Engineering Science Paper

Study on Wood Color Improving Treatment of Plantation Eucalyptus Urophylla

Engineering Science — Sat, 25 May 2013 10:54:18 +0000

The study of this dissertation is mainly pointed to the problems of wood color met in the manufacturing of wood clothes racks made of plantation Eucalyptus urophylla wood,which will made a bad visual effect after translucent painting.These wood color problems mainly contain the color difference between sapwood and heartwood,inhomogenous color,dim color and lustre,etc.In order to study how to improve the visual effect of the wood color of plantation Eucalyptus urophylla,bleaching,coloring and other methods were adopted in the experiments of wood color treatment.And the results indicate that:The color difference between sapwood and heartwood,inhomogenous color, dim color and luster,and other color defects on the plantation Eucalyptus urophylla wood could be cleared,and the color of treated wood could be improved into well-proportioned white by bleaching treatment.With chemical coloring treatment,it not only could cover up the wood color defects,but also could make some good-looking color show on the wood surface.Besides,with the treatment of dyeing solely,dyeing after bleaching and the integrative color treatment,it also had some color improving effects in a certain extent,but the effects were not better,and the treatment prescriptions and techniques were more elaborate than that of the bleaching and chemical coloring treatment.In all kinds of decolourant prescriptions adopted in the experiment,the oxidation prescriptions had better and more obvious bleaching effects than the deoxidize prescriptions.And the peroxide prescriptions had better bleaching effects than other oxidation bleaching prescriptions.The hydrogen peroxide prescriptions had better bleaching effects than other peroxide prescriptions.The prescriptions with alkali or alkaline salts as active adjuvant had better bleaching effects than other hydrogen peroxide prescriptions,and when sodium hydroxide or potassium hydroxide as active adjuvant,wood color treatments could have the best and most obvious bleaching effects.For the hydrogen peroxide prescriptions with sodium hydroxide or potassium hydroxide,the formulations and technics parameters affected greatly the bleaching effects.In technics factors,the effect of treatment temperature was maximal;the effect of treatment time was secondary;and the effect of liquor ratio was most unconspicuous.And in the formulation factors,the effect of dosage of sodium hydroxide was maximal;dosage of sodium silicate was secondary;and concentration of hydrogen peroxide was minimal.The concentration of hydrogen peroxide and treatment temperature effected greater towards bleaching rate and effected weaker towards bleaching quality.The better hydrogen peroxide bleaching formulation and technics were that:concentration of hydrogen peroxide was 40, dosage of sodium hydroxide was 5g/L,dosage of sodium silicate was 10ml/L; treatment temperature was room temperature,treatment time was 2h.When the coloring formulation,chief chemical and adjuvant of which were respectively hydrogen peroxide and chemical X,was adopted in the wood color improving treatment experiment,it not only could cover up the wood color defects,but also could make Eucalyptus urophylla wood show some good-looking color on the wood surface,which was very similar with Schima superba wood color.The treatment formulation and technics were that: concentration of hydrogen peroxide was 10%,dosage of chemical X was 40g/L; treatment temperature was room temperature,treatment time was 0.5h.When the coloring formulation,chief chemical and adjuvant of which were respectively oxalic acid and chemical Y,was adopted in the wood color improving treatment experiment,it not only could cover up the wood color defects,but also could make Eucalyptus urophylla wood show some good-looking color on the wood surface,which was very similar with mahogany wood color.The treatment formulation and technics were that:concentration of oxalic acid was 2%,dosage of chemical Y was 10g/L;treatment temperature was 90℃,treatment time was 0.5h.

Study on Displacement Digester Systerms (DDS) Cooking with the Mixture of Eucalyptus and Bamboo

Engineering Science — Sat, 25 May 2013 10:22:24 +0000

The process conditions of displacemented cooking with the mixture of eucalyptus and bamboo was optimized by single-factor experiment. The optimal process conditions of displacemented cooking were: the dosage ratio of eucalyptus: bamboo was 3:2, pretreatment time was 60min （total time of the three pretreatment stages）, the charge of alkali was 17% （calculated as Na₂O）, 25% Cooking the Sulfidity （calculated as Na₂O）, the heating up time was 160min, the maximum temperature was 168℃. The fiber morphology of pulp indicated that the average length, width, the ratio of fiber length, fiber width and fiber length distribution of mixed pulp were better than which of the eucalyptus pulp or bamboo pulp. The fiber length distribution ranged between 0.20 and 1.20mm, mainly ranged between 0.50 and 0.80mm. The fiber width distribution ranged between 8.0 and 32.0μm, mainly ranged between 8.0 and 16.0μm.The law of delignification and reaction process of displacemented cooking with the mixture of eucalyptus and bamboo were studied. The results indicated that the reaction process of delignification included three stages during cooking, namely the initial stage of delignification, the main stage of delignification and the stage of residual lignin removal. A part of lignin was removed in the initial stage of delignification, the removal rate was 27.54%. The removal rate of the main stage of delignification was64.66%, and the removal rate of the stage of residual lignin removal was 3.97%.The reaction dynamic of the displacemented cooking with the mixture of eucalyptus and bamboo was studied. It was found that the lignin concentration of the main stage of delignification and the stage of residual lignin removal was the first grade reaction to the reaction of delignification, and the activation energy of the two stages were 51.609 kJ/ mol and 64.955 U/mol respectively.The concentration of NaOH had great impact on the final extent of delignification. In the main stage of delignification, the grade of concentration of NaOH to the reaction of delignification was 0.89, and in the stage of residual lignin removal was 1.49. The concentration of Sulfide also had great impact on the two stages. In the main stage of delignification, the grade was 0.43, and in the stage of residual lignin removal was 0.86. Finally, the dynamic model of the displacement cooking with the mixture of eucalyptus and bamboo was determined as follow:The main stage of delignification: -dL/dt=A₁e^-6208/T[OH^-]^0.89[S^*]^0.43The stage of residual lignin removal:-dL/dt=A₂e^-7813/T[OH^-]^1.49[S^*]^0.86

Study on the Process and Mechanism of High Boiling Solvent Pulping of Bagasse

Engineering Science — Sat, 25 May 2013 09:50:21 +0000

Solvent puping is available way that can separate fiber,lignin,sugars, and other components from raw materials to achieve cleaner production,.Ethanol and methanol as the representative of the lower aliphatic alcohol (boiling point less than 100℃) is the most common organic solvents of solvent pulping, due to these lower aliphatic alcohol solvent with a low boiling point, highly volatile and flammable properties, high pressure caused easily during ethanol pulping, high security requirements is needed for the process of pulping equipment and operation, otherwise the solvent recovery is very difficult. For this reason, 1,4 -butanediol is chose as solvent of pulping for this study, and explore the process and mechanism during HBS(1,4 – butanediol) pulping of bagasse , Research including: process conditions optimization of pulping and pulp washing , cooking reaction course, kinetics of deligniflcation and carbohydrate degradation. The results are as following:1、The HBS (1,4 – butanediol) pulping without acid catalyst showed that the temperature had greatest effect on cooking. The result of bagasse HBS pulping show that the appropriate conditions for the preparation of lignin and pulp: 1,4 – butanediol solvent concentration of 60 %, cooking temperature of 190℃, time at temperature of 90 min, liquid ratio of 1:6.2、The objectives of rearch were to investigate the effect of catalysts on HBS pulping,the results showed that: Catalyst (formic acid, acetic acid, citric acid) used in HBS pulping were able to increase the removal of lignin ,and reduce cooking temperatures and cooking time during HBS pulping, among them citric acid had the best obvious effects on the delignification ,however catalyst used in HBS pulping decrease the physical strength of the paper. The infrared analysis of the lignin showed that acid catalyst had little effect on the structure of lignin.3、HBS pulp washing research shows that the stage and solvent content of washing had greatest effect on pulp washing . After two stages of 1,4 -butanediol washing most of lignin adsorbed on the fiber surface were removed. SEM analysis of fiber surface showed that: the traditional washing used water in room temperature was not efficent for HBS pulp washing ,two stages of 1,4 -butanediol washing were able to remove lignin adsorbed on the fiber surface. Finally ,we can achieve the 1,4 – butanediol pulp washing appropriate conditions : washing solvent content greater than 60%, time at temperatue of 30 min, temperature of 80℃, liquid ratio of 1:6, washing stages of 2.4、Study of HBS cooking couse without catalyst show that pH of pulping system had great effect on delignification and carbohydrate degradation, reaction rate is fast at the previous stage and become slowly at later stage . The kinetics analysis of the cooking process showed that the delignification reaction follow two pseudo first-order kinetics,bulk and final phases., and the activation energy was 98.6 kJ/mol and 152.3kJ/mol ,respectively; The carbohydrate degradation of cooking process are all in the pseudo fist order ,the bulk an the residual phases activation energy were 117.4kJ/mol and 125.9kJ /mol, respectively.This paper study on the factor of cooking and washing duiring HBS pulping ,and optimize the appropriate conditions for the preparation of lignin and pulp ,and show reaction rules of physical chemistry, in order to provide the basic data for cleaner production of pulp and paper making and resource utilization of agricultural and forestry waste materials.

Study on Biodegradation of Hydrogen Peroxide in Recycled Pulp Bleaching

Engineering Science — Sat, 25 May 2013 09:18:24 +0000

Aerobic microbes,which growed in slime pulp will produce catalase degrading H₂O₂,It reduced bleaching efficiency of hydrogen peroxide.In this paper,the effect of biology enzyme on hydrogen peroxide bleaching of the waste-paper pulp was studied,mainly including screening of catalase-producing strains,partical identification of strains,analysis of enzymatic characteristic, application experiment of catalase-producing bacteria degrading H₂O₂ and effect of catalase on hydrogen peroxide bleaching of the waste-paper pulp.Three high-yield catalase strains were isolated from slime pulp.One of them was relatively high yield of the fungus C-1,the preliminary identification belonged to Aspergillus niger;another two were bacteria B-5 and D-6,the D-6 strains belonged to Bacillus subtilis,the B-5 strains belonged to Bacillus,Its 16S rDNA sequence was closely related to Bacillus subtilis Fs32b,Bacillus subtilis CICC10028,et al.with similarity of 99%.The highest enzyme producing strain was B.subtilis.B-5,the amount of enzyme was 1023.3 IU/ml.The results showed that the optimal growth conditions of strain B-5 were:Temperature: 42℃;pH:8.5;NaCl:4.0%.and the optimal enzyme production conditions were: Time:48h;Temperature:42℃;pH:8.0;NaCl:3.0～5.0%. The study of the enzyme properties of catalase showed that the optimum temperature and pH were 45℃and 9.0 respectively,the enzyme had a better stability below 60℃;and from 6.0 to 9.0 of pH;Fe³⁺,Mn²⁺could weakly activate enzyme ability,and Ca²⁺,Fe²⁺could strongly inhibit enzyme ability.The biodegradation experiment showed that B.subtilis.B-5 had exerted certain influence on hydrogen peroxide bleaching of recycled pulp,brightness of peroxide bleached pulps and the concentration of residual H₂O₂ decreased by 0.92%ISO and 0.58%respectively.It was also showed that the rough enzyme solution of catalase which produced by B.subtilis.B-5 had a great impact on hydrogen peroxide bleaching,brightness of peroxide bleached pulps and the concentration of residual H₂O₂ decreased by 1.36%ISO and 1.069%.Through studying the influences of catalase on recycled pulp bleaching under different conditions,it was found that the conditions which effected the bleaching results greatly were:pulp consistency 10%;H₂O₂ 2.0%;NaOH 0.3%; Na₂SiO₃ 3.0%;MgSO₄ 0.5%;EDTA:0.15%;enzyme charge 8.37 IU/g pulp; 60℃;1h.The brightness of bleached pulps and residual H₂O₂ after chelating decreased more obviously than that of without chelating agents.It showed that the chelating agent controlled the decomposition of hydrogen peroxide by the metal ions and restrained the activity of CAT.

Study on Agglomeration-Magnetic Removing Stickies of Mixed Office Waste Paper

Engineering Science — Sat, 25 May 2013 08:46:25 +0000

Mixed office waste paper has become the growth point in the secondary fiber recycling.However,the contaminations of non-contact printing inks and stickies in the fibers usually causes trouble in the recovering process.In the this paper,the octadecanol was used,by adding magnetite,to agglomerate the ink and stickies in waste paper,and these contaminations was removed by magnetic separation.Through using the single factor method experiment,the various factors on the agglomeration-magnetic separation process had been discussed. And by the use of pressure sensitive adhesive model,the effect of agglomeration on the stickies,and also the basic tenets of agglomeration by SEM,FTIR analysis had been studied.The results show that:Magnetite particle size,as well as the stirring speed of the agglomerating process are very effective at agglomertating inks.Best agglomeration process parameters for mixed the office waste paper is that:the agglomeration temperature is 70℃,and octadecanol content is 2%,magnetite particle size is mesh of 60-80,with the stirring speed of 800 r/min,and agglomerating 60 min, during the agglomeration pulp concentration is 4%,centrifugal magnetic separation concentration is 1%,by centrifugaling 30 min.As a result,99%ink removal rate has been obtained,with less than 0.18%of DCS in the deinked pulp.The presence of sodium hydroxide has a negative role in the process,and agglomeration-magnetic separation method is a neutral approach,eliminating the degradation of fiber caused by sodium,as well as environmental problems.FTIR spectra shows that the absorption strength of the ink and adhesive in deinked pulp after agglomeration-magnetic separation,decreases significantly. Octadecanol has strong wetting action on inks and stickies,as well as the images of SEM showes that through “liquid bridge” role,octadecanol connects inks and stickies together,forming agglomerates,similar to balls,in the “enbedding” state.

Biodiesel Production Based on Cotton Seed Oil Catalyzed by Lipase from A. Niger Li-38

Engineering Science — Sat, 25 May 2013 08:14:30 +0000

To prepare the biocatalyst for biodiesel production, the strain which could produce lipase was screened and the characteristics of lipase were investigated. The catalyzing system was built to converse the cotton seed oil to biodiesel when the immobilized lipase was as catalyst. The results were following:A new strain, Li-38 from Xinjiang was screened which could express lipase massively. The strain of Li-38 is a member of Aspergillus niger after identified by morphology and 18SrDNA gene sequenes, and named Aspergillus niger Li-38（A. niger Li-38）.The study of fermentation characteristic indicated that the cell growth of A. niger and lipase production were partially coupled. The study of fermentation characteristic indicated that the optimal cultivation parameters for temperature and pH were determined as 45℃and 5.5, respectively; the optimized nitrogen source was 1% （w/v） of （NH4）2SO4, 3% （w/v） of peptone and carbon source was 1.5% （w/v） of rap oil; the concentration of metal ions were 0.01 % （w/v） of K2HPO4, 0.01 % （w/v） of MgS04·7H2O, 0.01% （w/v）of CaCl₂, 0.01% （w/v） of NaCl₂ respectively. Under the optimized conditions, activity of lipase reached the highest yield of 84.9 U·ml^-1.Three mutant methods including UV radiating, DES treatment and microwave radiating were applied in the treatment to spore and protoplast of A. niger Li-38. The results showed that the effect of the compound treatment of UV radiating and DES on them was better. The optimal mutant parameters for spore of A. niger Li-38 were determined as the concentration of 1%DES+UV,the corresponding mutant times were 20min + 20s,15min + 30s,10min + 40s,10min + 50s,5min + 60s respectively. Preparation conditions for protoplast were optimized, which were determined as 1% of lywallzyme, 0.5% of snail enzyme, 1% of cellulose, and treatment time 40min. The optimal mutant parameters for protoplast of A. niger Li-38 were determined as the concentration of 0.2%DES+UV,the corresponding mutant times were 30min+10s,20min +20s,15min + 30s,10min +40s respectively. One mutant strain whose activity of lipase was improved 38% reached 125.36 U·ml^-1. The genetic stability of mutant strain MLi-38 was good.Research about the characteristic of lipase showed the following results. The optimal reaction temperature and pH were 50℃and 5.5 respectively, and the enzyme was relatively stable under 70℃and pH 5.5⁵.0. In all of the metal ions tested, Na+、Mg²⁺、Ca²⁺and K⁺ have activation effect, while Fe²⁺、Zn²⁺ and Cu²⁺ have inhibition effect on the enzyme and Mn²⁺ almost has no effect. When cotton seed was as substrate, the activation energy and inactivation energy of the catalyzing reaction of lipase were 9.8 kJ·mol– 1 and 87.975 kJ·mol– 1. The study also displayed that Km and Vmax were 9.706 mmol·L^-1 and 12.11μmol·L^-1·min^-1.Chitosan was as immobilizing material for the immobilized lipase and the optimal parameters for immobilization were determined that the concentration of glutaraldehyde was 0.015% and the cross-linking time was 50min. The optimal reaction parameters for biodiesel production in the transesterification of cotton seed oil and methanol were determined that t-butyl alcohol was as the reaction media, the water concentration was 0.6%, the reaction temperature was 8%, the ratio of methanol and fatty acid was 0.3. Batch-addition of methanol technology was adopted, which methanol was added in 0 h, 7 h and 16 h. After reaction for 28h, the highest rate of transesterification reached 89.1%. The research for the characteristics of cross-linked immobilized lipase showed that its storage stability was better. After 12d at room temperature, the activity of lipase also retained 80% and 30 d, 46.8%. The immobilized lipase was stable at 30-70℃, pH 5.5-6.5. After immobilized lipase utilized for seven times, the ratio of transesterification was over 80%.

The Research of Biodiesel Preparation and Its Emergy Analysis

Engineering Science — Sat, 25 May 2013 07:42:34 +0000

With soybean oil as raw material, three technics of biodiesel preparation, namely supercritical methonal technics, solid acid technics and solid base technics, were explored respectively. And on the basis of theory of emergy analysis, comprehensive evaluation of three technics, which including the economic and environmental benefits evaluation, were conducted. The results were obtained as follows:1. The effects of molar ratio of methanol to soybean oil, temperature, pressure, reaction time, water contents and acid values of the oil on the yields of biodiesel and glycerol were investigated in biodiesel production by supercritical technics. The results showed that the effects of molar ratio of methanol to soybean oil, temperature, pressure, reaction time on the yields of biodiesel and glycerol were remarkable, and the effects of water contents and acid values of the oil on the yields of biodiesel and glycerol were not remarkable. And the highest temperature and water content shouldn’t exceed 280℃and 10% respectively. Through orthogonal experiments, the optimal conditions were obtained when molar ratio of methanol to vegetable oil was 30:1, operation pressure was 20 MPa, reaction temperature was 280℃and reaction time was 60 min, under which the yields of biodiesel and glycerol could reach 89.14% and 88.73%, respectively.2. A new type of solid acid was prepared by calcination of titanium sulphate doped with lanthanum oxide. Preparation of biodiesel was studied from soybean oil and methanol catalyzed by the above solid acids, The experiment showed that the optimal conditions were obtained when catalyst amount was 3wt% (catalyst/oil), molar ratio of methanol to vegetable oil was 12:1, reaction temperature was 150℃and reaction time was 5h, under which the yields of biodiesel could reach above 90%. The catalyst also showed its activity for esterification. Therefore, it could be used for biodiesel production from many kinds of raw material. The catalysts could also be reused after some treatment.3. Transesterification of soybean oil and methanol to produce biodiesel were investigated using CaO/NaY as catalyst. The results showed that molar ratio of methanol to soybean oil was 9:1, catalyst amount was 3%(catalyst/oil), reaction temperature was 65℃and reaction time was 3h, under which yield of biodiesel could reach about 95%. The results also indicated that the CaO/NaY catalyst was more tolerant to free fatty acid and water and its activity was still high when acid value and water content were 4mgKOH/g and 1.5%, respectively.4. After emergy analysis of Three technics , it can be drawn that the ratio of unrenew resource to overall invested emergy in supercritical technics, solid acid technics and solid base technics for biodiesel production were less than the traditional liquid base technics in terms of pressure on the environment. The overall system transform ratioes of every technics were all relatively low, among which that of liquid base technology was lowest, which is 3.48E-01sej/t. The net emergy yield ratioes of supercritical technics, solid acid technics and solid base technics were higher than that of liquid base technics. Moreover, the emergy investment ratioes of supercritical technics, solid acid technics and solid base technics were higher than that of liquid base technics, meanwhile, supercritical technics, solid acid technics and solid base technics were lower than that of liquid base technics, which suggested that the former three technics were relatively low at present. There were good sustainable development for all four technics.

Study on Extraction and Physical-chemical Properties of Pectin from Sunflower Head

Engineering Science — Sat, 25 May 2013 07:10:37 +0000

Pectin is the most important soluble dietary fiber in sunflower head, the production of pectin in China is still lagging, and the technology of extraction which costs lower and products higher is not perfects. In order to improve the yield and quality of pectin, and actualize the reuse of depectin pomace, we compared the effects of tradition acid and microwave-assisted method extraction on pectin yield and quality, adopts technical of active carbon and resin decolor the solution of pectin, Finally, gained the pectin with alcohol diposition. The physical-chemical properties of the sunflower head pectin were also investigated. The result shows:(1) The materias were ground by a mill to pass a 60-mesh size screen、destroying enzyme inboiling water about 3min and washed with water at 75℃and stirred slowly for 15 min at a solid: Liquid ratio of 1:20 ahead of pectin extraction, will gain a high pectin yield, the pectin has little impurity and has good colour and luster.(2) The tests were optimized through good single factor selecting and Response Surface Methodology (Central Composite Rotatable Design). The predicted values were obtained by equation very well.The conventional extraction optimal conditions is temperature 89℃, action time 100 min, pH 3.4 and rate of solid/liquid 1:25; and the MAE optimal conditions is microwave power 450 W, action time 6.5 min, pH 3.4 and rate of solid/liquid 1:20, were determined by response surface methodology (RSM). Application of MAE in the extraction from dried sunflower heads dramatically reduced extraction time compared with conventional extraction.(3) Through single factor analysis method contrast the decoloration effect of carbon and resin. It shows that the effect of decoloration with resin is better than active carbon, and the method of decoloration with resin is suitable for industrial production. We can get the conclusion by good single factor selecting experiment: pH is 4, temperature at normal, velocity is 3.6 BV/h. This method can take off 84.3% of the pigment.(4) The influence of alcohol concentrations, concentration ratio, washing times on the efficiency of inspissation were studied in good single factor selecting and orthogonal experiment design. Pectin purity and gain ratio were used as index of the precipitated process. The results showed that concentrate multiple 4, alcohol concentration 70%; pH is 1.5, the optimal purity of pectin 81.65%.(5) Degree of esterification, moisture, ash, pH, galacturonic acid content were determined by GB standard, and all the parameters of sunflower head pectin was found to be in accord with the specification of GB. The solubility, viscosity, hot-stability and gel properties were compared sunflower head pectin with low methoxyl pectin.

Studies on L-Arginine Fermentation Conditions

Engineering Science — Sat, 25 May 2013 06:38:42 +0000

In this paper, the optimal seed medium, the best fermentation medium in flask-shaking and the batch fermentation process in 5-liter fermentor and the analysis of dynamic were investigated for L-arginine production with recombinant Escherichia coli LGE35（Thr^-, Met^-, Kan⁺）. The results are as follows:[1] The genetic markers were tested for E.coli LGE35（Thr^-, Met^-, Kan⁺）. The results showed that the genetic markers were not lost. The optimal seed medium was optimized by one-variable-at-a-time and orthogonal experiment methods. The optimum seed medium composition was found to be: sucrose 20g/L, beef extract 50g/L, peptone 20g/L, L-methionine 0.05g/L, L-threonine 0.05g/L,kanamycin 0.1g/L, calcium carbonate 20g/L.[2] Based on the one-variable-at-a-time experiment of fermentation medium, three main significant factors of the sucrose, ammonium sulfate and yeast extract powder which affect the flask-shaking batch fermentation production of L-arginine secreted by recombinant E.coli LGE35 were screened by the Plackett-Burman design. The optimal level of these three significant factors and their interactions were studied by response surface methodology. The polynomial regression model was established and the optimum medium composition was determined as follows: sucrose 71g/L,ammonium sulfate 31g/L,yeast extract powder 14g/L, MgSO₄·7H₂O 1g/L, K₂HPO₄ 3g/L, L-methionine 0.15g/L, L-threonine 0.1g/L, kanamycin 0.05g/L, FeSO₄ 0.01g/L,MnSO₄ 0.01g/L,VB1 0.01g/L. The optimum fermentation condition was studied. The results showed that: temperature 30℃, pH7.0, inoculum 8%, flask-shaking speed 240 r/min.. Under optimum conditions, after the strain E.coli LGE35 was cultured 96 hours, it can be produced 16.04g/L of L-arginine which increased about 32.78% more than before.[3] Based on the flask-shaking batch fermentation condition, the batch fermentation was investigated with strain E. coli LGE35 in 5-liter fermentor. The L-arginine batch fermentation kinetics was studied based on the experimental data from the batch fermentation of 5-liter fermentor. Three kinetic models were constructed which could reflect the regularity of growth, product formation and substrate consumption in the process of batch fermentation.

The Production of Functional Xylooligosaccharides from Cotton Seed Husk by Enzyme System

Engineering Science — Sat, 25 May 2013 06:06:43 +0000

The functional oligosaccharides have become a kind of important functional foods’ base materials in recent years.Since they have some specific physiological functions ,such as promoting the multiplication of Bifidobacteria in intestines, keeping a good healthy for peoples, the functional oligosaccharides have been attached important to by the researchers all over the world. A xylooligosaccharide is composed of 2-7 xylose. The link between the molecules isβ-1,4 xylosidate band. It can be prepared byβ-xylanase reaction with cotton seed hull, corn cob or rapeseed hull. It’s very difficult for xylooligosaccharide’s digestion in intestines. The intestinal survivors of xylooligosaccharides are too much, and can keep a good multiplication for Bifidobacteria. The utilization of the xylooligosaecharide is the highest among the other oligosaccharides. The average yield of the cotton seed hull is very big in China. Most of the cotton seed hull are burnt, although a few are used.It’s very important to do the theoretic researches and the processing technologies about the xylooligosaccharide preparation with cotton seed hull.The xylan from agricultural residues cotton seed hull was enzymatic hydrolyzes into crude xylooligosaccharides with xylanases by Sphingomonas paucimobilis and purified preliminarily xylooligosaccharides through the active carbon.With the HPLC repeat detection,The gossypol content of the Cotton Seed Hull was 0.0163%, in line with provisions of the United Nations Advisory Committee （the gossypol content in Cotton Seed Hull should be less than 0.06%）,Cotton Seed Hull can be used as food processing materials. the advantage of Cooking method and alkali extraction were consolidated,the optimum pretreatment process conditions of xylan were as follows: the quantity of water was 15 mL·g-1,115℃f or 45 minutes,After pretreatment, the optimum extract process conditions of xylan were as follows: the ratio of water and cotton seeds hull was 20, and the concentration of NaOH was 8%, 110℃for 1 h.The yield of crude xylan was 62.8%.Xylanase producing strains were isolated from special environment NANSHANFOREST and deadwood,XINJIANG etc. Isolates of strains were obtained and assayed for the xylanase activity with a method of transparent zones.10 strains presented the highest activity were selected for further investigation in detail.According to the morphological and physiological characteristics and the result of TLC test,NS5 was identified as Sphingomonas paucimobilis; Research aboutβ-xylanase production showed that the other carbons catabolite repression existed during the producing of target enzyme,xylan was the best carbon source as well as the elicitor. The media contained the surfactant （Tween80 0.08%）was added,which could improve the ability of enzyme production markedly. Under the condition of inoculation concentration 10% and initial pH 8.0 of the medium and 31℃of the culture temperature,the optimal culture time was 96 hours and the maximum enzyme activity of 36.2 U·mL^-1 was obtained at 190 rpm.The optimum conditions were at 30℃with the enzyme concentration 15%, the reactive time was 8 hours, the concentration of substrate was 40 g·L-1,the above reaction conditions for enzymatic hydrolysis yield was 53.2%. The optimum conditions of activated carbon decolorization were as follows: the amount of activated carbon 2 g·L^-1, decolorizing temperature at 50℃, decolorizing time 50 min,The HPLC showed that 48.56% of the refined oliosaccharides are xylobiose and xylotriose, and 82% are xylooligosaccharides.In this paper, the results of research to improve the use of cotton husk opened up a new way to address both the agricultural and forestry waste. It has also solved the problem of environmental pollution, there is good economic and social benefits.