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Study On The Preparation Process Of Microcrystalline Cellulose From Salix Psammophila

Posted on:2015-05-25Degree:MasterType:Thesis
Country:ChinaCandidate:M X HuangFull Text:PDF
GTID:2181330431996490Subject:Pharmaceutical Engineering
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Salix psammophila is one of the desert shrubs widely planted in Chinese desertareas, which is a renewable biological resource. In addition, because salixpsammophila is a fast-growing shrubs, it must be regularly cut and rejuvenated toensure its growing best. After cutting, there are a large amount of branches produced.At present, the branches of salix psammophila are generally used as the raw materialsof particleboard, fiberboard and papermaking or converted into liquid materialsinstead of petrochemical resources by thermochemical treatments. But it is littleknown in preparing cellulose products by salix psammophila. Microcrystallinecellulose (MCC) is a kind of functional fiber polymeric material prepared bydegradation of the natural cellulose. It has a feature of non-toxic, harmless andenvironmental friendly. It has been widely applied in the fields of food,pharmaceuticals, chemicals and materials and so on, so that it has a huge marketprospect. In this paper, a reasonable technological process to produce themicrocrystalline cellulose from the salix psammophila has been set up. It is importantto effectively utilize the resources of salix psammophila, contribute to the economydevelopment of the desert region, promote the enthusiasm of people growing salixpsammophila, prevent wind storms and fasten sand in land, and improve theecosystem of the desert region.This paper mainly studied the preparation technology of salix psammophilamicrocrystalline cellulose. By discussing the pretreatment process of acid catalyticethanol for salix psammophila, the refining process of salix psammophila crude fiberand the hydrolysis process of refining salix psammophila cellulose, the preparationprocess of microcrystalline cellulose was optimized. And then, the physical andchemical properties of MCC were characterized, which laid a foundation for itsapplication.At first, the chemical composition of salix psammophila powder was determined,the result showed that the content of ash, benzene alcohol extractives, cellulose, total cellulose and lignin were4.528%,2.49%,36.95%,71.92%and24.77%, respectively.Then, the single factor test and the orthogonal test were used to study the effect ofeach factor on the pretreatment process of extraction of cellulose from salixpsammophila with acid-catalytic ethanol pulping, the optimized conditions werefound to be: the pulping temperature is206℃, the temperature holding time is55min,the concentration of ethanol is45%, the ratio of liquid to solid is10:1, theconcentration of acetic acid is1.3%. The cellulose product can be obtained under theoptimized conditions, the purity and yield were67.21%and48.14%, respectively.Then, the low pollution treatment process of two stages of sodium chlorite andalkaline hydrogen peroxide were used to treat salix psammophila crude cellulose, andthe conditions for each treatment process were optimized with the single factorexperiment. The results showed that the optimal conditions for sodium chloriterefining process were processing temperature of75℃, sodium chlorite concentrationof11g/L, processing time of60min, and under these conditions, the cellulose contentof salix psammophila was80.84%, the yield of first refined salix psammophilacellulose was80.23%. Moreover, the optimal conditions of refining process byalkaline hydrogen peroxide were reaction temperature of70℃, processing time of70min, hydrogen peroxide content of2%, sodium hydroxide content of4%, andunder these conditions, the cellulose content of salix psammophila was92.67%, theyield of second refined salix psammophila cellulose was78.23%.At the same time, the single factor experiment and the orthogonal experimentwere used to study some technological parameters of influence on the hydrolysisprocess of salix psammophila refining cellulose to obtain the optimized conditions.The optimized conditions were that the concentration of hydrochloric acid is12%,hydrolysis temperature is70℃and hydrolysis time is50min. Under these optimizedconditions, the yield of salix psammophila MCC was85.41%, the degree ofpolymerization (DP) was145.29.At last, the physical and chemical properties of homemade salix psammophilamicrocrystalline cellulose were tested and it was compared with both commerciallyavailable column chromatography microcrystalline cellulose and drug excipientsmicrocrystalline cellulose. The results tested on the homemade microcrystalline cellulose show that the cellulose content, pH, ash content,the whiteness, DP,crystallinity and particle size of the salix psammophila MCC are99.86%,5.8,0.1877%,89.3%,145.29,69.80%and19.83μm, respectively. And these indicators arein accord with the requirement of pharmaceutical excipient microcrystalline cellulose.Fourier transform infrared (FT-IR) spectroscopy indicates that acid hydrolysis doesnot affect the molecular structure of the microcrystalline cellulose. Scanning electronmicrograph analysis shows that the morphology of salix psammophila MCC isclavate shape that there are small holes on its rough surface. Thermogravimetricanalysis shows that the salix psammophila microcrystalline cellulose has a goodthermal stability, completely degradation temperature is358℃, the fastestthermo-weightlossness temperature is329℃, and the weight loss of salixpsammophila microcrystalline cellulose is82.83%.
Keywords/Search Tags:Salix psammophila, Microcrystalline cellulose, Acid-catalytic ethanolmethod, Sodium chlorite, Hydrogen peroxide
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