Study On Extract Processes Of The Biomass And Silica Of Rice Husks

Rice husks are the hard protecting coverings of rice,with certain peculiarities as tenacity, porosity , low density and coarse texture.our country is the greatest rice planting state of the world. The yields of the rice occupied much bigger ratio of the whole cereal yields. Its an productive, extensive cheap and regenerative resource. At present , our country still didn't form an utilize way which massive product and a great quantity consume of the rice husks.At the moment, the utilize of the rice husks have turned to the severance and use of their components from use as energy resources, the main components which can use of rice husks are biomass and silicon, the biomass include cellulose, hemicellulose and lignin. Meanwhile the cellulose and hemicellulose belong to polysaccharide. But much more research have concentrated to simplex component severance of the rice husks, however, this way caused a great deal of lose, so it didn't achieve total use of the biomass.This study takes cellulose, hemicellulose, lignin and silica of the rice husks as research subjects. Proposed technique paths which fit to industrial production and utilization; researched methods of extract and parameters condition. At first, pre-treat to rice husks, Through the determination of monofactory experiments and Scanning electron microscope (SEM) to research the effect of Polysaccharide content and structure by different Pre-treatments, that are alkali treatment and extrusion. Moreover, proposed a new method of alkali combined with extrusion pretreat rice husks, and used Polysaccharide content as indicator, adopted the analysis method of response surface methodology to determine the optimization conditions of the alkali combined with extrusion pretreatment to rice husks: extrusion, Screw speed 110rmp,Moisture content 40%,Barrel temperature 105℃;alkali,Solid-liquid ratio 1:20; the concentration of Sodium hydroxide 0.72mol/L; temperature 69.56℃;treatment time 34.59min. On conditions of the optimization, the Polysaccharide content of the rice husks can achieve 44.78%.Hemicellulose is easily dissolved, so extract hemicellulose from rice husks after pretreatment priority. Through comparison of five different extract liquors, draw a conclusion that Sodium hydroxide is the best extract liquor. Take the extraction rate of hemicellulose as indicator, adopted the analysis method of response surface methodology,the results are: The best extract condition of sodium hydroxide liquor extract hemicellulose from rice husks without pretreatment is Solid-liquid ratio 1:30; temperature 80℃;treatment time 4h; the concentration of Sodium hydroxide 1.02mol/L, On conditions of the optimization, the extraction rate of hemicellulose can achieve 42.74%; The best extract condition of sodium hydroxide liquor extract hemicellulose from rice husks after alkali treatment is Solid-liquid ratio 1:25; temperature 80℃; pre-treat time 4h; the concentration of Sium hydroxide 0.77mol/L, On conditions of the optimization, the extraction rate of hemicellulose can achieve 62.10%. The best extract condition of sodium hydroxide liquor extract hemicellulose from rice husks after extrusion treatment is Solid-liquid ratio 1:30; temperature 81℃;treatment time 3.5h; the concentration of Sodium hydroxide 0.89mol/L, On conditions of the optimization, the extract ratio of hemicellulose can achieve 72.68%. The best extract condition of sodium hydroxide liquor extract hemicellulose from rice husks after alkali combined extrusion treatment is Solid-liquid ratio 1:25; Temperature 75℃;Treatment time 3h; The concentration of Sodium hydroxide 0.79mol/L, On conditions of the optimization, the extraction rate of hemicellulose can achieve 80.59%. Through qualitative analysis of products by paper chromatography, chemical composition of the products are Arabinoxylan, Galactose, Glucose, small Xyloglucan. At the time of extraction hemicellulose by alkli,extracted silica from rice husks, the last production is white solide silica, by comparison of extraction rate of the silica from rice husks after different pretreatments, The highest extraction rate of silica from rice husks after alkali combined with extrusion pretreatment reached 75.68%.After pretreatment for rice husks, the content of cellulose is relatively low, and easier purified, so extract lignin first, adopt rice husks have been pretreated with alkali combined extrusion and after extracted hemicellulose. Use the methods of alkali separation, acid precipitation, and organic reagents to extract lignin. Through monofactory experiments proposed a new method of microwave combined with organic reagents to extract lignin, adopted the analysis method of response surface methodology to determine the optimization conditions are: Solid-liquid ratio 1:20; radiation power 750W; radiation time 41min; glycerine Mass fraction 90.7%,On conditions of the optimization, the extraction rate of the lignin can achieve 83.21%. By ultraviolet and infrared optical spectrum analysis of the product is mainly fit to official lignin. The optimization conditions of Acid extraction of the cellulose are: Solid-liquid ratio 1:15; Ethylic acid volume fraction 80%; Temperature 95℃; Time 25min, On conditions of the optimization, the extraction rate of cellulose can achieve 46.98%.