Study On The Efficient Separation And Pulping Performance Of Bagasse Hemicellulose By Microwave Puffin

In this study,bagasse was used as raw materials,and ammonium bicarbonate was used as the expansion agent.Microwave expansion was used to loosed structure of fiber and improved hemicellulose extraction rate.Herein,the expansion rate,water retention value,porosity and surface morphology of bagasse before and after microwave expansion pretreatment were analyzed to prove the promotion effect of microwave expansion on bagasse hemicelluloses.At the same time,the lignin,extraction content and fiber crystallinity of bagasse after microwave expansion-microwave alkali extraction hemicelluloses were studied to determine the influence of other components extraction in bagasse.Through the calculation of H-factor and the establishment of delignification kinetic model in the process of bagasse soda anthraquinonoid pulping,the effect of microwave expansion pretreatment on the pulping effect of bagasse was investigated.The results of this study are as follows.Under the conditions as followed: ammonium bicarbonate dosage 8%,microwave power 900 W,expansion time 3 min and expansion temperature 90 ℃,the structure of bagasse was obviously loose,and some cell membranes were even broken.The expansion rate and water retention value of the raw materials were more than doubled.The yield of hemicellulose extracted by microwave alkali extraction was also about 20 percentage points higher than the untreated.The dissolution law of bagasse hemicellulose was studied.It was found that the dissolution activation energy of hemicellulose in the process of microwave expansion-microwave alkali extraction was only 9.26 KJ/mol,which was 22.42 KJ/mol lower than that of untreated hemicellulose(31.68 KJ/mol),and it further proved the promotion effect of microwave expansion on hemicellulose dissolution.The analysis of lignin,extract and ash content in bagasse materials after microwave expansion-microwave alkali extraction of hemicellulose showed that microwave expansion treatment also had a positive effect on the dissolution of lignin,extract and ash content in bagasse.Under the conditions of ammonium bicarbonate dosage of 8%,microwave power of 900 W,expansion time of 3 min and expansion temperature of 90 °C,the removal rate of bagasse lignin after microwave alkali extraction of hemicellulose was more than 60%.The analysis of BET and XRD of bagasse before and after microwave expansion-microwave alkali extraction showed that the small pores porosity of the fibers was decreased after microwave expansion,and the porosity of mesoporous and macrospores were increased.The crystallinity of the fibers was also increased by nearly 46% due to the dissolution of hemicellulose,lignin.The bagasse materials after microwave expansion-microwave alkali extraction of hemicellulose were subjected to caustic soda anthraquinonoid pulping.It was found that the screened pulp yield was more than 60% under the conditions of digestion temperature 130°C and holding time 30 min.The purpose of low digestion temperature and high screened pulp yield was achieved.At the same time,the delignification kinetic model and the calculation of H-factor were further found that microwave expansionmicrowave alkali treatment could directly make the bagasse pulping process enter a large number of delignification stages,which was provided theoretical guidance for the efficient pulping of bagasse raw materials.