Extraction Of Hemicellulose From Corn Straw

In addition to cellulose,hemicellulose is the most abundant and most widely in source of renewable biomass resources.As a large agricultural country,the amount of agriculture waste resources is huge in china every year.But this huge resource,only the cellulose and lignin have been widely developed and applied,and have achieved the standardization of industrial production.While the hemicellulose,which content second only to cellulose,even if the researchers have researched and developed of it many,but there also are many difficulties of application due to its special structure.So how effective separate the hemicellulose from biomass has become a hot topic.Hemicellulose The effective development and utilization of hemicellulose,not only can achieve the comprehensive application of agricultural waste,improve resource utilization,maximize its practical value,but also it has played an important role in protecting environment.Development and application of hemicellulose has great practical significance and economic benefits to promote economic and social development.The main purpose of this paper is to extract hemicellulose from corn straw.We studied the conditions of hydrothermal and alkaline respectively by single factor and orthogonal test analysis.Then using the alkali extraction to treat the residue that untreated completely in hydrothermal method.To combine the two methods,at the same time improve the extraction rate as much as possible,reduce costs and protect the environment,maximize resource utilization.(1)Hydrothermal method has its particular advantages.It only uses water as the solvent,without consuming any chemicals.In addition,the reaction system only has a weak acidic because of a small amount of acetyl hydrolysis produces a small amount of acetic acid,so there is a little corrosion of equipment.In this paper,using the single factor analysis and orthogonal experiment to determine the optimum conditions for the hydrothermal method.And the optimum conditions are as follows: the extraction temperature 170 ?,holding time of 30 min,solid-liquid ratio of 1:15,respectively.Under these conditions,the extraction rate of hemicellulose is 32.21%.(2)Alkali can swell cellulose and break the chemical link between the cellulose and hemicellulose,and destroy the ester bond between lignin and hemicellulose.And we can achieve the purpose of separation and extraction of hemicellulose without unduly destroy the structure of hemicellulose.By analyzing and comparing,we choose the NaOH as the extraction agent in this paper.By single factor and orthogonal test analysis to determine the optimum alkaline extraction conditions were as follows: alkali concentration 10%,temperature 75 ?,solid-liquid ratio of 1:20,respectively.Under these conditions,the extraction rate of hemicellulose is 45.18%.(3)To combine the two methods after determining the best conditions for alkaline extraction and hydrothermal.Using alkaline treat the remaining residue from hydrothermal.Hemicellulose extraction rate is 37.35%.The final hemicellulose overall yield is 69.56%.