Cellulose product yields

The sodium salt of CS [9005-22-5] is prepared by reaction of cellulose with sulfuric acid in alcohol followed by sodium hydroxide neutrali2ation (20). This water-soluble product yields relatively stable, clear, and highly viscous solutions. Introduced as a thickener for aqueous systems and an emulsion stabilizer, it is now of no economic significance. 

Grain that is usable as food or feed is an expensive substrate for this fermentation process. A cheaper substrate might be some source of cellulose such as wood or agricultural waste. This, however, requires hydrolysis of cellulose to yield glucose. Such a process was used in Germany during World War II to produce yeast as a protein substitute. Another process for the hydrolysis of wood, developed by the U.S. Forest Products Laboratory, Madison, Wisconsin, uses mineral acid as a catalyst. This hydrolysis industry is very large in the former Soviet Union but it is not commercial elsewhere. 

The FP cellulose per unit (ml) volume and enzyme yield per unit (g) cellulose or substrate obtained on wheat straw, wood, and CTMP in SSF were higher than those obtained in LSF on wheat straw and wood (Tables I, II, and III). And wheat straw proved to be a better substrate than wood for cellulose production in SSF. This could be attributed to the polysaccharides (cellulose and hemicelluloses) of wheat straw being more readily available for the organism s growth and cellulose synthesis than those of wood. The hemicelluloses and cellulose were presumably not as available in wood, because of its high lignin content and high cellulose crystallinity, as in wheat straw. 

R. flavefaciens cells, during growth in pure culture, released cellulase, endoglucanase, and xylanase into the culture fluid. This microorganism hydrolyzed cellulose to yield only cellobiose as a product 49). It had been reported that a ceUobiose phosphorylase and glucokinase were present in R flavefaciens (8). The Ruminococcus cellulase system was repressed by disaccharides such as cellobiose, sucrose, and lactose 50). 

Lunge et al. [15] examined the effect of the composition of mixed add, and the influence of the nitration temperature within the range from 0 to 80°C on the nitrogen content of nitrocellulose, the content of non-nitrated cellulose, the yield, the solubility of the products in ether-alcohol mixture and the viscosity of the acetone solution. Cotton linters were used. From these experiments it has been established that nitrocellulose containing more than 13.5% N is unstable and decomposed readily, as mentioned before. 

The composition of poplar wood was usedasamodel for the feedstock composition however, as used in this simulation, the poplar is modeled as consisting of only cellulose, xylan, and lignin, with compositions of 49.47, 27.26, and 23.27%, respectively. Laboratory results for carbonic acid pretreatment are relatively scarce, so for the purpose of this comparative study, stoichiometry of pretreatment reactions was assumed to be equal to those used in the comparison model (3) cellulose conversion to glucose 6.5% xylan conversion to xylose 75 and lignins solubilized 5%. Thus, economic comparisons made with this model assess different equipment and operating costs but not product yields. For the successful convergence of the carbonic acid model, the simulation required initial specification of several variables. These variables included initial estimates for stream variables and inputs for the unit operation blocks. 

A solution of the adenosine derivative (2 mmol) in 1,0-1.6 M aq chloroacetaldchyde (20 mL) at pH 4.0 4.5 was stirred at 24-37 C for 12-72 h until no starting material was detectable by TLC (on Easterman chromatogram cellulose sheets using i-PrCOjH/NH OH/HjO, 71 1 24, v/v/v) and until the peak ratios 265/275 run became constant in the UV absorption spectra. The etheno product was decolorized with charcoal and evaporated to dryness in vacuo, Recrystallization of the residue by dissolving in a minimum amount of HjO, followed by addition of EtOH and EtjO to the cloud point or reprecipitation from aq EtOH followed by an EtOH wash yielded pure product (yield 90-95%). 

As shown in the model, pyrolysis of cellulose results in solid, liquid and gaseous products. However, the proportions of the product yields can change depending on the process conditions. The knowledge of thermodynamics and kinetics of the reaction pathways allows us to adjust the conditions to maximize the yield of the desired products. 

Biomass is composed of various components such as cellulose, hemicellulose, lignin, extractives and mineral water. The composition of biomass plays a definitive role in altering the product distribution and their properties [2-3J. As is shown in earlier publications [4-S] different biomass, on pyrolysis, give different product yield with different product properties. In order to choose a biomass for a particular process (carbonisation, liquefaction, gasification or adsorbent char) knowledge on the product distribution and properties for various biomass are essential. 

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