| Nowadays, with the escalating energy crisis, it is urgent to find the alternativeenergy for fuel. The conversion of lignocellulosic materials provides a sound solutionfor energy problems, thus has become an urgent task for the energy research. Butowing to lignocellulosic materials’ complex structure and high density, enzymolysis isinefficient, which restricts the conversion. The pretreatment is an indispensableprocedure for the conversion, but currently, it is relatively low in efficiency and costmuch. This paper was themed by developing a cost-lower and highly effectivepretreatment technology.First, the measuring conditions of hemicellulose and cellulose in bagasse andwood chips were optimized based on Wang Yuwang’s procedures on quantitativeanalysis of hemicellulose, cellulose and lignin in solid fermentation materials oflignocellulosic materials.The optimized measuring conditions of bagasse hemicellulose were changed asfollows: the measuring wavelength was670nm (originally660nm); the orcinconcentration was0.1%(originally0.2%); the hydrolyzed and colorized time at100℃for40min(originally20min) and measurement taken within50min after coloration.Under the optimized conditions, the evaluation of hemicellulose content proved thatits RSD was greatly decreased from4.85%to0.24%, which indicated that theprecision of this measuring had increased markedly. Because of the componentialdifference between wood chips and bagasse hemicellulose, the original measurementwas not feasible any longer. Then the3,5-Dinitrosalicylic acid method was used andthe corresponding measuring conditions were optimized as follows: the measuringwavelength was550nm, the volume ratio of DNS reagent to the testing solution was0.75:1, colorizing at100℃for5min and the standing time being60min. The precisiontest showed that the RSD was1.35%and the recovery test showed the averagerecovery rate was96.14%after analyzing the hemicellulose hydrolyzate using theoptimized measuring method.The cellulose measuring conditions were changed as follows: the wavelength was changed from625nm to620nm; the volume ratio of0.2%anthrone-sulfuric acidto the testing solution was changed from4:1to2:1, duration for hydrolysis andcoloration at100℃was10min andthe measurement was taken within40min. Underthe optimized conditions, the bagasse cellulose test showed its RSD decreased from5.47%to1.09%, which indicated the precision of the experiments was significantlyimproved.The wood chips were pretreated with A acid, sulphuric acid and peroxy-aceticacid, respectively. Then orthogonal tests were designed to evaluate the influence ofthe treatment time, solid-to-liquid ratio and mass fraction of acids on the content ofsolubilized reducing sugar under atmospheric pressure. According to the results, whenwood chips was pretreated by sulphuric acid at100℃for3h, the solid-to-liquid ratiowas1:15and the mass fraction was3%, there was the highest hemicellulose removalrate, which amounted to77.53%. The cellulose recovery were similar and were allabove90.00%.At the same time, we studied the influence of the concentration and the actingtime of B-alkali on the pretreatment under121℃with solid-to-liquid ratio of1:10. Wefound that when the ratio of B-alkali to wood chips mass was0.15:1and the reactiontime was15min treatment the pretreatment had the best results of26.44%hemicellulose solubilized,16.16%lignin removal and97.12%cellulose recovery.Pretreat the wood chips with sulphuric acid and B-alkali at their optimal reactionconditions alternately, the result showed that wood hemicellulose removal rate wassignificantly improved, amounting to91.31%. The lignin removal rate was more than20%, and the cellulose recovery rate was all above90.00%. |
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