the easily degradable component with low activation energy, thus making lignin easier to be pyrolyzed and consuming less energy. Compared to the original three-parallel-reactions model, this modified model can predict the degree of delignification during fungal pretreatment process more accurately and describe the real pyrolysis characteristics of lignocellulose.The modified three-parallel-reactions model was further applied to study the effect of pretreatment condition on the pyrolysis kinetics of wheat straw lignocellulose modified by Pleurotus sp. CCD3. The results demonstrated that this modified model had a wide applicability. From kinetic analysis of wheat straw lignocellulose, Pleurotus sp. CCD3 can also modify lignin and enrich cellulose to greatly enhance wheat straw pyrolysis. Besides, during fungal pretreatment process Mn2+ supplementation can further promote the delignification and lignin modification, improving thermochemical conversion efficiency of wheat straw lignocellulose.This study firstly proposed a modified three-parallel-reactions model to systematically clarify thermal decomposition characteristics and kinetics of lignocellulose modified by white-rot fungus, which will provide theoretical foundation for biological pretreatment prior to biomass pyrolysis.